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Project Journals => User Journals => Chris Olson => Topic started by: ChrisOlson on January 12, 2012, 01:09:11 pm

Title: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 12, 2012, 01:09:11 pm
I'm going to try to put together an orderly and informational post on my latest wind turbine build for this new forum.  Judging by the amount of private correspondence I've gotten on this project, there is HUGE interest in the concept of both using ferrite magnets in a wind turbine generator, plus using MPPT on it to optimize output of the machine.

The post, when I get it prepared, will have a lot of photos for people to look at.  The old saying is, "a picture is worth a thousand words".  One thing I could point out is that when people do post photos to the new forum, I'm pretty sure (admin correct me if I'm wrong), that it's more efficient for the host server to NOT upload the pictures to the host.  There's outfits on the internet like Picasa Web Albums (which is what I use), or the outfit that TomW uses for online photos (can't remember the name of it right now - PhotoBucket maybe?).

You can link to the photos and make them appear in your post instead of uploading them.  This reduces the CPU time on the server required to do SQL queries to pull the photos out of a database contained on the server.  It instead turns the photo into merely an external HTML request in the page code to make it display in the post.  So the server only has to do one SQL query to pull your post out of the database.  The rest of the work in getting the photo to display is done in page code when your browser renders the web page.  From what I remember about running servers back in the day, this will make the new board (especially if it gets lots of photos) run faster in the long run without getting bogged down when search engine crawlers start indexing and caching pages and images on the site.

So I'm going to try this here to make sure I understand how it works (it's the button on the left right below the "B").  You simply go to where your photo is in another tab in your browser, right click on it and save the image web location, then paste the URL in between the image tags.  This is a photo of the completed turbine on which I will try to explain the complete build in a subsequent post (might take me awhile to put it all together).

(https://lh4.googleusercontent.com/-K7K0sbj3r7Q/TwkCeiVQQUI/AAAAAAAAF0M/mSbS7RAqkwI/s640/100_1288.JPG)

--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Wolvenar on January 12, 2012, 01:43:28 pm
As far as CPU and SQL time go, the hardware that this sits on could handle a lot more than we need to worry about with a site like this.
However that said, the best ( in my opinion ) option is to upload images to the gallery here at anotherpower
http://www.anotherpower.com/gallery/ (http://www.anotherpower.com/gallery/)
This gallery keeps an original sized  and resizes an image so the largest dimension is 640. This intermediate size works good to link to. Since these images are not stored in SQL it does not then cause issue there.
For todays computers running a standard resolution ot 1024/786 or more this seems to display well in a post

This also has the benefit that images are not lost in posts if an off-site hoster goes away, changes its guild lines or you have to make room for something else by deleting images when you find you have hit your storage limits.

This gallery here has essentially no size limitations, nor is there any limit on how much you can add. However it seems to have a little bit of a fit if you upload an enormous amount of large images in one upload.

Some images not relevant to RE are of course acceptable, but use common sense about stuff like that.


Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 12, 2012, 03:28:22 pm
This gallery here has essentially no size limitations, nor is there any limit on how much you can add. However it seems to have a little bit of a fit if you upload an enormous amount of large images in one upload.

Thanks wolv - working on putting an album together of the 3.2 meter  turbine photos.

Quote
Some images not relevant to RE are of course acceptable, but use common sense about stuff like that.

Ok, photos of bikini-clad wife go in Global Warming album    ;D
--
Chris
Title: part 1 - design
Post by: ChrisOlson on January 12, 2012, 04:30:25 pm
All the photos here (and more that I won't post) can be viewed in the album for this turbine here:
http://www.anotherpower.com/gallery/ferrite-magnet-MPPT-turbine

The first photos start out with the gearbox design and layout.  I had decided early that this turbine was going to use an angled hinge tail, with the tail working against gravity, for the furling system.  So I offset the PTO shaft in the gearbox to move the generator slightly away from the yaw axis, and thereby allow more room for the tail hinge.  In the end, this worked out quite well.

The gearbox has a .400:1 gear ratio, meaning the turbine's generator runs at 2.5x input shaft speed.

My original idea with a MPPT-controlled wind turbine was to use a Midnite Solar Classic 150 controller on a 3.8 meter turbine, with a dual stator ferrite generator, modified with high voltage stators.  I tested this setup (with a stock stator set) with a hydraulic motor driving the turbine's gearbox input shaft, with the Classic 150 hooked up, and a "real world" wire run to my battery bank, to get an idea of how the controller works and how a stock 24V generator pans out with MPPT on it.

What I learned was that it is quite easy to get 2.5 kW out of this setup with way less shaft power input required than what a 3.8 meter rotor can deliver.  I discovered I don't really need the raw amp capacity of the dual stator generator, but I could use more voltage input to the controller to make the gen, rectifier and wire run more efficient.

I think it was about that time that I decided to downsize the turbine to 3.2 meters and use a different style of blades on than GOE222's (which is what I had used on previous turbines).

So I went to my CAD (Cardboard Assisted Drawing) design system to look at possibilities for a generator for it:
(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1162.sized.jpg)

I initially looked at 10 pole stacked two-phase layouts.  But then the light bulb came on over my head one cold night and I decided to figure out a three-phase single stator layout that would give me adequate amps and more volts for the amount of rotating mass and copper used in the generator.  This is a CAD layout of coils that were actually wound for a 10 coil single phase stator.  But the pin dimensions and volt turns ended up working out fine for a 16 pole 12 coil three phase design, as well - with the added advantage of getting more volts out of the thing:
(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1167.sized.jpg)

Based on my testing run, I developed a spreadsheet to figure out how to match rotor rpm and available shaft power to rpm/volt from the generator, and to the load.  My initial idea here was to have 119 open volts @ 400 rpm.  But later on in the build, after studying the NREL testing data on the S809 airfoil that I'm using, I decided I needed to run the rotor faster (480 rpm @ 12.5 m/s) to get enough shaft input power to make a 2.5 kW turbine out of this thing.  I made a YouTube video explaining that decision that you can watch (hope this YouTube thing works - couldn't get it to come up in the Preview)


--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Wolvenar on January 12, 2012, 05:29:18 pm
Looks like some nice work there Chris
Title: part 2- transmission and main frame
Post by: ChrisOlson on January 12, 2012, 09:08:04 pm
On my previous geared turbines I placed the gearbox inline with the yaw shaft.  With the heavy 3.8 meter rotor and lightweight neo generator they were balanced pretty nice on the yaw.  However, once I retrofitted them with dual stator ferrite generators, the extra weight of the generator caused them to be slightly tail heavy.  Those machines had a long input shaft housing that placed the rotor well forward of the yaw.

On this one, the rotor is lighter than the 3.8 meter.  And the generator is heavier than a neo.  So I attempted to move the weight forward as much as possible.  I also wanted less offset (130 mm) with the smaller rotor.  So I placed the gearbox ahead of the yaw and inclined the input shaft at 6° from horizontal

(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1131.sized.jpg)

This one will not have an input shaft housing.  This is the input assembly for it, and with the input shaft test installed in the gearbox

(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1146.sized.jpg)

(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1143.sized.jpg)

It looks like the rotor is a long ways out front.  But this style rotor is for a downwinder.  So the blades have a pretty radical sweep backwards at the root of the airfoil.  There's not as much room there as it looks like there is.  The blade roots clear the front of the gearcase by about 30 mm.

(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1290.sized.jpg)

The tail hinge is welded on at 18° angle and 40° to the side of being straight back from a parallel line drawn thru the input shaft and yaw centerline.  I also put a spring loaded damper on the tail return

(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1256.sized.jpg)

After building and welding a stator mount to it, and building the tail boom, it's ready for assembly

(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1262.sized.jpg)

--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dave B. on January 12, 2012, 11:38:03 pm
Hello Chris,

  I got through the registration and the move successfully I guess. Great to see your latest videos on the turbine and I had to laugh at you being over ruled on the blade color. I like the look of those blades and will be anxious to hear of their performance with the new turbine. I know plenty are watching as well, let it fly !  Dave B
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 13, 2012, 09:35:53 am
I'm the most fortunate guy on earth because my wife takes an interest in all my wind power projects.  And she comes out and helps with the turbines especially during installation, pulling the drop cable thru the tower, helping me lift and install an assembled rotor - she even wired a stator up on one once.  So if she wants white blades on it, what the heck - white blades it will have.

Wait until she sees it run tomorrow when I finish getting the clipper built and installed.  This one is a right hand turner - the rest are left hand.  I can almost see it now - she'll be standing there with her hands on her hips looking up at it and go, "You put the blades on backwards."

And by gully she'll right once again - these blades are for a Talon downwinder   ;D
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: rossw on January 13, 2012, 02:18:22 pm
I can almost see it now - she'll be standing there with her hands on her hips looking up at it and go, "You put the blades on backwards."

And by gully she'll right once again - these blades are for a Talon downwinder   ;D

Silly question, don't laugh!

Is there any rationale at all for the conventional anticlockwise rotation?
I mean, ok, if one had nuts and threads that would work loose - fine. But many of the commercial ones I've seen have a keyed shaft, and with a locknut or castellated nut, they're not going to come loose anyway.

Or is it just convention? The first ones were made that way, and everyone makes them that way "because thats the way everyone else makes them"?
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 13, 2012, 03:04:51 pm
Is there any rationale at all for the conventional anticlockwise rotation?

Yeah, it depends on which side of the equator you live on.

No - that was just a joke    8)

That's kind of an interesting question.  All major horizontal axis turbines today rotate the same way (clockwise) because it's supposed to present a coherent and pleasing view.  Early turbines rotated counter-clockwise like the old windmills, but the change to clockwise rotation happened after about 1978.  One of the blade suppliers back then in Denmark made the decision to change direction in order to be distinguished from the Tvind (in Denmark) and their small wind turbines.  Some of the blade customers were companies that later evolved into Vestas, Siemens, Enercon and Nordex.  Since public demand required that all turbines rotate the same way, the success of the Big Four made clockwise the new standard.

The only other rationale is that it's "ideal" to have the blades turning the opposite direction of furling when looking at the machine from upwind.  In other words, if you have a left hand furler, ideally you should have right hand (clockwise) rotating blades.  And vice versa.

The reasoning behind that is to help prevent a tower strike during rapid furling.  For instance, with a left hand furler, left hand turner, the bottom of the blade circle will flex towards the  tower during a rapid yaw event to the furling side.  Put right hand turners on that same machine and the bottom of the blade circle will tend to flex away from tower during rapid yaw to the furling side.

But still, which way the blades turn and which way it furls cannot "fix" an improperly designed machine that does not have enough forward "lead" of the rotor to the yaw axis.  Nor "fix" a tip-to-tower clearance problem caused by not having enough inclination of the input shaft from horizontal.  If you have adequate blade tip clearance to the tower, you won't have a problem with either one.

So basically the "standard" came to be because the human mind tends to prefer a right hand (clockwise) rotating machine, as it's supposed to be associated with symmetry somehow, or "the way things should be".  But for somebody as screwed up as I am, even that doesn't make any difference   :D
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: frackers on January 13, 2012, 04:27:33 pm
Is there any rationale at all for the conventional anticlockwise rotation?

For me it depends on which way it furls. I changed the direction of mine as I'm sure that the generator was lifted off the yaw bearing by the gyroscopic precession forces as the mill violently furled during a large gust. According to my calculations now, during the same conditions the force will be down rather than up.

And guess what - 6 weeks ago I ended up with a bent tower which may well have been the extra downward load due to exactly those forces >:(
Title: part 3 - the generator
Post by: ChrisOlson on January 14, 2012, 06:41:09 pm
After making the decision to use a single stator three-phase generator on this turbine, this was obviously going to require bigger diameter generator rotors than the dual stator two phase ferrite units I had built in the past.

My CAD (Cardboard Assisted Drawing) indicated that I could get the magnets to fit on 355 mm diameter rotors with just a tiny bit of room to spare (~2-3 mm) between the corners of the big 51 x 51 x 25 mm thick C5 ferrite blocks.  I machined the rotors true and to 5 mm thickness, plus milled some lightening holes in them to reduce rotating weight:

(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1183.sized.jpg)

This is a finished rotor - they ended up at 10.4 kg (23 lbs) each.  I also welded "claws" on these rotors, like I have done with my other ferrite generators, to hold those heavy magnets against centrifugal forces.  There's a lot of confusion over putting the "claws" on the outside of the mags, as this is supposed to "steal" flux.  But I did a lot of experiments when I built my first ferrite generator, and determined it doesn't make one bit of difference.

One thing about this layout is that I'm "wasting" the corners of the magnets by placing them this close together.  I'm getting the same flux in the air gap as I would if I used wedge-shaped magnets.  But being these magnets are readily available, and cheap ($1.84 each), the extra cost of having custom wedge magnets machined is not worth it.

(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1189.sized.jpg)

Then I turned a pile of coils into a stator - it's wired wye, 45 turns of 13 AWG per coil, it ended up at .55 ohm internal resistance.

(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1185.sized.jpg)

(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1217.sized.jpg)

(http://www.anotherpower.com/albums/ferrite-magnet-MPPT-turbine/100_1220.sized.jpg)

The initial test after assembly of the generator showed it produced 119.1 open volts @ 1,000 rpm with the air gap at 18.5 mm.  I later tuned this back just a tad by opening up the air gap to 19.5 mm so it would produce 115.4 open volts @ 1,200 rpm.  This will let the rotor spin 480 rpm @ 12.5 m/s instead of 400 rpm, and still maintain the max 100 volts (loaded) that I want to operate the generator at at full power.  I don't want to tune for over 100 volts to allow some "breathing room" for the Classic controller if the turbine were to become unloaded due to over-amp of the controller.

The voltage clipper will come on (controlled by the Classic's Aux 2 output) at 145 volts.  But the clipper is a three-phase wye resistor @ 6 ohms, and can only handle 3 kW of power for a short time.  If the turbine were to unload due to over-amp, hopefully the clipper will keep its operating voltage under the controller's 150 volt limit.  This remains to be seen, as it hasn't been tested.  You can rest assured I will monitor it very closely with my hand on the emergency shutdown the first time we get 15-20 m/s wind, until I'm convinced it works properly.

Now all that's left is to put it together and get it on the tower.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: halfcrazy on January 15, 2012, 06:08:33 am
Chris
Very nice work. I love following your posts and wish I had the time to try something new.

Ryan
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: bj on January 15, 2012, 07:18:02 am
   Chris--quick question--what kind of tape did you use on the coils?  You may have said, but couldn't find
it.
   Thanks in advance.
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 15, 2012, 09:53:58 am
bj, I bound the coils in this one with regular old 3M painter's tape.
--
Chris
Title: part 4 - it's running!
Post by: ChrisOlson on January 15, 2012, 12:27:28 pm
Pictures are fine.  But movies are cooler.


The gen runs so fast on this turbine that it looks like it's going backwards at slow speed in the video.  It started up at about 2.5 m/s and it takes awhile with the blades running on pure drag to get it spooled up in light wind.  When the rotor hits about 120 rpm, the airfoils start making decent lift and it comes to life.  Once it's running the heavy generator mass seems to help keep its output very smooth, without the ammeter wandering all over the scale.

The new turbine is delivering right around 1 kW @ 9 m/s (20 mph).  Seen one peak at 2,272 watts so far.  My anemometer recorded a peak gust of 11.6 m/s (26 mph) that corresponds with the 2.27 kW power peak.  It's running right around 70-75 volts @ 9 m/s and 1 kW.

The wind always stops blowing when I put up a new turbine.  But it started picking up about 10:00 this morning.  1.46 kWh so far today from it, and counting......

This turbine flat out RUNS - and the trans isn't even broke in yet.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 15, 2012, 02:49:12 pm
I like the look of those blades and will be anxious to hear of their performance with the new turbine.

Dave, these 3.2 meter blades are basically useless below 120 rpm.  Once they get to 120 they start making decent lift and they accelerate VERY fast.  They got a higher Cp than the GOE222's and it really shows in the higher wind speeds.  This 3.2 meter is literally walking all over the 3.8 meter machines here today in decent wind.  It's .8 kWh ahead of the closest 3.8 meter turbine, and putting on more distance with every hour.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dave B. on January 15, 2012, 04:28:22 pm
Great Chris, videos are very cool. I have always been a fan of large pitch at the root for blades, you don't see it much for home brew because of the extra work and the assumption that there is little work done on the inner 1/3 of the blade. A tapered twisted blade uses all of the blade in all wind speeds efficiently, that's why the blades look as they do. A large drop at the root is not just for start up, it pulls hard for it's own slower tip speed at any rpm for that section of the blade.

 Keep us posted, this has been a great project for others to learn from as well.  Dave B.
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: artv on January 15, 2012, 06:23:26 pm
Chris;
I find your work to be, the best of the best ,excellent
I have been logged on now for about 90 minutes trying to load that link you gave about water pumping ,in the other thread ...........not gonna happen
But I'll take your word for it ....
Your lucky your not my nieghbour , I'd drive you crazy with questions :)
Thanks for your postes.....invaluable........Art V
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 15, 2012, 09:14:55 pm
A tapered twisted blade uses all of the blade in all wind speeds efficiently, that's why the blades look as they do.

Dave, these blades have 18° pitch at the root and 1.5° at the tip.  They're an S809 airfoil, which is used on most of the commercial turbines today.  The S809 is symmetrical except for a "cusp" on the trailing edge of the wind facing side of the blade.  They like to run from 6.5-7.0 TSR, and will run quite well down to 6.0 TSR.  Below 6 their Cp drops off pretty fast and they stall very easily.

I tweaked the power curve in the Classic's graphic editor today to let the turbine run at higher voltage and 7.0 TSR instead of 6.5.  That got me another 120 watts @ 9 m/s.

This turbine is quite noisy at higher wind speeds.  It sounds like somebody whipping three 1/2" cables thru the air at high speed.  At 5-9 m/s it's not too bad.  But at 10-12 m/s it sings pretty good - the rotor is running well over 500 rpm @ 12 m/s and I got just shy of 2.9 kW from it so far, which pushed the Classic to 95 amps output.  Believe me, a 3.2 meter turbine @ 2.9 kW output is screaming like a banshee.  I'm going to tune that back a bit by "clamping" the input voltage down a bit in the Classic's graphic editor to cut it back on the top end.  But for now it's a new "toy" and I want to see what it'll do   :)

We still got good wind tonight but it's tamed down a bit from what it was earlier.  It's averaging 9-10 m/s right now and supposed to die down further tonight.  But I'm happy with it - it had a good first day's run on the tower - 10.1 kWh since 10:00 AM.

What's really cool is that I ran a permanent ethernet cable from the Classic to my home network wireless router.  I downloaded a thing off Midnite Solar's website that lets me access the Classic over my network with my laptop.  I can sit right in my easy chair and watch my turbine's performance on gauges and stuff on my laptop.  Never had anything like that before and it's cooler than hell.

Just kind of a sidenote on setting up the Classic 150 for your home computer network - when I first set it up I used DHCP but I couldn't find it on the network.  Something either mucked up in my Workgroup or whatever, and it wouldn't show up.  I gave it a static IP address and then it showed up and the Local Status Panel in my computer can find it.  Don't know what the deal is with that.  But it works.

Edit on the blade topic -
Dave, I got another set of these blades here and I measured them up this morning.  I don't know if it would be possible to carve these or not.  You'd have to use blanks that are 4" thick x 10" wide.  These blades appear to be designed so the entire length of the blade runs at the same angle of attack.

The airfoils are almost perfectly symmetrical except for about the last 1/2" of the trailing edge where there's a slight "cusp" on the wind-facing side.  This is the airfoil these blades use.  It doesn't even look like it would work, or generate any lift, but it does:

(http://wind.nrel.gov/airfoils/Shapes/S809.gif)
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dave B. on January 16, 2012, 01:58:12 pm
Chris,

Thanks for the info. on the blades, it's all a matching thing for a system as you certainly know. I like thise blades. Your Classic should help you tweak the system and it's great to hear you are monitoring now from your easy chair. I do this with mine as well and I'm sure you could go remote with it also, it is very cool stuff indeed. Keep us posted on the performance of this machine, you have many followers now over here and few if any telling you it shouldn't be done this way or that. (Cool videos)   Dave B
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 16, 2012, 02:40:01 pm
I found a little "trick" in adjusting the power curve to make the turbine run quieter.  I cut the thing in way early (about TSR 6), then let the voltage climb by 4 volts for 2 amps output up to where the rotor is running at TSR 7, or a little better.  Then flatten the curve out a little bit and gradually "lug" the rotor back down to TSR 6 by the time the wind speed gets up to 12 m/s.

This makes the rotor run slower at lower wind speeds, which helps the noise a lot and doesn't really hurt output very much.  Then it lets it speed up to maximum efficiency in the midrange wind speeds where the noise from the wind helps dampen some of the noise from the rotor.  On the top end it keeps the rotor speed down to 450 rpm and limits output to about 2.2 kW.  That's working really good.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: bvan1941 on January 16, 2012, 03:07:40 pm
Chris,
really, really nice design, engineering concepts and actual working units with predicted results !!
Whats even better, your increasing the limits of output and efficiency in the normal ranges of wind that we realistically see. Kind of makes us laugh at the "pro's" claims for the junk they advertise as "break through" in micro wind technology!
Keep up the great work and documentation. You have a lot of fans out here.
Bill
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 16, 2012, 03:21:53 pm
Not totally predicted because I ended up having to run the blades a bit faster than I originally calculated I would.  I'm still trying to "tweak" out a power curve that doesn't lose anything to a direct hooked machine in the low winds (due to controller loss), and run at peak efficiency in the midrange wind speeds.

In higher winds you can open this thing right up and let it scream.  But that's really not practical for the long run because it will shorten the life of the blades.  By "capping" the voltage at about 90 it makes all the power you need in high winds anyway, without stressing stuff out.  It's kind of fun to push everything right to the smoke limit to see what it'll do.  But I'm concentrating on tuning the power curve for midrange right now.

There's supposed to be a "dithering" feature for the Classic coming out in a firmware update.  I haven't checked to see if that's available yet.  But this feature lets the Classic "dither" the power curve to "learn" the peak power point.  That would be kind of fun to see what it does.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Watt on January 17, 2012, 08:10:12 pm
Not totally predicted because I ended up having to run the blades a bit faster than I originally calculated I would.  I'm still trying to "tweak" out a power curve that doesn't lose anything to a direct hooked machine in the low winds (due to controller loss), and run at peak efficiency in the midrange wind speeds.

In higher winds you can open this thing right up and let it scream.  But that's really not practical for the long run because it will shorten the life of the blades.  By "capping" the voltage at about 90 it makes all the power you need in high winds anyway, without stressing stuff out.  It's kind of fun to push everything right to the smoke limit to see what it'll do.  But I'm concentrating on tuning the power curve for midrange right now.

There's supposed to be a "dithering" feature for the Classic coming out in a firmware update.  I haven't checked to see if that's available yet.  But this feature lets the Classic "dither" the power curve to "learn" the peak power point.  That would be kind of fun to see what it does.
--
Chris

Very nice Chris. 

Be careful pushing that classic to the " smoke limit ", that will for sure cause you to park your new toy until a replacement arrives.   :o

Keep us posted for sure. 
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: halfcrazy on January 18, 2012, 06:03:07 am
Not totally predicted because I ended up having to run the blades a bit faster than I originally calculated I would.  I'm still trying to "tweak" out a power curve that doesn't lose anything to a direct hooked machine in the low winds (due to controller loss), and run at peak efficiency in the midrange wind speeds.

In higher winds you can open this thing right up and let it scream.  But that's really not practical for the long run because it will shorten the life of the blades.  By "capping" the voltage at about 90 it makes all the power you need in high winds anyway, without stressing stuff out.  It's kind of fun to push everything right to the smoke limit to see what it'll do.  But I'm concentrating on tuning the power curve for midrange right now.

There's supposed to be a "dithering" feature for the Classic coming out in a firmware update.  I haven't checked to see if that's available yet.  But this feature lets the Classic "dither" the power curve to "learn" the peak power point.  That would be kind of fun to see what it does.
--
Chris

Very nice Chris. 

Be careful pushing that classic to the " smoke limit ", that will for sure cause you to park your new toy until a replacement arrives.   :o

Keep us posted for sure.

Oh Chris knows the Warranty guy at MidNite it wouldn't take long for me I mean them to get him a new Classic ::)

Ryan
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 18, 2012, 01:26:43 pm
When you first put it in with a new turbine you have to see what it'll do.  You just have to do it.  It's like if you manage to cob onto a '68 426 Hemi Roadrunner.  You're just going to drive it around like an old Grandma?  Yeah, right.  You and I both know you're going to smolder at least one set of tires off it just because you have see how many city blocks you can paint continuous stripes on the road.

I got it "tuned back" a little now by not letting the voltage run as high.  But I just had to prove to myself that you can indeed get dang near 3 kW from a little 10 foot turbine if you let it run Balls Out (to borrow an old steam engine term).

One thing I learned by doing that is that the turbine refuses to furl at all if you start pushing it to 550+ rpm.  Keep the rotor speed down to 400-450 and it furls fine.  Don't really understand the dynamics behind that.  But it'll wake you right up when the ammeter needle heads to the top of the scale and you just stand there watching it going, "It should be furling Any Time Now®".  But it don't.  So you go, "WTF?????", rush out the door to take a look and the confounded thing is facing dead on into the wind running FFO (Flat Freaking Out).

At that point there was several courses of action that went thru my brain in a couple milliseconds, as to how I was going to handle this situation before I got something smoking.  But, fortunately, the wind gust died down and it cut back by itself.

Just like the Roadrunner deal, it all boils to to, "you just have to do it".  But I did learn some things from it:
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Jarrod9155 on January 18, 2012, 01:51:26 pm
Most be mppt my turbine does the same thing if you let it build rpm on the top end no furl !!  My cure was turning on my heating elements at the last two steps of the curve .If I catch it just early enough before the blades get optimal tsr above 20 mph I start to stall them enough to engage furling  My prediction is if you do go with the goe222 blades you will find that controlling it above 20 mph plus winds will be fun !!! More the load it seems the faster they go!!
      In my case I should never reach 600 volts that's we're the magic smoke comes out of the inverter even in a runaway . But in your setup I bet that thing could easily reach your max volts .
       Looking good !!
    Maybe a omron relay to switch away your turbine in case of a runaway . I use one to switch on dump loads and switch of the turbine if the grid fails .
 
  Jarrod
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 18, 2012, 02:59:18 pm
    Maybe a omron relay to switch away your turbine in case of a runaway . I use one to switch on dump loads and switch of the turbine if the grid fails .

Jarrod - I built a three phase wye resistor and am driving it with PWM using the Classic's Aux 2 output with a SSR.  I was going to do it with mechanical relays at first.  But then decided against that and built a system like it shows in the manual with "Ryan's Clipper" because that's proven and it works.

The biggest problem I got right now is that I turned down the voltage a bit and the clipper has too much resistance so it don't draw enough power.  I need to shorten the heating coil springs on my clipper resistors so it draws more power at lower voltage.  Then it will be fine.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: rossw on January 18, 2012, 11:59:54 pm
The biggest problem I got right now is that I turned down the voltage a bit and the clipper has too much resistance so it don't draw enough power.  I need to shorten the heating coil springs on my clipper resistors so it draws more power at lower voltage.  Then it will be fine.

Is it practical to just "jumper" part of the coil? Might be quicker, easier and more versatile if you can bring in as much (or as little) resistance as you need? At least while you're fine-tuning it.

It's a b!tch when you take out a whisker too much and have to start again!
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 19, 2012, 10:01:24 am
Is it practical to just "jumper" part of the coil? Might be quicker, easier and more versatile if you can bring in as much (or as little) resistance as you need? At least while you're fine-tuning it.

I certainly could do that.  The resistor I built is made from some 6,500 watt 240 volt heating elements that I found, that came out of an electric furnace.  Each element had a spring about 10 feet long and it was arranged in a weave pattern, strung thru some ceramic insulators.  I measured along the springs with my ohm meter until I found a point where the resistance was 3 ohm, then cut the springs off to that length.

When I built the resistor I wired it wye so my resistance is 6 ohm.  At 100 volts that only draws 17 amps for a 1.7 kW load.  I actually need it closer to 3 kW load, so I have to cut the springs just about in half again.

I got one leg of the turbine generator going directly to one terminal on the resistor.  The other two terminals are powered up by a two pole SSR driven with PWM.  I think it's actually OK to have too much load because the PWM will regulate the voltage by varying the pulse width to the SSR.  So I'm pretty sure if I cut the springs in half I will have 3 kW @ 100 volts (or maybe even slightly more).  This should handle the full output of the turbine OK with it disconnected from the DC load.

In theory, it should never have to use the full capacity of the clipper unless the breaker between the Classic and battery should trip.  During "normal" operation when there's a DC load the clipper only comes into play when the Current Limit in the Classic is reached, which I have set at 84 amps now.  The clipper then only has to handle the excess power over the 84 amp DC load to hold the voltage at 100 volts.

So I think I have two options - either rewire the springs delta, or leave them wye and cut them about in half.  Rewiring them delta would lower the resistance to about 2 ohm, while cutting them in half would lower it to about 3 ohm.  I think the 3 ohm load is closer to what I need.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Jimf on January 19, 2012, 02:23:26 pm
Quote
So I think I have two options - either rewire the springs delta, or leave them wye and cut them about in half.  Rewiring them delta would lower the resistance to about 2 ohm, while cutting them in half would lower it to about 3 ohm.  I think the 3 ohm load is closer to what I need.

Another option would be to make another set of resistors like you have, wire the two sets in parallel, and you will have double the load without stressing the resistor any more than you are now.

Keep up the posts, this is the kind of project I like to see!

Jim
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Wolvenar on January 20, 2012, 04:10:35 am
I agree, I would like to see a litlte of how your control systems, and inverters are setup ( with some images)    ;D
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dale S on January 20, 2012, 05:54:33 am
Be careful what you ask for. ;) I'ts cool as hell but pretty elaborate, I can almost guarantee you've never seen anything quite like it.
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 20, 2012, 09:37:37 am
I'll have to do a walkthru of that sometime.  System and load control is done with two Morningstar RD-1's and a Xantrex ALM.  One RD-1 has temp input on Channel One and turns on generator pre-heat (block and oil pan heaters) when the ambient temp drops below zero F, plus handles water heating loads.  We have two water heaters.  Only the bottom element on the primary heater is power-on all the time with the stat set at 125 degrees, so we always got at least 55 gallons of 125 degree water.  I replaced the standard 4,500 watt element with a 2,500 so it doesn't take over half my inverter capacity to run it.

The top element, and both elements in the secondary (pre) heater are used as "dump" for wind systems.  They're still powered by 240 VAC, but the RD-1 and Xantrex ALM turn them on in stages to control bank voltage when the wind is blowing good.  I do not have any DC "dump loads".

The second RD-1 shuts down the wind systems, one at at time, when both water heaters get up to 170 degrees.  And it puts the turbines back to work one at a time as power is needed again.  On a good day with both water heaters at 170 none of the turbines will be running and the solar will be floating the bank and carrying the loads.  On a bad day when the sun only shines in Argentina and the wind only blows at South Pole Station, the generator will be running.

Like Dale said, you've probably never seen anything like it.  I spent a LOT of time (and money) getting it to work the way I wanted it to, so I can just walk away and do other things and it takes care of itself.  The only real PITA is that those RD-1's are in the utility room and when I want to change some operating parameters of the system I have to lug my laptop out there to program them.  They only have RS232 serial connection.  One of these days I'm going to pick up a StarTeck RS232 - > IP ethernet server and connect them to  my network router.  But I'm saving that for when I really start getting lazy   :)
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: rossw on January 20, 2012, 02:43:27 pm
The only real PITA is that those RD-1's are in the utility room and when I want to change some operating parameters of the system I have to lug my laptop out there to program them.  They only have RS232 serial connection.  One of these days I'm going to pick up a StarTeck RS232 - > IP ethernet server and connect them to  my network router.  But I'm saving that for when I really start getting lazy   :)

Watch ebay for a used Lantronix ETS8P. I have a couple of them here, and they're great for this purpose.
Each device has 8 RS232 ports, individually addressable.
I have one, for example, that connects my house automation system, weather station, security system, touchscreen, PABX, lightning sensor and a couple of 4-channel RS232 temperature sensors. The other one is out in a different equipment room for other stuff (inverter, charge controller etc). They don't take much to run, are reliable and stable. Perfect for constant logging and occasional control/reprogramming. Leave everything connected, just run your software as required.
The only downside with the ETS8P is the RJ45 modular connectors they use, TX and RX each come out on 2 conductors, so you need to muck about with cables for D25 or D9 - they're not just straight through or one-wire-per-pin. I think I picked up my spare one for $30 including delivery. (Oh, and they are made with the provision for a fan but I've never seen one with the fan installed. I usually put one in - if they get over about 50 deg C, I've had them lock up and need a power-cycle. But then, you probably never see those sorts of temperatures!)

Just went looking for any photos I might have of them - here's one:
(http://house.albury.net.au/20dec2008/100_3089.JPG)

(http://house.albury.net.au/20dec2008/100_3087.JPG)

Here's one modified to add in the fan. (They have two boards, stacked in the case. This is the power-supply board, obviously)
(http://house.albury.net.au/20dec2008/100_3082.JPG)

It's a bit of a mess, but here's my homes central network/phone patch panel. The ETS8P is on the top, with its lid open - this was before the fan modification.
(http://house.albury.net.au/19dec2008/100_3078.JPG)
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dale S on January 20, 2012, 03:11:52 pm
Jumpin Jehosephat!
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 20, 2012, 04:05:57 pm
Watch ebay for a used Lantronix ETS8P. I have a couple of them here, and they're great for this purpose.
Each device has 8 RS232 ports, individually addressable.

That's a good idea.  I never thought about looking for one on eBay.  But I would like to have one, and I could use at least a four port because my solar MPPT controllers got the same setup and use the same software.

Sometimes I might tweak something by just a couple tenths of a volt, or change a minimum-time-on timer on a water heater element or something.  It sure would be nice to not have to take my laptop out to the utility room and find a place for it to set within reach of the serial cable so I can program something really simple in a controller.

I got kind of spoiled by the Classic controller because it has built-in ethernet and I hooked it into my home network.  I can log on that thing any time I want over my wireless and see what the turbine is doing.  It's got a bunch of chrome bezel gauges that pop up on my laptop screen that show input voltage, watts, and bunch of other stuff.  It even shows what the FET temp is in the controller.  It's pretty cool   :)
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 21, 2012, 03:23:50 pm
Kind of a summary to this project;

My first clipper got burnt to a crisp a few days back because I didn't understand that the Classic functions as a charge controller on wind power.  When it reaches absorb voltage (or float, depending on the SOC of the bank) it starts unloading the turbine by letting the voltage (and rpm) climb to maintain the absorb (or float) voltage.  My first clipper was not powerful enough to handle the excess power from the turbine when the Classic did this.  It burnt my heating coil springs into black carbon.

It does the same thing when it hits the Current Limit you have set in the Charging Menu.  I have mine set at 94 amps, but the Classic will de-rate itself, depending on temperature.  When it hits the Current Limit it will start unloading the turbine and let the voltage (and rpm) climb.

So I had to re-think my whole concept on this because on any good day with both wind and sun the turbine will be running up against the clipper continuous when the bank gets charged up.  I don't want to "waste" that power.

So, I re-configured my water heating system.  Instead of using the RD-1 to turn on three elements, I am now driving them with an Omron two-pole SSR and the Classic's Aux 2 output providing the PWM control signal to the SSR.  I ran one leg from the turbine directly to the delta-wired elements, and turn on the other two legs with the SSR.

I ran to Menards this morning and bought three 2200 watt 120 volt water heater elements and screwed 'em into the heaters.  I put a 2200 in the primary heater for a bottom element, and in both the top and bottom in the pre-heater.  Then switched the 2,500 from the bottom of the primary heater to the top.  That 2,500 watt is the one that's always on (with the thermostat), powered off the inverters.  The three elements, wired delta, came in at 4.2 ohm so it'll pull over 3.4 kW @ 120 VAC.

If the Juice Cop or Building Cop, or whatever Cop it is that inspects wiring, ever comes to our place to inspect stuff, and sees those two water heaters with jumpers running between them to wire three elements delta three-phase, he'll probably have a conniption and tip over in a coma.  But the frickin' thing works, and it works good.

It got tested before we lost our sun for the day, but now we got a stiff breeze from the SE.  I "cheated" by setting the absorb voltage on the solar MPPT controllers a couple tenths of a volt above the Classic.  This makes the Classic start diverting the turbine three-phase AC to the water heater (with PWM) just early enough so the solar controllers don't "throttle back" the panels at the same time when bulk is done.  So the solar is still working at full power, and as the bank comes up and requires less amps to hold the absorb voltage, the turbine with the Classic on it proportionately gets switched over to just water heating.  At that point its full power is no longer required for battery charging, letting the rest of the system do its job and get the bank thru absorb into float.

That array of three 2200 watt 120 volt elements seems to track the shaft power of the turbine pretty nice with changing wind speed.

So I'm happy with the thing now.  With a matched aux heating load available for it I'll never have to worry about a runaway again (unless an element burns out).

I bought another Classic controller after I figured out that I like the first one really well.  It came in the UPS truck a couple days ago.  I'm going to build another turbine just like this first one because it's beating the bigger 3.8 meter machines hands down in kWh every single day.  I thought about putting the new Classic on one of my 3.8 meter machines, but then decided against it.  The type of blades on those turbines (GOE222) are simply not suited to MPPT, and they will not perform well with it.

This one has been fun.  And a HUGE learning curve.  But now that I got it "tuned" I like it.  I REALLY like it.  Time to get to work on another one.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Volvo farmer on January 22, 2012, 08:08:30 am
I'm curious why you believe different blade profiles are more or less suited to MPPT.  I'm thinking of doing some modifications to my 10' Otherpower axial flux turbine, since I am also running a Classic.  Maybe dumb it down for me a little. I sorta understand how pitch affects torque, and that some blades really start to pull once they are up to speed due to the aerodynamics kicking in.

It would probably take me years to fully understand this so maybe you can just give a recommendation. If you had a turbine like mine, with the big round magnets, and stator wired for 24V, what modifications do you think I could make to make it work better with MPPT? Right now I'm flying it exactly as it was when it was direct tied to batteries, and it worked pretty good that way.  It runs a little faster through the Classic now, but still furls well.

I'd prefer not to make a new stator, though I wouldn't mind fooling with the air gap (I could go a lot smaller) and trying a new set of blades.  I'd also like it to work reasonably well in low wind (as that's mostly what we have here)  and not run so fast as to sound like a helicopter when a storm blows through.

Any ideas?  ;D

 
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: kenl on January 22, 2012, 08:19:32 am
Chris,

 Turned out really nice,, you attention to detail shows. I don't think many people would have come up with 3 WH elements wired in delta, now that's thinking outside the box.

I have a question on your blades. How close to perfect balance are they and how did you go about balancing them? Also what size pipe is your tail boom?

 And again great job!

kenny
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 22, 2012, 09:23:09 am
I'm curious why you believe different blade profiles are more or less suited to MPPT.

Well, MPPT is not a magic thing.  It does is allow your turbine rotor to run at optimum efficiency, and to operate the turbine at very high voltages to improve power transmission efficiency.  A fixed pitch turbine rotor has a Cp curve.  If the blades are designed to run at 6.5 TSR so their efficiency is 35% (meaning they can capture 35% of the total kinetic energy flowing thru the swept area), both above and below that tip speed ratio, the Cp will drop and you will capture less than 35%.  So if you run the blades too fast you'll get less power.  If you run too slow you'll get less power.

So to get the most "bang for the buck" from MPPT it's important to have blades (and a blade profile) that will track the wind speed.  And this means from cut-in all the way to full rated power.  If you run your rotor excessively fast right at cut-in, as is the normal thing to do with a direct hooked machine, you will make less power in low winds than you will if you run the rotor at the proper (most efficient) tip speed ratio.

So let's say the rotor is running at optimum TSR at 8 m/s wind speed, and suddenly there's a gust to 10 m/s.  The TSR of the rotor drops immediately when that gust hits it and it must accelerate immediately (gain rpm) to get the TSR back to optimum.  Blades that have a lot of "meat" out near the tips and outer blade stations do not accelerate well.  They're generating too much drag.  Those blades might work well for low wind cut-in, and they might generate the torque required to lean into a "stiff" generator that "stalls" the rotor as wind speed picks up.  But they are not good for MPPT because it's impossible to make them track the wind speed.  Their tip drag eats up a good chunk their power at higher rotational speeds.  And if you can't turn the rpm, you can't get the volts required to make MPPT work.

One of the things that blew me right out of the water was the fact that I am getting better performance from this turbine from cut-in all the way to 12 m/s, and it beats my bigger direct hooked machines every single day in total energy production, even in lighter winds.  For a long time I argued with Ryan and boB, and whoever else, believing that was not possible.  Well, turns out I was WRONG, and it IS possible - if you tune the turbine for it.  The key to improved low wind performance is not running the rotor too fast.  Forget everything you thought you knew about how wind turbines are "supposed" to work, and throw it out the door.  Then look at how your blades really like to run.  All the homebrew book recipes turn these machines at very high TSR at cut-in  - dead WRONG with MPPT.  I'm cutting this little 3.2 meter rotor in at only 111 rpm.  The Otherpower 10 usually cuts in around 145-150.  So the Otherpower machine does not have enough copper in it to make the higher voltage required for peak performance on the top end, and it's running WAAAY to fast on the bottom end.

To make the Otherpower 10 work good on 24 volt with MPPT - put a 48 volt stator in it.

Edit:  I figured out how to get this off my computer screen using my Picasa program.  For some reason, when the Classic resets its daily logs it sometimes disconnects from my Local Status Panel on my computer.  I noticed a bit ago that it disconnected and reset its daily kWh counter.  So I had to restart the Local Status Panel to get it come back up.  The turbine is putting out about 500 watts this morning.  But what I wanted you to see, VF, is that at only 500 watts output the input voltage is already at 66 on a 24 volt system.

[attachimg=1]

This is how you make MPPT work for you.  If you run it at only 40 volts or something, you're not going to get the most you can get from your MPPT turbine.  I could pull out the logs and take a look at the CSV, but I'll bet the generator is only putting out like 8 amps or so @ 500 watts.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 22, 2012, 09:35:24 am
I have a question on your blades. How close to perfect balance are they and how did you go about balancing them? Also what size pipe is your tail boom?


They were close out of the box, but not perfect.  I static balanced the rotor and it runs pretty nice.  It has a slight problem with dynamic imbalance at around 150 rpm, but above that it smooths right out.  One day, when it's a hell of a lot warmer outside than it is now, I'll lower the tower and have a look at that dynamic imbalance problem (I adjust that with tip tracking).

I don't use pipe.  The tail boom is made from chromemoly tubing - the same thing they make race car roll cages and racing go-kart frames from.  It's 7/8" OD x .125 wall CRM tubing.
--
Chris
Title: Classic Data Logging
Post by: ChrisOlson on January 22, 2012, 05:31:34 pm
This is an example of what the Classic controller can do as far as data logging.  This is an excerpt from the logs over about three minutes worth of run time last night during light and variable wind when the turbine output was changing a lot.  The raw data set is included as an attachment in PDF format and also shows input voltage and current to the controller, logged every 2 seconds.

This graph shows turbine output in watts over the three minute run vs turbine rotor rpm.  It's interesting to see from the graph how fast the rotor is able to accelerate to track the wind speed when it changes and keep TSR at optimum.  During the gust where the power increased to 850 watts the rotor went from 245 to 335 rpm in 2 seconds.  That's why I'm using these blades on this turbine - they can accelerate at that rate, while GOE222's cannot.

Edit:
I don't have my APRS Wind Data Logger tied in with the Classic (yet).  That's on my To Do List.

So I looked back in the wind data from last night during that same 3 minute run and found the wind speed was at 6.3 m/s (about 14 mph) prior to the gust I was looking at to analyze how fast this turbine actually accelerates.  The gust was 8.4 m/s (about 19 mph) and lasted for 3.7 seconds.  The rotor was running at TSR 6.71, and it dropped to TSR 4.94 when the gust hit it.  It took two seconds to get the rotor rpm up to 345 and TSR 6.9 and it was able to run at peak efficiency for 1.7 seconds before the gust died down.

This all may not seem very important, but when you're harvesting energy from the wind you can't just let it slip thru the rotor like that.  Every time you lose out on a gust accelerating the rotor to take advantage of it, you're losing out on kWh production and it all adds up at the end of the day.

Looking at my data, I need to tweak the midrange power curve some more and get the rotor up to TSR 7.1 a little sooner so when gusts hit it, the TSR doesn't drop below 6 before it can accelerate.

That's what data logging, and tuning your turbine for peak performance, is all about.

[attachimg=1]

[attach=2]
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: kenl on January 22, 2012, 06:30:06 pm
Chris,

 Do you feel that the GEO222 profile is not a good candidate for mppt or are you only saying that a profile that can accelerate quickly with the wind is preferred?

kenny
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 22, 2012, 06:42:52 pm
I don't believe the GOE222 profile will work at all well with MPPT.  You're better off with blades that can run at higher TSR and track the wind speed better.  One of the things with MPPT is that generating volts is important.  You can do that with more turns in the generator or more speed from the blades.  Using the more turns method just yields higher internal resistance in the generator and reduced performance.

The GOE222's are better suited to slow turning turbines with a "stiff" generator that needs torque to make power.  That's why they have worked so well on my 3.8 meter 12G turbines.  This MPPT turbine is a whole different ballgame and my choice of blades on this machine is looking better all the time, the more I run it.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: bvan1941 on January 22, 2012, 07:11:54 pm
Chris,
It appears like the 3.2M project is a "breakthrough" in cocepts and a culmination of past mechanical improvements. Seems like you really have a new perspective of the relationship between Rotors and the Classic's operating scheme. If you mentioned the type of blades, I must have missed it. You certainly have earned  the success!
Bill

PS: If this a repeat post ---I'm blaming it on a Senior moment !
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 22, 2012, 07:17:43 pm
Seems like you really have a new perspective of the relationship between Rotors and the Classic's operating scheme. If you mentioned the type of blades, I must have missed it.

Not really a new perspective - just impressed with being able to tune a wind turbine by pressing buttons   :)

I am impressed with the Classic being able to track the power curve as fast as it does.  That's no small accomplishment for wind power.  With solar it's easy because things change really slow.  With wind it's a challenge because nothing happens slow when the wind is blowing good.

The blades are an S809 airfoil.  That was covered earlier in the thread.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: DLoefffler on January 23, 2012, 11:46:30 pm
Chris,

Would it be too much to ask for a material parts list used in the mechanical drive? Specifically, I am interested in type of bearing, spindle, and sprocket size.
As I recall, you are a customer of Tractor Supply.

Your project is of great interest to many of us and we all appreciate you efforts and your generous sharing of ideas.

Thanks,


Dennis
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 24, 2012, 09:19:14 am
Hi Dennis,

Actually, the only parts that came from Tractor Supply are the bearing flanges, which are pressed steel, split flange type.  Sprockets and chain came from McMaster-Carr.  I machined the mainshaft from a forged 4140 chromoly steel billet and hardened, tempered and stress relieved it in my shop.  The mainshaft is not machinable (except with a crankshaft grinder) after heat treating.  The PTO shaft was machined from standard 1" CR mild steel bar stock.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: DLoefffler on January 24, 2012, 12:06:54 pm
Chris, thanks for the reply.

It is my intention to draw this box in solidworks and fabricate same to your dimensions and material list if this is okay with you. I will request from the moderators someplace to put the work as it progresses to it is available, modifiable and thus concise. I have been a follower of RE for years, like you have a farm, machine shop, etc.

Reading the "Other" forum and this, it occurs to me that while there is a tremendous amount of information, much of it maturing, it is really tough to dig out.

The main issue would appear to be liability. If someone else builds it and it fails, whose fault is it? That may indeed stop this project and instead result with many questions of you, a build on my part, but no sharing of knowledge in concise form.

So, first question.

How long is the mainshaft? I have a fairly large furnace, but I am afraid it may not be large enough. Does the shaft have to be supported during annealing and hardening to avoid wrappage?  I am assuming that the shaft was turned from ANSI to ISO as McMaster-Carr supplies the material in ANSI.

I assume the weldment is made before the holes for bearings are bored to avoid warppage issues.

I am looking for the bearings, when I have done more homework, I will come back with the numbers I found and see if they are correct. Asking for all the answers from the teacher instead of working things out for yourself is a poor way to learn.

Thanks,

Dennis

Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Jarrod9155 on January 24, 2012, 02:28:10 pm
Chris ,
    With the goe222 blades you say there not matched well for mppt because of they are better suited for slow rpm and a stiff generator direct tied to a battery bank ??
       You are so right about getting volts from more windings being bad and spinning the blades to fast just doesn't work . In my cases I have wound 4 stator in a year to achieve that perfect match for my mppt setup . You don't touch on adding bigger magnets on bigger rotors can also give you more volts without compromising resistance in the stator . I don't have the math to back goe222 blades right now but kwh that I'm getting from my turbine day to day is becoming very impressive . I been able to keep the tsr at 6.0 through out the curve , I won't lie it has been a challenge but they do work .
     I had Rob Becker right me a tune off some data logging I did for a week and from what I can see from output the blades and generator have exceeded his predictions from his computer program . Maybe if you get the time you will give them a try with the classic .  But great work with the data and right up on the classic .


Jarrod
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 24, 2012, 03:25:08 pm
How long is the mainshaft? I have a fairly large furnace, but I am afraid it may not be large enough. Does the shaft have to be supported during annealing and hardening to avoid wrappage?  I am assuming that the shaft was turned from ANSI to ISO as McMaster-Carr supplies the material in ANSI.

The mainshaft is 260 mm in length.  The shaft has to be rough machined prior to heat treating, then finish it and polish it on the crank grinder - identical to building a crankshaft for an engine.  Although I did not nitride treat the shaft because it has no plain journal bearings on it.

I did not get the shaft material from McMaster-Carr.  I got that from my local steel supplier and I stock various size billets because I build hydraulic cylinder shafts and machine shafts from it all the time.  You could use CR mild steel for the mainshaft but the cross section of the shaft would have to be increased.  The best if mild steel is used is to increase the cross section to better than 50% of what you think is required.  The qualities of CRMO is fairly well documented and proven in applications like engine crankshafts and gearbox shafts.  I use it because I have it, and it's incredibly tough and just about impossible to break a shaft made of it.  But it's not the only thing that can used in this application.

As far as trying to duplicate it, you're on your own.  I've built better than a dozen of these geared wind turbines using this design, and I've showed people how it did it.  But I do not provide "plans" for it, or technical assistance other than what you'll read in a couple forums.  I'm a mechanical engineer by education (and profession for 19 years), and a master machinist.  I have made several "tweaks" to these turbine gearboxes to make them stronger and more reliable in the long term as I've seen things in them that could be improved.  I also tested one to failure on a dynamometer once.  So I know what I got.  I guess the proper term is, "YMMV".
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 24, 2012, 03:43:56 pm
    With the goe222 blades you say there not matched well for mppt because of they are better suited for slow rpm and a stiff generator direct tied to a battery bank ??

Jarrod, that is correct.  What I don't like about the GOE222's is their unpredictability.  I have never been able to stall a GOE222 rotor, and that is bad for a MPPT application where you're going to run it at the raw edge of performance, then try to control it in high winds.

With a grid-tie system you have an unlimited place for your power to go.  With a battery bank you don't.  When the bank is full all the power has to go to diversion (clipper).  If that happens in 70 mph winds I don't want to deal with the raw torque of the GOE222's on a resistive heating load because it's damn near impossible to build a resistive load that will track their power.  Using a blade profile that stalls easily makes it a lot simpler.

I have measured the torque on a small 12 foot GOE222 rotor @ 70 mph to be equivalent to what a small block Chevrolet can put out at full song on the dyno, with that turbine rotor only running at 3.9 TSR.  The harder you load them, the harder they pull because the point of maximum lift on the airfoil moves out closer to the blade tips and it's got more mechanical advantage on the shaft.

Dave Brugge played with them for quite some time on driving resistive heating loads and he tweaked and tweaked, and tried different things, and got a fair match.  But not a perfect match.  Because no matter what you try with GOE222's on a resistive heating load, the day will come when that rotor is only running at 2.5 TSR but the wind is blowing at 90 mph in a thunderstorm, and you will burn up everything in sight because they are impossible to stop.

That's why I selected a blade for MPPT that's easier to control.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dave B. on January 24, 2012, 05:21:35 pm
Chris & Jarrod,

   We all have experiences with the 222 blade. Chris, you hit the nail on the head about a higher speed blade with less torque being much easier to control. The fine line of furling protecting the machine before taking off overspeeding because of a mismatch of the loading on the steeper part of the curve is where the problem is. It just happens too fast with the 222 and unless you are very well stalled before this happens you won't stop it. Overspeed, burnout, crashes you name it I've been there too. 3 complete rebuilds for me to get where I am now charging 48 v safely. I am greatly limiting the potential of my system clipping about 1500 watts max. when the batteries are nearly full. It's frustrating and I plan to look for or carve a set of tapered twisted blades again.

   No fault of the blades, great for their original design and purpose but to scale these up and change both the alternator design and loading has not been the best decision unless you have tons of time, patience and quite likely money to work a very fine line of performance and safety. MPPT can help the experience I'm sure but for the cost of the controller I believe you could purchase a good set of manufactured tapered, twisted blades put them on a fairly standard axial and have a decent performing machine and it would be much easier to tweak in a reliable furling and or clipper to protect it.

  It's very interesting Chris to watch your progress and understand the basics of why you have developed your geared turbines and now pairing it up with MPPT as well is giving you a great tool to work the system. Credit given to the gang at Midnight for the Classic, it can do what it sees to work with but the output to the load intended may require tweaking that the graphs and charts (and programmed load curve) don't always seem to jive with. We all know it's because there are several different loads to consider in the complete system and power is distributed to all of them, all of the time and this is constantly changing depending on the wind and therefore power available. An alternator's effect on the system is also much more complex than just a variable voltage source.

  It sure is fun being part of an elite group who answers and asks questions through experiment. Geared turbines, direct drive, neos. ferrites, battery charging, water heating, MPPT, grid tie, different blade profiles, crashed and burnt up turbines ..... I'd say the 3 of us have a few miles spinning up there.    Dave B.

 
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 24, 2012, 06:15:50 pm
An alternator's effect on the system is also much more complex than just a variable voltage source.

Dave, that's right.  I already burnt up one clipper, that I thought was big enough and I had it all figured out, to a crisp with this MPPT turbine.  When you're working with a high voltage turbine where the voltage is allowed to track the wind (MPPT on battery charging, driving a pure resistive load, or grid-tie), the power on this little turbine can go from 1.8 kW @ 25 mph to 3 kW @ 30 mph in the blink of an eye, before it can even THINK about furling.

And what happens with it is that once the blades go into over-speed (more than 450 rpm) it refuses to furl at all.  And once it refuses to furl and the wind climbs to 40 mph, now I got a real problem with a little 3.2 meter turbine developing almost 10 kW of shaft power with the rotor spinning at 650 rpm.  That was real fun the first time it did it.  And fortunately, the wind died down and didn't sustain 40 mph for very long.  But the thing I don't really like about 222's at that point, is that even throwing the shorting switch to try to stop it is a Smoke Show.

You HAVE to keep the rpm's down on 222's or they'll get away from you.  And once you got the rpm's up so the point of thrust on the rotor swept area shifts to the inside towards the yaw, your generator that was built for 3 kW (or whatever) @ 28 mph with the blades furling normally at normal speeds is as worthless as tits on a boar pig to brake that rotor at 40 mph facing dead into the wind.

At that point you need blades that you can stall easily by pulling them down below their optimum TSR, and GOE222's just refuse to give up once they're lit.  IMHO, they are best suited to slow turning turbines that have a "stiff" generator, aka my geared 12G machines, or on a grid-tie system with an induction generator where they run at constant speed to maintain freq to match the line.  With the awesome torque they can make running at very low TSR, they would be dynamite on a constant speed induction generator grid-tie setup, IMHO.

Marcellus Jacobs, as he was preparing to climb a Jake tower at age 71, told his son Paul "you can't learn anything about wind power on the ground".  Well, you can't learn anything about wind power sitting in front of a computer and drawing pictures and simulations of it either.  You have to build 'em and fly 'em.

This MPPT project had a pretty steep learning curve to it.  You can do all the calculations and simulations and stipulations that you want.  And you can look at your figures and see that there's 27 kW of power flowing the swept area of a ten and a half foot turbine @ 40 mph, and you go "Ho Hum big whoop, ya' know"?  But when you got that little ten and a half footer on the tower, spun right the frick up to 650 rpm and pumping out 9+ kW your indifference at all the numbers that you looked at earlier turns into "HOLY S^&T!!!"
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: rossw on January 24, 2012, 06:31:16 pm
But when you got that little ten and a half footer on the tower, spun right the frick up to 650 rpm and pumping out 9+ kW

I don't think I've got enough loads anywhere to tame that.
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 24, 2012, 07:26:43 pm
I don't think I've got enough loads anywhere to tame that.

In a real short time all these wild thoughts go thru your head, like "why didn't I build a resistor out of 1/2" bolts instead of these frickin' springs?"

If you think I'm nuts you should see what DaveB did once.  He had a machine with GOE222's on it that was making way too much power in a wind storm and the generator was starting to smoke.  His solution?  Reduce the swept area by using the tower as a hacksaw to shorten up the blades.   ;D
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Jarrod9155 on January 24, 2012, 07:42:23 pm
  Chris , 
     I'm laughing reading why your not using the 222 s . At first  I thought you didn't think 222s were up to mppt do to performance limits !! 
         If I could afford or carve a  diffrent set of  6 meter blades I probaly would but it is all I have right now , Your right there like a pitbull (  222s)  you don't know when there gonna bite you . My best story is when at work my wife called and asked if she could shut the turbine down in 40 mph gust . I said sure but after she hit the brake or short it didn't stop !!!  Second to that I had a bearing locked up solid  could not even turn by hand decided to raise it back up till I could install another set bearings . I thought that was as good as a brake a day later 40 plus mph winds came throw next thing I know it look like transformer blowing up when the magnets chewed through stator I just cast in westin epoxy that cost me  150.00 $ in just resin . It's all fun learning the hard way !!!

Jarrod

Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: philb on January 24, 2012, 08:08:56 pm
That's quite a turbine you have Chris.

I agree the GOES222 are almost impossible to tame. I was thinking about some type of blade feathering mechanism to help in a last ditch effort. It's on my long to do list.

The S809 airfoil is used on very large turbines, IIRC. 
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 24, 2012, 08:11:06 pm

     I'm laughing reading why your not using the 222 s . At first  I thought you didn't think 222s were up to mppt do to performance limits !!

Jarrod, I'm not saying it can't be done.  Just that it's not a good choice.  The blades DO have to be able to track wind speed quite well, and the GOE222's are better suited to low TSR.  It's hard to capture 35 or 36% of the wind power flowing thru the swept area with low TSR blades.

Note to DaveB:
You know - the more I think about your method of emergency power control for GOE222's, the more I like it better than this variable pitch BS, or throwing a rope at the turbine to try to tangle it and stop it.

Why not just build the tower with a EPRS (Emergency Power Reduction System) right in it?  If you have a runaway in the Big Wind and your GOE222's get away from you, Standard Procedure is to rush out to the tower and pull the EPRS Actuator Cable.  This causes a huge spring loaded saw blade to swing out from the tower and whack 3 to 4 feet off the turbine blades.

That would be really cool    ;D
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dave B. on January 24, 2012, 09:50:05 pm
  My 18' ended up as patched up 16' wall art. The crack against the tower echoed through the trees behind me like a shot. Those blades were way too flexible for the amount of clearance I had to the tower and especially at high speed and quick yawing. I figured a couple feet was plenty, I bet for a 9' blade it could have flexed 3'. Flexing without breaking might be a good thing but not if they hit the tower.

  The blades I threw the towel at were my own 12' I carved and were on the 10' test tower. Funny how I thought a floodlight hanging off the power cable would be a good load while I took a quick trip to the hardware store after just getting everything up and mounted to test. Murphy's Law, big winds came out of no where while I was gone and when I came up the driveway it was just getting dark. Imagine a snake thrashing around to rid itself of a light sabre on it's tail throwing a spot all over the woods and then the overspeed screaming of the blades with it's yawing madness and there you have a monster with a deserving role in a Steven King movie. Several tosses at the center of the hub with a big wet towel the best I could tamed the beast as the wind eventually let up also. I bungy corded the snot out of that thing to the tower and went inside traumatized. It's still got to be the best story I have, that was nearly 8 years ago.

  All fun stuff and fun to share. It's like flying though, mistakes can be serious without proper respect. Be aware and stay safe !    Dave B.
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: DLoefffler on January 24, 2012, 11:06:04 pm
Thanks Chris,

I appreciate your response as well as the information. It appears as though the community is growing beyond trailer axles and crashing blades against towers, although I have enjoyed the pictures and the sense of camaraderie evidenced by same over the years. Your pictures are great, but for many of us, putting it all together needs to begin somewhere. I am not a mechanical engineer, but an applied math grad of Madison, with some machining under my belt as well as a complete machine shop. I can hold my own. Thus, it seemed like a good starting point to place some basic plans out, have others build off of them, see what modifications need to be made and grow as a community. Probably naive. I greatly appreciate what you share, understand the learning curve we all go through and I will go through.


Forums are great, enjoyable, but they seem to drift off topic and become enjoyably anecdotal. It might be an interesting idea to have a base off of which to build wherein various contributor state, "I have used these bearings and they are great, or they fail in this application." You are taking this endeavor to a new level with great engineering, machining, and fabrication skills.

There are so many mistakes to make, I am grateful you have shared your efforts to reduce ours. Thanks also for the clarification on the main shaft including length. Looking at the pictures, it appeared as though it had been ground, and I was wondering whether or not it was heat treated in a vacuum furnace so as to avoid this issue.
I don't have a crankshaft grinder, now I have a hint of what a tool post grinder might be used for on my lathe.

Again, looking at your pictures and the hints in the kind reply to my quesitons, I assume the bearings being dual races self align to correct for any issues in bearing alignment.


Thanks again, I look forward to your posts.


Dennis
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 25, 2012, 01:33:40 am
Again, looking at your pictures and the hints in the kind reply to my quesitons, I assume the bearings being dual races self align to correct for any issues in bearing alignment.

The dual row angular contact ball bearings actually came from Sweden.  My wife is Swedish and we went to Sweden for Christmas and my father-in-law had gotten them for me because he works for SKF.

Svenska Kullagerfabriken AB invented the self-aligning bearing in 1907.  But angular contact ball bearings are not a self-aligning type bearing.  They got pins in the outer race that engage with notches in the flange.

The bearings I used on the PTO shaft are self-aligning ball.  Those are insensitive to angular misalignments of the shaft relative to the housing.

Again, just because that's what I used, does not mean it's the only way to do it.  If you really wanted to, you could machine bearing cup bores and use tapered roller bearings on the mainshaft as long as you can come up with a proper way to lube and preload them.  You could use self-aligning roller bearings if you wanted to with a needle thrust in the rear of the case, and frankly, if I built a gearbox for a bigger turbine (like 5-6 meters) that's probably what I'd use in it.

For most folks who want to build turbines, using the published "book plans" is the best.  When it comes to geared wind turbines you just can't slap any gear ratio on some blades and make it work.  There's a fine line between trading torque for speed and generator efficiency, and actually being able to get more down the tower with it.  When it comes to building turbines you're either the type that needs plans and specs to follow, or you understand the concepts and can take it from there.  If you're the former, trying to build one of these machines like I build is just not the thing to do.  If you're the latter, then you immediately see what makes it tick and why, and you'll use the idea to design your own machine.

Trying to duplicate this one right down to the last dimension, is not going to work for you unless you understand some of the mechanical aspects of the thing.  That 46 lb flywheel mounted on rear the gearcase spinning at over 1,000 rpm has a HUGE inertia moment, and it makes the machine a little more quirky than I'd like.  It tries to counter the precession force of the rotor, which is part of the reason the machine won't furl when it gets wrapped right up.  I de-rated the machine to "fix" it.  But on the next one I'll fix it mechanically.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: DLoefffler on January 25, 2012, 01:05:24 pm
Thanks, more questions.

Axial force for a 3KW machine. My rough calculation is that the maximum force would be slightly less that 700 lbs axially assuming all the force of the turbine is directed that way. Design with a 3x margin and a 2100 lbs axial bearing should fit the bill.

On your shaft, there are no shoulders to seat against the bearings. How is the axial force transmitted to the bearing?

For the taper on your shaft, matter of curiosity. Taper attachment for the lathe or offset the tailstock?

My lathe has a tracing attachment, but I have never used it, nor have I installed it. It is a ROMI and unfortunately only a 14" which may or may not make turning the plates an issue. I am considering mounting the plates on the mill turntable, surface milling the faces and milling the edge with the turntable. Probably not as smooth as a lathe. Farming the job out would be an option, but none of us on this board would do that except under the most extreme circumstances. :)

Dennis
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: FrankZappa on January 25, 2012, 02:01:24 pm

My lathe has a tracing attachment, but I have never used it, nor have I installed it. It is a ROMI and unfortunately only a 14" which may or may not make turning the plates an issue. I am considering mounting the plates on the mill turntable, surface milling the faces and milling the edge with the turntable. Probably not as smooth as a lathe. Farming the job out would be an option, but none of us on this board would do that except under the most extreme circumstances. :)

Dennis

Sometimes you have to get creative. Just slow things down a bit.

Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 25, 2012, 02:22:28 pm
Axial force for a 3KW machine. My rough calculation is that the maximum force would be slightly less that 700 lbs axially assuming all the force of the turbine is directed that way. Design with a 3x margin and a 2100 lbs axial bearing should fit the bill.

I don't know where you got them numbers from, but it's not even CLOSE.  To get a 700 lb axial thrust component on a 3.2 meter (10.58 foot) swept area would require a pressure differential of 8 Psf.  You can only get about 2.3 Psf with a sold sheet of plywood with a Cd of 1.05 in the wind up there @ 30 mph.

The actual axial thrust component @ 13 m/s and 3.5 kW shaft power is 32.7 kg.  That's working on a 130 mm offset and gives a torque moment at yaw of 47 Nm.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: DLoefffler on January 25, 2012, 07:58:11 pm
Chris,
Well, I embelished a bit, I actually spent more time in theoretical math than applied, but I did survive diffq - was actually in the grad program. We really didn't do a lot with numbers, sort of "banal". :)

I appreciate the advice regarding the corn, there is a field road with a 'Y" and if I had the coop remove the power ines and go underground, a free standing would work;  of course, would have to program the route into the combine prior to harvest.  :-\

Talk is cheap, I have a hell of a lot of work to do. I plan on starting on the gear case first, build one, see how it goes, one piece at a time.

Look forward to future exchange of ideas - mostly yours as I don't have many worthy of mention at this point.

Dennis
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 25, 2012, 09:26:47 pm
Well, I embelished a bit

Dude - I'm an engineer so I never passed English class.  Don't even know what "embellished" means.   ;D
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: tomw on January 25, 2012, 09:39:28 pm
Well, I embelished a bit

Dude - I'm an engineer so I never passed English class.  Don't even know what "embellished" means.   ;D
--
Chris

Try "exaggerated".... 8) ;D

Tom
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on January 25, 2012, 09:49:09 pm
Try "exaggerated".... 8) ;D

Well, you just have to be patient with me so I understand.  It's kind of like the story where the two engineering students were walking across campus when one said, "Where did you get such a great bike?"

The second engineer said, "Well, I was walking along yesterday minding my own business when a beautiful woman rode up on this bike. She threw the bike to the ground, took off all her clothes and said, "Take what you want."

The second engineer nodded approvingly, "Good choice; the clothes probably wouldn't have fit."
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Nekit on February 14, 2012, 06:56:34 am
Chris,
Just curious, what kind of kwh for the day are you getting with this setup.  Very nice work.

Rob L
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on February 14, 2012, 10:09:32 am
On a good day with a full 24 hour run in nice wind, 20 kWh.  On a poor day, zero.  It's averaged 6.1 since I put it on the tower.

The best continuous run it had so far was just last week - 20 kWh on Thursday, 13.6 on Friday, for an average output of 700 watts/hr for 48 hours.  Average wind speed for the 48 hours, as recorded by my APRS Wind Data Logger, was 7.9 m/s (17.9 mph).  Peak output for the 48 hours was recorded on Thursday at 2,334 watts.

During the same 48 hours one of my 3.8 machines also on a 74 foot tower generated 29.8 kWh, for an average output of 617 watts/hr.  Peak output of the 3.8 meter was also on Thursday at 2,116 watts.

It pretty much walks all over the bigger direct-hooked machines when the wind blows good, and it holds its own against the bigger ones in lighter winds.

The thing with these homebrew turbines is that the bigger they get, the less efficient they are.  I have calculated the overall efficiency of this little 3.2 meter at 29.8% @ 12.5 m/s.

The design of the generator in these homebrew turbines does not scale well with swept area.  For instance at 12.5 m/s @ 1,000 ft elevation you have ~24 kW of power flowing thru the swept area of a 17 foot machine.  At 30% efficiency it should be delivering ~7.2 kW.  The problem is, the generator can't take it.  The Mountain Boys that came up with the "Otherpower 17" might be able to get away with the weak-kneed design in their thin air.  But you put those machines on a real wind site @ 1,000 ft elevation with nice dense air flowing thru it @ 25-30 mph, and I'll push that 17 to 7 kW continuous and turn it into a flaming wreck.  That's why I have continued to shy away from larger turbines.  I have real air and real wind, and I don't need that kind of swept area to make power.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: bvan1941 on February 16, 2012, 09:33:19 pm
Chris,
Are you still using the "Powermax" S-809 blades for your  3.2M ? If not, who else makes them?
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on February 16, 2012, 09:45:04 pm
Yes, they are for PowerMax upwind and Talon downwind turbines.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Bio Diesel Man on February 27, 2012, 09:00:09 pm
Hi Chris,    I have been reading your post lately and am very interested in your wind turbines design. Was wondering why you use stainless steel roller chain,,,,Is it for wear and chain stretch,or for some other reasons?Also was wondering what kind of oil you recommend in the gear case and the viscosity of it?? I am new to this forum, and am very interested in building a ferrite magnet wind turbine using C8 ceramics,1 1/2 inches wide by 4 inches long and 1 inch thick. I am thinking about a 3 phase machine with 16 pole pairs and 12 coils. Was also thinking about making wood blades like they do at Otherpower.com..Are blades like that OK for a ferrite magnet wind turbine. I also am a welder fabricator by trade,and have 2 lathes, a bridgeport. large drill press, ect. Also was wondering if a chain tightener with spring tension might be good  for keeping the drive chain tight??  Lots of questions!!!! I really enjoy your posts and your videos too.. Thanks,,  Duff Streeter,,Bio Diesel Man
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on February 27, 2012, 09:29:02 pm
The stainless chain wears less than regular steel chain.  Where the chain wears in in the link side plates and pins.

I just dump in whatever oil I find in the shop.  Anything that keeps the chain wet works.  I've used gear oil, 15W-40 diesel oil, hydraulic oil, and I even dumped diesel fuel in one.  The one with diesel fuel in it has been running for over two years.

Yes, wood blades work fine with ferrite generators.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Bio Diesel Man on February 28, 2012, 08:33:19 am
Hey Chris Thanks for your reply. I really appreciate you and all your work..  I was wondering if the C8 ceramic magnets that I want to use are a little stronger than the ferrite blocks you are using?? Are your blocks C5 or C8??  Also I am thinking about covering the wood blades with fiberglass,then paint them .Would you recommend doing something like that to protect the blades from the harsh weather we have here in northeastern Michigan??  I to am an old farm boy and have lots of experiance with equipment and chain driven devices..How long do you think a chain driven unit will last as far as gear wear, chain wear or stretch?? And was wondering about putting a chain tightener inside the chaincase,that is spring loaded to keep the drivechain tight?? Do you think that is necessary and could you use a sprocket with a bearing assy. that you could get from McMaster/Carr or Graingers or MSC ind. supply??Lots of questions,, but just trying to think everything through before I start cutting and welging things together..Thanks so much!!  Duff Streeter
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on February 28, 2012, 09:49:03 am
Wood core blades, with fiberglass overlay?  I don't know much about that, really.

A tensioner is not necessary.  An oil bath chain drive is much like that in the Detroit built V-8 camshaft drives used for better than 6 decades.  The shaft spacing is so close that there is no "stretch" in the chain.  What ultimately wears is the link side plates and pins and when the backlash becomes excessive, simply replace the chain, which is a half hour job once you have the tower laid down.  I have over 80,000 hours of combined tower time on several turbines using this drive and I have yet to have to replace one, or even see the backlash increase from what it is set at during assembly.

To put it in perspective, look at how long the timing chain lasts in an engine at the extremely high speeds it runs at.  A wind turbine, at full power, barely runs at cranking speed of a V-8 engine.  And the main point of failure in the timing chains used in V-8's for years and years is not usually the chain - it's the plastic teeth on the cam sprocket (that they use to make them run quieter).

You never want to try to "fix" something that has proven itself over decades, and millions and millions of hours in many different applications, to "just work".
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Bio Diesel Man on February 28, 2012, 08:58:25 pm
Hi Chris,  Thank you for your information..I am glad there are people like you out there that are not afraid to try new things.. That is kind of the way I look at things too.As I go along with this project I will let you all  know how I make out.I do have a 100 foot ss100d90 Rohn tower I am working on getting it ready to put up. I am going to hinge the tower 40 foot up off the ground and lower the top 60 foot to ground level for working on my wind turbines.. I have a large pad of reinforced concrete poured with a large winch mounted to it that  I will use to raise and lower my tower.. If you are interested in it let me know and I will go into it further..  Thanks for your help.. Duff streeter,  Bio Diesel Man
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Bio Diesel Man on March 06, 2012, 10:11:22 am
Hey Chris,    Just was wondering what you use to glue your magnets to the rotors.Do you use a special glue like you can get from Adams Magnets,or do you have something else you use.  Thanks, Duff        Bio Diesel Man
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: birdhouse on March 06, 2012, 11:27:40 am
duff-
i fiberglassed my wooden blades.  first i stated with blanks made from eight pieces of clear fir glued up with gorilla glue.  carved the chainsaw style, then glasssed them with 6oz and west systems.  then, coated with two part epoxy paint.  they turned out beautifully, and i believe they will last a very long time.  when most folks see them up close they don't even think they're made mostly of wood. 

adam
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Bio Diesel Man on March 06, 2012, 03:19:46 pm
Adam,   That is awsome,, I am glad to hear you have done it and they are working out for you,as I was thinking alone those lines to.It seems like the fiberglass covering would be the cats meow!!!!  That way you get real nice blades at a reasonable cost..  Thanks, Duff  Bio Diesel Man
Title: Type of adhesive to glue ceramic magnets to rotor disks
Post by: Bio Diesel Man on March 07, 2012, 11:25:06 am
Just wondering if anyone out there building axial flux turbines is using a special glue to fasten the magnets to the magnet rotors?/ Has anyone used JB Weld, and does it work, or should I use something else?/   Thanks for this great forum..  Duff   Bio Diesel Man
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on March 07, 2012, 03:21:05 pm
I use JB Weld and have never had a problem with it.  But I also pin the neo gen mags and use "claws" on the rotors on the ferrite ones to hold the mags against excessive centrifugal forces.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Wolvenar on March 07, 2012, 07:32:57 pm
I would be a bit leery of JB weld on Neos. its a friggen MESS, and tough to keep where you need it.

JB weld has metals that the mags will pull around a bit like very thick ferrofluid.
I am not sure if this has any measurable effect on the flux, but either way it can just be a pita.
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Bio Diesel Man on March 07, 2012, 08:47:37 pm
 :)Hey Chris, Thanks for the info. on the JB Weld,as I am laying out a chain driven oil bath unit, similar to   yours,, using ceramic C8 magnets.. I am going with magnet rotors  of 20 1/2 " in dia. and may use a third   bearing assy. out back behind the magnet rotors because of the weight of the disc.They are 1/2 " thick,so the generator assy. will be pretty heavy..Also plan on extending the shaft and bearing assy. out front where the blades connect to the turbine to allow for tower clearances.I am using a Rohn 100 foot tower and the top section of the tower is aprox. 21 " across from each leg..So I am concerned with blade to tower clearances..Any other feed back is always great too...    Duff,  Bio Diesel Man
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on March 07, 2012, 08:49:41 pm
Duff, tip the rotor back about 8 degrees.  That's what I've been building into my heads and it provides about 2 feet of clearance on a Rohn SSV tower.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: rossw on March 08, 2012, 01:14:43 am
I would be a bit leery of JB weld on Neos. its a friggen MESS, and tough to keep where you need it.

JB weld has metals that the mags will pull around a bit like very thick ferrofluid.
I am not sure if this has any measurable effect on the flux, but either way it can just be a pita.

I had an oopsee moment with jbweld. I had a bunch of magnets (1/4" round 1/2" long N42) that I needed to attach to the tops of aluminium frame doors.

I mixed up JB weld, put a nice big dob in the require spot, nestled the magnet in it and moved on to the next.

It was a miserable failure. The magnet pulled most of the JB-weld up and around the magnet. Very little actually stuck to the aluminium. I worked - sorta. But nowhere near as well as I had expected!
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Bio Diesel Man on March 08, 2012, 08:04:58 am
 8)Hi Chris,  That is what I was thinking about .But wasn"t sure if just tilting the rotor back on a tower like mine would give me enough blade clearance..Do you think I should use another bearing assy. behind my generator head as it will be made from 1/2 " plate for the magnet rotors and they are 20 1/2 " in diameter,to allow for 16,,,  1 1/2 " wide by 4" long by 1" thick ceramics on each disk..  I will be using either 1 1/4" or 1 1/2 ' dia. shaft stock for the gear driven unit. Hope this is heavy enough.. Just wanting your input if you get time.. Duff   Bio Diesel Man
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on March 08, 2012, 11:31:13 am
..Do you think I should use another bearing assy. behind my generator head

Truthfully I don't think you need a pilot bearing on there.  An 1 1/2" bearing will handle as much radial load as the axle bearings in the rear axle of a 1/2 ton pickup truck.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on March 08, 2012, 11:33:54 am
It was a miserable failure. The magnet pulled most of the JB-weld up and around the magnet. Very little actually stuck to the aluminium. I worked - sorta. But nowhere near as well as I had expected!

Ross, I could see where that would be a problem on aluminum.  But I've built better than three dozen turbines using JB on the mags and never had a single problem with it - unless I wanted to get some mags off some plates later.  With both JB Weld and pins in the center of the mags it's about impossible to get them off without breaking them.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Wolvenar on March 08, 2012, 03:03:50 pm
Question Chris.

Does JB weld work differently on ceramics?
I've also tried it on neo mags, and had the same experience as Ross.
It migrates most of it to the sides of the mags and corners rather quickly, WAY to fast to set up.
Like I said it looks like a very thick ferrofluid experiment.
Are the ceramics just weak enough that it does not do that?
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on March 08, 2012, 03:49:51 pm
Does JB weld work differently on ceramics?
I've also tried it on neo mags, and had the same experience as Ross.
It migrates most of it to the sides of the mags and corners rather quickly, WAY to fast to set up.
Are the ceramics just weak enough that it does not do that?

No, it'll do the same thing on ferrites.  You're putting too much on there.  All it takes is a very thin film of the stuff applied evenly to the surface of the magnet that goes against the rotor.  If you put too much on the magnet will "swim around" on it and the shear force of attraction between the magnet and steel forces it out the edges.  You want to put enough on so it does squeeze out and seals the magnet from getting water under it.  But it's a case where too much ends up being a mess.

Also, I machine my rotors so they're really rough on the magnet side so the JB Weld has something to "bite" on to.  Putting the magnets on a perfectly smooth surface might work, but then you're going to have to use a lot less of the epoxy because virtually all of it will squeeze out the sides.

If nothing else, rough the discs up severely with a disc grinder.  I cut them on the lathe with a fast rate on the cross feed so they almost got "threads" in the surface of the disc.

Neo rotors with pins are easy because once you put the magnet over the pin it stays put while the JB Weld sets up.  The ferrite rotors with those big blocks are a pain.  Just because they're ferrites doesn't mean you can't get your fingers pinched and suddenly have a magnet get sucked off the plate by one that's adjacent to it, suddenly flip upside down in mid-air and go "SMACK" on top of the other one.  I got sick of that and cut out a template made of UHMW poly to hold those ferrites in place while the JB Weld sets up.

Those 16 pole rotors with the 2 x 2 x 1" thick ferrite blocks are more dangerous than the 12 pole neo rotors with 2 x 1 x .5" thick neos.  The total attraction force between those 16 pole rotors is more than it is with the 12 pole neo rotors.  So you have to be careful with that during assembly.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ghurd on March 09, 2012, 10:10:04 pm
JBWeld give me fits.
It crawls all over everywhere.
If it is a situation like a motor conversion that requires magnets to be set over several days or a week, then it requires 5 hours of babysitting to be safe.  A glop of JB in the wrong place, at the wrong time, is a serious mess.
I do use it again, mostly, but only place magnets when I have 5 hours to check it every 10 minutes for 5 to 8 hours.
Just when you think it won't crawl any more, and you go to bed, the stuff makes a pool in the worst possible place.
I have thrown things away after the glob showed up where the thing was not salvagable.

It sticks well if the surface is clean.

If the neo's nickel plate is damaged (IE: HD neos), then the plate pulls off the neo.

"Pins and Claws" weaken the magnetic field. You yourself proved it with the paper clip test.
(might try looking at the physics of a old-school fridge magnet hook, because we are correct about it, even if you don't get it... and it follows the exact same concept as your comment as Ross' magnets on AL).
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dale S on March 10, 2012, 06:45:59 am
Boy! Somebody got his corn flakes peed in, are veiled personal attacks by moderators allowed on this board?
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on March 10, 2012, 07:29:17 am
"Pins and Claws" weaken the magnetic field. You yourself proved it with the paper clip test.

That's only in theory.  My gauss meter shows no difference in the air gap, and a spin test (rpm/volt) shows no difference with pins or claws, or without.  So in practical application, if somebody asks me if they can do that I'm going to tell them yes because I have tested it and it works fine.

I have built a lot of turbines and tried a lot of different things.  Theory is fine.  But there's a difference between what theory says you SHOULD do vs what you CAN do.  Only experience tells you what you CAN do.  Experience tells me that using JUST JB Weld is not going to work if there's any significant shear or tensile load on the adhesion point.  Adding pins or claws allows me to spin very heavy axial generator assemblies at speeds never before attempted in homebrew turbines without affecting rpm/volt.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Wolvenar on March 10, 2012, 08:23:52 am
Quote
Boy! Somebody got his corn flakes peed in, are veiled personal attacks by moderators allowed on this board?

@Dave  or anyone that might have actaully seen it this way

Hoping to diffuse this early just in case there was something serious about that comment

Just because ghurd has a "title" doesn't mean he wont have an opinion.
Heck not even sure if he remembers that he has that "title", everyone has been so civil so far here moderation has not been needed for anything but improving the forum look and moving a couple topics here and there.

These titles can become a hampering thankless job, as has been seen elsewhere.
Many wish not to have a title at all, just so they can contribute something that may not be well taken, without feeling they are in some way going to cause the forum problems if someone has a problem with it.

Lets not have a  "them against us" thing happen here..
Lots people have had different experiences for who knows what reasons.
It can give us all different views based on different experience or training.

Were all people with a passion for RE, and long as we can all keep it civil,
agreeing to disagree should happen time to time.

Please continue with our regularly scheduled programming

Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: tomw on March 10, 2012, 09:17:13 am
Boy! Somebody got his corn flakes peed in, are veiled personal attacks by moderators allowed on this board?

Dale;

People will be people but, no, attacks are not acceptable. "Veiled" is a judgement call. I often make comments to folks I know well that may appear to be attacks to an outsider.

I guess I am thick today? I don't see that. PM me with the details and I will look into it closer.

Thanks.

Tom
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on March 10, 2012, 02:42:36 pm
Guys, the comment about
"might try looking at the physics of a old-school fridge magnet hook, because we are correct about it, even if you don't get it..."

may be interpreted several ways.  I've built enough turbines to have a general idea of "how it works".  The concerns with using pins in magnets, or claws on the outside of the rotor, to retain them against centrifugal forces are only founded in theory.  I have done enough testing, and built enough turbines, to know that it does not make any difference in gap flux or rpm/volt performance of the generator whether you have them on there, or not.

What will make a huge difference in gap flux is if you DON'T use a method to retain those magnets to the rotors and they decide to leave the general vicinity of the generator when it is spinning at 1,000 rpm.  That causes a huge loss in power, and subsequently (usually) a runaway turbine.

JB Weld has a fairly low tensile strength and when you're using it to install magnets on rotors it pays to calculate the stresses on the magnets on the rotors before you rely on it to hold them in place.  With these big heavy ferrites at .77 lbs each on 355 mm rotors the tensile strength of the epoxy is exceeded at only 233 rpm.  On this particular turbine it would not even reach cut-in before the magnets fly off.

Take a look at this generator on a 12G turbine with all those "claws" on there to retain the mags:
[attachimg=1]

The guys that are embedded in theory are going to see that, choke on their beer, cough and tip over in a coma because it "won't work".  Those of us who hands-on build it know that it does work.

So I might not "get it".  But I DO know how to build wind turbines that work.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Wolvenar on March 10, 2012, 05:41:30 pm
Just want to point out.. Zubbly put it to me once, "If it gets the job done, why care if it's not theoretically perfect."
Take a look at his conversions, he has some of these not so perfect things going, and they work.
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: rossw on March 10, 2012, 06:01:37 pm
Take a look at this generator on a 12G turbine with all those "claws" on there to retain the mags:

Chris - I'm often a stickler for details, but as Tom says, sometime "just good enough is all it needs to be".
I think this MAY be one of those. Where you may be losing some theoretical power, but in the greater scheme of things it makes no difference.

I'm curious if you ever considered using something non-ferrous for those claws? Like brass?
Sure, you probably can't just grab the MIG and whack 'em on, but the blue spanner will do it :)

Or, is the extra effort simply not warranted in your experience?
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on March 10, 2012, 06:22:16 pm
Or, is the extra effort simply not warranted in your experience?

It's just that the extra effort isn't warranted.  Some guys put a non magnetic stainless band around the outside.  When I started fiddling with these ferrite generators I had one fly apart during testing.  I tried to drill the mags with a cobalt drill for pins and couldn't even make a scratch in the surface of the magnet.  Neos can be drilled.  Ferrites require diamond cutting tools.

So I contacted Hugh and Flux and asked them if they'd ever tried "claws" on one.  Neither of them had, and both said it would cause problems with low voltage.  Just because somebody says you can't do it never stopped me before.  So I started experimenting with it.  I found not even one tenth of a volt difference with or without, and my gauss meter showed .17 mT in the airgap no matter if I had them on there or not.

Hugh and Flux and I discussed it at length and the conclusion put out by Flux was (after watching my movie I made on it):
Certainly steel screws and roll pins in the holes of neos will have no ill effect, using stainless may be convenient but is not necessary.  In the second case the disc should act as a conductor of the flux from one magnet to the other and in theory there will be no flux on the back of the disc. I think it unlikely that 2 such size ferrite magnets will saturate 1/4" thick mild steel with the other poles open circuit. Probably away from the edge you would detect little. It is really a case of how much here, I suspect the leakage needed to support a paperclip is not measurable on the gap flux by fluxmeter of by volts induced in a coil so it is safe to ignore it.

There is significant leakage flux with the wide air gaps of these dual rotor machines which you won't avoid and some tinkering with the path of these leakages will have virtually no effect on the real gap flux.


Been doing it ever since.  We arrived at the conclusion that all the "claws" do is redirect flux that was otherwise leaking anyway.  It don't change anything in the air gap where the work gets done.
--
Chris

Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dale S on March 10, 2012, 07:29:58 pm
So Flux doesn't get it either. ;)
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on March 10, 2012, 08:04:34 pm
So Flux doesn't get it either. ;)

Well, I don't know about that.  It didn't do what everybody expected.  The thing with flux is that you can't see it.  You can attempt to model it in different ways.  But the one thing that nobody considered is how much of it leaks, and by leaking it's not useful.

Hugh's comments on it were (I don't think these guys will mind me quoting them in the interest of education on these machines):
In the first case with one disk and one magnet, the flux is obviously spewing out all over the place and coming around the back in force.  The second magnet traps a lot of that flux and reduces the leakage around the back.  A second disk with magnets would further reduce the leakage and focus flux in the right place, through the coils.

Adding a 'claw' seems to trap flux that would otherwise leak out and around the back.

The voltage is unaffected by the claws, which suggests that either the amount of leakage is not significantly increased, or the edge of the steel disk is saturating, so the extra flux you get in the claw would not otherwise have been available.


So we all learn as we proceed.  In order to learn and make advancements you have to question things.  The greatest advancements in technology and knowledge were not made by people who blindly accepted that the earth is the center of the universe and everything revolves around it.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: MadScientist267 on March 13, 2012, 09:42:02 pm
Not to throw any gas on any fires here or anything, but the one thing that did raise an eyebrow with me was about the pin in the center...

While that may not have any significant effect, I would tend to think that there is effectively some "shorting" happening in that scenario. How much it would affect real-world flux patterns, well, I couldn't really say.

I think the idea though of problems stemming from the "claws" are more rooted in the demonstration provided by things like hard drives. The magnet for the servo is insanely strong, yet sits right next to the edge of the platters, one of which contains "irreplaceable" information about the drive, right at the edge. Hard drive designs would appear MUCH different had there not been a way to keep all that flux contained within the servo for only the voice coil to see, but there it regularly sits, typically within 1/8" of the ever so delicate data.

That said, it's likely a case of "classic misunderstanding" where things are only "black and white" and not in shades of grey. So since it happens there, it must happen everywhere else too.  ::)

Which, as you pointed out, is obviously not the case.

My $0.02

Steve
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dale S on March 14, 2012, 09:57:40 am
The important thing to keep in mind here is this machine produces a crap load of power, a few miliwatts one way or another is virtually meaningless.
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: oztules on March 14, 2012, 05:54:44 pm
Steve,
Your right. The rules are unbendable. The laws of the universe are black and white..... whats different is how we use things.

The axial flux alternator is the absolute pits when it comes to using the flux sensibly. It is one compromise after another. But it is easy to build, and we can throw heaps of magnet at it. With neo, that is all it takes to make it work very very well.

With ferrite, it becomes obvious how bad the design is, as without Chris's gearbox, it is next to useless. With his 130cubic inches of ferrite, you can easily make a very very powerful alternator at direct drive speeds. The AWP uses less than 90 cubic inches of ferrite, and makes an easy 2kw direct drive..... but it is not axial flux. It uses the flux more wisely, and as such is very very much better at generating power at very much lower rpm..... downside is it is not possible to build at home unless you can find stampings..... so thats out.

Knowing how bad axials use flux, and knowing all flux lines leave and return..... well if we aren't using them then they are leaking all over the place. If we used half of the flux we would be going very well. so losing flux at the back edge will mean nothing in the scheme of things.

Another reason why shorting flux on the outside does nothing bad for this design can be seen by just looking at the geometry of the coils and the placement of the mags. It would appear that the outside edges of the mags are never going to contribute any emf, as the coils windings under them are running not perpendicular to any field, but parallel.... so if you short the field, they won't know anyway... ie the electrons in the wire are being displaced from side to side not along the wire, and will contribute no emf to the output. So no surprise that he could not measure any meaningful difference............but the tabs hold the mags on... and thats a good thing, and they are only shorting non-useful flux... thats a don't care thing...... and it still works... and thats a great thing.



.................oztules
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Wolvenar on March 15, 2012, 03:55:24 am
Oz-- 
Thanks for pointing out that the edge is not crossing any wire at an angle that makes any difference.  I had always had that thought, just a little skittish to open my mouth, as I insert my foot often enough.
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: MadScientist267 on March 15, 2012, 10:28:30 pm
<-- Opens his mouth and inserts the foot on a regular basis...

But.. That was a very well thought out explanation... and does make sense...

More than one way to skin a cat... or so I'm to understand.. ;)

Steve
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Bio Diesel Man on March 24, 2012, 11:03:47 am
Hey Chris,  Could you give us some idea how much you would charge to build a 3.2 ferrite magnet wind turbine ? And would that include anything like the rectifier too?/  Just wondering if that might be  better than making one?/  Thanks, Duff  Bio Diesel Man
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dale S on March 24, 2012, 01:03:19 pm
Check his website, it's all on there.
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: tomw on March 24, 2012, 01:43:23 pm
Check his website, it's all on there.

Dale;

Who are you responding too and what website might be good info to include.

If Chris has a website I never saw (or remember) a link? It appears in order after a request for info from Chris on building a turbine for someone.

Just saying...

Tom
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Dale S on March 24, 2012, 04:30:27 pm
I thought he had it in his sig line or on his profile.

[Edit] Link removed.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on March 25, 2012, 11:27:26 am
Hey Chris,  Could you give us some idea how much you would charge to build a 3.2 ferrite magnet wind turbine ? And would that include anything like the rectifier too?/  Just wondering if that might be  better than making one?

I don't typically like to advertise on forums and such because the forums are for homebuilders to build their own turbines.  If you want information on a turn-key machine please either email me or send me a PM and I'll get the info to you.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: tomw on March 25, 2012, 02:18:12 pm
Hey Chris,  Could you give us some idea how much you would charge to build a 3.2 ferrite magnet wind turbine ? And would that include anything like the rectifier too?/  Just wondering if that might be  better than making one?

I don't typically like to advertise on forums and such because the forums are for homebuilders to build their own turbines.  If you want information on a turn-key machine please either email me or send me a PM and I'll get the info to you.
--
Chris

Chris;

Well, you sell useful parts as well so I see no problem with a .sig line or link in your profile "website". I would encourage it, in fact.

Not like you came here just to pimp your site.

Just my opinion.

Tom
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: rossw on March 25, 2012, 05:41:49 pm
...so I see no problem with a .sig line or link in your profile

and

Not like you came here just to pimp your site.

Just for the record, I agree with Tom. There's a HUGE difference between joining up with the (obviously) express purpose of pimping your stuff, and what you've done - contributed, participated, got some "runs on the board" as it were - and then offering your stuff - especially when others have asked for it, rather than you "pimping" it.
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Watt on March 25, 2012, 09:44:22 pm
...so I see no problem with a .sig line or link in your profile

and

Not like you came here just to pimp your site.

Just for the record, I agree with Tom. There's a HUGE difference between joining up with the (obviously) express purpose of pimping your stuff, and what you've done - contributed, participated, got some "runs on the board" as it were - and then offering your stuff - especially when others have asked for it, rather than you "pimping" it.

Not to mention, it's damn good stuff and needs to be offered for sale. 
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on April 07, 2012, 11:39:19 am
The thing is, most everybody that knows Kristin and I know we live off-grid and they don't understand.  I get too many requests all the time from people who think they want a wind turbine too.  The first question I get is "how much money can I save on my bill" or "my bill keeps going up".  Well, your bill is REALLY going to go up after you spend $7-10 Grand on a wind turbine installation, with excavation work, concrete, wire and trenching it in, tower, turbine, and equipment.

So I have a policy that I will only build a machine for off-grid people.  Or for somebody who has a hybrid grid/off-grid system where the off-grid system powers part of their house with RE and battery backup.  These people understand what it's all about and realize there's better reasons to have an off-grid power system than "saving money on the bill".

You will NEVER save any money on your power costs by putting in an RE system to "save money on the bill".  Even with electricity double the cost of what it is now, you will never recover your costs in equipment.  The reason has to be the lifestyle and being independent, not the money.  There's only maybe 1% of the population that has the balls to tell the utility company to go fly a kite and live totally off-grid.  Those are the people I will build a turbine for.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: WindyOne on November 27, 2012, 10:23:13 pm
Chris,
 After reading 8 pages of this "blog", I have these questions ...

 Why did you decide to use ferrite magnets vs neo's?

 Would a 2.5 times more powerful neo magnet allow the elimination of the 1:2.5 transmission?

 Did having the transmission make anything easier or better?

 How much of an issue is corrosion with neo's?

 
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: Norm on November 27, 2012, 10:52:44 pm
I think since neos are getting more and more expensive that Chris
had decided to show that ferrite magnets thru overdrive transmissions
would make a machine to match one with neos and be more economical
in the long run......
....or so that was my understanding quite awhile back in one of his postings on
Otherpower.
Norm
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: WindyOne on November 27, 2012, 11:17:20 pm
What about neo's rusting ?
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: niall on November 27, 2012, 11:54:38 pm
?...

yes the neos  may rust ...(climate affected) .....the tail may get water logged and maybe mess with the furling....

the prop may get ingress of water at the the root studs and rot eventually ...balance etc....the yaw will get rusty and maybe twists in the cable ......

but all in all general maintenance will keep it going .......at least for a while ... :)
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: WindyOne on November 28, 2012, 09:14:46 am
yes the neos  may rust ...(climate affected)

I have seen pictures of neo magnets rusting and bursting through epoxy.
Once a neo magnet starts to rust, is it "terminal" like an unstoppable cancer?
If the rusted neo magnet must be removed and it was sealed in epoxy that could be significant work?

Ferrite advantages:
 1) Lower cost
 2) Superior corrosion resistance

Ferrite disadvantages:
 1) Lower magnetic strength
 2) Gear-Up transmission may be needed




Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: niall on November 28, 2012, 10:02:15 am
if it rusts from underneath its really bad news...the rotor will be rusting as well and holding moisture which speeds up the end .....if its just one mag you could maybe dig it out and replace with a spare

if it was a polyester cast rotor ( not really used anymore ) it could be a lost cause ...

if the mags rust on top ( stator rubbing , scratched coating or it just feels in rusty mood  :-\) the outlook is a little better , if you catch it early ( the next day ?) a clean and reseal with epoxy will slow down the rot .....but this also means taking down the mill more often to keep an eye on things .....

not everyone gets rusty neos though  :)......very much a climate problem or build quality issue  ( i think... )     
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on November 28, 2012, 02:44:21 pm
Why did you decide to use ferrite magnets vs neo's?

They're a lot cheaper.  Less than $1 for a big 2 x 2 x 1" thick magnet vs $8 for a 2 x 1 x .5" thick neo magnet.  The neo magnets were double that price when I built the first ferrite generator.  They have come down in price some now.

Quote
Would a 2.5 times more powerful neo magnet allow the elimination of the 1:2.5 transmission?

Yes.  Although I have also used the transmissions on neo magnet turbines as well.  Using the gearing allows you to develop the same power with a smaller and lighter (and cheaper) 12 pole generator instead of using a 16 pole on a 3.8 meter turbine, as an example.  So it still cuts the cost of the magnets because you don't have to use as many of them.

Quote
Did having the transmission make anything easier or better?

The electrical efficiency of the generator.  Since I started building geared turbines about three years ago now, I have not been able to build a direct drive one that can match the efficiency of the geared ones.  Especially with axials - the bigger you make an axial the bigger around it gets and the more copper it has in it.  The more copper you put in it, the higher the internal resistance.  You can even double the copper up (two-in-hand windings) and can't match the geared ones with a single winding in delta.

Hugh (Piggot) built a new design ferrite magnet direct drive turbine in the 3 meter class using my "pole cramming" method to keep diameter and weight smaller, after he saw that it works.  His turbine is pretty respectable from homebrew standards as compared to contemporary neo designs and it puts out about 750 watts.  But not even close to the 2.5 kW I get out of my geared ones.

Quote
How much of an issue is corrosion with neo's?

Pretty bad in some cases.  Ferrites can rust, but they never bubble up and form white balls of corrosion like neos do.  The only thing that protects neos from the weather is the coating on them.  Sealing them in resins doesn't work because moisture trapped in the resins during casting gets in, destroys the coating, and they bubble up and fall off.  Neo magnets are very, very fragile.
--
Chris
Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: WindyOne on November 30, 2012, 09:14:08 am
Chris,
 In your message dated "January 12, 2012, 04:30:25 PM" on page #1 of this thread there is a photo of your coils laying over the magnets. It appears that the "leg / side" of each coil is not parallel to the adjacent coil's leg. The outer shoulders of the coils touch but the inner shoulders have considerable space between them. This means the "legs" are not on the radius line (magnet center line) and are not 90 degrees square to the motion of the flux passing by. Do you know if this "angling in" of the legs causes any decrease in voltage produced or not? Less wire at the "V" means less I2R power loss in the coils - that is a good thing. How important is it that BOTH legs of the coils run down the exact Center-Line of the North and South poles when that coil is aligned with two of the magnets?

 Do you bond your coils with super-glue or just the tape them?

 Can any product be added to the coil windings, before being installed in the stator, to help them transfer the heat?

 What is "pole cramming"?

Title: Re: 3.2 meter ferrite magnet MPPT wind turbine
Post by: ChrisOlson on November 30, 2012, 11:59:52 am
They don't have to be "square" with the flux because if you look at the flux with a gauss meter it's a mess anyway and doesn't follow anything to do with the magnet shape or orientation.  It works by linking flux from one pole to another and the change is what induces the current.  Skewing poles or coil legs provides a sine wave with slightly less amplitude, but it's flatter so the voltage produced stays above the point where the rectifier stops conducting longer, which is better for battery charging.

I just tape the coils and put a lot of glass in the stator.  Glass transfers heat really well - plastic (resin) doesn't.

Pole cramming is fitting the most poles possible in a given diameter instead of using spacing that theoretically produces more flux in the air gap.  Hugh used to think that you have to space the magnets far enough apart to prevent "wasting" magnet surface area, and have a coil hole at least the size of the magnet.  Which is true to an extent, but that ends up with the result being spacing between coils and adding resistance to the stator.  The gains by reducing resistance and ignoring the very slight voltage drop by "wasting" magnet surface area with smaller coil holes and a wedge shape is greater than the "accepted" way of doing it in all the homebrew books.
--
Chris