3.2 meter ferrite magnet MPPT wind turbine

[ChrisOlson]

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.
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Chris

[bvan1941]

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 !

[ChrisOlson]

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

[DLoefffler]

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

[ChrisOlson]

Hi Dennis,

• The transmission case is a weldment, made of 1/4" sheet steel.
• The mainshaft is forged, hardened (Rockwell 45) and tempered 30 mm 4140 chromoly steel
• The PTO shaft is 1" cold rolled mild steel
• The main bearings are SKF (Sweden) extended race, dual row, angular contact ball rated for both full axial and radial load
• The PTO bearings are SKF (USA) single row radial ball rated for 1/3 axial load of the max radial load
• The drive sprocket is 30 tooth
• The driven sprocket is 12 tooth, hardened and tempered 4140 chromoly steel
• The drive chain is #40 stainless steel with brass bushed rollers

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.
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Chris

[DLoefffler]

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

[Jarrod9155]

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

[ChrisOlson]

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

[ChrisOlson]

    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

[Dave B.]

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.

 

[ChrisOlson]

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!!!"
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Chris

[rossw]

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.

[ChrisOlson]

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.   
--
Chris

[Jarrod9155]

  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

[philb]

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.