Project Journals > Chris Olson
3.2 meter ferrite magnet MPPT wind turbine
ChrisOlson:
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).
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Chris
Wolvenar:
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/
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.
ChrisOlson:
--- Quote from: Wolvenar on January 12, 2012, 01:43:28 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.
--- End quote ---
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.
--- End quote ---
Ok, photos of bikini-clad wife go in Global Warming album ;D
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Chris
ChrisOlson:
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:
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:
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)
//www.youtube.com/watch?v=8kLAFPaX88U
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Chris
Wolvenar:
Looks like some nice work there Chris
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