± 500w @ 150rpm Alternator for my VAWT

[Yves777]

Hi to all,
I am new on Otherpower and I really please of all what I found about windmill. Bravo to all.
Since a few years, I have made several models of windmill. I really prefer VAWT.

http://www.youtube.com/watch?v=GumsKjwckJM

After viewing the video, I know that you think that my windmill is not at a proper place, I admit, but since I could make it work at that place, between trees, imagine it at 60' in the air.
I think I have come up with a fairly usable model but after having built several alternator, I should say that I am on the wrong track. My last version is the worst that I have ever done. Well, now I know how not to do it.
I have always send my power to a 12v bank of battery but as I could read here, I should go for an higher voltage too.
I have play a lot with the PMA.xls Excel utility and I did not come up yet with a good setup.

I am looking for an alternator that can give ± 200w @ 150-200rpm.
Or is it better to look for ± 400w @ 150-200rpm, or ± 50w @ 50rpm.
That is a hubby only, I am not going of grid.

From your experience, where should I start or look for as an example on this forum ?

Thanks

Yves

[Flux]

You can't base things on one speed. You need the cut in speed of your turbine in say 7mph wind and you need the power of the turbine in a wind of perhaps 20 to 30 mph.

You can satisfy the cut in requirement with any alternator but if the magnet system is too small it will not handle the power in higher winds.

150 rpm is just about cut in speed for most reasonable size HAWts.

Without more details I would look on Otherpower for an alternator for a 10ft turbine and consider winding with at least 3 times the number of turns to get down to 50 rpm cut in. Even so I suspect it will be hard pushed to deliver 150W continuously with the thin wire.

The alternator that works best will be the one that best matches your turbine and you probably wont' get there without knowing something of your turbines power curve .Low speed alternators become big heavy and expensive. For a VAWT with good torque you may find you can do better with a chain speed increasing drive rather than a very slow alternator.

Flux

[electrondady1]

hello
i checked out your videos.
it appears you are using aluminum  rotors
the mag rotors  should be made of mild steal.
the magnets must sit on top of those steel disks.
this should double your out put.

[Yves777]

ElectronDady1
hello
i checked out your videos.
it appears you are using aluminum  rotors
the mag rotors  should be made of mild steal.
the magnets must sit on top of those steel disks.
this should double your out put.

Yes now I know. But I have done worst like inserting the magnet in the aluminium. That cause a LOT of Eddy current and make the alternator very hard to spin over 50rpm.
That is why am I asking some advices here to  finally make a not so bad alternator.

Yves

[Yves777]

Hi Flux,

well the current alternator that is turning on my VAWT is via a chain, 4/1.
I have put it there to test the possibility of a gearing or chain or very flat belt.
It is working surprising well for ease of start to spin.
This alternator is not what I need because it is rated to 1500rpm and I am looking for 500rpm alternator.

You talk about knowing the power curve of a wind turbine to match the alternator.
Is there a topic here that I could read to understand how I could do that ?

Yves

[electrondady1]

swept area is everything
here is a link to a calculator

http://usvawt.com/cgi/windpower.cgi

it will give you some idea as to how much power can be harvested from your gyro mill.

[Flux]

I am not an expert on VAWTs but that link from Electrondady should give you quite a good guide.

Regarding the alternator itself, again Electrondady is right in that you need steel rotor discs.

Take a good look at the construction of the alternators on the Otherpower site, you will do best to stick to that design with dual rotor. For decent results it is essential to have the magnetic circuit as closed as possible. Using non magnetic discs will drastically reduce the output.

Flux