Alternator for Turbine

Towards the bottom of this link, there is a complete tutorial on how to build a home wind turbine, including construction of a direct drive 3-phase alternator.

http://www.otherpower.com/turbineplans.shtml

This site has realistic info on home energy projects. Watch out for the sales hype and junk science that many other sites promote.

Why 3 phase? If you are thinking of feeding the grid for money back, then you have a very expensive way to go indeed, or even to supply your own needs in 3 phase.....

Firstly you need to have a wind turbine that has good speed keeping qualities to supply only 50 or 60 Hz as the case may be....This alone would give me nightmares of control electronics and mechanics.

Also your windmill is TINY!! How much power will you be able to draw even in a storm, let it be 1KW, but how often do you have such storms???? Normally something like that would be lucky to supply 150watts on a good windy day.

Remember that generally speaking windmills (in Europe at least) work for about 28% of the year, no more, no less........payback is slow......

In your case I would go for 12 volts with a modified car alternator with a PMA fitted, and rectify the output and charge up leisure batteries......big ones to get over windless times.......use an inverter for mains voltage at single phase when required, make sure its at least 90% efficient - or better!

With the right inverter system, its also possible to feedback power into the grid, via an approved switching system - but again costly.

Sorry to be so negative......maybe someone else can help in a more positive manner....

We all know using an alternator is best because we don't have to worry about the commutator. If you wind your own alternator such as the ones designed by Hugh Piggot, then you can make a switching device to change from Wye to Delta connection. Use the wye connection for low wind conditions and the delta connection for higher winds. Use 3 bridge rectifiers to change from AC to DC for charging the batteries. It is a good idea to have a charge controller so as to not overcharge the batteries which damages them. Plans to build a charge controller can build can be found at ifred2006@yahoo.com

I found several entries on Ebay for purpose built PM alternators on ebay.

http://shop.ebay.com/i.html?_nkw=permanent+magnet+alternator&_sacat=0&_trksid=p3286.m270.l1311&_odkw=PM+alternator&_osacat=0

with a High current (say 145A or thereabouts) field coil alternator (Delco Remy 21SI or equivalent modified for self-exciting operation, I would not use a PM one, regulating the output becomes difficult.) you can expect to get about 1700W max out of it and that is at 6,000 rpm. Not a huge amount of current. Don't expect to run your whole house with it.

Good post.

But whoever heard of a direct drive (wishes of OP) windmill achieving 6000RPM? It would need gearing up to achieve that I feel, eg.not direct drive as wished.....

Most will start generating power at around 1000 rpm and peak at between 6000 and 8000 rpm. A straightforward single stage gear drive should be able to step the rpm of the windmill up to a usable speed which was what I assumed would be needed.

You are dead right, the OP wanted it on the same shaft though, a wish that would be difficult to fulfill I feel......

eh maybe not...

http://www.toledogear.com/inline-parallel-shaft-gear-reducers.html

http://bostongear.com/pdf/product_sections/200_series_helical.pdf

What he wrote was:-

I want to make a direct drive alternator/generator for a wind turbine with a 1.5m diameter.

Maybe your find will excite him for a few better ideas!!! Good post!

your very small 1.5 meter will not be worth the time and money,Put your money into a solar panel.Ive made a few vawt and my own alternator 3 pahse and then you change that to 12 vdc with 3 ,3 phase rectifiers.Not hard,all answers are on the net.Last one I made was 3 meters tall and 1 meter wide,3 blades. NEXT you have to have alot of wind ,above 7/10 miles per hour,or don't even start.

Go and buy solar panels.alot better.and they work with no wind.ha ha ha

Or use the solar panels as the blades for your wind turbine.hahahaha

Good luck.