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Wind energy => Wind energy generators => Topic started by: wantfreeenergy on September 19, 2008, 04:25:11 AM

Title: building your own alternator?
Post by: wantfreeenergy on September 19, 2008, 04:25:11 AM
Does anyone have a good site to learn about how to build a large alternator.  Somewhere in the 5kw size.

I have a pdf on building one that is somewhere around 200w, but would like to see how to build it larger.

Also is it better to use neo magnets for the alternator or will ceramic work?
Title: Re: building your own alternator?
Post by: z.monkey on September 19, 2008, 08:32:59 PM
Howdy Wantfreeenergy,

The Neodymium magnets have a higher energy density than the ceramic magnets.  However, alternators usually use an electromagnet for the rotor and not permanent magnets.  Permanent magnets that are subjected to heavy vibration can loose their polarization spontaneously.  Therefore an iron rotor with alternating splines and a central coil is used to provide the magnetization source to improve the reliability...

Blessed Be...
Title: Re: building your own alternator?
Post by: X00013 on September 19, 2008, 09:54:47 PM
My advice to you in order to save alot of headaches, is for u to go to the junk yard and buy 10 Japanese starter motors from the 1990's , chain ( link ) them together, 10 motors @ 12 volts will give u enuff volts and current for household stuff given you engineer it all correctly for given airspeed of your desired airfoil desighn, expect to pay 25 US or more for the starters. Good luck, google " starter motor wind generator"
Title: Re: building your own alternator?
Post by: X00013 on September 19, 2008, 09:57:48 PM
Fyi, I've done this myself and it was fun.
Title: Re: building your own alternator?
Post by: khabe on September 20, 2008, 12:16:44 AM
Permanent magnet generator is right choice. Neodymium magnets of course.  At first you have to know what is RPM you need. As lower RPM as larger diameter you need to choice. I have built very many PM 3 phase generators. 3 phase gen is the right choice!  5kW for windmill I built, was outer rotor style ca 14" ( 360mm) total diameter. I used 32 neodymium magnets  2" lenght, 1" wide and 3/4" hight, Stator had 36 pole, 188mm diameter and height 51mm - this stator was unknown manufactured just happy ebay find. I wound it concentrated style by scheme AaABbBCcCAaABbBCcCAaABbBCcCAaABbBCcC ,  used 36 parallel strands of 0.35mm enamelled copper (total ca 3,5mmq) 18 or was it even more turns per tooth. I did it by sections, like half and half stator , so each phase had two windings - was possible to connect parallel (7mmq, lower woltage/higher current) or series (3.5mmq , higher voltage/lower current) - and after that star or delta connection. It was somewhere after Millennium when I did build this monstrum. Was very hard to test it, I did it on one old lathe 780rpm,  20V when heavy loaded, current was 100A per each phase are the only notes I have made and I can see now. I did not try with rectifier - raises voltage ... and was no way to test it otherwise because giant sizes. This time I had no correct blades myself for examine it like windmill, I built ot for my friend who had no electricity in small island where he built his summer house - blades he received year or more later and he built it up himself included electronics - works well  up till today.
Some NZ and AU washing machines have similar stators I used, but somewhat twice thinners ... I used car wheel spindle as bearing system  - it must to be very rigid and strong!!!
This was 8 years ago,  it was iron core machine. You can choice air core (slotless) design,  or radial or axial ... + much more designs - op till today I have tried near all what possible.
Same range generator , 10kW, I built few months ago has ca 150mm of diameter, 50mm useful lenght (80mm total), specially ordered magnets, very special shape and expensive core material (only stator  costs EUR1k)  ... large amount of copper and small number of turns ... All materials must to be the best, and design must to be brilliant  - both costs a lot of  ::)
It feels like you have no how-know, no experiences - but anyway good luck to try.
The first one does not need to be so powerfull of course ... oh dear! 
You try to get at least 500W like first try - its fairly hard  ::)