Page 1 of 1

Magnets & coils

PostPosted: Sun Jul 04, 2010 4:52 pm
by dimitrisyn
Hello everybody,
Guys I' been searching about windgenerators about a year and found this forum just now!
I really admire your job and hope that sometime I will build my own. I' ve searched enough the forum but couldn't find answer into two questions:
1. Three sets of coils for three phases; why 12 magnets and not 3 aligned with one set of coils so in one turn all sets will produce electricity. I think the difference between phases will still be at 120 degrees so the efficiency will stil be the same (if I'm right).
2. I think I've read in the forum that coils worm up; if I don't want to use plywood what else can I use to make the stator? Can it be aluminium for instance?


Re: Magnets & coils

PostPosted: Mon Jul 05, 2010 1:22 pm
by windgat

1. The idea of 12 magnets vs 9 coils is to keep the three phases apart. So as one set of coils is getting maximum power, the other two are in between maximums. That way there is always one phase at maximum power.

2. Nothing that conducts electricity (other wise energy is wasted in eddy current). Resin is the best that I know of. Ideally it must be
- non conducting
- non brittle - a good conductor of hea
- heat resistant (musnt burn)

Re: Magnets & coils

PostPosted: Mon Jul 05, 2010 2:35 pm
by dimitrisyn
You 're right! I got it. One at max power, one starting and one ending. May I ask something else? You said about magnets alternating. You mean pairs should be S-N N-S...S-N or one plate all magnets South and the other plate all North? I belive you mean the second.

Re: Magnets & coils

PostPosted: Tue Jul 06, 2010 1:35 am
by dimitrisyn
Hey Windgat,
Is there a complete guide of what should be taken in mind when trying to calculate the whole constraction? I mean what should I start from? The wind in my area, the voltage, the watts I want? Sorry man, I'm a bit confused.

P.S. If possible, please make a list with the terminology we use here and the effection on windgenerator. :roll:

Re: Magnets & coils

PostPosted: Sun Jul 11, 2010 8:29 pm
by windgat
The magnets must alternate on one plate. N up, S up, N up etc. That's why there must be an even number of magnets.

Then the two rotors must be aligned so that they attract. And boy, will they attract! Enough to literally crush your hand, so be careful!

A complete guide... I wish! I am trying to work something out as I go, but its complicated. Start with max theoretical power
P = 0.35 A v^3
Where A is swept area of blades, v speed in m/s, and P power in watts.

Then you need to work with tip speed ratio, and the RPM vs watt graph of your generator (a straight line).

If you figure out a complete guide, let us know!