Almost Ready...

[Hoskald]

Starting the process for making my first wind genny, just for fun and education mostly.

The Specs:

Dual rotors, 11" dia 1/4" thick, 16 rare earth mags (1x2x1/2"), 12 coils 16AWG 80 turns(?), 3 phase, 24v. Now my question is will this overpower a 5' dia blade set, tsr 8,?  With this blade set I estimate cut-in at 300 rpm. Or would it be better to reduce the size (number of mags, etc)? The initial goal is 300 watts peak power out, but I would like to be able to use it other projects but I understand that it might not be feasible.

Thoughts?

Cheers,

Hos

[Flux]

Where do you want to start?

If you have settled on 5ft blades with a cut in of 300rpm then you miss by a mile. I wouldn't recommend squeezing 16 of those magnets on to a disc 11" diameter. Assuming you manage it and get your 80 turns then your cut in speed for the alternator will be nearer 75 rpm. It should be powerful enough for a 10ft prop.

The low cut in will kill your prop, you could at least throw one magnet rotor away and still have cut in below 300 with a fair gap between rotor and stator. You would need series resistance in the line even then to hold it out of stall.

If you have settled on the prop size then 8 magnets on each disc, dual rotor will do considerably more than you want. I think I would try it with 8 magnets on one disc and none on the other, that should manage 5ft quite nicely. You would be looking at near 100 turns and on those discs you might squeeze your #16 wire in with care. Stator about 1/2" thick.

Make yourself a 5ft test machine and save the remaining 24 magnets to make an 8ft one later.

Flux

[Hoskald]

Thanks for the input...though I'm confused about where the other 24 mags come from...I see part of the problem is that I was not clear that it was 8 mags per rotor, sorry about that.

I am thinking at this point it is best to go single rotor and add the second rotor at a later date when I increase the blade set dia to 10'.

Another thing that I didn't mention is that the stator would be 5/8". Is it better to with the smaller wire and bring the stator down to 1/2"?

Thanks again!

[Flux]

You mean 8 magnets per rotor? 16 magnets total. If so you will need to do a strange winding to use 12 coils. The normal arrangement with 8 poles would be 6 coils to do it as a single layer winding.

You will not do it with a conventional single rotor with 8 magnets on one disc. ( you could have done it with 16)

You have to choose between 8 pole dual rotor and 8 pole single rotor with a spinning disc with no magnets ( still basically dual rotor).

If you go for dual rotor with magnets on both then 5/8 thick stator will be fine. If you go for the other option you will do better with a shorter gap ( stator 1/2" thick).

Flux

[Hoskald]

Thanks for clearing up the pole/mag issue for me.  It was unclear in my earlier reading how that worked.

I think I will proceed with the dual rotor (16 total mags) and increase the blade length to around 8' or so and bring the tsr down to somewhere around 6 (I haven't worked the calculations yet so bear with me).

I know that it seems that I am re-inventing the wheel, but if I follow a plan, I fail to learn the basics upon which the plan is based. So when I really want to learn something I have to go back to first principles and work it out. Thank you for your very patient guidance!

Cheers!,