Six coils or Nine Coils

[d1kta]

Hello i am making first time wind turbine alternator
i have 12 magnets 40x25x10 neodymium
i made 6 coils but i wanna more 3 coils in this picture



what must i do, 6 magnets front, 6 magnets behind and 6 coils or
6 magnets front 6 magnets behinde and 9 coils

which is the best ?

these are my coils

[tecker]

12 and 12 with your satator

[kitestrings]

d1kta,

It's not clear to me what you are doing.  The drawing is a sketch I made of a 16-pole alternator.  Typically with a dual-rotor alternator (two magnet rotors and the coils sandwiched in the middle) there is a 4:3 ratio of poles to coils.  Other combinations are possible, but this is one of the more common.  The sketch has 4 coils in series; 12 total, then there are two magnet rotors, each with 16 magnets.

You said you have 12 magnets.  You could do 9 coils, and do a single magnet rotor (with just a steel rotor on the opposite side), or get 12 more magnets.  You could also do 6 coils with 8 magnets on each rotor, but you'd need 4 more.  With nine coils, you'd have 3 in series; with 8 there would be 2 coils in series.

If you provide the rotor (blades) diameter and details of what you're aiming for, you probably will get a better response and fit for your application.

Good luck, ~ks

[d1kta]

d1kta,

It's not clear to me what you are doing.  The drawing is a sketch I made of a 16-pole alternator.  Typically with a dual-rotor alternator (two magnet rotors and the coils sandwiched in the middle) there is a 4:3 ratio of poles to coils.  Other combinations are possible, but this is one of the more common.  The sketch has 4 coils in series; 12 total, then there are two magnet rotors, each with 16 magnets.

You said you have 12 magnets.  You could do 9 coils, and do a single magnet rotor (with just a steel rotor on the opposite side), or get 12 more magnets.  You could also do 6 coils with 8 magnets on each rotor, but you'd need 4 more.  With nine coils, you'd have 3 in series; with 8 there would be 2 coils in series.

If you provide the rotor (blades) diameter and details of what you're aiming for, you probably will get a better response and fit for your application.

Good luck, ~ks

Ks thank you very much, you understand very well, i wanna ask something, is there any article or formula about 4:3 ratio, and if i use 6 magnets on each side and 6 coils,  my alternator doesn't work ?

[electrondady1]

you can do 6 mags on each rotor and 6 coils total for a single phase dual rotor.

[kitestrings]

is there any article or formula about 4:3 ratio, and if i use 6 magnets on each side and 6 coils,  my alternator doesn't work ?

There's been quite a bit of discussion on this on this board.  This might be of interest.

http://www.fieldlines.com/index.php/topic,146723.msg1006919.html

I'm not the expert on this topic.  Hopefully others may follow with better explanation.  My understanding is that single-phase alternators, at lower rpm, run quite a bit rougher than 3-phase due to torque pulsation presumably from going from the peak of the wave-form thru the zero crossing with each cycle.  And that, comparatively 3-phase is smoother, and more efficiently uses the available winding space.

Hope this helps.  ~ks

[Flux]

"is there any article or formula about 4:3 ratio, and if i use 6 magnets on each side and 6 coils,  my alternator doesn't work ?"

Your 6 coils will work with 6 magnets each side, it is a single phase winding and you need to reverse alternate coils.

For a small machine single phase may be ok, but for larger machines the vibration can be very destructive and most choose to use 3 phase. The 4;3 magnet /coil ratio winding is a very simplified 3 phase winding devised by Hugh Piggott and lends itself to an easy and effective winding for axial machines where overlapped coils are difficult.

You may do well to look at Hugh's site www.scoraigwind.com , he has a lot of useful information there but I don't think he explains how the winding was derived.

If you consider a 12 coil single phase case, you would make it 3 phase by adding two more identical windings 120 electrical degrees apart. you would have 36 coils and they have to overlap. If you leave out some of the coils in each phase they can be arranged as a single layer. You reach this point with 9 coils, 3 of which are in each phase. For a radial machine overlapped coils may get you a better result as you use all the winding area, but for axials the crossing of coils at the inner radius is a big challenge and unless you are a very experienced winder with time to spare you will do better with the simple single layer arrangement.

Flux