Author Topic: Poles v Coils  (Read 8620 times)

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CWATTS

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Poles v Coils
« on: October 07, 2008, 12:44:36 PM »
What configuration should the magnets be for a 6coil, 3phase, 2pair stator be?
« Last Edit: October 07, 2008, 12:44:36 PM by (unknown) »

TomW

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Re: Poles v Coils
« Reply #1 on: October 07, 2008, 06:51:44 AM »
Axial Flux? Radial Flux? Conversion? Scratch Built?


You give less than enough information, my friend.


Maybe the mind readers can figure it out for you but a better bet would be full sentences expressing complete ideas.


Tom.

« Last Edit: October 07, 2008, 06:51:44 AM by TomW »

CWATTS

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Re: Poles v Coils
« Reply #2 on: October 07, 2008, 07:13:45 AM »
Hi

6 coils on a stator, each at 60 degrees. Where 2 opposite coils making a pair and each pair forming the 3 phase star/delta. For the magnetic poles being opposite to each coil when static, should they be placed around the rotor N - S - N - S - N - S.

I am confused that when a pole moves across a coil, should the other paired coil be receiving the very same pole face( ie both North or 1 North and 1 South )?
« Last Edit: October 07, 2008, 07:13:45 AM by CWATTS »

TomW

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Re: Poles v Coils
« Reply #3 on: October 07, 2008, 07:38:59 AM »
These pics show the coil / magnet relationship you want to try for:







"ElectricEd" posted these long ago and I archived them so not my graphics.


Hope it helps.


Also note that this was back when folks overlapped coils to pack in lots of copper. The basics are the same tho.


Tom

« Last Edit: October 07, 2008, 07:38:59 AM by TomW »

TomW

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Re: Poles v Coils
« Reply #4 on: October 07, 2008, 07:45:59 AM »
You might be better off ignoring the first graphic and concentrating on the second as it is more basic and less confusing than the lapped coils in #1. Pay particular attention to that N over one leg while S is over the other on each coil bit.


Tom

« Last Edit: October 07, 2008, 07:45:59 AM by TomW »

CWATTS

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Re: Poles v Coils
« Reply #5 on: October 07, 2008, 08:39:09 AM »




Thanks very much .... This is the answer I was after .. where each coil must see the same pole.
Please add my rubbed out version of your image to your archive.
It was really clear to see after black and blue phases were removed.
« Last Edit: October 07, 2008, 08:39:09 AM by CWATTS »

ghurd

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Re: Poles v Coils
« Reply #6 on: October 07, 2008, 01:35:42 PM »
I could be off track, but I think your answer is 8 magnets per disk.

G-
« Last Edit: October 07, 2008, 01:35:42 PM by ghurd »
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CWATTS

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Re: Poles v Coils
« Reply #7 on: October 07, 2008, 05:23:56 PM »
Hi
Thanks but it is actually 4 !!
I recalculated everything based upon all this above and decided to go less magnets rather than more coils.
But originally read somewhere 6 of each!!
Hence my question which was not based upon a known configuration.
But then I only know that now. Thanks to you guys.
So cheers for the help.
« Last Edit: October 07, 2008, 05:23:56 PM by CWATTS »

Flux

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Re: Poles v Coils
« Reply #8 on: October 08, 2008, 01:28:23 AM »
Starting from first principles you would end up with one coil per pole for a single phase winding. A 12 pole magnet system would have 12 coils per phase. As alternate coils are under alternate magnet polarities the connections to adjacent coils would need reversing ( or you flip alternate coils, same thing).


If you leave out alternate coils as you show that still works fine and no coils need reversing. You just alter the coil shape so that you use twice as many turns of twice csa wire for each coil and the end result is the same. That would give you a 6 coil 12 pole single phase winding.


Using conventional windings you will have to overlap coils to produce a 3 phase winding from either and that has been the standard way for many years. For axial flux machines where you need small air gaps and where the winding space is limited at the centre of the stator the overlapped coil is a challenge and it has been found that you get a better machine with far less effort if you go back to the original single phase concept and leave out half the coils of the basic half coil version ( leave out half of the coils of the 12 pole 6 coil version). That leaves you 3 coils per 12 poles and three phase will then go in as a single layer winding. It doesn't use all the stator circumference effectively ( there are unwound bits) but in real life there are so many compromises for wind power that when you consider all the issues this turns out a better winding. It wouldn't be the best way to wind a radial but the restrictions and compromises are different in that case.


Probably way off what you were looking for so ignore it if it adds confusion but this issue of pole numbers and coil numbers keeps cropping up and unless it is understood we shall be asked for evermore whether a certain pole and coil number will work.


Flux

« Last Edit: October 08, 2008, 01:28:23 AM by Flux »

CWATTS

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Re: Poles v Coils
« Reply #9 on: October 08, 2008, 03:55:08 AM »
Hi

Ok .. I made a paper stator and a paper rotor. Just to check pole rotation v coils.

Based on the above information where the Amplitude diagrams are clearly showing

what happens when Poles cross a coil.


If C = Nx(M/2)

where C = coils .. N = number of phases .. M = number of Magnets


6 = 3 x (4/2)


This is what I based my last statement on, and shows correct on my pretend stator/rotor model.

« Last Edit: October 08, 2008, 03:55:08 AM by CWATTS »

CWATTS

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Re: Poles v Coils
« Reply #10 on: October 08, 2008, 06:08:31 AM »
So now comes a question of spacing!! (PANCAKE STATOR AND ROTOR)

If 6 coils are equally spaced at 60 degrees and 4 magnets are at 90 degrees, Obviously the magnets will always be positioned directly above the coils.

But should the coils be spaced closely together?
« Last Edit: October 08, 2008, 06:08:31 AM by CWATTS »

Flux

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Re: Poles v Coils
« Reply #11 on: October 08, 2008, 06:13:09 AM »
If you are doing a single layer axial 3 phase with 6 coils then the answer is you need 8 magnets ( the old 4/3 ratio).


Just ignore all that I said in that last post, it is just confusing you.


You have come up with a formula to solve a problem that I never even thought of before, I am not mathematically inclined. I just remember 4 magnets to 3 coils.


Flux

« Last Edit: October 08, 2008, 06:13:09 AM by Flux »

ghurd

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Re: Poles v Coils
« Reply #12 on: October 08, 2008, 06:38:40 AM »
Do the coils overlap?

There is a 3:4 or 4:3 ratio worth a google.  3 coils and 4 magnets (per disk).

So 6 coils is 8 magnets, 9 coils is 12 magnets, 12 coils is 16 magnets...


The coils should be close to each other.

G-

« Last Edit: October 08, 2008, 06:38:40 AM by ghurd »
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CWATTS

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Re: Poles v Coils
« Reply #13 on: October 08, 2008, 06:47:20 AM »
Hi

Thanks for this .. So 8 at 45 degrees is better than 4 at 90.

Would I be correct in saying this = a smoother output or would it be a higher voltage?
« Last Edit: October 08, 2008, 06:47:20 AM by CWATTS »

ghurd

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Re: Poles v Coils
« Reply #14 on: October 08, 2008, 06:57:37 AM »
Smoother output, smoother operation, higher voltage, and more output.

G-
« Last Edit: October 08, 2008, 06:57:37 AM by ghurd »
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CWATTS

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Re: Poles v Coils
« Reply #15 on: October 08, 2008, 07:10:35 AM »
Thanks .. I shall vist the Dump again for another microwave oven . . hehe
« Last Edit: October 08, 2008, 07:10:35 AM by CWATTS »

classradiance

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Re: Poles v Coils
« Reply #16 on: September 20, 2012, 03:55:49 PM »
 :)

classradiance

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Re: Poles v Coils
« Reply #17 on: October 01, 2012, 03:29:39 PM »
Smoother output, smoother operation, higher voltage, and more output.

G-

Hey ghurd
seems you were helping me the last time   ..... :)  I forgot my cwatts password and created another account called classradiance.

no wind now, Just Solar

finnsawyer

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Re: Poles v Coils
« Reply #18 on: October 24, 2012, 10:31:43 PM »
       I feel that some misconceptions have crept into this thread.  The excellent diagrams that TomW has provided deserve some study.  Note that the colis of each phase are seperated by one magnet diameter.  Given that requirement, then the conclusion that a three phase alternator with magnets on one rotor can be built with four magnets and six coils is correct.  That is, two coils per phase.  In fact, any even number of magnets can be used with the number of coils per phase equal to half the number of magnets.  For instance, a ten magnet alternator would require five coils per phase, or fifteen coils in all.  We could call this design the 2 magnet 3 coil three phase alternator.  This design might be very attractive to the person who has six or ten magnets in hand.  Why throw away two expensive magnets to get to the 4 magnet 3 coil scrunched up design?
     The 18 magnet 9 coil per phase design is of special interest to me.  If one removes 12 magnets in pairs leaving the remaining six to alternate poles, one gets the alternator desingn that I proposed some time back.  In general, if the number of magnets is devisible by 3, then two thirds of the magnets can always be removed to yield a new alternator.  Six magnets three coils then yields two magnets three coils, my original desingn.  There are a lot of posibillities.  Do what works best for you. ;D

classradiance

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Re: Poles v Coils
« Reply #19 on: November 04, 2012, 04:11:16 AM »
       I feel that some misconceptions have crept into this thread.  There are a lot of posibillities.  Do what works best for you. ;D

Is there any Simulation software out there for  Stator/Rotary design !! Obviously being able to model would be very helpful .

classradiance

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Re: Poles v Coils
« Reply #20 on: December 07, 2012, 12:29:37 PM »
 :)

electrondady1

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Re: Poles v Coils
« Reply #21 on: December 07, 2012, 12:36:55 PM »
the hi teck method i use is a good drawing of a mag rotor layout
and a piece of tracing paper with a drawing of the coil configuration.
with a thumb tack at center you now can rotated the drawings and see how every thing connects