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MacGyver

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Joined: 12/05/2009
Location: United States
Posts: 1329

Posted: 04:49am 13 Oct 2010

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Crew

I can't build anything for another few months (complicated) so I've been monkeying around with my compass and making lots of drawings. I have a general question to throw out:

Is there any reason "skein" windings are not used on an axial-flux design? I did a mock-up of both a traditional coil-wound stator and one of a skein-wound stator and found (on paper at least) that the skein winging used 1/4 less copper wire. Seems to me that using a lesser amount of wire while maintaining the same number of wire runs across the flux pathway would mean a larger-size wire could be used.

I should tell you that my stator (drawing) is single-phase. I build little stuff and am after only 12 to 15 volts (max 500 watts) so if I were to build it 3-phase, I'd have to have 3 stators. I suppose that's one reason to use the traditional coils, but aside from that, is there any other reason skein windings aren't used more?

When I am again able to build again (March 2011) I intend building a skein-wound stator for my little 4" Ax-Fx toy just to see how well (if ???) it works. By the way, the "off-the-shelf" DIY ax-fx build is almost a done deal. As soon as I have some heli-arc welding done, I'll toss up some pics.

Comments?

Edit: Changed 1/3 to 1/4 (chubby fingers)

. . . . . Mac Edited by MacGyver 2010-10-14

Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas

Tinker

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Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 10:11am 13 Oct 2010

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Hi Mac,

Its a long time since I did motor rewinding at tech college. I do remember that skein winding was used for starter windings on single phase motors, never for the run winding.
I guess it has something to do with starter windings being lots of turns of thin wire and run windings fewer turns of thicker wire.
Maybe the 'skeining' does not work well with thick wire.
Why don't you try it out and let us know?

Klaus

windlight
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Joined: 03/03/2007
Location: Australia
Posts: 331

Posted: 10:34am 13 Oct 2010

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To my logic you can set out your magnets however you wish, what you may change is the waveform, essentially if it takes longer for the magnet to pass the coil leg then the waveform will be flatter & longer. Without a pic of your idea all a bit hard to say but as Tinker said give it a go.

allan

"I like this place and willingly could waste my time in it" - (Act II, Scene IV).

MacGyver

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Joined: 12/05/2009
Location: United States
Posts: 1329

Posted: 04:13pm 13 Oct 2010

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Thanks for the input. I was merely trying to do a little "research" before tackling it on my own, which I will do just as soon as all my machinery is out of storage (March 2011). I'm in the process of 'untying the knot' and didn't want to come home to hammer marks all over my stuff!

I'll make a couple up and try them in my mini ax-fx as well as my radial-flux machines and post pics and all, but it'll have to wait.

Thanks again.

. . . . . Mac

Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas

Orphanjt

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Joined: 04/08/2010
Location: Kenya
Posts: 2

Posted: 03:45am 20 Oct 2010

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Hello MacGyver,

Not sure if I have got exactly what you're attempting. But I can offer some experience - we attempted to rebuild and run a small tiger generator as a windmill, thinking that we could take advantage of the size of the stator for the relatively low cost. But Tiger generators, being cheap, are wound in 1 phase. This is fine when you run them as a generator - the higher RPMs flatten out the sin curves to an acceptable level, but when you run them at direct drive windmill RPMs the fluctuation makes the power output useless.

(Note that a single phase power curve, even with a higher frequency will eventually burn yr battery out faster than a 3 phase triple sin wave)

MacGyver

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Joined: 12/05/2009
Location: United States
Posts: 1329

Posted: 04:53pm 20 Oct 2010

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Orphanjt

I think I would agree with this. I've been talking to a colleague who lives on Flinders Island, Tasmania who doesn't post here any longer, but is well known and respected by the crew here and he too said what you said.

To that end, I've increased the size (thickness) of my magnets to allow for a 5/8" air gap on my tiny ax-fx design and will run three skein-wound stators, each 120* apart and pull the wiring off in "star". There should be room enough as each full wind is comprised of 15 turns around the posts. That times 12 locations and connected in star produces just a tad over 15 volts per coil.

I may adjust the number of turns in each winding for the final put-together; I'll have to run a test coil to find out. My numbers here are based on personal experience using the same mechanical piece of gear with individual coils laid up in a "traditional" stator. One coil of 160 turns produced 2.2 volts a.c. and that works out to around 15 volts when all the math is done.

The reason I'm switching to a skein-wound stator is it's easier to lay up the stator than using individually-wound tiny coils and it leaves more room for me to overlap three winds for 3-phase output. It also uses 1/4th less copper wire than coils do. I'm hoping to be able to wind this with 14-gauge copper wire; we'll see.

Thanks for your input.

. . . . . Mac

Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas

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