metal in stator
By Mentally Moribund, Section Wind Posted on Thu Nov 25, 2004 at 07:04:56 PM MST
has anyone expiermented with this before

I just got my coils wound for my wind gen.  I know I've read issues with eddy currents when putting metal blocks inside coils.   My thoughts are just a thin 12ga strip of metal sitting on the inside side walls of the coils and maybe one in between the coils.  Would this feed a little more magnet juice to my coils?

metal in stator | 8 comments (8 topical)

Re: metal in stator (3.00 / 0) (#1) by picmacmillan on Thu Nov 25, 2004 at 07:22:44 PM MST

internetfred has done some extensive testing using metals in his coils etc...give him a shout and i'm sure he could answer some of your questions about eddie currents etc.. http://www.frecklefarmloghomes.com

Re: metal in stator (3.00 / 0) (#2) by p0lizei on Thu Nov 25, 2004 at 08:07:32 PM MST

With my newfound knowledge in eddy currents, I am now more than qualified to Know Just Enough to be Dangerous :0p  I will offer a potential problem that came to mind when you mentioned this (I'd thought of doing the same thing a while back).  Eddy currents are going to resist the magnet's passage over the coils, and this is caused by the coils acting as electromagnets when current is running through them.  If you have a piece of metal in your coils (I assume you're talking about steel or some other magnetic metal), won't that tend to resist the motion of the rotor as well?   I'm not saying that this is how it WOULD happen, but that was the problem that I thought of when I was considering doing the same thing. *anxiously awaits iFred's well thought out, detailed analysis of the problem) :0)

Re: metal in stator (3.00 / 0) (#3) by test lab guy on Fri Nov 26, 2004 at 09:17:23 AM MST

Please describe more of your project.  Are you working with an axial or radial configuration?  You have coils with no iron and are now wanting to add the iron in to the mix? There maybe some iron we can borrow from motors or transformers that will work better than thick carbon steel plates.

Re: metal in stator (3.00 / 0) (#4) by Mentally Moribund on Fri Nov 26, 2004 at 10:51:21 AM MST

This is what I'm talking about doing.

Re: metal in stator (3.00 / 0) (#5) by test lab guy on Fri Nov 26, 2004 at 12:16:03 PM MST

This looks like an axial design.  Yes?  How many coils do you have and how many magnets do you have?  I believe the iron would have to be "U" shaped, the two ends of the "U" poking through the center opening of two adjacent coils, but daisy-chained "U"s going all the way around and linking all coils.  I don't know how clear that is.  The reason I asked about the number of coils and magnets is you may experience some significant cogging if the number of coils equal the number  of magnets or equal 3x the number of magnets. [ Parent ]

Re: metal in stator (3.00 / 0) (#6) by Mentally Moribund on Sat Nov 27, 2004 at 09:28:24 AM MST

I'm running 16 magnets and 12 coils (three phase),  I think I will just expiement with this idea while my gen is still on the ground.  I will post my findings.

Re: metal in stator (3.00 / 0) (#7) by test lab guy on Sat Nov 27, 2004 at 02:24:33 PM MST

That sounds like it should work just fine.  If adding more and more iron causes too much cogging, then you should be able to find a happy median.  On the prototype I built, I was able to get a feel for the iron or eddy current losses by running the thing without an electrical load on the windings and measuring the input torque.  I tried a couple of different iron cores (prototype made from an old Chrysler alternator) and I could definately tell the difference between a good and a bad core.  You don't even need windings, just run the thing (with rotor modified with magnets) and a bad core will heat up faster and require more running torque.  Any cogging torque you may have will have to mechanically filtered to get a stable force reading on the moment arm.  The net steady state torque due to cogging should be zero as all the push/pulls cancel each other out.  Have fun, sounds like a great project!! Regards, TLG [ Parent ]

Re: metal in stator (3.00 / 0) (#8) by Mentally Moribund on Sat Nov 27, 2004 at 10:25:27 PM MST

thanks test lab guy, that's just the tid bit of info I needed.

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