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Electrical and Magnetic Circuits of a Motor

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Patrick

Tue Jan 28 2014, 02:00AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

im trying to figure out whether i should use delta or wye connections, but at least ive found my spool of good wire, and have the dead stator striped...

im going to use delta, and it seems I can get 3 strands of 0.015" wire in each pocket. im debating whether to add a tiny thermistor, like that cheap radioshack one, at a hot spot.

EDIT: being tipsy and or drunk isn't helping..m... mds.\\\\fsd

EDIT2: 8 turns with 3 strands of 28 awg is doable, in fact its looking real good.

EDIT3: ive been able to get 8 turns on two close teeth, im wondering if using thermal epoxy is a good idea? I could fill the whole thing with epoxy as I wind each tooth, I certain wont have more air voids than I do now...

EDIT4: I see what some of you are saying. the currnet will drop, but the voltage needed for a constant RPM will rise. (I think, the epiphany comes and goes, its all a bit blurry ATM)

Shrad

Tue Jan 28 2014, 08:44AM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

for info on the actuators I mentioned :

I think the two opposed windings will behave like each of the windings you have in such a brushless motor, and the ideas used to improve the field strength and thermal design may apply to your application

Ash Small

Tue Jan 28 2014, 12:07PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Using epoxy may make it more difficult to re-wind them again.

Patrick

Tue Jan 28 2014, 02:41PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Ash Small wrote ...

Using epoxy may make it more difficult to re-wind them again.

im thinking impossible.

im wanting to use the arctic silver 2-part epoxy, which is meant for heat conduciton, but is still electrically resistive.

Carbon_Rod

Thu Jan 30 2014, 09:57AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

@Patric,
try cryogenic cooling with a liquid spray from a small can of compressed air propellant.

High KV motors are often used with a reduction gear assembly to handle larger props.

Google cache of blocked URL:

Patrick

Thu Jan 30 2014, 01:23PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Carbon_Rod wrote ...

@Patric,
try cryogenic cooling with a liquid spray from a small can of compressed air propellant.

High KV motors are often used with a reduction gear assembly to handle larger props.

i dont see the advantage of carrying a can of gas, vs just going another size up in motor.
and yes the AR Drones use reduction bull gears, and a really high speed tiny motor. I guess theve calculated all this out and now how to get an optimum flight on a tiny battery.

Patrick

Sun Feb 02 2014, 05:54AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

If power = torque x RPM, going to 8 turns may not matter. And if heat losses are inversely square to copper area. maybe i should just wind better wire in larger circular mils at 7 turns?

though 8 turns would increase coupling, i think...im not sure this'id matter though. Im still wading through the physics.

Dr. Slack

Sun Feb 02 2014, 11:01AM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

Heat losses depend on copper *MASS*, not copper area (other things being optimally designed for a motor of given power). This is one of the cases where you get what you pay for, directly in terms of materials. Buy less copper, and your power goes down, or your losses up. Buy a stronger magnet, everything else gets better.

Patrick

Mon Feb 03 2014, 12:57AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Dr. Slack wrote ...

Heat losses depend on copper *MASS*, not copper area (other things being optimally designed for a motor of given power). This is one of the cases where you get what you pay for, directly in terms of materials. Buy less copper, and your power goes down, or your losses up. Buy a stronger magnet, everything else gets better.

if the length is constant, increasing diameter does increase mass.

Patrick

Tue Feb 04 2014, 05:20AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

im looking at this pic, called a "DLRK" wind. im thinking this is preferred in the air hobbies for its low resistance high current capability?

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