I bought a few 30 watt 3 phase motor/generators in supposedly delta configuration from a ali express. the motor did have only 3 wires coming out, plus the manual stating it, I am pretty sure this was supposed to be a delta set up. I opened one up and interestingly there were 10 poles for the magnet, which is already out of phase with what I have known so far to be the optimal range for 3 phase motors to work in, where the magnets hit all the coils of one phase at the same time. But more troubling was when i did a connectivity test between coils, and all interact with each other. with the 3 output wires not touching of course.

Now oddly enough they still manage to generate some electricity which made me wonder, is this some sort of set up that is usually used in the industry? or are they just made wrong? I have yet to take it apart to see if the coils are coiled all in the same direction, or which ones are in which direction, but any insight would be appreciated.

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    \$\begingroup\$ Is there any reason not to include a photo in your post? Our usual advice is, "No datasheet? No sale!" \$\endgroup\$ – Transistor Sep 27 '18 at 21:08
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    \$\begingroup\$ Delta allows the Common Mode to be floating. How did you test your perceived "interaction"? Meanwhile, all coils being all connected, this is normal if high impedance testing. Yet you did not specify your test method or impedance or Zpu during this test. I might suggest a D-Y transformer with neutral to a balanced load. The number of poles is irrelevant except for kV/RPM unless there is a concern for imbalance. \$\endgroup\$ – Sunnyskyguy EE75 Sep 27 '18 at 21:12
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    \$\begingroup\$ Assume that the Mfg knows more than you until you can support otherwise. \$\endgroup\$ – Sunnyskyguy EE75 Sep 27 '18 at 21:18
  • \$\begingroup\$ I will be adding a photo soon! need to make a render of what I found..... way too complicated \$\endgroup\$ – Robert Dold Sep 27 '18 at 21:30
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    \$\begingroup\$ "negative" ... ? \$\endgroup\$ – brhans Sep 27 '18 at 23:18

The fact that you have magnets implies a brushless motor, and wye configuration is the most common. In motors, the number of magnet poles does not really correlate to the number of phases. The only real requirement is that the magnet poles must be even in number. If you are running a ten-pole motor, the magnet arrangement will be identical after each one-fifth of a revolution (72 degrees). At this point, the north and south poles will be re-aligned in the same way they were when the revolution started, so you will need five complete phases to get one revolution. You can find the term "electrical revolution" in some of the literature; In your case, it requires 5 electrical revolutions to make one mechanical revolution. So your generator output frequency will be five times higher than you would get with a two-pole generator run at the same speed. This is desirable in some cases to keep the rpms low.

Illustrations of brushless motors often show the most simple arrangement of windings and magnets so that they are easy to understand, but in practice the number of poles and the number of slots in the stator are arranged in a manner to provide the desired back emf waveform - most often sinusoidal or trapezoidal - so that they can be driven with a minimum of torque and current ripple. For instance, we manufacture 8-pole motors with 21 or 27 slots in the stator. A slot in the stator has windings from two of the three phases and the wind would certainly seem random to many, but it is really only complex. I am guessing your motor is just fine.

Good luck!

  • \$\begingroup\$ hmmm very good point! I started trying to make mine too but like you said it can be a little trickier than book smarts imply! thank you for your response sir. \$\endgroup\$ – Robert Dold Sep 29 '18 at 12:55

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