BLDC and odd vs. even number of poles 2

[hyboxis79]

A question that boggles me about BLDC poles is that I've noticed some cases of BLDC's with odd numbered poles like 9 for example, Aren't they supposed to come in pairs so the flux can always have a straight line to "flow" to, and an exclusive opposite pole?

 

[waross]

Is that 9 poles or 9 pole pairs? Poles sometimes refers to pole pairs instead of individual poles. Confusing, yes.
(A 2 pole induction motor will actually have 6 individual poles. 1 pair for each of 3 phases.)

Bill
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"Why not the best?"
Jimmy Carter

 

[cswilson]

I've been in the servo business for about 25 years now, and never seen a motor specified to have an odd number of poles. I agree with your instincts that you must have a matching number of north and south poles on the rotor. Like waross, I wonder if the specification was for number of pole pairs.

Curt Wilson
Delta Tau Data Systems