[yarross]

Induction motors may be more effcient when operating in deep weakening region. Reason - their excitation current decreases, and for PMACs' counterexcitation current increases when going deeper into weakening.

 

[yarross]

Uhm keep in mind, that "alternator style" means claw pole synchronous machine. Maybe you've meant just classic synchronous machine, with electromagnetic excitation?

 

[yarross]

Then again, what benefit, other than power factor correction, does a wound rotor have over a pure induction machine?

Better power density and no pullout torque limit?

 

[yarross]

Power density appears to be very misunderstood concept on this forum in electrical rotating machines since it relies on the operating speed range. Torque density is more appropriate.

samborambo: I'm talking about 1:1 comparison of induction and synchronous motors, both having the same stator and operational speed. For this case, power density ~ torque density. By freeing the stator from the need of providing excitation to the rotor, one can obtain significantly higher torque.

Pull out torque for induction machines is usually only apparent when driven from V/Hz controllers or straight online utility frequency.

By "pullout torque limit" I meant limited span of constant power region, due to falloff of pullout torque. For synchronous machines, this region is somewhat extended.

 

[yarross]

I can't see how that's possible. BEMF for a BLDC will keep increasing above base speed.

Ehm we were talking about induction motor vs wound rotor synchronous one. This makes the difference.