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An interior permanent magnet synchronous reluctance motor is more efficient than an induction motor but is it also more efficient than BLDC permanent magnet motors (of similar size)?

 

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Why would one claim the interior permanent magnet synchronous reluctance motor is more efficient than a BLDC permanent magnet motor of similar size?

 

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“From most efficient to least, here’s how the five motor technologies stack up: salient-pole PM, nonsalient PM, synchronous-reluctance, switched-reluctance and, last but not least, induction motors. Regarding power and torque density, as may be expected, the rankings mirror those for efficiency, with the PM designs having the highest torque density and induction designs the least.”

StackPath

 

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One could conclude BLDC is more efficient than synchronous reluctance, but shifting stator BLDC has more operating points than BLDC.

 

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In a brachistochrone oberth tunnel you’d want to pull the stators for sure, otherwise the rotor will make too much back emf...

 

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Did the methane and hydrogen sulfide combine to form a room temperature superconductor at high pressure?

Carbonaceous sulfur hydride - Wikipedia

en.wikipedia.org

 

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PMSM has distributed windings but Synchronous Reluctance motors have a different rotor which can substitute the permanent magnets for iron, and some including the model 3 have embedded magnets (hallbach arrays) in the iron.

synchronous reluctance iron rotor:

bldc permanent magnet rotor:

model 3 rotor with internal halbach arrays:

 

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exterior rotor (outrunner) motors have higher torque density and efficiency compared to interior rotor (inrunner) motors...

Exterior vs. interior rotors in robotic brushless motors | Request PDF

Request PDF | Exterior vs. interior rotors in robotic brushless motors | Many robotic actuators must generate high torques and accelerations. Exterior-rotor brushless motors seem better suited for these tasks than... | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

 

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So, as the man says, they are better at powering robots.

Not much relevance to EVs there.

well, the implication is an outrunner style surface permanent magnet motor can have better performance and efficiency than a interior permanent magnet synchronous reluctance inrunner style motor of the same mass - presumably since you’d be replacing the iron in the IpmSynRM rotor with more copper in the windings and more permanent magnets, and the rotor will have a larger outer diameter (without increasing the overall motor diameter) for more leverage...

 

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there seems to be considerable room for improvement, likely not only in motor efficiency but also torque density...

^the tesla seems to be doing more poorly efficiency wise with high torque at low speed...