IEEE Transactions on Energy Conversion, Vol.26, No.1, 55-63, 2011
Torque Analysis in Permanent-Magnet Synchronous Motors: A Comparative Study
This paper examines the torque ripple and cogging-torque variation in permanent-magnet synchronous motors (PMSMs). The effect of slot number and magnet skewing on electromagnetic motor torque, has been analyzed in different 20-pole, three-phase, PMSM configurations having the same envelop dimensions and output requirements. Finite-element technique is used for machine characteristics computation. Maxwell-stress tensor is used to find torque. Finite-element analysis results show that: 1) motors with fractional-slot winding have lower torque ripple but show a reduction of the average torque and 2) in step-skew magnet motors, torque-ripple reduction is significant only for a certain step number and magnet-skew angle.
Keywords:Cogging torque;fractional-slot windings;magnet skewing (step-skew);permanent magnet synchronous motors (PMSMs);torque ripple