Torque Ripple Reduction for Interior Permanent Magnet Synchronous Machines under Load Excitation by Optimizing Rotor Skew Angles

This paper presents a skew angle optimization method to reduce torque ripples for an interior permanent magnet synchronous machine (IPMSM) under load excitation. Single- and multi-objective optimizations are employed to maximize the output torque and/or minimize the torque ripple for an IPMSM with four-step linear rotor skew. The motor model is based on look-up tables. The rotor skew angle vector is optimized for priority operating points in both constant-torque and constant-power regions of the torque-speed map. It is found that the output torque and torque ripple can be balanced to meet the targets of the output torque quality and the voltage constraint. Both two- and three-dimensional finite element analyses are used to verify the optimized results.