Reduction of On-Load Torque Ripple in PMSM Using Time-Space Harmonics Analysis of Air-Gap Flux Density

The on-load torque ripple reduction for permanent magnet synchronous machine (PMSM) has always been concerned by designers. This article proposes optimal step-skew method based on the theory of time-space harmonics analysis of air-gap field, and summarizes the essential reason why on-load torque ripple has not always reduced by the step-skew angle at no load. On this basis, the 12th-order harmonic torque for a 48-slot 8-pole and 12-slot 10-pole PMSM that mainly contribute to the on-load torque ripple can be suppressed by the combination of segmented skewed poles and suitable pole-arc coefficient, so as to reduce torque ripple and improve the torque performance.