Torque Ripple Reduction Design Approach of Permanent Magnet Machines Based on Circumferential Pole Pair Shift

To tackle the torque pulsation challenge in permanent magnet machines (PMMs), this article proposes two design methods that involve shifting the permanent magnet pole pairs. Method 1 circumferentially shifts half of the pole pairs by half of the most significant pulsation period, while Method 2 shifts multiple pole pairs, with the angle of pole-pair displacement gradually increasing and evenly distributed over one selected pulsation cycle. Through the finite-element method (FEM) of various case studies with diverse pole-slot combinations, it is demonstrated that both proposed methods effectively suppress torque ripple, reduce cogging torque, and optimize back electromotive force distortion.