Multi‐Objective Optimization and Analysis of Asymmetric Hybrid‐Magnet Offset Motor for Electric Vehicles

Abstract

Aiming at the high cost of permanent magnet synchronous motor and the reduction of motor output performance caused by high cogging torque and torque ripple, an asymmetric hybrid‐magnet offset motor is proposed. Based on the winding function theory and the equivalent magnetic circuit method, the expressions of stator and rotor magnetic potential are derived respectively, and the analytical model of torque ripple is established by combining with the Lorentz force law. By using the magnetic pole offset method, the phase offset model of the cogging torque is established, and the analytical expressions of the cogging torque and the magnetic pole offset angle are derived. The results of the simulation and experiments show that the asymmetric hybrid‐magnet offset motor has lower no‐load back‐EMF harmonic content and rare‐earth material ratio than the traditional permanent magnet motor, and its performance in terms of the cogging torque and the torque ripple is better than that of the traditional permanent magnet motor. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.