Design and Optimization of Asymmetrical Rotor Structure for Permanent Magnet Synchronous Motors

Permanent magnet synchronous motors (PMSMs) are widely employed in electric vehicles owing to their high efficiency, high power density, and wide speed regulation capability. However, electromagnetic vibration is aggravated by the non-sinusoidal air gap magnetic field distribution and cogging torque. To suppress vibration, this paper proposes an optimized asymmetric rotor design. Through sensitivity analysis of rotor parameters on motor performance, a high-precision Metamodel of Optimal Prognosis (MOP) is developed for the surrogate-based motor model. Subsequently, rotor parameters are comprehensively optimized using a genetic algorithm. The results demonstrate that, compared with the reference motor under identical operating conditions, the optimized motor maintains equivalent output torque while achieving significant reductions in vibration-related performance indicators: torque ripple is reduced by 17.9%, and cogging torque is reduced by 82.8%, the amplitude of the 48th-order electromagnetic force decreases from 2.60 N to 1.28 N (representing a 50.7% reduction), and the peak vibration response decreases from 109.7 dB to 107.2 dB. This study provides an effective design approach for electromagnetic vibration suppression in PMSMs.