Study on the effects of rotor-step skewing on the vibration and noise of a PMSM for electric vehicles

Radial force Fr is the main cause of electromagnetic vibration and noise in motors. In this study, the vibration and noise characteristics of a permanent magnet synchronous motor (PMSM) with consideration of rotor-step skewing are investigated. Firstly, the analytical model of Fr considering rotor-step skewing is deduced based on the Maxwell stress tensor method. The influence of rotor-step skewing on Fr of the PMSM is then analysed and summarised. Taking a 65 kW PMSM commonly used in electric vehicles as an example, combined with electromagnetic finite element analysis, Fr is then evaluated. Secondly, an electromagnetic vibration and noise simulation analysis is conducted based on a multi-physical field joint simulation platform, from which the influence of rotor-step skewing on the vibration and noise is then summarised. Finally, a noise experiment is then carried out. The results obtained from the multi-physical analysis and the tests conducted are presented to validate the precision of the simulation models, and the accuracy of the analytical model of F-r.