Spatial-Harmonic Modeling and Analysis of High-Frequency Electromagnetic Vibrations of Multiphase Surface Permanent-Magnet Motors

This article introduces a spatial-harmonic model for analyzing high-frequency vibrations induced by PWM-current harmonics in inverter-fed surface permanent magnet synchronous motors (PMSMs). The model provides a fresh perspective on calculating the high-frequency vibrations of motors with a fixed inverter switching frequency. Electromagnetic (EM) forces along stator boundaries are first calculated utilizing the permeance distribution function. Then, the concept of spatial-order-excitation transfer functions is introduced to facilitate the modelling of the motor vibrational response under distributed excitation forces. Two approaches to obtain spatial-order-excitation transfer functions (SOETFs) are subsequently investigated, one by finite-element analysis while the other by experimental identification. Finally, high-frequency vibrations predicted by the proposed model are validated by experiments, showing a high degree of accuracy.