Acoustic Noise Analysis of Interior Permanent Magnet Synchronous Machine for Electric Vehicle Application

This paper analyses the electromagnetic resulted acoustic noise of an interior permanent magnet synchronous machine (IPMSM). The influences of electromagnetic nonlinearity, pulse-width-modulation (PWM) and motor frame on the acoustic noise are considered. A finite element model is used to extract the look up tables (LUTs) of flux linkage and air gap electromagnetic force distributions as functions of rotor positions and excitation currents. Based on the generated LUTs, an electrical dynamic model is used to simulate stator current and air gap electromagnetic force waveforms considering PWM. Simulated forces are fed to a lumped parameter mechanical model to predict the acoustic noise of the IPMSM in a wide operation range. In the end, a structural method and a PWM based method are proposed to reduce the noise level of the IPMSM. Simulation results show changing the frame thickness and adopting a different PWM method can effectively mitigate the noisy operating points.