Efficient PWM Loss Model for Multiphase PMSM with Floating Starpoint

Abstract

Pulse width modulation (PWM) is a wide-spread technique to control motor speed and torque. Higher harmonics in the PWM supply inject ripple current in the stator phases. This current distortion can cause significant additional losses in an electric machine. Therefore, it is important to consider these losses in an early stage of development. When it comes to the optimization of an electric machine, a proper model is inevitable. In this work, an efficient model for PWM losses in multiphase permanent magnetic synchronous machines (PMSM) is presented in order to be able to consider PWM losses during the optimization process. The losses are modelled based on fluxes in a dq reference frame. In order to verify the validity of the presented method, the interpolated results are compared to directly simulated points.