Fully Automatized PWM Harmonics Analysis and Loss Calculation in Multiphase PMSM with Floating Starpoint

A very simple and therefore wide-spread way to control motor speed and torque is to regulate the stator voltage by pulse width modulation (PWM). Depending on the modulation type, number of inverter levels and modulation index of the PWM, various spectral components occur in the supply signal and inject ripple current in the motor phases. This current distortion can cause significant additional losses in the stator and rotor core, permanent magnets and windings of an electric machine. Therefore, it is important to consider these losses in an early design stage. In this work an efficient calculation method for harmonics of multilevel PWM signals and generated phase currents with different modulation types is presented. The PWM losses are calculated via 2D finite element method (FEM) analyses. The calculation and simulation workflow is realized within the software tool SyMSpace and applied to a three-phase permanent magnetic synchronous machine (PMSM).