Automated Design Method for Sine Wave Filters in Motor Drive Applications with SiC-Inverters

This work describes a design method for sine filters used for servo motor drive applications with a two level voltage source inverters (VSI) with 1200V SiC MOSFETs. To assess the filter effectiveness in attenuating conducted EMI emissions a worst case distortion spectrum of a PWM modulated half bridge midpoint voltage is calculated. The filter and the drive system are transformed to single phase differential (DM) and common mode (CM) equivalent circuits (EQC). The implemented algorithm enables parameter studies with various filter topologies, drive systems and values of filter components. The result of an example parameter study is analyzed and a suitable filter is built up and measured. The measured filter is then compared to the design results and the deviations are discussed.