High-frequency modeling based EMC performance improvement of power supplies in inverters

In high power PWM inverters, the stability of the auxiliary power supplies makes great contribution to the reliability of the inverters. This paper deals with the EMI (Electromagnetic Interference) problem of the auxiliary power supplies which is caused by the high-frequency switching power electronic devices. Firstly the high-frequency models of the three phase inverter and the auxiliary power supplies are given. Meanwhile the common-mode voltage of the inverter is calculated in detail. Based on the models, the conduction routes of the interferences are illustrated. The analysis shows that the common-mode voltage interferes the stability of the auxiliary power supplies through three conduction routes. Finally, methods that can suppress the EMI on power supply voltages are proposed and verified by simulation and experiment.