A three-phase voltage-source PWM inverter system characterized by sinusoidal output voltage with neither common-mode voltage nor normal-mode voltage

This paper deals with an inverter system integrating a small-rated passive EMI filter with a three-phase voltage-source PWM inverter. The purpose of the EMI filter is to eliminate both common-mode and normal-mode voltages from the output voltage of the inverter. The motivation of this research is based on the well-known fact that the higher the carrier or switching frequency, the smaller and the more effective the EMI filter. An experimental system consisting of a 5-kVA inverter, a 3.7-kW induction motor, and a specially designed passive EMI filter was constructed to verify the viability and effectiveness of the EMI filter. As a result, it is shown experimentally that both three-phase line-to-line and line-to-neutral output voltages look purely sinusoidal as if the inverter system were an ideal variable-voltage, variable-frequency power supply when viewed from the motor terminals. This results in complete solution of serious issues related to common-mode and normal-mode voltages produced by the inverter. (C) 2003 Wiley Periodicals, Inc.