A Study on a Carrier Based PWM having Constant Common Mode Voltage and Minimized Switching Frequency in Three-level Inverter

Abstract

In this paper, a carrier-based pulse with modulation (PWM) strategy for three-phase three level inverter is dealt with, which can keep the common mode voltage constant with minimized switching frequency. The voltage gain and the switching frequency in overall operating ranges including overmodulation are investigated and the analytic equations are presented. Finally, the leakage current reduction effect is confirmed by carrying out simulation and experiment. It will be pointed out that the leakage current cannot be perfectly eliminated because of the dead time.