Evaluation of PWM Methods for Suppressing Circulating Current among Parallel-Connected Four-Pole Inverters

Abstract

This paper investigates the effects of pulse width modulation (PWM) on the circulating current of parallel-connected four-pole inverters (FPIs). Detailed mathematical modeling shows that the common-mode voltage (CMV) outputs of PWMs are closely related to the circulating current, so this research presents the reduced CMV PWM techniques for FPIs to reduce the circulating current, and compares their performances with the conventional PWM schemes. This study also shows how the controller structure of FPI affects the use of PWM schemes and the resulting circulating current. Laboratory test results are provided to validate their effectiveness.