A Novel Common-Mode Voltage Reduction Method of MMC: Pulse Sequential Connection Carrier Phase-Shifted SPWM

The switching of the sub-modules (SMs) of modular multilevel converter (MMC) causes a common mode (CM) voltage to ground at the neutral point of the AC side of the MMC, which will affect the normal operation of the system. For instance, the CM voltage in MMC will damage the motor bearing and cause the conducted electromagnetic interference (EMI) problem seriously. In order to reduce the CM voltage in MMC, this paper proposes a novel modulation method of pulse sequential connection (PSC) carrier phase-shifted sinusoidal pulse width modulation (CPS-SPWM), under which the CM voltage of the MMC is zero theoretically. The correctness and effectiveness of the reduction method are validated by the 5-level MMC simulation platform.