A common-mode voltage reduction in converter-inverter system by shifting active space vector in a sampling period

This paper proposes an advanced PWM method that can reduce the common-mode voltage in three-phase PWM converter-inverter systems. By the proper distribution of the zero-voltage vector of the inverter, it is possible to cancel out a common-mode voltage pulse in one control period. Since the proposed PWM method maintains the active voltage vector, it does not affect the control performance of the converter-inverter system. Without any additional hardware, the overall common-mode voltage can be decreased by one-third theoretically, compared with a conventional symmetric PWM scheme.