Research on characteristics of common-mode voltage in PWM drive system and its cancellation

Pulse width modulated (PWM) inverter can generate common-mode voltage (CMV) which will decrease the system reliability. Firstly, some theoretic analysis and experimental results validate the characteristics of CMV and its adverse effects in this paper, and the methods for its cancellations are also presented. Then a novel inverter output active filter based on a single-phase inverter and a five-winding transformer is proposed, utilizing the reconstructed inverse CMV inserted into the motor leads to cancel CMV at motor terminator. Its scheme, control principle, design guidelines are also presented. Finally, experimental results prove its effectiveness in eliminating CMV in the PWM inverter driving systems.