Passive Cancellation for Reducing Input- and Output-Side Common-Mode Currents in Three-Phase PWM Inverter-Fed Motor Drive Systems

This paper proposes passive cancellation method for reducing input- and output-side common-mode (CM) currents in pulse-width-modulation inverter-fed motor drive systems. In the proposed method, three CM transformers (CMTs) are connected to each input- and output-side of the inverter, respectively. By selecting the turn ratio of each CMT with taking the stray capacitances of the inverter into account, the input- and output-side CM noise can be suppressed simultaneously. The measured CM currents in the motor drive system validate that the proposed method achieves -30.7 dB attenuation at input-side and -36.5 dB attenuation at output-side.