Circuit configurations and performance of the active common-noise canceler for reduction of common-mode voltage generated by voltage-source PWM inverters

This paper discusses two different circuit configurations of the active common-noise canceler (ACC) which has been proposed by the authors. One is characterized by its DC power supply isolated from the DC link of a PWM inverter. The configuration makes it possible to integrate the ACC with a medium-voltage PWM inverter. The other compensates a partial frequency component of the common-mode voltage. The purpose is not to achieve complete cancellation, but to restrict only a slope in a change of the common-mode voltage applied to an AC motor. As a result, the core size of the common-mode transformer used in the ACC becomes considerably small. Experimental results show good effects of the proposed active circuits on both ground current and conducted EMI.