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 commonmode voltage.The purpose is not to achieve complete cancellation, but to restrict only a slope in a change of the common-mode voltage applied t o an ac motor.As a result, the core size of the common-mode transformer used in the ACC becomes small considerably.Experimental resultsshow good effects of the proposed active circuits on both ground current and conducted EMI.