Design of output passive EMI filter in DC-fed motor drive

This paper focuses on the conducted electromagnetic interference (EMI) noise suppression solution at the ac output terminal of PWM motor drives. Dc-fed voltage source inverter (VSI) is selected as one typical topology. A practical output EMI filter design procedure is proposed. To ensure design accuracy, the procedure includes the system impedance characterization with offline measurement. Meanwhile, different damping methods are studied to avoid oscillation introduced by EMI filters. Prototype experimental results have verified the feasibility of the design procedure for both common-mode (CM) and differential-mode (DM) EMI noise suppression.