On discussion of AC and DC side EMI filters design for conducted noise suppression in DC-fed three phase motor drive system

This paper discusses EMI filter design methodology for DC-fed three-phase motor drive system. An analysis of noise source and propagation path impedances of motor drive systems is conducted, a new filter design model for both AC side and DC side filter is proposed based on the impedance mismatching between the EMI filter impedances and noise source/load impedances. Using this model, the in circuit attenuation of EMI filter can be accurately predicted. The interaction between AC and DC filters is also studied in this analysis. By applying some constraint, EMI filters can be designed. This new design procedure is suitable for both DC and AC side EMI filters. Simulation and experimental results give a firm support to the proposed method.