Research and realization of a novel active common-mode EMI filter

Voltages and currents of high power density power electronic circuits vary rapidly for its high speed switching, which results in serious electromagnetic interference (EMI) problems. The conventional used EMI filters are made of passive inductors and capacitors. Its size is usually comparable to that of the converter itself. As to this, active EMI filters (AEF) made of amplifiers and transistors are proposed. In this paper, a novel AEF topology used for DC-DC power converters is proposed. The most distinguished feature of this filter is that it shares the same power supply with the DC-DC converter. Thus, the size and weight of the whole filter is reduced to a great extent. The experimental results show that the proposed filter worked well and could attenuate the noise with high effectiveness.