Implementation of a novel active common-mode filter used in DC-DC converters

This paper proposed a novel active common-mode filter to suppress common-mode (CM) electromagnetic interference (EMI) in DC-DC converters. Common-mode coupled paths analysis and CM modeling analysis of a DC-DC converter is presented, firstly. Then analytical and experimental results are presented for a novel active EMI filter (AEF). The filter includes a current transformer for sensing a common mode signal, an output and an active circuitry for producing an offset signal on the output. By real time dynamic control of the active filter, the gain of the whole system could acquire the maximum value. This filter is suitable for input smoothing and integration in DC-DC converters.