Differential Mode Active EMI Filter Design for a Boost Power Factor Correction AC/DC Converter

The objective of this paper is to introduce a methodology to design an active differential mode (DM) filter at the input side of ac/dc converters to cancel DM electromagnetic interference noise within concerned frequency range. The boost power factor correction ac/dc converter was taken as an example for DM active filter design. The active filter is analyzed based on the developed DM noise model. The design of DM active filter to achieve desired insertion gain and stability is addressed in detail. Both simulations and experiments were conducted to validate the proposed methodology. It is found that the proposed design methodology can meet the design objective and the stability challenge for the DM active filter of ac/dc converters.