Design of an active differential mode current filter for a boost power factor correction AC-DC converter

The aim of this paper is to introduce a methodology to design an active DM filter at the input side of AC-DC converters to cancel current ripples and DM EMI noise. The boost PFC AC-DC converter's noise characteristic was first analyzed. The active filter topologies are designed based on the identified characteristics of the AC-DC converters. Several design issues such as thermal run away, DC offset, stability and compensation design, and the number of preamplifier stages are to be 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 big stability challenge for the DM active filter of AC-DC converters.