Modeling and Stability Analysis of Digital EMI Filter

Smaller size and lower loss are always the target of EMI filter which suppresses EMI emitted by power electronics converter. Digital EMI filter (DEF) is the best solution to suppress the conducted EMI in size and loss, especially for highpower converters. However, for current DEF model, it is not enough to describe the filtering ability. The model which can describe DEF stability is absent. To cope with these, this paper proposes a modeling technique about filter and stable behavior of DEF system. In proposed technique, the insertion gain model can accurately describe the filtering behavior, and the loop gain model can predict the stability of DEF system. Experimental testbed based on a Boost converter as EMI interference is built. Experimental results validate that the proposed model can successfully predict the stability and performance of DEF system.