Series-Connected Grounding of Common-Mode EMI Filter

Due to the effects of parasitic inductance, the common groundline (CGL) of capacitors in common-mode (CM) electromagnetic interference (EMI) filter is influential to filtration performance of the filter. In this paper, the effect of a single-point grounding method of CM EMI filter is first analyzed, and then, in order to eliminate the negative effect of CGL, a series-connected grounding method is introduced and analyzed. The effectiveness of the series-connected grounding method on improving the performance of CM EMI filter with CGL is verified through experiment.