Common-mode noise source and its passive cancellation in full-bridge resonant converter

In this paper the results of systematic investigation into identification of dominant source of CM noise generation in a full bridge resonant converter are presented. It is shown that a small mismatch in an apparently symmetrical circuit can result in large CM injection. Mathematical analysis to predict the CM current injection is presented and is validated using SPICE simulation. For cancellation of dominant CM injection simple passive techniques are suggested. Experimental results on 18 kW LCC resonant magnet power supply for INDUS-2 are presented to demonstrate the effectiveness of proposed passive techniques.