Analytical Technique for Designing an RC Snubber Circuit for Ringing Suppression in a Phase-Leg Configuration

Abstract

Herein, we propose an analytical technique for use in designing a resistor capacitor ( RC ) snubber circuit for suppressing ringing in phase-leg configurations that are among the main components in electric power converters. In our study, a double pulse circuit is used to examine the effects of RC snubber circuit ringing suppression because the phase-leg and double pulse configuration ringing mechanisms are the same. First, a high-frequency equivalent circuit of the double pulse circuit is derived. Next, an RC snubber circuit for ringing suppression is analytically designed by scrutinizing the characteristic equations via the root locus method. Prior to using the root locus method, we conducted an investigation to determine if that method could be used to analyze the derived high-frequency equivalent circuit when RC snubber circuit parasitic inductances and inductances between the upper and lower modules connectors are small enough to ignore. Finally, the ringing suppression effect of the RC snubber designed by using the proposed analytical technique in a double pulse circuit with practical parasitic inductance values is confirmed via circuit simulations and experimental demonstrations.