The loss calculation of RCD snubber with forward and reverse recovery effects considerations

This paper addresses the problem of turn-off and turn-on performances of a RCD snubber circuit in high power inverter that works with insulated gate bipolar transistor (IGBT). The RCD snubber circuit turn-off and turn-on dynamics, forward and reverse recovery effects of the associated freewheeling and snubber diodes, and corresponding snubber losses are analyzed. Voltage impacts occur across the snubber resistor due to the snubber diode´s forward and reverse recovery effects, which bring in additional snubber losses. The turn-on current rising rates have two parts due to the anti-parallel free-wheeling diode (FWD) reverse recovery current that will influence the RCD loss. Moreover, the snubber has the same clamping effect as turn-off due to the anti-parallel FWD´s reverse recovery current. In addition, the proposed analysis was experimentally verified, the snubber loss are presented and discussed in the paper. Moreover, a well-designed temperature measurement is proposed to evaluate the loss.