Soft switching active snubbers for DC/DC converters

A soft-switching active snubber is proposed to reduce the turn-off losses of the insulated gate bipolar transistor (IGBT) in a buck converter. The soft-switching snubber provides zero-voltage switching for the IGBT, thereby reducing its high turnoff losses due to the current tailing, The proposed snubber uses an auxiliary switch to discharge the snubber capacitor. This auxiliary switch also operates at zero-voltage and zero-current switching, The size of the auxiliary switch compared to the main switch makes this snubber a good alternative to the conventional snubber or even to passive low-loss snubbers, The use of the soft-switching active snubber permits the IGBT to operate at high frequencies with an improved RBSOA, In the experimental results reported for a 1 kW, 40 kHz prototype, combined switching/snubbing losses are reduced by 36% through the use of the active snubber compared to a conventional RCD snubber, The use of an active snubber allows recovery of part of the energy stored in the snubber capacitor during turn-off, The generic snubber cell for the buck converter is generalized to support the common nonisolated dc/dc converters (buck, boost, buck-boost, Cuk, sepic, zeta) as well as isolated dc/dc converters (forward, flyback, Cuk, and sepic).