Soft switching active snubbers for DC/DC converters

A soft switching active snubber is proposed to reduce the turn-off losses of the IGBT in a current-mode controlled buck power converter. The soft switching snubber provides zero-voltage switching for the IGBT, thereby reducing the high turn-off losses of the IGBT 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 low EMI and an improved RBSOA. The use of an active snubber allows recovery of part of the energy stored in the snubber capacitor during the turn-off. Finally, a generic snubber cell is identified for all the nonisolated DC/DC power converters (buck, boost, buck-boost, Cuk, Sepic, Zeta)