RCD snubber revisited

The use of the polarized RCD turn-off snubber configuration across switching devices is popular because of its simplicity and use of only passive components. This configuration is limited by the fact that all capacitor-stored energy is dissipated in the discharge resistor. In this paper, it is shown that with the addition of a ferrite transformer to the standard RCD arrangement, in excess of 70% of the energy stored on the snubber capacitor may be passively recovered into the DC supply. Performance of this passive recovery snubber is supported by theoretical, simulated and practical results.