Quasi-Resonant Passive Snubber for Improving Power Conversion Efficiency of a DC-DC Step-Down Converter

Abstract

A quasi-resonant passive snubber for the conventional dc-dc step-down converter is proposed. The snubber uses six passive components to achieve a zero-current turn-ON and zero-voltage turn-OFF of the switch, and to suppress the reverse recovery current of diode. At input voltage of 200 V, output voltage of 100 V, output power of 300 W, and switching frequency of 190 kHz, the snubber increased the power conversion efficiency eta(e) by 2.8% and stabilized the temperature of MOSFET switch at similar to 68 degrees C. The snubber worked well for both MOSFET and insulated gate bipolar transistor (IGBT) switches without increasing the voltage stress. These experimental results show that the proposed snubber is very helpful for improving eta(e) of a dc-dc step-down converter that operates at a high frequency.