Hight Efficiency Selectively Activated Resistor-MOSFET Snubber Based on MOSFET Voltage Sensing

The rapid adoption of electric vehicles has increased the demand for miniaturized power conversion systems with weight reduction features. Although increasing the switching frequency enable downsizing of the passive components, the high-frequency resonance between the MOSFET’s output capacitance and parasitic inductance induces severe voltage ringing. Conventional RCs, LCs, and active snubbers can mitigate those side effects but suffer from excessive loss, increased volume, and control complexity. This study proposes a snubber topology that replaces the snubber’s capacitor with a MOSFET, thereby reducing the equivalent capacitance and power losses in the snubber. An integrated overvoltage detection circit at the MOSFET gate driver actively damps ringing and secures precise voltage regulation. Experimental validation on a 60 W flyback converter demonstrated a power loss reduction of 0.3-0.6 W in the snubber circuit compared with that of conventional RC snubber, alongside enhanced voltage control performance. The proposed snubber circuit thus offers a compact and high efficiency solution for high frequency power converters.