11.6 Analysis, Design, and Performance Evaluation of Flying-Capacitor Passive Lossless Snubber Applied to PFC Boost Converter

A boost converter which employs a flying-capacitor passive lossless snubber to reduce the losses caused by the reverse-recovery characteristic of the boost rectifier is described. The passive snubber consists of a snubber inductor, two snubber rectifiers, and a snubber capacitor. The losses are reduced by inserting a snubber inductor in the series path of the boost switch and the rectifier to control the di/dt rate of the rectifier during it’s turn-off. The snubber is analyzed and design guidelines are offered to achieve optimum performance. The proposed snubber is applied to a 500-W power factor corrected (PFC) boost converter which is designed to operate in the universal line range (90-264 VRMS). Performance evaluations of the proposed snubber are made and compared to the conventional boost converter with respect to efficiency and device temperature.