Passive lossless snubbers for DC/DC converters

Abstract

Passive lossless snubbers are proposed to improve the turn-on and turn-off transients of the MOSFETs in PWM DC/DC power converters. Switching losses and EMI noises are reduced by restricting the di/dt of the reverse recovery current and the dv/dt of the drain-source voltage. The MOSFET operates at ZVS turn-off and near ZCS turn-on. The freewheeling diode is also commutated with ZVS. As a demonstration, operation principles, theoretical analyses, relevant equations and experimental results of a boost power converter equipped with the proposed snubber are presented in detail. An efficiency of 96% has also been measured in the experimental results reported for a 1 kW, 100 kHz prototype in the laboratory. Six basic nonisolated PWM DC/DC power converters (buck, boost, buck-boost, Cuk, Sepic and Zeta) equipped with the proposed passive lossless snubbers are also shown in this paper.