An Efficient Snubber Circuit for Soft-Switched Capacitive-Link Universal Converters

This paper proposes a snubber circuit for a newly introduced soft-switched capacitive-link universal converter. This snubber circuit can be used in a wide range of converters that have a discrete inductance in series with a semiconductor switch in the small signal model of the converter, and this paper focuses on using it in soft-switched capacitive-link universal converters given their promising features, including very high power density and long lifetime. The proposed snubber circuit not only eliminates the voltage ringing across the switches, but also significantly lowers power losses compared to the conventional RC snubbers. A comprehensive analysis is carried out in this paper to compare the proposed snubber circuit with conventional RC snubbers. In particular, the efficiency and the ability of these snubber circuits to suppress voltage ringing/spike across the switches are compared. Moreover, the operation of the proposed snubber is experimentally evaluated in a dc-to-three phase ac capacitive-link universal converter.