Properties and Synthesis of Lossless Snubbers and Passive Soft-Switching PWM Converters

This article investigates the synthesis of lossless snubbers and passive soft-switching converters, as well as their general properties, including topological properties and electrical properties. The aim is to find the possible simplest snubbers and soft-switching converters and to give suggestions on applications of the snubbers and the soft-switching converters. On one hand, the synthesis and the topological properties of the snubbers and the converters determine the complexity of the topologies and help find the least requirement that passive soft switching needs to fulfill. The topological properties are investigated by addressing the basic issues induced by the inductor/capacitor added for passive soft switching. Based on the topological properties, the snubbers and the converters are synthesized. On the other hand, the electrical properties determine the performance of the snubbers and converters, help understand the limitations and are investigated by two case studies accompanied with experimental verification. By investigation of the general properties, the possible simplest snubber is given, the tradeoff between the complexity and performance is discussed in detail, the suggestion of snubber applications is presented, and three kinds of reported passive soft-switching converters which are believed to have the most potential of wide application are discussed.