Research On CDR-based ZVS Three-Transistor Push-pull Converter

With the development of DC/DC converter,research on soft-switching technology of DC/DC converter have been carried out much more and deeply.The soft-switching technology can reduce device stress,switching loss,electromagnetic interference(EMI)and improve power density of the power electronic equipment.In this area,most of the research has been done based on phase-shifted full bridge converter.However,push-pull converter has the advantages of simple structure,more used in large current input cases.There is also a lot of research on the soft-switching technology of push-pull circuit.For example,the push-pull forward converter;push-pull converter with resonance net;the active-clamped push-pull converter etc.This paper make research on a current-double-rectifier based ZVS Three-Transistor Push-Pull converter.This circuit is to add one transistor between the input voltage and the midpoint of the transformer at the primary side,and use current-double-rectifier circuit at the secondary side.The proposed topology is simple.Its main transistors can achieve ZVS under wide load range and turn-off under half the current occurred in traditional push-pull converter.The article describes the principle of how this proposed converter works with detail.And analyze the principle of the ZVS of the main transistor and the added transistor.The passage also tells how to design the components and verified the discussed theory correctly by experimental results.Based on the limit of the added transistor ZVS accomplishment,another current-double-rectifier based ZVS Three-Transistor Push-Pull converter with a blocking capacitance is proposed.Once again the article describes the principle of how this proposed converter works with detail.And analyze the principle of the ZVS of the main transistor and the added transistor.Using experimental results to verify the discussed theory correctly.At last the paper compared similarity and difference of the CDR-based ZVS Three-Transistor Push-Pull converter and CDR-based phase-shifted full bridge converter.