High-frequency Soft Switching Technology Research And Application

Some kinds of special power supplies which need to output high power, large current or high voltage and work in special circumstances, are required small volume, light weight, less heat dissipation and EMC. The high-frequency soft switching technology applied to the special power supplies has predominant advantages:higher switching frequency, less volume and weight, less switching energy loss, better EMC and better the performance of semiconductor devices.There are two kinds of typical circuits in the high-frequency soft switching technology applied to high power special power supplies:the full-bridge phase-shifted soft switching circuit and the full-bridge series resonant soft switching circuit. The former is usually applied to power supplies that output high power and high current with less on-state loss and higher efficiency. The latter is usually used in the charging power supplies of high voltage pulse capacitors with constant current output characteristic and high capability of anti-short-circuit.The working process of the two kinds of circuits, the principles of achieving soft switching and their problems are analyzed. Some measures are proposed and two power supplies are developed in the paper. The content is divided into two parts:(1) The working process of the full-bridge phase-shifted soft switching circuit and the ZVS problem of the lagging leg are analyzed in detail. A saturable inductor, in stead of a linear inductor, is used to solve the ZVS problem of the lagging leg, and the working process and the principle are studied. The influence of switches’parallel capacitors on switching energy loss is researched. On the base of these studies, a5kW experimental prototype is developed in the paper.(2) The working process and the principle of the full-bridge series resonant soft switching circuit are studied. The conditions and advantages of its constant current charging characteristic are analyzed. On the base of these studies, A series resonant charging power supply applied to high-voltage pulse generator system is developed in the paper.