Research On High Efficiency ZVZCS Converter Based On Dual Half-bridge Topology

With the development of electonics technology,the high-frequency power supplies have put forward higher requirements on the conversion efficeiency and power density.Full bridge converters can realize zero-voltage switching without any additional devices.The circuit has a simple structure and high efficiency.It is widely used in high-power applications.However,the conventional phase-shifted full-bridge converter has several outstanding serious problems.First,under light load conditions,the converter cannot achieve zero-voltage switching,resulting in reducing system efficiency and higher electromagnetic interference.Second,rectification parasitic oscillations in the converter process increase the device's voltage stress and output voltage ripple.Finally,the conduction losses increase significantly during the freewheeling of the converter.The purpose of this paper is improving the topology of the basic phase-shifted fullbridge converter and achieving high-efficiency DC power supply.Based on the theory of full-bridge converter,a double-half-bridge ZVZCS converter topology is studied.Firstly,the scheme and topology structure studied by scholars are summarized,and the dual half-bridge ZVZCS converter topology to be studied in this thesis is determined.The paper analyzed the basic principles of the converter topology,operating modes,voltage gain characteristics,soft-switching implementation conditions of the forward arm switch tube and the hysteresis arm switch tube.According to the performance index,the hardware circuit is designed,including parameter calculation,device selection,and the overall structure of the converter layout design.Secondly,the model of double-half bridge ZVZCS converter is established,and the controller is designed to improve the dynamic and steady-state characteristics of the system.Finally,simulations and experiments are performed to verify the correctness of circuit theory analysis and controller design.Based on theoretical research and simulation design,a double-half-bridge ZVZCS converter with a rated power of 1k W was developed and tested and analyzed.The experimental results show that the double-half-bridge ZVZCS converter can achieve soft switching with medium load and light load,and has high efficiency.All work performances are in accordance with the preset parameters,and the converter has good dynamic and steady-state characteristics.