Research On SEPIC High Frequency DC/ DC Power Converter

With the rapid development of the power industry,high power density power converters have been gaining more and more applications in many applications.Therefore,in the power electronic technology,the research of high frequency and very high frequency power converters of small size,light weight and high efficiency is particularly important.Thus,this paper is devoted to the study of a resonant SEPIC type high frequency power converter.The main research contents are as follows: the structure and working principle of main circuit topology,design method of resonant drive and calculation of loss,the research on control strategy.In the study of resonant type SEPIC high frequency power converter,it is necessary to divide the main circuit topology into three parts: resonant rectifier,matched network and resonant inverter.Firstly,the resonant rectifier of the main circuit,comparing the voltage and current type resonant,and analyzing how to use the parameter scanning method to obtain the ideal circuit parameters quickly.Thus,the function and parameter design method of matching network in high frequency circuit are discussed.Finally,the influence of the input and output impedance on the ZVS characteristics of the switch is discussed by means of the impedance analysis method,and the ZVS is realized in the simulation and prototype test.The traditional totem pole driver will have a large gate loss in the high-frequency power converter.So in recent years,resonant drive has gradually become a high-frequency drive research hotspot.In this paper,the development process of resonant drive is analyzed,and the loss caused by the basic resonance drive and the totem pole drive at high frequency is compared.And the basic resonant drive circuit has been improved to further enhance the efficiency of the system.Meanwhile,the Burst control strategy is optimized so that the system can achieve the fastest transient response speed,deriving the transfer function of the closed-loop system,judging the stability of the system.A 20 MHz and 5W laboratory prototype was built,collecting the experimental waveforms to verify the correctness of the experimental results and the feasibility of the theoretical analysis.