Research On Design Of Resonant Converter For Wide Output Voltage Range

In order to cope with climate change,electric vehicles are being paid more and more attention from all over the world.In recent years,the charging infrastructure of electric vehicles in China has developed rapidly,in which fast charging is one of the most important charging methods.Fast charging equipment,commonly known as DC charging pile,is usually composed of three phase rectifier and DC/DC converter.The DC/DC converter is used for matching the rectifier output and the power battery,then the electrical isolation is realized.The DC/DC converter needs to meet the requirement of wide output voltage range and has high conversion efficiency.The design method of the resonant converter with wide output voltage range is studied in this paper.Firstly the development of EV charger is reviewed,the two stage structure of the AC/DC rectifier and DC/DC converter of the EV charger module is introduced,and DC/DC topology are compared,the influence of the wide range of battery voltage brought to the DC/DC converter is discussed.Then the working state of the LLC resonant converter under different modes is analyzed,as well as the loss break-down.The loss distribution of different design schemes of 'two segments'and 'three segments'under wide output voltage range is compared.On the basis of the comparison between these two charge schemes,an improved charging scheme of 'three segments' is emphatically discussed.On the basis of previous work,the design method of LLC resonant converter with wide output voltage range is summarized and verified by experimental model of 10kW.