A Full-bridge DC-DC Converter With Wide-range ZVS

With the continuously development of the auto industry,the automotive electric equipment and electronic control equipment are more and more applied in cars.As well as the electric vehicles powered by the vehicle power batteries,compared with the traditional cars,it is more clean and environmental protection.Vehicle power is more and more important in automobile industry.At present,automotive electrical equipments mainly use the vehicle batteries as their power supply.The battery is mainly charged through the DC-DC converter,which is used to convert the input voltage to the appropriate output voltage level in order to meet the demand of the battery charging in different voltage levels.Therefore,the research on the high efficieny,high power density DC-DC converter will be beneficial to the development of automobile industry.Firstly,the working process of the phase-shift control ZVS PWM full-bridge converter is introduced,and the soft-switching conditions of the leading-leg switches and lagging-leg switches,secondary side duty-cycle loss and other issues are analyzed.Then the principle and characteristics of LLC resonant converter are presented.An auxiliary LLC resonant circuit is applied to the lagging-leg of the converter by using the bridge arm sharing technology.A full-bridge DC-DC converter with wide-range ZVS is proposed,and the working state is analyzed in detail.The proposed converter have the advantages of more wide load range soft-switching,low conduction losses during the freewheeling phases,energy transfer by parallel sources.On this basis,the third chapter uses PSIM simulation software to test the proposed converter.In the fourth chapter,the hardware design and software realization of the full-bridge DC-DC converter with wide-range ZVS are presented.Finally,according to the designed parameters,a 2kW experimental prototype is built to verify the proposed converter.The experimental results show that the wide range soft-switching PWM DC-DC full-bridge converter can achieve the soft switching with 10%load to full load range and has high efficiency.The correctness of theoretical research and parameter design is verified.