Research And Development Of Bidirectional Resonant DC/DC Converter Based On SiC Power Device

With the development and utilization of renewable energy and the development of electric vehicles,bidirectional DC/DC converter as a bridge of energy transmission has become a research focuses in recent years.In the field of renewable energy generation and electric vehicle charging and discharging,bidirectional DC/DC converters are usually used in high voltage and high power applications.However,the performance of traditional silicon(Si)material devices are weak in these situations due to their material demerits.And the new silicon carbide(SiC)material devices can replace traditional silicon(Si)material devices to achieve high efficiency and reliability because of their high voltage resistance,low on-resistance and low switching loss.Therefore,this paper combines the merits of SiC MOSFET and bidirectional resonant DC/DC,studies and designs a bidirectional resonant DC/DC converter based on SiC MOSFET for its application in the field of electric vehicles.Firstly,the symmetric CLLC bidirectional resonant converter is selected as the research object of this paper by analyzing the different topologies of the bidirectional DC/DC converter.Then,the working principle of the resonant converter is introduced,the steady state modeling analysis of the converter is carried out by the First Harmonic Approximation(FHA),and the influence of the resonant parameters on the voltage gain is analyzed according to the steadystate voltage gain.Finally,the design method of resonant parameters is deduced.Then the resonant parameters are designed according to the design specifications of the converter.Aiming at high voltage and high frequency application,the resonance inductance and high frequency transformer is designed,the selection of power device is introduced.And then the main loss of the whole converter is analyzed.Finally,the digital control system of resonant converter is designed,which mainly includes the design of hardware circuit such as SiC MOSFET drive circuit,system sampling circuit and the design of system software program.Finally,a software simulation platform is built in MATLAB/Simulink to simulate and verify the designed resonant converter,and the corresponding experimental prototype is made.The simulation and experimental results show that the converter can work steadily under different operating conditions and has good efficiency,which verifies the correctness of the analysis and design in this paper.