Research On Bidirectional DC-DC Converter For Auxiliary Power System Of Electric Vehicle

With the development of economy,energy shortage and environmental pollution have become the two major factors that restrain the sustainable development of human beings.Vigorously developing new energy is an effective measure to solve these problems.Because of its zero emission characteristics,electric vehicles can effectively reduce environmental pollution,which is an inevitable choice for the development of the automotive industry.However,the shortcomings of short endurance mileage and high maintenance cost of batteries are two basic problems that must be solved in the development of electric vehicles.The auxiliary power system of electric vehicles composed of super capacitors and bidirectional DC-DC converters can effectively improve endurance mileage and reduce the damage to batteries caused by high current charging and discharging.Super capacitors can provide high-power energy feedback during deceleration and braking of electric vehicles through bidirectional DC-DC converters,and also provide necessary peak power compensation when starting and accelerating of electric vehicles.Therefore,the research on auxiliary power system of electric vehicles is of great significance.Firstly,the characteristics of power batteries and super capacitors are analyzed.According to the real working environment of electric vehicle,the topology of bidirectional DC-DC converter is selected.In order to improve the performance and power level of the converter,the topology of the converter is optimized.A two-phase interleaved bidirectional half-bridge circuit is selected as the main topology of the bidirectional DC-DC converter.According to the practical application environment of bidirectional DC-DC converter,small signal modeling and loop compensation are carried out for Boost mode and Buck mode of bidirectional DC-DC converter,and corresponding controller parameters are designed to make the bidirectional DC-DC converter havesufficient steady-state performance and dynamic response ability.Aiming at the problems of non-uniform current,reverse recovery and low efficiency of two-phase interleaved half-bridge circuit,the corresponding solutions are put forward.According to the design performance index,Boost mode and Buck mode are simulated in MATLAB/simulink environment respectively.The simulation results verify the good dynamic and steady-state performance of the converter.Finally,based on the floating-point controller TMS320F28069,according to the design parameters of hardware and software,a 600 W experimental prototype is built,and the performance indicators of two modes are tested.The experimental results show that the designed converter meets the design requirements.The validity of the proposed control strategy and the rationality and correctness of the selected parameters are further verified.