Research On Bi-directional DC-DC Converter For Composite Power Supply Electric Vehicle

In order to deal with global warming,energy depletion and ecological crisis,people apply new energy technology in the field of electric vehicles,which to a certain extent reduces the harm caused by vehicle pollutant emissions,so the development of electric vehicle industry is rapid.DC-DC(direct current direct current)converter is the energy conversion medium of electric vehicle hybrid energy storage system,which plays an important role in improving the driving range,acceleration ability and stability of electric vehicle.In this paper,the control strategy of bi-directional DC-DC converter is studied as follows:Firstly,the topology and parameters of DC-DC converter are determined.After analyzing the characteristics of different kinds of DC-DC converters and DC-DC converters needed by vehicles,such as power,stability,implementation difficulty,cost and other factors,two-phase interleaved parallel connection is selected The buck /boost half bridge structure is the research object of this paper.According to the connection topology of energy storage elements and energy consumption elements in the hybrid energy storage system,the power demand indexes in different energy flow directions are determined,and the parameters of the main elements of the converter and the appropriate circuit elements are determinedSecondly,the circuit model of Buck / boost is built,and the adaptive fast terminal sliding mode control strategy is designed for simulation.According to the change of input voltage,load resistance and reference voltage,the boost / buck circuit model is built respectively.For each mode,the adaptive fast terminal sliding mode algorithm is designed and compared with PID and second-order sliding mode control algorithm.The simulation results under different conditions are obtained and analyzed.Thirdly,particle swarm optimization algorithm is designed to optimize the parameters of the controller.Different control parameters have different control effects.In order to obtain better voltage output characteristics,PSO optimizes the parameters of the adaptive fast terminal sliding mode control strategy and simulates it.Finally,based on STM32 as the control core,the bi-directional DC-DC converter experiment platform is built,debugged,calibrated the sensor data,tested the steadystate performance and dynamic performance of the converter,and compared the simulation results with the experimental results to verify the feasibility of the design strategy.