Study On Power System And Control Strategy Of 48V Hybrid Vehicle

With the continuous updating of China’s fuel consumption regulations and the introduction of the double points policy,the development of new energy vehicle technology in China has been promoted.Pure electric vehicles are the ideal goal for automobiles.However,the development of pure electric vehicles is limited by the problems of inconvenient charging and high cost of pure electric vehicles.Hybrid vehicles with dual power sources of engine and electric motor can reduce fuel consumption and the adverse effects of long charging time,so the research on hybrid vehicles is in the ascendant.48 V hybrid vehicles are micro-hybrid vehicles,which do not require significant modifications to the original vehicle.The research and development cycle is short and the cost is low.In this paper,a 48 V hybrid vehicle powertrain parameter matching and control strategy study is conducted based on a fuel vehicle.Different transmission modes are compared,and the P2 configuration is determined as the transmission mode of the 48 V hybrid vehicle power system under the consideration of fuel saving rate and brake recovery.According to the power index of 48 V hybrid vehicle,the types of motor and battery of 48 V hybrid vehicle power system are determined,and the power parameters such as battery capacity,motor speed and power are matched and calculated according to the knowledge of automotive theory and other factors.Based on the demand driving torque,braking torque and the relative remaining battery charge(SOC)to determine the six operating modes of starting,motor drive alone,engine drive alone,hybrid drive,travel charging and regenerative braking.The logic threshold method is used to develop the whole vehicle drive and whole vehicle braking control strategy,and the simulation model of the control strategy is built using Matlab/Simulink.The 48 V hybrid vehicle and the reference fuel vehicle models are built in Cruise software.Two operating conditions,NEDC and WLTC,are selected for joint simulation with Matlab/Simulink to analyze the operating conditions of the 48 V hybrid vehicle.The fuel consumption and emission of the 48 V hybrid vehicle are compared with the reference model.The simulation results show that the 48 V hybrid vehicle designed in this paper achieves the formulated economy and dynamics targets,and the emission performance is improved.The STM32 microcontroller is selected for the control strategy simulation test.The digital signal generator is used to simulate the engine and motor speed,the sliding resistor simulates the accelerator pedal and brake pedal,and the combination of LED lights and small motor rotation simulates the working state of the engine and motor.The hardware circuit and software program are designed to realize the operation of the control strategy.The test results show that the control strategy fulfills the designed function.