Research On Energy Control Strategy Of All Time Four Drive Hybrid Electric Vehicle

Under the condition of deteriorating environment,decreasing oil resources and increasing demands for human living environment,the hybrid electric vehicle has become the trend of development both at home and abroad due to the limitation of battery capacity.The four wheel drive hybrid electric vehicle has attracted more and more attention because of its good handing and stability.But multiple power sources need to work together to increase the difficulty of development.The design and Simulation of multi power source control strategy is the core and foundation of vehicle controller.As a key technology of hybrid electric vehicle,energy management is of great significance for improving the performance of hybrid electric vehicle.This paper aims at the research object of all time four drive hybrid electric vehicle,The main research contents are as follows:(1)The front and rear driving structure of the full time four drive hybrid electric vehicle is determined,and the selection of the power components and the matching of the parameters are made according to the requirements of the vehicle parameters and performance indexes.(2)Taking the minimum fuel consumption as a goal,a rule-based logic threshold energy control strategy is designed.The steady working mode energy flow is analyzed,and the vehicle requirement torque is obtained by analyzing driver's intention.According to vehicle status information,engine start stop control,operation mode switching control and energy distribution control of multiple power sources are designed,and a corresponding control strategy model was built based on Matlab/Simulink.(3)In order to further increase the rationality of torque distribution,the principle of fuzzy control system is designed.A fuzzy controller was developed with power battery SOC and the ratio of vehicle demand and optimal engine torque torque as the input,the engine torque coefficient for work output.And the input-output variable was fuzzed and the fuzzy subset and fuzzy control rule were set up.Finally,a fuzzy control strategy model for real-time optimization of engine target torque was built.(4)Based on the Cruise platform,the vehicle model was built,combined with the control strategy model built in Matlab/Simulink,and the joint simulation is carried out under NEDC condition.The simulation results of energy management strategy based on the logic threshold control and fuzzy optimal control were compared and analyzed.The simulation results show that the designed control strategy meets the dynamic driving demand and realizes the smooth switching of the working mode.Compared with the logic threshold control strategy,the energy management strategy with fuzzy optimization is better,and the fuel economy of the vehicle is further improved.