Research On Energy Management Strategy Of Four Wheels Independent Drive Series Hybrid Electric Vehicle

Hybrid car makes the drive motor and engine working in high efficiency area and economic area through a rational powertrain matching and energy management strategy.It has the advantages of low emission,high specific power and long endurance mileage of traditional internal combustion engine.At the same time,the hub motor drive vehicle has the advantages of simple structure,high transmission efficiency,independent torque control and intelligent chassis,and becomes the focus of the research of new energy vehicles.It is the development direction of the future automobile and becomes the focus research of new energy vehicles.In this thesis,a kind of Dongfeng company vehicle as the research object,under constraint conditions of improving the vehicle power demands and layout space,the four wheels independent drive hybrid power system is adopted.According to the dynamic performance index of hybrid off-road vehicle,power system selection and parameter matching calculation is carried out to determine the key parameters of power components.The CAN communication scheme and control structure of the vehicle control system are established and the distributed control mode is determined.The logic rules of On/Off control algorithm and load following control strategy are analyzed and their advantages and disadvantages are analyzed.On this basis,a compound energy management control strategy is proposed to achieve the balance between the control of the APU fuel economy and the optimal target of power battery charge and discharge efficiency.Switch four wheel drive or two wheel drive according to vehicle load condition to control the working point of the hub motors in the higher efficiency area,and improve the energy utilization efficiency of the whole vehicle.Based on the forward model,the energy management and control system structure of four wheels independent drive series hybrid electric vehicle is established.The vehicle simulation model is built on the Cruise simulation platform,and use API interface module to achieve interaction with Matlab / Simulink signal.In the Simulink environment to establish the power component controller model and the compound energy management strategy is establish in the state flow software.Through Cruise and Matlab/Simulink co-simulation,the dynamic and economic performance is simulated in NEDC cycle and UDDS cycle.The simulation results show that the energy management strategy can effectively guarantee SOC of power battery fluctuate in efficient range to avoid the power battery overcharge and over discharge status and improve the battery charge and discharge efficiency.At the same time,the engine is well controlled in the low fuel consumption area,and the fuel economy of the whole vehicle is improved.Finally,the effectiveness of the control strategy is verified by road test.The experimental data show that the acceleration time of 100 km reduced by 4.3s,and the maximum speed and maximum gradient road results have varying degrees of improvement compared to prototype vehicle,fuel consumption per hundred kilometers reduced by 29.2%.The results show that the energy management strategy can improve the fuel economy of the vehicle when the vehicle’s dynamic performance is satisfied.