Research On Economical Speed Planning And Energy Management Of Intelligent PHEV Considering Ramp Information

With the increasingly severe problems of environmental protection and energy crisis,and the increasingly strict energy consumption and emission regulations,the global automobile industry has set off a wave of development from traditional fuel vehicles to new energy vehicles.Plug-in Hybrid Electric Vehicle(PHEV),as a transition product from traditional fuel vehicles to pure electric vehicles,has the advantages of both fuel vehicles and pure electric vehicles,and has broad development prospects.This paper takes the intelligent PHEV as the research object,aiming at the problem of high energy consumption of the vehicle on the slope,and focuses on the economical driving control method of the intelligent PHEV on the slope,so as to improve the energy consumption economy of the PHEV vehicle on the slope.(1)Analyze the configuration characteristics and working mode of PHEV,build the key model of the vehicle power system,formulate the rule-based CD-CS energy management control strategy,simulate the combined working conditions of WLTC,and analyze the effectiveness and rationality of the vehicle model and energy management strategy.(2)Aiming at the problem of poor energy consumption economy of vehicles driving under ramp conditions,a hierarchical control strategy for intelligent vehicles based on trapezoidal speed planning algorithm and CD-CS energy management strategy is proposed.The basic idea of the intelligent car hierarchical control strategy is to plan the speed of the vehicle in the real road conditions through the trapezoidal speed planning algorithm in the upper controller,and then combine the road slope information input to the underlying controller to distribute energy with cd-CS strategy,thereby guiding the economic driving of the vehicle.Simulation results show that under the hierarchical control strategy,the vehicle takes 936.6s to pass through the simulated road section,consumes 0.6135 L of fuel,and the power battery SOC decreases by 0.1907.(3)Aiming at the problem that the speed planning and energy management are not synchronized in the hierarchical control strategy,resulting in the distribution of some working points of the power source in the inefficient range,a global economic vehicle speed planning algorithm based on dynamic planning is proposed.A multi-objective optimization problem that considers the coordinated optimization of travel time and driving energy consumption is constructed,and an economical ramp speed planning algorithm based on dynamic planning method is designed.Simulation results show that the global economic vehicle speed planning algorithm based on dynamic programming under the same conditions reduces fuel consumption by 8.29% and reduces power consumption by 26.06% compared with hierarchical control strategy,but the travel time increases by 94.96%.(4)Aiming at the problem that the global optimization algorithm has a large amount of computation and cannot optimize in real time,an instantaneous economic vehicle speed control strategy considering energy conversion is proposed.Summarizing the trend of global optimal economic speed,the equivalent conversion factors of body kinetic energy,battery power and fuel are designed respectively.Based on the information of road gradient,driving speed and battery SOC status,the equivalent conversion factor of kinetic energy and the equivalent conversion factor of electrical energy are analyzed and calculated,and the engine torque,drive motor torque and transmission speed ratio with the minimum equivalent energy consumption are solved.Simulation results show that compared with the hierarchical control strategy,the fuel consumption is reduced by 4.12%,and the stroke time is reduced by 34.52%compared with the global economic speed planning algorithm,and the amount of computation is reduced,which can realize the real-time online optimization of the on-board microprocessor.In addition,the instantaneous speed control strategy in the car follow-up scenario is designed,and the variable front-end time distance strategy is used to ensure the driving safety of the vehicle when following the car.Simulation results show that the instantaneous speed control strategy in the follow-up scenario can effectively ensure the safety of vehicle follow-up,and improve the energy economy of vehicle driving.