Energy Management And Transient Control For Hybrid Electric Vehicle Based On Driving Cycle Identification

Hybrid electric vehicle equips with the motor drive system on the basis of traditional fuel vehicle,it is the key to achieve energy saving and emissions reduction with the coordination between engine and motor.The control problem of HEV mainly includes the steady state energy management and the transient process control,and how to solve such key technical problems is of great practical significance for further promoting the industrialization and utility of HEV.A steady state energy management strategy based on driving cycle identification and a coordinated control strategy for transient mode switching process based on a type of parallel hybrid electric vehicle are proposed in this paper.The major contributions are developed as follows:Firstly,the structure of PHEV powertrain system is analyzed,and the model of power and transmission system is established.The principle of logic threshold value control strategy is described,to overcome the defect of relying on expert's experiences,the particle swarm optimization algorithm is used to optimize the parameters of the control strategy and the powertrain parameters.The objective function of the minimum fuel consumption of the engine and the ISG motor is taken as the objective function.PHEV dynamic performance and fuel economy simulation are carried out to verify the correctness of built models and parameter optimization,and simulation results show that the optimized PHEV vehicle performance is improved.Above works lay the foundation for the study of PHEV steady state energy management and transient process control.Secondly,in order to solve the problem that the logic threshold value control strategy is easily affected by the driving cycle and further improve the fuel economy of PHEV,aiming at the influence of driving cycle on the vehicle fuel economy,an energy management method based on driving cycle identification is proposed.Combined driving cycle is constructed with 30 standard driving cycles from ADVISOR software,and average speed,mean absolute acceleration and idle time ratio are selected as the eigenvalue.Combined with the K-means++ clustering algorithm,clustering results of four typical driving cycles corresponding to congestion,urban,suburban and high-speed are obtained by clustering the combined driving cycles.The mathematical model of the vehicle fuel consumption and energy consumption is built,the optimal engine and the ISG motor power distribution under four typical driving cycles is solved based on the Pontryagin minimum principle.A vehicle simulation model is established based on the MATLAB/Simulink platform,and simulation results of a random driving cycle show that the control system can accurately identify the driving cycle,and energy distribution between engine and motor is improved.Finally,two typical processes of motor drive mode switches to combined drive mode and motor drive mode switches to engine drive mode are analyzed on the basis of the steady state energy management strategy based on driving cycle identification,the mode switching dynamic equations are established,and the cause of torque jerk during mode switching process is studied.The multi-agent control theory is introduced into the PHEV operating mode switch,the system Agent,engine Agent,motor Agent,and clutch Agent are defined respectively according to the dynamic and transmission system structure of PHEV,and a transient process coordinated control strategy based on MA is proposed.A multi-agent coordinated control method for PHEV torque and speed during the stage of engine starting,speed regulation and motor torque compensation is proposed,Agents take the minimum torque jerk as the goal to reduce the torque and speed fluctuation during mode switching process.The control effect simulation of the mode switching process under and without MA coordination is carried out,the results show that the vehicle torque jerk under two typical mode switching process is reduced from 19 m·s-3 to 6.5 m·s-3 and 25m·s-3 to 3.7 m·s-3 respectively,the vehicle driving performance and mode switching smoothness is promoted,and the validity of proposed control method for PHEV transient process control is verified.