Research On The Key Technology Of Optimization Control For 4WID Electric Vehicle Driving System

As a special driving form of electric vehicles,four wheel independently drive electric vehicles(4WID EV)omit the mechanical transmission link between each wheel,and can control the rotation speed and torque of the four wheels accurately,which can meet the driving performance and safety performance requirements that cannot be realized by many other types of vehicles.In the case of limited battery energy storage,4WID EV can improve the battery endurance by optimizing the control performance of the drive system,which is an important direction for the development of electric vehicles in the future.This paper takes the driving system of 4WID EV as the research object,and starts with the optimization of the control performance and efficiency in the three parts of acceleration slip regulation control,torque distribution and motor drive.The key technologies of optimization control in each part are studied in depth,which are as follows.(1)The dynamic model of 4WID EV on flat road and slope road is established,the coordinate transformation principle of motor is analyzed,and the motor mathematical model is established.Then,the driving control principle of 4WID EV and its optimization control problem are analyzed.(2)Based on road identification algorithm and slope identification algorithm,we design an acceleration slip regulation control algorithm which can be used in flat road and slope road.The variable gain control principle is introduced to optimize and improve the controller,and the dynamic and static characteristics of slip ratio control is better,thus effectively suppress wheel slip.(3)A torque optimization distribution strategy for 4WID EV based on optimal energy consumption was proposed.This paper constructs the optimal objective function and constraint conditions of energy consumption.Simulated annealing algorithm is introduced to solve the extremum optimization.The torque optimization distribution strategy can ensure the optimal energy consumption of the vehicle while the given torque output,that is satisfying the driver's operating consciousness.(4)A motor control strategy in full speed range is proposed.Firstly,a fast and effective MTPA control table lookup method is designed,which greatly reduces the computation of the algorithm.The variable step accumulative weak magnetic control method is designed to make the motor running smooth and stable during the entry and exit of weak magnetic control.Finally,the dynamic MTPA control is designed,which can satisfy the smooth and stable control of the motor in the full speed range.Finally,the motor test proves the effectiveness of the control method.(5)The co-simulation platform of Carsim and MATLAB /Simulink is built,the 4WID EV model,the road conditions and the simulation process are created.The vehicle control unit is developed and the hardware test platform based on d SPACE is built.The experiment verifies that the control algorithm can run stably and effectively.