Study On Electronic Differential Control Of In-wheel Motor Electric Vehicle

The electric vehicle with the advantage of no pollution, low energy consumption, has been highly valued in recent years. The structure of in-wheel motor electric vehicle is relatively simple, and it has high transmission efficiency, achieve the goal of the vehicle lightweight, it is widely concerned. Electronic differential control of in-wheel motor electric vehicle is designed to replace the traditional mechanical differential for the purpose, to achieve the drive motor coordinated control as the goal, so as to ensure the running stability of the vehicle steering driving, it is one of the key technologies to be solved. So this paper made a further study on the electronic differential control of in-wheel electric vehicle. The main research contents of this paper are as follows:(1) Firstly, according to parameters of the vehicle model, based on CarSim software and MATLAB/Simulink software established a in-wheel motor electric vehicle simulation model that can reflect the running state of a vehicle, and to simulation analysis and verify on the electric vehicle model, the research of in-wheel motor electric vehicle simulation model laid the basis for the study of electronic differential control.(2) Electronic differential control in order to achieve the purpose of control, which need for accurate measurement of vehicle motion state. But actual motion state of the vehicle such as speed, while it is possible to use some special equipment to measure but the cost is higher, some state variables such as the sideslip angle, even can not be measured. The application of Calman filtering theory, the paper carried out on the vehicle state estimation, and the estimation algorithm is verified through typical experimental condition in the CarSim software.(3) The in-wheel hub motor electric vehicle in steering, the left and right sides of the driving wheels passing different trajectories in the same time, due to the drive wheels can be independent controlled. Therefore, it is necessary to design a control to achieve differential control of left and right sides of the wheel, this control is known for the electronic differential control. In order to achieve differential control, the steering kinematics reference model is established, establish the model of electronic differential control simulation model in MATLAB/Simulink software based on the kinematics reference model. Determine the electronic differential of speed torque control algorithm, design the drive torque divider, through CarSim and MATLAB/Simulink co-simulation, by controlling the driving wheel drive torque to achieve actual wheel speed tracking reference wheel speed, through on the driving wheel drive moment redistribution control, to achieve differential and differential drive torque control thought.(4) In order to verify the design of electronic differential speed control algorithm is effective, control algorithm is verified through the first choice of open and closed loop experimental in CarSim software. In order to further illustrate the effectiveness of the electronic differential control algorithm, select typical experiment conditions in driving simulator hardware in loop test bench to verify it again. And from the vehicle drive control, handling stability, driving safety etc. angle of electronic differential speed control for objective evaluation. The results show that the design of the electronic differential control strategy can realize the in-wheel motor electric vehicle differential performance when steering.