Research On Control Strategy Of Automobile In-wheel Motor

The electric vehicle driven by in-wheel motors has the advantages of compact chassis,high energy transfer efficiency and large space.Electric wheel integrates the motor and the reducer into the rim of the wheel.The characteristic of each wheel independently controllable provides a great degree of freedom for the dynamic motion control of the vehicle.Driven by in-wheel motors is a promising direction and research hotspot in the development of Electric Vehicle(EV)power system.In-wheel motor is the core component of the in-wheel motor EV.Research on the control of in-wheel motor helps to solve the problems of heat dissipation,driving stability and riding comfort of the in-wheel motor EV,and has far-reaching practical significance for improving the performance of the vehicle.In this paper,the MATLAB/Simulink simulation and experimental verification methods are used to analyze the control strategy of in-wheel motor.Firstly,the reason for the large amplitude of torque ripple in the traditional Direct Torque Control(DTC)of the hub permanent magnet synchronous motor is analyzed.Considering the two factors of the switching frequency of the inverter and controller type of DTC,combining with Space Vector Pulse Width Modulation(SVPWM),two control strategies are designed by fuzzy theory and Super-twisting two order sliding mode algorithm,which are FL-SVPWM-DTC(Fuzzy Logic SVPWM DTC)and ST-SVPWM-DTC(Super-twisting SVPWM DTC).The control characteristics of the two strategies are compared and analyzed by simulation with MATLAB/Simulink.The simulation results show that both FL-SVPWM-DTC and ST-SVPWM-DTC can effectively restrain the torque ripple and system overshoot,shorten the response time of the system and regain the steady state and the setting time of the system,improve the control precision and the response speed of the system.And the performance of the FL-SVPWM-DTC is better than the ST-SVPWM-DTC in suppressing system overshoot and torque ripple,while the ST-SVPWM-DTC dynamic response speed and load-resisting capability of ST-SVPWM-DTC is superior to FL-SVPWM-DTC.Secondly,the driver of the motor drive experiment box is redeveloped through cSPACE and MATLAB/Simulink.On this platform,a rapid prototype experiment is carried out to verify the effectiveness of FL-SVPWM-DTC and ST-SVPWM-DTC in improving the performance of traditional DTC.Finally,a Simulink model of the speed type electronic differential control strategy is built.The two control strategies are applied to the electronic differential system,and the influence of the motor control characteristics on the motion characteristics of the electric wheel is analyzed.The simulation results show that the response speed of the motor torque affects the track of the vehicle,and the control precision of the motor affects the stability of the vehicle.The vehicle stability is better when the FL-SVPWM-DTC strategy is adopted.When the ST-SVPWM-DTC strategy is adopted,the actual running track of the vehicle is closer to the ideal trajectory,which is more suitable for the in-wheel motor differential control.