Design Of Four-wheel Independent Drive Electric Vehicle Control System Based On Exterior Rotor Switched Reluctance In-wheel Motor

Driven by the in-wheel motor,the four-wheel independent drive electric vehicle is regarded as the best driving mode because of its ideal control performance.Switched reluctance motor is very suitable for electric vehicles,due to its simple structure,big starting torque and wide speed range.However,existing in-wheel motors and their improved structures lack ideal structure of reducing mechanism.In this paper,a new exterior rotor switched reluctance in-wheel motor is designed to solve this problem,and an assorted motor control system based on the whole vehicle control system is proposed.Frist,the exterior rotor switched reluctance motor is designed.The structure of the new in-wheel motor is provided,and its motion mode is analyzed.The basic parameters of the switched reluctance motor are calculated according to the dynamics of the electric vehicle,and the mathematical model of the motor is then established.The control strategy for the motor's control system is studied.Second,the vehicle controller for the four-wheel independent drive electric vehicle is built.The functions of the vehicle controller and the in-wheel motor controller are defined.The communication mode of whole vehicle is designed.The electrical system is also established.The drive strategy of the electric vehicle is studied,and the implementations of each working mode are also designed.Third,the simulation model of the exterior rotor switched reluctance motor is built in MATLAB.The 2D model of the motor is established based on Ansoft Maxwell 14.0,and the magnetization characteristic curves are obtained by the simulation.The methods for building the switched reluctance motor model are studied.The simulation model of the exterior rotor switched reluctance motor is established by fast non-linear modeling methods.The model is tested by a closed-loop speed regulating system.The simulation results show that this model accurately reflects the working characteristics performance of the motor.Finally,the Direct Torque Control system for the motor is studied by means of the mechatronics simulation method.An expression of the instantaneous torque for the exterior rotor switched reluctance motor is derived from the elementary function.Six effective voltage space vectors are selected based on the mechatronics characteristics,and the switching table is also defined.The drive system is built according to the principle of the Direct Torque Control.The simulation results indicate that the torque ripple has been efficiently controlled by the control system,suring that the In-wheel Motor can meet the requirements of electric vehicles.Meanwhile,the hardware circuit and software of the in-wheel motor controller are designed based on DSP.