Research And Development Of Drive Motor Control System For Pure Electric Vehicle

The development of new energy electric vehicle is an important solution to solve the problem of energy crisis and environmental pollution.In recent years,pure electric vehicle has been developing rapidly due to their high energy efficiency,zero emissions,and simple structure.Drive motor is the only power source for pure electric vehicle,the merits and reliability of motor control performance determine the driving and safety of the vehicle.So the motor control system as the core technology of pure electric vehicle,has become a hot academic research.In this thesis,the inner permanent magnet synchronous motor is taken as the research object,and the drive motor control system of the pure electric vehicle is developed and studied.First of all,this thesis introduces the mathematical model of the permanent magnet synchronous motor and its vector control theory.The vector control method based on coordinate transformation has realized the simplification of the mathematical model of the motor,which makes the permanent magnet synchronous motor as the AC motor has the same speed characteristics as direct and convenient with the DC motor,and lays the foundation for the further drive motor’s high performance control.Secondly,according to the different driving requirements of the constant torque area and constant power area,the maximum torque current ratio control strategy is adopted under the base speed of the driving motor,and the project is approximately realized,and the weak magnetic control strategy of voltage feedback is adopted above the base speed.The simulation results in the MATLAB/Simulink environment show that the maximum torque current ratio control can make full use of the torque of the built-in permanent magnet synchronous motor,reduce the loss,and the weak magnetic strategy control of the voltage feedback method is simple,can effectively improve the speed range of the motor as well.Thirdly,based on the high dependence of vector control on the speed signal,the sliding mode variable structure control method is used to estimate the speed to realize sensorless control of the motor,and an improved method of replacing the traditional symbol function with the sigmoid function is proposed,thus optimize the sliding mode variable structure control.The simulation results in the MATLAB/Simulink environment show that the speed of the sliding mode variable control method can effectively track the actual speed change of the system,and the proposed function replacement method effectively alleviates the inherent buffeting problem of the system.Finally,the prototype of the drive motor controller is developed.The hardware of the controller is designed in a modular way.The hardware circuit is divided into two parts: the main control board and the driver board.The hardware design is based on the TMS320F28035 DSP chip.The main control circuit is made into a PCB board and tested.The experiment has preliminarily verified the correctness of the hardware design.This thesis analyzes and studies the control strategy for the the drive motor of a pure electric vehicle and develops a prototype of the controller.The simulation method and the experimental method are used to verify the control strategy and the hardware circuit.It has theoretical guidance and engineering application value for the development of pure electric vehicle drive motor control system.