Research On Braking Strategy Of Permanent Magnet Synchronous Motor Based On Vector Control For Pure Electric Vehicle

With high energy efficiency,wide range of power sources,low noise and other significant advantages and the natural advantages in energy saving and emission reduction,the pure electric vehicle is becoming one of the important directions of the current car development.However,the driving range of the pure electric vehicle is still the bottleneck restricting its rapid development,and on the premise of limited energy storage devices,how to maximize the utilization of energy and increase the driving range of the pure electric vehicle is a main content of the present study.This paper begins with the vehicle control layer and the motor control layer and is based on the dynamic analysis of the vehicle braking process.In the vehicle control layer,the braking force is rationally distributed,which ensures that when the vehicle is responding to the driver’s braking requirements,it can take into account the braking stability and the maximum braking energy recovery;and in the motor control layer,it ensures that the motor can quickly and accurately respond to the motor braking torque command.The main research contents of this paper are as follows:(1)Review the development course and the development trend of the electric vehicle.The research contents of current motor braking process and the control method of permanent magnet synchronous motor are analyzed,and the development of semi-physical simulation technology is introduced.(2)Introduce the principle of vector control of permanent magnet synchronous motor,and propose a vector control current decoupling method for the whole region control of the motor.Based on the study of vector control,SVPWM technology is proposed and its digital realization process is analyzed.(3)Analyze the braking process of the vehicle,and use the particle swarm optimization algorithm to allocate the electric braking force and the mechanical braking force under different braking intensity and different braking initial vehicle speed,considering the drive motor constraint,the battery constraint and the regulations.Develop a braking control strategy which can take into account the braking stability and the maximum braking energy recovery.(4)Use Cruise and Matlab / Simulink joint simulation,including the establishment of the vehicle model in Cruise and the establishment of the motor model,the battery model,the motor vector control strategy model and the braking force distribution control strategy model in Simulink.According to the braking regulations,the whole model is verified by simulation experiments,and the simulation results show that the braking performance of the pure electric vehicle can meet requirements of the regulations and the braking control strategy proposed in this paper is able to recover more braking energy.(5)Establish a semi-physical simulation platform,and generate the C code with Matlab/Simulink software to directly control the motor.On the basis of simulation,the motor control strategy is further validated,and the experimental results have proved the effectiveness of the motor vector control strategy.On the premise of meeting the vehicle braking performance,the braking control strategy proposed in this paper can take into account the braking stability of the vehicle and the maximum braking energy recovery,and the proposed permanent magnet synchronous motor vector control strategy is able to quickly and accurately respond to the target speed on the semi-physical simulation platform.The research work of this paper provides a effective way to improve the energy efficiency and driving distance efficiency of the pure electric vehicle.