Research And Realization Of Permanent Magnet Synchronous Motor Control System For Electric Vehicles

Based on the project of the Natural Science Foundation of China “Research on fault diagnosis and tolerance control of multi-phase motor drive system for electric vehicle(61603263)and the general project of Liaoning education department Province “electric vehicle research on the fault diagnosis Method of six phase permanent magnet motor Drive system(LGD2016030)”,the key technologies of permanent magnet synchronous motor drive system for electric vehicles(EV)are studied.In order to achieve high stability of the motor drive control system,permanent magnet synchronous motor vector control,maximum torque per ampere(MTPA)control and flux weakening control are studied intensively in this thesis.The protection strategies and vehicle logic control of the electric vehicle motor drive controller are analyzed deeply based on engineering practice.The main work is described in detail as follows:Interior permanent magnet synchronous motor is selected as the driving motor in this paper.Space vector pulse width modulation technology is used to realize the maximization of the voltage utilization on the premise of the limited EV battery voltage;in order to realize the minimization of stator current and achieve the optimization efficiency,MTPA control strategy is used to control the optimal combination of d-axis and q-axis component.For achieving the wide speed range of EV,the flux weakening algorithm is designed to improve the motor performance.Simulation model of the permanent magnet synchronous motor vector control system,which is based on rotor field orientation,is built by Matlab/Simulink,and system simulation results verify the effectiveness of the control algorithm.In order to overcome insufficient accuracy of detecting the rotor initial position at high speed,the symmetry method is presented to improve the accuracy of drive system by averaging the results of four absolute position measurements.Modular design concept is adopted,the protection strategies and vehicle logic control of EV controller are analyzed.From temperature fault detection and hardware fault detection,the temperature of motor,three-phase bridge and the controller,the overvoltage and under-voltage protection of bus voltage,the protection of three-phase current for fault detection and action and power-on detection of inverter circuit are studied to ensure safe and reliable operation of the system.In the vehicle control unit,the slip prevention,engage gear careless,speed-cruise and energy feedback control are designed to improve the performance of control system.In order to verify the feasibility of the control strategy proposed in this project,the permanent magnet synchronous motor drive system is built based on 32-bit high performance automobile grade micro-processing chip TriCore1782 of Infineon Company.The peak power of the system is 50 kW,peak speed is 7000 r /min and peak torque is 160 N.m.Software is studied in detail by module design idea,which is based on Tasking,the flow charts and interface function of the main sub-modules are designed.Finally,the constant speed loading experiment,initial position verification experiment and vehicle pavement experiment,which are based on the experimental platform,are carried out to verify the effectiveness of the design scheme.