Robustness Analysis And Improvement Of Asynchronous Motor Drive System Under Field-Weakening Region

Asynchronous motor has the advantages of simple structure,convenient manufacturing,low price,reliable operation and suitable for harsh conditions,so asynchronous motor is widely used in industrial electric vehicle drive system.Because the inverse ratio magnetic weakening scheme is simple,effective and easy to implement,it is widely used in the asynchronous motor drive system of industrial vehicles.However,the operation conditions of industrial vehicles are harsh and complex.In the traditional industrial asynchronous motor drive system,when the motor parameters have errors,it is easy to lose control in the high speed stage.Therefore,this paper studies this problem,aiming at improving the robustness of the industrial asynchronous motor drive system in the high speed region.(1)In this paper,the rotor flux observation technology is studied deeply,and the reason why the high speed stage control system is easy to lose control when encountering large load disturbance is explained.The analysis shows that when the flux orientation error exists,too much torque current will cause the system to lose control.The motor parameter error is an important factor affecting the flux observation accuracy.Therefore,this paper analyzes the influence of different torque current and excitation current on rotor flux observer under the condition of motor parameter error in high speed stage.On this basis,the influence of the parameter error on the torque output capacity of the traditional vector control system with inverse rotation speed and rotor flux orientation is analyzed..(2)In order to improve the robustness of industrial vehicle induction motor at high speed,a coordinated control scheme of torque current and rotor flux is designed in this paper.The amplitude of torque current is limited according to the difference between the reference rotor flux and the observed rotor flux.This scheme is simple and effective,and does not need to add additional controller.When the system encounters a large load disturbance,the rapid growth of torque current can be restricted in time,so as to avoid the system out of control,and improve the robustness of the motor control system.(3)An experimental platform based on TI DSP chip TMS320F28335 was built to complete the hardware and software implementation of asynchronous motor speed regulation system,and the correctness and effectiveness of the proposed coordinated control method of torque current and rotor flux were verified experimentally on the platform.There are 50 figures,1 table,and 78 citations in this thesis.