Control System Optimization Of Permanent Magnet Synchronous Motor For Urban Rail Train

The Interior Permanent Magnet Synchronous Motor(IPMSM),which are more and more used as traction motor in urban rail transit that have many advantages,such as small size,high efficiency and less maintenance.The distance between the station and station of urban rail transit is short and the traffic density is high.In the process of frequent switching of urban rail transit vehicles under start-up,acceleration,uniform driving and braking conditions,the traction motor of urban rail trains has problems such as overshoot of speed,long time of stabilization to reference speed,chattering of traditional Sliding Mode Observer(SMO)and deviation of rotor position estimation.This will not only affect the service life of the motor,waste resources,but also reduce the efficiency in the long run.In order to reduce the speed overshoot,save energy and improve efficiency,the optimization of the control system of IPMSM for urban rail trainsit is studied.Firstly,the mathematical model of IPMSM for urban rail transit is established,and the relationship between voltage,current and electromagnetic torque is analyzed.The control strategy of Maximum Torque Per Ampere(MTPA)is adopted in low-speed section,and flux-weakening is used in middle and high speed section to increase the adjusting range of speed.Secondly,aiming at the problems of speed overshoot and long time to reference speed in vector control algorithm of IPMSM based on rotor field orientation for urban rail trains,the parameters of Proportional Integral(PI)Controller are optimized by random search algorithm.The results show that the speed overshoot is decreased,the response of the speed is improved,and the time to stabilize to reference speed is greatly shortened.Because of the range of adjustable speed of IPMSM is relatively small,the flux-weakening control is realized by compensating the excitation current,which increased the range of speed regulation.Then,aiming at the shortcomings of traditional SMO,such as chattering and deviation of rotor position estimation,a new SMO of IPMSM is established in two-phase rotating coordinate system.Saturation function is selected as the switching function,and Phase-Locked Loop(PLL)technology is used to estimate the information of rotor position and speed.The validity of sensor less control of IPMSM for urban rail train is verified by MATLAB/Simulink.Finally,using the IPMSM as the test motor,the DSP TMS320F28035 chip produced by TI company as the main control chip,and C language as the control software programming language.Through the analysis of the experimental waveform,the rationality of the optimization algorithm is verified.