Research On MRAS Estimator For Speed Sensorless Vector Control Of Traction Motor

With the rapid growth of national economy and the improvement of people's living standards,the demand for railway and unban rail transit is gradually expanding.As the core of locomotive vehicle,electric traction drive and its control system take on the responsibility of providing traction power for locomotive vehicle.The control performance directly determines whether the operation of the locomotive is normal.When vector control is adopted to the electric traction drive system,the speed information is requisite.In order to solve the problems of reliability degradation,maintenance headaches,system complexity and costs increased caused by speed sensor,speed sensorless control technology has become a hotspot in recent years.In this paper,a certain type of subway vehicle's traction induction motor is taken as the research objective,and the speed sensorless vector control technology is studied,which has certain theoretical and engineering significance.Firstly,the mathematical models of induction motor in different coordinates are briefly introduced.Based on this,this paper gives introduction of the indirect rotor field oriented control method which is used to meet the control performance of rapid torque response and wide speed range for traction motor.Secondly,after considering the accuracy of the identification speed,the amount of control algorithm,the stability and other factors,the model reference adaptive system(MRAS)is selected to identify the speed in this paper.Through the research of traditional rotor flux MRAS,the problems of the DC offset and error accumulation caused by the pure integral in the voltage model(reference model)are solved by using the first-order low-pass filter and the compensation signal to replace the pure integral to improve the voltage model.The stator current MRAS is researched to avoid the error caused by the inaccuracy of reference model.Then,based on the improved rotor flux MRAS speed sensorless vector control method and the stator current MRAS speed sensorless vector control method,the simulation models are built and simulated in Matlab/Simulink.According to the simulation results,the influences of motor parameters on the system are analyzed and control performance of the two control algorithms are compared to verify their correctness.Finally,the hardware-in-loop experiment platform based on SpaceR real-time simulator and TMS320F2835 DSP controller is established.The controlled object model and control program are completed and the related experiments are also finished on the experimental platform.The experimental results verify that the designed speed sensorless vector control algorithm based on MRAS in this paper is correct and feasible.