Speed Control System Of Permanent Magnet Synchronous Motor And Research On Fault Diagnosis

The permanent magnet synchronous motor usually uses the position sensor(such as encoder and decoder)to obtain the real-time rotor position information to control the permanent magnet synchronous motor.However,there are some problems,such as the cost and capacity of the system and related reliability issues.Therefore,the permanent magnet synchronous motor control system with no position sensor are more and more popular.This paper studies on the speed control system of PMSM,which based on vector control,and analyzing the various components of the control system.On this basis,there is an improved PMSM speed control system to realize the control of no position sensor on entire speed range.Firstly,the paper introduces the mathematical model of permanent magnet synchronous motor and uses the vector control strategy of permanent magnet synchronous motor.The paper designs a permanent magnet synchronous motor speed control system based on vector control.It is simulated and the simulation results are obtained.Secondly,this thesis using an improved method of permanent magnet synchronous motor.The sensorless control of the whole system has realized.The sensorless control at low speed and high speed is researched for.The principle of high frequency injection and Kalman filter,the method of rotor position extraction and the control block diagram are described in detail,Each control system has been analysised in simulation and comparison for summary.Then,the paper uses the methods of high-frequency square wave injection and extended Kalman filter.Simulation results show that these two methods can obtain rotor position at low speed and medium speed with less error,lower bandwidth and more stability.Thirdly,based on the related research,it is learned that the permanent magnet motor has a higher probability of failure at high speed.Therefore,the problem of the permanent magnet synchronous motor without position sensor control at high speed has been studied.The chapter describes the type of permanent magnet synchronous motor failure,resulting in the cause of the failure,as well as a detailed analysis of the failure mechanism.Simulation results of three kinds of common faults,single-phase-to-earth,short-to-phase and permanent magnet demagnetization under the position sensorless system with extended Kalman filter show that the failure not only leads to the change of the current and other related variables and the violent fluctuation which will have an important influence on the rotor position estimation.Therefore,the detailed fault features are extracted,which verifies the importance of studying the fault of the sensorless control system.Finally,the wavelet analysis is applied to the extraction of fault features,and the diagnosis method based on wavelet base-fuzzy RBF neural network is used to improve the clustering algorithm.The experimental results show that satisfactory results can be obtained by applying the wavelet-based fuzzy RBF neural network fault diagnosis method to fault diagnosis of sensorless control system.