Sensorless Control Of PMSLM Based On PLL Adaptive Sliding Mode Observer

With the expansion of modern manufacturing scale,the requirement of manufacturing level has been gradually raised,so high-end CNC machine tools and other manufacturing equipment is more indispensable.Permanent Magnet Synchronous Linear Motor(PMSLM)is extensively applied in CNC machine tools with high velocity,high efficacy,high accuracy,rapid response,and no intermediate transmission linkages compared to traditional rotary motors.In the control system of PMSLM,the position and speed of motor are typical obtained by hardware sensor,such as encoder and Hall sensor,etc.However,there are many problems in hardware sensor,such as high cost,low reliability and high environmental requirements.Therefore,the sensorless control strategy for PMSLM has received much attention from relevant experts and scholars.In this paper,a sensorless control strategy is proposed to improve sliding mode observer for PMSLM operating at medium and high velocity.The main research contents are as follows.Firstly,this paper analyzes the basic structure and working principle of PMSLM.And inferred about the transformation principle of ABC natural coordinate system,αβstatic coordinate system and dq rotating coordinate system,also the mathematical model under three coordinate systems is established,and the Space Vector Pulse Width Modulation(SVPWM)is thoroughly described.Secondly,the essential concept of vector control and the interrelated realization method are expounded.Based on the vector control system of i_d=0,the two closed-loop speed control system and the three closed-loop servo control system of PMSLM are constructed by MATLAB/Simulink,complete the simulation experiment,and provides the basis for the realization of the subsequent sensorless control method.Then,based on the traditional sliding mode observer,an improved sensorless control method is proposed.Based on Lyapunov stability theorem,the adaptive law of back-EMF is obtained,the adaptive sliding mode observer is constructed,and the traditional arctangent function is replaced by the phase-locked loop structure.The position and speed information of the PMSLM mover is obtained,which further weakens the chattering of the system,improves the accuracy of the control,and establish the model with simulation in MATLAB/Simulink,which verifies the superiority of the proposed algorithm.Finally,the physical experiment platform of PMSLM is built and verified,and the hardware part and software design of the platform are discussed.The program flow chart of vector control and sensorless control algorithm is designed,and the vector control algorithm of PMSLM is experimentally validated and analyzed on the experimental platform,which verified the feasibility of this control method in practical application.