The Research Of Current Harmonic Suppression For Permanent Magnet Synchronous Linear Motor Based On Resonant Two Degree Of Freedom Algorithm

In order to achieve the linear feed movement,Permanent magnet synchronous linear motor(PMSLM)without core is gradually replacing the traditional linear implementation way of PMSM combining with the roller screw,synchronous belt because of its large thrust,large travel and high acceleration,high positioning accuracy,etc,which is commonly used in the field of high precision machine tools.Precision is an important performance metrics of measuring the laser engraving machine,3D printers and other machine tool processing efficiency and quality.In a PMSLM control system,the current loop is the inner ring,and the current quality determines the thrust of reliability and the NC machine tool location accuracy.The more current harmonic components,the bigger thrust fluctuation,the worse system operation stability,the worse location accuracy.Therefore,this paper proposed a resonant two degree of freedom PID control algorithm which suppresses the PMSLM harmonic current.The research is focused on the following aspects:1.Regarding the PMSLM position,speed and current closed-loop vector control system,First of all,the PMSLM mathematical models are deduced in the three coordinate systems,respectively.Then,the SVPWM technique is expounded and simulated and this paper realizes initial position detection by the magnetic positioning method to make sure PMSLM control system normal boot.Finally,this paper expounds the basic principle of vector control and set the PMSLM vector controlsystem model based on Id*=0 control method,which is the research foundation of below further study of current harmonic suppression simulation and experimental verification.2.Affected by the nonlinear factors such as the inverter dead time effect,etc,PMSLM phase current contains some harmonic,which generates thrust fluctuation.So,in order to suppress the harmonic,firstly this paper analyzed the PMSLM current harmonic components.Secondly,the resonant controller widely applied in the grid-connected system is introduced into the current PID controller.This paper uses resonant controller's high gain characteristic to implement the current harmonic suppression and realize perfect input signal tracking analyzes.Thirdly,this paper adopts two degree of freedom(2DOF)algorithm to solve the overshoot response which is produced by the resonant controller.Finally,combining with resonant controller,2DOF algorithm,this paper proposes a resonant-2DOF algorithm,and designed resonant-2DOF PID controller.Simulation results show that the resonant-2DOF PID control algorithm is correct and effective.3.In order to optimize the resonant-2DOF PID controller parameters,this paper adopts the differential evolution(DE)algorithm.First,this paper expounds the principle of DE algorithm;Then,on this basis,sets up the parameter setting simulation model based on DE algorithm,the simulation result is a set of optimal PID control parameters K_p?K_i?K_d combination;Finally,this paper sets up current harmonic suppression simulation model based on resonant-2DOF PID control algorithm,and makes the optimal parameter combination got by DE algorithm substitute into resonant-2DOF PID controller and traditional PID controller to make the contrast simulation experiment compared with the traditional PID control algorithm.4.This paper sets up the PMSLM control system experiment hardware control platform;then makes experimental verification under the different load and velocity conditions based on the real-time simulation control system AD5435.At last,the simulation results and experimental verification results both demonstrate that the resonant-2DOF PID control algorithm can suppress current harmonic,weakens the thrust fluctuation,which is of great significance of improving the positioning precision of the linear servo control system.