Research On Thrust Fluctuation Suppression And Speed Control Of Permanent Magnet Linear Synchronous Motor

Permanent magnet linear synchronous motor has the characteristic of not requiring intermediate mechanical transmission parts,which makes it has the advantages of precise control,fast response speed,high efficiency and high thrust strength.It has been widely used in precision CNC machine tools,high precision industrial servo control systems and other fields.However,the electromagnetic thrust fluctuations caused by internal mismatch disturbances such as cogging force disturbances and external load mismatch disturbances such as load force disturbances in the permanent magnet linear synchronous motor directly act on the PMLSM secondary.It reduces the system anti-interference performance,speed tracking accuracy and increase the speed fluctuation.In order to suppress the thrust fluctuations and speed fluctuation of the system,based on the designed mismatched disturbance observer,a second-order non-singular terminal sliding mode controller,a second-order fractional-order non-singular fast terminal sliding mode controller,a complementary controller based on optimal control and sliding mode control are designed.Based on simulation experiments,the effectiveness of the designed control strategy is verified.Firstly,the basic structure and working principle of permanent magnet linear synchronous motor are introduced.Based on the vector control theory and the stator current control method,a mathematical model of PMLSM is established.Targeted analysis of internal mismatch disturbances such as friction disturbances,end effect disturbances,cogging force disturbances,ripple thrust disturbances existing in the PMLSM system,a mathematical model of disturbances is established.Based on the mismatched disturbance model,a PMLSM mathematical model with complex disturbance model is established.Secondly,a second-order non-singular terminal sliding mode speed controller based on the designed mismatched disturbance observer is proposed to suppress the thrust fluctuation of the system.A mismatched disturbance observer based on the backstep sliding mode surface is proposed to estimate the mismatched disturbance of the system.The integration of the disturbance observation value and the integration of the cross-axis feedback current are introduced into the speed controller.At the same time,a second-order non-singular terminal sliding mode controller is designed by combining the non-singular terminal sliding mode surface with finite time convergence characteristics.The single controller completes the speed control of the permanent magnet linear synchronous motor.The effectiveness of the designed mismatched disturbance observer and controller is verified through simulation.Furthermore,a second-order fractional-order non-singular fast terminal sliding mode controller with self-tuning parameters is proposed.The mismatched disturbance estimation value is obtained through the designed mismatched disturbance observer based on the backstepping sliding mode surface.Taking the velocity error and the cross-axis feedback current as state quantities and introducing mismatched disturbance estimation,a new first-order sliding mode surface is designed.At the same time,in order to reduce the jitter amplitude of the sliding mode surface,a second-order controller is designed based on the non-singular fast terminal sliding mode surface.The integer order differential terms in the non-singular fast terminal sliding mode surface are replaced with fractional order differential terms.In order to further improve the system convergence speed and PLMSM steady-state accuracy,the fuzzy adaptive tuning is performed on the fractional order based on fuzzy theory.The effectiveness of the designed controller and parameter fuzzy tuner is verified by simulation.Finally,a complementary controller based on optimal control and sliding mode control is proposed.The permanent magnet linear synchronous motor system is divided into a known part and a mismatched disturbance part.For the known part of the system,the optimal controller is designed based on the control Lyapunov function theory.Aiming at the part of mismatched disturbance,the disturbance observer is used for observation.Based on the mismatched disturbance observation value,a first-order sliding mode controller is designed.On this basis,combined with the finite time convergence of the non-singular fast terminal sliding mode surface,the design of high-order sliding mode control.Simulation results show that the two designed control strategies have better anti-interference and robustness.