Hybrid Nonsingular Terminal Sliding Mode Control Of PMLSM Based On Disturbance Observer

Permanent Magnet Linear Synchronous Motor(PMLSM)is an evolution of the traditional rotating motor in its structure.It has the advantages of fast response,large thrust,and long life.Therefore,it has a very wide range of applications in machine tools,semiconductors,military,medical and other fields.It eliminates intermediate links such as ball screws and belts,thereby greatly improving work efficiency.In practical applications,there have been more and more occasions requiring high-precision,high-speed linear servo systems.However,in the actual operation of PMLSM,some parameter changes and external disturbances will affect the control performance of the system and reduce the system’s control performance.Therefore,it is necessary to propose a control scheme that can suppress the influence of these external factors on the entire control system and improve the control performance of the system.Therefore,this thesis combines non-singular terminal sliding mode and linear sliding mode to improve the convergence speed of the system.The exponential reaching law was improved to reduce the chattering of the system and improve the control accuracy of the system.Finally,on this basis,a disturbance observer was designed to improve the anti-disturbance of the system.Firstly,based on the relationship between linear motor and rotating motor,this thesis describes the basic structure and working principle of PMLSM,establishes the mathematical model of PMLSM in two-phase rotating coordinate system,introduces the PMLSM servo control system,and finally analyzes the external disturbance of PMLSM.Secondly,the non-singular terminal sliding mode has a fast response speed and can converge in a finite time.However,when the state point is far from the sliding mode surface,the convergence speed is slower than that of the linear sliding mode.Therefore,this thesis combines non-singular terminal sliding mode and linear sliding mode to form a hybrid non-singular terminal sliding mode strategy to improve system convergence.In the traditional exponential reaching law,when the external disturbance of the system is large,a larger switching gain is needed to suppress these disturbances,but this will cause the chattering of the system.Therefore,this thesis improves the exponential reaching law.While the system has a good dynamic response,it can also weaken chattering and improve the control accuracy of the system.Finally,although the improved exponential reaching law improves the control performance of the system,in practical applications,there are still many uncertain disturbances that affect the control performance of the system.For this reason,this thesis designs a disturbance observer to observe the external disturbances in the system,and then compensate the system through the current loop to enhance the anti-disturbance ability of the system,thereby improving the performance of the control system.In this thesis,the corresponding controller is built in Matlab/Simulink,and the simulation verification and analysis are carried out.After simulation analysis,the control strategy proposed in this thesis not only weakens the chattering of the system,improves the control accuracy of the system,and also improves the immunity of the system.