Study On Control Strategy Of Permanent Magnet Linear Synchronous Motor Based On Internal And External Disturbance Suppression

Computer numerical control(CNC)machining technology is an important part of the development of modern industry,and the embodiment of national comprehensive industrial strength.As a representative of high-efficiency linear motion and high-precision actuator,permanent magnet linear synchronous motor(PMLSM)has gradually become a hot spot in the field of numerical control and industrial control servo.However,as the PMLSM system lacks the buffer of the intermediate transmission mechanism,the internal and external disturbances of the system will directly affect the motor itself.The internal and external disturbance suppression is the key to achieve the high-precision and high-dynamic control of the PMLSM system,and it is also one of the research hotspots of the system.Based on the plate PMLSM,the traditional mathematical model of the PMLSM system is derived.Then,considering the coupling effect between the d-q axis of the PMLSM system,a more accurate mathematical model of the system is established.Furthermore,based on the accurate mathematical model,the characteristics of the friction,detent force and current harmonic disturbance are analyzed.And the investigations on the suppressions of the internal and external disturbances are carried out.For the external disturbance of the system,the speed dead zone of the PMLSM under the influence of friction is analyzed.The Lu Gre friction model of the system is identified by genetic algorithm,and the transitional state friction model is modified by the Fourier series fitting method.Then the friction of the system is compensated by the compound control method of feedforward control and feedback control.For the internal disturbance of the system,the disturbance characteristics of detent force and current harmonic are analyzed.The balance relations of the detent force,electromagnetic force and friction force of PMLSM during the pre-positioning are mainly analyzed.Considering the movement direction of the PMLSM during the pre-positioning,the dichotomy method is used to estimate the final position of the motor pre-positioning iteratively.The method can reduce the impact of the detent force on the initial position estimation of the motor.Based on the analysis of the current harmonic characteristics of the PMLSM system,the control strategy of double current loop(Proportional Resonant current loop and harmonic compensation current loop)is adopted to suppress the main harmonic of the PMLSM system.At last,a drive controller platform which employs the chips of ARM and FPGA is designed and manufactured for the PMLSM.The experimental research on friction suppression,pre-positioning algorithm verification and harmonic current suppression of the PMLSM system is carried out.The simulation and experimental results show that the disturbance suppression algorithm used in this paper has an obvious inhibition effect on the internal and external disturbances of the PMLSM system.