Disturbance Suppression For Linear Motor Based On Super-twisting Algorithm

Permanent magnet synchronous linear motor has been applied in many fields because of its simple structure and high reliability.But on the one hand,because of its nonlinearity and strong coupling,the traditional control strategy is difficult to achieve highperformance control effect;moreover,the permanent magnet synchronous linear motor(PMSLM)operates in the direct drive mode without the interference of gears,bearings and other transmission mechanisms,which improves the efficiency and reliability of the system and makes it vulnerable.The influence of load side thrust fluctuation.Therefore,how to suppress the disturbance and ensure the strong robustness of the system has become the key of the permanent magnet synchronous linear motor control system.In this paper,a sliding mode control system of permanent magnet synchronous linear motor(PMSLM)is constructed based on the super-helix algorithm,which includes disturbance observer.Compared with the first-order sliding mode control,the chattering suppression ability of the super-helix algorithm is verified,and the position loop control of PMSLM with high precision is realized.The research contents of this paper are as follows:Firstly,the piezoelectric current model and dynamic model of permanent magnet linear synchronous motor are deduced in this paper.According to the disturbance source of the motor,the ideal parameter motor dynamic model with concentrated disturbance is established,which is the basis of controller design and stability analysis.Secondly,the principle and design idea of the sliding mode control algorithm are introduced,and the reasons of the first-order sliding mode chattering are analyzed.The boundary layer sliding mode algorithm and the second-order superhelix sliding mode algorithm are introduced from the angle of chattering suppression.The controller is analyzed and designed based on the permanent magnet synchronous linear motor model,and the stability of the system is analyzed.The Simulink simulation model is built,and the centralized control algorithm is simulated and analyzed,which verifies the superiority of the superhelix algorithm in control accuracy and chattering suppression.Thirdly,according to the idea of super-helix algorithm and the model of permanent magnet synchronous linear motor,a super-helix sliding mode disturbance observer is proposed to observe the disturbance of linear motor system,and feed-forward compensation is used to improve the disturbance rejection ability of the system.The accuracy of the observer is verified by simulation,and the system is disturbed by positioning force and abrupt load respectively.The robustness of the system before and after using the observer compensation strategy is compared by simulation.Finally,the motor controller is built with DSP28335 chip as the core,and the experimental platform is built by connecting permanent magnet synchronous linear motor.The experiment further proves that the super-helix algorithm has higher control accuracy and lower chattering than the reaching law sliding mode and the boundary layer sliding mode.The disturbance observer is used to observe the positioning thrust rippple of the motor,and the results are in good agreement with the theoretical values.The robustness of the system is further improved by introducing the feedforward compensation strategy of the observer.