Permanent Magnet Synchronous Linear Motor Based On Disturbance Compensated Flux Observer Sensorless Control

Permanent magnet synchronous linear motor(PMSLM)is widely used in high-precision manufacturing and advanced industrial production because it does not use the intermediate transmission device when performing linear motion,and has the advantages of fast running speed,high control accuracy,and large thrust.In order to realize speed closed-loop control and current decoupling,the position and speed of the mover are essential in the permanent magnet synchronous linear motor vector control system platform.However,due to the high price,the installation of conventional mechanical sensors not only brings about a significant increase in cost,but also a decrease in reliability.Therefore,it is of great significance to study the sensorless control strategy.The research content of this thesis aims to achieve high-performance sensorless control of permanent magnet synchronous linear motors.First of all,based on the physical structure,operation principle and classification of different occasions of the motor,the permanent magnet synchronous linear motor models in different coordinate systems are established.Due to the end effect of permanent magnet synchronous linear motor,this thesis considers the factors of motor winding self-inductance and mutual inductance asymmetry caused by the end effect in the voltage equation and flux equation of the motor.The phenomenon of thrust fluctuation caused by asymmetry of inductance parameters is discussed,and the influence on the estimation of mover position and speed is analyzed.Secondly,the flux observer algorithm is used to estimate the position and speed of the mover of permanent magnet synchronous linear motor,and the shortcomings of conventional flux observer in linear motor are pointed out,and the sources of the limitations of conventional flux observer are explained.On the one hand,the conventional flux observer will be affected by the initial value error of flux,which will cause the distortion of flux estimation,and then lead to the reduction of the accuracy of position and speed estimation.On the other hand,due to the existence of DC component in stator current acquisition and stator voltage input,the permanent magnet synchronous linear electromotor flux will be biased during estimation,resulting in a decline in the estimation accuracy of flux,and thus the estimation accuracy of position and speed.To solve the problems mentioned above,a sensorless control method based on disturbance compensated flux observer is studied in this thesis.Notch filter is introduced in this method.Since it can filter out the fundamental frequency component in the input signal and retain the disturbance component,it can be considered as a disturbance observer.Finally,the estimated disturbance is corrected by feedback controller.The improved flux observer combined with notch filter and feedback control has the advantages of simple calculation and easy parameter debugging.It has good inhibition effect on DC bias and harmonic disturbance,makes up for the defect of conventional flux observer and does not bring the error of flux amplitude and phase.Finally,in order to verify the effectiveness of the perturbation compensation flux observer algorithm,a simulation model is established under MATLAB2018a/Simulink environment and an experimental verification platform is built with DSP TMS320F28335 as the core processor.The results of simulation analysis and experimental verification both demonstrate that the disturbance compensated flux observer can effectively reduce the estimation error of the rotor flux during the operation of the linear motor,thereby improving the estimation accuracy of the rotor position and speed.