Sensorless Control Of Permanent Magnet Synchronous Linear Motor Based On Improved Flux Observer

In high-precision industrial fields,permanent magnet synchronous linear motor(PMSLM)as the core device of the direct drive system is widely used,such as rail traffic and semiconductor manufacturing,because of its high accuracy,fast dynamic response,large thrust and other advantages,and it can realize linear drive directly without intermediate conversion device.The traditional mechanical sensors increase the cost of the system and restrict the use environment of PMSLM.Therefore,obtaining accurate speed and position information is very essential to achieve high precision control of PMSLM by sensorless control methods.Firstly,the surface PMSLM as the controlled object,the mechanical structure and working principle of PMSLM are explained,the mathematical modeling is established through different coordinate systems,the internal thrust ripple of PMSLM is introduced based on the mathematical model of the motor,the mathematical model based on mismatch factors is established,the vector control principle of vector control and the space vector pulse width modulation technology are introduced.Secondly,in combination with the characteristics of the controlled object,the reasons for selecting of flux observer is explained by illustrating difficult reasons for PMSLM to achieve sensorless control,the method of obtaining speed information by the flux linkage observer is discussed.Aiming at the inaccurate flux estimation and the inability to obtain accurate speed and position information of the traditional flux linkage observer under the influence of the thrust fluctuation caused by the end effect and so on,an improved flux linkage observer is studied.The improved flux linkage observer obtains current error information through mathematical changes in the observed flux linkage,and feed-forward compensation of the current error information,flux linkage observer model with flux linkage compensation is designed,which effectively weakened the influence of internal disturbance such as thrust fluctuation on the accuracy of the flux observer,and its stability is analyzed.Finally,the sensorless control of PMSLM based on the improved flux linkage observer is simulated and verified by building model,and an experimental platform based on the TMS320F28335 chip as the core controller is built,the information of speed and position are carried out on this experimental platform.The experimental results show that the senseless control method of PMSLM based on the improved flux observer can weaken the influence of thrust fluctuation on the accuracy of the observer,improve its speed estimation accuracy and tracking ability,and ensure the precise operation of the motor control system.