Research On Sensorless Control Technology Of Permanent Mag Net Synchronous Motor For Electric Welding Wire Feeder

With the national development of offshore oil,natural gas and other resources,many new technologies have been introduced into engineering construction.As the basis for the production of structural parts and the laying of pipelines,welding technology is used to improve welding quality and efficiency through continuous technological innovation.Wire feeder is one of the important components of automatic welding equipment.Usually,the wire feeder is required to have good dynamic stability and low load disturbance.Using permanent magnet synchronous motor as wire feeder motor has the advantages of large torque,small moment of inertia and high control accuracy.In order to improve the load anti-interference ability and dynamic performance of wire feeding system,and reduce the volume and peripheral circuit,the permanent magnet synchronous motor system controlled by sensorless is studied in this paper.This paper introduced the working principle and speed control range index of welding wire feeder.By using the equivalent two-phase winding model and coordinate transformation principle,the voltage equation of PMSM,the mathematical model based on complex vector and the mathematical model of rotor position estimation are derived,and the sensorless vector control and active disturbance rejection controller of permanent magnet synchronous motor are studied.In order to improve the immunity of the system and the stability of welding wire feeding,the linear active disturbance rejection control technology is adopted,and the position observer is designed through the linear expansion observer to reduce chattering and improve the accuracy of position estimation.At the same time,considering the influence of PMSM nonlinear coupling term,a dual PI sensorless control system with feedforward compensation is designed to solve the problem of uneven tracking caused by large speed fluctuation when switching speed of PI control system,It is necessary to design the controller.At the same time,considering the influence of the nonlinear coupling term of PMSM,a double PI sensorless control system with feedforward compensation is designed,which solves the problem of uneven tracking caused by large speed fluctuation when the controller is needed to switch the speed of PI control system.Therefore,the sensorless control system of PMSM based on LADRC control is designed at low speed and medium-high speed respectively,in order to improve the immunity and suppress the dynamic fluctuation during speed switching.In order to verify the correctness of the theoretical research,the simulation model is built on the platform of MATLAB/Simulink,and the simulation waveforms of the two control strategies without sensor control are compared.The simulation results shows that the designed control system has the advantages of small speed error,small rotor chattering,smooth position tracking and high estimation accuracy.In the mean time,the experimental platform of motor control system is built.By comparing the experimental waveforms of the two control strategies,the analysis shows that the LADRC control system has improved the problem of control overshoot,and the dynamic process is stable with little current distortion.