Research On Position Sensorless Control Of Permanent Magnet Synchronous Motor

Based on the mathematical model of permanent magnet synchronous motor,many sensorless control methods are proposed to avoid the disadvantageous influence of mechanical sensor installation on PMSM,reduce maintenance cost and improve control performance of permanent magnet synchronous motor.Sliding mode observer with strong robustness,fast convergence speed and simple structure is selected as sensorless control method for permanent magnet synchronous motor.In this paper,sensorless control of PMSM based on Super-Twisting sliding mode observer is studied.To solve the problem of chattering and rotor position observation precision when using traditional sliding mode method,two optimization schemes are designed:Super-Twisting sliding mode,sigmoid function and a phase compensation method are introduced into the control system;A method of weighting the feedback end of current loop is proposed to combine with control system.The simulation and experimental results show that the motor speed error is reduced by 45%,the motor speed variation is reduced from 11.25%to 5%,and the adjustment time is reduced by 50%.The research work is as follows:Firstly,the double closed-loop PI parameters of vector control system are adjusted by choosing i_d=0 control method and combining with the mathematic model of surface-mounted permanent magnet synchronous motor,the control system is built on Matlab/simulink to verify and analyze the selected parameters and prove the reliability of the values of the selected parameters.Secondly,Super-Twisting sliding mode and sigmoid function are introduced into the mathematical model of traditional sliding mode observer of permanent magnet synchronous motor,and an improved Super-Twisting sliding mode observer is established by adding phase compensation mechanism,the system model of weighted sliding mode observer is established and the stability is analyzed.Then,the system models of the contrast model,the improved Super-Twisting and the weighted Super-Twisting sliding mode observer are built,and the simulation experiments are carried out to analyze the optimization effects of the improved two schemes,the results show that both schemes can reduce chattering and improve the dynamic and static performance of the system.Finally,a test-bed composed of a control board,a drive board,a 100W permanent magnet synchronous motor,a 2Nm magnetic powder brake and a load control power supply with DSP as the core was constructed,the reliability of the simulation is verified by the experiments of no-load variable speed,constant speed loading and so on.