Sensorless Control Of Permanent Magnet Synchronous Motor Based On Quasi-PR Observer

In recent years,permanent magnet synchronous motor(PMSM)has been widely used.In traditional permanent magnet synchronous motor(PMSM)control system,position sensors are used to obtain rotor position and speed information.However,the installation of position sensor reduces the robustness of motor control system.This paper designs a set of control schemes for sensorless control of permanent magnet synchronous motor in full speed range,including I/F startup,sensorless control based on sliding mode observer,weight-based switching method,and proposes a new quasi-PR observer method for high-speed operation of permanent magnet synchronous motor.The classical sensorless control method based on SMO(Sliding Mode Observer)observer is adopted for middle and high speed range of permanent magnet synchronous motor.Firstly,the mathematical model of SMO observer is introduced.Secondly,the asymptotic stability of sliding mode observer is discussed by using Lyapunov theorem.Thirdly,in order to weaken the chattering problem,the saturation function is used instead of the sign function.Finally,the performance of the sliding mode observer is verified by simulation and experiment.To avoid chattering,a position observer based on quasi PR control method is proposed.Firstly,the practical structure of the back EMF observer system is obtained through analysis.Secondly,the performance of different controllers used for the observer is compared.Among them,the quasi-PR controller has extremely high gain at the fundamental wave angle frequency and a large bandwidth,which meets the design requirements best.Thirdly,the parametric design method of quasi-PR observer is discussed.Finally,simulation and experimental results show that the PMSM control system based on quasi PR position observer has good steady-state and dynamic performance.Aiming at startup problem,I/F starting method is adopted to control the surface mounted permanent magnet synchronous motor(PMSM)at low speed.On the basis of introducing the principle of the I/F startup method,the self-stability of the currentfrequency ratio startup method is analyzed.Finally,the I/F startup method is simulated and experimentally studied.Aiming at switching Problem,a new switching method is proposed.Firstly,the reasons of the current,torque and speed fluctuation caused by traditional switching methods are analyzed.Aiming at this reason,a weight-based switching method is proposed to eliminate current,torque and speed fluctuation completely,and realize the smooth switching of permanent magnet synchronous motor sensorless control from low speed to medium and high speed.