Research On Position Sensorless Rotor Position Estimation Method Of Permanent Magnet Synchronous Motor

In the variable frequency air conditioner control system,the permanent magnet synchronous motor is the main driving motor.Whether it is vector control or direct torque control,it is necessary to obtain an accurate rotor position.The result of the rotor position estimation determines the overall performance of the control system.This thesis studies the rotor position estimation method of permanent magnet synchronous motors.The main work is as follows;First,According to the mathematical model of the motor and the working principle of the flux linkage observer,the voltage flux linkage observer is first improved to solve the problems of DC offset and amplitude attenuation,and then it is combined with the current flux linkage observer to form a hybrid Chain observer and phase compensation of the hybrid magnetic chain observer to solve the phase error problem existing at medium speed.When the motor runs at low speed,the current model observer works,and when the motor runs at medium and high speed,the improved voltage model observer works.Thus,the optimal flux estimation value is obtained in the full speed range.Second,After the flux vector is obtained through the flux observer,the combined SOGIFLL and improved PLL are used to obtain the rotor position and speed estimates.The phaselocked loop is improved to make its filter adaptive by A notch(ANF)and LPF are cascaded,which can filter out specific order harmonics in the rotating coordinate system.In the rotor position estimation process,a new algorithm based on a type of control is used to make it possible to estimate the rotor position in a stationary coordinate system and speed up the system’s response speed.A hybrid flux observer and an improved phase-locked loop are then combined to estimate the rotor position.Third,According to the rotor estimation algorithm proposed in this thesis,based on the simulation,set up an experimental platform and apply it to a variable frequency air conditioner.The experimental results prove that the combination of a magnetic flux observer and a composite SOGI-FLL and an improved PLL can accurately estimate the rotor position and track the changes in the rotor speed faster.