Research On Active Disturbance Rejection Control Strategy Of Sensorless PMSM Drives

Permanent magnet synchronous motors(PMSMs)have the advantages of high torque density and good dynamic performance,which make them favored by the industrial field.The position sensorless control technology of PMSM has achieved remarkable results in reducing system cost and improving system robustness.The high-frequency voltage injection method is an effective way to realize the position sensorless operation of PMSM in zero and low speed.However,factors such as inverter nonlinearity have severely affected the rotor position estimation results.In addition,model uncertainties and external disturbances degrade the disturbance rejection capability of the position sensorless control system.This paper studies the above issues,and the research scheme is as follows.Firstly,the improved speed and rotor position extraction method based on high-frequency square-wave voltage injection is studied.The current variations of the stationary reference frame in the positive and negative injection periods are processed for subtraction,thus the robustness of the speed and rotor position estimation to voltage errors is improved.Afterwards,the rotor position error is obtained by the normalization and the heterodyning.By converging position estimation error to zero,the speed and the rotor position can be estimated via a Luenberger observer.Then,in order to improve the robustness of the control system to model uncertainties and external disturbances,the enhanced nonlinear active disturbance rejection speed control strategy is studied.In view of the limitations of conventional linear and nonlinear extended state observer(NLESO),considering the accuracy and speed of disturbance estimation,a nonlinear function is proposed and its description function is established to expand the disturbance range to deal with.Based on it,the enhanced active disturbance rejection control(NLADRC)is constructed.The cascaded NLESO is used to estimate the disturbances in real time,and the control law is designed to compensate the disturbances,so the speed can be regulated with high robustness.Further,the performance analysis of the enhanced NLADRC based system is implemented.In order to simplify the performance analysis,the two nonlinearities in the cascaded NLESO are simplified,and the stability analysis of the enhanced NLADRC based system is carried out.Compare the disturbance estimation performance and stiffness performance of the conventional ADRC based system with the enhanced NLADRC based system,the advantages of the enhanced NLADRC based system are proved theoretically.Finally,the scheme proposed in this paper is verified by simulation platform and experimental platform.Both simulation and experimental results show that the proposed scheme can improve the robustness of the rotor position estimation to voltage errors and enhance the system disturbance rejection capability to model uncertainties and external disturbances.