Research On Sensorless Control Technology Of Permanent Magnet Synchronous Motor In Full Speed Domain

In recent years,permanent magnet synchronous motor(PMSM)has become the first choice for high-performance speed control systems due to its smooth current,low noise,small torque ripple,large torque/inertia ratio,and low speed performance.Widely used in industrial and agricultural manufacturing,new energy electric vehicles,civil electrical equipment,aerospace exploration and other fields.How to improve the control performance of the PMSM speed control system,and effectively avoid the many limitations of the position sensor system,so that the controlled motor can accurately obtain the real-time information of the motor rotor without the position sensor,which has become a hotspot for scholars at home and abroad.The widely used PMSM position sensorless control method can be classified as follows:(1)methods based on motor back electromotive force,such as model reference adaptive method,sliding mode observer method and Kalman filter method.(2)Based on the high-frequency signal injection,the different types of extra high-frequency signals are superimposed on the fundamental frequency excitation of the motor,and the motor rotor position and rotational speed information is obtained by detecting the response of the motor to the high-frequency signal.The above two types of control strategies can better achieve the purpose of accurate observation of the rotor information of the motor.But,the former should not be used when the motor speed is low and the motor back electromotive force is small,and the latter may have insufficient influence of high frequency noise filtering.This paper first expounds the performance characteristics of PMSM,and then introduces the classification of motor,the establishment of mathematical model and the control method of PMSM vector,finaly the high frequency rotating voltage injection method,high frequency pulse voltage injection method,extended Kalman filtering(EKF)and unscented kalman filter(UKF)is analyzed and studied.Through theoretical analysis,it can be seen that the surface-mount PMSM is not suitable for high-frequency rotary voltage injection because of its equal cross-axis inductance and direct-axis inductance,and the salient pole effect is low.At the same time,through in-depth study of Kalman filter algorithm,it is found that compared with EKF,UKF has the advantages of high estimation accuracy and low computational complexity.In order to further improve the observation accuracy of the rotor position and improve the anti-interference ability of the controlled system,this paper proposes an improved scheme of the Sage-Husa estimator and the load torque feedforward compensation based on the UKF.The simulation model of the controlled PMSM system is built on the Matlab/Simlink platform.Finally,based on the above research and simulation analysis,aiming at the large estimation error of high frequency injection method at high speed of motor and the poor observation performance of Kalman filter algorithm at low speed of motor,this paper adopts high frequency pulse voltage injection method when the motor is below the specified low speed limit,and uses improved UKF algorithm when the motor is above the specified high speed point,while the transition region is designed.The composite algorithm realizes the smooth transition between the two detection modes,thus realizing the accurate estimation of the rotor position in the full speed range of the PMSM controlled system.The simulation results and analysis show that the sensorless rotor position detection and control strategy of PMSM in full speed domain is correct and effective.