Research On Sensorless Vector Control Algorithm For Permanent Magnet Synchronous

In recent years,permanent magnet synchronous motor(PMSM)have been widely used in high-performance speed control systems due to its simple structure,stable output torque,high reliability,and excellent control performance.However,a disadvantage of using vector control methods to control PMSM is that a position sensor is required to obtain the rotor position of the motor.The position sensor increases the size and weight of the motor and reduces the system’s reliability,making it unsuitable for certain applications.Therefore,this paper studies sensorless algorithms for PMSM in the low-speed,mediumhigh speed,and wide speed range.After analyzing the basic mathematical model of PMSM,a vector control system with a sensor is constructed.The control parameters of the system’s speed control loop and current control loop are optimized,and the dynamic performance of the system is analyzed through simulation.In the study of the sensorless algorithms in the low-speed range,the performance of the rotation high-frequency voltage injection method and the pulse high-frequency voltage injection method is compared through simulation by injecting high-frequency voltage signals with the same frequency and amplitude.The conclusion is that the pulse highfrequency voltage injection method has less interference on the operation of the motor,and the performance is nonlinearly related to the speed.In the study of the sensorless algorithms in the medium-high speed range,through theoretical analysis and simulation experiments,it is concluded that the sliding mode observer method has stronger robustness and requires less computational power than the model reference adaptive system.Considering the chattering problem caused by the sign switching function in the traditional sliding mode observer,a new segmented switching function is proposed to reduce system oscillation and ensure the convergence speed of the sliding mode observer.In the study of the composite sensorless algorithms in the wide speed range,a composite algorithm that nonlinearly weights the two algorithms of pulse high-frequency voltage injection and sliding mode observer is proposed.Compared with the linear weighted composite algorithm,which has the defect of multi-segment weighting function that does not conform to the nonlinear relationship between the performance of the two algorithms and the speed,the proposed algorithm not only realizes accurate observation of rotor information but also smoothly switches between the two algorithms.The error in the medium-high speed range can be controlled within 2%,and the steady-state error in the transition speed range is relatively reduced by 10%.