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

Permanent magnet synchronous motor(PMSM)has the advantages of simple structure,high power density,and wide speed range.It has been widely used in high-performance control places.The traditional Hall sensor method for obtaining rotor position has a high cost and a low reliability,so sensorless control technology is gradually receiving attention.This paper studies the sensorless control within the full speed range of PMSM.Currently,sensorless control is divided into two categories: the zero to low speed domain and the medium to high speed domain.In the zero to low speed area,the rotor position is mainly detected by injecting high-frequency signals.This paper uses the high-frequency square wave voltage injection method instead of the traditional pulse high-frequency voltage injection method to realize the separation of high-frequency and fundamental signals without using filters.The position and speed information is extracted from the envelope through a phase-locked loop,and the initial polarity is judged through the current detection.The simulation has verified that square wave injection can reduce the position estimation error to 0.05 rad.It can improve the speed tracking effect and correctly determine the rotor polarity during the startup phase.The high-frequency injection method is difficult to achieve stable control in the medium to high speed domain.Therefore,the system needs to extract the position information by observing the back electromotive force,but the observation process is easily affected by the internal and external disturbances.A enhanced linear ADRC(ELADRC)sensorless control scheme is proposed.First,a LESO1 is used in the current loop to estimate the external disturbance which includes the back electromotive force.This LESO1 is designed based on the determined model;Secondly,a new LESO2 is designed to observe the internal disturbance caused by the change of PMSM parameters and the quality of current regulation.LESO1 regards the observed external interference as the known model information and transmits it to the LESO2 to improve the current regulation quality and observation accuracy.Moreover,a composite control scheme was proposed,which uses weighted functions to achieve smooth switching between the low-speed and the medium-speed regions of the algorithm.Finally,The drive board suitable for the PMSM control is designed and the motor test bench is built.According to the control scheme design experiment proposed in this article,it has been verified that the composite control scheme of the high-frequency square wave voltage injection and the ELADRC can control the position estimation error within 0.5 rad,and the rotor speed can converge to the expected speed within 0.5 seconds.The control performance of the PMSM has significantly improved.