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

With the proposal of national carbon peak and carbon neutral goals,the rational utilization of energy has become a research hotspot.Permanent Magnet Synchronous Motor(PMSM)has the advantages of high operating efficiency,simple control,and large starting torque.The position sensor is usually used to extract the angle and speed of the rotor.However,under bad conditions,sensors are vulnerable to corrosion,vibration and other environmental factors,so sensorless control technology has been developed.This paper takes PMSM as the research object,aiming at the full speed domain sensorless control technology.In the medium and high speed domain,the mathematical model of PMSM is established,and the coordinate transformation theory is analyzed to provide a basic theoretical basis for the following article.In order to solve the problem of amplitude attenuation and phase delay in the estimation of back EMF by traditional sliding mode observer,a full order sliding mode observer is designed to eliminate the low-pass filter link,improve the estimation accuracy of rotor angle and speed,and eliminate the impact of cut-off frequency on the system.On this basis,the switching function is replaced by a saturation function,which effectively weakens the high-frequency chattering phenomenon caused by the state variables of the sliding mode observer when switching the sliding mode surface,and reduces the high-frequency harmonic content in the back EMF.The sensorless vector control system will generate 6k+1 harmonic in the back EMF estimated by the sliding mode observer due to the influence of the inverter nonlinear factors,especially the fifth and seventh harmonics.In order to eliminate the influence of harmonics on the estimation accuracy of angle and speed information,an adaptive hybrid generalized integral filter is proposed in this paper,which does not cause amplitude attenuation and phase delay at a specific speed,and has excellent filtering performance for the specific harmonics of the estimated back EMF.At the same time,in order to improve the estimation accuracy and anti-interference ability of the phase locked loop(PLL),a phase-locked loop based on the extended state observer(ESO)is designed to achieve stable extraction of rotor angle information.In the zero low speed domain,the high-frequency mathematical model of PMSM is established,and the limitations of pulse high-frequency voltage injection method and traditional high-frequency square wave voltage injection method are analyzed: the use of filters will reduce the system bandwidth.To solve this problem,an improved high-frequency square wave injection method is designed to eliminate the use of filters and improve the system bandwidth.