Research On Position Sensorless Full Speed Control Strategy Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors(PMSM) have been widely used in industrial control,aviation,home appliances and many other control systems with the advantages of high efficiency,high power factor,high power density,and low temperature rise.High-performance permanent magnet synchronous motor control systems often need to rely on reliable rotor position information in real time,using sensors to obtain position information is currently the most common way,but the presence of sensors increases system cost,volume and reduce the reliability of the system,which limits the application of the control system.In recent years,position sensorless control technology has been widely used in home appliances,high-end equipment manufacturing and other occasions.The control system feeds back position information in real time according to internal physical relationships,Sensorless control technology overcomes the defects use of mechanical sensors that brought by the system.Thus,Sensorless control technology expands the application range of permanent magnet synchronous motors in some special occasions.How to further improve the position sensorless technology and apply it to some high-performance occasions is the current research hotspot in motor control.This paper takes the surface mount motor as the research object,and conducts research on its initial position identification,full speed range operation control strategy and other related issues.First of all,this paper briefly introduces the structure and physical characteristics of the permanent magnet synchronous motor,modeling and analyzing the mathematical model and vector control algorithm of the permanent magnet synchronous motor,and builds a position sensorless control system to lay a practical foundation for subsequent research on position sensorless strategies.This paper proposes an orderly voltage pulse injection method with demagnetization effect for the identification of the initial position of the rotor.The rotor position information is obtained based on the relationship between the response current difference and the electrical angle.This method solves the problem of rotor rotation in rotor pre-positioning;A high-frequency square wave voltage is injected into the direct axis,aiming at the low-speed operation of permanent magnet synchronous motor without a position sensor,and uses the firstorder moving average filter to extract the high-frequency response current envelope,then uses the phase-locked loop to extract the position information.High frequency injection is not sensitive to non-linear factors such as dead zone.The signal processing is simple,and the position observation accuracy is high.For high-speed operation without position sensors,this paper proposes an improved sliding mode observer with back-EMF error as the sliding mode output to address the phase lag and inherent chattering problems of traditional sliding mode observers.This method constructs a current observer based on the combined control law of proportional-integral sliding mode surface,saturation function,and exponential approach rate.The back-EMF signal is extracted by the back-electromotive observer,and a phase-locked loop is introduced to realize position detection.Finally,in order to realize the position sensorless full-speed domain control of the permanent magnet synchronous motor,this paper uses the speed and angle weighting method to realize the smooth switching from low speed to medium and high speed.Combining the theory of position sensorless control with full speed range running,this paper builds simulation analysis model and systematically establishes a position sensorless control system strategy.Finally,a system software and hardware platform based on DSP+FPGA was designed and built,and related experiments were carried out.The effectiveness of the position sensorless control algorithm is verified by experiments in this paper.