Sensorless control of permanent magnet synchronous motors based on virtual square-wave injection
YIN Hao
ZHU Longji
Abstract：The Permanent Magnet Synchronous Motor(PMSM)speed control systems typically calculate d-q axis current references directly using torque formulas,but these methods are sensitive to motor parameters and struggle to operate at the optimal working point.Sensorless control often employs high-frequency sinusoidal in-jection,but the use of filters reduces system bandwidth and response speed.This paper proposes a composite control strategy that integrates sensorless position estimation via high-frequency square-wave injection and Maximum Torque Per Ampere(MTPA)control based on virtual square-wave injection.The strategy applies virtual square-wave-injected MTPA to control the motor,injects high-frequency square waves into the current loop,and extracts rotor position information from the high-frequency current signals,achieving composite control of the PMSM.Simulation results verify the effectiveness of the proposed control strategy.The speed control system of a permanent magnet synchronous motor(PMSM)typically employs the torque formula to di-rectly compute the reference value for the d-q axis current.However,this method is sensitive to motor parame-ters and poses challenges in achieving optimal operating points.Sensorless control often utilizes the high-fre-quency sine wave injection method,but the implementation of filters can diminish the system's bandwidth and response speed.This paper proposes a novel composite control strategy that integrates the Maximum Torque Per Ampere(MTPA)derived from sensorless position observation with virtual square wave injection,achieved through the application of high-frequency square wave inputs to the permanent magnet synchronous motor con-trol system.In this approach,the motor is regulated by the MTPA introduced by the virtual square wave.The high-frequency square wave is injected into the current loop,allowing for the extraction of rotor position infor-mation from the high-frequency current signal,thereby facilitating the composite control of the PMSM.The ef-fectiveness of the proposed control strategy is validated through simulation results.
Keywords：permanent magnet synchronous motorMTPAvirtual square waveno position sensing
Publication Date：2025-10-30
Online Publishing Date：2025-11-06(First online date of this platform, not the publication date of the document)
Pages：5( 80-84 )