Demagnetization detection method and device for permanent magnet motor

The invention relates to the technical field of permanent magnet motors, and provides a demagnetization detection method and device for a permanent magnet motor. The method comprises the following steps: controlling a motor winding inductor of the permanent magnet motor to perform energy interaction, and obtaining an excitation current component of the permanent magnet motor when the motor winding inductor performs energy interaction; according to the excitation current component, the current amplitude of the excitation current component and the d-axis driving voltage of the permanent magnet motor, obtaining a local d-axis inductance value of the permanent magnet motor when the motor winding inductance performs energy interaction; determining the state of the permanent magnet motor according to the d-axis inductance value; wherein the current amplitude is determined according to the exciting current component and the current offset of the exciting current component; the state comprises a demagnetized state or