Motor demagnetization detection method and motor demagnetization detection device

A motor demagnetization detection device, suitable to detect demagnetization of a motor, wherein the motor demagnetization detection device comprises:

• an encoder, configured to estimate a rotation angle of the motor;
• a current sensing device, configured to estimate a three-phase current value of the motor;
• and
• a controller, coupled to the encoder and the current sensing device;
• wherein the controller calculates a speed of the motor according to the rotation angle;
• wherein when the controller determines that the motor maintains a first steady state according to the speed, the controller receives the three-phase current value to obtain and store a first steady-state data;
• wherein when the controller determines that the motor maintains a second steady state according to the speed, the controller receives the three-phase current value to obtain and store a second steady-state data;
• wherein the controller calculates and stores an equivalent magnetic flux according to the first steady-state data and the second steady-state data;
• wherein the motor is repeatedly driven to maintain the first steady state and the second steady state, the controller updates the first steady-state data and the second steady-state data according to the three-phase current value, and again calculates and stores the equivalent magnetic flux to generate a plurality of equivalent magnetic fluxes;
• wherein the controller calculates a magnetic flux change according to the equivalent magnetic fluxes, and the controller issues a demagnetization warning according to a comparison result of the magnetic flux change and a demagnetization warning value.