ROTOR TIME CONSTANT ESTIMATION DEVICE FOR INDUCTION MOTOR

PROBLEM TO BE SOLVED: To provide a rotor time constant estimation device for an induction motor that always generates torque of constant level under less influence of a peripheral environment or operation conditions.SOLUTION: The rotor time constant estimation device for an induction motor is configured to receive a d-axis current command and a q-axis current command, to output a q-axis voltage command, to output a q-axis voltage estimated value, to output a variation value of a rotor time constant as a difference between the q-axis voltage command and q-axis voltage estimated value, to add the variation value of the rotor time constant to a rotor time constant, and to output the changed rotor time constant.