Measurement of rotor time constant taking into account magnetizing flux in the induction motor

Rotor time constant is essential for high performance motor control in the induction motor. A simple and exact measurement method of rotor resistance and rotor time constant of induction motor is proposed. A DC current is injected to the magnetizing inductance, and then the magnetizing current is discharged to the rotor, so that the voltage is taken at the stator. Then the measured stator voltage has information of rotor time constant as a function of magnetizing current. In this paper, rotor time constant obtained from conventional method and the proposed method are compared. The accuracy of the measurement is tested with a vector controller by a linear relation between the input torque command and output torque at steady state.<
>