Sensorless induction motor system and control method thereof

A method of controlling a sensorless induction motor system including an electric motor, which includes a stator having windings forming a plurality of phases and a rotor having permanent magnets, and a control unit for controlling driving of the electric motor by controlling a voltage applied to the stator in each phase thereof, the method comprising:

• applying, by the control unit, a plurality of sampling pulse voltages to the stator in respective phases thereof, and estimating a position of the rotor through a first rotor position vector having a greatest deviation of an induced current;
• and
• comparing, by the control unit, an induced current deviation of a second rotor position vector having a second greatest deviation of the induced current with an induced current deviation of the first rotor position vector, and determining whether or not the permanent magnets are demagnetized.