Abstract
To achieve stable torque control, rotor information on squirrel-cage induction motors was obtained for the first time by using highly sensitive magneto-impedance micromagnetic sensor. The magnetic field detected near the edge of the rotor shaft was estimated to be proportional to the rotor current with a slip frequency (psf/2) and a torque when the motor was driven with a constant V/f inverter. Stable control of the stationary torque was realized independently of the motor temperature variation.
