Torque Sensors for Induction Motors Using Amorphous Microcore Field Sensors

The authors describe the use of amorphous core sensors as a means of achieving precision vector control in induction motors. This type of sensor detects a magnetic field proportional to the secondary current I2 flowing in the rotor end rings to determine the current I2 and electric torque. Eight sensor cores are placed around the rotor, reducing the effect of mechanical vibrations. Good output linearity was obtained, and the feasibility of constructing a precision vector control system with a torque feedback loop was demonstrated.