Load-Torque Estimation Under Four-Quadrant Operation of Vector Controlled Three-Phase Induction Motor Using Stator Current and Voltages

This paper presents a sensorless load torque estimation method for the field-oriented controlled three-phase induction motors. The method uses the Γ-equivalent circuit of the induction motor to calculate the load-torque. The differential equations of the induction motor are simplified therefore the load torque estimation equation is obtained to calculate the torque of the three-phase motor. The proposed method estimates the load torque of the field oriented controlled induction motor accurately. The method is verified with simulations in MATLAB/Simulink in wide operating speed ranges under four quadrant operation of the field oriented controlled induction motor.