Induction Motor Torque Estimation Accuracy Using Motor Terminal Variables

Information about the torque produced by an electrical motor is needed in many applications such as hybrid drivetrains and in some applications where the shaft torque cannot be measured directly e.g. because of vibrations or other physical limitations. This paper investigates the torque determination accuracy using the voltage and current time domain data obtained from motor terminals using a power analyzer. The calculated torque values are compared with the measured values obtained with a state-of-the-art torque transducer. The results are analyzed in 16 different operating points with torque values of 25%, 50%, 75% and 100% of motor rated torque and supply frequency values of 25%, 50%, 75% and 100% of rated motor frequency. Measurement results with a sinusoidal generator supply and a converter PWM supply are used in the comparison.