Different techniques for real time estimation of an induction motor rotor resistance in sensorless direct torque control for electric vehicle

Four different techniques for rotor resistance estimation in sensorless dir ect torque control (DTC) are studied and compared. Since input voltage cont ains harmonics, many available techniques cannot be applied in the DTC. Thr ee of the four above-mentioned techniques are the generalization of the pre vious methods. The fourth technique is a new one, which is applied by the a uthors. Speed of motor is estimated based on the governing equations of the induction motor and DTC. The resistance is estimated above rated speeds, w hich were required in electric vehicles (EV's). Although the four technique s enable to estimate the rotor resistance in real time, the new technique a nd TE (torque-error) method have some advantages over two other techniques.