Estimation of mechanical signals in induction motors using the recursive prediction error method

Sensor feedback of mechanical quantities for control applications in induction motors is troublesome and relative expensive. In this paper, a recursive prediction error (RPE) method has successfully been used to estimate the angular rotor speed and the driving torque in an induction motor. The signals are estimated from measurements of stator voltages and currents only, without any knowledge of the load. The performance of the estimator is evaluated by comparing the estimated signals by the measured ones. The RPE method is guaranteed convergence in contradiction to the extended Kalman filter which is frequently used for joint parameter and state estimation in induction motors. A modified structure of the motor model has shown to improve the performance of the estimator