An Improved Rotor Resistance Estimator for Induction Motors

In this paper, an online rotor resistance estimator for induction motor adaptive control is presented. The proposed algorithm is an improvement of the previous work Kenne et al.. The rotor resistance scheme uses the rotor speed, the stator current, voltage provided by the controller, time-derivatives of the stator current and voltage. The time derivatives of the stator current and voltage are estimated by using 2nd order sliding mode observer. The convergence of the estimated rotor resistance to the nominal value in finite time is achieved when the classical persistent excitation condition is satisfied by the input signal. Experimental results with 100% variation of the stator resistance and online variation of the rotor resistance show that the proposed algorithm gives better performance compared to the previous work.