An online rotor time constant estimator for induction machine

Indirect field oriented control for induction machine requires the knowledge of rotor time constant to estimate the rotor flux linkages. Here an online method for estimating the rotor time constant and stator resistance is presented. The problem is formulated as a nonlinear least-squares problem and a procedure is presented that guarantees the minimum is found in a finite number of steps. Experimental results are presented. Two different approaches to implementing the algorithm online are discussed. Simulations are also presented to show how the algorithm works online.