A polar coordinate-oriented method of identifying rotor flux and speed of induction motors without rotational transducers

In this paper, we propose a novel method of identifying rotor flux and speed of induction motors without rotational transducers. Our identification method does not involve any pure integration, which has been a main source of performance deterioration in most prior works. This is made possible by formulating the identification problem in the polar coordinate frame. It does not contain any parameters which need be re-tuned according to hardware configurations or operating conditions. Moreover, the motor speed does not have to vary slowly for the convergence of our flux and speed estimator. Various experimental results as well as a rigorous convergence analysis are presented to demonstrate the practical use and generality of our identification method. For our experimental work, we have built a prototype drive system, in which all algorithms for control and identification are implemented digitally on a digital signal processor.