Novel fuzzy adaptive sensorless induction motor drive

Investigations were carried out on a novel sensorless drive for induction motors, based on the combination of an open-loop (OL) estimator and a steady-state (SS) estimator. The novelty of this new sensorless structure is obtained by an intelligent mixing of the OL estimator response with the SS one. A fuzzy system weights the two estimated speed values according to the motor operating point. Then, the final speed value is obtained averaging the previously weighted speed values. Moreover, the OL estimator response is improved by means of using a fuzzy-controlled adaptive filter that selects the optimum cutoff frequency. The aim of this paper is to obtain a moderate performance sensorless drive for induction motors that could be easily implemented for industrial applications without a high computational effort. Simulation and experimental results illustrate the operation and performance of the proposed fuzzy-logi-based sensorless drive.