A New Sliding Mode Flux and Current Observer for Direct Field Oriented Induction Motor Drives

Abstract

A direct field orientation (DFO) control for an induction machine is designed and implemented using a new sliding mode technique. The rotor flux is estimated using the current model flux observer. A close loop flux observer, based on the current estimate error, is then constructed. A unique feature of the proposed observer is that the flux and current observers include a sliding function, which is a derivative of the flux. Therefore, when the estimated current converges to the measured one, the sliding function itself is integrated to calculate the flux magnitude and angle. The observer stability is verified via Lyapunov stability analysis. Simulation and experimental results are presented to show the performance of sliding-mode based DFO control for an induction motor drive system. (C) 2002 Elsevier Science B.V. All rights reserved.