Sensorless control of indirect field oriented induction machine drives

This document presents research results for developing speed sensorless control algorithms for indirect field oriented (IFO) induction machine drives using sliding mode theory. In addition the improvement of the control performance of an IFO induction machine drive is attempted by using an adaptive fuzzy logic and a chattering free sliding mode controller. However, design of controller as well as observer for such systems may not be a trivial problem, since the model of the induction machine is a multi-variable, fifth order and strongly coupled nonlinear system. When the rotor speed is available, field oriented control can be considered as a conventional control method, since by using the frame transformation control of torque and flux can be decoupled for a field oriented induction motor drive. However, when the rotor speed is not available via a speed sensor then the problem of designing a speed estimator structure arises. For last two decades, these two problems are the focus of many researchers and many different algorithms have been proposed. From the point of practical aspects, the most of the proposed algorithms are too complex. Since for industrial applications the most important aspects of a drive system are “simplicity and reliability,” in this work our objective is to design an induction machine drive system which is simple and reliable. For this purpose, first two robust control algorithms are proposed for the speed regulation. Second three new flux and speed estimation methods based on sliding mode theory are proposed. The simulation and testing results confirms the performance of the proposed algorithms.