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Advances in Power Electronics
Volume 2011 (2011), Article ID 970364, 8 pages
http://dx.doi.org/10.1155/2011/970364
Research Article

A New Sensorless MRAS Based on Active Power Calculations for Rotor Position Estimation of a DFIG

Department of Electrical and Computer Engineering, IST, Technical University of Lisbon (TULisbon), 1049-001 Lisbon, Portugal

Received 29 November 2010; Revised 3 March 2011; Accepted 25 March 2011

Academic Editor: Henry S. H. Chung

Copyright © 2011 Gil Domingos Marques and Duarte Mesquita e Sousa. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A sensorless method for the estimation of the rotor position of the wound-rotor induction machine is described in this paper. The method is based on the MRAS methodology and consists in the comparison of two models for the evaluation of the active power transferred across the air gap: the reference model and the adaptive model. The reference model obtains the power transferred across the air gap using directly available and measured stator variables. The adaptive model obtains the same quantity in function of electromotive forces and rotor currents that are measurable on the rotor position, which is under estimation. The method does not need any information about the stator or rotor flux and can be implemented in the rotor or in the stator reference frames with a hysteresis or with a PI controller. The stability analysis gives an unstable region on the rotor current dq plane. Simulation and experimental results show that the method is appropriate for the vector control of the doubly fed induction machine under the stability region.