Design of a MRAS, Speed and Flux Estimators used in Sensorless Control of Induction Motors

Model reference adaptive system (MRAS) basedtechniques are one of the best methods to estimate the rotorspeed. Speed and torque control of an induction motor is usuallyattained by application of a speed or position sensor. However,these require the additional mounting space, reduce thereliability and increase the cost of the motor. The recent trend infield oriented control (FOC) is towards the use of sensorlesstechniques that avert the use of speed sensor and flux sensor.This paper seeks to provide a direct comparison between twotechnics of induction motor MRAS based speed estimators, onebased on the rotor flux and the other based on the back EMF.Comparison between the two techniques is made throughcomputer simulations.

Keywords:

Induction motor drive, adaptive observer MRAS, stability analysis,

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[1] H. Kubota and K. Matsuse, “ DSP-Based Speed Adaptive Flux Observer of Induction Motor”, IEEE Transactions on Industry Applications, vol. 29, no.2, 1993. [2] C. Schauder, “Adaptive speed identification for vector control of Induction Motor without rotational transducers”, in Conf. Rec. IEEE IAS Annu. Mtg., p. 493-499, 1988. [3] J. Holtz, “Methods for Speed Sensorless Control of AC Drives”, Published i K. Rajashekara (editor) Sensorless Control of AC Motors. IEEE press book. 1996. [4] M. Rashed and F. Stronach, “A stable MRAS-based sensorless vector control induction motor drive at low speeds”, in Conf. Rec. IEEE IEMDC, 2003. [5] M. Suman and C. Chakraborty, “Model Reference Adaptive Controller- Based Rotor Resistance and Speed Estimation Techniques for Vector Controlled Induction Motor Drive Utilizing Reactive Power”, IEEE Transactions on industrial electronics, vol.55, no.2, 2008. [6] C. Chaigne, E. Etien, S. Cauet, L. Rambault, “Commande vectorielle sans capteur des machines asynchrones”, Hermes science, Lavoisier, 2005. [7] N. Marwali and A. Keyhani, “ Comparative Study of Rotor Flux Based MRAS and Back EMF Based MRAS Speed Estimators for SpeedSensorless Vector Control of Induction Machines”, IEEE Industry Applications Society Annual Meeting, New Orleans, Louisiana, 1997. [8] M. Rashed and F. Stronach and P. Vas, “A stable back EMF MRASbased sensorless low speed induction motor drive insensitive to stator resistance variation”, IEE Proc-Electr, Power Appl, vol.151, no.6, 2004.