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

Abstract

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.