Speed Sensorless Indirect Stator Field Oriented Control of Induction Motor Based On Luenberger Observer

The interest for sensorless drives has been constantly raising during the last years. The fact that the rotor speed is not measured but estimated has several benefits. The drawbacks are lower speed range. Several estimation methods have been proposed to resolve this problem. In the conventional methods to estimate the rotor speed of the induction motor, when the estimated speed is transformed into the sampled data model using the mathematical equations, the sampled data model has a modelling error, which in turn produces an error in the speed estimation. The error included in the estimated speed is removed by the use of a low pass filter. As a result, the delay of the estimated speed occurs in transient by the use of low pass filter. This paper propose a novel closed loop rotor speed observer of the induction motor to resolve the problem of a conventional speed due to the delay of the estimated speed in low range and in field weakening regions. Besides, this paper presents a method to estimate exactly the rotor speed by using Luenberger observer. With the proposed algorithm, the accuracy of the estimated is guaranteed when the components of stator current converge to their actual one. The validity of the proposed method is verified by the simulation results