Designing a New and Effective Speed Sensorlesss Controller for 3-Phase Induction Motors by Applying De-Coupling Methodology
3-Phase Induction Motors are usually expressed by complicated non-linear models due to their non-linear nature,
hence controlling of 3-phase induction motors is a difficult task. To overcome this difficulty, this paper presents a new and
effective method for modeling stator current and estimating rotor flux of induction motors by applying Direct–Decoupling
Methodology. A nonlinear control approach with full state feedback linearization has been used to derive the decoupling
form of the 3-phase induction motors, furthermore, a linear Kalman filter has also been applied to construct an observer for
rotor flux. Then, a new current controller named “direct-decoupling”, based on exact linearization algorithm of the motor
current model has been proposed. The obtained linear system in a new state-space is very convenient to design the current
controller and the rotor flux estimator for 3-phase induction motors. Effectiveness of the new adaptive back-stepping
controller for 3-phase induction motors, and Kalman filter for observation of rotor flux has been verified by simulations and
experiments in wide ranges of the motors’ speed. Simulations and experiment results show clearly that the rotor flux can be
well estimated in all operating conditions, and performance of 3-phase induction motors under all dynamic modes can be
improved by using the new designed controller.
Index terms - 3-phase Induction Motors, Back-stepping, Direct-Decoupling, Kalman Filter, Non-linear control.