الفهرس Only 14 pages are availabe for public view
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Abstract
AC motors. especially the induction motors are now the most commonly used motors in industry due to their reliability. ruggedness and low cost. On the other hand. induction motors are nonlinear systems that are difficult to control. Moreover, the parametric deviation and disturbance load torque affect significantly the dynamic perfonnance and stability in practical implementation. Several approaches have appeared in the literature to improve the perfonnance of induction machine drive. The basic schemes of scalar, vector and adaptive control are briefly reviewed.
The aim of this study is to apply an adaptive load torque estimation combined with nonlinear sliding-mode approach so that the rotor Ilux and speed dynamics arc decoupled and controlled through a linear reference model. The proposed scheme is compared with the most efficient techniques; namely, field-oriented control and direct-torque control. It is also compared with the sliding-mode control system combined with proportional-integral controllers recently presented in the literature. With the proposed scheme, the controlled induction motor drive possesses the advantages of fast transient response and robustness against large parametric uncertainties and load torque variations.
To avoid the use of !lux probes which complicate the design of induction motor and increases its cost. two observers arc given. The first observer is used to estimate the rotor flux to implement the proposed scheme. The second is a sliding-mode observer to estimate the stator !lux and torque ~hich arc used for sensorless direct-torque control scheme. Robustness to motor parameter uncertainties and unmodcled load torque variations i~
included.