This work studies the technique of vector drive applied to three-phase induction
motor (IM), using as the control strategy fuzzy control and sliding mode control in
a setting here called Fuzzy Sliding Mode Controller (FSMC) . A dynamic model is
developed at IM in variable ’d - q’ which led to an electromechanical model state
space that exhibits strong nonlinearities . In this model the conditions that allow
vector control decouple the torque and flux at IM, so that their dynamic behavior
is similar to that observed in a DC machine are applied. In this condition, the
proportional and integral type (PI) controllers are implemented to control motor
speed and current loops, and computational simulations for tracking speed and
load disturbance are carried out, which lead to satisfactory results from the point
of view dynamic. In order to investigate the performance of nonlinear strategies in
this approach the study of control technique the switching structure of the sliding
mode type is displayed. A conventional sliding mode controller is implemented,
where it appears that, despite the excellent dynamic performance of the occurrence
of the phenomenon of ”chettering”precludes the application of this strategy in
actual tests. Thus, FSMC control strategy is proposed, trying to associate the
good result obtained with the dynamic sliding mode controller and the suppression
of the chettering, which is achieved by defining a layer switching fuzzy type. The
FSMC proposed controller is subjected to the same computational tests that the PI
controller, leading to superior results to the latter the transient dynamic response,
but with the presence of steady-state error. To attack this problem is implemented
one of the strategies Fuzzy FSMC combination with the action of PI control, where
the first seeks to operate in remote regions of the switching surface and the second
seeks to introduce the effect of integral action near the surface. The results show
the feasibility of the strategy in variable speed drive that demand high dynamic
performance.
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