An approach to the fuzzy variable structure control of induction motors

This paper concerns fuzzy sliding mode control. A new approach, which was first introduced by Ben-Ghalia et al., is applied to the cascade sliding mode control of an induction motor fed by a PWM voltage source inverter, which operates in a fixed reference frame. For this purpose, a new decoupled and reduced model is first proposed. Then, a set of simple surfaces and associated control laws are synthesized. A piecewise smooth control function with a threshold is adopted. However, the magnitude of this function depends closely on the upper bound of uncertainties, which include parameter variations and external disturbances. This bound is difficult to obtain prior to motor operation. To solve this problem, a new fuzzy sliding mode control applied to an induction motor drive is presented. The fuzzy sliding mode controllers are designed in order to improve the control performances and to reduce the control energy and the chattering phenomenon. Simulation results reveal some very interesting features and show that the proposed fuzzy sliding mode controller could be considered as an alternative to the conventional sliding mode controllers of induction motors. (author)