A robust control for induction motor using a variable structure model reference adaptive control (VS-MRAC)

This paper presents an angular shaft speed control scheme of an induction motor. The induction motor modelling is performed through vector control with rotor flux orientation. The used control strategy is variable structure model reference adaptive control, that is applied to control uncertain plants. Its main characteristics are the use of a switched control law under a structure with a reference model and the need of only the input and output measures of the plant. The system is formed by a 0.25 hp induction motor with a squirrel cage rotor, supplied by a voltage source inverter with pulse width modulation and current control, and a Pentium-100 MHz microcomputer with acquisition cards. Practical results are presented upon different conditions of system functioning, assuring the efficiency of this strategy related to its robustness to load disturbances and parameters variations