Robust variable structure speed control for induction motor drive

In order to eliminate the effect of parameter variation on field-oriented c ontrol for induction motor drive, an adaptation algorithm for tuning the ro tor time-constant is proposed. Based on the adaptive observation of the rot or flux linkages, the rotor time-constant is adapted to obtain an exact ind irect-field-oriented control (IFOC). In this proposed algorithm, a related function to the variation of the rotor time-constant is designed, then the accurate slip frequency needed for IFOC is obtained from this error functio n through a PI-type (proportional-integral) filter, Furthermore, a novel va riable structure speed control with integral sliding surface is proposed un der the adaptive held-oriented operation. By means of the variable structur e speed control, the dynamics of motor speed has the property of an exponen tially convergent rate. Using the proposed adaptive held-oriented control a nd the variable structure speed control, the IFOC is robust to the variatio n of the rotor time-constant and the speed control is insensitive to parame ter uncertainty and load disturbance. Finally, some simulation and experime ntal results are presented to validate the effectiveness.