A robust controller for improving disturbance rejection in speed control of induction motors

Advances in nonlinear control theory, power electronics technology, and the availability of low cost high speed digital signal processors (DSP) stimulated the design of complex nonlinear control algorithms for induction motors. In this paper, a new method based on nonlinear auto-disturbance rejection controller (ADRC) has been developed for ensuring high steady-state speed accuracy in addition to high dynamic performance. Via the use of ADRC, the stability is guaranteed for the speed servo control and insensitivity to uncertainties and disturbances are obtained as well. To demonstrate the effectiveness of the proposed scheme, the ADRC is applied to the speed control of a 2.2 kW induction motor. The proposed control system has been successfully tested by means of simulations and experiments. The results show that the controller operates quite robustly under modeling uncertainty and measurement noise, and the speed response has much improved performance such as small overshoot and fast setting time