An adaptive nonlinear control algorithm for induction motors

In this paper an adaptive nonlinear controller for the induction motor is presented. The proposed system consists of two distinct control loops: the inner loop which gives the exact asymptotic motor model linearization, and the outer one which provides for a perfect model following control of the rotor speed. The controller imposes torque and rotor flux references starting from the rotor flux estimation obtained by means of an extended nonlinear observer, which also estimates rotor speed and load torque. Rotor resistance as well as mutual and auto inductances, which vary during operation, are estimated by using the least square method. The proposed control system has been successfully tested by means of simulations. This paper deals with the main theoretical aspects and presents some significant simulation results