Nonlinear control of induction motor with unknown rotor resistance and load adaptation

On the basis of a dynamic model obtained under a special nonlinear coordinate transform on a d-q axis model (the stationary reference frame) of an induction motor, a nonlinear adaptive controller for speed tracking control with unknown load torque is proposed in this paper. The controller is made to work under the condition that all the parameters except the rotor resistance of the induction motor are known a priori. The underlying control theories include the indirect vector control and the maximal power transfer of the motor. To be rigorous, the proposed control scheme is derived from the Lyapunov stability theory. The simulation results are also given to show the effectiveness of the presented control scheme