Combined nonlinear controller and full order observer design for induction motors

In this paper new nonlinear output feedback controller schemes for induction motors are developed. A combined controller and observer design allows one to achieve singularity free tracking of the estimated torque and rotor flux without the need of flux measurement. An important contribution is the use of a full order observer with nonlinear gain. The controller design takes the observer dynamics into account. We can thus achieve faster convergence and smaller tracking errors. Moreover, this design eases the discrete time implementation of the overall control scheme. The scheme is extended to speed control allowing important practical features such as stator current limitation. Finally, some simulations are presented