Robust adaptive observers for induction motor drives

In this paper a robust observer for determining the flux vector of the induction machine is proposed. The observer works well also for large signal dynamics, including speed reversal, and its performance is tested by simulations. The robustness with respect to parametric variations is considered and a new algorithm is proposed for on line determination if the rotor time constant. Digital implementation is made possible with finite sampling time constraining the observer dynamics inside the physical limits of the induction motor by introducing suitable auxiliary control loops.