Robust adaptive full-order observer design based on γ-positive real problem for speed sensorless vector controlled induction motors

This paper proposes a design of a robust adaptive full-order observer based on γ-positive real problem for sensorless vector controlled induction motors. The adaptive full-order observer is known to become unstable in a major part of regenerating-mode and low-speed region, and this prevents the sensorless vector controller from operating an induction motor successfully. In this paper, designs of a observer gain and adaptive schemes based on γ-positive real problem are proposed. Firstly, the error system of the adaptive full-order observer is reconsidered, requirements of adaptive full-order observer with stator resistance identifier are described. Next, in order to satisfy all requirement of the robust adaptive observer, the designs of the observer gain and adaptive schemes for speed and stator resistance are shown. Finally, several experimental results show the feasibility and the effectiveness of the proposed design strategy.