Robust adaptive full-order observer design with novel adaptive scheme for speed sensorless vector controlled induction motors

This paper proposes a novel design of a robust adaptive full-order observer for sensorless vector controlled induction motors. The adaptive full-order observer is known to become unstable in a major part of the low speed and regenerating region and this prevents the sensorless vector controller from operating an induction motor successfully. In this paper, the error system of the adaptive full-order observer is considered again, a novel adaptive scheme for the speed identification is proposed in order to stabilize an adaptive full-order observer. Moreover, the observer gain design is also proposed for robust stability improvement against the speed identification error (delay) and the stator resistance variation. Finally, several simulations verify feasibility of the proposed strategy.