Abstract：Full-order adaptive observers are successfully and widely applied for the speed- sensorelss induction-motor drives. However, it is well recognized that the rotor speed estimation based on the adaptive full-order observer of induction motor can be unstable in the regenerative region. Based on the open loop full-order adaptive observer, the necessary and sufficient conditions for the stability of the speed estimation and the flux estimation are analytically derived by the adaptive control theory. So it can be indicated that the unstable region will occur in the regenerative mode with large enough regenerative load, and then the question of when and how this instability phenomenon occurs is solved. At the same time, to see the resultant drive performance including the stability on the torque-speed plan, the stability boundary is derived. The instability region in the low speed regenerating mode can be remedied by increasing the flux amplitude within a reasonable range. Simulation and experiment are given to demonstrate the effectives of the proposed method for the adaptive full-order observer to enlarge the operation region of the regenerating mode.
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2014, Vol. 29 
