Stability and Dynamic Performance Improvement of Speed Adaptive Full-Order Observer for Sensorless Induction Motor Ultralow Speed Operation

Although the stability of a speed adaptive full-order observer (AFO) has been studied for a sensorless induction motor (IM) ultralow speed operation, few researchers concern its dynamic performance simultaneously. To address this problem, this article proposed a novel feedback gain selection principle of an AFO considering both stability and dynamic performance. Compared with the conventional stability-based feedback gain selection, the proposed method applied the zero-point locus diagram and Bode diagram to further limit the range of stabilized feedback gain, leading to improved dynamic performance. Moreover, the robustness of the AFO is guaranteed with the proposed feedback gain under IM parameter mismatch. The validity of the proposed method is confirmed by comparative experiments.