A Speed Adaptive Scheme-Based Full-Order Observer for Sensorless Induction Motor Drives in Low-Speed Regenerating Operation Range

Stability of the adaptive full-order (AFO) based-speed-sensorless induction motor (IM) drives in regenerating operation range is still a challenging problem. In this paper, the neglected estimated flux error is introduced to the speed adaptive scheme by rotating the estimated current error vector to improve the accuracy and the stability of the speed estimator, especially in low-speed regenerating region. Furthermore, the feedback gains are designed based on Routh-Hurwitz criterion and verified by the stability analysis. With the proposed speed estimation scheme and the feedback gains, the unstable region in the low-speed regenerating operation range is significantly reduced, namely, the stability of the speed estimation is guaranteed. The experimental results on an ARM-based 2.2 kW IM experimental setup highlight the effectiveness of the proposed method for its performance in the low-speed regenerating region.