Parameter Stabilization Adjustment Method for Stability Enhancement of Speed-Sensorless Induction Motors

Speed-sensorless induction motor drives (SSIMDs) are widely used in rail transportation applications, which use an adaptive full-order flux (AFO) observer a lot for speed estimation. When the motor operates in the low-speed regenerating region, the AFO has an unstable region. For this problem, there are a number of papers proposing different solutions. In contrast to previous papers, this paper proposes a parameter stabilization adjustment (PSA) method to enhance the SSIMD system robustness. First, the relationship between q-axis current error and speed error is derived. On the basis, the feedback gains are designed to stabilize the SSIMD system based on Routh-Hurwitz Criterion. Then, to complete the design of PSA, the gain coefficient is introduced and designed based on the difference between the actual and estimated rotor flux. Finally, the validity of PSA is confirmed by theoretical and experimental comparison with existing methods.