Magnetic bearing hydrogen recirculation pumps enable high-speed, wear-free operation but are sensitive to flow-induced disturbances. This study proposes a cascade-structured disturbance observer (CDOB) that fuses rotor displacement and bearing current signals to achieve robust disturbance estimation under model uncertainties, with low-pass filtering to ensure stability. The proposed method is validated through simulations and repeated experiments at multiple axial positions. Based on raw displacement signals, the CDOB reduces the average peak-to-peak axial displacement by approximately 35% compared with a traditional disturbance observer. Under axial offset conditions of −100 μm and +100 μm, the CDOB consistently achieves average displacement reductions of approximately 23% and 24%, respectively, demonstrating consistent disturbance suppression and robustness across repeated tests. These results indicate that the CDOB provides an effective and practical solution for disturbance suppression in magnetic bearing systems.
Zheng et al. (Mon,) studied this question.