Theoretical and experimental investigation about dynamic characteristics of two-lobes misaligned pads hybrid foil magnetic bearings concerned active control

Hybrid foil magnetic bearing is a non-contact levitation bearing coupling with the active magnetic bearing (AMB) and gas foil bearing (GFB). Aiming at the question that GFB has obvious gas oscillation and lower stability, the two-lobe misaligned pads hybrid foil magnetic bearing (TLMP-HFMB) is proposed. Based on the N-S equation, Maxwell’s electromagnetic equation, and the equation of foil deformation, the theoretical model of dynamic characteristics about TLMP-HFMB is established and the effect of nominal clearance, static load, and loading sharing ratio on dynamic characteristics of TLMP-HFMB are calculated. The experimental platform of dynamic-load is set up and the effect of excitation amplitude, proportion gain, and difference gain on dynamic stiffness, dynamic damping, and loss factor of TLMP-HFMB are measured. The results show that the direct dynamic stiffness of TLMP-HFMB is higher than direct dynamic stiffness of GFB and AMB; the cross-coupled stiffness of TLMP-HFMB is lower than cross-coupled stiffness of GFB. The dynamic characteristics of TLMP-HFMB are decreasing with the increase of nominal clearance and loading sharing ratio, but the effect of rotational speed is just the opposite. The experimental results are in good agreement with the theoretical results; correctness of the proposed model is verified.