Nonlinear adaptive control for hybrid foil-magnetic bearing

A hybrid foil-magnetic bearing (HFMB) is a combination of the gas foil bearing (GFB) and the magnetic bearing (MB), which takes advantages of each individual bearing and compensates for their inherent weaknesses each other. However, control of the HFMB is different from that of the AMB considering the varying dynamic stiffness and damping coefficients of the GFB. This paper presents an adaptive control method for the HFMB to simplify the controller design and improve the performance of the rotor-HFMB system. First, the characteristic modelling method is used to establish a decentralized second order model of the HFMB. The model parameters are achieved by real-time parameter identification. Then, the golden section controller is used to adapt the parameter variation of the GFB and ensure the stability of closed loop system. Finally, numerical simulations are performed to verify the validity of the presented method. The simulation results show good performance of the presented controller compared with a conventional PD controller.