Experimental optimization of a hybrid foil–magnetic bearing to support a flexible rotor

• A test rig of a flexible rotor supported by hybrid foil–magnetic bearing is built.
• Experimental optimization procedure of hybrid foil–magnetic bearing is presented.
• The bearing performances are evaluated with rotor vibrations and motor currents.
• The resulting controller reduces both vibration and the energy consumption.

This paper presents experimental optimization of a hybrid foil–magnetic bearing to support a flexible rotor. Hybrid foil–magnetic bearing is a synergistic cross-fertilization of two oil-free bearing technologies: air–foil and magnetic bearing. First, an experimental set-up for a flexible rotor supported by a hybrid foil–magnetic bearing is built. Then, unbalance responses of the flexible rotor supported by two different bearings: air–foil and hybrid bearings are compared. The unbalance responses show that the rotor vibration in bending critical speed is more suppressed by the hybrid foil–magnetic bearing rather than the air–foil bearing only. Experimental optimization of the hybrid foil–magnetic bearing is performed by tuning control gains and offsets of the magnetic bearing. The resulting optimized controller for the hybrid foil bearing would not only improve vibration performance by 26% at bending critical speed, but also save the energy consumption of driving motor by 50% during run up test.