Bifurcation Onset Delay in Magnetic Bearing Systems with Auxiliary Bearing and Time Varying Stiffness

Auxiliary bearings are used in magnetic bearing systemsto protect bearings from damage. These bearings are in contact with rotor temporarily. This contact associated with intermittent contact forces which change the system dynamic behavior. These include vibration instability and thermal stresses. The system is simulated to clarify the role of two different control methods in synchronous and asynchronous responses.This is carried out using linear PD controller and time varying stiffness. Rotor whirl orbit and power spectrum in magneticbearing with time varying stiffness reveals better behavior in some cases. Rotational speed range with synchronous response increases. A delay in the onset of bifurcation depicts an improved rotor dynamic performance.