LTI modelling of active magnetic bearings by means of system identification

Abstract

A relatively unknown phenomenon in active magnetic bearings (AMBs) is that the frequency content of their rotor position signal can induce nonlinear behaviour in the bearings. The existence of such frequency-induced nonlinear behaviour is experimentally and theoretically confirmed. Frequency-induced nonlinearity is characterised by means of a novel graphical representation. The resultant graph is quite useful in the specification of suitable excitation signals when AMBs are to be modelled by means of system identification.