Abstract
Because the magnetic force has nonlinear characteristic, nonlinear phenomena may occur in the rotating machinery supported by magnetic bearings. This study derives the fundamental nonlinear model of the magnetic bearing by transforming the magnetic flux densities of magnetic poles into the symmetric representation form. The PI control characteristics of amplifier and delay characteristic of magnetic force for the control electric current are considered in the modelling. The nonlinear vibration analysis can be performed both simply and acurately by utilizing this derived model. The influences of the dynamical parameters of both PD control and PID control are clarified, and obtained theoretical results are validated by the experiment.
