Analysis of the stability and the consumption of an electrodynamic bearing for different operation conditions

In centering electrodynamic bearings, the guiding forces result from the interaction between eddy currents generated by a magnetic flux variation in conductors and the magnetic field. Predicting the dynamical behavior of this kind of bearings is not easy given the interactions between the electromagnetic nature of the forces and the rotational machinery aspects. In this paper, an electromechanical model, able to explain, predict, analyze and simulate the dynamical behavior of bearings submitted to eddy current forces, is applied on a homopolar null-flux electrodynamic bearing. The identification of the model’s parameters is done based on quasi-static FEM simulation results. Thanks to the insight the electromechanical model gives on the physics involved in the bearing, the dynamical stability and the stiffness of the bearing are analyzed as a function of the bearing spin speed. For various operation conditions like a constant external load or a static unbalance, the behavior of the electrodynamic bearing is simulated and examined using the electromechanical model. For all these operation conditions, the influence of the external damping, necessary to stabilize the system is analyzed. The amount of necessary damping to introduce is discussed and also its impact on the overall bearing consumption.