Dynamical Electromechanical Model for Magnetic Bearings

Magnetic bearings are electromechanical systems. From a mechanical point of view, their modeling is plainly related to general rotor dynamics modeling. But the forces acting between the rotor and the stator are of an electromagnetic nature. This paper presents the analysis of the potentially unstable dynamical behavior of magnetic bearings. It adopts an electromechanical point of view and represents the forces acting on the system by dampers, springs, and an electrical phase shift. The coefficients of the model are found by parameter identification with a finite-element model of the system.     

Comparison between models predicting the evolution of the electrical impedance with frequency

This paper explains and compares different models describing the evolution of the impedance of complex shaped conductors with low and with high frequencies. Indeed, at low frequencies, the evolution of the impedance of conductors with the frequency is negligible whereas at high frequencies, it is quite significant and generally well‐known. Parameterized models, based on the diffusion equation or on phenomenological approaches, are applied on complex shaped conductors, with a variable or not section. The parameters are found by identification with finite elements models. It is shown that simple phenomenological approaches gives accurate models with few parameters. Copyright © 2010 John Wiley & Sons, Ltd.