Modeling of Electrodynamic Bearings

Abstract

A new model of electrodynamic bearings is presented in this paper. The model takes into account the R-L dynamics of the eddy currents on which this type of bearing is based, making it valid for both quasistatic and dynamic analyses. In the quasistatic case, the model is used to obtain the force generated by an off-centered shaft rotating at a fixed speed in a constant magnetic field. The model is then used to analyze the dynamic stability of a Jeffcott rotor supported by electrodynamic bearings. The essential role played by nonrotating damping in ensuring a stable operating range to the rotor is studied by means of root loci. Comparison with literature results is finally used to validate the model.

Unified modelling of passive homopolar and heteropolar electrodynamic bearings

“…It has been demonstrated both analytically [1,9,16,19] and experimentally [9] that the introduction of nonrotating damping directly between rotor and stator is a possible solution for this problem. Another possibility is the introduction of damping between two nonrotating parts, namely the stator of the electrodynamic bearing and the casing of the machine [20].…”

“…The lack of models describing the electromechanical coupling introduced by an EDB between the motion of the rotating conductor and the stator was addressed by the authors [19]. In that work, an electromechanical model capable of taking into account both the quasistatic and dynamic behaviour of the eddy currents is introduced wherein both the rotation and whirling of the rotor mass influence the dynamics of the eddy currents.…”

Fundamental considerations on introducing damping to passively magnetically stabilized rotor systems

“…Electrodynamic and superconducting bearings even introduce instability to the supercritical regime. 7 Thus, several approaches have been developed to damp passive magnetic bearing systems.…”

“…Additionally, passive magnetic bearing systems combine outstanding reliability with relatively low complexity of the bearing element (especially in comparison with active magnetic bearings). Passive stabilization can be achieved using superconducting materials, [1][2][3] electrodynamic effects, [4][5][6][7][8] or permanent magnetic bearings, [9][10][11][12][13] but the common problem is a lack of damping. Electrodynamic and superconducting bearings even introduce instability to the supercritical regime.…”

A Novel Flexible PCB Conductive Structure for Electrodynamic Bearings and Measurement in its Induced Voltage

“…The earliest application of electrodynamic bearings dates back to the 1980s and 1990s -used for flywheels [3][4][5][6][7][8][9][10][11][12][13][14][15] because electrodynamic bearings' features matched flywheels' requirements very well. Firstly, flywheels typically work at the state of high-speed rotation, and it is at such high rotation speed that electrodynamic bearings can realize levitation; secondly, stiffness and rotation precision are not core requirements of flywheels, which are also drawbacks of electrodynamic bearings.…”