Analysis of losses due to rotor vibrations in a high-T-c superconducting flywheel system

摘要

The loss mechanisms associated with the combined effects of magnetic unbalance and hysteretic damping in a superconducting flywheel system have been modelled under the assumption that the dynamic characteristics of the bearing can be approximated by a linear, elastic isotropic spring with structural damping. The theoretical rundown equation of motion of such systems has been obtained by a Lagrangian approach, neglecting the effects of angular acceleration. The unknown parameters of the theoretical model have been determined by two different identification procedures starting from experimental time versus rotational speed curves obtained during rundown tests performed on a plastic flywheel with embedded permanent magnet, suspended on a high T-c superconducting stator. In addition to magnetic friction and eddy current losses, the hysteretic nature of the superconducting magnetic bearing gives a significant contribution to the overall losses. Accordingly, the efficiency of the system can be increased by minimizing the unbalance of the rotor. (C) 1998 Academic Press Limited. [References: 18]