Dynamic simulations of actual superconducting maglev systems considering thermal and rotational effects

Recently, the application of high-T _c superconductors with longitudinal geometry to linear bearings and transportation devices has reached a higher stage of development. For these maglev systems, static stability has already been established; but dynamic stability is still under investigation, since these systems have multiple degrees of freedom and their dynamics are coupled with intricate superconducting phenomena. In this paper, in terms of Newton's second law, the thermal diffusion equation, and Maxwell's equations together with a nonlinear power-law constitutive relation, we build a two-dimensional thermal-electromagnetic coupling model to study the dynamics of actual maglev systems composed of a superconductor and a guideway formed by conventional and Halbach arrays of permanent magnets. We assume that the zero-field-cooled superconductor slowly descends to a working height and then its dynamic motion is triggered by an external disturbance or excitation. The results show that when the superconductor has a disturbance-induced initial translational or angular velocity at the working position, vibration and drift phenomena occur simultaneously in the lateral, vertical and rotational directions, and the local temperature rise will aggravate the center of the drift of vibration but will shorten the levitation stabilization time. Lowering the ambient temperature is effective at alleviating the levitation drift. However, a balance between the levitation force and lateral stability should be noted because an excessively low ambient temperature may lead to instability. Additionally, a resonance phenomenon will occur under an external excitation if its frequency is too close to the system's resonance frequency, which causes a dramatic rise in local temperature and a further large drift for the center of vibration.