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

Abstract

Recently, the application of high-Tc 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.

Modeling of High-Tc Superconducting Bulk using Different Jc–T Relationships over Dynamic Permanent Magnet Guideway

“…This is because the flux inside the HTS bulk under higher vibration frequency is more intense. Other studies in the literature [15,16] have concluded that the levitation force is a little higher when not considering the thermal effect than when accounting for the thermal effect, because the attenuation caused by thermal loss is not considered. From this point of view, under the experimental vibration condition, the force attenuation without the thermal effect is a little smaller than the case considering the thermal effect, in which J c retains some mathematic relationships with temperature T during the calculations.…”

“…Using this linear formula, Tixador et al [14] calculated the current distribution and AC losses of the YBCO slab. In recent years, Ye [15] and Huang [16] studied the dynamic thermal effect of the HTS Maglev system using YBaCuO bulks by the linear J c –T relation.…”

Impact of Strain and Field Ramp Path on Thermomagnetic Instabilities in Composite Nb3sn Wires with Multi-Filaments Inside the Superconducting Coil

“…The maximal strain of our Nb3Sn superconducting coil with an applied current of 700 A is about 0.9% which causes a severe decrease in critical current. Although the sensitivities of thermomagnetic instabilities to various electromagnetic and thermal parameters have been studied in experiments and numerical simulations [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61], the effects of strain, filamentary size, and the field ramp functional form on the flux jump are still unclear. These parameters play a crucial role in the flux jump, so it is essential to reveal their influences on the superconducting magnets during the operation.…”

Comparative study between electromagnet and permanent magnet rails for HTS maglev

“…Since the discovery of high temperature superconducting (HTS) phenomenon, HTS materials have attracted extensive interest in superconducting maglev studies [1][2][3][4][5][6][7][8][9] due to their unique properties. The interaction between an HTS bulk and a magnet guideway can produce both vertical levitation force and lateral guidance force, which is the unique feature of HTS maglev [10].…”