Lateral restorable characteristics of the high-Tc superconducting maglev vehicle above the permanent magnet guideway

The lateral restorable characteristics of a translational symmetry high-T_c superconducting maglev system are investigated by measuring its resonant frequency (f_RF) after a lateral displacement. The difference between whether this lateral displacement is restorable, meaning elastic or inelastic, is determined by whether or not the maglev body returns to its original position after a lateral displacement. The maximum restorable lateral displacement (δ_MRLD) is determined by the sudden change of the f_RF vs. the maximum lateral displacement (δ_MLD) curve. The f_RF of the high-T_c superconducting maglev system with different field-cooling height (FCH) and working height (WH) was obtained from the frequency domain vibration curve which was measured by a vibration measurement system. The results showed that, the δ_MRLD was reduced when the WH was decreased. The maximum restorable guidance force (F_MRGF) was found to not always increase with the lowering of the WH for the same FCH. The lateral restorable stiffness (k_LRS) was always enhanced with the decrease of the WH. The decrease of the δ_MRLD with the WH is interpreted by the fact that, the tangential field component (ΔH) across the surface of the high-T_c superconductor (HTSC) is easier to exceed the J_cλ value (J_c is the critical current density and λ is the London penetration depth) when the WH is lowered, and this makes the trapped flux lines become more susceptible in escaping its pinning sites.