Research On Vibration Characteristic Of Bulk High Temperature Superconductor Above Permanent Magnet Guideway

The vibration of high temperature superconducting (HTS) maglev vehicle system is excited due to the disturbance of surroundings in the actual operation. When the vibration of the HTS maglev system is excited, the applied magnetic field of high temperature superconductor (HTSC) changes simultaneously, and enhances the movement of magnetic flux, finally gives rise to energy loss of the HTSC. The energy loss will result in the change of levitation state and performance degradation of maglev system, deteriorate the stationarity of maglev vehicle, and even endanger the safety of running vehicle. With the increase in HTS maglev vehicle speed, effects of vibration between the HTSC and the permanent magnet guideway (PMG) obviously intensify and the perniciousness of vibration more highlights. Therefore, it is necessary to systematically investigate the vibration characteristic of HTS maglev system, make clear characteristics of interaction between the HTSC and PMG, and the law of function of influence factor.The vibration characteristics of free levitation and running HTSC, and the law of function of related influence factor are studied comprehensively by means of experimental measurement and numerical simulation in this dissertation.Under research of experimental measurement, firstly the change rule of the dynamic parameters and levitation height are firstly studied under different loads conditions (vertical movement, lateral movement, longitudinal unbalance loading and lateral unbalance loading) based on the scaled HTS maglev vehcle. Then, an HTS maglev dynamic test system developed in ASCLab is used to simulate the running situation of the HTS maglev vehicle, the vibration response characteristics are investigated at different running speeds of PMG, the experimental conditions include field cooling height, running mode and running time, and so on.Under research of numerical simulation, after analysing the interaction law of the HTS maglev vibration system, the HTS vibration differential equation, the three dimensional (3D) electromagnetic governing equations of the HTSC, the thermal governing equation of the HTSC and the 3D analytical model of the PMG are established respectively. A current vector potential is introduced to establish the 3D electromagnetic governing equations on the basis on the anisotropy of the HTSC. Based on above four governing equations, a 3D coupled electromagnetic-thermo-mechanical model of the HTS maglev vibration system is established. The thesis confirms the validity of the above mentioned theoretical model under four different movement types such as:vertical movement, lateral movement, longitudinal movement and vertical vibration.Aiming at the free HTSC of HTS maglev system, the vibration characteristics of the HTSC applied vertical and lateral excitation under different operation conditions, material properties, geometries and temperature rise are firstly analyzed respectively. In the end, vertical and lateral resonance frequency of HTS maglev system is investigated respectively under different operating conditions and material properties.Aiming at the running HTSC at a constant speed of HTS maglev system, the vertical vibration characteristics of the HTSC under different aperture between adjace permanent magnets, the irregularity of PMG, operation conditions, material properties and temperature rise are firstly analyzed, and it is theoretically proved that pre-loading is an effective approach to reduce the levitation drift during vibration. These results will be the important scientific guidance for the design of the HTS maglev vehicle system.