Experiment and simulation of superconducting magnetic levitation with REBCO coated conductor stacks

Abstract

Three superconducting stacks made of 120 REBCO coated conductor tapes were each fabricated and assembled to obtain several REBCO modules. Their levitation responses over two different permanent magnet (PM) guideways were investigated by experiment and finite element simulation. For the experiment, a test rig was developed that can measure the force in the three directions for any given relative movement between the REBCO stacks and the PM guideway. For the finite element simulation, a 2D H-formulation was adopted. To treat the high aspect ratio of REBCO tapes, an anisotropic homogenization technique was used. The agreement between the measurements and the simulations is good, thus validating the modeling methodology. It was observed from the experiment and simulation results that the perpendicular field contributes to the levitation force whereas the parallel field is responsible for the guidance force, as a result of the existence of anisotropy on the local magnetic stimulation. Based on that, promising REBCO modules including both longitudinal and transverse arrangements of REBCO stacks were proposed and tested, in terms of providing a significant levitation force with the lateral stability preserved. Moreover, a pre-load process able to suppress the relaxation of the levitation force was put forward. To conclude, this study outlines explicit principles to obtain an appropriate layout of coated conductor stacks that could be effective for practical magnetic levitation operation.

Modelling the Frequency Dependence of the Open-Circuit Voltage of a High-T c Superconducting Dynamo

“…The segregated model, implemented in COMSOL Multiphysics 5.4, consists of a magnetostatic PM model and a time-dependent H-formulation HTS wire model. The former is coupled unidirectionally to the latter using electromagnetic boundary conditions and a rotation operator to mimic the movement of the PM [20,34,35], as shown in Fig. 2.…”

“…On the outer boundary of the H-formulation model, the sum of the applied field, H ext , and the self-field, H self , is applied as a Dirichlet boundary condition. H ext is obtained by rotating the field of a static permanent magnet [6] and H self , created by the supercurrent flowing in the HTS wire, is obtained at each time step by numerical integration of the 2D Biot-Savart law over the HTS wire subdomain [20,35].…”

Modeling cross-field demagnetization of superconducting stacks and bulks for up to 100 tapes and 2 million cycles

“…The main benefits of superconducting stacks or bulks over coils are the compactness of size, sturdy material and geometry, and exclusion of current leads which accounts for substantial reduction of heat load 25 . In addition, stacks of tapes and bulks can also generate the levitation force in levitating trains and flyweels, see 26 – 28 for bulks and 29 – 32 for stacks. Finally, stacks of tapes can also enable compact magnets, such as those for Nuclear Magnetic Resonance 33 .…”

Electromagnetic and Levitation Characteristics of a High-Temperature Superconducting Bulk Above an Electromagnet Guideway

“…There have been many developments related to maglev technology starting from fundamental studies on HTS bulks above PMs [10]. To assess the performance of an HTS-PM maglev system, the levitation characteristics of such systems, including magnetic field distributions generated by various PM arrangements [11][12][13], levitation force and guidance force [14][15][16][17][18][19], and the stability [20][21][22][23] have been investigated in numerous studies. These characteristics are strongly related to the electromagnetic interactions between the HTS and the PM.…”