Investigation of HTS Tape Stacks for Levitation Applications

This work presents simulation studies on superconducting jointless loops known as double crossed loop coils, made from partially slit and stacked REBCO tape segments. The objective is to investigate design parameters for a novel magnetic bearing application, trying to increase the (levitation force)/(tape length) ratio. The adopted simulation strategy is to model the tapes as one-dimensional current sheets with the current density written as integral equations solved by finite elements. For this recently developed type of coil, each current path must be modeled, thus every tape should be represented in the simulation, as shall be discussed. The results demonstrate how the coils’ performance varies non-linearly to the geometric parameters and that stacking the maximum number of tapes is not the only way to increase the levitation force. Their force curves also do not show the same behavior as expected for bulk ones, and an analysis is performed to relate it to the critical current sensitivity to the magnetic field. A more detailed investigation explains this behavior from the induced currents’ point of view in every loop of the stack. Comparisons between the simulation data and prototype tests prove that the chosen model can satisfactorily reproduce the measurements.

Section: Implementation In Comsolmentioning

confidence: 99%

“…These aspects make them possible substitutes for YBCO bulk materials in large scale applications. Some research groups have already started developing this topic with stacked REBCO tapes for both linear [3][4][5][6][7][8][9] and rotational [10,11] magnetic bearings.…”

Section: Introductionmentioning

confidence: 99%

Simulations of REBCO tape jointless double crossed loop coils with an integral equations method

Martins

Sass

Andrade

2019

“…The development of the production technology for REBCO-coated conductor tapes (so called CC-tapes) maked it possible to use them as an alternative to bulk superconductors [7]. The presence of a metal substrate provides a higher thermal and mechanical stability, while the levitation characteristics of tape stacks are comparable to bulk HTS [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, a number of studies on the use of CC-tapes stacks in levitation systems have been carried out. At the moment, a variety of researches are performed in the fields of creating levitation suspensions [7,[13][14][15][16][17] and motors [18], investigating the influence of the number and configuration of elements in the stack on the vertical [19] and lateral [8,9] components of the levitation force, verifying the effect of CC-tape characteristics on the levitation force [20]. However, there are still few studies on bearings based on CC-tapes.…”

Section: Introductionmentioning

confidence: 99%

Scalable superconductive magnetic bearing based on non-closed CC tapes windings

Osipov

Anishenko

Starikovskii

et al. 2021

A new type of scalable high-temperature superconducting magnetic bearing is proposed. The bearing is based on the multilayer open windings made of coated conductor-tapes (CC-tapes). To demonstrate the possibility of manufacturing such a bearing construction we have built a working prototype and studied its characteristics. The manufactured model of bearing includes a stator, consisting of three multilayer rings (CC-tapes pancake coils) of 12 mm CC-tape and a composite rotor consisting of three rings of permanent magnets, each composed of 16 NdFeB 10 × 10 mm permanent magnets. We showed a contactless levitation of rotor relative to stator, as well as rotation of rotor and we measured load curves, namely the dependence of the rotor displacement on restoring force for axial and radial loads. Numerical simulation of bearing load characteristics has been carried out by the finite element method in the Comsol Multiphysics software. The calculation results are in a good agreement with the experimental data.

“…The use of REBCO tapes (so called coated conductors, CC-tapes) overcomes the limitations of bulk HTSs. A detailed comparison of the advantages and disadvantages of tapes stacks and bulk HTSs in levitation applications is given in [10].…”

Section: Introductionmentioning

confidence: 99%

The influence of temperature on levitation properties of CC-tape stacks

Osipov

Starikovskii

Anishenko

et al. 2021

This article presents the study of the temperature effect on the levitation characteristics of stacks of CC-tapes from various manufacturers SuperOx, Theva and Sunam. Tapes differ in the values of the critical current density, architecture, and parameters of the metal substrate. Stacks of tapes were assembled from 12 by 12 mm square pieces of CC-tape. The number of elements in the stacks varied from 5 to 70. The dependences of the levitation force Fz (the vertical component of the force in the system permanent magnet—HTSC stack) on temperature were obtained both in zero field cooling (ZFC) and in field cooling (FC) modes. The measurements were carried out in the temperature range of 32–100 K. We have established that, down to the minimum operating temperatures, a decrease in temperature leads to a continuous increase in levitation force in ZFC mode. In FC mode, the Fz value tends to saturate after the initial increase in force. Cooling below the boiling point of liquid nitrogen up to 65 K gives a levitation force gain of 5%–10%. At the same time, cooling to 35 K gives an increase in levitation force by 7%–23%. It was found that an increase in the number of elements in the stack from 5 to 70 leads to an increase in the levitation force with a tendency to saturation for all temperatures studied. Excellent agreement between the experimental and calculated dependences of the levitation force on temperature and the number of elements in the stacks is demonstrated. Calculations show that for Sunam tapes, 90% of the levitation force is achieved with a stack thickness of 100 tapes at the boiling point of liquid nitrogen, and with 70 tapes at lower temperatures. The distributions of the magnetic field during the approach/removal of magnets, as well as the distribution of the trapped magnetic flux at different temperatures and numbers of elements in the stacks are modelled.