Investigation of electrical characteristics of no-insulation coil wound with surface-processed HTS tape

Jeon, Hye‐Seon; Lee, Woo Seung; Kim, Jinsub; Baek, Geonwoo; Jeon, Sangsu; Yoon, Yong Soo; Ko, Tae Kuk

doi:10.1016/j.physc.2017.06.003

Cited by 4 publications

(3 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2-3 s with 90 µΩ cm 2 ); on the contrary, when the contact resistivity is smaller, the slower transition in the field response has better accuracy (after 8 s with 30 µΩ cm 2 ); and the larger the contact resistivity, the faster the field changes in simulation. As aforementioned [15][16][17], the contact resistivity changes with surface roughness and tolerance, load cycles, thermal cycles, stress, and temperature etc. Moreover, Kim et al [28] observed that the turn-toturn contact within the coil was enhanced with larger amplitude of current due to the increased Lorentz force when a NI coil was ramped up with the same ramping rates.…”

Section: Analysis Of Sudden-discharge and Charge Processmentioning

confidence: 89%

“…Moreover, the contact resistivity changes a lot with different load cycles, thermal cycles, and temperature [15,16]. Even when different samples are handled in the same way, the absolute values of contact resistivity are different probably due to the different thickness tolerance and surface roughness [17]. Because of these highly impacting factors, it is quite difficult to estimate the accurate contact resistivity after winding the NI coil based on the contact resistivity measurements from short samples.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study of contact resistivity of a no-insulation superconducting coil

Liu

Gyuráki

et al. 2021

Supercond. Sci. Technol.

View full text Add to dashboard Cite

Previous studies of test coils have demonstrated the high thermal and electrical stability of no-insulation (NI) high temperature superconducting (HTS) coils thanks to the presence of turn-to-turn current paths. These turn-to-turn current paths in a NI coil are significantly influenced by the contact resistivity. In practice, it is very challenging to measure the contact resistivity of a NI coil by direct experiments of short samples, since the contact resistivity of superconducting tapes is influenced by surface roughness and tolerance, stress, temperature etc. A proper simulation model is needed to investigate the contact resistivity of the NI coils with dedicated experiments. Hence, in this paper a distributed circuit model is employed. This model, implemented in Matlab 2018a, considers the local contact resistivity, self and mutual inductance, and HTS resistance, which depends on the supplied current, magnetic field and temperature. To validate the model, experimental results from literature, including sudden discharge, and charge–discharge processes, are employed and the results from simulations are consistent with experimental results. Then the model is used to investigate the equivalent contact resistivity of a 157-turn NI coil. Through the comparison of simulated and experimental results, it is found that the contact resistivity of the NI coil has an inhomogeneous distribution. When the current changes with different speeds, ramping rates or frequency, a different number of turn-to-turn contacts carries radial current. Since the turn-to-turn contacts have different contact resistivity, the equivalent contact resistivity calculated from sudden discharge cannot be used in simulations to reproduce all the experimental data.

show abstract

Section: Analysis Of Sudden-discharge and Charge Processmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Study of contact resistivity of a no-insulation superconducting coil

Liu

Gyuráki

et al. 2021

Supercond. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…where L coil is the coil inductance. The equivalent contact resistivity ρ c of the tested PWNI HTS coil can be calculated using the following equation [51]:…”

Section: Sudden Discharging Testmentioning

confidence: 99%

Non-uniform current distribution in parallel-wound no-insulation high-temperature superconductor coil during ramping and fast discharging operations

Fu,

Wang,

Peng

et al. 2023

Supercond. Sci. Technol.

View full text Add to dashboard Cite

A parallel-wound no-insulation (PWNI) high-temperature superconductor (HTS) coil is a kind of pancake-shaped no-insulation (NI) coil wound with parallel-stacked HTS tapes, which combines the characteristics of a NI coil and non-twisted stacked-tape cable. It shows a significant advantage in accelerating the ramping response compared with traditional NI HTS coils wound by a single tape, and is a promising alternative for large-scale high-field magnets. The stacked cable approach can lead to current redistribution between parallel tapes during ramping operations. It couples with the turn-to-turn current redistribution and leads to a much more complicated current redistribution inside the PWNI coil, the mechanism of which remains unclear so far. The aim of this work is to investigate electromagnetic behavior of a PWNI HTS coil in ramping and fast discharging process. A simulation model was developed by integrating an equivalent circuit network model and an improved T–A model. A three-tape PWNI coil and its insulated counterpart were wound and tested, and this model was validated by charging and discharging tests. Results show that there is a significant non-uniform current distribution on parallel tapes in the same turn during ramping operations and the maximum azimuthal current (transport current) can be 2.26 times the minimum one in the three-tape PWNI coil in this study. Meanwhile, the radial current shows a considerable accumulation in the tape near turn-to-turn contacts and the radial current through the turn-to-turn contacts can be 4.16 times of that the flow through tape-to-tape contacts (parallel tapes) in the same turn. During the fast discharging process, a significant coupling current is generated in the PWNI coil, leading to a large opposite transport current in local areas; the amplitude of variation of this can be 4.66 times the initial operating current. The radial current shows a similar distribution but opposite direction to that during ramping, and its amplitude is two orders of magnitude higher. These results provide practical guidelines for the design of large-scale high-field HTS magnets.

show abstract

R&D of No-Insulation HTS Magnets Using 2G Wires in a Prototype for Maglev Applications

Dong

Huang

et al. 2019

IEEE Trans. Appl. Supercond.

View full text Add to dashboard Cite

Investigation of electrical characteristics of no-insulation coil wound with surface-processed HTS tape

Cited by 4 publications

References 4 publications

Study of contact resistivity of a no-insulation superconducting coil

Study of contact resistivity of a no-insulation superconducting coil

Non-uniform current distribution in parallel-wound no-insulation high-temperature superconductor coil during ramping and fast discharging operations

R&D of No-Insulation HTS Magnets Using 2G Wires in a Prototype for Maglev Applications

Contact Info

Product

Resources

About