Magnetic Field Saturation of Non-Insulation High-Temperature Superconducting Coils during Overcurrent

Wu, Wei; Gao, Yusong; Jin, Zhijian

doi:10.3390/electronics10222789

Cited by 2 publications

(2 citation statements)

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“…The material-related parameters, k, B c , I c0 (J c0 equals to I c0 divided by the modeled cross-sectional area of single HTS tape) and α measured from the short GdBCO sample from the Shanghai Superconductor are consistent with [48]. A mapped mesh is used for the superconductor with 1 element along the thickness and 50 elements along the width, and a free triangular mesh is used for the air domain.…”

Section: H-formulation Modelmentioning

confidence: 99%

“…First, B AC, ϕ , which is neglected in the simulation, has an influence on the critical current of the HTS tape [34,54,55]. Second, the field dependence of the critical current, i.e., the I c (B, θ) characteristics, set in the simulation was measured in 2021 for the HTS tapes manufactured in that year [48]; by contrast, the experimental coil was wound using the same type of HTS tape but was manufactured in 2022. It has been recognized that the I c (B, θ) characteristics, even for the same type of HTS tapes, may vary a lot among different manufacturing batches [56,57].…”

Section: Simulation Analysismentioning

confidence: 99%

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Time-variant magnetic field, voltage, and loss of no-insulation (NI) HTS magnet induced by dynamic resistance generation from external AC fields

Zhong

et al. 2023

Supercond. Sci. Technol.

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High-temperature superconducting (HTS) coils serving as DC magnets can be operated under non-negligible AC fields, like in synchronous machines of maglev trains and wind turbines. In these conditions, dynamic resistance generates in HTS tapes, causing redistribution/bypassing of the transport current inside the no-insulation (NI) coil and its unique operational features. This issue was studied by experiments on an NI coil with DC current supply put into external AC fields. Due to the current redistribution induced by dynamic resistance, the central magnetic field and voltage of the NI magnet initially undergo various transient processes, and eventually exhibit a stable central magnetic field reduction and a DC voltage. These time evolutions have implications for a time-varying torque and loss of an HTS machine. These time evolutions are strongly affected by the contact resistivity distribution, and whether it is the first time of the NI magnet being exposed to the AC field, showing several qualitatively different waveforms (e.g., some are even non-monotonic with time). The magnitudes of the stable central field reductions, and their observed linear correlation with the DC voltages are found to be decided by the local contact resistivity of the innermost and outermost several turns. It is also noted that the non-insulated turn-to-turn contact help lessening the loss induced by the dynamic resistance. A numerical model is established to analyse/explain those experimental results by observing the microscopic current distribution. Two risks of quench are noticed: (i) azimuthal current of the middle part turns increases as the AC field is applied; (ii) a concentration of radial current is observed near the terminals of the NI coil.

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Section: H-formulation Modelmentioning

confidence: 99%