Investigation of HTS Racetrack Coil Without Turn-to-Turn Insulation for Superconducting Rotating Machines

Kim, Young-Gyun; Hahn, Seungyong; Kim, Kwang Lok; Kwon, Ohin; Lee, Haigun

doi:10.1109/tasc.2011.2181931

Cited by 68 publications

(22 citation statements)

References 7 publications

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“…The no-insulation (NI) winding technique [24] provides HTS coils with better thermal stability [25,26], higher current density [27,28], defect-irrelevance properties [29,30] and better mechanical integrity [31][32][33][34][35]. In recent years, the NI winding technique has facilitated quite a few breakthroughs in HTS magnet technology [28,36].…”

Section: Introductionmentioning

confidence: 99%

Study of the demagnetization behavior of no-insulation persistent-current mode HTS coils under external AC fields by 3D FEM simulation

Zhong,

Wu,

et al. 2024

Supercond. Sci. Technol.

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The no-insulation (NI) winding technique is promising to be applied in the persistent-current mode (PCM) operation of high-temperature superconducting (HTS) coils to provide those advantages. To apply the NI PCM coil, its demagnetization behaviour (i.e., decay of persistent DC current) by external AC field, which occurs in maglev trains, electric machines, and other dynamic magnet systems, is essential to be understood. For this purpose, a 3D FEM model, capturing the full electromagnetic properties of NI HTS coils, is established. This work has studied three kinds of AC fields, observing the impact of turn-to-turn contact resistivity on demagnetization rates, which is attributed to current distribution modulations. Under transverse AC field, the lower contact resistivity attracts more transport current to flow in the radial pathway to bypass the ‘dynamic resistance’ generated in the superconductor, leading to slower demagnetization. Under axial AC field, the demagnetization rate exhibits a non-monotonic relation with the contact resistivity: (1) the initial decrease of contact resistivity leads to concentration of induced AC current on the outer turns, which accelerates the demagnetization; (2) the further decrease of contact resistivity makes the current smartly redistribute to avoid to flow through the loss-concentrated outer turns, thus slowing down the demagnetization. Under the rotating DC field, a hybrid of the transverse and axial fields, the impact of contact resistivity on the demagnetization rate exhibits combined characteristics of the transverse and axial components. Besides, quantitative prediction on the demagnetization rate of NI PCM coil under external AC field is instructive for practical designs and operations, which is tried by this 3D FEM model, and a comparison with experimental result is conducted.

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Section: Introductionmentioning

confidence: 99%

Study of the demagnetization behavior of no-insulation persistent-current mode HTS coils under external AC fields by 3D FEM simulation

Zhong,

Wu,

et al. 2024

Supercond. Sci. Technol.

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“…Large scale HTS applications [1][2][3], such as HTS transformer, HTS magnet, HTS rotating machine, have been reported. Due to the J c (B,θ) relation in HTS tape, current capacity of coils is subject to the magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Characterization analysis on performance of YBaCuO coils induced by steady-state current

Liu

Song

et al. 2015

2015 IEEE International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD)

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The steady-state current (dc) characterization of high temperature superconducting (HTS) coils is a key role of its performance assessing. Due to the orientation dependence of the critical current density, J c (B,θ), the magnetic field distribution of a given HTS coils depends on the shape of coils as well as the consistent tape applied. In the present paper, the dc characterizations of two HTS coils with same turns but different architectures are modeled by using the 3D finite element method. It is revealed that the engineering critical currents of both coils are subject to the end parts of coils. As the dc current is applied, the central magnetic field emerged is similar for both of them. As the dc current increases, the generated voltage for Coil A with an high aspect ratio of height to outer radius, is much lower than that of Coil B with a squashed shape, implying that Coil A gives rise to a higher toleration for applied current, and then a better performance for potential magnet.

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“…For this reason, considerable research has been carried out on the protection of HTS magnets [9][10][11]. Recently, the use of an HTS magnet without the turn-to-turn insulation was proposed for the enhancement of a magnet's thermal and electrical stabilities owing to its auto-protective effect, through which the excessive heat and current flow generated by local quenching could be automatically diverted through the turn-to-turn contacts [3,[12][13][14]. Thus, this no-insulation winding technique may facilitate protection-free HTS application.…”

Section: Introductionmentioning

confidence: 99%

Screening current-induced field in non-insulated GdBCO pancake coil

Yang

Kim

Choi

et al. 2013

Supercond. Sci. Technol.

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In this study, empirical and numerical analyses on the screening current-induced field (SCIF) characteristics of a non-insulated (NI) GdBCO-coated conductor single-pancake coil were conducted. Charge and discharge tests were carried out to induce an SCIF in the NI test coil. The SCIF in the NI coil was identified by comparison between the measured and calculated magnetic fields. The experimental results exhibit an increase of the SCIF with increasing an operating current, as well as a logarithmic decay of the SCIF as a function of time. Moreover, the SCIF was not affected by the slow discharge of the NI coil. The estimation of the SCIF based on the critical-state model in a thin film using the finite element method was in fairly good agreement with the experimental results.

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Investigation of HTS Racetrack Coil Without Turn-to-Turn Insulation for Superconducting Rotating Machines

Cited by 68 publications

References 7 publications

Study of the demagnetization behavior of no-insulation persistent-current mode HTS coils under external AC fields by 3D FEM simulation

Study of the demagnetization behavior of no-insulation persistent-current mode HTS coils under external AC fields by 3D FEM simulation

Characterization analysis on performance of YBaCuO coils induced by steady-state current

Screening current-induced field in non-insulated GdBCO pancake coil

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