Charging Behavior in No-Insulation REBCO Pancake Coils

Wang, Xudong; Wang, Tao; Nakada, Erika; Ishiyama, Atsushi; Itoh, Ryusei; Noguchi, So

doi:10.1109/tasc.2014.2365623

Cited by 38 publications

(24 citation statements)

References 7 publications

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“…Also as reported in [4], it is suggested that the NI coil can be used as a low-pass filter. Charging, discharging, and overcurrent behaviors of the NI coil are investigated by using a comprehensive equivalent NI coil circuit grid model [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

An Experimental Investigation of the Transient Response of HTS Non-insulation Coil

Zhang

Kim

et al. 2016

J Supercond Nov Magn

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A single pancake coil without turn-to-turn insulation was tested in this paper to investigate the transient responses under different situations. We performed charging and discharging test, AC current test, and regional quench emulation test on the non-insulated (NI) coil. The experimental test results show a significant time delay for charging and discharging characteristics of NI coil and can be validated by a simple proposed equivalent electrical circuit. Under the AC operating current, the NI coil can bypass nearly all the AC current from the coil spiral path to the radial path such that it is not possible for NI coil to store or be affected by the AC magnet field. Additionally, while carrying AC current, the AC loss dissipation of NI coil is inversely proportional to the frequency of the AC operating current. When a regional quench occurs, the NI coil can bypass the current in the regional quench zone to avoid further temperature accumulated and protect the NI coil itself.

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Section: Introductionmentioning

confidence: 99%

An Experimental Investigation of the Transient Response of HTS Non-insulation Coil

Zhang

Kim

et al. 2016

J Supercond Nov Magn

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“…The reference [4] showed the turn-to-turn contact resistivity, 70 µΩ·cm 2 . However, its value includes the copper stabilizer and Hastelloy substrate resistivities, so it is termed "coil-radial contact resistivity" in this paper.…”

Section: B Coil-radial Contact Resistivitymentioning

confidence: 99%

“…Additionally, owing to no insulation material, the current density can be increased. However, the drawback to the NI winding technique is the charging delay [4]. So far, to confirm the effectiveness of the NI winding technique, some current flow simulations in a pancake coil have been performed using the simple equivalent electrical circuit model [5], [6] or the partial element equivalent circuit (PEEC) model [7].…”

Section: Introductionmentioning

confidence: 99%

“…So far, to confirm the effectiveness of the NI winding technique, some current flow simulations in a pancake coil have been performed using the simple equivalent electrical circuit model [5], [6] or the partial element equivalent circuit (PEEC) model [7]. Through these simulations [4]- [6] and experiments [1]- [3], [7] it was Automatically generated dates of receipt and acceptance will be placed here; authors do not produce these dates. This work was supported in part by the Grant-in-Aid for Scientific Research (A) (Grant Number 26249036).…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Current Flow Between Turns of NI REBCO Pancake Coil by 2-D Finite-Element Method

Noguchi

Monma

Igarashi

et al. 2016

IEEE Trans. Appl. Supercond.

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Abstract-TheNo-Insulation (NI) winding technique for NI REBCO pancake coil is expected to improve the dynamic and thermal stability and to enhance the current density. The investigations of the electromagnetic and thermal behaviors are important for the development of NI REBCO coils. Many stability investigations of the NI REBCO coil itself have been carried out by experiments and simulations. However, the detailed behavior of the bypass current between turns has been not shown yet. Although the contact resistivity was obtained through the priori experiment, it included the resistivity of not only contact surface but also the components, i.e., the copper stabilizer and the Hastelloy substrate, of REBCO tape. To investigate the detailed bypass current behavior in this paper, the true contact surface resistivity is taken into account in the simulation. The bypass current on the cross section of NI REBCO tape is simulated using the 2-D FEM. From the simulation results, the influence of the coil-radial resistivity between turns on the turn-to-turn contact surface resistivity is clarified. In addition, the heat loss is also reported, and a simple equivalent circuit of the turn-to-turn contact is proposed.

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“…A few simulation methods for NI REBCO pancake coils have been developed for clarification of the high stability mechanism [2], [6]. The simple equivalent circuit model is a facile analysis method [2]; however, the current behavior inside the NI REBCO pancake coil is not considered.…”

Section: Introduction He No-insulation (Ni)mentioning

confidence: 99%

Experiment and Simulation of Impregnated No-Insulation REBCO Pancake Coil

Noguchi

Monma

Iwai

et al. 2016

IEEE Trans. Appl. Supercond.

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Abstract-It is important to investigate the stability and behavior of an epoxy-resin-impregnated no-insulation (NI) REBCO pancake coil in order to implement high-field applications, such as ultra-high-field magnetic resonance imaging. We have performed sudden discharging and overcurrent tests for the impregnated NI REBCO pancake coil. From the discharging test, the contact resistivity is estimated, and it changes depending on the initial current. From the overcurrent test, the high thermal stability of the impregnated NI REBCO pancake coil is confirmed. The REBCO pancake coil is charged up to 67 A though the critical current is only 46 A, and no degradation has been found.To investigate in detail the electromagnetic behavior of an impregnated NI REBCO pancake coil, the simulation is performed by means of the partial element equivalent circuit (PEEC) model. In the sudden discharging test, the simulation results for the case of lower initial current are in good agreement with the experimental data. As can be inferred from the simulation results, the current drastically decreases from the inside of the impregnated NI REBCO pancake coil. The result of the overcurrent simulation is almost identical to the experimental one. However, since the contact resistivity is presumed to be constant in the simulation, the difference is observed in the high current region.

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Charging Behavior in No-Insulation REBCO Pancake Coils

Cited by 38 publications

References 7 publications

An Experimental Investigation of the Transient Response of HTS Non-insulation Coil

An Experimental Investigation of the Transient Response of HTS Non-insulation Coil

Investigation of Current Flow Between Turns of NI REBCO Pancake Coil by 2-D Finite-Element Method

Experiment and Simulation of Impregnated No-Insulation REBCO Pancake Coil

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