論文 - 川越　明史

A. Kawagoe, M. Yoshida, S. Ando, S. Miura, H. Miyazaki, and M. Iwakuma .  Current Sharing in Parallel Conductors Using Bi-2223 Tapes in Perpendicular Magnetic Fields .  IEEE Transactions on Applied Superconductivity35 ( 5 ) 6400205   2025年8月査読

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

Fully superconducting synchronous motors are very interesting for mobile applications such as aviation, thanks to their high output power density (kW&#x002F;kg). In order to obtain a large current capacity, multi-strand parallel conductors are usually used in armature coils but parallel conductors without transposition present non-uniform current sharing. In this manuscript, current sharing properties among three REBa₂Cu₃O<italic>_y</italic> parallel tapes with&#x002F;without a transposition in three-phase armature coil conditions, were investigated experimentally and analytically. The sample coils were prepared under the three-phase arrangement of armature coils for a two-pole rotating machine, and its branch currents were evaluated by Rogowski coils by applying AC transport current in liquid nitrogen at 77 K. We demonstrated that the introduction of the transposition was also an effective way to control the current sharing in rotating magnetic fields generated by the three-phase armature coils as well as single-phase situations. In addition, the influence of other phase armature coils on the current sharing was discussed via analytical calculations.

DOI： 10.1109/TASC.2024.3522074

Scopus

Kei Shiohara, M. Sato, Y. Takahashi, K. Adachi, Akifumi Kawagoe, Teruo Izumi, Masataka Iwakuma .  Stacked Superconducting Cables With Coated Conductors Using New Corrugated Tubes for Electric Propulsion Systems for Aircraft .  IEEE Transactions on Applied Superconductivity35 ( 5 ) 3600704   2025年8月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

Fully superconducting synchronous motors are very interesting for mobile applications such as aviation, thanks to their high output power density (kW&#x002F;kg). In order to obtain a large current capacity, multi-strand parallel conductors are usually used in armature coils but parallel conductors without transposition present non-uniform current sharing. In this manuscript, current sharing properties among three REBa₂Cu₃O<italic>_y</italic> parallel tapes with&#x002F;without a transposition in three-phase armature coil conditions, were investigated experimentally and analytically. The sample coils were prepared under the three-phase arrangement of armature coils for a two-pole rotating machine, and its branch currents were evaluated by Rogowski coils by applying AC transport current in liquid nitrogen at 77 K. We demonstrated that the introduction of the transposition was also an effective way to control the current sharing in rotating magnetic fields generated by the three-phase armature coils as well as single-phase situations. In addition, the influence of other phase armature coils on the current sharing was discussed via analytical calculations.

DOI： 10.1109/TASC.2025.3538574

Scopus

H. Miyazaki, M. Iwakuma, Y. Emori, R. Konishi, K. Yoshida, S. Sato, H. Sasa, S. Miura, I. Sagara, Y. Suzuki, M. Konno, H. Hirai, A. Kawagoe, T. Izumi .  Performance Testing of 400 kW-Rated REBCO Superconducting Synchronous Machine in Low-Temperature and Low-Pressure Environments .  IEEE Transactions on Applied Superconductivity35 ( 5 ) 5201305   2025年8月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

Fully superconducting synchronous motors are very interesting for mobile applications such as aviation, thanks to their high output power density (kW&#x002F;kg). In order to obtain a large current capacity, multi-strand parallel conductors are usually used in armature coils but parallel conductors without transposition present non-uniform current sharing. In this manuscript, current sharing properties among three REBa₂Cu₃O<italic>_y</italic> parallel tapes with&#x002F;without a transposition in three-phase armature coil conditions, were investigated experimentally and analytically. The sample coils were prepared under the three-phase arrangement of armature coils for a two-pole rotating machine, and its branch currents were evaluated by Rogowski coils by applying AC transport current in liquid nitrogen at 77 K. We demonstrated that the introduction of the transposition was also an effective way to control the current sharing in rotating magnetic fields generated by the three-phase armature coils as well as single-phase situations. In addition, the influence of other phase armature coils on the current sharing was discussed via analytical calculations.

DOI： 10.1109/TASC.2025.3538574

Scopus

Goki Kawasaki, Kazuki Nakamura, Yudai Kimura, Tomohiro Inoue, Yohei Masuda, Shun Miura, Akifumi Kawagoe, Masataka Iwakuma .  Experimental Evaluation of Transposed Three-Parallel Conductors to Achieve Uniform Current in Armature Coils of Superconducting Motors .  IEEE Transactions on Applied Superconductivity35 ( 5 ) 5201205   2025年8月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

Fully superconducting synchronous motors are very interesting for mobile applications such as aviation, thanks to their high output power density (kW&#x002F;kg). In order to obtain a large current capacity, multi-strand parallel conductors are usually used in armature coils but parallel conductors without transposition present non-uniform current sharing. In this manuscript, current sharing properties among three REBa₂Cu₃O<italic>_y</italic> parallel tapes with&#x002F;without a transposition in three-phase armature coil conditions, were investigated experimentally and analytically. The sample coils were prepared under the three-phase arrangement of armature coils for a two-pole rotating machine, and its branch currents were evaluated by Rogowski coils by applying AC transport current in liquid nitrogen at 77 K. We demonstrated that the introduction of the transposition was also an effective way to control the current sharing in rotating magnetic fields generated by the three-phase armature coils as well as single-phase situations. In addition, the influence of other phase armature coils on the current sharing was discussed via analytical calculations.

DOI： 10.1109/TASC.2024.3520549

Scopus

Miura S., Nakamura K., Masuda Y., Kawasaki G., Miyazaki H., Kawagoe A., Sasa H., Yoshida K., Sato S., Iwakuma M. .  Current Sharing among Three-strand Parallel Conductors Composed of REBCO Tapes in Three-phase Armature Coil Conditions .  IEEE Transactions on Applied Superconductivity34 ( 5 ) 5200905   2024年8月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

Fully superconducting synchronous motors are very interesting for mobile applications such as aviation, thanks to their high output power density (kW&#x002F;kg). In order to obtain a large current capacity, multi-strand parallel conductors are usually used in armature coils but parallel conductors without transposition present non-uniform current sharing. In this manuscript, current sharing properties among three REBa₂Cu₃O<italic>_y</italic> parallel tapes with&#x002F;without a transposition in three-phase armature coil conditions, were investigated experimentally and analytically. The sample coils were prepared under the three-phase arrangement of armature coils for a two-pole rotating machine, and its branch currents were evaluated by Rogowski coils by applying AC transport current in liquid nitrogen at 77 K. We demonstrated that the introduction of the transposition was also an effective way to control the current sharing in rotating magnetic fields generated by the three-phase armature coils as well as single-phase situations. In addition, the influence of other phase armature coils on the current sharing was discussed via analytical calculations.

DOI： 10.1109/TASC.2024.3352521

Scopus

Akifumi Kawagoe, Ryunosuke Torii, Shinpei Nakagawa, Shun Miura, Hiroshi Miyazaki, Masataka Iwakuma .  Measurement System for Induced Currents in Superconducting Air-Core Rotors for Induction Motors .  IEEE Transactions on Applied Superconductivity34 ( 5 ) 5203205   2024年8月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

DOI： 10.1109/TASC.2024.3385737

Scopus

Miura S., Kobun A., Masuda Y., Kawasaki G., Miyazaki H., Kawagoe A., Sasa H., Yoshida K., Sato S., Iwakuma M. .  Current Distribution among Transposed Eight- and 16-parallel REBa2Cu3Oy Wires in Single-phase Armature Coils .  IEEE Transactions on Applied Superconductivity34 ( 5 ) 5201906   2024年5月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

Fully superconducting synchronous motors employing superconducting armature and field coils, have a great possibility for electric propulsion systems in aircraft applications, owing to their high output power density (kW/kg). To realize a large current capacity in REBa₂Cu₃O<italic>_y</italic> superconducting armature coils, we have proposed a cabling design for the transposed multi-strand parallel conductors. In this study, branch currents among eight- and 16-strand parallel conductors having only one transposition into a coil, were investigated. The analytical calculations showed approximately uniform branch current for the eight- and 16-strand conductors. According to the calculations, the deviations to the uniform branch current of eight-strand parallel conductors were &#x00B1; 7%. The approximately uniform current for the eight-strand conductors were also demonstrated experimentally by small-sized sample coils.

DOI： 10.1109/TASC.2024.3356436

Scopus

KAWAGOE A., YOSHIMO K., MOTOKI Y., OBANA T., TAKAYASU M. .  Investigation of Intertape Coupling Losses in YBCO-Stacked Cables .  Plasma and Fusion Research18 ( 0 ) 2405074 - 2405074   2023年8月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 プラズマ・核融合学会  

We investigated intertape coupling losses in yttrium barium copper oxide (YBCO)-stacked cables. YBCO stacked cables are being researched and developed as candidates for large 100 kA-class conductors for nuclear fusion. Here, we report intertape coupling losses in a conductor of 50 stacked tapes measured in liquid nitrogen. The measured conductor consists of soldered intertape connections. A copper layer surrounded the YBCO tape in the sample conductor. Fifty YBCO tapes were stacked, and the entire sample was bound with a copper tape and then impregnated with solder. This sample was approximately 100 mm long without twisting. The intertape coupling current flowed over the entire length of the sample conductor due to nontwisting. First, intertape resistance was estimated by comparing the measured and theoretical coupling losses. Subsequently, the coupling current paths in the cross-section of the sample were investigated. We found that intertape resistances were affected by the copper tape used to bind the stacked YBCO tapes.

DOI： 10.1585/pfr.18.2405074

Scopus

Miura S., Kobun A., Masuda Y., Nakamura K., Miyazaki H., Kawagoe A., Sasa H., Yoshida K., Sato S., Iwakuma M. .  Current Sharing among Transposed Three-Parallel REBa2Cu3Oy Tapes in Single-Phase Armature Coils .  IEEE Transactions on Applied Superconductivity33 ( 5 ) 5200306   2023年8月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

To realize a large current capacity in REBa2Cu3Oy superconducting coils, we have proposed a cabling design for the transposed multi-strand parallel conductors. This cabling design is also useful for a superconducting armature coil in a fully superconducting rotating machine system. Very recently, we developed an analytical method based on simple modeling, to roughly calculate the current distributions among the continuous strands in rotating machine conditions. In this manuscript, the current distributions predicted by the analytical method were compared with the measured values. Further, to understand the complex current distribution property for the three-strand parallel conductors, the turn number dependence of the current distribution with various transposition combinations was investigated. The current branches were measured under liquid nitrogen temperature of 77.3 K by Rogowski coils by applying AC transport current. The analytical method described the complex current distribution of the strands well, especially the coil with a large number of turns.

DOI： 10.1109/TASC.2023.3241824

Scopus

Hirano N., Onodera Y., Mito T., Motoki Y., Kawagoe A. .  Basic Research on a Magnetic Refrigeration System for Cooling to Liquid Hydrogen Temperature .  IEEE Transactions on Applied Superconductivity33 ( 5 ) 4702605   2023年8月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

Magnetic refrigeration technology is expected to be a highly efficient process at a temperature of around 20 K, which is the hydrogen liquefaction temperature. In magnetic refrigeration, a magnetic field change is applied to a magnetocaloric material (MCM) to obtain a magnetocaloric effect. In addition, since the greater the magnetic field change, the better the cooling characteristics, the magnetic field strength of permanent magnets is insufficient, and the use of superconducting coils that can generate strong magnetic fields with low power consumption is essential. We are researching and developing a static magnetic refrigeration system (SMRS) that does not have moving parts to obtain magnetic field changes, and generates them by altering the energizing current to the coil. The key to devising this system is an AC loss of the superconducting coil. In this study, we measured the AC loss under energization conditions of multiple palm-sized REBCO coils at liquid nitrogen temperature, and calculated the efficiency of the SMRS by improving the accuracy of the analysis method for evaluating the AC loss, based on the results. We report the results and discuss the technical feasibility of SMRS.

DOI： 10.1109/TASC.2023.3263786

Scopus

Takashima A., Onamyuda Y., Kobun A., Miyazaki H., Kawagoe A., Miura S., YYoshida K., Sato S., Sasa H., Iwakuma M. .  Current Distribution of Armature Coils Combining Two Different Sizes of REBCO Racetrack Double Pancakes .  IEEE Transactions on Applied Superconductivity33 ( 5 ) 4600905   2023年8月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

To realize a large current capacity in REBa2Cu3Oy superconducting coils, we have proposed a cabling design for the transposed multi-strand parallel conductors. This cabling design is also useful for a superconducting armature coil in a fully superconducting rotating machine system. Very recently, we developed an analytical method based on simple modeling, to roughly calculate the current distributions among the continuous strands in rotating machine conditions. In this manuscript, the current distributions predicted by the analytical method were compared with the measured values. Further, to understand the complex current distribution property for the three-strand parallel conductors, the turn number dependence of the current distribution with various transposition combinations was investigated. The current branches were measured under liquid nitrogen temperature of 77.3 K by Rogowski coils by applying AC transport current. The analytical method described the complex current distribution of the strands well, especially the coil with a large number of turns.

DOI： 10.1109/TASC.2023.3241822

Scopus

Miura S., Kobun A., Masuda Y., Miyazaki H., Kawagoe A., Sasa H., Yoshida K., Sato S., Iwakuma M. .  Development and assessment of simplified analytical method for current distribution among REBa2Cu3Oy parallel conductors in armature windings for fully superconducting rotating machines .  Superconductor Science and Technology36   065007   2023年6月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Superconductor Science and Technology  

Fully superconducting rotating machines employing REBa2Cu3O y (REBCO, RE = rare earth elements or Y) superconducting armature and field coils, are particularly interesting for aircraft applications, owing to their high output power density (kW kg−1). To achieve high current capability in superconducting coils, we have proposed a cabling design for transposed multi-strand parallel conductors. In the parallel conductor design, the REBCO strands are insulated from each other, except for both terminal ends, and transposed during the winding process to achieve uniform current distribution by cancellation of interlinkage magnetic flux between the strands. In this study, a simplified analytical method considering inductances was developed based on Laplace’s equation in cylindrical coordinates to roughly calculate the current distributions of multi-strands under armature coil conditions. The validity of the analytical method was investigated through current distribution measurements of the sample coils wound with two-strand parallel conductors. Consequently, the analytical method was validated with approximately 10% deviation under the experimental coil conditions. To establish a more accurate analysis method, certain improvements are needed.

DOI： 10.1088/1361-6668/acca4f

Scopus

Obana T., Kawagoe A .  Numerical Analysis of Hysteresis Loss in Stacked REBCO Tapes for Large Current-Carrying Conductors .  Plasma and Fusion Research18 ( 0 ) 2405013 - 2405013   2023年2月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 プラズマ・核融合学会  

We investigated intertape coupling losses in yttrium barium copper oxide (YBCO)-stacked cables. YBCO stacked cables are being researched and developed as candidates for large 100 kA-class conductors for nuclear fusion. Here, we report intertape coupling losses in a conductor of 50 stacked tapes measured in liquid nitrogen. The measured conductor consists of soldered intertape connections. A copper layer surrounded the YBCO tape in the sample conductor. Fifty YBCO tapes were stacked, and the entire sample was bound with a copper tape and then impregnated with solder. This sample was approximately 100 mm long without twisting. The intertape coupling current flowed over the entire length of the sample conductor due to nontwisting. First, intertape resistance was estimated by comparing the measured and theoretical coupling losses. Subsequently, the coupling current paths in the cross-section of the sample were investigated. We found that intertape resistances were affected by the copper tape used to bind the stacked YBCO tapes.

DOI： 10.1585/pfr.18.2405013

Scopus

Yuta Okade, Hiroshi Miyazaki, Hiromasa Sasa, Koichi Yoshida, Shun Miura Teruyoshi Sasayama, Takashi Yoshida, Akifumi Kawagoe, Masataka Iwakuma .  REBCO Trapezoidal Armature Windings for Superconducting Induction Motors .  IEEE Transactions on Applied Superconductivity32 ( 6 )   2022年9月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

DOI： 10.1109/TASC.2022.3160146

Scopus

Naoki Hirano*, Yuta Onodera*, Toshiyuki Mito*, Yuma Ueno, Akifumi Kawagoe .  Development of Static Magnetic Refrigeration System Using Multiple High-Temperature Superconducting Coils .  IEEE Transactions on Applied Superconductivity32 ( 6 ) 0500105   2022年9月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

DOI： 10.1109/TASC.2022.3152456

Scopus

Noda K., Sasa H., Miyazaki H., Miura S., Yoshida T., Sasayama T., Iwakuma M., Kawagoe A., Izumi T., Konno M., Sasamori Y., Honda H., Hase Y., Shutoh M. .  Numerical simulation of a high-power density 10 MW REBCO superconducting synchronous generator cooled by sub-cooled LN2 for low AC loss .  Journal of Physics: Conference Series2323 ( 1 )   2022年8月

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記述言語：日本語   出版者・発行元：Journal of Physics: Conference Series  

Generators used in electric aircraft require a high-power density, and AC loss is also a significant problem. We designed 10 MW REBCO superconducting synchronous generators at 64 K to achieve a power density of 20 kW/kg and low AC loss. In this study, electromagnetic analyses were performed using finite element method software. Consequently, the thickness of the back yoke is 50 mm or less so that the generator can meet the target power density. The method of decreasing the magnetic field of the armature winding and increasing that of the field winding was used to effectively reduce the AC loss. As a result, the generator achieved a high-power density of 21.0 kW/kg, reducing the AC loss from over 600 kW to 415 kW.

DOI： 10.1088/1742-6596/2323/1/012037

Scopus

Junya Oomura, Go Sato, Akifumi Kawagoe .  The calculation and measurement of electromagnetic energy flows for investigation of critical current estimation for high-temperature superconducting coil by means of pick-up coils .  IOP Conference Series: Materials Science and Engineering1240 ( 1 ) 012026   2022年6月査読

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IOP Publishing  

DOI： 10.1088/1757-899X/1241/1/012026

Scopus

Mito Toshiyuki ; Onodera, Yuta ; Otsuji, Maki ; Hirano, Naoki ; Takahata, Kazuya ; Yanagi, Nagato ; Iwamoto, Akifumi ; Hamaguchi, Shinji ; Takada, Suguru ; Baba, Tomosumi ; Chikumoto, Noriko ; Kawagoe, Akifumi ; Kawanami, Ryozo .  Improvement of Ic degradation of HTS conductor (FAIR conductor) and proposal of FAIR coil configuration for fusion device .  IEEE Transactions on Applied Superconductivity31 ( 5 )   2021年8月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

DOI： 10.1109/TASC.2021.3069923

Scopus

Experimental Evaluation of 1 kW-class Prototype REBCO Fully Superconducting Synchronous Motor Cooled by Subcooled Liquid Nitrogen for E-Aircraft .  IEEE Transactions on Applied Superconductivity31 ( 5 )   2021年8月査読

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE Transactions on Applied Superconductivity  

DOI： 10.1109/TASC.2021.3055452

Scopus

Yuma UENO, Naohiro NAGAMOTO, Akifumi KAWAGOE, Tetsuhiro OBANA, Makoto TAKAYASU .  Evaluation AC Losses in Large-Scale Conductors Consisting of Stacked REBCO Tapes .  Plasma and Fusion Research16   2405071   2021年6月査読 国際共著

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1585/pfr.16.2405071