[APP2] Magnets, Electric power devices, Rotating machines

[APP2-16] Effect of Magnetic Shielding on Current Sharing in Armature Coils Composed of Three-Parallel Conductors

*Goki Kawasaki^1,2, Yudai Kimura², Tomohiro Inoue², Masayuki Ishihara², Kohei Yoshida², Shun Miura³, Hiroshi Miyazaki², Akifumi Kawagoe⁴, Masataka Iwakuma⁴ (1. National Institute of Technology, Miyakonojo College (Japan), 2. Kyushu University (Japan), 3. National Institute for Fusion Science (Japan), 4. Kagoshima University (Japan))

Keywords:

Armature Coil,Superconducting Motor,Parallel Conductor,Current Distribution,Shield

A fully superconducting synchronous motor is a key technology for the realization of electric aircraft systems. This type of motor is expected to operate under low-voltage and high-current conditions, which necessitates a significant increase in the current capacity of the armature coils. To achieve this, various approaches have been proposed; among them, we focus on the transposed parallel conductors composed of superconducting tapes. To simplify analysis and experiments for the current distribution characteristics between parallel conductors in the armature coils of superconducting synchronous motors have been studied without considering the effects of surrounding structures such as back yokes and superconducting magnetic shields. However, in actual motor systems, the presence of a back yoke allows magnetic flux to penetrate perpendicularly, significantly altering the magnetic field distribution. These effects can disturb the inductance balance between conductors and potentially reduce the effectiveness of transposition configurations. This study aims to analytically clarify the influence of such surrounding structures on current distribution and to optimize transposition configurations. The analysis focuses on armature coils composed of three-strand parallel superconducting conductors. The current distribution is evaluated using both analytical formulas that consider configurations including either a back yoke. The dependence of the current distribution in a three-strand parallel conductor on the distance between the armature coil and the back yoke or the superconducting shield was analyzed. As the distance between the coil and the back yoke increases, the current distribution converges to a constant value and thus its influence decreases; however, the power density is reduced because the mass increases with the radius of the back yoke. Therefore, to achieve a lightweight design, it is necessary to place the back yoke close to the coil. Hence, the aim of this study is to clarify the optimal transposition configuration when a back yoke is present, and to establish a method of achieving uniform current distributions that is suitable for actual motor configurations.