Abstract Body

We propose simple expressions to estimate AC losses in high temperature superconducting (HTS) tape windings located inside iron core slots. This study involves a two-dimensional (2D) analysis model representing a cross-section of one of semi-closed slots in a stator iron core, separated by a narrow gap from a rotor iron core [1]. The HTS windings within the iron core slots are modelled as stacks of infinitely thin superconducting (SC) strips placed at even intervals. The AC losses generated in the SC strips with alternating transport currents are numerically calculated by means of finite element methods. It is assumed that the transport property of the SC material is subjected to the critical state model, in which the critical current density is independent of the local magnetic field. The SC strips and vacuum regions are formulated using the current and magnetic vector potentials, respectively [2]. This study aims to quantitatively evaluate the effects of various parameters such as current amplitude, frequency, number of stacked strips, gap between strips, slot width, etc., on AC losses. We attempt to derive simple expressions that almost reproduce the obtained numerical results of AC losses.

References

[1] K. Kajikawa et al.: J. Supercond. Nov. Magn. 24 (2011) 987.
[2] H. Zhang et al.: Supercond. Sci. Technol. 30 (2017) 024005.

Acknowledgment

I would like to express my gratitude to Professor Kazuhiro Kajikawa for his extensive guidance and valuable advice throughout the implementation of this study. I sincerely appreciate his generous support and assistance.