Computer Science Course, Advanced Engineering Course, National Institute of Technology, Toyota College1
Department of Information and Computer Engineering, National Institute of Technology, Toyota College2
Department of Electrical and Electronic Engineering, National Institute of Technology, Toyota College3
Thanks to pinning effect of superconducting properties, HTS material is able to intensify the magnetic flux trapping compared with conventional permanent magnet. Magnetized HTS bulk is selected to use as field-pole magnet of the HTS motors and generators. However, flexibility of HTS bulk cannot stand for bending on the curved surface. To apply for rotor surface of the radial gap type motor, shape of the bulk needs to be fitted with some modification. On the other hand, HTS tape is possible to withstand against small bending more than 40-50 mm in radius.
From these backgrounds, our group conducts research of magnetized stacked field pole made of HTS tapes to apply for curved surface of rotor surface of radial gap type rotating machine.
In previous research, stacked model of HTS tapes revealed to trap magnetic flux by applying a strong magnetic field. This research shows possibility of replacing HTS Bulk with stacked model of HTS tape. Magnetization test to stacked models made by Bi2223 and GdBCO HTS tapes with 4 mm in width with different stacking patterns was conducted. As a result, we confirmed that stack patterns for HTS tape were correlated with magnetic field distribution. In addition, choice of material was resulted in the magnetic field density following current density of HTS material itself.
In this study, to enhance current density against the volume of the magnet, we prepared samples of stacks with 300 A class Gd123 HTS tapes with 12 mm in width.
The size of stacked model was 25 mm in length × 25 mm in width × 5 mm in height and selected stacked patterns in previous work was adopted. Permanent magnet (<0.2 T) and Bi2223 HTS coil (<0.3 T) used for magnetization and obtained magnetic field distribution of the samples. Evaluation of magnetizing properties was carried out by comparing 2D plots of trap magnetic flux density.
As a result, stacked models of HTS tapes with 12 mm in width improved a trapped magnetic flux density of stacked models compared with HTS tapes with 4 mm in width. The result shows the increasement of current density in superconducting material per volume is able to enhance the trapped flux property. Controlling of trap magnetic flux density by using stacked model of HTS tapes provide new approaches to develop HTS applications.
Part of this work has been financially supported by KAKENHI 19K15221.
Keywords: HTS tape, Field pole, Stack, Magnetization