DC Characterization of a Circular, Epoxy-Impregnated High Temperature Superconducting (HTS) Coil

TL;DR

This paper presents a detailed DC characterization of a YBCO-based epoxy-impregnated HTS coil, revealing non-uniformities and variations in superconducting properties along its length, crucial for applications in electric machines and energy storage.

Contribution

It introduces a multi-tap measurement approach to analyze the DC behavior of a circular HTS coil, highlighting the non-uniformity and its impact on superconducting properties.

Findings

Non-uniformity along the coil length affects superconducting performance.

Decreased n-value and critical current in non-uniform regions.

Detailed voltage measurements provide insights into coil behavior.

Abstract

Direct current (DC) characterization of high temperature superconducting (HTS) coils is important for HTS applications, such as electric machines, superconducting magnetic energy storage (SMES) and transformers. In this paper, DC characterization of a circular, epoxy-impregnated HTS coil made from YBCO coated conductor for use as a prototype axial flux HTS electric machine is presented. Multiple voltage taps were utilized within the coil during measurement to help provide further detailed information on its DC behavior as a function of length. Based on the experimental results, there exist regions of non-uniformity along the length of superconductor in the coil, resulting in non-ideal superconducting properties of the coil. By studying the current-voltage (I-V) curves across different regions, it is found that a decreasing n-value and critical current exists in the non-uniform parts of the HTS coil.