Flux-transfer losses in helically wound superconducting power cables

TL;DR

This paper analyzes flux-transfer losses in helically wound high-temperature superconductor power cables, emphasizing the effects of magnetic substrates and winding angles on ac losses.

Contribution

It presents a detailed formalism for calculating flux transfer losses, including the impact of magnetic substrates and winding configurations.

Findings

Flux transfer losses increase with magnetic substrates.

Opposite winding angles reduce flux transfer losses.

The formalism enables precise loss calculations for cable design.

Abstract

Minimization of ac losses is essential for economic operation of high-temperature superconductor (HTS) ac power cables. A favorable configuration for the phase conductor of such cables has two counter-wound layers of HTS tape-shaped wires lying next to each other and helically wound around a flexible cylindrical former. However, if magnetic materials such as magnetic substrates of the tapes lie between the two layers, or if the winding pitch angles are not opposite and essentially equal in magnitude to each other, current distributes unequally between the two layers. Then, if at some point in the ac cycle the current of either of the two layers exceeds its critical current, a large ac loss arises from the transfer of flux between the two layers. A detailed review of the formalism, its application to the case of paramagnetic substrates including the calculation of this flux transfer loss is presented.