Design and investigation of losses of a low-current HTS AC cable for a promising cryogenic generation system

Abstract

Currently, there are a large number of projects dedicated to electric machines aimed at use in the field of transport and equipped with windings made of high-temperature superconductors (HTS). These machines in their majority have rated currents significantly less than 1kA, which is a too low value for AC HTS cables in the power industry, where current values can reach up to 10kA. On the other hand, connecting, for example, an electric generator with cryogenic cooling and its load (which, most likely, will also have cryogenic cooling) with copper wires on board of a vehicle does not look like an effective solution. This article is devoted to the development of the concept of an alternating current transmission system for machines with a rated current of less than 1 kA through HTS cable. In order to achieve a compact design, it was decided to use a cable consisting of stacks of second-generation (2G) HTS tapes. A series of experiments was carried out with different numbers of tapes and directions of current in them for stacks of 2, 4 and 6 the HTS tapes. The results were compared with finite element modeling. The article shows that when current flows in adjacent cable HTS tapes in opposite directions, like as in bifilar windings, it is possible to achieve a significantly lower level of losses per tape than when current flows in the cable tapes in one direction.