Performance Evaluation of a Double Pancake Modular Coil Wound by Multi-Layer Spiral HTS Cable

Assembling high-temperature superconducting (HTS) tapes into multi-layer spiral HTS cable has been recently adopted in the modular design of large-scale superconducting magnetic energy storage (SMES). However, complicated three-dimensional geometry of HTS tapes in the spiral cable hindered the numerical analysis on the electromagnetic characteristics of the spiral cable as well as the cable-based coil. In this paper, a partial-size model is proposed with appropriate geometrical simplifications, including symmetrical approximation, partialization and superposition. After preliminarily validated by critical current measurement, the partial-size model was used to simulate the transport ac loss characteristics. Results shows that disparity of ac loss in different turns correspond to the non-uniform magnetic field distribution. Furthermore, alternating magnetic field would generate current loop in turns, arousing additional magnetization loss component, which is an unexpected huge burden to cryogenic system and needs future optimization.