3D finite element modelling on racetrack coils using the homogeneous T-A formulation

Abstract High temperature superconducting (HTS) coated conductors (CCs) hold a promising feature in use of manufacturing kinds of magnets, coils, cables and so on. Its advantage on large-current-transporting capacity makes it suitable in MW-class machines and other large power electrical applications. In most situations, corresponding simulations were modeled in a 2D architecture. While, more complicated influences on ends of machines have been ignored artificially due to the simplification on model dimensions and huge expanses on the computational time. Therefore, comprehensive and full-scale models, which cannot easily be simplified as 1D or 2D representations, are urgent to analyze their electromagnetic behaviors in the early-stage design with an acceptable speed. In this paper, we propose a homogeneous T-A formulation for the 3D racetrack coil for the first time, which is treated as an anisotropic bulk-like equivalent to be modeled. Only the superconducting layer of HTS CCs has been preserved and other layers are ignored while still retaining its electromagnetic characteristics. This method in this paper has been fully verified with the widely accepted H formulation. However, the computational expense in T-A model is more than that of H model. At last, AC loss of a manufactured HTS double racetrack coil of one synchronous generator was measured and its experimental results are in good agreements with numerical profiles. This work has a guiding significance to accelerate the pace of 3D model and simulation in HTS applications.