Due to the nonlinear properties of superconductors, modeling of high-temperature superconducting (HTS) devices is difficult, especially for the ones in large scale. In this paper, we develop the multi-scale model from a 2D planar geometry to a 2D axisymmetric geometry to successfully calculate ac loss of large-scale HTS coils. By applying appropriate boundary conditions, the infinite-turn coil is built in the 2D axisymmetric model to produce approximated current density for a HTS coil. Besides, the multi-scale model is improved in terms of coupling, so that sub-models can be connected in one file and the external data processing is not needed. Validation on accuracy and efficiency is demonstrated through a double-pancake coil. Results are compared with a conventional model that considers the superconducting characteristics on each turn of the coil in actual size. Our work shows the development and improvement of multi-scale model in the 2D axisymmetric geometry is feasible. Due to its high accuracy and efficiency, the developed multi-scale model can be a useful approach to analyze electromagnetic characteristics and calculate ac losses in large-scale HTS magnets.
|Journal||IEEE Transactions on Applied Superconductivity|
|Early online date||6 Feb 2019|
|Publication status||E-pub ahead of print - 6 Feb 2019|