Comparison of first- and second-order 2D finite element models for calculating AC loss in high temperature superconductor coated conductors

Purpose - The purpose of the paper is to provide a comparison of first- and second-order two dimensional finite element models for evaluating the electromagnetic properties and calculating AC loss in high-temperature superconductor (HTS) coated conductors. Design/methodology/approach - The models are based on the two-dimensional (2D) H formulation, which is based on directly solving the magnetic field components in 2D. Two models one with a minimum symmetric triangular mesh and one with a-single-layer square mesh are compared based on different types of mesh elements: first-order (Lagrange - linear) and second-order (Lagrange - quadratic) mesh elements, and edge elements. Findings - The number and type of mesh elements are critically important to obtain the minimum level of discretization to achieve accurate results. Artificially increasing the superconductor layer and choosing a minimum symmetric mesh with triangular edge elements can provide a sufficiently accurate estimation of the hysteretic superconductor loss for a transport current. Originality/value - This paper describes how the selection of mesh type and number of elements affects the computation speed and convergence properties of the finite element model using two different types of meshing. It offers an insight into the different factors modelers must consider when modeling HTS coated conductors and the methods that may be applied when extending the model to complex device geometries, such as wound coils.