Development of an edge-element model for AC loss computation of high-temperaturesuperconductors

Abstract

This paper presents a new numerical model for computing the current density, fielddistributions and AC losses in superconductors. The model, based on the direct magnetic fieldH formulation without the use of vector and scalar potentials (which are used inconventional formulations), relies on first-order edge finite elements. These elements areby construction curl conforming and therefore suitable to satisfy the continuityof the tangential component of magnetic field across adjacent elements, withno need for explicitly imposing the condition . This allows the overcoming of one of the major problems of standard nodal elements withpotential formulation: in the case of strong discontinuities or nonlinearities of thephysical properties of the materials and/or in presence of sharp corners in theconductors’ geometry, the discontinuities of the potentials’ derivatives are unnaturaland without smoothing artifices the convergence of the algorithm is put at risk.In this work we present in detail the model for two-dimensional geometries and we test itby comparing the numerical results with the predictions of analytical solutions for simplegeometries. We use it successively for investigating cases of practical interest involvingmore complex configurations, where the interaction between adjacent tapes isimportant. In particular we discuss the results of AC losses in superconductingwindings.