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In recent years, the $H$ formulation of Maxwell's equations has become the de facto standard for simulating the time-dependent electromagnetic behavior of superconducting applications with commercial software. However, there are cases where other formulations are desirable, for example for modeling superconducting turns in electrical machines or situations where the superconductor is better described by the critical state than by a power-law resistivity. In order to accurately and efficiently handle these situations, here we consider two approaches based on the magnetic vector potential: the $T$ - $A$ formulation of Maxwell's equations (with power-law resistivity) and the implementation of a quasi critical state model (QCSM) with a steep $E$ - $J$ relationship limited at $J_{\rm c}$. In this article, we extend the $T$ - $A$ formulation to thick conductors so that large coils with different coupling scenarios between the turns can be considered. We also discuss the QCSM in terms of its ability to calculate ac losses: in particular, we investigate the dependence of the calculated ac losses on the frequency of the ac excitation and the possibility of using quick one-step (instead of full-cycle) simulations to calculate the ac losses. [ABSTRACT FROM AUTHOR]

Abstract: Uniformity of superconducting layer can play important role in various applications of coated conductor tapes. For example a degradation of critical current density at the tape edges causes significant elevation of transport AC loss compared to the uniform tape with the same critical current. Then the information about tape uniformity is essential when a valid AC loss prediction should be obtained by a numerical simulation. For this purpose we investigated experimentally the distributions of magnetic field above the tape surface obtained by Hall probe mapping. An advanced inversion procedure has been developed to resolve the critical current distribution across the tape width. The results obtained for SuperPower̈ CC tapes with non-magnetic substrate are presented and the implications on the AC loss behaviour are discussed. [Copyright &y& Elsevier]