AC losses in coated conductors

Abstract

Future use of coated conductors in electric power applications like transmission cables, transformers or fault current limiters is sensitive to the amount of dissipation in the AC regime. This paper analyses factors controlling AC loss of coated conductors in typical configurations: the self-field case when transport current generates the magnetic field, and the case of AC applied field where the orientation of magnetic field with respect to the superconducting layer plays a significant role.We illustrate that a high-quality CC tape with non-magnetic substrate follows rather well the models developed for a thin strip. However, to meet an excellent agreement between experiment and theoretical prediction a detailed knowledge of the superconductor properties is necessary and a numerical method must be involved.In the case of a superconducting layer deposited on a ferromagnetic substrate theoretical predictions give only basic directions and one must rely on numerical simulations entirely. We demonstrate that, with the help of a dedicated analysis of experimental data, very good AC loss prediction is also possible for superconductor-ferromagnetic composites. Novel designs of coated conductor architectures can be developed in this way.

Finite-element simulations of hysteretic ac losses in a bilayer superconductor/ferromagnet heterostructure subject to an oscillating transverse magnetic field

“…With the above assumption for J c in mind, this peculiar dependence of hysteretic ac losses cannot be explained by allowing for a diminution of J c at high values of H a , despite such considerations recently. 12 Nonmonotonic variations of hysteretic ac losses with H a have indeed been found in other simulations with constant J c , nonetheless. 13 It is for these reasons that we take a fresh look at the principal effects of a ferromagnetic support on hysteretic ac losses in a superconductor strip by making recourse to Bean's model of the critical state 14 and exploiting magnetostatic-electrostatic analogs.…”

“…[2][3][4][5] For coated conductors in bilayer or multilayer form, there is still controversy about experimental and theoretical results. [6][7][8][9][10][11][12][13] Some experiments demonstrate a monotonic rise of hysteretic ac losses with increasing permeability of ferromagnetic constituents, 10 while others show a contingent reduction of such losses due to ferromagnetic supports. 6,9 Finite-element simulations of transport currents vindicate the buildup of hysteretic ac losses and their growth with the permeability of the supports; 8,12 by contrast, hysteretic ac losses in the presence of an oscillating applied magnetic field may increase for low, and decrease for moderate, amplitudes H a of this field as compared to nonmagnetic supports, 12 whereas magnetization losses seem to only weakly hinge on magnetic supports.…”

“…[6][7][8][9][10][11][12][13] Some experiments demonstrate a monotonic rise of hysteretic ac losses with increasing permeability of ferromagnetic constituents, 10 while others show a contingent reduction of such losses due to ferromagnetic supports. 6,9 Finite-element simulations of transport currents vindicate the buildup of hysteretic ac losses and their growth with the permeability of the supports; 8,12 by contrast, hysteretic ac losses in the presence of an oscillating applied magnetic field may increase for low, and decrease for moderate, amplitudes H a of this field as compared to nonmagnetic supports, 12 whereas magnetization losses seem to only weakly hinge on magnetic supports. 8 In keeping with numerical studies cited before, 12 theoretical predictions emerge from analytical studies of a planar superconductor/ferromagnet heterostructure made up of an infinitesimally thin superconductor strip and an infinitesimally thin ferromagnetic support; the two constituents being described, respectively, by the sheet current J, with a ͑field-independent͒ critical value J c , and infinite permeability, → ϱ.…”

Influences of Ferromagnetic Substrate on Microwave Surface Resistance of Type-II Superconductors

“…In the present work, a method based on the finite element method (FEM) is used, which is similar to the approach employed by Gömöry et al [31]. The governing …”

Effect of the magnetic material on AC losses in HTS conductors in AC magnetic field carrying AC transport current

“…The field dependence of the relative magnetic permeability and constant relative magnetic permeability in the ferromagnetic substrate are used to study the AC losses of coated conductors. [25][26][27][28][29][30][31] Furthermore, some researchers also employed the complex field method to study the electromagnetic behaviors in superconducting strips with magnetic substrate. [32][33][34] Some classic and novel methods available in the literature could be used to carry out electromagnetic modeling of superconductors.…”