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

Abstract

This paper presents an investigation on the AC losses in several typical superconducting composite conductors using the H-formulation model. A single superconducting strip with ferromagnetic substrate or cores and a stack of coated conductors with ferromagnetic substrates are studied. We consider all the coated conductors carrying AC transport currents and simultaneously exposed to perpendicular AC magnetic fields. The influences of the amplitude, frequency, phase difference and ferromagnetic materials on the AC losses are investigated. The results show that the magnetization losses of single strip and stacked strips have similar characteristics. The ferromagnetic substrate can increase the magnetization loss at low magnetic field, and decrease the loss at high magnetic field. The ferromagnetic substrate can obviously increase the transport loss in stacked strips. The trends of total AC losses of single strip and stacked strips are similar when they are carrying current or exposed to a perpendicular magnetic field. The effect of the frequency on the total AC losses of single strip is related to the amplitude of magnetic field. The AC losses decrease with increasing frequency in low magnetic field region while increase in high magnetic field region. As the phase difference changes, there is a periodic variation for the AC losses. Moreover, when the strip is under only the transport current and magnetic field, the ferromagnetic cores will increase the AC losses for large transport current or field.

Thin Shell Model of a Coated Conductor With a Ferromagnetic Substrate

“…Assuming an infinite magnetic permeability of the substrate, Mawatari ( [1], see also [5]) solved the problem analytically for a superconducting layer either in the Meissner state or described by the Bean critical-state model. For problems with a finite magnetic permeability of a substrate and different current-voltage relations characterizing the superconductor, various two-dimensional (2d) formulations have served a basis for the finite element approximation and numerical solution [4,6,[8][9][10][11][12]. The h-formulation, employed in [6,10,13] and often realized in a commercial finite element software, can be not the optimal choice because of a very high width-to-thickness ratio of a Manuscript receipt and submission dates will be inserted here.…”