AC losses in thin superconductors: the integral equation method applied to stacks and windings

Abstract

In this paper we present a method for computing transport current ac losses in interacting thin superconductors. The method solves the integral equations for the sheet current density distribution and is specifically developed for those configurations where the symmetry of the current density distributions allows writing the equation in a self-consistent form, without the need for using an auxiliary 2D model to describe the interaction between superconducting tapes. This results in very short computation times and therefore the model can be very useful for optimizing the design of superconducting devices. The method has been tested for different cases of practical applications and the ac loss results have been compared with those obtained with analytical models and with experiments.

Solution of 3D magnetization problems for superconducting film stacks

“…We set ( ( 13 ) are performed, for the spatially discretized problem, on each step of the ordinary differential equation solver until their convergence with a given tolerance. Here  is the relaxation parameter (as in [23], we used 0.7   ), () We note that if an infinite stack is densely packed ( figure 2, top), the solution is close to that for an infinite cylinder in a parallel field.…”

ENSYSTROB—Resistive Fault Current Limiter Based on Coated Conductors for Medium Voltage Application

“…For the simulations of the twins we used a 2-D finite-element model, based on the H-formulation of Maxwell equations [11]. The bifilar pancake is locally sufficiently modeled as a bifilar stack for the simulation of which we have used the integral equation model [12]. It has to be noted that the calculation of the losses in the bifilar stack arrangement can also be done analytically, if the critical state model is used to describe the superconductor's properties [13].…”

Simulation of Current Profile and AC Loss of HTS Winding Wound by Parallel-Connected Tapes

“…We therefore usually rely on numerical simulation to deeply understand the loss behavior of a winding in a microstructure. Currently, we can list more than one method that are capable of simulating ac loss of a winding even with hundreds of turns [17]- [20]. However, to our best knowledge, none of those methods can simulate the PC structure because simulating PC structures not only requires applying the current to a specific turn but also regulating the shunt resistance between turns.…”