Study on ac losses of HTS coil carrying ac transport current

Theoretical and experimental study of AC loss in high temperature superconductor single pancake coils

“…Alternatively, L 0 can be found as that at which V c at low amplitudes has a real and imaginary harmonics with the same value, as is predicted for a circular wire[15]. Actually, both ways of determining L 0 are equivalent, since for the low field limit the first real harmonic approaches zero 6. (See previous footnote.…”

“…Then, mainly for mechanical reasons, one of the most feasible ways of manufacturing a winding is to form a pancake coil (or sets of piled pancake coils). Up to this time, only a few theoretical works supported by experiments have been dedicated to the AC loss of pancake coils [3,[5][6][7][8][9][10].…”

“…From these references, in [5,8] the experimental results are compared to existing approximated analytical expressions or only a qualitative theoretical discussion is given. References [6,7] are based on relating the measured (or simulated) AC loss on a single tape under uniform applied field and the local average magnetic field of the coil. However, as discussed in [11], the interaction between tapes strongly influences the AC loss under a certain background external field.…”

Modeling of Dynamic Current Distribution in REBCO Insulated Coils Using a Volume Integral Formulation for Protection Purpose

“…Electromagnetic models of HTS devices using the Finite Element Method (FEM) have already been tested successfully by other teams, especially for AC losses computations [4]- [7], but meshing (high aspect ratio of coated conductors layers) as well as nonlinear convergence issues make these methods quite challenging to use [8]. We propose a more flexible approach based on a Volume Integral Formulation associated to the Partial Element Equivalent Circuit (PEEC) method [9] and adapted to 2D axisymmetric problems, whose main advantage is to require a mesh for active regions only, particularly convenient for RE-BCO coil modeling as the active regions are only defined by the very thin superconducting layer (as long as the tape is not transiting, otherwise all conducting layers should be considered too, as well as a thermal coupling).…”