Numerical study for the impact of current sharing effect upon dynamic behaviour of DC-carrying HTS coils under alternating magnetic fields

Numerical characterization for the dynamic behaviour of DC-carrying HTS coils subjected to alternating magnetic fields is crucial for its design and protection. In conventional approaches, only superconducting layers are modeled. The missing current sharing effect in those models results in the overestimation of dynamic voltage/resistance. In reality, the transport current will migrate into the metal layers, and therefore the dynamic voltage/resistance is limited. In this paper, we present an equivalent modeling approach (EPM) instead of modeling the real geometry which will cost massive computation resources. The effectiveness of the approach is validated against a full-scale model containing all the layers. Then, this approach is applied to estimate the dynamic behaviour of a multiturn racetrack HTS coil. It is found that the current sharing effect mainly happens at the outer layers of the coil due to the shielding effect, and is enhanced with the increase of external field amplitude then gradually spreads to the inner layers. Moreover, the competition between the transport current and the induced current in the metal layers is observed.