Studies of ac losses in superconducting materials, particularly in pancake coils, are of great importance for a better understanding of the superconductivity phenomena and its applications in power systems. Due to different technical difficulties, these studies are usually performed considering one of two approaches: considering superconducting coils of few turns and studying ac losses in a large frequency range versus superconducting coils with a large number of turns but measuring ac losses only in low frequencies. In this paper, ac losses are simulated and verified experimentally in a 128 turn Bi-2223 coil in a range of frequencies from 72 Hz till 1152 Hz. Obtained results show a frequency-dependent behavior. Experimental results are compared to those obtained from two different numerical modeling methods: one using commercial software based on finite-element methods and another using a variational method approach. All obtained results agree, validating the simulations and serving as basis for simulations with larger high temperature superconducting coils.
- AC losses
- BI-2223 coils
- finite-element method (FEM)
- minimum electro-magnetic entropy production (MEMEP)
- numerical modeling