Numerical analysis on magnetic field of HTS transformer with different geometry

In a high-temperature superconducting (HTS) transformer leakage magnetic field, especially its radial component, decreases the critical current and increases the ac losses in the tapes. Because of zero resistance of HTS tapes a slight unbalance among the branch inductances of the windings may result in heavy circulating current, however, an accurate calculation of it must depend on the magnetic field analysis. Thus, a numerical analysis of the leakage magnetic field is especially necessary for an HTS transformer design. In this paper the leakage magnetic field of several transformer geometries is studied by finite element method, and based on it, the circulating current distribution is calculated. Some suggestions for improving the leakage field and circulating current distribution are presented to make HTS transformers more efficient.