Hysteresis Loss Improvement in HTS Transformers Using Hybrid Winding Schemes

The amount of hysteresis losses is a key parameter for the design of high-temperature superconducting (HTS) transformers. Leakage field, particularly its radial component, decreases critical current and increases hysteresis losses in HTS tapes. Prior art proposed the adoption of two auxiliary windings to an HTS transformer for minimizing the leakage flux densities by generating a field that opposes the leakage field, thereby reducing the hysteresis loss in an exemplary HTS transformer. In this paper, a proposed design will become prominent by obtaining a variant of distributive ratios via an intelligent choice of the secondary-primary-secondary-primary turn ratios in the neighborhood of the auxiliary windings to produce magnetic poles canceling or diminishing the corresponding leakage fields to the maximum effect. The mentioned schemes require accurate, yet efficient, advanced numerical techniques using 3-D solver of FLUX software for a precise calculation of the leakage flux density and hysteresis losses in an exemplary HTS transformer as a precious guide.