High frequency characteristics of magnetic shielding type transformer using plural bulk superconductors

In a transformer using a ferromagnetic core, the magnetic flux comes to leak easily from the core at the higher frequency range. Thus, we have examined the magnetic shielding of a magnetic circuit of the transformer with plural bulk high temperature superconductors (HTSs) in order to improve characteristics of the transformer at the higher frequency range. From previous researches, it was confirmed that the secondary voltage and the power transfer efficiency of the transformer with the bulk HTSs shielding increased. In this research, it was examined to make surrounding the transformer with the bulk HTSs double in order to strengthen the magnetic shielding with the HTSs, and characteristics of the transformer were evaluated at the further high frequency range. From experimental results, it was confirmed that the characteristics of the transformer were excellent at 100 kHz or more.