Analysis of perpendicular magnetic fields on a 1 MVA HTS transformer windings with flux diverters

In high temperature superconducting (HTS) transformer with double pancake windings, the perpendicular component of leakage magnetic flux density (B/sub r/) applied to HTS tapes of double pancake windings is larger than that of solenoid windings, which acts as a cause to decrease the critical current in HTS tape and increase AC loss. In this paper, in order to reduce the B/sub r/ applied to HTS windings, the use of ferrite flux diverters is presented. Flux diverters are located in between the primary windings and the secondary windings, and must be made of low-loss materials to minimize the heat. And electromagnetic analysis of a single-phase 1 MVA 22.9 kV/6.6 kV HTS transformer with flux diverters in HTS windings was accomplished. The variation of B/sub r/ applied to the secondary windings and magnetic flux density in flux diverters were analyzed by changing their relative permeability of flux diverters respectively. Suitable relative permeability of flux diverters to reduce B/sub r/ applied to HTS windings was selected, considering flux diverter losses by increment of B in flux diverters.