A comparative study of three-phase dual active bridge topologies and their suitability for D-Q mode control

A comparative evaluation of three different three-phase Dual Active Bridge (DAB) topologies with a 15-kV Si-IGBT based three-level converter at the high-voltage side and 1200-V SiC-MOSFET based converters in three different arrangements at the low-voltage side are compared. The proposed DABs are an integral part of a solid state transformer which connects a 13.8-kV distribution grid and a 480-V utility grid. The three-level converters connected at the high-voltage side in each topology with 30° zero-enforcing and proposed arrangements at low-voltage side of the high frequency-link transformer help to reduce dominant harmonic currents. Thus harmonic-free currents in the high frequency link transformer are achieved without pulse-width modulation which can be utilized for D-Q Mode smooth-control.