The transition arm multilevel converter — A concept for medium and high voltage DC-DC transformers

This paper proposes a dc/ac converter topology where each phase leg comprises a conventional series switch valve in one arm and a series connection of half-bridge chopper cells in the other arm. Operation with trapezoidal modulation is analyzed where the half-bridge modules have a reduced footprint and silicon area compared to standard modular multilevel converter modules. Furthermore, no arm inductance is required. The utilization of the proposed converter topology in medium and high voltage front-to-front dc-dc converter topologies is analyzed. Simulations investigate key features of the converter in comparison to other published topologies.