Design considerations for a high-power dual active bridge DC-DC converter with galvanically isolated transformer

Abstract

Multi-megawatt scale isolated DC-DC converters are likely to become increasingly popular as means to interconnect the MVDC grids of different voltage levels. Threephase dual active bridge DC-DC (3DAB) converters operating with the zero-voltage switching (ZVS) is a promising candidate for the target multi-megawatt application. This paper presents a systematic approach of the design considerations for a 3DAB converter. Firstly, the use of snubber capacitors in medium voltage and medium frequency operating conditions is proposed. Snubber capacitor influence on turn-off current levels and ZVS operating range are introduced and analyzed. In addition, details of thermal management design are introduced. It is established through power loss analysis that the proposed design method reduces the semiconductor losses substantially at full load conditions. Finally, the proposed method has been validated from a 10kW simulation model using PLECS software package.

Current-Fed Multipulse Rectifier Approach for Unidirectional HVDC and MVDC Applications

“…For the first requirement, compatibility with medium/high voltage, the main options that have been presented in the literature are based on the Dual Active Bridge (DAB) [11], [12] or based on the Modular Multilevel Converter (MMC) [13], [14]. However, the high dv/dt and the high voltage steps applied in medium/high frequency transformers [15] are still an issue because of their interaction with transformer parasitic elements that may cause two principal effects.…”