Control and Fault Monitoring of Modular Dual Active Bridge Converters

Modular DC-DC converters are a promising solution for many applications due to their flexible adaption to various voltage and power levels. However, this modularization involves an increased control effort to achieve symmetrical voltage and current distribution among the converter modules. In this work, a three-phase modular Dual Active Bridge (DAB3) converter is considered, wherein the individual converters are connected in input-series-output-parallel (ISOP) configuration. In order to address the problems of unequal power distribution among the modules, a new control strategy with uniform input-voltage distribution is proposed and verified using real-time simulation. Furthermore, the fault ride-through (FRT) capability of two ISOP connected DAB3 converters is simulated for a short circuit DC fault at the output. Finally, a novel pulse pattern generator (PPG), executed in VHDL, is used to verify the modulation strategy employed for FRT.