Dual active bridge converter as a part of the DC microgrid

Mikołaj Koszel

supervisor: Roman Barlik

DC microgrid seems to be a solution for boosting transformation to renewable energy sources of energy. Locally installed energy storage can overcome the most significant problem, which is the instability of RES. From a prosumers' point of view, energy storage will help to use more produced energy on theirs' own need and work independently during a blackout. A DC/DC converter is essential for transferring energy between voltage sources (such as photovoltaics) and energy storage. Such a converter should be able to work bidirectionally and provide galvanic isolation. A dual active bridge is a topology with plenty of advantages such as simple structure, easy control of power flow, the possibility of soft-switching commutations, and high power density.

To allow high power flow (e.g., in fast EV chargers), parallel connection of converters is legitimate. Converters should be switched on the microgrid with soft-start algorithms and additional contactors to achieve undisturbed work with minimized overcurrent and overvoltage events. Another essential issue is sharing the power flowing through paralleled connected converters to achieve minimum power losses. Working in light load mode requires the usage of sophisticated control. Simulation designing of the system control should be supported by detailed mathematical modeling.