A GaN based Dual Active Bridge Converter for Energy Storage Systems

Renewable energy sources are intermittent in nature and they are often used in conjunction with energy storage systems to ensure a continuous flow of power. Bidirectional DC/DC converters serve as an intermediary between the energy storage hardware and the inverter connected to the grid. Dual active bridge (DAB) converters are well suited for this application, especially when the power is greater than 1 kW. They offer bidirectional power flow and the power devices can achieve zero-voltage-switching (ZVS). Furthermore, gallium nitride (GaN) based transistors have many attributes that enable them to outperform silicon (Si) MOSFETs in this topology. This research compares the performance of a DAB converter designed with GaN transistors to one built with Si MOSFETs. Additionally, it demonstrates how numerical modeling techniques such as boundary element method (BEM) and finite element method (FEM) can be utilized to reduce parastics during PCB layout and facilitate transformer design. A hardware prototype was built for 48 V to 400 V conversion with a rated power of 2 kW.