Comparison of Modulation Strategies for GaN-based Quad-Active-Bridge DC-DC Converter for Microgrid Systems

This research focuses on the development of an ultra-compact and high-efficiency quad-active-bridge (QAB) DC-DC multiport converter, which can be used to interconnect photovoltaic (PV) panels, battery energy storage (BES), and electric vehicles (EVs) with a DC distribution grid. Emerging gallium nitride (GaN) switching devices are utilized to achieve high switching frequency, high efficiency, and high power density. Additionally, a multi-winding planar transformer is employed in the QAB converter to provide galvanic isolation and interconnect different power ports for flexible power flow management. Single-phase shift (SPS), extended-phase shift (EPS), and dual-phase shift (DPS) modulation strategies are investigated and compared to regulate the power flow in various operating modes. Electrothermal modeling and simulation of the QAB converter are conducted, and a 15 kW GaN-based QAB converter prototype is developed for experimental validation.