GaN HEMTs based Quad-Active-Bridge DC-DC Converter for PV-Battery-EV-Grid Systems

This paper aims to develop a flexible power management approach to interconnect multiple energy resources based on an isolated, monolithic multiport DC-DC power converter. Specifically, a high efficiency, ultra-compact Quad-Active-Bridge (QAB) DC-DC converter is proposed to interconnect photovoltaic (PV), battery energy storage (BES), electric vehicle (EV) charging/discharging, and a distribution grid. Fast-switching Gallium Nitride (GaN) high-electron-mobility transistors (HEMTs) are employed to achieve higher energy efficiency and power density. To meet the high voltage requirements on the DC grid port, a three-level active-neutral-point-clamped (ANPC) bridge based on 650V GaN HEMTs is developed. To provide galvanic isolation among different power ports, a high-frequency, multi-winding planar magnetic transformer is utilized to couple different power ports for flexible power management. The control and efficiency at four operating modes of the QAB converter are investigated for various weather conditions, and electro-thermal simulations for the QAB converter, including the planar transformer, are carried out in PLECS and Ansys software. Moreover, a 15-kW GaN HEMT based QAB DC-DC converter prototype is implemented for experimental verification.