A GaN-based High Step-Up Half-Bridge Resonant Converter for Interfacing PV Modules to DC Data Centers

A high-frequency transformer isolated dc-dc converter with high step-up ratio (more than 10) is normally used to interface the low voltage (~30V) photovoltaic (PV) modules with the high voltage (~380V) distribution bus of the dc data center. The requirement of high step-up gain of voltage compromises the efficiency of this converter due to the increased conduction loss in the low voltage side of the transformer. This paper presents a GaN-based isolated dc-dc converter that achieves both high step-up voltage gain and high efficiency with minimal component count. The converter utilizes a half-bridge series-resonant circuit, with duty-ratio controlled pulse width modulation. A new equivalent circuit of the primary side network of the converter is proposed that determines the optimum values of magnetizing inductance and deadtime for minimizing circulating current without affecting the soft-switching of the switches. The design is verified with a 240W laboratory prototype. The experimental result proves the claimed advantages and demonstrates the California Energy Commission (CEC) efficiency of 96.03% and the European efficiency (EU) of 95.56%.