High‐power‐density high‐efficiency LLC converter with an adjustable‐leakage‐inductance planar transformer for data centers

Abstract

LLC converters can achieve high efficiency, high‐ power density, wide gain range, and galvanic isolation. This study presents a high‐power‐density and high‐efficiency LLC converter with an adjustable‐leakage‐inductance planar transformer for the DC–DC conversion in data center power supplies. A planar transformer with adjustable leakage inductance is modelled and developed to provide an accurate design for resonant frequency and voltage gain. A detailed power loss analysis is performed. Furthermore, a thermal model is provided to aid in heat sink design. GaN devices are used in the converter to achieve high‐switching frequency and low‐switching loss. A 450 kHz, 360–400 V DC input, 12 V DC output, 750 W LLC converter prototype with an adjustable‐leakage‐inductance planar transformer is built and tested. The power density of the system is 15.4 W/cm 3 including an auxiliary power supply. The peak efficiency of the overall system is over 95%.