Design of 98.8% Efficient 400-to-48-V $LLC$ Converter With Optimized Matrix Transformer and Matrix Inductor

Abstract

Data centers have seen a rapid increase in power consumption in recent years, and the 48 V power architecture has gained popularity due to its efficiency. However, the cost of efficient power supplies remains challenging due to their complicated magnetic designs. The search for efficient and cost-effective power supplies continues. This paper focuses on the implementation of the DC-DC stage of the power supply unit for the 48 V data center bus architecture. In this paper, we present a design process for a high-efficiency, high-power-density 3 kW 400 V to 48 V LLC converter for use in data centers. Through optimization of the matrix transformer's geometry, turn number, and resonant frequency, we achieve superior efficiency and power density compared to state-of-the-art designs. To address challenges with the printed circuit board PCB-based inductors, we propose the use of a resonant matrix inductor, which reduces the number of stacked PCB layers, simplifies the winding implementation, and lowers the AC loss. By integrating the matrix inductor with the matrix transformer, we create a modular and scalable magnetic structure suitable for a wide range of voltages and currents. We also introduce EMI shielding for the matrix transformer with a full-bridge rectifier, resulting in an 18 dB reduction in common-mode noise. The prototype achieved a peak efficiency of 98.8% and a power density of 600 W/in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> , demonstrating the effectiveness of the proposed design.