A high-efficiency, high-power-density Sigma converter for a 48 V rack architecture in data centers is proposed in this paper. The Sigma converter is a quasi-parallel converter that uses a high-efficiency unregulated converter to deliver the bulk power to the load. A small buck converter is responsible for regulating the output voltage with prescribed dynamic responses. A design guideline for Sigma converter with integrated magnetics is provided in this paper. The unregulated converter is an LLC converter designed with a printed circuit board (PCB) winding matrix transformer, a structure which integrates four elemental transformers into one core. The buck converter is designed with discrete gallium nitride (GaN) devices and a PCB winding inductor. The proposed Sigma converter operates at 48 V input and 1 V-80 A output and can achieve a power density of 420 W/in3 as well as a peak efficiency of 94%.

中文翻译：

---

具有集成磁性元件的单级高效 48/1 V Sigma 转换器


本文提出了一种适用于数据中心 48 V 机架架构的高效、高功率密度 Sigma 转换器。 Sigma 转换器是一种准并行转换器，它使用高效的非稳压转换器向负载提供大容量功率。小型降压转换器负责以规定的动态响应调节输出电压。本文提供了具有集成磁性元件的 Sigma 转换器的设计指南。该非稳压转换器是一种采用印刷电路板 (PCB) 绕组矩阵变压器设计的 LLC 转换器，该结构将四个基本变压器集成到一个磁芯中。该降压转换器采用分立氮化镓 (GaN) 器件和 PCB 绕组电感器设计。拟议的 Sigma 转换器在 48 V 输入和 1 V-80 A 输出下运行，可实现 420 W/in3 的功率密度以及 94% 的峰值效率。