The increase of power requirements per server rack, especially in the 48V bus architecture is demanding the increase of rated power and power density per power supply to fit as many power supplies in the server rack power shelf as possible. Due to the trade-off between fabrication cost and efficiency (running cost) of the power supply, the design of efficient but yet less labor-intensive power supply is important. This paper discusses methods to design DC-DC unit of the 3kW power supply for the 48V architecture with easier manufacturability and lower cost. Prototype for 400V/48V 3kW 1MHz is demonstrated.

The power electronics industry seeks more efficient power delivery and higher power density year-by-year. Resonant converters, such as the three-element resonant LLC converters, have been intensively studied and applied as DC-DC converters in many applications. One of the most demanding applications for LLC converters is data centers. Data centers consume a significant amount of power. According to some estimates\cite{jones2018stop}, data centers around the world consume approximately 200 terawatt-hours of electricity per year, equivalent to the annual electricity consumption of a country like the Netherlands. This high power consumption is primarily due to the growing number of servers and other computing equipment used in data centers and the need for cooling systems. As a result, reducing the power consumption of data centers is a pivotal goal to save costs and reduce their environmental impact. Thus, due to the high power consumption and large-scale server farms, the pursuit of efficient and dense power architecture is ongoing.

This paper addresses the challenges associated with the high winding and core loss in the Integrated Transformer-Inductor (ITL). To overcome these challenges, we propose an improved winding design of the ITL by utilizing idle shielding layers for inductor integration within the matrix transformer. This method offers full printed circuit board (PCB) utilization, where all layers are consumed as winding, resulting in a significant reduction in the winding loss of the ITL. Moreover, we propose an improved core structure of the ITL that offers better flux distribution of the leakage flux within the magnetic core. This method reduces the core loss by more than 50\% compared to the conventional core structure. We demonstrate the effectiveness of our proposed concepts by presenting the design of the ITL used in a high-efficiency, high-power-density 3-kW 400-V-to-48-V LLC module. The proposed converter achieves a peak efficiency of 98.7\% and a power density of 1050 W/in3.