An Optimized 5 kW, 147 W/in3 Telecom Phase-Shift DC-DC Converter with Magnetically Integrated Current Doubler

In the last decade there has been a tremendous growth in the number of data centers due to the increasing demand for internet services. At the same time, the cost for energy and materials have increased because of reducing resources and increased demand. That has caused a change in the driving forces for new power supply development, with more consideration on power density and efficiency. The commonly used DC-DC converter in the power supply unit (PSU) for data centers and telecom applications are full bridge phase-shift converters since they meet the demands of high power levels and concurrently efficient power conversion as well as a compact design. The constant operating frequency allows a simple control and EMI design. To develop a new converter with higher power density and/or high efficiency the designer has a lot of degrees of freedom. An optimization procedure, based on comprehensive analytical models, has been developed and leads to the optimal parameters (e.g. switching frequency or transformer design) to achieve the most compact and/or efficient design. In this paper an volume optimized 400 V/48 V phase-shift DC-DC converter with current doubler rectifier based on analytical models is constructed. The power density of the converter is increased by integrating the output inductors in the transformers core. The intrinsic voltage ringing of the rectifier diodes is damped by a lossless magnetic snubber, which feeds ringing energy to the output. Experimental results prove the theoretical analytical models and the design procedure. The 5kW DC-DC converter prototype had a power density of 9 kW/liter (147Win(3)) and a maximum efficiency of 94.75%.