Design of an 99%-efficient, 5kW, phase-shift PWM DC-DC converter for telecom applications

In the last decade power electronic research focused on the power density maximization mainly to reduce initial systems costs [1]. In the field of data centers and telecom applications, the costs for powering and cooling exceed the purchasing cost in less than 2 years [2]. That causes the changing driving forces in the development of new power supplies to efficiency, while the power density should stay on a high level. 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 and efficient power conversion, a compact design and the constant operation frequency allows a simple control and EMI design. The development of the converter with respect to high efficiency has a lot of degrees of freedom. An optimization procedure based on comprehensive analytical models leads to the optimal parameters (e.g. switching frequency, switching devices in parallel and transformer design) for the most efficient design. In this paper a 5kW, 400V–48⋖56V phase-shift PWM converter with LC-output filter is designed for highest efficiency (η ≥99%) with a volume limitation and the consideration of the part-load efficiency. The components dependency as well as the optimal design will be explained. The realized prototype design reaches a calculated efficiency of η = 99.2% under full load condition and a power density of ρ = 36W/in3 (2.2 kW/liter).