Dual-voltage output power supply system toward parallel use of 380Vdc and 48Vdc

The amount of energy consumed by data centers and telecom buildings is increasing annually due to the buildup and high-density arrangement of ICT equipment, which is needed to handle the rapid rise in traffic brought on by the spread of smartphones and advances in the Internet usage environment. The NTT Group, whose business activities are centered about ICT services, uses approximately 8.5 billion kWh of power a year. This figure corresponds to about 1% of electric power sales in Japan. Therefore the promotion of energy-saving measures has become an important issue in terms of both an environmental problem and the need to reduce costs. The NTT Group is therefore committed to reducing the amount of power that it uses. This is reflected by its decision to introduce on a large scale a high-voltage direct-current (HVDC) power supply system, which is a next-generation power supply architecture that it has been researching and developing and evaluating in field trials. In this paper we introduce a power supply system that outputs both DC -48V as a supply for legacy communications equipment and DC 380V for HVDC supply systems, then assess the space-saving qualities of the new supply system.