Commercial and industrial applications getting ready for direct-current power distribution

This paper describes design trends in several classes of power-electronic appliances that will increase the appeal for distributing DC power in buildings. In the commercial sector information technology (IT) power conversion architectures are moving from multi to single-voltage supplies, initially 12 Vdc and evolving toward 48 Vdc. These changes apply to both data processing and Internet server equipment. For motor loads, adjustable speed drives (ASDs) are increasingly common in industrial settings as well as modern commercial buildings. Since these motor drives operate with a 200 to 700 V dc-link they are good candidates for direct DC power. In fact, drives are also beginning to appear in single-phase residential appliances and offer opportunities for direct integration with DC from photovoltaic systems or fuel cells. This paper reviews basic design considerations and energy savings potential for operating these appliances directly from DC distribution.