This paper examines existing and future direct current (DC) distribution systems with a wide range of applications in data centers, telecommunication systems, commercial buildings, residential homes, electric vehicles, spacecraft, and aircrafts. DC distribution systems have many advantages and disadvantages over their alternating current (AC) counterparts. There are a few surviving examples of DC distribution systems; among them are the telecommunication systems and data centers that use the low-voltage 48 Vdc systems. However, recently, there has been a move towards higher DC bus voltages. In this paper, a comparative study of different DC distribution architectures and bus structures is presented and voltage level selection is discussed for maximizing system efficiency and reliability, reducing system costs, and increasing the flexibility of the system for future expansion. Furthermore, DC distribution systems are investigated from a safety standpoint and the current global market for these distribution systems is also discussed.

A family of high-voltage-gain dc-dc converters derived from a generalized structure with two stages is introduced in this paper. On the input side, a two-phase interleaved boost stage boosts the dc input voltage to output a modified square wave voltage that feeds the second stage. This output of the interleaved boost stage is rectified and further boosted using a voltage multiplier stage. As a result, a high voltage gain is achieved using the proposed converters. The two-phase interleaved boost stage on the input side makes it possible for the converters to be operated using a single source or two independent sources. If a single source is used, the input current drawn is continuous with a very small ripple. Owing to its generalized structure, the proposed family of converters includes both non-isolated and isolated converters with high voltage gains. The high voltage gain and low-ripple continuous input current make these converters appealing in applications like the integration of renewable sources such as solar, fuel cells, etc., on to a 400V dc bus.