Flexible implementation of distributed DC power

#The present invention relates generally to DC power distribution systems and more specifically to fault tolerant DC power distribution systems for computer and other electronic systems.

#A common technique for the distribution of DC power to large, multi-component computer systems or electronics systems is to provide a common power rail. (The term "rail," as used herein, includes both the hot path and return path.) This rail can be energized with DC power with a minimum number of connections to a power source yet can supply power to as few or as many components or units as the system requires. The impact of any interruption of the power to the rail during operation, however, can be substantial.

#Various systems have been developed to render the power supplied through a common rail more reliable or fault tolerant. The power distribution system can include batteries. In the event of an interruption in the supply from the power source, the batteries can energize the rail for a sufficient period of time to permit an orderly shutdown or even to maintain reduced operation for a limited period of time. Redundant rails may be provided, each of which is separately powered, either from a separate power source or from batteries. In the event of an interruption of the power supply on one rail, power can be drawn from the other rail. Finally, even in a single rail system, that rail may be provided with power from more than one source. Thus, that rail will remain energized even should one of the power sources fail.

#FIG. 1 shows the preferred embodiment of the invention, configured for two AC power sources and two pairs of batteries (the "2N Configuration").

#FIG. 2 shows the preferred embodiment of the invention, configured for only one AC power source and a bank of up to four batteries (the "N+1 Configuration").

#FIG. 3 is a top and rear view of the PDUs of the preferred embodiment in the 2N configuration.

#In its preferred embodiment, the system may provide either for two power supplies mirrored against two other power supplies (the "2N configuration") or for two power supplies with lesser levels of redundancy (the "N+1 configuration").

#FIG. 1 illustrates the 2N configuration of the preferred embodiment. As seen in FIG. 1, the preferred embodiment of the invention includes a power cage 1 constructed to provide DC power to two independent power rails, rail A 2 and rail B 3, that, in turn, provide the power to the customer replaceable units ("CRUs") of, for example, a computer system represented by the logic loads 1-N 4. (For clarity, the return path connections are not shown.) The power cage has two slots, slot A 5 and slot B 6.

#For the 2N configuration, a single PDU 7, 8 is installed into each of slot A and slot B. The PDU design may include techniques for EMI filtering and transient energy suppression as well as AC breaker protection. Each PDU is connected to a source of AC power by a conventional power cord and plug 9 and provides power to two 1500 watt DC bulk power supplies, arranged in parallel. The PDU in slot A feeds "Bulk Supply A" 10 and "Bulk Supply B" 11; the PDU in slot B feeds "Bulk Supply C" 12 and "Bulk Supply D" 13. Bulk power supplies A and B are then connected at point 14 to rail A. Bulk power supplies C and D are connected to bus bar switch 15 (shown in phantom) at point 16. In the 2N configuration, the bus bar switch is set to position 2 (shown in phantom) which thereby connects bulk power supplies C and D to rail B at point 17.