Patent Publication Number: US-2005134239-A1

Title: Multiple input redundant power system

Description:
FIELD OF THE INVENTION  
      This invention relates generally to the field of power distribution systems. More particularly, this invention relates to power distribution systems that provide redundancy against input power failure.  
     BACKGROUND  
      The need to interface between power sources and loads to be powered has always been basic to applied electricity. The most common power sources in use are AC and DC. Many equipments are designed to operate from one or the other, but other equipment is designed to operate from a plurality of power sources, primarily to provide protection against power source failure.  
      This use of dual power sources is used in the art for systems which must provide reliable operation for extended periods of time. Examples can be found in space flight applications, military systems, and central telecommunications exchanges.  
      Turning now to  FIG. 1 , there is shown an example of a prior art configuration in which power to equipments may be supplied by multiple AC power sources. AC source  120  is routed to the first AC input AC 1  of connected equipments. AC source  125  is routed to the second AC input AC 2  of connected equipments. Connected equipments  105 ,  110 , . . .  115  may be similar or dissimilar equipments depending on user requirements. It is usual that each equipment connected to AC 1  and AC 2  have switchover capability should one power source fail.  
      Turning now to  FIG. 2 , there is shown an example of a prior art configuration in which power to equipment may be supplied by multiple DC power sources. DC source  220  is routed to a first DC input DC 1  of connected equipments. DC source  225  is routed to the second DC input DC 2  of connected equipments. Connected equipments  205 ,  210 , . . .  215  may be similar or dissimilar equipments depending on user requirements. It is usual that each equipment connected to DC 1  and DC 2  have switchover capability should one power source fail.  
      Multiple AC power sources are probably most common, examples being the use of AC with backup UPS and enterprise servers designed for high availability and reliability. Multiple DC power sources are found in telecommunications centers and military applications. By comparison AC-DC power source operation is rare.  
      In the computer and telecommunications industry most sites have access to both AC power and to −48V DC power. If an extended reliability system is installed, an additional AC (or DC) power system may have to be installed. An example of this would be an enterprise server that requires multiple AC power inputs for redundancy.  
     BRIEF SUMMARY  
      The present invention relates generally to dual or multiple power source equipments.  
      In accordance with certain embodiments, an equipment operable to receive and operate on both AC and DC input power is described. It comprises of an AC distribution system which receives and distributes AC input power, a DC distribution system which receives and distributes DC input power, one or more AC/DC converters which receive AC input power from the AC distribution system and produce one or more DC outputs, one or more DC/DC converters operable to receive DC input power from the DC distribution system and to produce one or more DC outputs, and an output combining element operable to couple one or more converter outputs to one or more loads.  
      In accordance with certain other embodiments, a method of operating with dual or multiple input power sources, comprising converting AC input power received by an equipment to one or more AC converted voltages, converting DC input power received by the equipment to one or more second DC converted voltages, and combining the one or more first DC converted voltages and the one or more second DC converted voltages to derive one or more DC equipment voltages.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself however, both as to organization and method of operation, together with objects and advantages thereof, may be best understood by reference to the following detailed description of the invention, which describes certain exemplary embodiments of the invention, taken in conjunction with the accompanying drawings in which:  
       FIG. 1  is an exemplary illustration of a standard AC-AC application according to the prior art.  
       FIG. 2  is an exemplary illustration of a standard DC-DC application according to the prior art.  
       FIG. 3  is an exemplary illustration of an AC-DC application for a system in accordance with certain embodiments of the present invention.  
       FIG. 4  is an exemplary illustration of the input power section of equipment designed for AC-DC in accordance with certain embodiments of the present invention.  
       FIG. 5  is a further exemplary illustration of an AC-DC application for a system in accordance with certain embodiments of the present invention.  
       FIG. 6  is an exemplary illustration of a system utilizing equipments powered by AC/DC sources in accordance with certain embodiments of the present invention.  
    
    
     DETAILED DESCRIPTION  
      The present invention relates generally to multiple power source equipments, systems, and methods of using thereof. Objects, advantages and features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the invention.  
      A method and structure for achieving power source redundancy is presented in accordance with certain embodiments of the present invention. This is a feature of the present invention which allows AC-DC equipments to be utilized, thereby saving additional infrastructure costs and time.  
      A method and structure for designing the input power section of AC-DC powered equipment is presented in accordance with certain other embodiments of the present invention. This is a feature of the present invention, allowing input power sections similar to both AC-AC and DC-DC equipments to be combined.  
      A method and structure for extending the power input sections to include load-sharing converters in accordance with certain embodiments of the present invention. This is a feature of the present invention, and allows sophisticated power conversions to accept AC-DC input power.  
      Many variations, equivalents and permutations of these illustrative exemplary embodiments of the invention will occur to those skilled in the art upon consideration of the description that follows. The particular examples above should not be considered to define the scope of the invention. For example, a UPS may be utilized either in place of or as an adjunct to AC power. Another example of a variation which does not depart from the spirit of the invention would be placing the AC-DC powered equipment in systems containing other equipment powered differently, such as AC, DC, AC-AC, and DC-DC. A further example would be the use of intelligent power switching in systems as a way to control power changeover timing.  
      While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail specific embodiments, with the understanding that the present disclosure is to be considered as an example of the principles of the invention and not intended to limit the invention to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings.  
      For purposes of this document, the exact mechanical and electrical parameters of equipments are unimportant to an understanding of the invention, and many different types of electrical and mechanical components may be utilized without departing from the spirit of the invention. An example is that the required electrical capacity of converters will depend upon the application at hand and may vary between otherwise similar equipments in the same system. This document uses generalized descriptions by way of example only. Many variations for these constituent items are possible without departing from the spirit and scope of the invention.  
       FIG. 3  is an illustration of a system implementation for AC and DC multiple power sources in accordance with certain embodiments of the present invention. An AC source  320  and a DC source  325  are routed to the AC and DC inputs respectively of system equipments  305 ,  310 , . . .  315 . The AC source may be in general of any voltage range, be single phase or 3-phase, and of any number of wires. In general the AC source specifications are determined by system requirements. Typical AC characteristics are single-phase, 3-wire (Delta) or 4-wire (Wye) three phase, with any of these single or three phase configurations having a safety ground, 115/220 VAC and 240 to 480 VAC, by way of example and not limitation. Note that utilizing an existing AC power source may negate the need to increase infrastructure by adding an additional DC power system for independent power.  
      The present invention envisions diverse AC sources such as substation feeds, inverters, motor-generator sets, and uninterruptible power systems, without departing from the spirit and scope of the invention. In addition the AC source may consist of a multiplicity of AC sources, such that (not shown) a first equipment may be connected to one source and a second equipment connected to the same or a different AC source. It is also clear that the electrical characteristics of system equipments  305  . . .  315  are operationally compatible with the selected AC source(s).  
      FIG. 4  is an exemplary illustration of the input power section of equipment designed for AC-DC in accordance with certain embodiments of the present invention. Equipment  500  may be any one of the  305 ,  310  . . .  315  equipments, wherein the power conversion section is depicted as power distribution block  600 , converter block  700 , and DC output block  800 . Output block  800  may comprise active or passive circuitry, based upon system requirements. Output block  800  may include communications with one or more processors internal or external to the output block.  
      AC source  405  is routed to power distribution block  600 . Power distribution block  600  distributes AC source  405  to the AC power inputs of AC/DC converters  705 ,  710  . . .  715 . This is illustrated by AC distribution path  605 . The number of AC/DC converters  705 ,  710  . . .  715  needed depends on the internal design requirements of equipment  500 . Conditioning to include filtering, fusing, step-up, step-down, and regulation of AC source  405  may be utilized internal or external to equipment  500  without departing from the scope of the invention.  
      DC source  410  is routed to power distribution block  600 . Power distribution block  600  distributes DC source  405  to the DC power inputs of DC/DC converters  720 ,  725  . . .  730 . This is illustrated by DC distribution path  610 . The number of DC/DC converters  720 ,  725  . . .  730  depends on the internal design requirements of equipment  500 . Conditioning to include filtering, fusing, and regulation of DC source  410  may be utilized internal or external to equipment  500  without departing from the scope of the invention.  
      The DC outputs of AC/DC converters  705 ,  710  . . .  715  and DC/DC converters  720 ,  725  . . .  730  are combined by DC distribution element  805 . DC distribution  805  may consist of a simple diode OR&#39;ing arrangement (diode combining); it may consist of an active combining arrangement (not shown); or it may consist of a feedback arrangement with individual converters for load management and control with or without internal or external processor control. Such variations are within the scope of the present invention, and other methods of integrating the converters with each other and with the output distribution for power control purposes are allowable without departing from the spirit of the invention.  
      The output of DC distribution  805  is final DC output  900 . The value of DC output  900  will be determined by system requirements internal to equipment  500 . By way of example, a common requirement for DC output  900  is +48 VDC for enterprise servers and other types of computing and telecom equipment.  
      It is a feature consistent with certain embodiments of the present invention that the AC input converter section, consisting of AC/DC converters  705 ,  710  . . .  715 , may employ any method of redundancy to achieve higher reliability for equipment  500 .  
      It is a further feature consistent with certain embodiments of the present invention that the DC input converter section, consisting of DC/DC converters  720 ,  725  . . .  730 , may employ any method of redundancy to achieve higher reliability for equipment  500 .  
      It is a further feature consistent with certain embodiments of the present invention that both the AC input converter section, consisting of AC/DC converters  705 ,  710  . . .  715 , and the DC input converter section, consisting of DC/DC converters  720 ,  725  . . .  730 , may employ any method of separate or joint redundancy to achieve higher reliability for equipment  500 . Examples of such redundancy would be load sharing between converters, and standby hot converters (N+1 approach).  
      It is also an advantage consistent with certain embodiments of the present invention that DC source  410 , which commonly exists in, for example, telecommunications facilities, may be utilized in lieu of installing facility infrastructure necessary to provide a secondary AC input to achieve higher reliability of the overall system. It is another advantage consistent with certain embodiments of the present invention that AC source  405 , which commonly exists in facilities, may be utilized in lieu of installing facility infrastructure necessary to provide a secondary DC input to achieve higher reliability of the overall system. Moreover, in certain embodiments it is a further advantage of the present invention that a tightly regulated DC output may be obtained with the high reliability operation from both AC and DC, as described above.  
      It is a characteristic that consistent with certain embodiments a power system is described which is inline and achieves the intent of the UPTime Institute Certification guideline for High Availability systems.  
      An advantage consistent with certain embodiments of the present invention is that, within a facility system, the AC and DC power sources applied to any particular equipment may be of different origins from those applied to other equipments in the system. This is of benefit if different sources are limited in power or located in different facility areas.  
      FIG. 5  is an exemplary illustration  400  of the input power section of equipment designed for AC-DC in accordance with certain embodiments of the present invention. In this system, equipment  500  may be any one of the  305 ,  310  . . .  315  equipments, wherein the power conversion section is depicted as power distribution block  600 , converter block  700 , and DC output blocks  800 ,  830  . . .  860 . Output blocks  800 ,  830  . . .  860  may comprise active or passive circuitry depending on system requirements. Output blocks  800 ,  830  . . .  860  may include communications with one or more processors internal or external to the output blocks.  
      AC source  405  is routed to power distribution block  600 . Power distribution block  600  distributes AC source  405  to the AC power inputs of AC/DC converters  705 ,  715  . . .  725 . This is illustrated by AC distribution path  605  which routes AC source  405  to AC/DC converter inputs  709 ,  719 , and  729 . The number of AC/DC converters  705 ,  710  . . .  715  needed depends on the internal design requirements of equipment  500 . Conditioning to include filtering, fusing, step-up, step-down, and regulation of AC source  405  may be utilized internal or external to equipment  500  without departing from the spirit and scope of the invention.  
      DC source  410  is routed to power distribution block  600 . Power distribution block  600  distributes DC source  405  to the DC power inputs of DC/DC converters  735 ,  745  . . .  755 . This is illustrated by DC distribution path  610  which routes DC source  410  to DC/DC converter inputs  739 ,  749 , and  759 . The number of DC/DC converters  735 ,  745  . . .  755  depends on the internal design requirements of equipment  500 . Conditioning to include filtering, fusing, and regulation of DC source  410  may be utilized internal or external to equipment  500  without departing from the spirit and scope of the invention.  
      The DC outputs of AC/DC converters  705 ,  715  . . .  725  and DC/DC converters  735 ,  745  . . .  755  are combined by DC distribution elements  805 ,  835 , and  865 . DC distribution elements  805 ,  835 , and  865  may consist of a simple diode OR&#39;ing arrangements (diode combining), active combining arrangements (not shown), or it may consist of feedback arrangements between individual converters for load management and control, with or without internal or external processor control to the converters. Connections between converters are shown by the interconnection of ports  710 ,  720  . . .  730  and  740 ,  750  . . .  760 . Any combination of these ports may be utilized. Details of signal flow formats between ports will depend on system requirements. Feedback for load management and control may also be implemented from the DC outputs back to the converters. Voltage detectors/monitors  810 ,  840 , and  870  serve to relay information relative to the output powers  900 ,  905  . . .  910  to the converters, via ports  711 ,  721  . . .  731  and  741 ,  751  . . .  761 . Details of signal flow formats between ports and voltage detectors/monitors depends on system requirements. Such variations are within the spirit and scope of the present invention, and other methods of integrating the converters with each other and with the output distribution for power control purposes are allowable without departing from the spirit and scope of the invention.  
      Each converter may be capable of multiple outputs. Such outputs may provide a multiplicity of voltages, or supplemental current capability. AC/DC converter  705  may have multiple outputs  706 ,  707  . . .  708 . AC/DC converter  715  may have multiple outputs  716 ,  717  . . .  718 . AC/DC converter  725  may have multiple outputs  726 ,  727  . . .  728 . DC/DC converter  735  may have multiple outputs  736 ,  737  . . .  738 . DC/DC converter  745  may have multiple outputs  746 ,  747  . . .  748 . DC/DC converter  755  may have multiple outputs  756 ,  757  . . .  758 . For example, multiple outputs may consist of +5 VDC, −12 VDC and +12 VDC, and single outputs may be +5 VDC or −24 VDC. Each converter may have multiple or single outputs. Each converter may be the same as or different from any other converter, in terms of its voltage outputs.  
      The multiplicity of voltage outputs available are routed to DC output blocks  800 ,  830  . . .  860 . These output blocks serve to combine similar voltages into a single output. Output block  800  receives converter outputs  706 ,  716  . . .  726  and  736 ,  746  . . . 756  as inputs. These inputs are combined by DC distribution element  805  to provide output power  900 . Output block  830  receives converter outputs  707 ,  717  . . .  727  and  737 ,  747  . . .  757  as inputs. These inputs are combined by DC distribution element  835  to provide output power  905 . Output block  860  receives converter outputs  708 ,  718  . . .  726  and  738 ,  748  . . .  758  as inputs. These inputs are combined by DC distribution element  865  to provide output power  910 .  
      It is a feature consistent with certain embodiments of the present invention that any number of converters may contribute to a specific output voltage, and there may be any number of specific output voltages. For example, the outputs may be +5, +12, −12, +15, −24 and +3.3 VDC, wherein 2 converters may contribute to +5, 4 converters may contribute to +12, 5 converters may contribute to −12, 2 converters may contribute to −24, and 3 converters may contribute to +3.3 VDC. The control of each output voltage may be accomplished within a given converter, by a combination of converters sharing feedback, by feedback from the output back to one or more converters, or any combination thereof. Thus, in certain embodiments an advantage is gained with respect to loss of power, either by loss of source power or converter failure, because multiple power paths can exist for a given output power. Load sharing and partitioning between active converters is achievable, depending on system requirements. DC source  410  is also routed to output blocks  800 ,  830  . . .  860  in the event that output power  900 ,  905  . . .  910  is close in voltage to DC source  410  such that the DC source may be substituted as a particular power output should the normally utilized converters fail.  
      The value of the DC outputs will be determined by system requirements internal to equipment  500 . By way of example and not limitation, a common requirement for a DC power output is +48 VDC for enterprise servers and other types of computing and telecom equipment.  
      It is a feature consistent with certain embodiments of the present invention that the AC input converter section, consisting of AC/DC converters  705 ,  715  . . .  725 , may employ any method of redundancy to achieve higher reliability for equipment  500 .  
      It is a further feature consistent with certain embodiments of the present invention that the DC input converter section, consisting of DC/DC converters  735 ,  745  . . .  755 , may employ any method of redundancy to achieve higher reliability for equipment  500 .  
      It is a further feature consistent with certain embodiments of the present invention that both the AC input converter section, consisting of AC/DC converters  705 ,  715  . . .  725 , and the DC input converter section, consisting of DC/DC converters  735 ,  745  . . .  755 , may employ any method of separate or joint redundancy to achieve higher reliability for equipment  500 .  
      DC source  410 , which commonly exists in, for example, telecommunications facilities, may be utilized in lieu of installing facility infrastructure necessary to provide a secondary AC input to achieve higher reliability of the overall system in certain embodiments. AC source  405 , which commonly exists in facilities, may be utilized in lieu of installing facility infrastructure necessary to provide a secondary DC input to achieve higher reliability of the overall system in certain embodiments. A tightly regulated DC output may be obtained with high reliability operation from both AC and DC power inputs, as described above.  
      It is a characteristic of the present invention that a power system is described which is inline and achieves the intent of the UPTime Institute Certification guideline for High Availability systems.  
      Consistent with certain embodiments, within a facility system the AC and DC power sources applied to any particular equipment may be of different origins from those applied to other equipments in the system. This is of benefit if different sources are limited in power or located in different facility areas.  
      Referring to  FIG. 6 , a system  1000  operating with multiple AC/DC powered equipments and multiple AC and multiple DC power sources is presented. AC power sources  1035 ,  1040  . . .  1045  may be any sort of AC source such as single phase or 3-phase, any voltage such as 110 or 220 VAC, and any number of wires, as described previously. These AC sources are selectively routed to AC source inputs  405  of equipments  1 ,  2  . . . N as required by system requirements. In other words, AC source input  405  of each equipment may be connected to any of the AC sources  1035 ,  1040  . . .  1045 . As an example, constituent parts of the total system may be in various physical locations and the source of AC feeds to these separated equipments may be different. Schematically  1005 ,  1015  . . .  1025  are decision points at which a specific AC source  1035 ,  1040  . . .  1045  is connected to a specific equipment  1 ,  2  . . . N. Any AC source may be connected to any equipment AC source input. DC power sources  1050 ,  1055  . . .  1060  may be any sort of DC source such as +48, −48, + 5  VDC as described previously. These DC sources are selectively routed to DC source inputs  410  of equipments  1 ,  2  . . . N as required by system requirements. In other words, DC source input  410  of each equipment may be connected to any of the DC sources  1050 ,  1055  . . .  1060 . As an example, constituent parts of the total system may be in various physical locations and the source of DC feeds to these separated equipments may be different. Schematically  1010 ,  1020  . . .  1030  are decision points at which a specific DC source  1050 ,  1055  . . .  1060  is connected to a specific equipment  1 ,  2  . . . N. Any DC source may be connected to any equipment DC source input. The system described allows any available AC source to be connected to any AC equipment input, and allows any available DC source to be connected to any DC equipment input. Equipments may be co-located or physically separate depending on requirements.  
      Those skilled in the art will appreciate that many other circuit and system configurations can be readily devised to accomplish the desired end without departing from the spirit of the present invention.  
      While the invention has been described in conjunction with specific embodiments, it is evident that many alternatives, modifications, permutations and variations will become apparent to those of ordinary skill in the art in light of the foregoing description. By way of example and not limitation, the overall system may contain any combination of AC/AC, AC/DC, and DC/DC power input equipments without departing from the invention. Many other variations are also possible. Accordingly, it is intended that the present invention embrace all such alternatives, modifications and variations as fall within the scope of the appended claims.