Power supply and distribution systems and operating strategy

A power supply system includes an AC input interface, a DC output interface, and each of a single-conversion power supply path and a multi-conversion power supply path extending between the AC input interface and the DC output interface. Operating the system in a first or standard mode includes conveying electrical power between an AC power supply and an electrical load by way of the single-conversion power supply path. Operation in a second or non-standard operation mode includes conveying the electrical power by way of the multi-conversion power supply path.

TECHNICAL FIELD

The present disclosure relates generally to power supply systems and operating strategies, and more particularly to operating a power supply system so as to switch operation from a first mode supplying power from an electrical power supply to an electrical load via a single-conversion power supply path to a second mode supplying power via a multi-conversion path.

BACKGROUND

A great many different architectures and operating strategies have been proposed for electrical power supply and distribution over the years. In certain environments, it is desirable to have redundant or backup power available in the event of the failure of a primary power supply. One known design includes multiple, fully redundant pathways of essentially identical structure. Such systems provide reliable operation; however, there is always room for improvement.

SUMMARY

Operating a power supply system includes operating the system in a first mode where power is supplied via a single-conversion power supply path from an alternating current (AC) power supply to a direct current (DC) output coupled to an electrical load. Operation of the system can be switched to a second mode responsive to a fault in the single-conversion power supply path, such that electrical power is supplied via a multi-conversion power supply path.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

For purposes of promoting an understanding of the principles of the POWER SUPPLY AND DISTRIBUTION SYSTEMS AND OPERATING STRATEGY, reference will now be made to the examples illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the invention is intended by the illustration and description of certain examples of the invention. In addition, any alterations and/or modifications of the illustrated and/or described embodiment(s) are contemplated as being within the scope of the present invention. Further, any other applications of the principles of the invention, as illustrated and/or described herein, as would normally occur to one skilled in the art to which the invention pertains, are contemplated as being within the scope of the present invention.

Referring toFIG. 1, there is shown an electrically powered computer system10, according to one embodiment. System10may include a plurality of electrically powered computers, such as computer servers having non-volatile and also volatile memory, and depending for successful and continuous operation upon having an uninterrupted supply of electrical power. System10may be equipped with a power supply system11, which may include or be part of an uninterruptible power supply (UPS) system, for continuously supplying electrical power to computers12. A primary power supply14, such as a three-phase alternating current (AC) electrical power grid may be coupled with system11, such as by way of a step down transformer15. A secondary power supply16may be coupled with or part of system11. The terms primary and secondary should not be taken to mean that one of power supply14and power supply16is necessarily used preferentially over the other.

Power supply16might include a conventional electric generator such as a combustion engine-powered generator, but might alternatively include an electrical energy storage medium such as a capacitor bank, batteries, or a different type of power generating mechanism such as a fuel cell, a solar array, an energy storage flywheel or still another. System11may further include an AC input interface18having at least one AC bus20,22structured to connect with AC electrical power supply14. System11may also include a DC output interface24having at least one DC bus42structured to couple with an electrical load such as computers12, to be supplied with electrical power from AC electrical power supply14. While in the illustrated embodiment computers12are shown generally as stand-alone computers or computer servers such as in a data center, it should be appreciated that computers12might be part of computerized machinery, industrial processing equipment, or still another electro-mechanical system sensitive to power interruptions. As will be further apparent from the following description, system11is uniquely configured for reliability and redundancy in power supply while providing reduced costs and complexity as compared with known designs.

System11may further include a single-conversion power supply path30including electrical converter components further described herein, and being structured to convert medium voltage AC electrical current received via bus20or potentially bus22depending upon system architecture, to lower voltage DC electrical power to be supplied to DC output interface24and thus DC bus42in a first operating mode of system11. The medium voltage AC might be from about 700 volts to about 800 volts and the lower voltage DC might be from about 350 volts to about 400 volts, although the present disclosure is not thusly limited.

System11may further include a multi-conversion power supply path32including electrical converter components further described herein, and being structured to convert medium voltage AC electrical power received via AC bus26,28to higher voltage DC electrical power, and to convert higher voltage DC electrical power to lower voltage DC electrical power to be supplied to DC output interface24and thus DC bus42, in a second operating mode of system11. System11may still further include switching elements34and36coupled between output bus42and each of single conversion path30and multi-conversion path32so as to switch electrical connection paths between AC interface input18and DC output interface24and thereby transition system11between the first and second operating modes. Switching elements34and36may include an automated transfer switch (ATS), static transfer switches (STS), or some combination thereof depending upon application and system architecture.

In the illustrated embodiment a first DC bus26is coupled between output bus42and single-conversion supply path30. A second DC bus28is coupled between output bus42and multi-conversion path32. Each of busses26and28receives DC electrical power and current which is produced from AC electrical power supplied to bus20and/or bus22as the case may be. A DC power distribution unit38is coupled with bus26and a second DC power distribution unit38is coupled with bus28. Each of power distribution units38includes a plurality of switches, potentially internal busses, circuit breakers, sensors, or other control and/or monitoring components, and is thereby structured to supply DC electrical power to a plurality of DC feeders, two of which are shown and coupled one with each of power distribution units38. Those skilled in the art will appreciate that each power distribution unit38might supply several or even many DC feeders40, with feeders40each extending in common to a plurality of DC output busses42. Accordingly, while only two DC feeders are shown inFIG. 1, embodiments are contemplated where several DC feeders feed several DC busses from each power distribution unit38.

Switching elements34and36are shown connecting DC feeders40with DC bus42. It will therefore be apparent that DC bus42can be supplied with DC electrical power by way of switches34and36from either of DC feeders40, and thus either of power supply paths30and32. DC bus42may have the form of a remote power panel (RPP) that supplies multiple power supply units (PSU's)44, with each PSU supplying a server computer12. Switching elements34and36each include an active transfer switch (ATS) or a static transfer switch (STS) or some combination thereof. In a practical implementation strategy, switching elements34and36normally close to path30and are open to path32, only transferring to path32if there is a fault in path30as further discussed herein. Power supplied by way of path30in the first mode mentioned above can therefore be understood as a standard mode, whereas operation by way of supplying electrical power via path32can be understood as a non-standard mode, although the present disclosure is not thereby limited.

In the illustrated embodiment, system11may also be equipped with switching elements48and50within input circuitry36in input interface18. Switching elements48and50may be structured so as to selectively connect and/or disconnect power supplies14and16with either of paths30or32. It will therefore be understood that power supply16can supply electrical power to path30or to path32, whereas power supply14can likewise supply electrical power to either of path30or32. Maintenance switches52may also be provided and structured for opening or closing to enable physical and/or electrical disconnection of components of system11from either of supplies14or16.

It will be recalled that power supply path30includes electrical converter components structured to convert medium voltage AC power received via bus20to lower voltage DC electrical power to be supplied to bus42. The terms higher, lower, and medium will be understood herein in a relative sense. In a practical implementation strategy, the electrical converter components can include an AC to DC buck converter, otherwise known as a buck rectifier54. Buck rectifier54can be of a variety of different topologies and constructions, including a passive rectifier such as a thyristor-based passive rectifier. An actively controlled rectifier can also be used. The choice of rectifier may depend upon control and dynamics requirements of critical loads in computers12, such as critical loads where computers12are part of a data center, and thus corresponding to a minimum electrical power supply requirement to avoid data losses. Harmonics requirements or properties of power supply14and also potentially power supply16can also affect selection of a suitable rectifier. Path30will typically have a constant DC voltage as determined by buck rectifier54, thus enabling DC feeder40to have conductor sizes the same as in path30. Those skilled in the art will appreciate instances where a variable voltage necessitates cabling and electrical power supply hardware that accommodates a relatively wide range of voltages. Conversion of electrical power within path30occurs in a total of one conversion stage between AC input interface18and DC output interface24.

It will further be recalled that path32includes electrical converter components structured to convert medium voltage AC power to higher voltage DC power and to convert the higher voltage DC power to lower voltage DC power to be supplied to output interface24and thus DC bus42. To this end, the electrical converter components in path32may include an AC to DC boost converter or boost rectifier56, coupled with a DC to DC converter58, in turn supplying bus28. A battery62may be coupled with components56and58electrically between components56and58and feeds electrical power to bus28by way of a diode64. Electrical power produced by battery62may have a varying voltage, however, the coupling of battery62to bus28by way of converter58allows voltage of electrical power supplied to DC feeder40to be decoupled from the varying voltage of battery62, and thus fixed. A charger60is provided and coupled with bus22, thus structured to charge battery62such as by trickle charging or the like. As discussed above, in certain embodiments a standard or normal operating condition can include supplying power via path30, with switch36open but switch52and switch48or50closed such that charger60electrically connects with power supply14or power supply16, and trickle charges battery62. Charger60may be sized at a reduced capacity compared with rectifier54and rectifier56, such as only about 10% to about 15% of the rectifiers' capacity, and all of the load of PSU44may be carried by path30a majority of the time. This means that combined system efficiency is determined principally by an efficiency of buck rectifier54. Another way to understand these principals is that the path, power supply path30, having only a single electrical converter component will generally determine the overall efficiency of system11since electrical power will predominately be supplied by way of the single conversion path.

Those skilled in the art of redundant and uninterruptible power supply systems will be familiar with the additional costs that typically accompany the addition of components. Additional components, additional connections, additional power supplies and duplications of hardware are typically understood to improve reliability, but of course typically increase costs. What is generally less intuitive is the addition of potential failure modes with the addition or duplication of hardware. In other words, a system that has many different components versus a relatively simpler system with fewer components will often at first impression appear to be more reliable. When a more quantitative consideration of the likelihood of failure of the overall system, as well as likelihood of failure of subcomponents of the system is conducted, however, as in the present instance it becomes apparent that likelihood of failure is not in fact increased or only modestly so, where some of the duplication and addition of hardware is avoided. In the present instance, therefore, a sufficiently reliable system can be provided even though one of the possible power supply paths has fewer components, and in fact lacks the backup power supply of an energy storage device altogether. When a fault occurs in path32, system11can be switched to a backup mode where electrical power is supplied via battery62. Conventional systems might have included multiple power supply paths that were substantially identical, with each including a battery or other energy storage device. In the present instance, it can be seen that only one of paths30and32includes a battery.

It can also be seen fromFIG. 1that a control device72, such as an electronic control module including one or more suitable data processors and a computer memory, is coupled with path30and optionally with other components of system11. Switching elements34and36, or possibly other switches and for that matter any component of system11could be coupled with and in communication with control device72. In one embodiment, control device70actively adjusts switching elements34and36to switch system11between operating modes in response to detection of a fault. In a practical implementation strategy, switching elements will operate to switch system11to the second mode automatically and in a manner transparent to the electrical loads powered thereby. Control device72can autonomously, or with intervention by a human administrator, operate switching elements34and36to return system11to the first operating mode when a fault has cleared. For instance, thyristors or other semiconductor components in switching elements34and36may autonomously operate to electrically disconnect path30and electrically connect path32to operate in the second mode, but require intervention to switch back to the first mode.

Referring now toFIG. 2, there is shown a system110according to another embodiment. System110may have features similar or identical to those of system10except where otherwise indicated and, namely, includes an input interface118and an output interface124, a single-conversion power supply path130and a multi-conversion power supply path132coupled between input interface118and output interface124. Rather than a single DC output bus or remote power panel that feeds multiple PSU's, in system110separate remote power panels142and143are provided which separately supply each PSU144from the voltage feeders corresponding to each power supply path130and132.

Referring toFIG. 3, there is shown yet another embodiment of a system210having features similar but not identical to those in the embodiments discussed above, including an input interface218, an output interface224, a single-conversion power supply path230and a multi-conversion power supply path232. System210further includes switching elements between power supply paths230and232that enable the two paths to be coupled together. The switching elements may include automatic transfer switches (ATS's) or static transfer switches (STS's), or still other switching elements such as mechanical or electromechanical switches that require direct control or even human intervention. In the illustrated embodiment, a first switch235provides for connecting/disconnecting of path230to a bus226, and a second switch237provides for connecting/disconnecting of path232to bus226. A third switch234provides for connecting/disconnecting of path234to a bus228, and a fourth switch provides239provides for connecting/disconnecting of path230to a bus228.

Referring to the drawings generally, but in particular toFIG. 4there is shown a flowchart300illustrating an example operating process according to the present disclosure. The process may START at block310, and advances to block320where system11is operated in a first mode, such as a standard mode where electrical power is supplied via path30in the case of the embodiment ofFIG. 1. From block320, the process may advance to block330where a fault is generated in buck converter54. The fault could be a failure of electrical connectivity, exceeding of a temperature or voltage threshold, or some other occurrence. From block330the process may advance to block340to operate switching elements34and36. From block340the process may advance to block350to operate system11in the second mode, such as a non-standard mode where electrical power is supplied via path32in the case of theFIG. 1embodiment. A control device such as control device72could be monitoring operations and conditions in system11, and command switching back to the first operating mode once a fault is cleared. From block350, the process may advance to END at block360.

The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims.