Uninterruptible power supply system and method utilizing interconnected power routing units

Abstract

An uninterruptible power supply system and method utilizing interconnected power routing units is provided. A system includes a plurality of power routing units. Each of the power routing units includes a first AC port, a second AC port, and a static switch configured to couple and decouple the first AC port and the second AC port. Each of the power routing units further includes a DC port and a bidirectional converter circuit coupled between the second AC port and the DC port. The DC ports of the power routing units are collectively coupled to a DC bus, and the system further includes a control circuit configured to control the power routing units to provide power transfer between at least two of the power routing units via the DC bus.

Description

[0001] This application is a divisional application of the application filed on April 20, 2017, with application number 201780034218.0 and entitled "Uninterruptible power supply system and method utilizing interconnected power routing units". Technical Field

[0002] The subject matter of this invention relates to power distribution systems and methods, and more specifically, to uninterruptible power supply (UPS) systems and methods. Background Technology

[0003] UPS systems are typically used in equipment such as data centers, medical centers, and industrial facilities. UPS systems can be used in such facilities to provide backup power to maintain operation in the event of a major utility power failure. These UPS systems typically have an "online" configuration, which includes rectifiers and inverters coupled via a DC (DC) link that is also coupled to an auxiliary power source, such as a battery, fuel cell, or other energy storage device. Other UPS systems may use a standby online interactive architecture or other architectures.

[0004] UPS systems can be implemented using modular components. For example, a UPS system can comprise multiple UPS modules, each of which may include, for example, a rectifier, an inverter, and a DC / DC converter for interface connection to a battery. The UPS modules, along with control and interface circuitry such as bypass switches, can be mounted together in a common rack. UPS modules can be designed to operate in parallel to provide scalable power capacity; for example, the modules may be commonly coupled to an AC source, a DC source (e.g., a battery), and / or a load. An example of such modular UPS components is Eaton. ® The Power XPert 9395 UPS (described at http: / / powerquality.eaton.com) can be configured to include two or more uninterruptible power modules (UPMs), each UPM containing a double-conversion UPS circuit that includes a rectifier, an inverter, and a battery converter coupled to a common DC bus. Other modular UPS architectures are described in U.S. Patent Application Serial No. 13 / 936,741 (Attorney General's No. 9060-321), filed July 8, 2013, entitled "UPS Systems and Methods Using Variable Configuration Modules," which is incorporated herein by reference. Summary of the Invention

[0005] Some embodiments of the inventive subject matter provide a system including a plurality of power routing units. Each of the power routing units includes a first AC port, a second AC port, and a static switch configured to couple and decouple the first AC port and the second AC port. Each of the power routing units further includes a DC port and a bidirectional converter circuit coupled between the second AC port and the DC port. The DC ports of the power routing units are collectively coupled to a DC bus, and the system further includes a control circuit configured to control the power routing units to provide power transfer between at least two of the power routing units via the DC bus.

[0006] In some embodiments, the first AC port of the first power routing unit can be coupled to a first AC power source, and the first AC port of the second power routing unit can be coupled to a second AC power source. The control circuit can be configured to cause the second power routing unit to provide power to the first power routing unit via the DC bus in response to a failure of the first AC power source and / or a failure of the static switch of the first power routing unit.

[0007] In other embodiments, the second AC port of the first power routing unit can be coupled to a first load, and the second AC port of the second power routing unit can be coupled to a second load. The second power routing unit can be configured to provide power to the first load from the second AC power source via the static switch and the converter circuit of the second power routing unit, the DC bus, and the converter circuit of the first power routing unit.

[0008] In some embodiments, the control circuit can be configured to control the power routing units to provide power to the first power routing unit from the second power routing unit and a third power routing unit via the DC bus. The control circuit can be configured to operate the second power routing unit to regulate a voltage on the DC bus and to operate the third power routing unit as a regulated current source to provide power to the first power routing unit. The second AC ports of the first, second, and third power routing units can be collectively coupled to an AC power source, and the first AC ports of the first, second, and third power routing units can be coupled to respective first, second, and third loads.

[0009] According to other embodiments, the first AC port of the first and second power routing units can be collectively coupled to an AC power source, the second AC ports of the first and second power routing units can be coupled to respective first and second loads, and the control circuit can be configured to simultaneously provide power from the AC power source to the first load via the static switch of the first power routing unit and to the second load via the converter circuit of the first and second power routing units. The control circuit can be configured to operate both of the power routing units to provide a multi-converter power chain from the AC source to a load coupled to one of the two power routing units.

[0010] In some embodiments, the control circuit can include a local control circuit in a respective one of the power routing units, and a master controller configured to control the local control circuits of the power routing units.

[0011] In some embodiments, the control circuit can include a respective local control circuit positioned in the power routing units, and the respective local control circuit is configured to operate the associated converter circuit to selectively provide a first mode in which the converter circuit regulates a voltage on the DC bus and a second mode in which the converter circuit provides a regulated current to the DC bus.

[0012] In some embodiments, the system can further include a DC power source coupled to the DC bus.

[0013] In other embodiments, the static switch can be a first static switch, and each of the power routing units can further include a third AC port and a second static switch configured to couple and decouple the third AC port and the second AC port.

[0014] Other embodiments provide a power routing unit including a first AC port configured to be coupled to an external AC source, a second AC port configured to be coupled to an external load, and a static switch configured to couple and decouple the first AC port and the second AC port. The power routing unit further includes a DC port configured to be coupled to an external DC bus, a bidirectional converter coupled between the second AC port and the DC port, and a control circuit configured to control the static switch and the converter circuit to selectively provide a first mode in which the converter regulates a voltage on the external DC bus and a second mode in which the converter provides a regulated current to the external DC bus.

[0015] Other embodiments provide methods including providing a plurality of power routing units, each power routing unit including a first AC port, a second AC port, a static switch configured to couple and decouple the first AC port and the second AC port, a DC port, and a bidirectional converter circuit coupled between the second AC port and the DC port. The methods further include collectively coupling the DC ports of the power routing units to a DC bus and controlling the power routing units to provide power transfer between at least two of the power routing units via the DC bus. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 FIG. 1 is a schematic diagram illustrating an uninterruptible power supply (UPS) system utilizing interconnected power routing units according to some embodiments.

[0017] Figure 2 FIG. 2 is a schematic diagram illustrating an example of a circuit configuration of a power routing unit in Figure 1

[0018] Figure 3 FIG. 3 is a schematic diagram illustrating a static UPS system according to some embodiments.

[0019] Figure 4 FIG. 4 is a schematic diagram illustrating a captive UPS system according to some embodiments.

[0020] Figure 5 and Figure 6 FIG. 5 is a schematic diagram illustrating a UPS system having reconfigurable operating modes utilizing power routing units according to some embodiments.

[0021] Figure 7 FIG. 6 is a schematic diagram illustrating a control architecture for DC bus control in a UPS system according to some embodiments.

[0022] Figure 8 FIG. 7 is a schematic diagram illustrating application of the control architecture of Figure 7

[0023] Figure 9 FIG. 8 is a schematic diagram illustrating a UPS system utilizing power routing units having multiple static switches according to some embodiments. DETAILED DESCRIPTION

[0024] ​​Specific exemplary embodiments of the subject matter of the present application will now be described with reference to the following drawings. The subject matter of the present application may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth in this disclosure, but rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter of the present application to those skilled in the art. In the drawings, like reference numerals refer to like items throughout. It will be understood that when one item is referred to as being "connected" or "coupled" to another item, it can be directly connected or coupled to the other item or intervening items can be present. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the subject matter of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "includes", "comprises", "including" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0026] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this subject matter belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an overly legal sense unless expressly so defined herein.

[0027] Figure 1 A system according to some embodiments of the subject matter of the present application is shown. The system includes a plurality of power routing units 110, which are collectively connected to an external DC bus 120. Each of the power routing units 110 includes at least one static switch 112, which is connected between an AC input port 111 and an AC output port 113 of the power routing unit 110. Each power routing unit 110 further includes at least one bidirectional converter circuit 114, which is coupled between the AC output port 113 and a DC port 115, which is coupled to the DC bus 120. The converter circuit 114 is configured to support power flow in both directions, thereby supporting a plurality of different configurations of the power routing unit 110, as described in more detail with reference to Figures 3 to 9 which is explained in more detail.

[0028] It will be appreciated that the power routing unit 110 can be implemented using any of a large number of different types of circuitry. For example, the static switch 112 can be implemented using any of a number of different types of solid state switching devices, such as SCRs or power MOSFETs. The converter circuit 114 can be implemented using different types of converter architectures, such as a bridge converter circuit. These circuits can use any of a number of different types of solid state switching devices, such as IGBTs or power MOSFETs. The static switch 112 and the converter 114 can be controlled using any of a number of different analog and / or digital control circuits, including but not limited to microcontroller-based or other types of digital control circuits.

[0029] Figure 2 An example of a circuit configuration for a power routing unit is shown according to other embodiments. The power routing unit 210 includes a three-phase static switch 212 implemented using anti-parallel connected pairs of silicon controlled rectifiers (SCRs). The static switch 212 is coupled between AC input ports 211 and AC output ports 213 of the power routing unit. The power routing unit 210 further includes a three-phase bridge circuit 214 including transistors Q (e.g., IGBTs or power MOSFETs) coupled for respective half-bridge pairs of respective phases and respective inductors L for respective phases. The bridge circuit 214 is coupled between the AC output ports 213 and a DC port 215. The bridge circuit 214 can further include one or more DC link capacitors C coupled to the DC port 215, which can provide energy storage to support maintenance of a DC bus voltage connected to the DC port 215, although it will be appreciated that such capacitance can be provided or supplemented by capacitors located external to the power routing unit 210. A control circuit 216 is configured to control the static switch 212 and the bridge circuit 214 to provide various modes of operation supporting various power flows between the AC ports 211, 213 and the DC port 215. The control circuit 215 can be implemented using any of a number of different analog and / or digital circuits, including for example, a control circuit employing data processing circuitry, such as a microcontroller or microprocessor.

[0030] According to some embodiments, power routing units, along with the above Figure 1 and Figure 2 The described circuits can be used to provide a number of different uninterruptible power supply (UPS) systems. For example, reference is made to Figure 3The UPS system may include first and second power routing units 310a and 310b, each of which includes a static switch 312, a converter circuit 314, and a control circuit 316 for controlling the static switch 312 and the converter circuit 314. The corresponding first and second sources 10a and 10b are coupled to the AC input port of a corresponding power routing unit 310a and 310b, and the corresponding loads 20a and 20b are connected to the AC output port of a corresponding power routing unit 310a and 310b. The DC ports of the power routing units 310a and 310b are commonly connected to a DC bus 320.

[0031] Figure 3 The arrangement shown can be implemented as a battery-free static UPS system. Specifically, under normal operating conditions, power can be supplied from the respective sources of the first and second AC sources 10a and 10b via static switches of the respective units of the first and second power routing units 310a and 310b to the first and second loads 20a and 20b. In response to, for example, a failure of the first AC source 10a, power can be supplied from the second power source 20b via the converter circuit 314 of the second power routing unit 310b, the DC bus 320, and the converter circuit 314 of the first power routing unit 310a to the first load 20a. Similarly, in response to a failure of the second AC source 10b, power can be supplied from the first AC source 10a via the converter circuit 314 of the first power routing unit 310a, the DC bus 320, and the converter circuit 314 of the second power routing unit 310b to the second load 20b.

[0032] like Figure 3 As further shown, DC power supply 15 can be coupled to DC bus 320. DC power supply 15 may include, for example, a battery, a fuel cell generator, a photovoltaic source, etc. In some embodiments, DC power supply 15 can be used to provide additional backup power in the event of a failure of any one or both of AC sources 10a and 10b. In other embodiments, DC power supply 15 can be used, for example, to support power sharing operations, such as peak shaving operations, which use DC power supply 15 to provide supplemental power to any one or both of AC sources 10a and 10b during peak rates.

[0033] Figure 4Another UPS system arrangement is shown, which advantageously uses the power routing units described above. The AC outputs of first, second and third power routing units 310a, 310b, 310c are connected to respective loads 20a, 20b, 20c, whose AC input ports are collectively connected to the AC source 10 and whose DC ports are collectively coupled to the DC bus 320. Each of the first, second and third power routing units 310a, 310b, 310c contains a static switch 312, a converter circuit 314, and a control circuit 316 that controls the static switch 312 and the converter circuit 314. The master controller 30 is configured to communicate with the control circuits 316 to provide monitoring and management control.

[0034] The power routing units 310a, 310b, 310c can operate to provide backup power delivery options. For example, under normal conditions, the power routing units 310a, 310b, 310c can provide power to their respective loads 20a, 20b, 20c via their static switches 312. In response to, for example, a failure of the static switch 312 of the first power routing unit 310a, the second and third power routing units 310b, 310c can provide power to the first load 20a via the DC bus 320. Such operation can be controlled by the master controller 330, for example, the master controller 330 can receive status information from the first power routing unit 310a indicating a failure of its static switch 312, and can command the first power routing unit 310a to operate its converter circuit 314 as an inverter to provide power to the first load 20a. The master controller 330 can simultaneously command the second and third power routing units 310b, 310c to operate their converter circuits 314 as rectifiers to provide the power needed to support operation of the converter 314 of the first power routing unit 310a.

[0035] Figure 4 The arrangement shown in FIG. 3 can also be used to support flexible configuration of power delivery paths that provide different levels of power security for loads having different levels of criticality. For example, referring to FIG. 4, a UPS system 400 is shown that includes a first power routing unit 410a, a second power routing unit 410b, and a third power routing unit 410c. The first, second and third power routing units 410a, 410b, 410c are connected to respective loads 420a, 420b, 420c, whose AC input ports are collectively connected to the AC source 10 and whose DC ports are collectively coupled to the DC bus 320. Each of the first, second and third power routing units 410a, 410b, 410c contains a static switch 412, a converter circuit 414, and a control circuit 416 that controls the static switch 412 and the converter circuit 414. The master controller 430 is configured to communicate with the control circuits 416 to provide monitoring and management control. Figure 5, the second load 20b can have greater criticality than the first and third loads 20a, 20c, and the first and second power routing units 310a, 310b can be used to provide a dual conversion chain for providing improved power quality to the second load 20b. Specifically, the first power routing unit 310a can provide power to the first load 20a via its static switch 312, and can incidentally operate its converter circuit 314 as a rectifier to provide power to the DC bus 320. The second power routing unit 310b can open its static switch 312 and operate its converter circuit 314 as an inverter to provide power to the second load 20b from the DC bus 320, thereby isolating the second load 20b from quality deviations of the AC source 10. In this mode of operation, the static switch 312 of the second power routing unit 310b can be used in a manner similar to the use of a static bypass switch in a conventional dual conversion UPS. For example, in response to the power quality of the AC source 10 meeting certain power quality criteria, the static switch 312 of the second power routing unit 310b can be closed and the converter circuit 314 of the second power routing unit 310b can be disabled, so that power can be provided to the second load 20b in a more efficient manner. If the power quality of the AC source 10 deviates again, the static switch 312 can be opened and the second load 20b can again be powered with a dual conversion power train.

[0036] In other embodiments, the third power routing unit 310c can be used in a similar manner, so that both the first and third power routing units 310a, 310c provide power to the DC bus 320 for use by the converter circuit 314 of the second power routing unit 310b. The power safety allocation can also be dynamically adjusted. For example, as shown in Figure 6 , the system can be configured to transition to operating the converter circuits 314 of the second and third power routing units 310b, 310c to provide a dual conversion power train for the third load 20c. Such dynamic configurability can be particularly useful in some applications, such as data center applications in which the loads 20a, 20b, 20c are different groups of servers or other computing devices running processes with different power safety needs.

[0037] Figure 7 A control architecture that can be used to support power transfer between power routing units is shown according to other embodiments. Referring to Figure 7 and in conjunction with Figure 8 , the power routing units 310a, 310b, 310c can be configured to operate their converter circuits 314 to provide voltage or current control to the DC bus 320. As shown in Figure 8As shown in FIG. 3, the first and second power routing units 310a, 310b can be used to provide power to a third power routing unit 310c having a faulty static switch 312. To facilitate the transfer, the converter circuit 314 of the first power routing unit 310a can operate in a voltage control mode in which it maintains a desired voltage on the DC bus 320, while the converter circuit of the second power routing unit 310 operates in a controlled current mode in which it provides a desired amount of current to the DC bus 320. The amount of current provided by the second power routing unit 310b can be commanded by the master controller 330.

[0038] Each of the power routing units 310a, 310b, 310c can be configured to provide a control architecture for its converter 314 that supports multiple control modes. In the voltage control mode, a compensator 710 of the voltage loop provides a first current command I DC1 to a current loop having a compensator 730 via a selector 720, which provides a control signal to a pulse width modulation (PWM) drive circuit 740 that drives the transistors or other switching elements of the converter. However, when operating in the current control mode, the selector 720 instead provides a second current command I DC2 to the current loop, where the second current command I DC2 represents a desired current output of the converter. The second current command I DC2 may be provided, for example, by the master controller 330. The compensators 710, 730 can take any of a variety of different forms, including but not limited to, proportional-derivative, integral, proportional-integral-derivative (PID), lead-lag, and combinations thereof.

[0039] According to other embodiments, a power routing unit can include more than one static switch to support other UPS system configurations. For example, referring to FIG. 9, Figure 9 a system can include first and second power routing units 910a, 910b each including first and second static switches 912a, 912b and a converter circuit 914. AC output ports of the first and second power routing units 910a, 910b are coupled to respective first and second loads 20a, 20b. First and second AC inputs of the power routing units 910a, 910b are connected to respective ones of first and second AC sources 10a, 10b. DC ports of the first and second power routing units 910a, 910b are commonly coupled to a DC bus 920.

[0040] This arrangement can be used to provide flexibility in power routing and redundancy in the event of component or power supply failure. For example, this arrangement allows the loads 20a, 20b to be coupled to either of the AC sources 10a, 10b via the static switches 912a, 912b. This arrangement can also be used to provide dual conversion power chains for either of the loads 20a, 20b.

[0041] In the drawings and specification, there have been disclosed exemplary embodiments of the inventive subject matter. Although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the inventive subject matter being defined by the following claims.

Claims

1. An uninterruptible power supply system comprising: a plurality of power routing units each comprising: a first AC port; a second AC port; a static switch configured to couple and decouple the first AC port and the second AC port; a DC port; and a converter circuit coupled between the second AC port and the DC port, wherein the DC ports of the power routing units are collectively coupled to a DC bus; and a control circuit configured to detect a failure of the static switch of a first power routing unit, and configured to transfer power from a second power routing unit to a load connected to the second AC port of the first power routing unit through the DC bus and the converter circuit of the first power routing unit in response to the failure of the static switch of the first power routing unit.

2. The system of claim 1, wherein the first AC ports of the first power routing unit and the second power routing unit are connected to a same AC source.

3. The system of claim 2, wherein the load connected to the second AC port of the first power routing unit comprises a first load, and wherein the second AC port of the second power routing unit is connected to a second load.

4. The system of claim 1, wherein the control circuit is configured to detect the failure of the static switch of the first power routing unit, and configured to responsively transfer power from the second power routing unit and a third power routing unit to the load connected to the second AC port of the first power routing unit through the DC bus and the converter circuit of the first power routing unit.

5. The system of claim 1, wherein the control circuit comprises a respective control circuit associated with a respective one of the power routing units.

6. An uninterruptible power supply system comprising: a plurality of power routing units each comprising: a first AC port; a second AC port; a static switch configured to couple and decouple the first AC port and the second AC port; a DC port; and a converter circuit coupled between the second AC port and the DC port, wherein the DC ports of the power routing units are collectively coupled to a DC bus, and wherein a failure of the static switch of a first power routing unit of the plurality of power routing units can be detected, and the power routing units can be selectively combined to provide at least one double conversion uninterruptible power supply (UPS) in response to the failure of the static switch of the first power routing unit, wherein the at least one double conversion UPS comprises the converter circuit of the first power routing unit as a rectifier receiving AC power from the first AC port of the first power routing unit and the converter circuit of the second power routing unit as an inverter providing power to a load connected to the second AC port of the second routing unit.

7. A method of operating a system comprising a plurality of power routing units, each power routing unit comprising: a first AC port, a second AC port, a DC port, a static switch configured to couple the first AC port and the second AC port, and a converter circuit coupled between the second AC port and the DC port, the method comprising: coupling the DC port of the power routing unit collectively to a DC bus; detecting a failure of the static switch of the first power routing unit; and transmitting power from a second power routing unit to an AC load connected to the first power routing unit through the DC bus and the converter circuit of the first power routing unit in response to the failure of the static switch of the first power routing unit.

8. The method of claim 7, wherein the first AC port of the first power routing unit and the second power routing unit are connected to a same AC source.

9. The method of claim 8, wherein the load connected to the first power routing unit comprises a first load connected to a second AC port of the first power routing unit, and wherein the second AC port of the second power routing unit is connected to a second AC load.

10. The method of claim 7, further comprising: transmitting power from a third power routing unit to the load through the DC bus and the converter circuit of the first power routing unit in response to the detected failure.

10. The method of claim 9, wherein the third power routing unit is connected to the DC bus.

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