Uninterruptible power supply system and method using interconnected power routing units

Abstract

The invention provides an uninterruptible power supply system and method utilizing interconnected power routing units. 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 commonly 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 with the filing date of April 20, 2017, application number 201780034218.0, and invention title "Uninterruptible Power Supply System and Method Using Interconnected Power Routing Units". Technical Field

[0002] The subject matter of the present invention relates to power distribution systems and methods, and more particularly, to uninterruptible power supply (UPS) systems and methods. Background Art

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

[0004] UPS systems can be implemented using modular components. For example, a UPS system can include a plurality of UPS modules, each of which can include, for example, a rectifier, an inverter, and a DC / DC converter for interfacing to a battery. The UPS modules can be installed in a common rack along with control and interface circuitry such as a bypass switch. The UPS modules can be designed to operate in parallel to provide scalable power capacity, e.g., the modules can 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 the Eaton ® Power XPert 9395 UPS (described at http: / / powerquality.eaton.com), which can be configured to include two or more uninterruptible power modules (UPMs), each UPM including 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, filed July 8, 2013, titled "UPS Systems and Methods Using Variable Configuration Modules" (Attorney Docket No.: 9060-321), and are incorporated herein by reference. Summary of the Invention

[0005] Some embodiments of the subject matter of the present invention provide a system that 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 commonly 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 a first power routing unit may be coupled to a first AC power source, and the first AC port of a second power routing unit may be coupled to a second AC power source. The control circuit may be configured to, 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, cause the second power routing unit to provide power to the first power routing unit via the DC bus.

[0007] In other embodiments, the second AC port of a first power routing unit may be coupled to a first load, and the second AC port of a second power routing unit may be coupled to a second load. The second power routing unit may be configured to provide power to the first load from a second AC power source via the static switch and 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 may be configured to control the power routing units to provide power to a first power routing unit from a second power routing unit and a third power routing unit via the DC bus. The control circuit may be configured to operate the second power routing unit to regulate the voltage on the DC bus, and 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 may be commonly coupled to an AC power source, and the first AC ports of the first, second, and third power routing units may be coupled to corresponding first, second, and third loads.

[0009] According to other embodiments, the first AC ports of the first and second power routing units may be commonly coupled to an AC power source, the second AC ports of the first and second power routing units may be coupled to respective first and second loads, and the control circuit may be configured to simultaneously supply 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 circuits of the first and second power routing units. The control circuit may be configured to operate two 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 may 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 may include respective local control circuits located in the power routing units, and the respective local control circuits are configured to operate the associated converter circuits to selectively provide a first mode and a second mode, in the first mode the converter circuit regulates the voltage on the DC bus, and in the second mode the converter circuit supplies a regulated current to the DC bus.

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

[0013] In other embodiments, the static switch may be a first static switch, and each of the power routing units may 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 and a second mode, in the first mode the converter regulates the voltage on the external DC bus, and in the second mode the converter supplies a regulated current to the external DC bus.

[0015] Other embodiments provide methods that include 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 bi-directional converter circuit coupled between the second AC port and the DC port. The method further includes commonly 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 THE DRAWINGS

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

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

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

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

[0020] Figure 5 and Figure 6 FIG. 5 is a schematic diagram showing a UPS system having a reconfigurable operation mode utilizing a power routing unit according to some embodiments.

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

[0022] Figure 8 FIG. 7 is a schematic diagram showing Figure 7 the application of the control architecture of FIG. 6 in a UPS system.

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

[0024] Specific exemplary embodiments of the subject matter of the present invention will now be described with reference to the accompanying drawings. However, the subject matter of the present invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. 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 invention to those skilled in the art. In the drawings, like reference numerals refer to like items. It should be understood that when an 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 may 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 limit the subject matter of the present invention. 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 should also be understood that when used in the specification, the terms "includes", "comprises", "including" and / or "comprising" specify the presence of the stated features, integers, steps, operations, items, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, items, 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 the subject matter of the present invention belongs. It should also be 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 the relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0027] Figure 1 A system is shown in accordance with some embodiments of the subject matter of the present invention. The system includes a plurality of power routing units 110 that are collectively connected to an external DC bus 120. Each of the power routing units 110 includes at least one static switch 112 that 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 that is coupled between the AC output port 113 and a DC port 115 that is coupled to the DC bus 120. The converter circuit 114 is configured to support power flow in two directions to support a variety of different settings of the power routing unit 110, as will be explained in more detail with reference to Figures 3 to 9 explained in more detail.

[0028] It should be understood that the power routing unit 110 can be implemented using any of a large number of different types of circuits. For example, the static switch 112 can be implemented using any of a variety 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 variety 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 variety 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 according to other embodiments is shown. The power routing unit 210 includes a three-phase static switch 212, which is implemented using antiparallel-connected silicon controlled rectifier (SCR) pairs. The static switch 212 is coupled between the AC input port 211 and the AC output port 213 of the power routing unit. The power routing unit 210 further includes a three-phase bridge circuit 214, which includes transistors Q (e.g., IGBTs or power MOSFETs) coupled to corresponding half-bridge pairs for corresponding phases and corresponding inductors L for corresponding phases. The bridge circuit 214 is coupled between the AC output port 213 and the 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 the maintenance of the voltage on the DC bus connected to the DC port 215, but it should be understood that such capacitance can be provided or supplemented by capacitors located outside the power routing unit 210. The control circuit 216 is configured to control the static switch 212 and the bridge circuit 214 to provide various operating modes that support 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 variety of different analog and / or digital circuits, including, for example, a control circuit employing a data processing circuit, such as a microcontroller or a microprocessor.

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

[0031] Figure 3 The arrangement shown in can be implemented as a static UPS system without a battery. Specifically, under normal operating conditions, power can be provided from the corresponding source among the first and second AC sources 10a, 10b to the first and second loads 20a, 20b via the static switches of the corresponding units among the first and second power routing units 310a, 310b. In response to a fault of, for example, the first AC source 10a, power can be provided from the second power source 20b to the first load 20a 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. Similarly, in response to a fault of the second AC source 10b, power can be provided from the first AC source 10a to the second load 20b 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.

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

[0033] Figure 4Another UPS system arrangement is shown, which advantageously uses the power routing unit described above. The AC outputs of the first, second, and third power routing units 310a, 310b, 310c are connected to corresponding loads 20a, 20b, 20c, their AC input ports are commonly connected to the AC source 10, and their DC ports are commonly coupled to the DC bus 320. Each of the first, second, and third power routing units 310a, 310b, 310c includes 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 main controller 30 is configured to communicate with the control circuit 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 supply power to their corresponding loads 20a, 20b, 20c via their static switches 312. In response to a fault of, for example, the static switch 312 of the first power routing unit 310a, the second and third power routing units 310b, 310c can supply power to the first load 20a via the DC bus 320. Such operation can be controlled by the main controller 330. For example, the main controller 330 can receive status information indicating a fault of its static switch 312 from the first power routing unit 310a, and can command the first power routing unit 310a to operate its converter circuit 314 as an inverter to supply power to the first load 20a. The main 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 required to support the operation of the converter 314 of the first power routing unit 310a.

[0035] Figure 4 The arrangement shown in can also be used to support flexible configuration of the power delivery path, which provides different levels of power security for loads with different levels of criticality. For example, referring to Figure 5, the second load 20b may have a greater criticality than the first and third loads 20a, 20c, and the first and second power routing units 310a, 310b may 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 may supply power to the first load 20a via its static switch 312 and may incidentally operate its converter circuit 314 as a rectifier to supply power to the DC bus 320. The second power routing unit 310b may open its static switch 312 and operate its converter circuit 314 as an inverter to supply power from the DC bus 320 to the second load 20b, thereby isolating the second load 20b from the quality deviations of the AC source 10. In this functional mode, the static switch 312 of the second power routing unit 310b may be used in a manner similar to that of a static bypass switch used in a conventional dual conversion UPS. For example, in response to the power quality of the AC source 10 meeting a specific power quality standard, the static switch 312 of the second power routing unit 310b may be closed and the converter circuit 314 of the second power routing unit 310b may be disabled, such that power may be supplied 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 may be opened and the second load 20b may be powered again using the dual conversion power system.

[0036] In other embodiments, the third power routing unit 310c may be used in a similar manner such that both the first and third power routing units 310a, 310c supply power to the DC bus 320 for use by the converter circuit 314 of the second power routing unit 310b. The power safety distribution may also be adjusted dynamically. For example, as Figure 6 shown, the system may 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 system for the third load 20c. In some applications, such dynamic configurability may be particularly useful, such as in data center applications where the loads 20a, 20b, 20c are different groups of servers or other computing devices that run processes with different power safety requirements.

[0037] Figure 7 illustrates a control architecture according to other embodiments that may be used to support power transfer between power routing units. Referring to Figure 7 and in conjunction with Figure 8 , the power routing units 310a, 310b, 310c may be configured to operate their converter circuits 314 to provide voltage or current control of the DC bus 320. As Figure 8As shown, the first and second power routing units 310a, 310b can be used to supply power to a third power routing unit 310c having a faulty static switch 312. To facilitate such transfer, the converter circuit 314 of the first power routing unit 310a can operate in a voltage control mode, where 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, where it supplies 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 main controller 330.

[0038] Each of the power routing units 310a, 310b, 310c can be configured to provide a control architecture that supports multiple control modes for its converter 314. In the voltage control mode, a compensator 710 of the voltage loop provides a first current command I to a current loop having a compensator 730 via a selector 720 DC1 , and the compensator 730 provides a control signal to a pulse width modulation (PWM) drive circuit 740, which drives the transistors or other switching elements of the converter. However, when operating in the current control mode, instead, the selector 720 provides a second current command I to the current loop DC2 , where the second current command I DC2 represents the desired current output of the converter. The second current command I DC2 can be provided, for example, by the main control 330. The compensators 710, 730 can take any of a variety of different forms, including but not limited to, proportional differentiators, integrators, proportional integral-differentiators (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 Figure 9 , the 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. The AC output ports of the first and second power routing units 910a, 910b are coupled to corresponding first and second loads 20a, 20b. The first and second AC inputs of the power routing units 910a, 910b are connected to a corresponding one of first and second AC sources 10a, 10b. The 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 terms of power routing and redundancy in the event of a component or power supply failure. For example, this arrangement allows 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 a dual-conversion power chain for either of the loads 20a, 20b.

[0041] In the drawings and the specification, exemplary embodiments of the subject matter of the present invention have been disclosed. Although specific terms have been employed, they are used only in a general and descriptive sense and not for purposes of limitation, and the scope of the subject matter of the present invention is defined by the appended claims.

Claims

1. A 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 commonly coupled to a DC bus; and a control circuit configured to detect a fault in the static switch of a first power routing unit and configured to responsively transfer power from a second power routing unit to a load connected to the second AC port of the first power routing unit via the DC bus and the converter circuit of the first power routing unit.

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

3. The system according to 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 according to claim 1, wherein the control circuit is configured to detect the fault in 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 via the DC bus and the converter circuit of the first power routing unit.

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

6. A 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 commonly coupled to a DC bus, and wherein the power routing units can be selectively combined to provide at least one double-conversion uninterruptible power supply (UPS).

7. The system according to claim 6, wherein the at least one double-conversion UPS comprises the converter circuit of a first power routing unit that receives AC power as a rectifier from the first AC port of the first power routing unit and the converter circuit of a second power routing unit that provides power as an inverter to a load connected to the second AC port of the second routing unit.

8. The system according to claim 6, wherein the first and second power routing units can be configured to operate as a double-conversion UPS in a first configuration and to independently serve respective first and second loads in a second configuration.

9. The system according to claim 6, wherein the power routing units can be configured to independently serve respective loads.

10. A method of operating a system including 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 ports of the power routing units together to a DC bus; detecting a fault in the static switch of a first power routing unit; and responsive thereto, transmitting power from a second power routing unit to an AC load connected to the first power routing unit via the DC bus and the converter circuit of the first power routing unit.

11. The method according to claim 10, wherein the first AC ports of the first power routing unit and the second power routing unit are connected to the same AC source.

12. The method according to claim 11, wherein the load connected to the first power routing unit includes a first load connected to the 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.

13. The method according to claim 10, further comprising: responsive to the detected fault, transmitting power from a third power routing unit to the load via the DC bus and the converter circuit of the first power routing unit.

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