Nested Redundant Uninterruptible Power Supply Apparatus and Methods

Abstract

An uninterruptible power supply (UPS) system includes at least three UPSs configured to be connected in parallel to a common load. The system further includes control circuitry configured to support at least two redundant groups among the UPSs and to support at least two redundant subgroups among at least one of the redundant groups of UPSs. In this manner, a nested redundancy may be provided.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a nested redundant UPS system and operations thereof according to some embodiments of the present invention.

FIG. 2 illustrates a nested redundant UPS system using modular UPS assemblies and operations thereof according to further embodiments of the present invention.

FIGS. 3 and 4 illustrate a modular UPS assembly that may be used in a nested redundant UPS system according to additional embodiments of the present invention.

FIGS. 5 and 6 illustrate communications operations of a modular UPS assembly according to some embodiments of the present invention.

FIGS. 7 and 8 illustrate exemplary UPS module synchronization control architectures according to further embodiments of the present invention.

FIG. 9 is a flowchart illustrating operations for nested redundant operation of a UPS system according to further embodiments of the present invention.

Claims

1. An uninterruptible power supply (UPS) system, comprising: at least three UPSs configured to be connected in parallel to a common load: andcontrol circuitry configured to support at least two redundant groups among the UPSs and to support at least two redundant subgroups among at least one of the redundant groups of UPSs.

2. The system of claim 1, wherein the control circuitry is configured to provide the at least two redundant subgroups when a loading of the at least one redundant group is less than a predetermined level.

3. The system of claim 2, wherein the control circuitry is configured to allow selective enabling and disabling of the UPSs within the redundant group when the loading of the redundant group is less than the predetermined level and to require collective enabling and disabling of the UPSs in the redundant group when the loading of the redundant group is greater than the predetermined level.

4. The system of claim 1, wherein respective ones of the redundant groups of UPSs comprise respective UPS assemblies, each UPS assembly comprising a plurality of UPS modules and a control circuit configured to communicate with the plurality of UPS modules over a first digital communications bus and with a control circuit of another UPS assembly over a second digital communications bus.

5. The system of claim 4, wherein the control circuit comprises a network bridge between the first and second digital communications busses.

6. The system of claim 4, wherein each UPS assembly further comprises a bypass circuit, and wherein the control circuit in the UPS assembly is configured to control the bypass circuit to bypass the UPS modules in the UPS assembly.

7. The system of claim 4, wherein the plurality of UPS modules and control circuit of a UPS assembly are mounted in and/or on a common frame.

8. The system of claim 7, wherein the UPS assembly further comprises a bypass circuit mounted in and/or on the common frame, and wherein the control circuit is configured to control the bypass circuit to bypass the UPS modules.

9. A UPS assembly, comprising: a frame;a plurality of UPS modules mounted in and/or on the frame;an first digital communications bus coupled to each of the UPS modules; anda control circuit mounted in and/or on the frame, coupled to the first digital communications bus and configured to be coupled to a second digital communications bus, the control circuit operative to communicate AC waveform synchronization information to the UPS modules over the first digital communications bus and to another UPS assembly over the second digital communications bus.

10. The UPS assembly of claim 9, wherein the AC waveform synchronization information comprises frequency and phase error information.

11. The UPS assembly of claim 1, wherein the control circuit is configured, when the UPS assembly is connected in parallel to a load with the other UPS assembly, to operate the UPS assembly as a redundant backup for the other UPS assembly and to provide at least two redundant subgroups within its plurality of UPS modules.

12. The UPS assembly of claim 11, wherein the control circuit provides the at least two redundant subgroups when a loading of the UPS assembly is less than predetermined level.

13. The UPS system of claim 12, wherein the control circuit is configured to allow selective enabling and disabling of the UPS modules when the loading of the UPS assembly is less than the predetermined level and to require collective enabling and disabling of the UPS modules when the loading of the UPS assembly is greater than the predetermined level.

14. The UPS assembly of claim 9, further comprising a bypass circuit mounted in and/or on the frame and wherein the control circuit is configured to control the bypass circuit to bypass the plurality of UPS modules.

15. The UPS assembly of claim 9, wherein the control circuit comprises a network bridge between the first and second digital communications busses.

16. The UPS assembly of claim 9, wherein the first digital communications bus comprises a controller area network (CAN) bus.

17. A method of operating an uninterruptible power supply (UPS) system, comprising: connecting at least three UPSs in parallel to a common load: andcontrolling the at least three UPSs to support at least two redundant groups among the UPSs and to support at least two redundant subgroups among at least one of the redundant groups of UPSs.

18. The method of claim 17, wherein controlling the at least three UPSs to support at least two redundant groups among the UPSs and to support at least two redundant subgroups among at least one of the redundant groups of UPSs comprises providing the at least two redundant subgroups when a loading of the at least one redundant group is less than a predetermined level.

19. The method of claim 18, wherein providing the at least two redundant subgroups when a loading of the at least one redundant group is less than a predetermined level comprises allowing selective enabling and disabling of the UPSs within the at least one redundant group when the loading of the at least one redundant group is less than the predetermined level and requiring collective enabling and disabling of the UPSs in the at least one redundant group when the loading of the at least one redundant group is greater than the predetermined level.

20. The method of claim 17, wherein respective ones of the redundant groups of UPSs comprise respective UPS assemblies, each UPS assembly comprising a plurality of UPS modules and a control circuit configured to communicate with the UPS modules of the UPS assembly and with a control circuit of another UPS assembly.

21. The method of claim 18, wherein the UPS modules and control circuit of a UPS assembly are mounted in and/or on a common frame.