U.S. patent application number 12/623817 was filed with the patent office on 2010-04-29 for nested redundant uninterruptible power supply apparatus and methods.
This patent application is currently assigned to Eaton Corporation. Invention is credited to Frederick Tassitino, JR., John G. Tracy.
Application Number | 20100102636 12/623817 |
Document ID | / |
Family ID | 38179794 |
Filed Date | 2010-04-29 |
United States Patent
Application |
20100102636 |
Kind Code |
A1 |
Tracy; John G. ; et
al. |
April 29, 2010 |
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.
Inventors: |
Tracy; John G.;
(Hendersonville, NC) ; Tassitino, JR.; Frederick;
(Wake Forest, NC) |
Correspondence
Address: |
MYERS BIGEL SIBLEY & SAJOVEC
PO BOX 37428
RALEIGH
NC
27627
US
|
Assignee: |
Eaton Corporation
|
Family ID: |
38179794 |
Appl. No.: |
12/623817 |
Filed: |
November 23, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11561663 |
Nov 20, 2006 |
7638899 |
|
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12623817 |
|
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|
|
60781102 |
Mar 10, 2006 |
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Current U.S.
Class: |
307/80 |
Current CPC
Class: |
H02J 9/062 20130101;
H02M 2007/4822 20130101; H02J 3/38 20130101; H02M 7/493 20130101;
H02J 9/06 20130101 |
Class at
Publication: |
307/80 |
International
Class: |
H02J 3/38 20060101
H02J003/38 |
Claims
1. A UPS assembly, comprising: a frame; a plurality of UPS modules
mounted in and/or on the frame and configured to be coupled in
parallel to serve a load; an first digital communications bus
coupled to each of the UPS modules; and a control circuit mounted
in and/or on the frame, coupled to the first digital communications
bus and configured to determine a magnitude of the load and to
selectively enable or disable the UPS modules based on the
determined magnitude of the load to maintain service to the
load.
2. The system of claim 1, wherein the control circuit is configured
to selectively enable and disable the UPS modules to maintain
service to the load when the determined magnitude of the load meets
a predetermined criterion and to collectively disable the UPS
modules when the determined magnitude of the load fails to meet the
predetermined criterion.
Description
RELATED APPLICATIONS
[0001] The present application is a Continuation Application of
U.S. patent application Ser. No. 11/561,663, filed Nov. 20, 2006 in
the United States Patent Office which claims priority from U.S.
Provisional Application No. 60/781,102, filed Mar. 10, 2006, the
disclosures of which are hereby incorporated herein in their
entirety by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to uninterruptible power
supply (UPS) apparatus and methods and, more particularly, to
parallel redundant UPS apparatus and methods.
[0003] A variety of different techniques have been used to improve
reliability of uninterruptible power supply systems. The techniques
include standby redundant, serial redundant, and parallel redundant
approaches. A typical standby redundant UPS configuration includes
one or more UPS units operating on a stand-by basis, with no load
or only a partial load, which can immediately back up a faulty UPS
unit by a transfer of the load. A typical serial redundant
arrangement involves first and second UPSs connected in a serial
fashion wherein, in a first mode of operation, the first UPS is
bypassed while the second UPS is serving the load and, in a second
mode of operation, the second UPS is bypassed while the first UPS
serves the load, such that the first and second UPSs may serve as
standby backups for one another.
[0004] In a typical parallel redundant arrangement, multiple
uninterruptible power supplies (UPSs) are coupled in parallel to a
load to provide redundancy and, often, increased load capability.
Parallel redundant arrangements of AC power supplies (e.g., UPSs)
are described, for example, in U.S. Pat. No. 5,745,357 to
Tassitino, Jr. et al., U.S. Pat. No. 6,549,440 to Tassitino, Jr. et
al., U.S. Pat. No. 6,803,679 to Luo et al., U.S. Pat. No. 6,118,680
to Wallace et al., U.S. Pat. No. 4,104,539 to Hase, United States
Patent Publication No. 2005/0162792 to Wang et al., and United
States Patent Publication No. 2005/0073783 to Luo et al.
SUMMARY OF THE INVENTION
[0005] In some embodiments of the present invention, 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.
[0006] In some embodiments, 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.
The control circuitry may be 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.
[0007] In further embodiments of the present invention, respective
ones of the redundant groups of UPSs include respective UPS
assemblies. Each UPS assembly includes 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 to
communicate with a control circuit of another UPS assembly over a
second digital communications bus. The control circuit may include
a network bridge between the first and second digital
communications busses. Each UPS assembly may further include a
bypass circuit, and the control circuit in the UPS assembly may be
configured to control the bypass circuit to bypass the UPS modules
in the UPS assembly. The UPS modules and control circuit of a UPS
assembly may be mounted in and/or on a common frame.
[0008] Further embodiments of the present invention provide a UPS
assembly including a frame, a plurality of UPS modules mounted in
and/or on the frame, a first digital communications bus coupled to
each of the UPS modules, and a 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 is 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. The AC waveform synchronization
information may include frequency and phase error information. The
control circuit may be 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.
[0009] In some embodiments, the control circuit may be configured
to provide the at least two redundant subgroups when a loading of
the UPS assembly is less than predetermined level. The control
circuit may be 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. The UPS assembly may
further include a bypass circuit mounted in and/or on the frame,
and the control circuit may be configured to control the bypass
circuit to bypass the plurality of UPS modules. The control circuit
may include a network bridge between the first and second digital
communications busses.
[0010] Additional embodiments of the present invention provide
methods of operating an uninterruptible power supply (UPS) system.
At least three UPSs are connected in parallel to a common load. The
at least three UPSs are controlled to support at least two
redundant groups among the UPSs and to further support at least two
redundant subgroups among at least one of the redundant groups of
UPSs. Controlling the at least three UPSs to support at least two
redundant groups among the UPSs and to further support at least two
redundant subgroups among at least one of the redundant groups of
UPSs may include providing the at least two redundant subgroups
when a loading of the at least one redundant group is less than a
predetermined level. For example, selective enabling and disabling
of the UPSs within the at least one redundant group may be allowed
when the loading of the at least one redundant group is less than
the predetermined level and collective enabling and disabling of
the UPSs in the at least one redundant group may be required when
the loading of the at least one redundant group is greater than the
predetermined level. Respective ones of the redundant groups of
UPSs may include respective UPS assemblies, each UPS assembly
including 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 illustrates a nested redundant UPS system and
operations thereof according to some embodiments of the present
invention.
[0012] FIG. 2 illustrates a nested redundant UPS system using
modular UPS assemblies and operations thereof according to further
embodiments of the present invention.
[0013] 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.
[0014] FIGS. 5 and 6 illustrate communications operations of a
modular UPS assembly according to some embodiments of the present
invention.
[0015] FIGS. 7 and 8 illustrate exemplary UPS module
synchronization control architectures according to further
embodiments of the present invention.
[0016] FIG. 9 is a flowchart illustrating operations for nested
redundant operation of a UPS system according to further
embodiments of the present invention.
DETAILED DESCRIPTION
[0017] Specific exemplary embodiments of the invention now will be
described with reference to the accompanying drawings. This
invention may, however, be embodied in many 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 invention to those skilled in the art. The terminology
used in the detailed description of the particular exemplary
embodiments illustrated in the accompanying drawings is not
intended to be limiting of the invention. In the drawings, like
numbers refer to like elements.
[0018] As used herein, the singular forms "a", "an" and "the" are
intended to include the plural forms as well, unless expressly
stated otherwise. It will be further understood that the terms
"includes," "includes," "including" and/or "including," 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. It will be understood that when an element is
referred to as being "connected" or "coupled" to another element,
it can be directly connected or coupled to the other element or
intervening elements may be present. Furthermore, "connected" or
"coupled" as used herein may include wirelessly connected or
coupled. As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items.
[0019] 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
invention 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 relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
[0020] Some embodiments of the present invention arise from a
realization that improved reliability in UPS systems may be
achieved by using a nested redundant arrangement of UPSs. In some
embodiments, a plurality of parallel-connected UPSs is controlled
such that at least two redundant groups of the UPSs are provided
and, within, at least one of these redundant groups, at least two
redundant subgroups of the UPSs are provided. Such an approach may
be particularly advantageous in modular UPS configurations. A
nested redundant structure may be implemented, for example, using
modular UPS assemblies that include respective pluralities of UPS
modules and respective control circuits that control the UPS
modules and communicate with one another to support nested
redundancy.
[0021] FIG. 1 illustrates a UPS system 100 according to some
embodiments of the present invention. The system 100 includes a
plurality of UPSs 112a, 112b, 112c, 112d connected in parallel to a
load 20. As shown, the UPSs 112a, 112b, 112c, 112d are "on-line"
UPSs, but it will be understood that, in some embodiments of the
present invention, "standby," "line interactive" or other
configurations may be used. The UPSs 112a, 112b, 112c, 112d are
controlled to provide first and second redundant groups 110a, 110b,
e.g., the second group 110b may serve as a backup to the first
group 110a (and/or vice versa) such that one of the groups 110a,
110b may continue to serve the load 20 in the event of failure of
the other of the groups 110a, 110b. It will be appreciated that
this redundant operation may be limited to a certain operational
envelope, e.g., the redundancy may be limited to cases in which the
load 20 is less than a capacity of an individual one of the UPS
groups 110a, 110b, and that, when such capacity is exceeded, the
UPS groups 110a, 110b may, for example, be collectively disabled
and/or bypassed.
[0022] Within at least one group 110a there are further defined
redundant subgroups 111a, 111b, the first subgroup 111a including
two UPSs 112a, 112b and the second subgroup 111b including two UPSs
112c, 112d. Within the group 110a, for example, the first subgroup
111a may serve to backup operation of the second subgroup 111b
and/or vice versa.
[0023] It will be understood that the groups 110a, 110b and
subgroups 111a, 111b are provided for purposes of illustration, and
that other redundant groupings and subgroupings may be used in
other embodiments of the present invention. For example, in some
embodiments, redundant subgroups may be provided in all redundant
groups or only in a subset of the redundant groups. In some
embodiments, additional redundant groups may be provided to backup
the groups 110a, 110b, and these may or may not include redundant
subgroups therein. According to further embodiments, an even higher
level of nested redundancy may be provided, e.g., some or all of
the UPSs 112a, 112b, 112c, 112d may actually include multiple
parallel-connected UPSs that are arranged to provide redundant
subgroups therein. Other redundancy may also be provided, e.g.,
some or all of the UPSs 112a, 112b, 112c, 112d may include
redundant components, such as redundant rectifiers or inverters. In
still further embodiments, redundant groups and/or subgroups may be
dynamically redefined depending, for example, on loading and/or
disposition (e.g., availability due to maintenance or other events)
of particular UPSs.
[0024] FIG. 2 illustrates a UPS system 200 with a modular
architecture according to further embodiments of the present
invention. First and second redundant groups of UPSs are provided
in the form of respective UPS assemblies 210a, 210b. The UPS
assemblies 210a, 210b include respective pluralities of UPS modules
214 that are connected in parallel to a load 20 and that
communicate with respective control circuits 212. The control
circuits 212 are also configured to communicate with one another.
According to embodiments of the present invention, the control
circuits 212 and the UPS modules 214 support redundant operation of
the UPS assemblies 210a, 210b such that the pluralities of UPS
modules 214 therein serve as respective redundant groups of UPSs,
e.g., the group of UPS modules 214 of the UPS assembly 210b may act
as a group to back up the group of UPS modules 214 of the UPS
assembly 210a. Within one or both of the UPS assemblies 210a,
2101), an inner redundancy is provided among the UPS modules 214
thereof. For example, as shown, the modules 214 and control circuit
212 within a UPS assembly may be configured to provide redundant
subgroups 211a, 211b within the UPS assembly.
[0025] Such nested redundancy may be achieved using communications
among the control circuits 212 and the UPS modules 214. For
example, in some embodiments, each UPS module 214 within the first
UPS assembly 210a may communicate status information to the
associated control circuit 212. Such status information may
indicate, for example, whether a failure is imminent in the UPS
module 214 and information pertaining the load currently being
served by the UPS module 214. In response to such information, the
control circuit 212 may determine whether a selective disabling of
the UPS module 214 may be allowed such that other UPS modules 214
within the UPS assembly 210a may continue to serve the load 20. For
example, as explained in detail with reference to FIG. 7 below, if
loading of the UPS assembly 210a is below a certain threshold, it
may be possible to let other UPS modules 214 in the UPS assembly
210a to continue to supply power to the load 20. If, however, the
loading on the UPS assembly 210a is so high that the remaining
operational UPS modules 214 do not have sufficient capacity to
serve the load 20, the control law of the control circuit 212 may
require collective disabling of all of the UPS modules 214 in the
UPS assembly 210a.
[0026] The control circuit 210 may further communicate this
information to other UPS assemblies, so that they may take
coordinated action. For example, in response to receipt of such
information from the first UPS assembly 210a, if the control
circuit 212 of the second UPS assembly 210b determines that it will
not be able to serve the load 20 once the first UPS assembly 210a
goes completely off-line, the control law of the control circuit
212 of the second UPS assembly 210b may require collective
disabling of all of its currently operational UPS modules 214 as
well. This election may be further communicated to the control
circuit 212 of the first UPS assembly 212 and/or to other UPS
assemblies (not shown) that may be connected to the load 20, so
that they may take further actions. For example, if a sufficient
number of UPS assemblies are not capable of serving the load 20,
they may be collectively bypassed, such that an AC utility or other
power source is directly connected to the load 20.
[0027] FIG. 3 illustrates exemplary configurations for a UPS
assembly 300 according to some embodiments of the present invention
that may be used in a UPS system along the lines described above
with reference to FIG. 2. UPS modules 310 include a rectifier 312
configured to receive an AC input via a first switch (e.g., a
contactor or relay) 316. An inverter 313 is coupled by a DC bus 315
to the rectifier 312. An output of the inverter 313 may be
connected and disconnected from a load (not shown in FIG. 3) via a
second switch 317. A DC-DC converter 314 is also coupled to the DC
bus 315 and is configured to be connected to a battery (not shown).
The DC-DC converter 314 may allow the battery to provide DC power
to the DC bus 315 in the absence of AC power at the input of the
rectifier 312. The DC-DC converter 314 may also allow charging of
the battery from the DC bus 315. A control circuit 311 is
configured to control the rectifier 312, inverter 313, DC-DC
converter 314 and the switches 316, 316. The control circuit 311
includes a digital communications interface, here shown as a
controller area network (CAN) interface 311a, coupled to a digital
communications bus 330.
[0028] The CAN bus 330 is also coupled to a CAN interface 322a of a
control circuit 322 of an I/O and bypass module 320 of the UPS
assembly 300. The I/O and bypass module 320 further includes a
bypass switch 326 that is configured to bypass the UPS modules 310
responsive to a control signal from the control circuit 322. The
I/O and bypass module 320 further includes a CAN bridge 324 that
provides communications between the internal communications bus 330
and an external bus 340. Via the CAN bridge 324 and the external
bus 340, information may be exchanged with other UPS
assemblies.
[0029] FIG. 4 illustrates an exemplary implementation of a modular
UPS assembly 300' having an architecture along the lines of the UPS
assembly 300 illustrated in FIG. 3. In the illustrated embodiments,
three UPS modules 310' and an I/O and bypass module 320' are
mounted in and/or on a common frame, here shown as a cabinet 410.
It will be understood that the configuration illustrated in FIG. 4
may be appropriate, for example, to a relatively high capacity UPS
system, and that other form factors, including greater or lesser
numbers of UPS modules, may be used in other embodiments of the
present invention.
[0030] FIGS. 5 and 6 illustrate exemplary signaling that may be
used in the modular UPS assembly 300 of FIG. 3. The control circuit
322 of the I/O and bypass module 320 may transmit waveform
synchronization information and enable/disable commands to the UPS
modules 310 over the internal CAN bus 330. This information may
also be transmitted to another UPS assembly external to the UPS
assembly 300 via the CAN bridge 324. Referring to FIG. 6, the UPS
modules 310 may transmit waveform synchronization information and
status information to the control circuit 322 over the internal CAN
bus 330. In other embodiments of the present invention,
synchronization may be achieved without such explicit signaling,
for example, by using techniques along lined described in U.S. Pat.
No. 5,745,355 to Tracy et al. and U.S. Pat. No. 5,745,356 to
Tassitino, Jr. et al, the contents of each of which is incorporated
by reference herein in their entireties.
[0031] According to some embodiments of the present invention, the
waveform synchronization information may include frequency and
phase error information that may be used by the modules 310 to
synchronize operation of their inverters 313. For example,
referring to FIG. 7, synchronization information transmitted to a
control circuit of a UPS module, such as the UPS modules 310 of
FIG. 3, may include a target frequency and phase error that are
passed to a phase locked loop controller 710 that generates a
reference signal for an inverter driver 730 of the module. As
shown, for purposes of balancing load share among modules, the
phase lock loop compensation may be augmented by a load share
controller 720 that operates responsive to a measure of power
output of the module, along lines, for example, described in U.S.
Pat. No. 6,549,440 to Tassitino et al., the disclosure of which is
hereby incorporated by reference herein in its entirety. As shown
in FIG. 8, in some embodiments, the phase locked loop and load
share control functions shown in FIG. 7 may be implemented in an AC
waveform reference generator 810 that generates an AC waveform
reference signal for an inverter driver 820.
[0032] FIG. 9 illustrates exemplary UPS operations for nested
redundant operation of a UPS assembly according to further
embodiments of the present invention. A load is powered by at least
two parallel UPS assemblies, e.g., modular UPS assemblies such as
the assemblies 300, 300' of FIGS. 3 and 4 (block 910). Upon
detection of a failure of a UPS module in a first one of the UPS
assemblies (block 920), the control circuit of the first UPS
assembly determines whether the level of loading allows for
intra-assembly redundancy, i.e., will allow remaining operative UPS
modules in the assembly to continue supplying the load (block 930).
If the load is sufficiently low, the control circuit may disable
the failed module, and allow the remaining modules to continue to
drive the load (block 940), thus providing intra-assembly
redundancy. It will be understood that a second module mail fail in
a second one of the UPS assemblies, which may lead to disabling of
that second module without requiring changes to the operation of
the first UPS assembly. If insufficient capacity exists, however,
the control circuit collectively disables all of the modules in the
assembly and signals another assembly to inform it of the
collective shutdown (block 950). In further embodiments of the
present invention, other operations may be performed. For example,
in some embodiments, dynamic redefinition of redundant groups
and/or subgroups may occur in response to shutdown or other
unavailability of particular modules.
[0033] In the drawings and specification, there have been disclosed
exemplary embodiments of the invention. 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 invention being
defined by the following claims.
* * * * *