U.S. patent application number 16/180709 was filed with the patent office on 2019-05-16 for control of parallel battery utilization.
The applicant listed for this patent is Inventus Holdings, LLC. Invention is credited to Ryan MCMORROW, Matthew T. SMITH, Rachana VIDHI.
Application Number | 20190148956 16/180709 |
Document ID | / |
Family ID | 60203407 |
Filed Date | 2019-05-16 |
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United States Patent
Application |
20190148956 |
Kind Code |
A1 |
MCMORROW; Ryan ; et
al. |
May 16, 2019 |
CONTROL OF PARALLEL BATTERY UTILIZATION
Abstract
Systems and methods for allocating electrical current among
battery sets connected in a substantially parallel configuration. A
respective state of health is determined for each respective
battery set in a plurality of battery sets. The respective state of
health reflects a respective present amount of total energy able to
be stored by each respective battery set relative to a
specification of the respective battery set. A respective
allocation of electrical current for each battery set in the
plurality of battery sets is determined based on the respective
state of health for each respective battery set. A current flow
through each respective battery set is configured to its respective
allocation of electrical current based on determining the
respective allocation.
Inventors: |
MCMORROW; Ryan; (Jupiter,
FL) ; SMITH; Matthew T.; (North Palm Beach, FL)
; VIDHI; Rachana; (Palm Beach Gardens, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Inventus Holdings, LLC |
June Beach |
FL |
US |
|
|
Family ID: |
60203407 |
Appl. No.: |
16/180709 |
Filed: |
May 3, 2017 |
PCT Filed: |
May 3, 2017 |
PCT NO: |
PCT/US17/30887 |
371 Date: |
November 5, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15147654 |
May 5, 2016 |
9948119 |
|
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16180709 |
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Current U.S.
Class: |
307/9.1 |
Current CPC
Class: |
H02J 7/0063 20130101;
H02J 2007/0067 20130101; H02J 7/0013 20130101; H02J 3/32 20130101;
H02J 7/0069 20200101; B60L 58/21 20190201; H02J 7/0021 20130101;
H02J 7/0025 20200101; H02J 7/0024 20130101 |
International
Class: |
H02J 7/00 20060101
H02J007/00; H02J 3/32 20060101 H02J003/32 |
Claims
1. A method for allocating electrical current among battery sets
connected in a substantially parallel configuration, the method
comprising: receiving a respective state of health for each
respective battery set in a plurality of battery sets, the
respective state of health reflecting a respective present amount
of total energy able to be stored by each respective battery set
relative to a specification of the respective battery set;
determining, based on the respective state of health for each
respective battery set, a respective allocation of electrical
current for each battery set in the plurality of battery sets; and
configuring, based on determining the respective allocation, an
electrical current flow through each respective battery set to its
respective allocation of electrical current.
2. The method of claim 1, further comprising exchanging the
electrical current with an electrical power grid, and wherein the
plurality of battery sets comprise at least one repurposed battery,
each at least one repurposed battery having been used in an
application different from exchanging electrical current with an
electrical power grid.
3. The method of claim 2, wherein the plurality of battery sets is
part of a battery combination, the battery combination comprising
at least: a first battery set having a first state of health when
the battery combination is assembled; and a second battery having a
second state of health when the battery combination is assembled,
the second state of health being different than the first state of
health.
4. The method of claim 2, wherein the application comprises
providing electrical energy for an electrically powered
vehicle.
5. The method of claim 1, wherein determining the respective state
of health for each respective battery set is based upon a
combination of a number of charging and discharging cycles of each
respective battery set and an age of each respective battery
set.
6. The method of claim 1, further comprising receiving a
specification of least one of: a total amount of electrical current
to receive from an external power system for charging the plurality
of battery sets, or a total amount of electrical current to provide
to the external power system, and wherein the respective allocation
of electrical current for each battery set is a respective
percentage of the total amount of electrical current.
7. The method of claim 1, further comprising: coupling the
plurality of battery sets to an external power grid through an
inverter; and exchanging, based on the respective allocation,
electrical power between the external power grid and each battery
set in the plurality of battery sets .
8. An apparatus for controlling electrical current allocated to a
plurality of battery sets, the apparatus comprising: a current
division controller that, when operating: receives a respective
state of health for each respective battery set in a plurality of
battery sets, the respective state of health reflecting a
respective present amount of total energy able to be stored by each
respective battery set relative to a specification of the
respective battery set; determines, based on the respective state
of health for each respective battery set, a respective allocation
of electrical current for each battery set in the plurality of
battery sets; and configures, based on a determination of the
respective allocation, a respective electrical current flow through
each respective battery set to its respective allocation of
electrical current.
9. The apparatus of claim 8, further comprising: a battery
combination comprising at least one repurposed battery; and a power
grid interface coupling the battery combination with an electrical
power grid, wherein each at least one repurposed battery had been
used in an application different from exchanging electrical current
with an electrical power grid.
10. The apparatus of claim 9, wherein the battery combination
comprises: a first battery set having a first state of health when
the battery combination is assembled; and a second battery having a
second state of health when the battery combination is assembled,
the second state of health being different than the first state of
health.
11. The apparatus of claim 9, wherein the application comprises
providing electrical energy for an electrically powered
vehicle.
12. The apparatus of claim 8, further comprising a state of health
processor that, when operating, determines the respective state of
health for each respective battery set based upon a number of
charging and discharging cycles of each respective battery set.
13. The apparatus of claim 8, further comprising a state of health
processor that, when operating, determines the respective state of
health for each respective battery set based upon a combination of
a number of charging and discharging cycles of each respective
battery set and an age of each respective battery set.
14. The apparatus of claim 8, wherein the current division
controller, when operating, further receives a specification of: at
least one of: a total amount of electrical current to receive from
an external power system for charging the plurality of battery
sets, or a total amount of electrical current to provide to the
external power system, and wherein the respective allocation of
electrical current for each battery set is a respective percentage
of the total amount of electrical current.
15. The apparatus of claim 8, further comprising: an inverter
coupling the plurality of battery sets to an external power grid,
and wherein the inverter, when operating, exchanges, based on the
respective allocation, electrical power between the external power
grid and each battery set in the plurality of battery sets .
16. A computer program product for controlling electrical current
allocated to a plurality of battery sets, the computer program
product comprising: a computer readable storage medium having
computer readable program code embodied therewith, the computer
readable program code comprising instructions for: receiving a
respective state of health for each respective battery set in a
plurality of battery sets, the respective state of health
reflecting a respective present amount of total energy able to be
stored by each respective battery set relative to a specification
of the respective battery set; determining, based on the respective
state of health for each respective battery set, a respective
allocation of electrical current for each battery set in the
plurality of battery sets; and configuring, based on determining
the respective allocation, a current flow through each respective
battery set to its respective allocation of electrical current.
17. The computer program product of claim 16, wherein the plurality
of battery sets exchange electrical power with an electrical power
grid, and wherein the plurality of battery sets comprise at least
one repurposed battery, each at least one repurposed battery having
been used in an application different from exchanging electrical
current with an electrical power grid.
18. The computer program product of claim 17, wherein the plurality
of battery sets are part of an battery combination, the battery
combination comprising at least: a first battery set having a first
state of health when the battery combination is assembled; and a
second battery having a second state of health when the battery
combination is assembled, the second state of health being
different than the first state of health.
19. The computer program product of claim 17, wherein the
application comprises providing electrical energy for an
electrically powered vehicle.
20. The computer program product of claim 16, wherein the computer
readable program code further comprising instructions for receiving
a specification of: at least one of: a total amount of electrical
current to receive from an external power system for charging the
plurality of battery sets, and wherein the respective allocation of
electrical current for each battery set is a respective percentage
of the total amount of electrical current.
Description
FIELD OF THE DISCLOSURE
[0001] The present disclosure generally relates to controlling
utilization of auxiliary energy storage devices, and more
particularly to controlling the utilization of multiple
batteries.
BACKGROUND
[0002] In electrical power systems, managing and balancing power
consumption at a point in the system is able to use large
rechargeable battery systems to store and later provide electrical
energy. These batteries are able to be selected to provide electric
power to the grid or a particular load or premises on the grid
based upon a number of factors such as power demand and load
management factors. The rechargeable battery system includes
inverters and a control system for coupling the batteries to the
grid and for controlling the charging and discharging cycles of the
batteries.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The accompanying figures where like reference numerals refer
to identical or functionally similar elements throughout the
separate views, and which together with the detailed description
below are incorporated in and form part of the specification, serve
to further illustrate various embodiments and to explain various
principles and advantages all in accordance with the present
disclosure, in which:
[0004] FIG. 1 illustrates an example operational context for the
systems and methods described herein;
[0005] FIG. 2 illustrates a rechargeable battery system block
diagram, according to an example;
[0006] FIG. 3 illustrates a rechargeable battery system control
process, according to an example;
[0007] FIG. 4 depicts an energy storage battery subsystem
according, to one example;
[0008] FIG. 5 illustrates an electrical current division operation,
according to an example; and
[0009] FIG. 6 illustrates a block diagram illustrating a
controller, according to an example.
DETAILED DESCRIPTION
[0010] As required, detailed embodiments are disclosed herein;
however, it is to be understood that the disclosed embodiments are
merely examples and that the systems and methods described below
can be embodied in various forms. Therefore, specific structural
and functional details disclosed herein are not to be interpreted
as limiting, but merely as a basis for the claims and as a
representative basis for teaching one skilled in the art to
variously employ the disclosed subject matter in virtually any
appropriately detailed structure and function. Further, the terms
and phrases used herein are not intended to be limiting, but
rather, to provide an understandable description.
[0011] The terms "a" or "an", as used herein, are defined as one or
more than one. The term plurality, as used herein, is defined as
two or more than two. The term another, as used herein, is defined
as at least a second or more. The terms "including" and "having,"
as used herein, are defined as comprising (i.e., open language).
The term "coupled," as used herein, is defined as "connected,"
although not necessarily directly, and not necessarily
mechanically. The term "configured to" describes hardware, software
or a combination of hardware and software that is adapted to, set
up, arranged, built, composed, constructed, designed or that has
any combination of these characteristics to carry out a given
function. The term "adapted to" describes hardware, software or a
combination of hardware and software that is capable of, able to
accommodate, to make, or that is suitable to carry out a given
function.
[0012] The below described systems and methods control and manage
rechargeable battery systems that are used as auxiliary energy
sources in electrical power systems. In general, these systems and
methods operate to manage a number of batteries or battery sets
that are each able to be individually controlled or operated such
that each battery or battery set provides or accepts a determined
amount of electrical energy and all batteries or battery sets in
some examples are able to be combined in parallel to appear to
operate as a single battery.
[0013] The below descriptions described the operation of various
examples that control rechargeable battery systems that store and
retrieve energy in the form of electrical energy in one or more
batteries. The below described systems and method are also able to
be used in conjunction with any energy storing device, such as
other types of electrical energy storage devices. Further, it is
clear that these examples are able to operate with energy storage
devices that are able to store energy for any amount of time.
[0014] In electrical power systems, energy storage systems are able
to be large rechargeable battery systems that are able to be placed
in desired locations in the electrical power distribution system.
These rechargeable battery systems are able to receive and store,
and then later provide, electrical energy in order to manage and
balance power consumption at those locations. These rechargeable
battery systems are able to be controlled so as to provide electric
power to the grid or to a particular load or premises on the grid
based upon a number of factors such as power demand and load
management factors. The rechargeable battery systems in some
examples also include inverters and control systems for coupling
the batteries to the grid and for controlling the charging and
discharging cycles of the batteries. A cycle of providing
electrical energy to a battery in order to charge that battery, and
then drawing electrical energy from the battery to discharge the
battery is referred to herein as a "duty cycle."
[0015] A large rechargeable battery system is able to be made up of
a battery combination that has two or more battery sets. In an
example, a battery set includes a configuration of one or more
batteries that are connected together and that are operated in some
respects as a single battery. A particular battery set is able to
have only one battery, or a battery set is able to have any number
of batteries that are connected in any suitable arrangement to
provide electrical power. A number of battery sets are able to be
connected together with each other so that an increased amount of
electrical energy is available. In an example, a battery
combination is able to include a number of battery sets that are
configured to produce similar output voltages where all of the
battery sets are connected in a substantially parallel arrangement
so that each battery set receives or provides a portion of the
electrical current received or provided by the battery
combination.
[0016] In the following discussion, the term battery capacity
refers to a maximum amount of electrical energy that a particular
battery is able to store when it is fully charged. The battery
capacity of a particular battery degrades with usage and time. The
percentage of degradation is referred to a battery's "state of
health" or SOH. As a battery is charged and discharged and
generally ages, its capacity will continually decrease. As a
rechargeable battery is used, its capacity decreases due to this
degradation. Particular applications for rechargeable batteries may
define a minimum battery capacity and when the battery degrades to
the point that its capacity is below this minimum level, that
battery is no longer suitable for use in that application. When a
particular battery has degraded to the point that its capacity is
equal to that minimum battery capacity for its application, the
battery is said to have reached its "end-of-useful-life state of
health."
[0017] In a rechargeable battery system that has multiple battery
sets, it is often desirable for all batteries in the rechargeable
battery system to reach their end-of-useful-life state of health at
about the same time so that all batteries in the system may be
simultaneously replaced. If all batteries in a system start at an
equal state of health (e.g. 100% capacity), and the batteries are
equally charged and discharged, they will in general inherently
reach their end-of-useful-life state of health at about the same
time.
[0018] In some applications, it is desirable to build a
rechargeable battery system with a battery combination made up of
batteries that are not all at equal states of health. For example,
vehicle batteries from electrically powered vehicles such as
electric or hybrid cars or other vehicles may reach a depletion
level making them unacceptable for application in electric cars. In
an example, such batteries are said to have reached their "end of
useful life for a vehicle application" state of health. Although
operational considerations may decide that these batteries are no
longer suitable for a vehicle application, such batteries with that
state of health may be suitable for use in rechargeable battery
system to be used in other applications, such as in a power grid
load management application. In an example, these batteries are
able to be repurposed for inclusion in such as rechargeable battery
system that is used in a power grid load management
application.
[0019] A battery that has been used in one application is able to
be physically removed from that application and become a repurposed
battery that is assembled into a battery combination within a
rechargeable battery system. In an example, a battery used to power
an electrically powered vehicle, which is an application that is
different from exchanging electrical current with an electrical
power grid. Such a battery is able to be removed from the
electrically powered vehicle and repurposed to become a repurposed
battery that is used to store energy and exchange electrical
current with an electrical power grid.
[0020] In general, a battery combination is able to be assembled
using a number of battery sets where some of the battery sets have
all new batteries, and other battery sets have repurposed batteries
that have some degradation in their state of health. In some of
these examples, the repurposed batteries have reduced battery
capacities at the time that the battery combination is assembled
and the rechargeable battery system with that battery combination
is put into service. For various reasons, the states of health of
each battery set that includes such repurposed batteries is able to
vary significantly from one another when these battery sets are
first assembled into one battery combination.
[0021] The below described systems and methods operate to more
effectively manage a rechargeable battery system containing a
battery combination that is assembled from a number of battery sets
where the different battery sets in the battery combination are
able to have a different state of health when the rechargeable
battery system with that battery combination is assembled and put
into service. In an example, the charging and discharging cycle for
each battery set in the rechargeable battery system is
independently managed. The amount of energy exchanged with each
battery set in some examples is individually varied based on the
present state of heath, or the present capacity, of that battery
set. The amount of energy exchanged with a battery set includes the
amount of electrical current provided to charge the battery set and
the amount of electrical current drawn from the battery set.
[0022] The amount of energy exchanged with a particular battery set
in an example is based on the state of health of that battery set
relative to the other battery sets in the rechargeable battery
system. In an example, the amount of energy exchanged with each
battery set in the rechargeable battery system is controlled over
all charging and discharging cycles with the goal of causing all
battery sets in the rechargeable battery system to substantially
reach end-of-useful-life state of health at about the same time.
Because all battery sets in the rechargeable battery system are
operated in a manner that causes all battery sets to reach their
end-of-useful-live state of health at about the same time, all
batteries in the rechargeable battery system are able to be
replaced together.
[0023] In an example, a controller causes battery sets with higher
states of health to have more intense charge and discharge duty
cycles than battery sets with lower states of health. In various
examples, more intense charge and discharge duty cycles are able to
include charging and discharging the battery set more often, at
greater magnitudes, using the battery set in more intense manners,
or combinations of these.
[0024] In an example, the state of health of each battery set is
determined and monitored at various times. In an example, the state
of health of each battery set is determined and updated by
processing during operation of the rechargeable battery system. In
general, battery sets with any state of health can be accommodated
when assembling those battery sets into a rechargeable battery
system. The determined present state of health for each battery set
is used in an example during the operation of a rechargeable
battery system to determine the charge and discharge duty cycle to
use for each battery set relative to the charge and discharge duty
cycle of other battery sets in the rechargeable battery system. In
an example, a controller tracks the state of health of each battery
set as the battery sets cycle through their charge and discharge
duty cycles. The determining and monitoring of the state of health
of each battery set may be through any approach. In an example, the
below described examples provide for a uniform depletion of battery
sets that each have variable states of health at the time of their
installation into their rechargeable battery system.
[0025] In an example, the battery combination within a rechargeable
battery system is able to be assembled with batteries, battery
sets, or combinations of these that have different states of health
at the time the rechargeable battery system is assembled. For
example, a battery combination is able to be assembled with at
least a first battery set, which has a first state of health, and a
second battery set, which has a second state of health that is
different from the first state of health. In such an example this
state of health at the time of assembly is considered in
determining a respective duty cycle for each of these battery sets
when operating the rechargeable battery system.
[0026] FIG. 1 illustrates an example operational context 100 for
the systems and methods described herein. The example operation
context 100 is an example of an electrical power "grid" that is
used to provide electrical power to consumer premises 172. The
below described systems and methods include storage subsystems,
such as the illustrated energy storage system 122, that is able to
be deployed to various locations within the electrical power grid.
In various examples, these energy storage subsystems are or include
rechargeable battery systems that are able to be deployed at
various points within an electrical power transmission or
distribution system. These energy storage systems 122 are able to,
for example, support load management or other operational goals.
The example operational context 100 depicts an energy storage
system 122 that is deployed to, and operates in conjunction with, a
substation 120 in an electrical power grid.
[0027] The example operational context 100 depicts a number of
example power generation components 170. Illustrated are a combined
cycle gas generator 102, a solar array farm 104, and a wind farm
106. In further examples, operational contexts are able to include
one power generation component, multiple collocated power
generation components, power generation components that are
physically separated and supply a common electrical power
transmission or distribution system, any one or more power
generation components, or combinations of these. These power
generation components are able to be of any suitable type or
design.
[0028] In the example operational context 100, electrical power
generated by one or more power generation components is provided to
a power transmission system 110. The illustrated example
operational context 100 depicts a transmission connection 108 that
couples one or more sources within power generation components 170
to the power transmission system 110. The transmission connection
108 and power transmission system 110 in an example include
suitable step-up transformers and long distance transmission lines
to convey the generated electrical power to remote power
distribution networks, other electrical power consumers, or
both.
[0029] The illustrated power transmission system 110 provides
electrical power to a substation 120. The substation 120 includes
transformers, protection devices, and other components to provide
electrical power to a power distribution system 130.
[0030] In the example operational context 100, the substation 120
further includes an energy storage system 122 that receives
electrical energy from the substation in this example, stores that
energy, and then provides the stored energy to the substation for
delivery to the power distribution system 130. In an example, the
energy storage system 122 is able to be controlled to, at different
times, either selectively receive and store electrical energy, or
to provide stored electrical energy. Determining whether and how
much electrical energy the energy storage system 122 is to receive
or provide, or whether the energy storage system is not to exchange
any electrical current, is able to be controlled according to the
operation needs such as supporting present power demands,
supporting load management functions, or based on other
considerations.
[0031] The energy storage system 122 in an example is a
rechargeable battery system that is assembled from a number of
batteries or battery sets 124. The energy storage system 122 stores
electric energy received from the transmission system 110 and
provides electric energy to a power distribution system 130. The
energy storage system 122 may include a plurality of batteries or
battery sets 124 that are assembled into an enclosure, such as a
metal shipping container, for easy transportation and installation
at a substation or other location.
[0032] An electrical power grid in general operates to deliver
power produced by the generating components 170 to customer
premises, such as the illustrated home 140 or office building 150.
In general customer premises are coupled to the power distribution
system 130 and are able to include any combination of residential,
commercial or industrial buildings.
[0033] A first vehicle 142 and a second vehicle 152 are examples of
electrically powered vehicles. In an example, the first vehicle 142
or the second vehicle 152 are able to be electric or hybrid
vehicles that each have batteries and may be used to commute
between customer premises or any other location. These electric or
hybrid vehicles may further couple to the premises to through
connectors 144, 154 to recharge their batteries for use in powering
these electrical vehicles.
[0034] The battery in these electric or hybrid vehicles degrade
over time and usage. The reduced total energy storage capacity of
these degraded batteries directly reduces the usable range of the
vehicle. It is generally desired to replace the batteries in an
electric or hybrid vehicle when they degrade to a point that
reduces the vehicle's usable range to below an acceptable
threshold. This point is referred to as an end of useful life for
the battery in a vehicle application.
[0035] Although it may be desirable to replace batteries in an
electric or hybrid vehicle when they reach a certain state of
health, these degraded batteries may have considerable usefulness
when repurposed for use in an energy storage system 122 within an
electrical power grid. In an example, degraded batteries from an
electric or hybrid vehicles are able to be removed and installed
160 into the energy storage system 122. Batteries installed in an
energy storage system 122 for use in an electrical power grid may
be repurposed from any of a number of applications, such as
batteries from electric or hybrid vehicle applications. In addition
to repurposed batteries, some electrical storage systems may be
assembled with some new batteries in addition to repurposed
batteries.
[0036] Partially degraded batteries that are repurposed and
installed 160 in an energy storage system 122, however, will have
varying states of health due use the degradation incurred by these
repurposed batteries during their prior applications. In order to
improve the utility of an energy storage system 122 that is
assembled with a number of repurposed batteries that may have
different states of health, the utilization of each battery or each
set of batteries in the energy storage system is able to be
individually managed so as to cause all of the batteries in the
energy storage system 122 to reach their end of useful life for an
electrical power grid application at about the same time. Such
management will vary the amount of utilization of each of the
component batteries or battery sets based on the present state of
health of the particular battery or battery set. Managing each
battery or battery set in the energy storage system 122 in such a
manner allows all batteries in the energy storage system 122 to
reach their individual end of useful life for an electrical power
grid application at the same time. Such management of the operation
the energy storage system 122 increases the efficiency and cost
effectiveness of replacing or rebuilding the energy storage system
122 because such replacement or rebuilding is performed when all of
the batteries or battery sets within the energy storage system have
reached their end of useful life.
[0037] FIG. 2 illustrates a rechargeable battery system block
diagram 200, according to an example. The rechargeable battery
system block diagram 200 is an example of an energy storage system
122 and is able to be utilized as an auxiliary power source placed
at any suitable location in an electrical power grid. In general,
the rechargeable battery system block diagram 200 depicts a
rechargeable battery system with a battery combination that
consists of a number of battery sets that are able to operate in
conjunction with one another to receive electrical energy from a
source, store that electrical energy, and later provide that
electrical energy to a consumer of electrical power.
[0038] The rechargeable battery system block diagram 200 depicts
three battery sets, a battery set A 204, a battery set B 206, and a
battery sent N 208. These three battery sets are illustrated as an
example and other rechargeable battery systems are able to use any
number of battery sets. The one or more batteries, battery sets,
other energy storage devices, or combinations of these are
generally referred to herein as a battery combination. In general,
a battery set is able to consist of one or more batteries and is
able to include multiple batteries that are able to be connected so
as to operate as a single energy storage device to receive energy
to store and then later provide that energy to a load.
[0039] Each battery set in the rechargeable battery system block
diagram 200 has an associated monitor. Battery set A 204 is
associated with a monitor A 214, battery set B 206 is associated
with a monitor B 216, and battery set N 208 is associated with a
monitor N 218. In general, each of these monitors determines a
present remaining battery capacity for its associated battery. In
the present discussion, remaining battery capacity reflects
degradation of the battery set and the reduction in total energy
that is able to be stored in a fully charged battery due to aging
and repeated charging and discharge cycling. In an example,
remaining battery capacity is expressed as a percentage of the
total energy that the fully charged battery set is able to store
relative to the specification of a total amount of energy that
battery set is specified to store. In an example, this
specification reflects the amount of energy the battery set could
store when it was new. Examples of a monitor suitable to operate as
the monitor A 214, the monitor B 216, or the monitor N 218, is
described in commonly owned U.S. patent application Ser. No.
15/095,693, entitled "STEP-TIME BATTERY DEGRADATION DETERMINATION,"
filed on Apr. 11, 2016, the entire contents and teachings of which
are hereby incorporated herein by reference.
[0040] Each battery set is connected in series with an associated
current control device. Battery set A 204 is connected in series
with a current control A 224, battery set B 206 is in series with
current control B 226, and battery set N 208 is in series with
current control N 228. In general, each of these current control
devices is able to be configured to control an amount of electrical
current flowing through its associated battery set as well as the
direction of that current flow. In an example, each current control
device is able be configured to allow electrical current to flow
into its associated battery set in order to charge that battery
set, or to allow electrical current flow out of the battery set in
order to discharge that battery set and provide energy stored in
that battery set to be delivered to external systems as is
described below.
[0041] In various examples, these current control devices, such as
current control A 224, current control B 226, or current control C
228, are able to control current flow by any suitable technique. In
some examples, these current control devices are able to switch
current flow off and on for determined intervals to achieve a total
current flow over these determined intervals that correspond to the
configured current flow that is to flow through its associated
battery set. In some examples, these current control devices are
able to set an output current limit that corresponds to the
configured current flow for its associated battery set. In general,
these current control devices are able to use one or any
combination of multiple current flow limiting operations to control
the electrical current that flows through its associated
battery.
[0042] The current control devices are each configured to receive
electrical current from, or provide electrical current to, an
inverter 230. The inverter 230 is an example of a power grid
interface that couples the above described battery combination with
an electrical power grid. The inverter 230 is able to be any
suitable device that supports exchanging electrical current between
the battery sets of the rechargeable battery system block diagram
200 and external power systems such as the illustrated power grid
232. In a further example, the inverter 230 is able to act as a
current control device for one or more battery sets. In such
examples, one or more battery sets are connected to an inverter
without an intervening current control device. Further, in some
examples, each battery set is able to be connected to its own
inverter.
[0043] The rechargeable battery system block diagram 200 includes a
total current control 234. The total current control 234 in an
example is a source of a specification of a total amount of
electrical current that is to be provided by, or that is to be
received, by the rechargeable battery system illustrated in the
rechargeable battery system block diagram 200. In various examples,
the total current control 234 provides a specification of an amount
of electrical current that the rechargeable battery system is to
provide to the illustrated power grid 232, a specification of an
amount of electrical current to be taken from the power grid 232
for use in charging the battery sets of the rechargeable battery
system, a specification that the rechargeable battery system is to
remain idle and not provide or receive any electrical energy to or
from the power grid 232, any other specification, or combinations
of these. In general, the total current control 234 is able to be
any suitable source of such control signals, such as a
communications interface to a remote controlling function, a
processor that implements various algorithm or applies other rules
to various inputs to determine a total current control
specification for the rechargeable battery system, other sources,
or combinations of these.
[0044] The rechargeable battery system block diagram 200 includes a
current division controller 202 that provides control signals to
each current control device, such as current control A 224, current
control B 226, and current control N 228, to specify the individual
amounts of electrical current that are to flow through each
associated battery set and also the direction of that electrical
current flow.
[0045] The current division controller 202 receives information
regarding each battery set from the monitor associated with that
battery set. For example, the illustrated current division
controller 202 receives status characterizations for battery set A
204 from monitor A 214, status characterizations for battery set B
206 from monitor B 216, and status characterizations for battery
set N 208 from monitor N 218. These characterizations include but
are not limited to, for example, the present state of health or
capacity of each of these battery sets which reflects the
degradation to each of these battery sets over time due to age and
use by charging and recharging. As is described below, the current
division controller 202 determines an amount of electrical current
that is to flow through each battery set and commands the
associated current control device to cause that amount of
electrical current to flow through its associated battery set.
[0046] FIG. 3 illustrates a rechargeable battery system control
process 300, according to an example. This description of the
rechargeable battery system control process 300 include references
to the rechargeable battery system block diagram 200 described
above. The rechargeable battery system control process 300 is an
example of a process performed by the current division controller
202 described above. The rechargeable battery system control
process 300 in an example configures each battery set in a
rechargeable battery system to receive or provide a specified
amount of electrical current based on its capacity relative to the
capacity of other battery sets in the rechargeable battery
system.
[0047] The rechargeable battery system control process 300 beings
by receiving, at 302, a state of health for each battery set. The
state of health in an example is specified as a percentage of the
total amount of electrical energy that is able to be stored in a
particular battery set relative to the total amount of electrical
current specified for that particular battery set, such as the
amount of energy it could store when it was new and had not
degraded due to time and use. In an example, the state of health of
each battery set is received from the monitors described above,
such as monitor A 214, monitor B 216, or monitor N 218.
[0048] The rechargeable battery system control process 300
receives, at 304, a total of electrical current amount
specification that the rechargeable battery system is to provide or
receive. In an example this total amount of electrical current is
specified by a source or algorithm. The total current control 234
described above is an example of a source from which this
specification of the total amount of electrical current is able to
be received.
[0049] A portion of the received total electrical current amount to
allocate to each battery set in the rechargeable battery system is
determined, at 306. This allocation is able to be made based upon
the state of health of each battery set relative to other battery
sets in the rechargeable battery system.
[0050] In one example, the allocation of electrical current to each
battery set is based on the present state of health or remaining
capacity of each battery set relative to the state of health or
remaining capacity of the other battery sets. In one example, the
state of health of a battery set is specified as a percentage of
total energy that the battery set is presently able to store when
filly charged as compared to a specification of the amount of
energy that battery set can store, such as the amount of energy it
could store when that battery set was new. For example, a 1,000
Amp-Hour battery set that has a present state of health or present
capacity of 80% will store 800 Amp-Hours when fully charged.
[0051] The allocation of electrical current in one example is able
to be based on a simple proportion of the present capacity of each
patter to a total of all of the present capacity percentages for
all of the battery sets. In an example, the electrical current to
flow through a battery set A (I.sub.A)is given by an equation:
I.sub.A=I.sub.totalSOH.sub.A/.SIGMA.SOH.sub.i where I.sub.total is
the total amount of current to allocate to all battery sets, and
.SIGMA.SOH.sub.i is the sum of the SOH percentages for all battery
sets. In this example, the denominator of this equation may be
greater than 100.
[0052] Each battery set is then configured, at 308, to provide or
receive its determined portion of the total electrical current to
be provided or received by the rechargeable battery system. In an
example, configuring a particular battery set to provide this
portion of electrical current is perform by sending control signals
to the current control device that is in series with that
particular battery set. For example, setting the amount of
electrical current to be provided or received by battery set A 204
is performed by controlling current control A 224 to cause that
portion of electrical current to flow through battery set A
204.
[0053] A determination is made, at 310, if the electrical current
settings for the battery sets are to be re-evaluated. This
re-evaluation is able to be based on, for example, receiving a new
total electrical current amount command, receiving a new estimate
of state of health or capacity for one or more battery sets, based
on a configured time interval for re-evaluation of these
parameters, based on any other event, or based on combinations of
these. If this determination repeats until it is determined that
this re-evaluation is to be performed. Once this re-evaluation is
determined to be performed, the state of health of each battery set
is determined, at 302, and the above described processing is
repeated.
[0054] FIG. 4 depicts an energy storage battery subsystem 400
according to one example. The energy storage battery subsystem 400
depicts a configuration of a single battery set, such as battery
set A 204, in conjunction with an inverter 230 and its connection
to the power grid 232. The battery 402 in this example is able to
be a single battery or a combination of several batteries connected
to so as to operate and be treated as a single battery. In an
example, the battery 402 is equivalent to one battery set such as
those described above.
[0055] The battery 402 is connected to the inverter 230 through a
current controller 420 as is described above with regards to, for
example, battery set A 204 and current control A 224. The inverter
230, as described above, exchanges energy between the battery 402
and the power grid 232. The power grid 232 in this example is an
example of an external power system. The battery 402 in this
example is able to periodically provide electric power through the
inverter 230 to the power grid 232, or to a particular load or
premises on the grid in further examples, based upon a number of
factors including demand and load management factors. The current
controller 420 in an example receives a control 430 specifying the
direction and amount of electrical current that is to flow through
the battery 402, and thus controls the charging and discharging
cycles of the battery 402.
[0056] The energy storage battery subsystem 400 includes a state of
charge (SOC) monitor 408 that operates to monitor the operation of
the battery 402 and determine an estimate of the amount of charge
in the battery, which corresponds to the energy remaining in the
battery, at a given time. The state of charge monitor 408 provides
the present state of charge output 432 to any suitable
destination.
[0057] The battery 402 in this example is connected in a parallel
configuration with a voltmeter 406. Voltmeter 406 measures and
reports output voltages of the battery 402. The voltmeter 406 is
able to measure the instantaneous voltage across the battery 402.
The voltmeter 406 in this example reports the instantaneous output
voltage of the battery to the state of charge monitor 408. The
battery 402 and voltmeter 406 in some examples are able to be
connected in a substantially parallel configuration and with either
direct or indirect couplings. Indirect connections are able to
include, as an example, resistive components, reactive components,
active components, or combinations of these.
[0058] The battery 402 is further connected in series with an
ammeter 404. The ammeter 404 in an example continuously monitors
the electrical current passing through the battery 402 and reports
these readings to the state of charge monitor 408. The battery 402
and ammeter 404 in one example may be in a substantially series
configuration such that all or nearly all of the current that
passes through one component passing through the other.
[0059] The state of charge monitor 408 in one example is a
dedicated processor or a computing process within a general purpose
processor that receives, assembles and processes battery status
data to determine or estimate the present state of charge of the
battery 402. In an example, the state of charge monitor estimates
the state of charge present in the battery is determined based on
the battery output voltage measurements received from the voltmeter
406 and the electrical current measurements received from ammeter
404. In an example, electrical current drawn from or provided to
the battery 402 is integrated and this integrated value is used as
a basis for determining the state of charge of the battery 402.
[0060] In an example, the state of charge monitor 408 is also able
to determine the charging state of the battery 402. The charging
state of the battery 402 in an example is able to be one of that
the battery is in a state of being charged, being discharged, or
the battery is idle without appreciable current flowing
therethrough. In an example, the charging state of the battery is
able to be determined by the present direction of current flow
through the battery 402, where current into the battery indicates
that the battery is being charge, current being drawn from the
battery indicates that the battery is being discharged, and
substantially no current through the battery indicated that the
battery is idle.
[0061] As described above, the maximum amount of energy that a
battery is able to store when the battery is fully charged is
referred to as the battery's present capacity and decreases with
usage and time. The state of health of a battery refers to the
amount of degradation in the amount of total energy that a battery
is able to store, i.e., a reduction in the battery capacity. The
percentage of degradation is referred to a battery's "state of
health." A degradation model processor 410 is an example of a state
of health processor that determines the present state of health of
the battery 402. The degradation model processor 410 is an example
of a state of health (SOH) processor that is able to determine the
state of health (SOH), which is equivalent to the present capacity,
of the battery 402. The degradation model processor 410 in various
examples is able to use any technique to determine or estimate the
present state of health, or remaining capacity, of the battery 402.
In an example, the state of charge monitor 408 provides both an
indication the charging state of the battery 402 and the estimated
present state of charge of the battery 402 to support a
determination of the present state of health of the battery 402.
The degradation model processor 410 monitors the operation of the
battery 402 as measured by the voltmeter 406 and ammeter 404 over
time and applies a degradation model using these measurements to
determine the present remaining capacity of the battery 402.
[0062] The state of charge monitor 408 and degradation model
processor 410 both monitor, accumulate and process measured values
and determined values and conditions over various time durations.
The degradation model processor 410 in an example determines the
remaining capacity of the battery 402 based on observed charging
states and electrical current flowing through the battery 402 over
time. The energy storage battery subsystem 400 includes a time
source 412 to provide this time to these components to support
their operation. An example of a degradation model processor 410 is
described in commonly owned U.S. patent application Ser. No.
15/095,693, entitled "STEP-TIME BATTERY DEGRADATION DETERMINATION"
filed on Apr. 11, 2016, the entire contents and teachings of which
are hereby incorporated herein by reference.
[0063] FIG. 5 illustrates an electrical current division operation
500, according to an example. The electrical current division
operation 500 illustrates how a total amount of electrical current
is divided between two batteries according to the relative capacity
or state of health of each battery compared to the other. This
description refers to two batteries to simplify the description and
presentation of the certain aspects. In general, these principles
are able to be directly applied to any rechargeable battery system
with any number of any suitable type of batteries including single
batteries or battery sets consisting of multiple batteries.
[0064] The electrical current division operation 500 depicts how a
total electrical current amount is divided between two batteries, a
battery A and a battery B. In this example, battery A is estimated
to have a State Of Health (SOH) of 80%. The SOH of 80% indicates
that when battery A is fully charged, it stores only 80% of the
total amount of energy that it could store when it was fully
charged when it was new. Battery B in this example is estimated to
have an SOH of 50%.
[0065] In this example, the allocation of electrical current
between the two batteries is based on the ratio of the present
capacity of each battery to the total of the present capacity of
both of these batteries. Given the above described capacities of
battery A and battery B being 80% and 50%, respectively, the total
of these capacities is 220. Using the allocation technique
described above with regards to energy storage battery subsystem
400, battery A has an allocation of 80/120 or 2/3 times the total
electrical current for the rechargeable battery system. Battery B
has an allocation of 50/120, or 1/3 times the total electrical
current for the rechargeable battery system. It is clear that this
proportion is able to be calculated in further examples using any
number of batteries.
[0066] Any operation of a respective current controller for battery
A and battery B can be used to cause these amounts of electrical
current to pass through these batteries. An electrical current flow
diagram 502 depicts the operation of an "on-off" current controller
for each of battery A and battery B in this example. In the
illustrated example, the rechargeable battery system is to provide
an electrical current T to an inverter and out to power consumers.
This total electrical current amount T is allocated between battery
A and battery B according to the relative capacities of these
batteries as is described below. This illustrated example is
provided as one example of a technique to allocate electrical
current between two batteries. In general, any other suitable
technique is able to be used.
[0067] The horizontal axis of the electrical current flow diagram
502 depicts a time scale with time marks indicating uniform time
intervals. Time interval 0 530 depicts time 0, time interval 1 532
depicts time 1, time interval 2 534 depicts time 2, time interval 3
536 depicts time 3, time interval 4 538 depicts time 4, and time
interval 5 540 depicts time 5. The vertical axis indicates
electrical current being provided by each battery. Current flow for
battery A is shown to vary between an off level 522, where i=0, and
an on level 520, where i=T. Electrical current flow for battery B
is also shown to vary between an off level 526, where i=0, and an
on level 524, where i=T.
[0068] The electrical current flow diagram 502 depicts a battery A
current flow vs time 504 and a battery B current flow vs. time 506.
In this example, each of battery A and battery B are configured to
alternately have the total amount of electrical current that is
specified to flow through the rechargeable battery system. The time
intervals that each battery provides this current is varied to
allocate the average amount of current flowing through each battery
according to the determined allocation.
[0069] The battery A current flow vs time 504 indicates that
battery A provides, during a first phase 510, the total amount of
current (T) for two time intervals, i.e., from time 0 530 to time 2
534. Battery A provides no current during a second phase 512
between time 2 534 and time 3 536. Battery A then continues to
provide current T during a third phase 514 for two time intervals
between time 3 536 and time 5 540.
[0070] The battery B current flow vs time 506 indicates that
battery B provides no electrical current for two time intervals,
from time 0 530 to time 2 534, during a first phase 516. Battery B
provides current T for one time interval during a second phase 518
between time 2 534 and time 3 536. Battery B then provides no
current during a third phase 519 for two time intervals between
time 3 536 and time 5 540.
[0071] FIG. 6 illustrates a block diagram illustrating a controller
600 according to an example. The controller 600 is an example of a
processing subsystem that is able to perform any of the above
described processing operations, control operations, other
operations, or combinations of these.
[0072] The controller 600 in this example includes a CPU 604 that
is communicatively connected to a main memory 606 (e.g., volatile
memory), a non-volatile memory 612 to support processing
operations. The CPU is further communicatively coupled to a network
adapter hardware 616 to support input and output communications
with external computing systems such as through the illustrated
network 630.
[0073] The controller 600 further includes a data input/output
(I/O) processor 614 that is able to be adapted to communicate with
any type of equipment, such as the illustrated system components
628. The data input/output (I/O) processor in various examples is
able to be configured to support any type of data communications
connections including present day analog and/or digital techniques
or via a future communications mechanism. A system bus 618
interconnects these system components.
[0074] Information Processing System
[0075] The present subject matter can be realized in hardware,
software, or a combination of hardware and software. A system can
be realized in a centralized fashion in one computer system, or in
a distributed fashion where different elements are spread across
several interconnected computer systems. Any kind of computer
system--or other apparatus adapted for carrying out the methods
described herein--is suitable. A typical combination of hardware
and software could be a general purpose computer system with a
computer program that, when being loaded and executed, controls the
computer system such that it carries out the methods described
herein.
[0076] The present subject matter can also be embedded in a
computer program product, which comprises all the features enabling
the implementation of the methods described herein, and which--when
loaded in a computer system--is able to carry out these methods.
Computer program in the present context means any expression, in
any language, code or notation, of a set of instructions intended
to cause a system having an information processing capability to
perform a particular function either directly or after either or
both of the following a) conversion to another language, code or,
notation; and b) reproduction in a different material form.
[0077] Each computer system may include, inter alia, one or more
computers and at least a computer readable medium allowing a
computer to read data, instructions, messages or message packets,
and other computer readable information from the computer readable
medium. The computer readable medium may include computer readable
storage medium embodying non-volatile memory, such as read-only
memory (ROM), flash memory, disk drive memory, CD-ROM, and other
permanent storage. Additionally, a computer medium may include
volatile storage such as RAM, buffers, cache memory, and network
circuits. Furthermore, the computer readable medium may comprise
computer readable information in a transitory state medium such as
a network link and/or a network interface, including a wired
network or a wireless network, that allow a computer to read such
computer readable information. In general, the computer readable
medium embodies a computer program product as a computer readable
storage medium that embodies computer readable program code with
instructions to control a machine to perform the above described
methods and realize the above described systems.
Non-Limiting Examples
[0078] Although specific embodiments of the subject matter have
been disclosed, those having ordinary skill in the art will
understand that changes can be made to the specific embodiments
without departing from the spirit and scope of the disclosed
subject matter. The scope of the disclosure is not to be
restricted, therefore, to the specific embodiments, and it is
intended that the appended claims cover any and all such
applications, modifications, and embodiments within the scope of
the present disclosure.
* * * * *