1. An apparatus for diagnosing a state of a battery pack, comprising: a charging and discharging unit configured to discharge and charge a plurality of battery modules having a plurality of battery cells connected to each other, in a plurality of cycles; a monitoring unit configured to measure a voltage or current of the plurality of completely charged battery modules, in every cycle; and a control unit configured to, in every cycle, change the number of battery cells included in the plurality of battery modules and connected to each other, receive a measurement value for the voltage or current of the plurality of battery modules measured by the monitoring unit, estimate a state of charge (SOC) of each of the plurality of battery modules based on the received measurement value, calculate a SOC change amount by comparing the estimated SOC of each of the plurality of battery modules with a preset reference value, and diagnose a state of the plurality of battery modules based on the calculated SOC change amount and the changed number of battery cells.

2. The apparatus for diagnosing a state of a battery pack according to claim 1, wherein the control unit is configured to, in every cycle, select a target module among the plurality of battery modules, select a target cell among the plurality of battery cells included in the selected target module, and block a connection between the target cell and the remaining cells in the selected target module.

3. The apparatus for diagnosing a state of a battery pack according to claim 2, wherein the control unit is configured to select the target module in every cycle such 45 that the selected target module does not overlap with a target module selected in a former cycle.

4. The apparatus for diagnosing a state of a battery pack according to claim 2, wherein the control unit is configured to, in every cycle, change the number of target cells selected in the target module.

5. The apparatus for diagnosing a state of a battery pack according to claim 2, wherein the charging and discharging unit is configured to discharge and charge battery cells connected to each other among the plurality of battery cells included in the battery module.

6. The apparatus for diagnosing a state of a battery pack according to claim 1, wherein the control unit is configured to diagnose the state of the battery module as a normal state or a warning state according to a range to which the calculated SOC change amount belongs, among a plurality of reference ranges set based on the number of total battery cells included in the battery module, and output the diagnosis result.

7. The apparatus for diagnosing a state of a battery pack according to claim 6, wherein the control unit is configured to block the connection between the battery pack and the battery module whose state is diagnosed as the warning state, re-estimate the SOC of the battery module disconnected from the battery pack after a predetermined time passes, compare the re-estimated SOC with the predetermined reference value, and output a diagnosis code based on the comparison result. 46

8. A battery pack, comprising the apparatus for diagnosing a state of a battery pack according to any one of claims 1 to 7.

9. A method for diagnosing a state of a battery pack, comprising: a charging and discharging step of discharging and charging a plurality of battery modules having a plurality of battery cells connected to each other, in every cycle; a monitoring step of measuring a voltage or current of the completely charged battery modules; a SOC estimating step of estimating a SOC of each battery module based on the voltage or current measured in the monitoring step; a SOC change amount calculating step of calculating a SOC change amount by comparing the estimated SOC of each battery module with a preset reference value; and a diagnosing step of diagnosing a state of the battery modules based on the calculated SOC change amount.

10. The method for diagnosing a state of a battery pack according to claim 9, before the charging and discharging step, further comprising: a target module selecting step of selecting a target module among the plurality of battery modules; a target cell selecting step of selecting a target cell among the plurality of battery cells included in the selected target module; and a connection blocking step of blocking the connection between the target cell and the remaining cells in the selected target module.

11. The method for diagnosing a state of a battery pack according to claim 9, wherein the diagnosing step includes: a battery module state determining step of determining the state of the battery module as any one of a normal state and a warning state, based on a range to which the calculated SOC change amount belongs, among a plurality of reference ranges set based on the number of total battery cells included in the battery module; a battery module connection blocking step of blocking the connection between the battery module determined as the warning state and the battery pack, as a result of the determination in the battery module state determining step; a SOC re-estimating step of re-estimating the SOC of the battery module disconnected from the battery pack, after a predetermined time passes from the battery module connection blocking step; and a diagnosis code outputting step of comparing the re-estimated SOC with a predetermined reference value and outputting a diagnosis code based on the comparison result.

FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
“DEVICE AND METHOD FOR DIAGNOSING STATE OF
BATTERY PACK”
LG ENERGY SOLUTION, LTD., of Tower 1, 108, Yeoui-daero,
Yeongdeungpo-gu, Seoul 07335, Republic of Korea
The following specification particularly describes the invention and the manner in
which it is to be performed.
2
DEVICE AND METHOD FOR DIAGNOSING STATE OF BATTERY PACK
TECHNICAL FIELD
The present application claims priority to Korean Patent Application No. 10-2019-
0083361 filed on July 10, 2019 in the Republic of Korea, the disclosures of which are
incorporated herein by reference.
The present disclosure relates to an apparatus and method for diagnosing a state of a
battery pack, and more particularly, to an apparatus and method for diagnosing a state of a
battery pack based on a SOC of a battery module included in the battery pack.
BACKGROUND ART
Recently, the demand for portable electronic products such as notebook computers,
video cameras and portable telephones has increased sharply, and electric vehicles, energy
storage batteries, robots, satellites and the like have been developed in earnest. Accordingly,
high-performance batteries allowing repeated charging and discharging are being actively
studied.
Batteries commercially available at the present include nickel-cadmium batteries,
nickel hydrogen batteries, nickel-zinc batteries, lithium batteries and the like. Among them,
the lithium batteries are in the limelight since they have almost no memory effect compared
to nickel-based batteries and also have very low self-discharging rate and high energy density.
Meanwhile, a large-capacity battery used in an electric vehicle, a hybrid electric
vehicle or an energy storage system includes an aggregate of a plurality of unit cells
connected in series and/or in parallel. The battery in which a plurality of unit cells are
connected has a variation in charging capacity between the unit cells, as charging and
discharging are repeated. If charging or discharging is continued in a state of leaving the
3
variation in charging capacity, performance is degraded, and some unit cells may come into
an overcharge or overdischarge state. The overcharge or overdischarge state acts as a factor
that impairs the safety of the unit cell, and in some cases, may cause an unexpected accident
such as an explosion.
In order to solve the above problem, techniques for diagnosing a state of a battery
pack have been developed in the prior art. For example, Patent Literature 1 discloses a
battery management device that estimates a state of charge (SOC) of each battery module and
determines that the battery module is abnormal if the deviation of the SOC estimated for each
battery module is equal to or greater than a limit deviation, and a battery management method
using the same.
Specifically, in Patent Literature 1, the SOC of each battery module is estimated, and
abnormality of the battery module or the battery management device itself is recognized
based on the deviation of the estimated SOC.
However, in Patent Literature 1, the SOC of the battery module is just estimated, and
abnormality of the battery module or the battery management device itself is just recognized
based on the deviation of the estimated SOC. Namely, Patent Literature 1 does not disclose
a configuration for inducing an abnormal situation such as cutoff of a battery cell included in
the battery module and diagnosing a state of the battery module in the induced abnormal
situation.
(Patent Literature 1) KR 10-1642329 B1
DISCLOSURE
Technical Problem
The present disclosure is designed to solve the problems of the related art, and
4
therefore the present disclosure is directed to providing an apparatus and method for
diagnosing a state of a battery pack, which blocks the connection of some of battery cells
included in a battery module provided in the battery pack and diagnoses a state of the battery
module and the battery pack based on a SOC of the battery module.
These and other objects and advantages of the present disclosure may be understood
from the following detailed description and will become more fully apparent from the
exemplary embodiments of the present disclosure. Also, it will be easily understood that the
objects and advantages of the present disclosure may be realized by the means shown in the
appended claims and combinations thereof.
Technical Solution
In one aspect of the present disclosure, there is provided an apparatus for diagnosing
a state of a battery pack, comprising: a charging and discharging unit configured to discharge
and charge a plurality of battery modules having a plurality of battery cells connected to each
other, in a plurality of cycles; a monitoring unit configured to measure a voltage or current of
the plurality of completely charged battery modules, in every cycle; and a control unit
configured to, in every cycle, change the number of battery cells included in the plurality of
battery modules and connected to each other, receive a measurement value for the voltage or
current of the plurality of battery modules measured by the monitoring unit, estimate a state
of charge (SOC) of each of the plurality of battery modules based on the received
measurement value, calculate a SOC change amount by comparing the estimated SOC of
each of the plurality of battery modules with a preset reference value, and diagnose a state of
the plurality of battery modules based on the calculated SOC change amount and the changed
number of battery cells.
The control unit may be configured to, in every cycle, select a target module among
5
the plurality of battery modules, select a target cell among the plurality of battery cells
included in the selected target module, and block a connection between the target cell and the
remaining cells in the selected target module.
The control unit may be configured to select the target module in every cycle such
that the selected target module does not overlap with a target module selected in a former
cycle.
The control unit may be configured to, in every cycle, change the number of target
cells selected in the target module.
The charging and discharging unit may be configured to discharge and charge battery
cells connected to each other among the plurality of battery cells included in the battery
module.
The control unit may be configured to diagnose the state of the battery module as a
normal state or a warning state according to a range to which the calculated SOC change
amount belongs, among a plurality of reference ranges set based on the number of total
battery cells included in the battery module, and output the diagnosis result.
The control unit may be configured to block the connection between the battery pack
and the battery module whose state is diagnosed as the warning state, re-estimate the SOC of
the battery module disconnected from the battery pack after a predetermined time passes,
compare the re-estimated SOC with the predetermined reference value, and output a
diagnosis code based on the comparison result.
A battery pack according to another aspect of the present disclosure may comprise
the apparatus for diagnosing a state of a battery pack according to according to an aspect of
the present disclosure.
A method for diagnosing a state of a battery pack according to still another aspect of
the present disclosure may comprise: a charging and discharging step of discharging and
6
charging a plurality of battery modules having a plurality of battery cells connected to each
other, in every cycle; a monitoring step of measuring a voltage or current of the completely
charged battery modules; a SOC estimating step of estimating a SOC of each battery module
based on the voltage or current measured in the monitoring step; a SOC change amount
calculating step of calculating a SOC change amount by comparing the estimated SOC of
each battery module with a preset reference value; and a diagnosing step of diagnosing a state
of the battery modules based on the calculated SOC change amount.
The method for diagnosing a state of a battery pack according to still another aspect
of the present disclosure may further comprise, before the charging and discharging step: a
target module selecting step of selecting a target module among the plurality of battery
modules; a target cell selecting step of selecting a target cell among the plurality of battery
cells included in the selected target module; and a connection blocking step of blocking the
connection between the target cell and the remaining cells in the selected target module.
The diagnosing step may include: a battery module state determining step of
determining the state of the battery module as any one of a normal state and a warning state,
based on a range to which the calculated SOC change amount belongs, among a plurality of
reference ranges set based on the number of total battery cells included in the battery module;
a battery module connection blocking step of blocking the connection between the battery
module determined as the warning state and the battery pack, as a result of the determination
in the battery module state determining step; a SOC re-estimating step of re-estimating the
SOC of the battery module disconnected from the battery pack, after a predetermined time
passes from the battery module connection blocking step; and a diagnosis code outputting
step of comparing the re-estimated SOC with a predetermined reference value and outputting
a diagnosis code based on the comparison result.
7
Advantageous Effects
According to the present disclosure, since the SOC of the battery module
corresponding to an induced abnormal situation is estimated and the state of each battery
module is diagnosed based on the estimated SOC, a risk factor that may occur in the battery
module may be diagnosed in advance.
In addition, according to the present disclosure, since the state of each battery
module is diagnosed, there is an advantage in that time and cost may be saved compared to
the case of monitoring each battery cell.
In addition, according to the present disclosure, since various abnormal situations are
induced for each battery module and the state of each battery module according to the
induced abnormal situations may be diagnosed, it is possible to diagnose the state of the
battery module from various aspects.
The effects of the present disclosure are not limited to the above, and other effects
not mentioned herein will be clearly understood by those skilled in the art from the appended
claims.
DESCRIPTION OF DRAWINGS
The accompanying drawings illustrate a preferred embodiment of the present
disclosure and together with the foregoing disclosure, serve to provide further understanding
of the technical features of the present disclosure, and thus, the present disclosure is not
construed as being limited to the drawing.
FIG. 1 is a diagram schematically showing an apparatus for diagnosing a state of a
battery pack according to an embodiment of the present disclosure.
FIGS. 2 to 5 are diagrams schematically showing operation processes of the
apparatus for diagnosing a state of a battery pack according to an embodiment of the present
8
disclosure.
FIG. 6 is a diagram schematically showing a method for diagnosing a state of a
battery pack according to another embodiment of the present disclosure.
FIG. 7 is a diagram schematically showing a method for diagnosing a state of a
battery pack according to still another embodiment of the present disclosure.
FIG. 8 is a diagram schematically showing a diagnosing step, in the method for
diagnosing a state of a battery pack according to still another embodiment of the present
disclosure.
BEST MODE
It should be understood that the terms used in the specification and the appended
claims should not be construed as limited to general and dictionary meanings, but interpreted
based on the meanings and concepts corresponding to technical aspects of the present
disclosure on the basis of the principle that the inventor is allowed to define terms
appropriately for the best explanation.
Therefore, the description proposed herein is just a preferable example for the
purpose of illustrations only, not intended to limit the scope of the disclosure, so it should be
understood that other equivalents and modifications could be made thereto without departing
from the scope of the disclosure.
Additionally, in describing the present disclosure, when it is deemed that a detailed
description of relevant known elements or functions renders the key subject matter of the
present disclosure ambiguous, the detailed description is omitted herein.
The terms including the ordinal number such as “first”, “second” and the like, may
be used to distinguish one element from another among various elements, but not intended to
limit the elements by the terms.
9
Throughout the specification, when a portion is referred to as “comprising” or
“including” any element, it means that the portion may include other elements further,
without excluding other elements, unless specifically stated otherwise.
Furthermore, the term “control unit” described in the specification refers to a unit
that processes at least one function or operation, and may be implemented by hardware,
software, or a combination of hardware and software.
In addition, throughout the specification, when a portion is referred to as being
“connected” to another portion, it is not limited to the case that they are “directly connected”,
but it also includes the case where they are “indirectly connected” with another element being
interposed between them.
Hereinafter, a preferred embodiment of the present disclosure will be described in
detail with reference to the accompanying drawings.
FIG. 1 is a diagram schematically showing an apparatus 10 for diagnosing a state of a
battery pack according to an embodiment of the present disclosure.
Here, a battery pack 1 includes a plurality of battery modules and the apparatus 10
for diagnosing a state of a battery pack. Hereinafter, for convenience of description, with
reference to the embodiment shown in FIG. 1, it will be described that four battery modules
BM1, BM2, BM3 and BM4 are included in the battery pack 1.
In addition, the battery module may be a battery bank including one or a plurality of
battery cells. If the battery module includes a plurality of battery cells, the plurality of
battery cells may be connected in series and/or in parallel inside the battery module.
Preferably, each battery module may include a plurality of battery cells connected in parallel
with each other.
Referring to FIG. 1, the apparatus 10 for diagnosing a state of a battery pack
10
according to an embodiment of the present disclosure may include a charging and
discharging unit 100, a monitoring unit 200, and a control unit 300.
The charging and discharging unit 100 may be configured to discharge and charge
the plurality of battery modules BM1, BM2, BM3 and BM4 in a plurality of cycles.
Specifically, the charging and discharging cycle by the charging and discharging unit 100
may be performed at least once, particularly a plurality of times. Here, the charging and
discharging cycle may refer to one process in which the battery module is discharged to a
predetermined lower limit of SOC and then charged to a predetermined upper limit of SOC.
That is, one cycle may mean a process in which the battery module is discharged to the lower
limit of SOC and then charged again to the upper limit of SOC.
Alternatively, the charging and discharging cycle may refer to one process in which
the battery module is charged to a predetermined upper limit of SOC and then discharged to a
predetermined lower limit of SOC. That is, one cycle may mean a process in which the
battery module is charged to the upper limit of SOC and then discharged to the lower limit of
SOC.
Meanwhile, each of the battery modules BM1, BM2, BM3 and BM4 may include a
plurality of battery cells connected to each other. In addition, the plurality of battery
modules BM1, BM2, BM3 and BM4 may be electrically connected to each other. For
example, the plurality of battery modules BM1, BM2, BM3 and BM4 may be connected in
series to each other as shown in the figure. The charging and discharging unit 100 may be
configured to charge and discharge the plurality of battery modules BM1, BM2, BM3 and
BM4 electrically connected as described above as a whole.
For example, one end of the charging and discharging unit 100 may be connected to
a positive electrode terminal (P+) of the battery pack 1, and the other end thereof may be
connected to a negative electrode terminal (P-) of the battery pack 1. Thus, the charging and
11
discharging unit 100 may charge or discharge the plurality of battery modules BM1, BM2,
BM3 and BM4 by a control command of the control unit 300.
The monitoring unit 200 may be configured to measure voltage and/or current of the
plurality of battery modules BM1, BM2, BM3 and BM4, which are completely charged, in
every cycle.
For example, the monitoring unit 200 may be configured to measure the voltage of
each battery module through a plurality of sensing lines SL1, SL2, SL3, SL4 and SL5.
As another example, the monitoring unit 200 may be configured to measure a current
applied to each of the plurality of battery modules BM1, BM2, BM3 and BM4 or a current
output from each of the plurality of battery modules BM1, BM2, BM3 and BM4. In this
case, although not shown in the figure, the monitoring unit 200 may measure the voltage at
both ends of a shunt resistor connected in series with the plurality of battery modules BM1,
BM2, BM3 and BM4. In addition, the monitoring unit 200 may measure a current applied
to the plurality of battery modules BM1, BM2, BM3 and BM4 or a current output from the
plurality of battery modules BM1, BM2, BM3 and BM4 based on the measured potential
difference between both ends of the shunt resistor.
For example, as in the embodiment shown in FIG. 1, the monitoring unit 200 is
connected to the plurality of sensing lines SL1, SL2, SL3, SL4 and SL5, and the plurality of
sensing lines SL1, SL2, SL3, SL4 and SL5 may be connected to the positive electrode
terminals or the negative electrode terminals of the plurality of corresponding battery
modules BM1, BM2, BM3 and BM4.
Specifically, the monitoring unit 200 may measure the voltage of the first battery
module BM1 through the first sensing line SL1 and the second sensing line SL2. In
addition, the monitoring unit 200 may measure the voltage of the second battery module
BM2 through the second sensing line SL2 and the third sensing line SL3. In addition, the
12
monitoring unit 200 may measure the voltage of the third battery module BM3 through the
third sensing line SL3 and the fourth sensing line SL4. Also, the monitoring unit 200 may
measure the voltage of the fourth battery module BM4 through the fourth sensing line SL4
and the fifth sensing line SL5.
Meanwhile, the monitoring unit 200 may also measure not only the voltage of each
of the plurality of battery modules BM1, BM2, BM3 and BM4 but also the voltage of the
plurality of battery modules BM1, BM2, BM3 and BM4 connected to each other, through the
plurality of sensing lines SL1, SL2, SL3, SL4 and SL5.
For example, the monitoring unit 200 may measure the voltage of the first battery
module BM1 and the second battery module BM2 through the first sensing line SL1 and the
third sensing line SL3. That is, through two sensing lines selected from the plurality of
sensing lines SL1, SL2, SL3, SL4 and SL5, the monitoring unit 200 may measure not only
the voltage of each battery module BM1, BM2, BM3, BM4 but also the voltage of two or
more battery modules.
The control unit 300 may be configured to change the number of battery cells
connected to each other and included in the plurality of battery modules in every cycle.
For example, the control unit 300 may select one battery module in every cycle and
change the number of battery cells included in the selected battery module and connected to
each other. Alternatively, the control unit 300 may select a plurality of battery modules in
every cycle and change the number of battery cells included in the plurality of selected
battery modules.
The control unit 300 may receive measurement values for the voltage and/or current
of the plurality of battery modules BM1, BM2, BM3 and BM4 measured by the monitoring
unit 200.
Preferably, the charging and discharging unit 100, the monitoring unit 200 and the
13
control unit 300 may be connected in a wireless and/or wired manner. That is, the control
unit 300 may operate the charging and discharging unit 100 and the monitoring unit 200 by
controlling the charging and discharging unit 100 and the monitoring unit 200, and may
receive the measurement value from the monitoring unit 200.
In addition, the control unit 300 may estimate a state of charge (SOC) of each of the
plurality of battery modules BM1, BM2, BM3 and BM4 based on the received measurement
value.
For example, the control unit 300 may receive a voltage value for the voltage of each
of the plurality of battery modules BM1, BM2, BM3 and BM4 measured by the monitoring
unit 200 and estimate a SOC of each of the plurality of battery modules BM1, BM2, BM3
and BM4 based on the received voltage value. In this case, the control unit 300 may
estimate the SOC of the battery module using a look-up table in which the voltage value and
the SOC are mapped. Here, the look-up table may be stored in a memory of the control unit
300 or in a separate storage unit (not shown). In addition, the control unit 300 may estimate
the SOC of each of the plurality of battery modules BM1, BM2, BM3 and BM4 using the
look-up table.
As another example, the control unit 300 may estimate the SOC of each of the
plurality of battery modules BM1, BM2, BM3 and BM4 by accumulating the current amount
measured by the monitoring unit 200 during charging or discharging of the plurality of
battery modules BM1, BM2, BM3 and BM4.
In general, since it is impossible to measure an open circuit voltage (OCV) in the
process of charging or discharging a battery module and the estimation of SOC based on
voltage or OCV is affected by temperature, the control unit 300 may be configured to
estimate the SOC based on a current while the battery module is being charged or discharged.
Preferably, the control unit 300 may estimate the SOC of each of and the plurality of
14
battery modules BM1, BM2, BM3 and BM4 by accumulating the current amount measured
by the monitoring unit 200 during charging or discharging of the plurality of battery modules
BM1, BM2, BM3 and BM4.
In addition, the control unit 300 may calculate an SOC change amount by comparing
the SOC estimated for each of the battery modules with a preset reference value.
Here, the preset reference value may be set as an SOC estimated when the battery
module in an initial state is fully charged. For example, the preset reference value may be
an SOC estimated when all battery cells included in the battery module in an initial state are
in a normal state and all battery cells are in a fully charged state. Therefore, the preset
reference value may set to 100% and used as a reference value that becomes a comparison
criterion for the SOC of the battery module estimated later.
The control unit 300 may calculate the SOC change amount by calculating a
difference between the preset reference value and the SOC estimated for each of the battery
modules. For example, in the embodiment shown in FIG. 1, assuming that the SOC of the
first battery module BM1 is estimated to be 100%, the control unit 300 may calculate the
difference between the SOC (100%) of the first battery module BM1 and the preset reference
value (100%). In this case, the control unit 300 may calculate 0% as the SOC change
amount for the first battery module BM1.
In addition, the control unit 300 may be configured to diagnose a state of the battery
module based on the calculated SOC change amount and the changed number of battery cells.
For example, in the embodiment shown in FIG. 1, the control unit 300 may calculate
the SOC change amount of each of the first battery module BM1, the second battery module
BM2, the third battery module BM3 and the fourth battery module BM4, and diagnose the
state of each of the first battery module BM1, second battery module BM2, third battery
module BM3, and fourth battery module BM4 by comparing the calculated SOC change
15
amount with a reference range.
Here, the reference range may be an aggregate of a plurality of regions. In addition,
in each of the plurality of regions, an index or a reference for the expected number of battery
cells may be set. That is, based on the result of comparing the calculated SOC change
amount and the reference range, the control unit 300 may obtain a prediction result about the
expected number of battery cells that are expected to be included in each of the plurality of
battery modules BM1, BM2, BM3, and BM4 and connected to each other.
In addition, the control unit 300 may diagnose the state of each of the plurality of
battery modules by comparing the prediction result of the expected number of battery cells
with the changed number of battery cells. The process in which the control unit 300
diagnoses the state of the battery module based on the calculated SOC change amount and the
changed number of battery cells will be described later in detail.
That is, the apparatus 10 for diagnosing a state of a battery pack according to an
embodiment of the present disclosure has an advantage of diagnosing the state of the battery
pack 1 including the plurality of battery modules BM1, BM2, BM3 and BM4 by diagnosing
the state of each of the plurality of battery modules BM1, BM2, BM3 and BM4 based on the
SOC change amount for each battery module.
In addition, the apparatus 10 for diagnosing a state of a battery pack according to an
embodiment of the present disclosure has an advantage that the state of the battery module
and the battery pack 1 may be diagnosed more quickly since the state of the battery module
and the battery pack 1 is diagnosed based on the SOC change amount even if the battery
module is not in an idle state or a no-load state.
The control unit 300 may be configured to select a target module among the plurality
of battery modules BM1, BM2, BM3 and BM4 in every charging and discharging cycle.
16
Here, the control unit 300 may select the target module before each charging and discharging
cycle starts or after each charging and discharging cycle ends. Preferably, the control unit
300 may select the target module at a time point before the charging and discharging cycle
starts.
For example, the control unit 300 may select the target module based on
identification numbers assigned to the plurality of battery modules BM1, BM2, BM3 and
BM4. That is, the control unit 300 may select a battery module whose identification
information is set to 1 as a target module in the first cycle, and select a battery module whose
identification information is set to 2 as a target module in the second cycle.
As another example, the control unit 300 may randomly select a target module
among the plurality of battery modules BM1, BM2, BM3 and BM4. In this case, in order to
prevent duplicate selection of battery modules, the control unit 300 may set a flag for the
battery module selected in a former cycle. For example, the control unit 300 may set a flag
for an already selected battery module to 1 and a flag for a battery module not yet selected to
0. The control unit 300 may randomly select a target module from battery modules whose
flag is set to 0.
Hereinafter, for convenience of explanation, it will be described that the control unit
300 selects a battery module having identification information corresponding to the number
of cycles. That is, the control unit 300 may select the first battery module BM1 as a target
module in the first cycle and select the second battery module BM2 as a target module in the
second cycle.
In addition, the control unit 300 may be configured to select a target cell among the
plurality of battery cells included in the selected target module.
The target cell selection method may be similar to the method in which the control
unit 300 selects a target module. That is, the control unit 300 may select a target cell based
17
on an identification number assigned to a battery cell or may select a target cell based on a
flag set to the battery cell.
In addition, the time point when the control unit 300 selects the target cell may be
immediately after the target module is selected. That is, the control unit 300 may select a
target module and select a target cell at a point immediately before the charging and
discharging cycle starts.
For example, if the first battery module BM1 is selected as a target module in the
first cycle, the control unit 300 may select a target cell among the plurality of battery cells
included in the first battery module BM1.
In addition, the control unit 300 may be configured to block a connection between
the target cell and the remaining cells inside the selected target module. This will be
described in detail with reference to FIGS. 2 to 5.
FIGS. 2 to 5 are diagrams schematically showing operation processes of the
apparatus 10 for diagnosing a state of a battery pack according to an embodiment of the
present disclosure.
Specifically, FIG. 2 is a diagram schematically showing the plurality of battery
modules BM1, BM2, BM3 and BM4 at an initial time point, and FIG. 3 is a diagram
schematically showing the plurality of battery modules BM1, BM2, BM3 and BM4 in a first
cycle. FIG. 4 is a diagram schematically showing the plurality of battery modules BM1,
BM2, BM3 and BM4 in a second cycle, and FIG. 5 is a diagram schematically showing the
plurality of battery modules BM1, BM2, BM3 and BM4 in a third cycle.
Hereinafter, for convenience of explanation, it will be described that the battery pack
1 includes four battery modules and each battery module includes four battery cells as shown
in FIG. 2.
First, referring to FIG. 2, the battery pack 1 includes a first battery module BM1, a
18
second battery module BM2, a third battery module BM3 and a fourth battery module BM4,
and each battery module may include four battery cells.
The plurality of battery cells included in each of the plurality of battery modules
BM1, BM2, BM3 and BM4 A may be connected in parallel to each other inside the battery
module. In addition, the plurality of battery modules BM1, BM2, BM3 and BM4 may be
connected to each other in series.
Referring to FIG. 3, the control unit 300 may select the first battery module BM1 as a
target module in the first cycle. As described above, the control unit 300 may select the first
battery module BM1 based on the identification number of the battery module, or may
randomly select the first battery module BM1 based on the flag set in the battery module.
In addition, the control unit 300 may select a first battery cell BC11 as a target cell
among the battery cells included in the first battery module BM1 selected as the target
module in the first cycle. Also, the control unit 300 may block a connection of the first
battery cell BC11 selected as the target cell to the second battery cell BC12, the third battery
cell BC13 and the fourth battery cell BC14. The electrical connection of the target cell may
be blocked using various cell connection control configurations known at the time of filing of
this application, such as on-off control of a switch (not shown). In this case, only three
battery cells may be connected in parallel inside the first battery module BM1, and four
battery cells may be connected in parallel inside the second to fourth battery modules BM4.
In the first cycle, the control unit 300 may control the charging and discharging unit
100 to discharge and charge the battery cells included in the first to fourth battery modules
BM4 and connected to each other. Preferably, the charging and discharging unit 100 may
discharge and then charge again each of the plurality of battery modules BM1, BM2, BM3
and BM4.
In the first cycle, in the process of charging each of the plurality of battery modules
19
BM1, BM2, BM3 and BM4, the monitoring unit 200 may measure the current applied to each
of the plurality of battery modules BM1, BM2, BM3 and BM4, and the control unit 300 may
estimate a SOC of each of the plurality of battery modules BM1, BM2, BM3 and BM4 based
on the measurement value measured by the monitoring unit 200.
For example, it is assumed that the plurality of battery cells included in the plurality
of battery modules BM1, BM2, BM3 and BM4 are all in a normal state and are an initial state
where degradation does not occur. In this case, in the first cycle, the four battery cells
included in the second battery module BM2, the third battery module BM3 and the fourth
battery module BM4 are all connected in parallel, so the SOC of the second battery module
BM2, the third battery module BM3 and the fourth battery module BM4 may be estimated to
be 100%. Meanwhile, in the first cycle, since only three battery cells are connected in
parallel inside the first battery module BM1, the SOC of the first battery module BM1 can
may be reduced as much as the capacity of the first battery cell BC11. For example, in the
first cycle, the SOC of the first battery module BM1 may be estimated to be 75%. Here,
75% may be a value compared to a preset reference value (for example, a SOC of the first
battery module BM1 at an initial time point).
The control unit 300 may compare the estimated SOC of the first battery module
BM1 with a preset reference value.
For example, as in the former embodiment, the SOC of the first battery module BM1
in the first cycle may be estimated to be 75%, and the preset reference value may be set to be
100%. Here, the preset reference value may be set as an SOC value measured after the
battery module is fully charged in an initial state. In addition, the control unit 300 may
calculate a difference between the preset reference value and the SOC of the first battery
module BM1 to obtain a SOC change amount for the first battery module BM1 as 25%. In
addition, the control unit 300 may diagnose the state of the first battery module BM1 based
20
on the calculated SOC change amount (25%) for the first battery module BM1.
Referring to FIG. 4, the control unit 300 may select the second battery module BM2
as the target module in the second cycle.
After the SOC of each of the plurality of battery modules BM1, BM2, BM3 and
BM4 is estimated in the first cycle, the charging and discharging unit 100 may discharge all
of the plurality of battery modules BM1, BM2, BM3 and BM4. In addition, the control unit
300 may select the second battery module BM2 as the target module in the second cycle.
The control unit 300 may select a first battery cell BC21 and a second battery cell BC22 as
target cells among the battery cells included in the selected second battery module BM2.
The control unit 300 may block the connection of the first battery cell BC21 and the second
battery cell BC22 selected as the target cells in the second cycle to the third battery cell BC23
and the fourth battery cell BC24. In this case, in the second cycle, only three battery cells
may be connected in parallel inside the first battery module BM1, only two battery cells may
be connected in parallel inside the second battery module BM2, and four battery cells may be
connected in parallel inside the third battery module BM3 and the fourth battery module BM4.
After that, the charging and discharging unit 100 may charge all of the plurality of battery
modules BM1, BM2, BM3 and BM4, and the control unit 300 may estimate the SOC of each
of the plurality of battery modules BM1, BM2, BM3 and BM4.
For example, as in the former embodiment, since the connection of the first battery
cell BC11 of the first battery module BM1 is blocked in the first cycle, the SOC of the first
battery module BM1 may be estimated to be 75%, identical to the first cycle. In addition,
since the connection of the first battery cell BC21 and the second battery cell BC22 of the
second battery module BM2 is blocked in the second cycle, the SOC of the second battery
module BM2 may be estimated to be 50%. Also, the SOC of the third battery module BM3
and the fourth battery module BM4 may be estimated to be 100%.
21
The control unit 300 may compare the estimated SOC of the second battery module
BM2 with a preset reference value. For example, as in the former embodiment, the SOC of
the second battery module BM2 in the second cycle may be estimated to be 50%, and the
preset reference value may be set to be 100%. The control unit 300 may calculate a
difference between the preset reference value and the SOC of the second battery module
BM2 to obtain the SOC change amount for the second battery module BM2 as 50%. In
addition, the control unit 300 may diagnose the state of the second battery module BM2
based on the calculated SOC change amount (50%) for the second battery module BM2.
Referring to FIG. 5, the control unit 300 may select the third battery module BM3 as
a target module in the third cycle.
After the SOC of each of the plurality of battery modules BM1, BM2, BM3 and
BM4 is estimated in the second cycle, the charging and discharging unit 100 may discharge
all of the plurality of battery modules BM1, BM2, BM3 and BM4. In addition, the control
unit 300 may select the third battery module BM3 as the target module in the third cycle.
The control unit 300 may select a first battery cell BC31, a second battery cell BC32 and a
third battery cell BC33 as target cells among the battery cells included in the selected third
battery module BM3. The control unit 300 may block the connection of the first battery cell
BC31, the second battery cell BC32 and the third battery cell BC33 selected as target cells in
the third cycle to the fourth battery cell BC34. In this case, in the third cycle, only three
battery cells may be connected in parallel inside the first battery module BM1, only two
battery cells may be connected in parallel inside the second battery module BM2, and only
one battery cell may be connected inside the third battery module BM3, and four battery cells
may be connected in parallel inside the fourth battery module BM4. After that, the charging
and discharging unit 100 may charge all of the plurality of battery modules BM1, BM2, BM3
and BM4, and the control unit 300 may estimate the SOC of each of the plurality of battery
22
modules BM1, BM2, BM3 and BM4.
For example, as in the former embodiment, since the connection of the first battery
cell BC11 of the first battery module BM1 is blocked in the first cycle, the SOC of the first
battery module BM1 may be estimated to be 75%, identical to the first cycle. In addition,
since the connection of the first battery cell BC21 and the second battery cell BC22 of the
second battery module BM2 is blocked in the second cycle, the SOC of the second battery
module BM2 may be estimated to be 50%. Also, since the connection of the first battery
cell BC31, the second battery cell BC32 and the third battery cell BC33 of the third battery
module BM3 is blocked in the third cycle, the SOC of the third battery module BM3 may be
estimated to be 25%. In addition, the SOC of the fourth battery module BM4 may be
estimated to be 100%.
The control unit 300 may compare the estimated SOC of the third battery module
BM3 with a preset reference value. For example, as in the former embodiment, in the third
cycle, the SOC of the third battery module BM3 may be estimated to be 25%, and the preset
reference value may be set to be 100%. The control unit 300 may calculate a difference
between the preset reference value and the SOC of the third battery module BM3 to obtain
the SOC change amount for the third battery module BM3 as 75%. In addition, the control
unit 300 may diagnose the state of the third battery module BM3 based on the calculated
SOC change amount (75%) for the third battery module BM3.
As described above, the apparatus 10 for diagnosing a state of a battery pack
according to an embodiment of the present disclosure may induce an abnormal situation in
the battery module by forcibly blocking the connection of the plurality of battery cells
included in the battery module. In addition, since the apparatus 10 for diagnosing a state of
a battery pack diagnoses the state of the battery module and the battery pack 1 based on the
induced abnormal situation, the battery module and the battery pack 1 may diagnose whether
23
the state is a faulty state. Accordingly, there is an advantage in that the performance
degradation of the battery module may be prevented in advance and problems such as
overcharge or overdischarge of the battery cells may be prevented in advance.
Meanwhile, referring to the embodiments shown in FIGS. 2 and 5, the control unit
300 may block the connection of some of the battery cells included in the plurality of battery
modules BM1, BM2, BM3 and BM4, while omitting the embodiments shown in FIGS. 3 and
4.
That is, the embodiment shown in FIG. 5 may be the state of the battery module in
the first cycle. In this case, in the first cycle, the first battery cell BC11 may be blocked in
the first battery module BM1, the first battery cell BC21 and the second battery cell BC22
may be blocked in the second battery module BM2, and the first battery cell BC31, the
second battery cell BC32 and the third battery cell BC33 may be blocked in the third battery
module BM3.
The control unit 300 may diagnose the state of each of the first battery module BM1,
the second battery module BM2, the third battery module BM3 and the fourth battery module
BM4 based on the SOC of each of the first battery module BM1, the second battery module
BM2, the third battery module BM3 and the fourth battery module BM4.
As described above, the apparatus 10 for diagnosing a state of a battery pack
according to an embodiment of the present disclosure may accurately diagnose the state of
the battery pack 1 while changing the target module in every cycle. In addition, the
apparatus 10 for diagnosing a state of a battery pack may quickly diagnose the state of the
battery pack 1 by selecting a plurality of target modules at once and blocking the connection
of some battery cells included in the target modules.
24
Here, the control unit 300 may optionally include a processor, an application-specific
integrated circuit (ASIC), another chipset, a logic circuit, a register, a communication modem,
and a data processing device, and the like, known in the art to execute various control logics
disclosed below. In addition, when the control logic is implemented in software, the control
unit 103 may be implemented as a set of program modules. At this time, the program
module may be stored in a memory and executed by the processor. The memory may be
provided in or out of the processor, and may be connected to the processor by various wellknown means. In addition, the memory refers to a device in which information is stored
regardless of the type of device, and does not refer to a specific memory device.
The control unit 300 may be a battery management system (BMS) that may be
electrically coupled with a secondary battery, or a control element included in the battery
management system. The battery management system may refer to a system called BMS in
the technical field to which this application belongs, but any system that performs at least one
function described in this specification in a functional point of view may be included in the
category of the battery management system.
The control unit 300 may be configured to select a target module selected in every
cycle so as not to overlap with a target module selected in a former cycle.
That is, the control unit 300 may not repeatedly select the same target module
repeatedly in different cycles in order to quickly diagnose the state of the battery module.
For example, referring to FIGS. 3 to 5, the first battery module BM1 selected as the
target module in the first cycle may not be selected as a target module in the second cycle and
the third cycle. To this end, as described above, the control unit 300 may select a target
module in every cycle by using the identification number of the battery module or the flag set
in the battery module.
25
The apparatus 10 for diagnosing a state of a battery pack according to an
embodiment of the present disclosure may induce various abnormal situations for all battery
modules by preventing duplicate selection of a target module. Therefore, based on the
abnormal situations induced for each of the plurality of battery modules, the state of battery
pack 1 may be quickly diagnosed in various aspects.
The control unit 300 may be configured to change the number of target cells selected
in the target module in every cycle. For example, the control unit 300 may be configured to
increase or decrease the number of target cells selected in the target module in every cycle.
Hereinafter, for convenience of explanation, a case where the number of target cells selected
by the control unit 300 is increased one by one each time the cycle increases will be
described.
Referring to FIGS. 3 to 5, the control unit 300 may select one target cell in the first
cycle, two target cells in the second cycle, and three target cells in the third cycle. The
maximum number of selected target cells may be smaller than the number of battery cells
included in each of the plurality of battery modules BM1, BM2, BM3 and BM4. Preferably,
the maximum number of selected target cells may be smaller than the number of battery cells
included in each of the plurality of battery modules BM1, BM2, BM3 and BM4 by one.
For example, as in the embodiment shown in FIG. 5, in the third cycle, the
connection of the first battery cell BC11 may be blocked in the first battery module BM1, the
connection of the first battery cell BC21 and the second battery cell BC22 may be blocked in
the second battery module BM2, and the connection of the first battery cell BC31, the second
battery cell BC32 and the third battery cell BC33 may be blocked in the third battery module
BM3.
In general, when a plurality of battery cells having different internal capacities are
26
connected in series, the total internal capacity of the battery modules connected in series may
be adapted to the battery cell having the smallest internal capacity. It is assumed that the
internal capacity of a battery cell A is 3500 [mAh], the internal capacity of a battery cell B is
3600 [mAh], and the internal capacity of a battery cell C is 3600 [mAh]. At this time, if the
battery cell A, the battery cell B and the battery cell C are connected in series, the internal
capacity of the battery module connected in series may be 3500 [mAh]. That is, if a
plurality of battery cells having different internal capacities are connected in series and used,
the capacity of each battery cell may not be used at maximum. Thus, in order to prevent this
capacitive damage, battery cells manufactured at the same time through the same production
line may be used as the battery cells generally included in the battery module and the battery
pack 1.
Therefore, since the number of battery cells whose connection is blocked for each
battery module is changed, the apparatus 10 for diagnosing a state of a battery pack according
to an embodiment of the present disclosure may quickly obtain the state diagnosis result of
the battery module for various induced abnormal situations.
The charging and discharging unit 100 may be configured to discharge and charge
battery cells connected to each other among the plurality of battery cells included in the
battery module.
For example, referring to the embodiments shown in FIGS. 2 to 5, the connection of
some battery cells among the plurality of battery cells included in each battery module may
be blocked as the cycle progresses. Specifically, referring to the embodiment shown in FIG.
3, in the first cycle, the connection of the first battery cell BC11 may be blocked among the
first battery cell BC11, the second battery cell BC12, the third battery cell BC13 and the
fourth battery cell BC14 included in the first battery module BM1. Accordingly, the
27
charging and discharging unit 100 may be configured to discharge and charge only the
battery cells BC12, BC13 and BC14 connected to each other among the plurality of battery
cells BC11, BC12, BC13 and BC14 included in the first battery module BM1.
The apparatus 10 for diagnosing a state of a battery pack according to an
embodiment of the present disclosure has an advantage of shortening the charging and
discharging time by charging and discharging battery cells connected to each other.
The control unit 300 may diagnose the state of the battery module to a normal state
or a warning state according to a range to which the calculated SOC change amount belongs,
among a plurality of reference ranges set based on the number of total battery cells included
in the battery module.
Here, the plurality of reference ranges may be a plurality of ranges set according to
the number of battery cells included in the battery module. For example, if four battery cells
are included in the battery module, the plurality of reference ranges may include four
reference ranges. For example, referring to the embodiment shown in FIG. 2, the plurality
of reference ranges may include a 0th reference range, a first reference range, a second
reference range, a third reference range, and a fourth reference range.
The control unit 300 may predict the number of battery cells connected to each other
within the battery module according to the range to which the calculated SOC change amount
of the battery module belongs, among the plurality of reference ranges. That is, an index or
a reference may be set for each of the plurality of reference ranges, and a predicted number of
disconnected battery cells may be set in the index or reference.
For example, if the calculated SOC change amount of the battery module belongs to
the 0th reference range, the control unit 300 may predict the number of disconnected battery
cells inside the battery module as 0. If the calculated SOC change amount of the battery
28
module belongs to the first reference range, the control unit 300 may predict the number of
disconnected battery cells inside the battery module as one. If the calculated SOC change
amount of the battery module belongs to the second reference range, the control unit 300 may
predict the number of disconnected battery cells inside the battery module as two. If the
calculated SOC change amount of the battery module belongs to the third reference range, the
control unit 300 may predict the number of disconnected battery cells inside the battery
module as three. If the calculated SOC change amount of the battery module belongs to the
fourth reference range, the control unit 300 may predict the number of disconnected battery
cells inside the battery module as four.
If the number of battery cells included in the battery module is N, the number of
cases in which the connection of the battery cells is blocked may be N+1 in total. For
example, a case in which all battery cells are connected and a case in which 1 to N number of
battery cells are disconnected may be included, and the total number of such cases is N+1.
Accordingly, as in the embodiment shown in FIG. 2, if four battery cells are included
in the battery module, the plurality of reference ranges may include a 0th reference range, a
first reference range, a second reference range, a third reference range, and a fourth reference
range.
In addition, if the number of disconnected battery cells inside the battery module by
the control unit 300 is the same as the prediction result, the control unit 300 may diagnose the
state of the battery module as a normal state. Conversely, if the number of disconnected
battery cells inside the battery module by the control unit 300 is different from the prediction
result, the control unit 300 may diagnose the state of the battery module as a warning state.
For example, in the embodiment shown in FIGS. 3 to 5, the 0th reference range may
be set to 0% or more and less than 5%, and the first reference range may be set to 20% or
more and less than 30%. In addition, the second reference range may be set to 45% or more
29
and less than 55%, and the third reference range may be set to 70% or more and less than
80%. Finally, the fourth reference range may be set to 95% or more and 100% or less.
If the SOC change amount of the first battery module BM1 is calculated as 25%, the
control unit 300 may compare the SOC change amount (25%) of the first battery module
BM1 with the plurality of reference ranges and determine that the SOC change amount (25%)
of the first battery module BM1 belongs to the first reference range. In addition, the control
unit 300 may predict the number of disconnected battery cells inside the first battery module
BM1 as one by referring to the index or reference set in the first reference range. Since the
first battery cell BC11 is the only battery cell that is disconnected inside the first battery
module BM1 by the control unit 300 and the prediction result is also one, the control unit 300
may diagnose the state of the first battery module BM1 as a normal state.
The following description is on the assumption that the SOC change amount of the
first battery module BM1 is calculated as 45%. If the SOC change amount is calculated
higher than a theoretical change amount, this may be the case where there are other battery
cells disconnected due to an external factor in addition to the battery cells disconnected by
the control unit 300. The control unit 300 may compare the SOC change amount (45%) of
the first battery module BM1 with the plurality of reference ranges and determine that the
SOC change amount (45%) of the first battery module BM1 belongs to the second reference
range. In addition, the control unit 300 may predict the number of disconnected battery
cells inside the first battery module BM1 as two by referring to the index or reference set in
the second reference range. Since only the first battery cell BC11 is disconnected inside the
first battery module BM1 by the control unit 300 but the prediction result is two, the control
unit 300 may diagnose the state of the first battery module BM1 as a warning state.
In addition, as in the former embodiment, depending on the number of battery cells
included in the battery module, a region not belonging to any reference range may exist
30
among the plurality of reference ranges. For example, when the first reference range is 20%
or more and less than 30% and the second reference range is 45% or more and less than 55%,
a region of 30% or more and less than 45% may not belong to any reference range. The
control unit 300 may diagnose the state of the battery module as a warning state even when
the SOC change amount of the battery module does not belong to any reference range.
In addition, the control unit 300 may be configured to output a diagnosis result.
For example, the apparatus 10 for diagnosing a state of a battery pack according to an
embodiment of the present disclosure may further include a display unit to output a diagnosis
result to the user. As another example, the apparatus 10 for diagnosing a state of a battery
pack according to an embodiment of the present disclosure may further include a
communication unit connected to an external network or a communication network to
transmit a diagnosis result to the outside. In this case, the user may check the diagnosis
result for the battery cell by receiving the diagnosis result through a user terminal such as a
mobile phone.
That is, the apparatus 10 for diagnosing a state of a battery pack according to an
embodiment of the present disclosure has an advantage of diagnosing the state of the battery
module early by comparing the number of battery cells disconnected by the control unit 300
with the prediction result of the number of battery cells actually disconnected. In addition,
the apparatus 10 for diagnosing a state of a battery pack has an advantage of inducing various
abnormal situations by changing the number of disconnected battery cells in each battery
module and diagnosing the state of the battery module according to the induced abnormal
situation.
Meanwhile, the apparatus 10 for diagnosing a state of a battery pack according to an
embodiment of the present disclosure may further include a storage unit for storing the
31
diagnosis result. The storage unit may store the diagnosis result and provide comprehensive
diagnosis details for the battery pack 1 to the user. Also, the control unit 300 may calculate
the number of warning state diagnosis in which the state of the battery module stored in the
storage unit is diagnosed as a warning state, before outputting the diagnosis result for the
battery module through the display unit or the communication unit. In addition, the control
unit 300 may be configured to output the latest diagnosis result for the battery module when
the calculated number of warning state diagnosis is greater than or equal to a predetermined
threshold. Here, the predetermined threshold may be basically set by the apparatus 10 for
diagnosing a state of a battery pack, or may be changed by the user.
For example, the control unit 300 may be configured to output the diagnosis result
for the first battery module BM1 stored in the storage unit if the number of warning state
diagnosis for the first battery module BM1 is three or more.
The control unit 300 may block the connection between the battery pack 1 and the
battery module whose state is diagnosed as a warning state.
Here, the battery module diagnosed as a warning state may be a battery module in
which the number of battery cells disconnected by the control unit 300 is different from the
prediction result. For example, if the state of the battery module is diagnosed as a warning
state, the prediction result for predicting the number of battery cells disconnected based on
the result of comparing the SOC change amount of the battery module with the plurality of
reference ranges is two, but the number of battery cells disconnected by the control unit 300
may be one.
The control unit 300 may block the connection between the battery module
diagnosed as a warning state and the battery pack 1, so as to immediately prevent a battery
module other than the normal state maintains the connection with the battery pack 1.
32
In addition, the control unit 300 may connect the battery module that is disconnected
from the battery pack 1 to a preliminary discharge line (not shown). Here, the preliminary
discharge line is a line for discharging the battery module disconnected from the battery pack
1, and may include a discharge contactor and a discharge resistor. Preferably, after the
connection between the battery module and the battery pack 1 is blocked, the control unit 300
may connect the battery module and the preliminary discharge line after a predetermined time
passes before the battery module comes into an idle state or a no-load state.
In addition, the control unit 300 may re-estimate the SOC of the battery module
disconnected from the battery pack 1 after a predetermined time passes.
Here, the predetermined time refers to a point in time when an open circuit voltage
(OCV) of the battery module disconnected from the battery pack 1 is measured as an idle
state or a no-load state.
Preferably, the monitoring unit 200 may measure the OCV when the battery module
is in an idle state or a no-load state. That is, since the battery module disconnected from the
battery pack 1 may be connected to the preliminary discharge line by the control unit 300, the
monitoring unit 200 may measure the OCV of the battery module disconnected from the
battery pack 1.
In addition, the control unit 300 may estimate the SOC of the battery module based
on the OCV measured by the monitoring unit 200. Since OCV and SOC have a one-to-one
correspondence, the control unit 300 may estimate the SOC of the battery module using a
look-up table for OCV and SOC. In this case, the look-up table for OCV and SOC may be
stored in a memory of the control unit 300 or in the storage unit.
The control unit 300 may re-calculate the SOC change amount by comparing the reestimated SOC with the preset reference value again. In addition, like the former
embodiment, the control unit 300 may re-diagnose the state of the battery module, which has
33
been diagnosed as a warning state, based on the result of comparing the re-calculated SOC
change amount with the plurality of reference ranges.
According to this configuration, the state of the battery module may be quickly
diagnosed based on the SOC estimated in the process of charging or discharging the battery
module, and the state of the battery module, which has been diagnosed as a warning state,
may be re-diagnosed based on the OCV. Therefore, since the state of the battery module is
accurately diagnosed through two steps, the accuracy of the state diagnosis of the battery
module may be improved with high reliability.
The control unit 300 may be configured to output a diagnosis code based on the
comparison result. Here, the diagnosis code may be obtained by coding the diagnosis result
described above. Like the former embodiment, the control unit 300 may output the
diagnosis code through a display unit or a communication unit.
The SOC estimated during charging or discharging of the battery module may be
inaccurate compared to the SOC estimated based on the OCV. Therefore, the apparatus 10
for diagnosing a state of a battery pack according to an embodiment of the present disclosure
will improve the reliability and accuracy of the diagnosis result by re-diagnosing the state
based on OCV only for the battery module diagnosed as a warning state.
The battery pack 1 according to an embodiment of the present disclosure may
include the apparatus 10 for diagnosing a state of a battery pack according to the present
disclosure as described above. For example, as shown in FIG. 1, the battery pack 1 may
include the plurality of battery modules BM1, BM2, BM3 and BM4 and the apparatus 10 for
diagnosing a state of a battery pack. In addition, the battery pack 1 according to the present
disclosure may further include electronic equipment (such as a BMS, a relay, a fuse, and the
like) and a pack case, in addition to the apparatus 10 for diagnosing a state of a battery pack.
34
Hereinafter, a method for diagnosing a state of a battery pack 1 according to another
embodiment of the present disclosure will be described with reference to the drawings.
FIG. 6 is a diagram schematically showing a method for diagnosing a state of a
battery pack 1 according to another embodiment of the present disclosure. The method for
diagnosing a state of a battery pack 1 according to another embodiment of the present
disclosure may be performed by the apparatus 10 for diagnosing a state of a battery pack
according to an embodiment of the present disclosure.
Referring to FIG. 6, the method for diagnosing the state of battery pack 1 according
to another embodiment of the present disclosure may include a charging and discharging step
(S100), a monitoring step (S200), a SOC estimating step (S300), a comparing step (S400) and
a diagnosing step (S500).
The charging and discharging step (S100) is a step of discharging and charging the
plurality of battery modules BM1, BM2, BM3 and BM4 having a plurality of battery cells
connected to each other in every cycle, and may be performed by the charging and
discharging unit 100.
The charging and discharging unit 100 may discharge and charge the plurality of
battery modules BM1, BM2, BM3 and BM4 in every cycle. In this case, the charging and
discharging unit 100 may discharge and charge only a battery cell connected to the battery
module among the plurality of battery cells included in the battery module.
The monitoring step (S200) is a step of measuring a voltage or current of the battery
module which is completely charged, and may be performed by the monitoring unit 200.
The SOC estimating step (S300) is a step of estimating the SOC of each of the
battery modules based on the voltage or current measured in the monitoring step (S200), and
may be performed by the control unit 300.
35
The control unit 300 may estimate the SOC of the battery module based on the lookup table for voltage and SOC and may also estimate the SOC of the battery module by
integrating the amount of current flowing during charging or discharging of the battery
module.
The SOC change amount calculating step is a step of calculating an SOC change
amount obtained by comparing the estimated SOC of each of the battery modules with the
preset reference value, and may be performed by the control unit 300.
The control unit 300 may compare the estimated SOC of each battery module with
the preset reference value.
For example, the preset reference value may be set to 100%. In the embodiment
shown in FIG. 3, assuming that the SOC of the first battery module BM1 is estimated to be
75%, the control unit 300 may calculate a difference between the preset reference value and
the estimated SOC of the first battery module BM1 to calculate the SOC change amount of
the first battery module BM1 as 25%.
The diagnosing step (S500) is a step of diagnosing the state of the battery module
based on the calculation result of the SOC change amount, and may be performed by the
control unit 300.
The control unit 300 may diagnose the state of the battery module as a normal state
or a warning state according to a range to which the calculated SOC change amount belongs,
among the plurality of reference ranges set based on the number of total battery cells included
in the battery module.
For example, as in the former embodiment, referring to the embodiment shown in
FIGS. 3 to 5, when four battery cells are included in the battery module, the plurality of
reference ranges may include first to third reference ranges. In this case, the first reference
range may be set to 20% or more and less than 30%, and the second reference range may be
36
set to 45% or more and less than 55%. The third reference range may be set to 70% or more
and less than 80%.
If the SOC change amount of the first battery module BM1 is calculated as 25%, the
control unit 300 may compare the SOC change amount (25%) of the first battery module
BM1 with the plurality of reference ranges and determine that the SOC change amount (25%)
of the first battery module BM1 belongs to the first reference range. In addition, the control
unit 300 may actually predict the number of disconnected battery cells inside the first battery
module BM1 as one. Since the first battery cell BC11 is the only battery cell that is
disconnected inside the first battery module BM1 by the control unit 300 and the prediction
result is also one, the control unit 300 may diagnose the state of the first battery module BM1
as a normal state.
That is, the method for diagnosing a state of a battery pack 1 according to an
embodiment of the present disclosure has an advantage of diagnosing the state of the battery
pack 1 including the battery module by diagnosing the state of each battery module based on
the SOC change amount of each battery module.
FIG. 7 is a diagram schematically showing a method for diagnosing a state of a
battery pack 1 according to still another embodiment of the present disclosure.
Referring to FIG. 7, before the charging and discharging step (S100), a target module
selecting step (S10), a target cell selecting step (S20), and a connection blocking step (S30)
may be further included.
The target module selecting step (S10) is a step of selecting a target module among
the plurality of battery modules BM1, BM2, BM3 and BM4, and may be performed by the
control unit 300.
In every cycle, the control unit 300 may select a target module based on an
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identification number assigned to the plurality of battery modules BM1, BM2, BM3 and
BM4, or select a target module randomly based on a flag set in the plurality of battery
modules BM1, BM2, BM3 and BM4. That is, the control unit 300 may select a battery
module as a target module in every cycle not to be overlapped.
For example, referring to FIGS. 3 to 5, the control unit 300 may select the first
battery module BM1 as a target module in the first cycle, select the second battery module
BM2 as a target module in the second cycle, and select the third battery module BM3 as a
target module in the third cycle.
The target cell selecting step (S20) is a step of selecting a target cell among the
plurality of battery cells included in the selected target module, and may be performed by the
control unit 300.
The connection of the battery cell selected as a target cell may be blocked from the
remaining battery cells included in the corresponding battery module. The control unit 300
may select a target cell in a similar way to the method of selecting a target module. For
example, the control unit 300 may select a target cell based on an identification number
assigned to the battery cell, or randomly select a target cell based on a flag set in the battery
cell.
Also, the number of target cells to be selected may be changed in every cycle.
Preferably, the number of target cells to be selected may be increased each time the cycle
proceeds.
For example, referring to FIGS. 3 to 5, one target cell BC11 may be selected in the
first cycle, two target cells BC21 and BC22 may be selected in the second cycle, and three
target cells BC31, BC32 and BC33 may be selected in the third cycle.
The connection blocking step (S30) is a step of blocking the connection between the
target cell and the remaining cells in the selected target module, and may be performed by the
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control unit 300.
In addition, after the diagnosing step (S500), a cycle comparing step (S600) may be
performed.
The cycle comparing step (S600) is a step of comparing whether the current cycle is
the same as the preset cycle, and may be performed by the control unit 300. Here, the preset
cycle may be related to the number of state diagnosis repeatedly performed for the battery
pack 1. Preferably, the preset cycle may be set smaller than the number of battery modules
included in the battery pack 1. For example, assuming that four battery modules are
connected in series in the battery pack 1, the preset cycle may be set to 3. In each cycle,
since the target module is selected as a battery module not selected in the former cycle, the
preset cycle may be set smaller than the number of battery modules included in the battery
pack 1.
If the current cycle is the same as the preset cycle, the control unit 300 may be
configured to terminate the method for diagnosing a state of the battery pack 1.
The method for diagnosing a state of the battery pack 1 according to another
embodiment of the present disclosure may induce an abnormal situation to constitute the
plurality of battery modules BM1, BM2, BM3 and BM4 so that the number of battery cells
connected to each other is changed, through the target module selecting step (S10), the target
cell selecting step (S20) and the connection blocking step (S30). Therefore, the method for
diagnosing a state of the battery pack 1 has an advantage of diagnosing the state of the battery
module and the battery pack 1 in various aspects by diagnosing the state of each battery
module in an induced abnormal situation.
FIG. 8 is a diagram schematically showing a diagnosing step (S500), in the method
for diagnosing a state of a battery pack 1 according to still another embodiment of the present
39
disclosure.
Referring to FIG. 8, the diagnosing step (S500) may include a battery module state
determining step (S510), a battery module connection blocking step (S520), an SOC reestimating step (S530), and a diagnosis code outputting step (S540). That is, in the
embodiment shown in FIGS. 6 and 7, the battery module state determining step (S510), the
battery module connection blocking step (S520), the SOC re-estimating step (S530) and the
diagnosis code outputting step (S540) may be performed after the comparing step (S400).
The battery module state determining step (S510) is a step of determining the state of
the battery module as any one of a normal state and a warning state based on the range to
which the calculated SOC change amount belongs, among the plurality of reference ranges
set based on the number of total battery cells included in the battery module is, and may be
performed by the control unit 300.
For example, it is assumed that the plurality of reference ranges includes a first
reference range, a second reference range and a third reference range. If the calculated SOC
change amount of the battery module belongs to the first reference range, the control unit 300
may predict the number of disconnected battery cells inside the battery module as one. If
the calculated SOC change amount of the battery module belongs to the second reference
range, the control unit 300 may predict the number of disconnected battery cells inside the
battery module as two. If the calculated SOC change amount of the battery module belongs
to the third reference range, the control unit 300 may predict the number of disconnected
battery cells inside the battery module as three.
In addition, if the number of battery cells disconnected by the control unit 300 is the
same as the prediction result, the state of the corresponding battery module may be
determined as a normal state. Conversely, if the number of battery cells disconnected by the
control unit 300 is different from the prediction result, the state of the corresponding battery
40
module may be determined as a warning state.
For example, as in the former embodiment, referring to the embodiments shown in
FIGS. 3 to 5, if four battery cells are included in the battery module, the plurality of reference
ranges may include first to third reference ranges. In this case, the first reference range may
be set to 20% or more and less than 30%, and the second reference range may be set to 45%
or more and less than 55%. The third reference range may be set to 70% or more and less
than 80%.
If the SOC change amount of the first battery module BM1 is calculated as 25%, the
control unit 300 may compare the SOC change amount (25%) of the first battery module
BM1 with the plurality of reference ranges and determine that the SOC change amount (25%)
of the first battery module BM1 belongs to the first reference range. In addition, the control
unit 300 may actually predict the number of disconnected battery cells inside the first battery
module BM1 as one. Since only the first battery cell BC11 is disconnected inside the first
battery module BM1 by the control unit 300 and the prediction result is also one, the control
unit 300 may determine the state of the first battery module BM1 as a normal state.
The following description is on the assumption that the SOC change amount of the
first battery module BM1 is calculated as 45%. If the SOC change amount is calculated
higher than a theoretical change amount, this may be the case where there are other battery
cells disconnected due to an external factor in addition to the battery cells disconnected by
the control unit 300. The control unit 300 may compare the SOC change amount (45%) of
the first battery module BM1 with the plurality of reference ranges and determine that the
SOC change amount (45%) of the first battery module BM1 belongs to the second reference
range. In addition, the control unit 300 may predict the number of disconnected battery
cells inside the first battery module BM1 as two. Since only the first battery cell BC11 is
disconnected inside the first battery module BM1 by the control unit 300 but the prediction
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result is two, the control unit 300 may diagnose the state of the first battery module BM1 as a
warning state.
The battery module connection blocking step (S520) is a step of blocking the
connection between the battery module determined as a warning state and the battery pack 1
as a result of determination in the battery module state determining step (S510), and may be
performed by the control unit 300.
The control unit 300 may block the connection between the battery module
determined as a warning state and the battery pack 1. That is, the battery module in the
warning state may be continuously connected to the battery pack 1 to prevent charging or
discharging. Therefore, according to this configuration, since the charging and discharging
of the battery module in the warning state is blocked, accidents such as swelling, ignition and
explosion that may occur from the battery module in the warning state may be prevented.
In addition, the control unit 300 may connect the disconnected battery module to the
preliminary discharge line (not shown).
The SOC re-estimating step (S530) is a step of re-estimating the SOC of the battery
module disconnected from the battery pack 1 after a predetermined time passes from the
battery module connection blocking step (S520), and may be performed by the monitoring
unit 200 and the control unit 300.
Here, the point of time when the predetermined time passes is a point of time when
the battery module disconnected from the battery pack 1 comes into an idle state or a no-load
state, and refer to a point of time when OCV can be measured.
After the predetermined time passes, the monitoring unit 200 may measure the OCV
of the battery module disconnected from the battery pack 1. That is, since the battery
module disconnected from the battery pack 1 is connected to the preliminary discharge line,
the OCV may be measured by the monitoring unit 200 even if the battery module is
42
disconnected from the battery pack 1. Preferably, after the battery module and the battery
pack 1 are disconnected, the control unit 300 may connect the battery module and the
preliminary discharge line after a predetermined time passes before the battery module comes
into an idle state or a no-load state. In addition, the monitoring unit 200 may measure the
OCV immediately after the battery module and the preliminary discharge line are connected.
The control unit 300 may re-estimate the SOC of the battery module based on the
OCV measured by the monitoring unit 200.
The diagnosis code outputting step (S540) is a step of comparing the re-estimated
SOC with a predetermined reference value and outputting a diagnosis code based on the
comparison result, and may be performed by the control unit 300.
Preferably, in the diagnosis code outputting step (S540), the comparing step (S400)
may be performed again. That is, the control unit 300 may compare the re-estimated SOC
with the predetermined reference value to calculate an SOC change amount, and may
compare the calculated SOC change amount with the plurality of reference ranges. In
addition, the control unit 300 may diagnose the state of the battery module as a normal state
or a warning state based on the comparison result, and may output a diagnosis code.
The embodiments of the present disclosure described above are not necessarily
implemented by an apparatus and method but may also be implemented through a program
for realizing functions corresponding to the configuration of the present disclosure or a
recording medium on which the program is recorded. Such implementation may be easily
performed by those skilled in the art from the above description of the embodiments.
The present disclosure has been described in detail. However, it should be
understood that the detailed description and specific examples, while indicating preferred
embodiments of the disclosure, are given by way of illustration only, since various changes
43
and modifications within the scope of the disclosure will become apparent to those skilled in
the art from this detailed description.
Additionally, many substitutions, modifications and changes may be made to the
present disclosure described hereinabove by those skilled in the art without departing from
the technical aspects of the present disclosure, and the present disclosure is not limited to the
above-described embodiments and the accompanying drawings, and each embodiment may
be selectively combined in part or in whole to allow various modifications.
(Reference Signs)
1: battery pack
10: apparatus for diagnosing a state of a battery pack
100: charging and discharging unit
200: monitoring unit
300: control unit
BM1 to BM4: first to fourth battery module
BC11 to BC14: first to fourth battery cells included in the first battery module
BC21 to BC24: first to fourth battery cells included in the second battery module
BC31 to BC34: first to fourth battery cells included in the third battery module
BC41 to BC44: first to fourth battery cells included in the fourth battery module

WE CLAIM:
1. An apparatus for diagnosing a state of a battery pack, comprising:
a charging and discharging unit configured to discharge and charge a plurality of
battery modules having a plurality of battery cells connected to each other, in a plurality of
cycles;
a monitoring unit configured to measure a voltage or current of the plurality of
completely charged battery modules, in every cycle; and
a control unit configured to, in every cycle, change the number of battery cells
included in the plurality of battery modules and connected to each other, receive a
measurement value for the voltage or current of the plurality of battery modules measured by
the monitoring unit, estimate a state of charge (SOC) of each of the plurality of battery
modules based on the received measurement value, calculate a SOC change amount by
comparing the estimated SOC of each of the plurality of battery modules with a preset
reference value, and diagnose a state of the plurality of battery modules based on the
calculated SOC change amount and the changed number of battery cells.
2. The apparatus for diagnosing a state of a battery pack according to claim 1,
wherein the control unit is configured to, in every cycle, select a target module
among the plurality of battery modules, select a target cell among the plurality of battery cells
included in the selected target module, and block a connection between the target cell and the
remaining cells in the selected target module.
3. The apparatus for diagnosing a state of a battery pack according to claim 2,
wherein the control unit is configured to select the target module in every cycle such
45
that the selected target module does not overlap with a target module selected in a former
cycle.
4. The apparatus for diagnosing a state of a battery pack according to claim 2,
wherein the control unit is configured to, in every cycle, change the number of target
cells selected in the target module.
5. The apparatus for diagnosing a state of a battery pack according to claim 2,
wherein the charging and discharging unit is configured to discharge and charge
battery cells connected to each other among the plurality of battery cells included in the
battery module.
6. The apparatus for diagnosing a state of a battery pack according to claim 1,
wherein the control unit is configured to diagnose the state of the battery module as a
normal state or a warning state according to a range to which the calculated SOC change
amount belongs, among a plurality of reference ranges set based on the number of total
battery cells included in the battery module, and output the diagnosis result.
7. The apparatus for diagnosing a state of a battery pack according to claim 6,
wherein the control unit is configured to block the connection between the battery
pack and the battery module whose state is diagnosed as the warning state, re-estimate the
SOC of the battery module disconnected from the battery pack after a predetermined time
passes, compare the re-estimated SOC with the predetermined reference value, and output a
diagnosis code based on the comparison result.
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8. A battery pack, comprising the apparatus for diagnosing a state of a battery
pack according to any one of claims 1 to 7.
9. A method for diagnosing a state of a battery pack, comprising:
a charging and discharging step of discharging and charging a plurality of battery
modules having a plurality of battery cells connected to each other, in every cycle;
a monitoring step of measuring a voltage or current of the completely charged battery
modules;
a SOC estimating step of estimating a SOC of each battery module based on the
voltage or current measured in the monitoring step;
a SOC change amount calculating step of calculating a SOC change amount by
comparing the estimated SOC of each battery module with a preset reference value; and
a diagnosing step of diagnosing a state of the battery modules based on the calculated
SOC change amount.
10. The method for diagnosing a state of a battery pack according to claim 9,
before the charging and discharging step, further comprising:
a target module selecting step of selecting a target module among the plurality of
battery modules;
a target cell selecting step of selecting a target cell among the plurality of battery
cells included in the selected target module; and
a connection blocking step of blocking the connection between the target cell and the
remaining cells in the selected target module.
11. The method for diagnosing a state of a battery pack according to claim 9,

wherein the diagnosing step includes:
a battery module state determining step of determining the state of the battery
module as any one of a normal state and a warning state, based on a range to which the
calculated SOC change amount belongs, among a plurality of reference ranges set based on
the number of total battery cells included in the battery module;
a battery module connection blocking step of blocking the connection between the
battery module determined as the warning state and the battery pack, as a result of the
determination in the battery module state determining step;
a SOC re-estimating step of re-estimating the SOC of the battery module
disconnected from the battery pack, after a predetermined time passes from the battery
module connection blocking step; and
a diagnosis code outputting step of comparing the re-estimated SOC with a
predetermined reference value and outputting a diagnosis code based on the comparison
result.