FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
“WIRELESS BATTERY MANAGEMENT SYSTEM AND
BATTERY PACK INCLUDING SAME”
LG CHEM, LTD., of 128, Yeoui-daero, Yeongdeungpo-gu, Seoul 07336, Republic of
Korea
The following specification particularly describes the invention and the manner in which it is
to be performed.
2
TECHNICAL FIELD
The present disclosure relates to a wireless battery management system, and more
particularly, to a wireless battery management system for reducing a residual capacity
deviation between battery modules and a battery pack including the same.
5 The present application claims priority to Korean Patent Application No. 10-2017-
0092151 filed in the Republic of Korea on July 20, 2017, the disclosures of which are
incorporated herein by reference.
BACKGROUND ART
10 Recently, there is dramatically growing demand for portable electronic products
such as laptop computers, video cameras and mobile phones, and with the extensive
development of electric vehicles, accumulators for energy storage, robots and satellites,
many studies are being made on high performance secondary batteries that can be
recharged repeatedly.
15 Currently, commercially available secondary batteries include nickel-cadmium
batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium secondary batteries and
the like, and among them, lithium secondary batteries have little or no memory effect, and
thus they are gaining more attention than nickel-based secondary batteries for their
advantages of free charging and discharging, very low self-discharging and high energy
20 density.
A battery pack applied to electric vehicles generally includes a plurality of battery
modules connected in series and a plurality of battery management systems (BMSs).
Each BMS monitors and controls the state of the battery module that the BMU manages.
3
Recently, to meet the demand for high-capacity high-output battery packs, the number of
battery modules included in a battery pack also increases. To efficiently manage the state
of each battery module included in the battery pack, a single master-multi slave structure is
disclosed. The single master-multi slave structure includes a plurality of slave BMSs
5 installed in each battery module and a master BMS that controls the overall operation of
the plurality of slave BMSs. In this instance, communication between the plurality of
slave BMSs and the master BMS may be performed by a wireless method.
Each of the plurality of slave BMSs transmits a wireless signal to the master BMS
or receives a wireless signal from the master BMS using electrical energy of the battery
10 module in which the slave BMS is coupled.
Meanwhile, due to the environment in which the battery pack operates or the
electrical and chemical properties of the individual battery module, a residual capacity
deviation often occurs between the plurality of battery modules. To reduce the residual
capacity deviation between the plurality of battery modules, balancing control is necessary.
15 However, most of conventional technologies related to balancing have applications
in systems designed for communication between a plurality of slave BMSs and a master
BMS through wired means such as a cable.
DISCLOSURE
20 Technical Problem
The present disclosure is directed to providing a wireless battery management
system for performing module balancing to reduce a residual capacity deviation between
battery modules by transmitting a radio frequency (RF) signal through a non-
4
communication wireless channel using electrical energy of at least one of the battery
modules, and a battery pack including the same.
These and other objects and advantages of the present disclosure will be
understood by the following description and will be apparent from the embodiments of the
5 present disclosure. Further, it will be readily understood that the objects and advantages
of the present disclosure can be realized by the means set forth in the appended claims and
combinations thereof.
Technical Solution
10 Various embodiments of the present disclosure for achieving the above-described
object are as follows.
A wireless battery management system according to an aspect of the present
disclosure includes a master BMS configured to transmit a first radio frequency (RF)
signal including a state detection command through a first wireless channel. The wireless
15 battery management system further includes a plurality of slave BMSs coupled to a
plurality of battery modules in one-to-one correspondence. Each of the plurality of slave
BMSs is configured to detect state information of the battery module to which the
corresponding slave BMS is coupled in response to the first RF signal, and transmit a
second RF signal indicating the state information of the battery module through the first
20 wireless channel. The master BMS is configured to determine a wireless balancing time
for each of the plurality of battery modules based on the second RF signal, and transmit a
third RF signal including a module balancing command indicating the wireless balancing
time to the plurality of slave BMSs through the first wireless channel. Each of the
5
plurality of slave BMSs is configured to transmit a fourth RF signal through a second
wireless channel during the wireless balancing time using electrical energy of the battery
module to which the corresponding slave BMS is coupled according to the module
balancing command included in the third RF signal.
5 The first wireless channel may have a preset first frequency range. In this case,
the second wireless channel may have a preset second frequency range that is separated
from the first frequency range.
The master BMS may calculate a module residual capacity stored in each of the
plurality of battery modules based on the second RF signal, and determine the wireless
10 balancing time for each of the plurality of battery modules based on the module residual
capacity of each of the plurality of battery modules.
The master BMS may set the module residual capacity of one of the plurality of
battery modules as a first target residual capacity, and determine the wireless balancing
time for each of the plurality of battery modules based on a difference between the first
15 target residual capacity and each of the other module residual capacities.
The state information of the battery module may include state information of each
battery cell included in the battery module. The master BMS may calculate a cell residual
capacity of each battery cell included in each of the plurality of battery modules based on
the second RF signal, and determine the wireless balancing time for each of the plurality of
20 battery modules based on the cell residual capacity of each battery cell included in each of
the plurality of battery modules.
The master BMS may determine a smallest cell residual capacity of cell residual
capacities of all battery cells included in the plurality of battery modules as second target
6
residual capacity, and determine the wireless balancing time for each of the plurality of
battery modules further based on a difference between the second target residual capacity
and the minimum cell residual capacity of each of the other battery modules.
The master BMS may determine a wired balancing time for each battery cell
5 included in each of the plurality of battery modules based on a difference between the
minimum cell residual capacity of each of the plurality of battery modules and each of the
other cell residual capacities. In this case, the third RF signal may further include a cell
balancing command indicating the wired balancing time.
Each of the plurality of slave BMSs may include a wired balancing unit
10 electrically connected to two ends of each battery cell included in the battery module to
which the corresponding slave BMS is coupled. Each of the plurality of slave BMSs may
balance the cell residual capacity of each battery cell included in the battery module to
which the corresponding slave BMS is coupled by controlling the wired balancing unit
according to the cell balancing command included in the third RF signal.
15 A battery pack according to another aspect of the present disclosure includes the
wireless battery management system and the plurality of battery modules.
Advantageous Effects
According to at least one of the embodiments of the present disclosure, it is
20 possible to perform module balancing to reduce a residual capacity deviation between
battery modules by transmitting a radio frequency (RF) signal through a noncommunication wireless channel using electrical energy of at least one of the battery
modules.
7
Additionally, according to at least one of the embodiments of the present
disclosure, it is possible to performed module balancing even while state information from
each battery module is being detectd, thereby reducing the time required to finish module
balancing and cell balancing completely.
5 Additionally, according to at least one of the embodiments of the present
disclosure, module balancing is performed first based on the minimum cell residual
capacity of each battery module and then cell balancing is performed, so there is available
time for cell balancing.
The effects of the present disclosure are not limited to the above-mentioned effects,
10 and other effects not mentioned herein will be clearly understood by those skilled in the art
from the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings illustrate a preferred embodiment of the present
15 disclosure, and together with the detailed description of the present disclosure described
below, serve to provide a further understanding of the technical aspects of the present
disclosure, and thus, the present disclosure should not be construed as being limited to the
drawings.
FIG. 1 is a schematic diagram showing configuration of a wireless battery
20 management system according to an embodiment of the present disclosure and a battery
pack including the same.
FIG. 2 is a schematic diagram showing configuration of a slave BMS shown in
FIG. 1.
8
FIG. 3 is a schematic diagram showing configuration of a wired balancing unit
according to an embodiment of the present disclosure.
FIG. 4 is a schematic diagram showing configuration of a master BMS shown in
FIG. 1.
5 FIGS. 5 and 6 are diagrams for reference in describing the operation of balancing a
plurality of battery modules according to a first balancing rule by a wireless battery
management system according to an embodiment of the present disclosure.
FIGS. 7 and 8 are diagrams for reference in describing the operation of balancing a
plurality of battery modules according to a second balancing rule by a wireless battery
10 management system according to an embodiment of the present disclosure.
MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the preferred embodiments of the present disclosure will be described
in detail with reference to the accompanying drawings. Prior to the description, it should
15 be understood that the terms or words used in the specification and the appended claims
should not be construed as being limited to general and dictionary meanings, but
interpreted based on the meanings and concepts corresponding to the technical aspects of
the present disclosure on the basis of the principle that the inventor is allowed to define the
terms appropriately for the best explanation.
20 Therefore, the embodiments described herein and illustrations shown in the
drawings are just a most preferred embodiment of the present disclosure, but not intended
to fully describe the technical aspects of the present disclosure, so it should be understood
that a variety of other equivalents and modifications could be made thereto at the time of
9
filing the application.
Additionally, in describing the present disclosure, when it is deemed that a certain
detailed description of relevant known elements or functions renders the key subject matter
of the present disclosure ambiguous, the detailed description is omitted herein.
5 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.
Unless the context clearly indicates otherwise, it will be understood that the term
"comprises" or "includes" when used in this specification, specifies the presence of stated
10 elements, but does not preclude the presence or addition of one or more other elements.
Additionally, the term as used herein refers to a processing unit of at least
one function or operation, and this may be implemented by hardware or software alone or
in combination.
In addition, throughout the specification, it will be further understood that when an
15 element is referred to as being "connected to" another element, it can be directly connected
to the other element or intervening elements may be present.
It should be noted that the term "BMS" as used herein is a shorted form of Battery
Management System.
FIG. 1 is a schematic diagram showing configuration of a wireless battery
20 management system 30 according to an embodiment of the present disclosure and a battery
pack 10 including the same.
Referring to FIG. 1, the battery pack 10 includes a plurality of battery modules 20
and a wireless battery management system 30. Each battery module 20 may include at
10
least one battery cell (see 21 in FIG. 2). The wireless battery management system 30
includes a plurality of slave BMSs 100 and at least one master BMS 200. The battery
pack 10 may be mounted in an electric vehicle to supply power required for operating an
electric motor of the electric vehicle.
5 Hereinafter, for convenience of description, assume that the battery pack 10
includes three battery modules 20-1~20-3 connected in series, each battery module 20
includes three battery cells 21 connected in series, and the wireless battery management
system 30 includes three slave BMSs 100-1~100-3 and a single master BMS 200.
However, the scope of the present disclosure is not limited thereto. For example, the
10 battery pack 10 may include only two battery modules 20 or four or more battery modules
20. Of course, the wireless battery management system 30 may include two slave BMSs
100 or four or more slave BMSs 100, and may include two or more master BMSs 200.
The plurality of slave BMSs 100-1~100-3 is coupled in one-to-one correspondence
to the plurality of battery modules 20-1~20-3 included in the battery pack 10.
15 Each of the plurality of slave BMSs 100-1~100-3 is electrically connected to one
of the plurality of battery modules 20-1~20-3. Each of the plurality of slave BMSs 100-
1~100-3 detects the overall state (for example, voltage, current, temperature) of the battery
modules 20-1~20-3 electrically connected to the slave BMSs 100-1~100-3, and performs a
variety of control functions (for example, charging, discharging, balancing) to adjust the
20 state of the battery modules 20-1~20-3. Each control function may be performed directly
by the slave BMS 100 based on the state of the battery module 20, or may be performed
according to the command from the master BMS 200.
FIG. 2 is a schematic diagram showing configuration of the slave BMS 100 shown
11
in FIG. 1, and FIG. 3 is a shematic diagram showing configuration of a wired balancing
unit 140 according to an embodiment of the present disclosure.
Referring to FIG. 2, each slave BMS 100 may include a slave memory 110, a slave
communication unit 120, a slave sensing unit 130, a slave power supply unit 150 and a
5 slave control unit 160. Optionally, each slave BMS 100 may further include a wired
balancing unit 140.
The slave memory 110 stores an ID allocated to the slave BMS 100. The ID may
be allocated in the manufacture of the slave BMS 100 including the slave memory 110.
The ID may be used for each slave BMS 100 to perform wireless communication with the
10 master BMS 200. In this instance, the ID allocated to one of the plurality of slave BMSs
100-1~100-3 may be different from the IDs allocated to each of the other slave BMSs.
Each ID may be used for the master BMS 200 to distinguish each slave BMS 100
(e.g. 100-1) from the other slave BMS 100 (e.g. 100-2). Additionally, each ID may
represent which of the plurality of battery modules 20-1~20-3 at which the slave BMS 100
15 with the allocated ID is installed.
The slave memory 110 is not limited to a particular type and includes any known
information storage means capable of recording, deleting, updating and reading data. For
example, the slave memory 110 may be DRAM, SDRAM, flash memory, ROM, EEPROM
and a register. The slave memory 110 may store program codes defining the processes
20 that can be executed by the slave control unit 160.
The slave memory 110 may be physically separated from the slave control unit
160, or may be integrated into a chip with the slave control unit 160.
The slave communication unit 120 includes a slave antenna 121 and a slave
12
communication circuit 122. The slave antenna 121 and the slave communication circuit
122 are operably connected to each other. The slave communication circuit 122
demodulates a wireless signal received by the slave antenna 121. Additionally, the slave
communication circuit 122 may modulate a signal provided from the slave control unit 160
5 and provide it to the slave antenna 121. The slave antenna 121 may transmit a wireless
signal corresponding to the signal modulated by the slave communication circuit 122 to the
other slave BMS or the master BMS 200 simultaneously or selectively.
The slave sensing unit 130 is configured to detect state information of the battery
module 20. For example, the slave sensing unit 130 includes a voltage measurement
10 circuit to detect the voltage of the battery module 20, and optionally, may further include a
current measurement circuit to detect the current of the battery module 20, or a temperature
detection circuit to detect the temperature of the battery module 20. The slave sensing
unit 130 provides the detected state information of the battery module 20 to the slave
control unit 160. The slave sensing unit 130 may include at least one application specific
15 integrated circuit (ASIC) having a voltage detection circuit and a temperature detection
circuit embedded therein.
The wired balancing unit 140 is configured to reduce a residual capacity deviation
between the plurality of battery cells 21 included in each battery module 20. The wired
balancing unit 140 is configured to perform cell balancing.
20 For example, the wired balancing unit 140 discharges the battery cell 21 having
higher residual capacity than the other battery cell 21 to equalize the residual capacity
between the plurality of battery cells 21.
Referring to FIG. 3, the wired balancing unit 140 includes a plurality of balancing
13
resistors Rc and a plurality of balancing switches SW. A series circuit including one
balancing resistor RC and one balancing switch SW is connected between two ends of each
battery cell 21. Accordingly, the number of battery cells 21 per the battery module 20
may be equal to the number of balancing resistors RC and the number of balancing
5 switches SW included in each wired balancing unit 140.
When the voltage or residual capacity of a specific battery cell 21 is higher than
the other battery cell 21, the balancing switch SW connected between two ends of the
specific battery cell 21 is turned on, then electrical energy of the specific battery cell 21 is
consumed by the balancing resistor Rc.
10 Meanwhile, in FIG. 2, Ra is a diagnosis resistor, and is used to detect a failure in
the wired balancing unit 140. The failure in the wired balancing unit 140 may be, for
example, a disconnection or a malfunction of the balancing switch SW. Additionally, in
FIG. 2, Rb and C are a protection resistor and a protection capacitor respectively, and act as
a RC filter. The RC filter is used to filter off noise (for example, a sharp change in
15 current) entering the sensing unit 130.
The slave power supply unit 150 generates at least one preset level of power
source voltage using the power supplied from the battery module 20. The power source
voltage generated by the slave power supply unit 150 may be individually supplied to the
slave memory 110, the slave communication unit 120, the slave sensing unit 130 and/or
20 and the wired balancing unit 140. Additionally, the power source voltage generated by
the slave power supply unit 150 may be supplied to each processor included in the slave
control unit 160. For example, first power source voltage generated by the slave power
supply unit 150 may be used as the operating power of each processor included in the
14
wired balancing unit 140 and the slave control unit 160, and second power source voltage
generated by the slave power supply unit 150 may be used as the operating power of each
of the slave memory 110, the slave communication unit 120 and/or the slave sensing unit
130.
5 The slave power supply unit 150 may perform module balancing of the battery
module 20 together with the slave communication unit 120 according to the command of
the slave control unit 160.
The slave control unit 160 includes at least one processor, and is operably
connected to the slave memory 110, the slave communication unit 120 and the slave power
10 supply unit 150. The slave control unit 160 is configured to manage the overall operation
of the slave BMS 100 including the slave control unit 160.
The slave control unit 160 provides the state information of the battery module 20
detected by the slave sensing unit 130 to the slave communication unit 120. Accordingly,
the slave communication unit 120 transmits a wireless signal indicating the state
15 information of the battery module 20 to the master BMS 200 through the slave antenna 121.
Each processor included in the slave control unit 160 may selectively include a
processor, an application-specific integrated circuit (ASIC), a chipset, a logic circuit, a
register, a communication modem and a data processing device known in the art to execute
various control logics. At least one of the various control logics of the slave control unit
20 160 may be combined, and the combined control logics may be written in computerreadable code system and recorded in computer-readable recording media. The recording
media is not limited to a particular type and includes any type that can be accessed by a
processor included in a computer. For example, the recording media includes at least one
15
selected from the group consisting of ROM, RAM, a register, CD-ROM, a magnetic tape, a
hard disk, a floppy disk and an optical data recording device. Additionally, the code
system may be modulated to a carrier signal and included in a communication carrier at a
particular time point and may be stored and executed in computers connected via a
5 network in distributed manner. Additionally, functional programs, codes and code
segments for implementing the combined control logics may be readily inferred by
programmers in the technical field to which the present disclosure belongs.
FIG. 4 is a schematic diagram showing configuration of the master BMS 200
shown in FIG. 1.
10 Referring to FIG. 4, the master BMS 200 may include a master memory 210, a
master communication unit 220, a master power supply unit 230 and a master control unit
240.
The master memory 210 may store an ID table. The ID table includes each ID
allocated to the plurality of slave BMSs.
15 The master memory 210 is not limited to a particular type and includes any known
information storage means capable of recording, deleting, updating and reading data. For
example, the master memory 210 may be DRAM, SDRAM, flash memory, ROM,
EEPROM and a register. The master memory 210 may store program codes defining the
processes that can be executed by the master control unit 240.
20 The master memory 210 may be physically separated from the master control unit
240, and may be integrated into a chip with the master control unit 240.
The master communication unit 220 includes a master antenna 221 and a master
communication circuit 222. The master antenna 221 and the master communication
16
circuit 222 are operably connected to each other. The master communication circuit 222
may demodulate the wireless signal received through the master antenna 221.
Additionally, the master communication circuit 222 may modulate a signal to transmit to
each slave BMS 100, and transmit the modulated signal wirelessly through the master
5 antenna 221. The master antenna 221 may selectively transmit the wireless signal
corresponding to the signal modulated by the master communication unit 220 to at least
one of the plurality of slave BMSs 100-1~100-3.
The master power supply unit 230 generates at least one power source voltage
using electrical energy supplied from at least one battery module 20, an external power
10 source or its own power source. The power source voltage generated by the master power
supply unit 230 may be supplied to the master memory 210 and the master communication
unit 220. Additionally, the power source voltage generated by the master power supply
unit 230 may be supplied to each processor included in the master control unit 240.
The master control unit 240 includes at least one processor, and is operably
15 connected to the master memory 210 and the master communication unit 220. The
master control unit 240 is configured to manage the overall operation of the master BMS
200. Additionally, the master control unit 240 may calculate the State Of Charge (SOC)
and/or State Of Health (SOH) of each of the plurality of battery modules 20-1~20-3 based
on the wireless signals corresponding to sensing information from each of the plurality of
20 slave BMSs 100-1~100-3 among the wireless signals received through the master antenna
221. Additionally, the master control unit 240 may generate information for controlling
the charging, discharging and/or balancing of each of the plurality of slave BMSs 100
based on the calculated SOC and/or SOH, and selectively transmit it to at least one of the
17
plurality of slave BMSs 100-1~100-3 through the master antenna 221 and the master
communication unit 220.
Each processor included in the master control unit 240 may selectively include a
processor, an application-specific integrated circuit (ASIC), a chipset, a logic circuit, a
5 register, a communication modem and a data processing device known in the art to execute
various control logics. At least one of the various control logics of the master control unit
240 may be combined, and the combined control logics may be written in computerreadable code system and recorded in computer-readable recording media. The recording
media is not limited to a particular type and includes any type that can be accessed by a
10 processor included in a computer. For example, the recording media includes at least one
selected from the group consisting of ROM, RAM, a register, CD-ROM, a magnetic tape, a
hard disk, a floppy disk and an optical data recording device. Additionally, the code
system may be modulated to a carrier signal and included in a communication carrier at a
particular time point and may be stored and executed in computers connected via a
15 network in distributed manner. Additionally, functional programs, codes and code
segments for implementing the combined control logics may be readily inferred by
programmers in the technical field to which the present disclosure belongs.
Referring to FIGS. 1 to 4, the master BMS 200 transmits a wireless signal
(hereinafter referred to as a 'first RF signal') including a state detection command to the
20 plurality of slave BMSs 100-1~100-3.
In each prededetermined cycle or in response to the first RF signal, each slave
BMS 100 detects state information of the battery module 20 to which the slave BMS 100 is
coupled. The state information of the battery module 20 represents the voltage, current
18
and/or temperature of the battery module 20. Optionally, the state information of the
battery module 20 may further include state information of each battery cell 21 included in
the battery module 20. The state information of the battery cell 21 represents the voltage,
current and/or temperature of each of the battery cell 21.
5 Each slave BMS 100 is configured to transmit a wireless signal (hereinafter
referred to as a 'second RF signal') indicating the state information of the battery module
20 to the master BMS 200.
The master BMS 200 receives the second RF signal from each of the plurality of
slave BMSs 100-1~100-3 through the master antenna 221. The master BMS 200
10 calculates the module residual capacity of each of the plurality of battery modules 20-
1~20-3 based on the second RF signal received from each of the plurality of slave BMSs
100-1~100-3. The module residual capacity represents the State Of Charge (SOC) of the
battery module 20.
Optionally, the master BMS 200 may further calculate the cell residual capacity of
15 each battery cell 21 included in each of the plurality of battery modules 20-1~20-3 based
on the second RF signal received from each of the plurality of slave BMSs 100-1~100-3.
The cell residual capacity represents the SOC of the battery cell 21.
Subsequently, the master BMS 200 determines the wireless balancing time for
each of the plurality of battery modules 20-1~20-3 according to one of a first balancing
20 rule and a second balancing rule. The first balancing rule may be for determining the
wireless balancing time for each of the plurality of battery modules 20-1~20-3 based on the
module residual capacity of each of the plurality of battery modules 20-1~20-3. The
second balancing rule may be for determining the wireless balancing time for each of the
19
plurality of battery modules 20-1~20-3 based on the cell residual capacity of each battery
cell 21 included in each of the plurality of battery modules 20-1~20-3.
The master BMS 200 may store the wireless balancing time determined for each of
the plurality of slave BMSs 100-1~100-3 in the master memory 210. Along with this or
5 aside from this, the master BMS 200 generates a module balancing command indicating
the wireless balancing time determined for each of the plurality of slave BMSs 100-1~100-
3. Subsequently, the master BMS 200 may transmit a wireless signal (hereinafter referred
to as a 'third RF signal') includng the module balancing command to the plurality of slave
BMSs 100-1~100-3.
10 Each of the plurality of slave BMSs 100-1~100-3 receives the third RF signal
through the slave antenna 121. Each of the plurality of slave BMSs 100-1~100-3 stores
its wireless balancing time determined by the master BMS 200 in the slave memory 110
according to the module balancing command included in the received third RF signal.
Additionally, each of the plurality of slave BMSs 100-1~100-3 transmits a wireless signal
15 (hereinafter referred to as a 'fourth RF signal') during its wireless balancing time
determined by the master BMS 200 using electrical energy of the battery module 20 to
which the slave BMS 100-1~100-3 is coupled. In this case, the fourth RF signal may be
transmitted with the maximum power that is preset for the slave antenna 121.
Each of the first to third RF signals is a wireless signal transmitted and received
20 through a first wireless channel. In contrast, the fourth RF signal is a wireless signal
transmitted by each slave BMS 100 through a second wireless channel. In this instance,
the first wireless channel is a communication channel, and has a preset first frequency
range. In contrast, the second wireless channel is a non-communication channel, and has
20
a preset second frequency range that is separated from the first frequency range. The
slave communication units 120 of each slave BMS 100 are designed to selectively access
the first and second wireless channels. In contrast, the mast communication unit 220 of
the master BMS 200 may be designed to access only the first wireless channel among the
5 first and second wireless channels. Accordingly, the fourth RF signal may not affect the
operation of the master BMS 200.
The following is a detailed description of each of embodiments in which the
master BMS 200 controls the plurality of slave BMSs 100-1~100-3 to reduce a module
residual capacity deviation between the plurality of battery modules 20-1~20-3 and a cell
10 residual capacity deviation between the plurality of battery cells 21 included in each
battery module 20. In each embodiment, assume that electrical energy consumed from
each battery module 20 by the operation other than module balancing and cell balancing is
so small to be negligible, compared to electrical energy consumed from each battery
module 20 by module balancing and cell balancing.
15 FIGS. 5 and 6 are diagrams for reference in describing the operation of balancing
the plurality of battery modules according to the first balancing rule by the wireless battery
management system 30 according to an embodiment of the present disclosure.
FIG. 5 shows one examplary state before determining the wireless balancing time
for each of the plurality of battery modules 20-1~20-3.
20 Referring to FIG. 5, the cell residual capacities of three battery cells 21-1~21-3
included in the first battery module 20-1 are 3.0kAh, 3.1kAh and 3.0kAh respectively, the
cell residual capacities of three battery cells 21-4~21-6 included in the second battery
module 20-2 are 3.3kAh, 3.1kAh and 3.0kAh respectively, and the cell residual capacities
21
of three battery cells 21-7~21-9 included in the third battery module 20-3 are 3.2kAh,
3.2kAh and 3.3kAh respectively. Accordingly, the module residual capacity of the first
battery module 20-1 is 9.1kAh, the module residual capacity of the second battery module
20-2 is 9.4kAh, and the module residual capacity of the third battery module 20-3 is
5 9.7kAh. Here, kAh is an abbreviation of kilo ampere hour, and is a unit that indicates the
residual capacity.
The master BMS 200 sets the module residual capacity of one of the plurality of
battery modules 20-1~20-3 as first target residual capacity. In the first balancing rule, the
smallest module residual capacity 9.1KAh among the module residual capacities 9.1kAh,
10 9.4kAh and 9.7kAh of the plurality of battery modules 20-1~20-3 may be set as the first
target residual capacity.
The master BMS 200 determines the wireless balancing time for each of the
plurality of battery modules 20-1~20-3 based on the differences between the first target
residual capacity 9.1kAh and each of the other module residual capacities 9.4kAh, 9.7kAh.
15 Specifically, the master BMS 200 determines the wireless balancing time for the second
battery module 20-2 based on the difference 0.3kAh between the first target residual
capacity 9.1kAh and the module residual capacity 9.4kAh of the second battery module
20-2. Additionally, the master BMS 200 determines the wireless balancing time for the
third battery module 20-3 based on the difference 0.6KAh between the first target residual
20 capacity 9.1kAh and the module residual capacity 9.7kAh of the third battery module 20-3.
In this instance, with the increasing difference between the module residual
capacity of each battery module 20 and the first target residual capacity, the wireless
balancing time determined for each battery module 20 may increase. For example, the
22
wireless balancing time ('D3' in FIG. 6) determined for the third battery module 20-3 is
longer than the wireless balancing time ('D2' in FIG. 6) determined for the second battery
module 20-2.
Meanwhile, there is no need for module balancing of the first battery module 20-1
5 having the same module residual capacity as the first target residual capacity 9.1kAh.
Accordingly, the master BMS 200 may determine the wireless balancing time for the first
battery module 20-1 having the same module residual capacity as the first target residual
capacity 9.1kAh to be equal to the reference time (for example, 0 sec).
FIG. 6 is a timing chart illustrating the operation for balancing the plurality of
10 battery modules 20-1~20-3 shown in FIG. 5 by the wireless battery management system 30.
Referring to FIG. 6, between time points T1 and T2, the master BMS 200
transmits the first RF signal 601 to the plurality of slave BMSs 100-1~100-3 through the
first wireless channel. At the time point T1, a difference between the smallest and second
smallest of the module residual capacities of the plurality of battery modules 20-1~20-3
15 may be less than first threshold. When the difference between the smallest and second
smallest of the module residual capacities of the plurality of battery modules 20-1~20-3 is
less than the first threshold, module balancing may be stopped.
Between time points T2 and T3, in response to the first RF signal 601, each of the
plurality of slave BMSs 100-1~100-3 detects state information of each of the battery
20 modules 20-1~20-3 to which the slave BMS 100-1~100-3 is coupled.
Between time points T3 and T4, each of the plurality of slave BMSs 100-1~100-3
transmits the second RF signal 611, 621, 631 indicating the state information (see FIG. 5)
detected from the battery modules 20-1~20-3 to which each of the slave BMS 100-1~100-3
23
is coupled to the master BMS 200 through the first wireless channel.
Between time points T4 and T5, the master BMS 200 determines the wireless
balancing time for each of the plurality of battery modules 20-1~20-3 based on the second
RF signal 611, 621, 631.
5 Between time points T5 and T6, the master BMS 200 transmits the first RF signal
602 and the third RF signal 603 to the plurality of slave BMSs 100-1~100-3 through the
first wireless channel. The third RF signal 603 includes a module balancing command
indicating the wireless balancing time determined for each of the plurality of battery
modules 20-1~20-3.
10 As described above, the wireless balancing time for the first battery module 20-1
may be 0 sec. Accordingly, the first slave BMS 100-1 does not perform module
balancing of the first battery module 20-1. Between time points T6 and T7, in response to
the first RF signal 602, the first slave BMS 100-1 detects state information of the first
battery module 20-1. In this case, until the time point T7, the module residual capacity of
15 the first battery module 20-1 may be maintained at 9.1 kAh. Subsequently, between time
points T7 and T9, the first slave BMS 100-1 may transmit the second RF signal 612
indicating the state information of the first battery module 20-1 to the master BMS 200
through the first wireless channel.
Between time points T6 and T8, the second slave BMS 100-2 transmits the fourth
20 RF signal 622 through the second wireless channel using electrical energy of the second
battery module 20-2 during the wireless balancing time D2 according to the module
balancing command included in the third RF signal 603. Accordingly, after transmission
of the fourth RF signal 622 than before, the module residual capacity of the second battery
24
module 20-2 is closer to the first target residual capacity 9.1 kAh. For example, by
module balancing during the wireless balancing time D2, the cell residual capacities of the
three battery cells 21-4~21-6 are reduced by 0.1kAh and reach 3.2kAh, 3.0kAh and
2.9kAh respectively, and thus the module residual capacity of the second battery module
5 20-2 at the time point T8 may be equal to the first target residual capacity 9.1kAh.
Between time points T6 and T8 or at the time point T8, the second slave BMS
100-2 may detect state information of the second battery module 20-2. From the time
point T6 to the time point T8, cell balancing of the battery cells 21-4~21-6 included in the
second battery module 20-2 may not be performed. That is, from the time point T6 to the
10 time point T8, all the balancing switches SW of the wired balancing unit 140 of the second
slave BMS 100-2 may be turned off. Accordingly, the slave sensing unit 130 of the
second slave BMS 100-2 may detect state information of the second battery module 20-2.
Between time points T8 and T10, the second slave BMS 100-2 transmits the
second RF signal 623 indicating the state information of the second battery module 20-2 to
15 the master BMS 200 through the first wireless channel.
Between time points T6 and T11, the third slave BMS 100-3 transmits the fourth
RF signal 632 through the second wireless channel using electrical energy of the third
battery module 20-3 for the wireless balancing time D3 according to the module balancing
command included in the third RF signal 603. Accordingly, after transmission of the
20 fourth RF signal 632 than before, the module residual capacity of the third battery module
20-3 is closer to the first target residual capacity 9.1kAh. For example, by module
balancing for the wireless balancing time D3, the cell residual capacities of the three
battery cells 21-7~21-9 are reduced by 0.2kAh when compared to FIG. 5 and reach 3.0kAh,
25
3.0kAh and 3.1kAh respectively, and thus the module residual capacity of the third battery
module 20-3 at the time point T11 may be equal to the first target residual capacity 9.1kAh.
Between time points T6 and T11 or at the time point T11, the third slave BMS
100-3 may detect state information of the third battery module 20-3. From the time point
5 T6 to the time point T11, cell balancing of the battery cells 21-7~21-9 included in the third
battery module 20-3 may not be performed. That is, from the time point T6 to the time
point T11, all the balancing switches SW of the wired balancing unit 140 of the third slave
BMS 100-3 may be turned off. Accordingly, the slave sensing unit 130 of the third slave
BMS 100-3 may detect state information of the third battery module 20-3.
10 Between time points T11 and T12, the third slave BMS 100-3 may transmit the
second RF signal 633 indicating the state information of the third battery module 20-3 to
the master BMS 200 through the first wireless channel.
Meanwhile, the module balancing command of the third RF signal 603 is for
reducing a difference in module residual capacities of the plurality of battery modules 20-
15 1~20-3, but not a difference in cell residual capacities of the plurality of battery cells 21
included in the common battery module 20. It is because, as shown in FIG. 5, when one
of the plurality of battery cells 20 connected in series within the same battery module 20 is
discharged, each of the other battery cells is discharged as much during module balancing.
To reduce a difference in cell residual capacity of the plurality of battery cells 21,
20 the wired balancing time for at least one battery cell 21 included in the plurality of battery
modules 20-1~20-3 may be further determined. In this instance, the wired balancing time
determined for each battery cell 21 may be based on a difference between the cell residual
capacity of each battery cell 21 and the minimum cell residual capacity of the battery
26
module 20 including each battery cell 21.
For example, the wired balancing time for the battery cell 21-2 may be determined
based on a difference 0.1kAh between the cell residual capacity 3.1kAh of the battery cell
21-2 and the minimum cell residual capacity 3.0kAh of the first battery module 20-1
5 including the battery cell 21-2. As another example, the wired balancing time for the
battery cell 21-4 may be determined based on a difference 0.3kAh between the cell
residual capacity 3.3kAh of the battery cell 21-4 and the minimum cell residual capacity
3.0kAh of the second battery module 20-2 including the battery cell 21-4.
The master BMS 200 may further include a cell balancing command in the third
10 RF signal 603. The cell balancing command may represent the wired balancing time for
at least one battery cell 21 included in the plurality of battery modules 20-1~20-3.
The first slave BMS 100-1 may perform selective cell balancing of the three
battery cells 21-1~21-3 by controlling the wired balancing unit 140 included in the first
slave BMS 100-1 according to the cell balancing command of the third RF signal 603.
15 After the time point T9, the first slave BMS 100-1 may discharge at least one of the three
battery cells 21-1~21-3 by controlling the balancing switch SW of the wired balancing unit
140. T13 may be the time point at which the master BMS 200 transmits a new third RF
signal through the first wireless channel.
For example, the first slave BMS 100-1 may turn on the balancing switch SW
20 connected between two ends of the battery cell 21-2, and turn off the balancing switch SW
connected between two ends of each of the other battery cells 21-1, 21-3 to reduce the cell
residual capacity of the battery cell 21-2 by 0.1kAh. In this instance, the balancing switch
SW connected between two ends of the battery cell 21-2 may be turned on for the wired
27
balancing time determined for the battery cell 21-2. Accordingly, at an arbitrary time
point after the time point T9, the cell residual capacities of the three battery cells 21-1~21-
3 may be all equalized and reach 3.0kAh respectively. That is, the module residual
capacity of the first battery module 20-1 may be 9.0kAh.
5 The second slave BMS 100-2 may perform selective cell balancing of the three
battery cells 21-4~21-6 by controlling the wired balancing unit 140 according to the cell
balancing command of the third RF signal 603. For at least some time between the time
points T10 and T13, the second slave BMS 100-2 may discharge at least one of the three
battery cells 21-4~21-6 by controlling the balancing switch SW of the wired balancing unit
10 140. For example, the second slave BMS 100-2 may turn on the balancing switch SW
connected between two ends of the battery cell 21-4 to reduce the cell residual capacity of
the battery cell 21-4 by 0.3kAh, turn on the balancing switch SW connected between two
ends of the battery cell 21-5 to reduce the cell residual capacity of the battery cell 21-5 by
0.1kAh, and turn off the balancing switch SW connected between two ends of the
15 remaining battery cell 21-6. In this instance, the balancing switch SW connected between
two ends of the battery cell 21-4 may be turned on for the wired balancing time determined
for the battery cell 21-4. Additionally, the balancing switch SW connected between two
ends of the battery cell 21-5 may be turned on for the wired balancing time determined for
the battery cell 21-5. Accordingly, at an arbitrary time point after the time point T10, the
20 cell residual capacities of the three battery cells 21-4~21-6 may be all equalized and reach
2.9kAh respectively. That is, the module residual capacity of the second battery module
20-2 may be 8.7kAh.
The third slave BMS 100-3 may perform selective cell balancing of the three
28
battery cells 21-7~21-9 by controlling the wired balancing unit 140 according to the cell
balancing command of the third RF signal 603. For at least some time between the time
points T12 and T13, the third slave BMS 100-3 may discharge at least one of the three
battery cells 21-7~21-9 by controlling the balancing switch SW of the wired balancing unit
5 140. For example, the third slave BMS 100-3 may turn off the balancing switch SW
connected between two ends of the battery cell 21-8, turn on the balancing switch SW
connected between two ends of the battery cell 21-9 to reduce the cell residual capacity of
the battery cell 21-9 by 0.1kAh, and turn off the balancing switch SW connected between
two ends of the remaining battery cell 21-7. In this instance, the balancing switch SW
10 connected between two ends of the battery cell 21-9 may be turned on for the wired
balancing time determined for the battery cell 21-9. Accordingly, at an arbitrary time
point after the time point T12, the cell residual capacities of the three battery cells 21-
7~21-9 may be all equalized and reach 3.0kAh respectively. That is, the module residual
capacity of the third battery module 20-3 may be 9.0kAh.
15 Meanwhile, although not shown, after the time point T13, the first and third slave
BMSs 100-1, 100-3 may reduce the module residual capacities of each of the first and third
battery modules 20-1, 20-3 by 0.3kAh according to the module balancing command
included in a new third RF signal from the master BMS 200. Accordingly, the module
residual capacities of the first to third battery modules 20-1~20-3 are all equalized and
20 reach 8.7kAh.
FIGS. 7 and 8 are diagrams for reference in describing the operation of balancing
the plurality of battery modules according to the second balancing rule by the wireless
battery management system 30 according to an embodiment of the present disclosure.
29
FIG. 7 shows other examplary state before determining the wireless balancing time
for each of the plurality of battery modules 20-1~20-3.
Referring to FIG. 7, as opposed to FIG. 6, the cell residual capacities of the three
battery cells 21-1~21-3 included in the first battery module 20-1 are 3.0kAh, 3.1kAh,
5 3.0kAh respectively, the cell residual capacities of the three battery cells 21-4~21-6
included in the second battery module 20-2 are 3.2kAh, 3.0kAh, 2.9kAh respectively, and
the cell residual capacities of the three battery cells 21-7~21-9 included in the third battery
module 20-3 are 3.1kAh, 3.2kAh, 3.1kAh respectively. Accordingly, the module residual
capacity of the first battery module 20-1 is 9.1kAh, the module residual capacity of the
10 second battery module 20-2 is 9.1kAh, and the module residual capacity of the third
battery module 20-3 is 9.4kAh.
The master BMS 200 sets one of all the battery cells 21-1~21-9 included in the
plurality of battery modules 20-1~20-3 as second target residual capacity. In the second
balancing rule, a smallest one of all the battery cells 21-1~21-9 included in the plurality of
15 battery modules 20-1~20-3 is determined as the second target residual capacity. In FIG. 7,
the cell residual capacity 2.9kAh of the battery cell 21-6 is set as the second target residual
capacity.
Additionally, the master BMS 200 determines the minimum cell residual capacity
of each of the plurality of battery modules 20-1~20-3. In the state of FIG. 7, the
20 minimum cell residual capacity of the first battery module 20-1 is determined as the cell
residual capacity 3.0kAh of the battery cell 21-1 or the battery cell 21-3, the minimum cell
residual capacity of the second battery module 20-2 is determined as the cell residual
capacity 2.9kAh of the battery cell 21-6, and the minimum cell residual capacity of the
30
third battery module 20-3 is determined as the cell residual capacity 3.1kAh of the battery
cell 21-7 or the battery cell 21-9.
The master BMS 200 may determine the wireless balancing time for each of the
plurality of battery modules 20-1~20-3 based on the differences between the second target
5 residual capacity and the minimum cell residual capacities of each of the other battery
modules 20.
Specifically, the master BMS 200 determines the wireless balancing time for the
first battery module 20-1 based on the difference 0.1kAh between the second target
residual capacity 2.9kAh and the minimum cell residual capacity 3.0kAh of the first
10 battery module 20-1.
Additionally, the master BMS 200 determines the wireless balancing time for the
third battery module 20-3 based on the difference 0.2kAh between the second target
residual capacity 2.9kAh and the minimum cell residual capacity 3.1kAh of the third
battery module 20-3.
15 In this instance, with the increasing difference between the minimum cell residual
capacity of each battery module 20 and the second target residual capacity, the wireless
balancing time determined for each battery module 20 may increase. For example, the
wireless balancing time for the first battery module 20-1 may correspond to 0.3kAh that is
obtained by multiplying the difference 0.1kAh by the number (3) of battery cells 21
20 included in the first battery module 20-1, and the wireless balancing time for the third
battery module 20-3 may correspond to 0.6kAh that is obtained by multiplying the
difference 0.2kAh by the number (3) of battery cells 21 included in the third battery
module 20-3.
31
Accordingly, in the state of FIG. 7, the wireless balancing time ('D13' in FIG. 8)
for the third battery module 20-3 is longer than the wireless balancing time ('D11' in FIG.
8) for the first battery module 20-1.
Meanwhile, the second target residual capacity 2.9kAh is equal to the minimum
5 cell residual capacity 2.9kAh of the second battery module 20-1. In this case, the master
BMS 200 may determine the wireless balancing time for the second battery module 20-1 to
be equal to the reference time (for example, 0 sec).
FIG. 8 is a timing chart illustrating the operation of balancing the plurality of
battery modules 20-1~20-3 shown in FIG. 7 by the wireless battery management system 30.
10 Referring to FIG. 8, between time points T21 and T22, the master BMS 200
transmits the first RF signal 701 to the plurality of slave BMSs 100-1~100-3 through the
first wireless channel. Before the time point T21, a difference between the smallest and
second smallest of the minimum cell residual capacities of the plurality of battery modules
20-1~20-3 may be less than second threshold. When a difference between the smallest
15 and second smallest of the minimum cell residual capacities of the plurality of battery
modules 20-1~20-3 is less than the second threshold, module balancing may be stopped.
Between time points T22 and T23, in response to the first RF signal 701, each of
the plurality of slave BMSs 100-1~100-3 detects state information of the battery module
20 to which the slave BMS 100-1~100-3 is coupled.
20 Between time points T23 and T24, each of the plurality of slave BMSs 100-1~100-
3 transmits the second RF signal 711, 721, 731 indicating the state information (see FIG. 7)
detected from the battery module 20-1, 20-3, 20-3 in which the slave BMS 100-1~100-3 is
installed to the master BMS 200 through the first wireless channel.
32
Between time points T24 and T25, the master BMS 200 determines the wireless
balancing time for each of the plurality of battery modules 20-1~20-3 based on the second
RF signal 711, 721, 731.
Between time points T25 and T26, the master BMS 200 transmits the first RF
5 signal 702 and the third RF signal 703 to the plurality of slave BMSs 100-1~100-3 through
the first wireless channel. The third RF signal 703 includes a module balancing
command indicating the wireless balancing time determined for each of the plurality of
battery modules 20-1~20-3.
Between time points T26 and T28, the first slave BMS 100-1 transmits the fourth
10 RF signal 712 through the second wireless channel for the wireless balancing time D11
using electrical energy of the first battery module 20-1 according to the module balancing
command included in the third RF signal 703. Accordingly, after transmission of the
fourth RF signal 712 than before, the minimum cell residual capacity of the first battery
module 20-1 is closer to the second target residual capacity 2.9kAh. For example, by
15 module balancing for the wireless balancing time D11, the cell residual capacities of the
three battery cells 21-1~21-3 are reduced by 0.1kAh and reach 2.9kAh, 3.0kAh and
2.9kAh respectively, and thus the minimum cell residual capacity of the first battery
module 20-1 at the time point T28 may be equal to the second target residual capacity
2.9kAh.
20 Between time points T26 and T28 or at the time point T28, the first slave BMS
100-1 may detect state information of the first battery module 20-1. From the time point
T26 to the time point T28, cell balancing of the battery cells 21-1~21-3 included in the first
battery module 20-1 may not be performed. That is, from time points T26 to T28, all the
33
balancing switches SW of the wired balancing unit 140 of the first slave BMS 100-1 may
be turned off. Accordingly, the slave sensing unit 130 of the first slave BMS 100-1 may
detect state information of the first battery module 20-1.
Between time points T28 and T30, the first slave BMS 100-1 transmits the second
5 RF signal 713 indicating the state information of the first battery module 20-1 to the master
BMS 200 through the first wireless channel.
As described above, the wireless balancing time for the second battery module 20-
2 may be 0 sec. Accordingly, the second slave BMS 100-2 does not perform module
balancing of the second battery module 20-2. Between time points T26 and T27, in
10 response to the first RF signal 702, the second slave BMS 100-2 detects state information
of the second battery module 20-2. In this case, until the time point T27, the module
residual capacity of the second battery module 20-2 may be maintained at 9.1kAh.
Between time points T27 and T29, the second slave BMS 100-2 transmits the second RF
signal 722 indicating the state information of the second battery module 20-2 to the master
15 BMS 200 through the first wireless channel.
Between time points T26 and T31, the third slave BMS 100-3 transmits the fourth
RF signal 732 through the second wireless channel for the wireless balancing time D13
using electrical energy of the third battery module 20-3 according to the module balancing
command included in the third RF signal 703. Accordingly, after transmission of the
20 fourth RF signal 732 than before, the minimum cell residual capacity of the third battery
module 20-3 is closer to the second target residual capacity 2.9kAh. For example, by
module balancing for the wireless balancing time D13, the cell residual capacities of the
three battery cells 21-7~21-9 are reduced by 0.2kAh when compared to FIG. 7 and reach
34
2.9kAh, 3.0kAh and 2.9kAh respectively, and thus the minimum cell residual capacity of
the third battery module 20-3 at T31 may be equal to the second target residual capacity
2.9kAh.
Between time points T26 and T31 or at the time point T31, the third slave BMS
5 100-3 may detect state information of the third battery module 20-3. From the time point
T26 to the time point T31, cell balancing of the battery cells 21-7~21-9 included in the
third battery module 20-3 may not be performed. That is, from the time point T26 to the
time point T31, all the balancing switches SW of the wired balancing unit 140 of the third
slave BMS 100-3 may be turned off. Accordingly, the slave sensing unit 130 of the third
10 slave BMS 100-3 may detect state information of the third battery module 20-3.
Between time points T31 and T32, the third slave BMS 100-3 may transmit the
second RF signal 733 indicating the state information of the third battery module 20-3 to
the master BMS 200 through the first wireless channel.
Meanwhile, the module balancing command of the third RF signal 703 is for
15 equalizing the minimum cell residual capacities of the plurality of battery modules 20-
1~20-3, but not reducing a difference in cell residual capacities of the plurality of battery
cells 21 included in the common battery module 20. It is because, as shown in FIG. 7,
when one of the plurality of battery cells 20 connected in series within the same battery
module 20 is discharged, each of the other battery cells is discharged as much during
20 module balancing.
To reduce a difference in cell residual capacities of the plurality of battery cells 21
included in each battery module 20 for each battery module 20, the master BMS 200 may
further include a cell balancing command in the third RF signal 703.
35
The first slave BMS 100-1 may perform selective cell balancing of the three
battery cells 21-1~21-3 by controlling the wired balancing unit 140 according to the cell
balancing command of the third RF signal 703. For at least some time between the time
points T30 and T33, the first slave BMS 100-1 may discharge at least one of the three
5 battery cells 21-1~21-3 by controlling the balancing switch SW of the wired balancing unit
140. The time point T33 may be the time point at which the master BMS 200 transmits a
new third RF signal through the first wireless channel.
For example, the first slave BMS 100-1 may turn on the balancing switch SW
connected between two ends of the battery cell 21-2 and turn off the balancing switch SW
10 connected between two ends of each of the other battery cells 21-1, 21-3 to reduce the cell
residual capacity of the battery cell 21-2 by 0.1kAh. In this instance, the balancing switch
SW connected between two ends of the battery cell 21-2 may be turned on for the wired
balancing time determined for the battery cell 21-2. Accordingly, at an arbitrary time
point after the time point T30, the cell residual capacities of the three battery cells 21-
15 1~21-3 may be all equalized and reach 2.9kAh. That is, the module residual capacity of
the first battery module 20-1 may be 8.7kAh.
The second slave BMS 100-2 may perform selective cell balancing of the three
battery cells 21-4~21-6 by controlling the wired balancing unit 140 according to the cell
balancing command of the third RF signal 703. For at least some time between time
20 points T29 and T33, the second slave BMS 100-2 may discharge at least one of the three
battery cells 21-4~21-6 by controlling the balancing switch SW of the wired balancing unit
140.
For example, the second slave BMS 100-2 may turn on the balancing switch SW
36
connected between two ends of the battery cell 21-4 to reduce the cell residual capacity of
the battery cell 21-4 by 0.3kAh, turn on the balancing switch SW connected between two
ends of the battery cell 21-5 to reduce the cell residual capacity of the battery cell 21-5 by
0.1kAh, and turn off the balancing switch SW connected between two ends of the
5 remaining battery cell 21-6. In this instance, the balancing switch SW connected between
two ends of the battery cell 21-4 may be turned on for the wired balancing time determined
for the battery cell 21-4. Additionally, the balancing switch SW connected between two
ends of the battery cell 21-5 may be turned on for the wired balancing time determined for
the battery cell 21-5. Accordingly, at an arbitrary time point after T29, the cell residual
10 capacities of the three battery cells 21-4~21-6 may be all equalized and reach 2.9kAh.
That is, the module residual capacity of the second battery module 20-2 may be 8.7kAh.
The third slave BMS 100-3 may perform selective cell balancing of the three
battery cells 21-7~21-9 by controlling the wired balancing unit 140 according to the cell
balancing command of the third RF signal 703. For at least some time between time
15 points T32 and T33, the third slave BMS 100-3 may discharge at least one of the three
battery cells 21-7~21-9 by controlling the balancing switch SW of the wired balancing unit
140.
For example, the third slave BMS 100-3 may turn on the balancing switch SW
connected between two ends of the battery cell 21-8 to reduce the cell residual capacity of
20 the battery cell 21-8 by 0.1kAh, and turn off the balancing switch SW connected between
two ends of each of the remaining battery cells 21-7, 21-9. In this instance, the balancing
switch SW connected between two ends of the battery cell 21-8 may be turned on for the
wired balancing time determined for the battery cell 21-8. Accordingly, at an arbitrary
37
time point after the time point T32, the cell residual capacities of the three battery cells 21-
7~21-9 may be all equalized and reach 2.9kAh. That is, the module residual capacity of
the third battery module 20-3 may be 8.7kAh.
Meanwhile, although the embodiments describe that the module balancing
5 operation is performed earlier than the cell balancing operation with reference to FIGS. 5
to 8, the scope of the present disclosure is not limited thereto. That is, the wireless battery
management system 30 may perform the cell balancing operation first and then perform
module balancing.
For example, in the state of FIG. 7, when the cell balancing operation is performed
10 first, the residual capacities of all the battery cells 21-1~21-3 of the first battery module 20-
1 are 3.0kAh, the residual capacities of all the battery cells 21-4~21-6 of the second battery
module 20-2 are 2.9kAh, and the residual capacities of all the battery cells 21-7~21-9 of
the third battery module 20-3 are 3.1kAh. It is because the cell balancing operation is
performed by balancing all the other battery cells 21 based on the minimum cell residual
15 capacity of each battery module 20. Subsequently, when the module balancing operation
is performed, the residual capacities of all the battery cells 21-1~21-3 of the first battery
module 20-1 are reduced by 0.1kAh respectively, and the residual capacities of all the
battery cells 21-7~21-9 of the third battery module 20-3 are reduced by 0.2kAh
respectively. Accordingly, it is possible to remove not only a difference in module
20 residual capacity between all the battery modules 20-1~20-3 but also a difference in cell
residual capacity between all the battery cells 21-1~21-9.
The embodiments of the present disclosure described hereinabove are not
implemented only through the apparatus and method, and may be implemented through
38
programs that realize functions corresponding to the configurations of the embodiments of
the present disclosure or recording media having the programs recorded thereon, and this
implementation may be easily achieved by those skilled in the art from the disclosure of
the embodiments previously described.
5 While the present disclosure has been hereinabove described with regard to a
limited number of embodiments and drawings, the present disclosure is not limited thereto
and it is obvious to those skilled in the art that various modifications and changes may be
made thereto within the technical aspects of the present disclosure and the equivalent scope
of the appended claims.
10 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.
15
20
39
WE CLAIM:
1. A wireless battery management system comprising:
a master BMS configured to transmit a first radio frequency (RF) signal including
a state detection command through a first wireless channel; and
a plurality of slave BMSs coupled to a plurality of battery modules in one-to-one
correspondence, wherein each of the plurality of slave BMSs is configured to detect state
information of the battery module to which the slave BMS is coupled in response to the
first RF signal, and transmit a second RF signal indicating the state information of the
battery module through the first wireless channel,
wherein the master BMS is configured to determine a wireless balancing time for
each of the plurality of battery modules based on the second RF signal, and transmit a
third RF signal including a module balancing command indicating the wireless balancing
time to the plurality of slave BMSs through the first wireless channel, and
wherein each of the plurality of slave BMSs is configured to transmit a fourth RF
signal through a second wireless channel during the wireless balancing time using
electrical energy of the battery module to which the corresponding slave BMS is coupled
according to the module balancing command included in the third RF signal.
2. The wireless battery management system according to claim 1, wherein the
first wireless channel has a preset first frequency range, and
wherein the second wireless channel has a preset second frequency range that is
separated from the first frequency range.
3. The wireless battery management system according to claim 1, wherein the
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master BMS is configured to calculate a module residual capacity stored in each of the
plurality of battery modules based on the second RF signal, and determine the wireless
balancing time for each of the plurality of battery modules based on the module residual
capacity of each of the plurality of battery modules.
4. The wireless battery management system according to claim 3, wherein the
master BMS is configured to set the module residual capacity of one of the plurality of
battery modules as a first target residual capacity, and determine the wireless balancing
time for each of the plurality of battery modules based on a difference between the first
target residual capacity and each of the other module residual capacities.
5. The wireless battery management system according to claim 1, wherein the
state information of the battery module includes state information of each battery cell
included in the battery module, and
wherein the master BMS is configured to calculate a cell residual capacity of each
battery cell included in each of the plurality of battery modules based on the second RF
signal, and determine the wireless balancing time for each of the plurality of battery
modules based on the cell residual capacity of each battery cell included in each of the
plurality of battery modules.
6. The wireless battery management system according to claim 5, wherein the
master BMS is configured to determine a smallest cell residual capacity of cell residual
capacities of all battery cells included in the plurality of battery modules as second target
residual capacity, and determine the wireless balancing time for each of the plurality of
battery modules further based on a difference between the second target residual capacity
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and the minimum cell residual capacity of each of the other battery modules.
7. The wireless battery management system according to claim 6, wherein the
master BMS is configured to determine a wired balancing time for each battery cell
included in each of the plurality of battery modules based on a difference between the
minimum cell residual capacity of each of the plurality of battery modules and each of the
other cell residual capacities, and
wherein the third RF signal further includes a cell balancing command indicating
the wired balancing time.
8. The wireless battery management system according to claim 7, wherein
each of the plurality of slave BMSs includes a wired balancing unit electrically connected
to two ends of each battery cell included in the battery module to which the slave BMS is
coupled, and
each of the plurality of slave BMSs is configured to balance the cell residual
capacity of each battery cell included in the battery module to which the corresponding
slave BMS is coupled by controlling the wired balancing unit according to the cell
balancing command included in the third RF signal.
9. A battery pack comprising:
the wireless battery management system according to one of claims 1 to 8; and
the plurality of battery modules.