DESCRIPTION
Title of Invention: POWER RESERVE APPARATUS, POWER SYSTEM,
AND ELECTRIC VEHICLE
Technical Field
The present disclosure relates to a power reserve
apparatus, a power system, and an electric vehicle that
utilizes power from the power reserve apparatus.
Background Art
In these years, the usage of a secondary battery such
as a lithium- ion battery is rapidly expanding to a power
storage apparatus for reserving power and a power storage
battery for a car combined with a new energy system such as
a solar cell or wind power generation, and the like. When a
large number of power storage elements such as, for example,
unit batteries (also called electric batteries or cells; in
the following description, referred to as battery cells as
necessary) are used to generate high power, a configuration
in which a plurality of power storage modules are connected
in series with one another is adopted. In the power storage
modules, a plurality of, that is, for example, four, battery
cells are connected parallel to, and/or in series with, one
another to configure a battery block. A large number of
battery blocks are stored in a protection case to configure
a power storage module (also called an assembled battery) .
Furthermore, a battery system is known in which a
plurality of power storage modules are connected to one
another and a common control apparatus is provided for the
plurality of power storage modules. In this configuration,
each power storage module includes a module controller, and
the module controller and the common control apparatus
communicate with each other through communication means.
In the case of using a plurality of battery cells, even
when one of the plurality of battery cells has reached a
lower limit of working voltage during discharging, other
battery cells may not have still reached the lower limit of
the working voltage due to differences in self -discharge
between the battery cells or the like. When the battery
cells are charged again in such a state, some battery cells
cannot be fully charged, thereby posing a problem in that
the capacity of these battery cells cannot be fully utilized.
In order to correct variation in voltage between the
plurality of battery cells, an equalization process for
controlling the balance between the battery cells is
performed. Because a power reserve apparatus includes an
extremely large number of battery cells in the case of an
on-vehicle battery, a domestic power storage apparatus, or
the like, there has been a problem in that it takes a long
time to equalize the voltages of all the battery cells.
By intra-module equalization (inter-cell voltage
adjustment) , in which a process for equalizing the voltages
of the battery cells is performed for each power storage
module, and inter-module equalization (inter-module voltage
adjustment) , in which a process for equalizing the voltages
of the power storage modules is performed, it is possible to
reduce the time taken to complete the equalization.
As a configuration for equalizing the voltages of a
plurality of battery cells in a power storage module in
which the plurality of battery cells are connected to one
another, a voltage balance circuit (referred to as the
passive balance adjustment circuit) is known in which a
resistor and a switching element are connected parallel to
each cell and that causes a battery cell whose voltage is
high to discharge. Furthermore, in a power reserve
apparatus in which a plurality of power storage modules are
connected to one another, a configuration is known in which,
as with the above example, a resistor element and a
switching element are used to equalize the voltages of the
power storage modules.
However, when voltage is equalized by resistors, the
voltages of the battery cells and the power storage modules
undesirably decrease as a whole, and therefore a large
number of times of charging and a large number of times of
discharging for adjusting the voltages need to be repeated
in order to set these voltages to a target value. Therefore,
it takes a long time to complete the voltage adjustment of
the power reserve apparatus. Especially when there is
cyclic deterioration of a positive/negative active material,
variation in the temperature condition, or a decrease in the
amount of power in a battery cell according to an increase
in internal resistance, the balance between the amounts of
power in the battery cells is lost to a great extent and it
takes a longer time to complete the voltage adjustment.
Furthermore, the variation of the battery cells cannot be
adjusted between the modules, and it is difficult to keep
the balance .
On the other hand, a circuit (referred to as an active
balance adjustment circuit) has been proposed that equalizes
voltage using coils and switching elements. In a circuit
configuration that equalizes voltage by moving electric
charge using coils, voltage can be equalized in a relatively
short period of time, but the arrangement of the coils and
the switching elements and the control of the switching
elements are complex, and a large number of coils need to be
arranged in such a way as to enable smooth transmission of
power .
For example, in Patent Literature 1 , a large number of
battery cells are divided into a plurality of series cell
groups, while providing an inter-cell voltage balance
correction circuit for each cell group and an inter-group
voltage balance correction circuit. The inter-cell balance
correction circuit equalizes the voltages of cells in each
cell group using inductors and switching elements. The
inter-group voltage balance correction circuit has a
configuration in which the balance between the series
voltages of the cell groups is corrected by alternatingcurrent
coupling formed by transformer coils and switching
circuits .
Citation List
Patent Literature
PTL 1 : Japanese Unexamined Patent Application
Publication No. 2008-035680
Summary of Invention
Technical Problem
The inter-group voltage balance correction circuit
described in Patent Literature 1 can be applied to
correction of the balance between batteries in power storage
modules. However, a coil is configured to be connected to
each cell group (for example, two battery cells) . The coils
are configured to be wound on the same magnetic core.
Therefore, when the inter-group voltage balance correction
circuit has been connected to a plurality of power storage
modules stored in different cases, coils and magnetic cores
need to be stored in the different cases. Because starshaped
wiring is adopted in which a plurality of power
storage modules are connected to this different transformer
apparatus, there is a problem in that connection becomes
complex when the number of power storage modules increases .
Furthermore, even if an extremely large number of battery
cells are divided into cell groups, an extremely large
number of inductors are needed when each group is configured
by two cells. This results in an increase in the number of
components, thereby causing the areas of circuit boards to
increase.
Furthermore, because voltage is equalized by
controlling the switching circuits in such a way as to turn
on and off in the same phase, it is impossible to
independently control the switching operation for each cell
group. Therefore, there has been a problem in that power
cannot be transmitted from a particular cell group whose
voltage is high to a particular cell group whose voltage is
low .
Therefore, an object of the present invention is to
provide a power reserve apparatus, a power system, and an
electric vehicle that can reduce the time taken to complete
the voltage adjustment without requiring a large number of
inductors .
Solution to Problem
In order to solve the above problem, the present
disclosure includes a power reserve apparatus comprising a
first module that includes a first set of battery cells and
a first inter-cell balance adjustment unit configured to use
passive balancing to reduce voltage variance among the first
set of battery cells. The power reserve apparatus also
comprises a second module that includes a second set of
battery cells and a second inter-cell balance adjustment
unit configured to use passive balancing to reduce voltage
variance among the second set of battery cells. The power
reserve apparatus further comprises an inter -module balance
adjustment unit configured to use active balancing to reduce
voltage variance among the first and second modules.
More preferably, in the present disclosure, the first
module further includes a first battery monitoring unit
configured to detect voltages of each of the battery cells
within the first set and the second module further includes
a second battery monitoring unit configured to detect
voltages of each of the battery cells within the second set.
Additionally, in the present disclosure, the first
module further includes a first control unit configured to
determine which switches within the first inter-cell balance
adjustment unit are to be switched to passively reduce
voltage variance among the first set of battery cells based
on the voltages detected by the first battery monitoring
unit and the second module further includes a second control
unit configured to determine which switches within the
second inter-cell balance adjustment unit are to be switched
to passively reduce voltage variance among the second set of
battery cells based on the voltages detected by the second
battery monitoring unit.
Further, in the present disclosure, the power reserve
apparatus also includes a battery controller configured to
receive a first cumulative voltage of the first set of
battery cells within the first module from the first control
unit, receive a second cumulative voltage of the second set
of battery cells within the second module from the second
control unit, and transmit control information to the first
and second modules indicating which switches of the inter
module balance adjustment unit are to be switched to
actively reduce voltage variance among the first and second
modules .
In another embodiment, a power reserve method comprises
detecting voltages of a first set of battery cells in a
first module and detecting voltages of a second set of
battery cells in a second module. The method also comprises
determining a first cumulative voltage of the first module
based on the voltages of the first set of battery cells and
determining a second cumulative voltage of the second module
based on the voltages of the second set of battery cells.
The method further comprises controlling a first group of
switches to actively balance the cumulative voltages among
the first and second modules and controlling a second group
of switches to passively balance voltages among the battery
cells within the first module and voltages among battery
cells within the second module.
In another embodiment, a electric vehicle comprises a
power reserve apparatus that includes a first module
including a first set of battery cells and a first intercell
balance adjustment unit configured to use passive
balancing to reduce voltage variance among the first set of
battery cells. The power reserve apparatus also includes a
second module including a second set of battery cells and a
second inter-cell balance adjustment unit configured to use
passive balancing to reduce voltage variance among the
second set of battery cells. The power reserve apparatus
further includes an inter-module balance adjustment unit
configured to use active balancing to reduce voltage
variance among the first and second modules and a conversion
apparatus configured to use power supplied from the power
reserve apparatus to drive an engine and power vehicle
control electronics.
Advantageous Effects of Invention
In the present disclosure, since inter-cell voltage
adjustment (referred to as inter-cell balance adjustment or
cell balance) is performed using passive balance control,
the sizes of circuits and circuit boards can be reduced
without requiring inductor elements. On the other hand,
since inter-module voltage adjustment (referred to as inter¬
module balance adjustment or inter-module balance) is
performed using active balance control, it is possible to
prevent the overall voltage from decreasing. Furthermore,
when the inter-module balance adjustment is performed, a
difference in voltage larger than in the case of the intercell
balance adjustment needs to be eliminated, and
therefore when the inter-module balance adjustment is
performed using the passive balance adjustment, the time
taken to complete the balance adjustment becomes longer.
Therefore, as in the present disclosure, by combining the
inter-cell balance adjustment and the inter-module balance
adjustment, the time taken to complete the balance
adjustment is reduced.
Brief Description of Drawings
Fig. 1 is a block diagram of an example of a power
reserve apparatus.
Fig. 2A is a block diagram illustrating passive balance
adjustment. Figs. 2B, 2C, and 2D are schematic diagrams
illustrating the passive balance adjustment.
Fig. 3A is a block diagram illustrating active balance
adjustment. Figs. 3B, 3C, and 3D are schematic diagrams
illustrating the active balance adjustment.
Fig. 4 is a connection diagram illustrating an example
of an inter-module balance adjustment circuit having the
same configuration as the related art.
Fig. 5 is a connection diagram illustrating a first
example of the inter-module balance adjustment circuit.
Fig. 6 is a connection diagram illustrating a second
example of the inter-module balance adjustment circuit.
Fig. 7 is a connection diagram illustrating a specific
example of switches .
Fig. 8 is a connection diagram illustrating the
operation of the second example of the inter-module balance
adjustment circuit.
Figs. 9A, 9B, 9C, and 9D are timing charts illustrating
operations for turning on and off switches. Figs. 9E, 9F,
9G, and 9H are waveform diagrams illustrating current
flowing through coils.
Fig. 10 is a connection diagram illustrating a third
example of the inter-module balance adjustment circuit.
Fig. 11 is a connection diagram illustrating a fourth
example of the inter-module balance adjustment circuit.
Fig. 12 is a connection diagram illustrating a fifth
example of the inter-module balance adjustment circuit.
Fig. 13 is a block diagram of an example of a power
reserve apparatus including a balance adjustment circuit in
the present disclosure.
Fig. 14 is a block diagram of an example of a control
unit provided for each power storage module in the present
disclosure .
Fig. 15 is a flowchart illustrating a first example of
a balance adjustment process in the present disclosure.
Fig. 16 is a schematic diagram illustrating changes in
the voltages of battery cells in the first example of the
balance adjustment process in the present disclosure.
Fig. 17 is a flowchart illustrating a second example of
the balance adjustment process in the present disclosure.
Fig. 18 is a schematic diagram illustrating changes in
the voltages of battery cells in the second example of the
balance adjustment process in the present disclosure and
changes in the voltages of battery cells in an example of a
passive balance adjustment process.
Fig. 19 is a schematic diagram illustrating changes in
the voltage of battery cells in another example of the
balance adjustment process in the present disclosure.
Fig. 20 is a block diagram of a first example of an
application example of a power storage system including an
inter-module balance circuit in the present disclosure.
Fig. 21 is a block diagram of a second example of an
application example of the power storage system including
the inter-module balance circuit in the present disclosure.
Description of Embodiments
Embodiments that will be described hereinafter are
preferable specific examples of the present disclosure and
various technologically preferable limitations are provided
therefor, but the scope of the present disclosure is not
limited to these embodiments in the following description
unless description for limiting the present disclosure is
specifically included.
"Power Reserve Apparatus"
When a large number of power storage elements, that is,
for example, battery cells, are used to generate high power,
a configuration is adopted in which a plurality of power
storage units (hereinafter referred to as the power storage
modules) are connected to one another and a control
apparatus is provided for the plurality of power storage
modules in common. Such a configuration is referred to as a
power reserve apparatus .
Each power storage module is a unit obtained by
combining a battery unit including a series connection of a
plurality of battery cells, that is, for example, lithiumion
secondary batteries, or a series connection of a
plurality of battery cells connected parallel to one another
(a battery block) and a module controller provided for each
module. Each module controller is connected to an overall
control apparatus (hereinafter referred to as the control
box as necessary) , and the control box executes charge
control, discharge control, control for suppressing
deterioration, and the like. The module controllers and the
control box are configured by microcomputers.
The module controller for each power storage module and
the control box are connected to each other by a bus . As
the bus, a serial interface is used. As the serial
interface, more specifically, an SM bus (System Management
Bus) , a CAN (Controller Area Network) , an SPI (Serial
Peripheral Interface) , or the like is used.
Each module controller and the control box communicate
with each other. That is, information regarding the
internal state of each power storage module, that is,
battery information including information regarding the
voltage of each battery cell and the voltage of the entirety
of the module, information regarding current, and
information regarding temperature, is transmitted from each
module controller to the control box, in order to control a
charging process and a discharging process of each power
storage module .
Fig. 1 illustrates an example of a specific connection
configuration of the power reserve apparatus. For example,
four power storage modules MODI to M0D4 are connected in
series with one another. In this case, for example, a
positive terminal 1 (VB+) and a negative terminal 2 (VB-)
obtain the overall output voltage of the power reserve
apparatus, namely, for example, about 200 V . The power
storage modules include module controllers CNTl to CNT4 and
battery units BB1 to BB4 , respectively, in each of which a
plurality of parallel connections of a plurality of battery
cells or a plurality of battery blocks are connected to one
another .
The module controllers CNTl to CNT4 are connected to
one another through buses, and a communication terminal of
the module controller CNT4 is connected to a control box
ICNT. Battery information regarding the voltage of each
module and the like is transmitted from each module
controller to the control box ICNT. The control box ICNT
also includes a communication terminal 3 , so that
communication with the outside can be performed.
In an embodiment of the present disclosure, inter-cell
balance adjustment in each module is performed using passive
balance adjustment, and inter-module balance adjustment is
performed using active balance adjustment. Since inter-cell
voltage adjustment (referred to as the inter-cell balance
adjustment) is performed using the passive balance
adjustment, the sizes of circuits and circuit boards can be
reduced without requiring inductor elements. On the other
hand, since inter-module voltage adjustment (referred to as
the inter-module balance adjustment) is performed using the
active balance adjustment, it is possible to prevent the
overall voltage from decreasing. By combining the intercell
balance adjustment and the inter-module balance
adjustment, the time taken to complete the balance
adjustment can be reduced.
"Cell Balance"
In the present disclosure, by performing the inter
module balance adjustment on the above-described plurality
of power storage modules MODI to MODn, the output voltages
of the power storage modules are equalized. In general,
because a large number of battery cells are included in each
power storage module, variation between the power storage
modules is large compared to voltage balance between the
battery cells in each power storage module. Therefore, even
if the inter-cell balance adjustment in each power storage
module is to be performed, the inter-module balance
adjustment is still significant in reducing the time taken
to complete the balance adjustment.
Before describing the present disclosure, general
passive balance adjustment will be described. As
illustrated in Fig. 2A, for example, inter-cell balance
adjustment for sixteen battery cells CI to C16 will be
examined. A switch S16 for short-circuiting both ends of a
cell and a resistor R16 are connected to each cell. In Fig.
2A, only the switch S16 and the resistor R16 for the battery
cell C16 are illustrated for the purpose of simplification.
Turning on and off of the switches is controlled by, for
example, a controller CN . The controller CNT detects the
voltage of each cell.
When any of the battery cells has reached an upper
limit of working voltage during charging of the battery
cells CI to C16 that are discharging, the discharging ends.
As illustrated in Fig. 2B, in this state, the voltages of
the other battery cells are lower than the upper limit of
the working voltage. For example, differences in the amount
of self -discharge result in variation in the amount of
discharge between the battery cells. As illustrated in Fig.
2C, the controllers CNT turn on the switches of the battery
cells other than the battery cell C13, whose voltage is the
lowest, so that these battery cells discharge through the
respective resistors and the voltages of these battery cells
match the voltage of C13 .
Thereafter, the battery cells CI to C16 are charged
again until the voltage of any of the battery cells CI to
C16 reaches the upper limit of the working voltage. The
battery cells then discharge such that the voltages thereof
match the lowest voltage at a time when the upper limit of
the working voltage has been reached. By repeating such an
operation, it is possible to increase the voltages of the
battery cells CI to C16 in such a way as to be substantially
equal to the upper limit of the working voltage as
illustrated in Fig. 2D, thereby preventing a decrease in the
amount of discharge. The passive balance adjustment has a
simple configuration, but there is a problem in that energy
is discharged in vain.
Next, the active balance adjustment will be described
with reference to Fig. 3 . In the present disclosure,
flyback transformers Tl to T16 are connected to the battery
cells, respectively, as illustrated in Fig. 3A. The flyback
transformers Tl to T16 are configured by primary-side coils
l to 16 , secondary- side coils WOl to W016, and magnetic
cores, respectively. The primary-side coils Wl to W16 and
switches SI to S16 are connected in series with each other,
and the secondary-side coils WOl to W016 and switches SOI to
S016 are connected in series with each other. In Fig. 3A,
the flyback transformers Tl and T16, the switches SI and S16,
and the switches SOI and S016 for the battery cells CI and
C16, respectively, are illustrated.
In each of the flyback transformers Tl to T16, the
winding ratio of the primary-side coil to the secondary- side
coil has a certain value and the phase on the primary side
is opposite to that on the secondary side. Furthermore, the
flyback transformers Tl to T16 can transmit power in both
directions. Therefore, denotation of the primary side and
the secondary side is just for convenience, and both the
transmission of power from the primary side to the secondary
side and the transmission of power from the secondary side
to the primary side are possible.
The switches SI to S16 and the switches SOI to S016 are
independently controlled by the controller CNT. By
controlling the turning on and off of these switches, it is
possible to transmit energy obtained from a desired battery
cell to another battery cell. The controller CNT detects
the voltage of each cell.
When any of the battery cells has reached the upper
limit of the working voltage during charging of the battery
cells CI to C16 that are discharging, the discharging ends.
As illustrated in Fig. 3B, in this state, the voltages of
the other battery cells are lower than the upper limit of
the working voltage. For example, differences in the amount
of self -discharge result in variation in the amount of
discharge between the battery cells.
As illustrated in Fig. 3C, power is transmitted from
the battery cell C15, whose amount of power is the largest
(highest potential) when the upper limit of the working
voltage has been reached, to the battery cell C13 , whose
amount of power is the smallest (lowest potential) . As a
result, as illustrated in Fig. 3D, the remaining amounts of
power become substantially equal t one another. Thereafter,
by charging the battery cells CI to C16, all the battery
cells can be charged substantially up to a full charge
voltage. In practice, a plurality of processes are
performed. Such control is referred to as the active
balance adjustment. In comparison with the passive balance
adjustment, the active balance adjustment can use the
amounts of power effectively, which is preferable.
In the present disclosure, the above -described passive
balance adjustment is applied to the inter-cell balance
adjustment. As described above, the configuration of the
inter-cell balance adjustment is a configuration in which
the resistors and the switches are controlled in parallel
with the battery cells to control the turning on and off of
the switches. Furthermore, in the present disclosure, the
active balance adjustment is applied to the inter-module
balance adjustment.
Some examples of the configuration of the inter-module
balance adjustment that can be used for the present
disclosure will be described hereinafter.
Fig. 4 illustrates a circuit configuration in which an
existing cell balance circuit is directly applied to an
active inter-module balance adjustment circuit. For example,
balance control is performed between fourteen power storage
modules. Battery units BB1 to BB14 are connected in series
with one another. Each battery unit has a configuration in
which eight battery cells are connected parallel to one
another and sixteen parallel connections (battery blocks)
each including the eight battery cells are connected in
series with one another (so-called (8P16S) ). For example,
each battery unit generates a voltage of (3.2 V x 16 = 51.2
V ) . Therefore, the series connection of the fourteen
battery units BBl to BB14 generates a voltage of (51.2 V x
14 = 716 .8 V ) .
The positive side and the negative side of the series
connection of the fourteen battery units are connected to
both ends, respectively, of a secondary- side coil WO.
Furthermore, a common magnetic core M is provided.
Furthermore, a secondary- side switch SO is connected in
series with the secondary- side coil WO, and primary-side
switches SI to S14 are connected in series with primary-side
coils Wl to W14, respectively. The switches SO to S14 are,
for example, configured by MOSFETs .
In an active balance adjustment operation using the
configuration illustrated in Fig. 4 , the switch connected to
the primary- side coil of a battery unit whose voltage is the
highest is turned on, and then the switch is turned off
while the switch SO is turned on to supply current to the
secondary-side coil W O and charge the battery units BBl to
BB14 . For example, when the voltage of the battery unit BB2
is 56.5 V and the voltages of the other battery units are
55.9 V , the primary-side switch S2 is turned on for a
certain period of time, and then the switch S2 is turned off
while the secondary- side switch SO is turned on. The
battery units BB1 to BB14 (however, BB2 is excluded) are
charged by the current flowing through the secondary- side
coil WO.
In the configuration illustrated in Fig. 4 , since the
magnetic core M of transformers is used in common, it is
difficult to configure a plurality of, namely, for example,
fourteen, power storage modules, by storing the power
storage modules in different cases. In this case, a
transformer unit configured by the magnetic core, the coils,
and the switches is stored in a different case from the
fourteen power storage modules to configure a transformer
apparatus, and the fourteen power storage modules are
connected to the transformer apparatus in a star shape
having the transformer apparatus as its center. Such a
star- shaped configuration has a problem in that star- shaped
wiring becomes complex when the number of power storage
modules is large.
Furthermore, in the configuration illustrated in Fig. 4 ,
a voltage of 716.8 V is applied to the series circuit
including the secondary- side coil W O and the switch SO by
the fourteen battery units connected in series with one
another. Because withstand voltage required in practical
use is considered to be three times as large as applied
voltage, the withstand voltage of a semiconductor switch
element that configures the switch SO, such as an FET, is
supposed to be 2000 V or more. The configuration
illustrated in Fig. 4 , which requires a semiconductor switch
element having such a withstand voltage, is difficult to
realize. Therefore, the circuit configuration illustrated
in Fig. 4 can be used for the inter-module balance
adjustment, but this configuration is not preferable.
Fig. 5 illustrates a first example of an inter-module
balance adjustment circuit. As illustrated in Fig. 5 , the
magnetic core M is divided into fourteen magnetic cores Ml
to M14, and the secondary- side coil W 0 is divided into
fourteen secondary- side coils W01 to W014. In doing so, the
fourteen power storage modules can be separated and stored
in cases. In the configuration illustrated in Fig. 5 , a
voltage of 716.8 V is applied to each of the primary-side
switches S01 to S014. However, in the configuration
illustrated in Fig. 5 , flyback transformers Tl to T14 are
configured separately, and the primary- side and secondaryside
switches can independently control switching operations
since the primary- side and secondary- side switches are
connected to the respective coils. Therefore, as will be
described later, it is possible to perform control in such a
way as to obtain power from the plurality of battery units
at the same time and to supply power to the plurality of
battery units at the same time. Furthermore, by controlling
the lengths of the on periods in the switching operations,
the amounts of power can be controlled.
Fig. 6 illustrates a second example of the inter-module
balance adjustment circuit. As illustrated in Fig. 6 , in
the present disclosure, a flyback transformer Tl is
configured by a primary-side coil Wl, a secondary- side coil
W01, and a magnetic coil Ml. The primary-side coil Wl and a
switch SI are connected in series with each other, and the
secondary-side coil W01 and a switch SOI are connected in
series with each other. Similarly, flyback transformers T2
to T14 are configured by primary-side coils W2 to W14,
secondary- side coils W02 to W014, and magnetic coils M2 to
M14, respectively. The primary-side coils W2 to W14 and
switches S2 to S14 are connected in series with each other.
The secondary- side coils W02 to W014 and switches S02 to
S014 are connected in series with each other.
The series circuit including the primary-side coil Wl
and the switch SI of the flyback transformer Tl is connected
to the positive side and the negative side of a battery unit
BB1 of a power storage module. The other series circuits
including the primary- side coils W2 to W14 and the switches
S2 to S14, respectively, are connected to the positive sides
and the negative sides of battery units BB2 to BB14,
respectively, of power storage modules.
A power storage element 51 is provided, and the power
storage element 51 generates a common power supply voltage
CV. The common power supply voltage CV is a voltage lower
than the total voltage of the series connection of the
battery units, namely 716.8 V . The common power supply
voltage CV is preferably set to be substantially equal to or
lower than one-third of the withstand voltage of the
secondary- side switches. For example, the common power
supply voltage CV is set to be substantially equal to the
unit voltage (51.2 V ) of the battery units. The potential
of the common power supply voltage CV is controlled in such
a way as to be a desired voltage without an overflow or
depletion by controlling the total discharge current and the
total charge current .
The power storage element 51 is a battery, a capacitor,
or the like. The power storage element 51 sets one common
power supply line CL+ to the common power supply voltage CV
and another common power supply line CL- to 0 V . The other
common power supply line CL- is supposed to be a power
supply that is different from, and is not connected to, a
power supply (V-) of the series connection of the battery
units of the plurality of power supply modules. However,
the common power supply line CL- may be connected to the
power supply V - . One set of ends of the divided primaryside
coils 01 to W O14 is connected to the common power
supply line CL+ , and another set of ends of the divided
secondary- side coils 01 to 014 is connected to the common
power supply line CL- through the switches SOI to S014,
respectively.
The switches SO to S14 and the switches SOI to S014 are,
for example, configured by MOSFETs. As illustrated in Fig.
7 , for example, the switch SOI of the flyback transformer Tl
is configured by a MOSFET Q01 and a diode D01 connected
between the drain and the source of the MOSFET Q01, and the
switch SI is configured by a MOSFET Ql and a diode D l
connected between the drain and the source of the MOSFET Ql .
The turning on and off of the switches is controlled by
control signals from a control unit in the control box ICNT.
The control box ICNT receives information regarding results
of monitoring of voltage from the module controller CNT of
each power storage module and generates a control signal
(pulse signal) .
Alternatively, a semiconductor switch element such as
an IGBT (Insulated Gate Bipolar Transistor) may be used
instead of the MOSFET. It is to be noted that, in a switch
(configured by a MOSFET and a diode connected between the
drain and the source of the MOSFET) , current flowing from
the source to the drain automatically flows through the
diode without a control signal (automatic turning on of the
switch) .
The common power supply voltage CV is applied to the
series circuits of the secondary- side coils WOl to W014 and
the switches SOI to S014. For example, by setting the
common power supply voltage CV to the same voltage (51.2 V )
as the voltage applied to the primary- side coils and the
switches, the withstand voltage of the secondary- side
switches SOI to S014 can be set to about 154 V . Such a
value of withstand voltage is not very high for
semiconductor switches that configure the secondary- side
switches SOI to S014, and it becomes easier to configure the
inter-module balance adjustment circuit.
In each of the flyback transformers Tl to T14 , the
winding ratio of the primary-side coil to the secondary- side
coil is not limited to 1 , and the phase on the primary side
is opposite to that on the secondary side. Furthermore, the
flyback transformers Tl to T14 can transmit power in both
directions. Therefore, denotation of the primary side and
the secondary side is just for convenience, and both the
transmission of power from the primary side to the secondary
side and the transmission of power from the secondary side
to the primary side are possible.
To take the flyback transformer Tl as an example, when
the switch SI has been turned on after the switches SI and
SOI are off, current flows through the coil W l and the
magnetic core Ml is magnetized. While the switch SI is on,
current that increases over time flows through the coil W .
Next, when the switch SI has been turned off and the switch
SOI has been turned on, current flows to the coil W01
through the switch SOI since the magnetic core has been
magnetized. The current becomes current that decreases over
time. This holds true for the operation of the other
flyback transformers. The flyback transformers have a
function of a coupled inductor.
In an active balance adjustment operation using the
configuration illustrated in Fig. 6 , power is transmitted
from a battery unit whose voltage is the highest to the
power storage element 51 by controlling the primary- side
switches. Furthermore, by controlling the secondary- side
switches, power is transmitted to the battery unit of a
power storage module whose voltage is the lowest. Thus, the
inter-module balance adjustment circuit in the present
disclosure transmits power through two bidirectional flyback
transformers .
For example, an operation will be described when the
voltage of the battery unit BB3 is the highest, namely 56.5
V , and the voltage o f the battery unit BB2 is the lowest,
namely, 55.9 V . First, the switch S3 of the flyback
transformer T3 is turned on, and current flows through the
primary- side coil W3 using the battery unit BB3. as a power
supply. Next, the switch S3 is turned off, and the switch
S03 is turned on. Electromagnetic energy causes current to
flow through the secondary- side coil W03 and charges the
power storage element 51.
Next, the switch S03 is turned off while the switch S02
of the flyback transformer T2 is turned on, and the power
storage element 51 causes current to flow through the
secondary- side coil 02 . Next, the switch S02 is turned off
while the switch S2 is turned on, and current flowing
through the primary- side coil 2 charges the battery unit
BB2 . Thus, the active balance adjustment operation is
completed.
The active balance adjustment operation will be
described in a more detailed manner with reference to Figs.
8 and 9 . As illustrated in Fig. 8 , current flowing through
the coil W3 of the flyback transformer T3 is denoted by il,
and current flowing through the coil 03 is denoted by i2 .
The currents il and i2 have opposite phases. Current
flowing through the coil 02 of the flyback transformer T2
is denoted by i3, and current flowing through the coil 2 is
denoted by i . The currents i3 and i4 have opposite phases.
Furthermore, assume that the power storage element 51 has
been fully charged at the time of the beginning of the
operation.
As illustrated by a timing chart of Fig. 9 ,
transmission of power through the flyback transformer T3 and
transmission of power through the flyback transformer T2 are
performed in parallel with each other. First, as
illustrated in Figs. 9A and 9C, the switches S3 and S02 are
turned on for the same period of time. When the switch S3
has been turned on, the current il that gradually increases
flows through the coil W3 as illustrated in Fig. 9E. When
the switch S02 has been turned on, the current i3 that
gradually increases flows through the coil W02 as
illustrated in Fig. 9G. The current i3 flows through the
power storage element 51 in a discharging direction.
Next, the switches S3 and S02 are turned off, and the
switches S03 and S2 are turned on for the same period of
time as illustrated in Figs. 9B and 9D. When the switch S03
has been turned on, the current i2 that gradually decreases
flows through the coil W03 as illustrated in Fig. 9F. The
current i2 flows through the power storage element 51 in a
charging direction. By charging the power storage element
51 using the current i2, power is transmitted from the
battery unit BB3 to the power storage element 51.
When the switch S2 has been turned on, the current i4
that gradually decreases flows through the coil W2 as
illustrated in Fig. 9H. The current i4 flows in a direction
in which the battery unit BB2 is charged. The charging
using the current i4 causes power in the power storage
element 51 to be transmitted to the battery unit BB2 . It is
to be noted that, in actual transmission of power, power is
transmitted little by little not by a single switching
operation but by a plurality of switching operations.
Furthermore, the amounts of power to be transmitted can be
set to desired values by modulating the pulse widths of the
pulse signals for the switches and by controlling the on
periods of the switches. In addition, although the switches
S3 and S02 are synchronized with each other in Fig. 9 , the
synchronizing relationship need not be established in
practice if the common power supply voltage CV allows a
certain width.
Furthermore, a modification of the inter-module balance
adjustment circuit that can be applied to the present
disclosure will be described. In the above-described inter
module balance adjustment circuit, power obtained through a
single flyback transformer is transmitted through a single
flyback transformer. However, power may be obtained through
a plurality of flyback transformers. For example, power may
be obtained through a power storage module whose voltage is
the highest and a power storage module whose voltage is the
second highest. Furthermore, the obtained power may be
transmitted through a plurality of flyback transformers.
For example, power may be supplied to a power storage module
whose voltage is the lowest and a power storage module whose
voltage is the second lowest. For example, in the above -
described configuration illustrated in Fig. 6 , power is
obtained through the flyback transformer T14 using small
current, and, at the same time, power is obtained through
the flyback transformer T3 using large current. Furthermore,
at the same time as the obtainment of the power, power is
supplied through the flyback transformers Tl and T2 using
moderate current .
As illustrated in Fig. 10, on the secondary side of the
flyback transformers Tl to T14 of the power storage modules,
capacitors CP1 to CP14, respectively, are inserted between
the common power supply line CL+ and the common power supply
line CL- . By decreasing high-frequency components using the
capacitors CP1 to CP14, voltage generated in the common
power supply lines CL+ and CL- can be output as a directcurrent
power supply. The direct -current power supply may
be supplied as the power supply of the control box ICNT.
Furthermore, as illustrated in Fig. 11, a flyback
transformer Tx may be provided for all the power storage
modules in common. The flyback transformer Tx is configured
by a primary-side coil y , a secondary- side coil Wx, and a
magnetic core. The coil Wx and a switch Sx are connected in
series with each other. The coil Wy and a switch Sy are
connected in series with each other. One end of the
secondary- side coil Wx of the flyback transformer Tx is
connected to a terminal 52, and another end is connected to
a line of 0 V through the switch Sx. The terminal 52 is
connected to a common power supply voltage CV terminal.
One end of the primary- side coil Wy is connected, for
example, to the positive side (V+) of the series connection
of the battery units BB1 to BB14 of a plurality of, namely,
for example, fourteen, power storage modules. Another end
of the primary-side coil Wy is connected to the negative
side (V-) of the series connection of the battery units BB1
to BB14 . As with the configuration illustrated in Fig. 6 ,
the flyback transformers Tl to T14 and the power storage
element 51 are connected to the battery units BB1 to BB14,
and the above-described inter-module balance control is
performed .
According to the configuration illustrated in Fig. 11,
power can be supplied to the battery units of all the power
storage modules at once through the flyback transformer Tx,
and therefore it is possible to increase the number of
variations of the operation of the inter-module balance
control .
Furthermore, in the present disclosure, a forward
converter adopting a method other than a flyback converter
method and a power transmission apparatus adopting an
electromagnetic coupling method such as an RCC (Ringing
Choke Converter) method may be used.
Fig. 12 illustrates an application example of the
present disclosure, in which another power reserve apparatus
configured by power storage modules MOD101 to MOD104 is
connected to power storage modules MODI to MOD14 (the
configuration illustrated in Fig. 6 ) . The common power
supply lines CL+ and CL- can be connected to the other power
reserve apparatus insofar as the common power supply voltage
CV is the same between the two power reserve apparatuses.
That is, it is easier to increase the number of power
storage modules connected.
"Benefits of Inter-module Balance Adjustment Circuit"
In the inter-module balance adjustment circuits having
the configurations illustrated in Figs. 5 , 6 , 10, 11, and 12,
since the flyback transformer of each module is configured
separately, star-shaped wiring need not be provided unlike
the configuration in which a magnetic core is used in common,
and therefore wiring can be simple.
Furthermore, in these inter-module balance adjustment
circuits, the voltage of both ends of the battery unit of
each power storage module is applied to the primary-side
coil and the switch of each flyback transformer, and the
common power supply voltage CV is applied to the secondaryside
coil and the switch. The common power supply voltage
CV is, for example, configured to have the same value as the
voltage of both ends of the battery unit of each power
storage module. Therefore, the voltage of the series
connection of all the power storage modules is not applied
to the coils and the switches, and therefore coils and
switches having low withstand voltages can be used, which is
advantageous .
Furthermore, in these inter-module balance adjustment
circuits, the primary-side switches SI to S14 and the
secondary- side switches SOI to S014 of the flyback
transformers can be controlled using independent control
pulse signals. Therefore, power can be transmitted through
a plurality of desired flyback transformers. Furthermore,
by setting the lengths of the on periods of the switching
operations, the amounts of power to be transmitted through
the flyback transformers can be individually controlled.
That is, by prolonging the period for which a switch is
turned on in accordance with the amount of power to be
transmitted, the amount of power to be transmitted can be
changed .
Furthermore, since large current flows between output
terminals V+ and V - of the plurality of power storage
modules, relatively large noise tends to be generated.
However, since the common power supply voltage CV is
insulated from the output terminals V+ and V-, effects of
noise caused by variation in load current can be reduced.
The common power supply voltage CV, which is hardly
affected by noise, can be used as the power supply of the
control box ICNT. For example, the value of the common
power supply voltage CV may be the same (+5 V , +12 V , or the
like) as the value of the power supply voltage of the
control unit. When the common power supply voltage CV is
used as the power supply of the control box ICNT, the power
supply of the control box ICNT can be configured in such a
way as not to be affected by variation in the voltages of
the power storage modules.
"Example of Power Reserve System"
Fig. 13 illustrates a configuration in which the
present disclosure is applied to a power reserve system
including n , namely, for example, three, power storage
modules MODI to MOD3 . The power storage modules include
battery units BB1, BB2 , and BB3 , the above-described intercell
balance adjustment units and inter-module balance
adjustment units, battery monitoring units 61, 62, and 63
(represented as BMU1, BMU2 , and BMU3 in the figure), and
control units 71, 72, and 73 (represented as MCUl, MCU2 , and
MCU3 in the figure) , respectively. In addition, the battery
monitoring units 61, 62, and 63 and the control units 71, 72,
and 73 are connected to each other by communication paths
that enable interactive communication.
The inter-cell balance adjustment units, the inter
module balance adjustment units, the battery monitoring
units 61, 62, and 63, and the control units 71, 72, and 73
configure the module controller CNT illustrated in Fig. 1 .
The control units 71, 72, and 73 of the modules and the
control box ICNT that controls the entirety of the system
are connected with each other through communication paths
that enable interactive communication. As a communication
method, for example, CAN is used. In these years, the CAN
is used as an on-vehicle LAN. It is to be noted that Fig.
13 illustrates the configuration for controlling the intercell
balance adjustment and the inter-module balance
adjustment, and therefore connections relating to
transmission of power are omitted.
The inter-cell balance adjustment units equalize the
voltages of the battery blocks (or the battery cells) of the
battery units of the power storage modules using the passive
balance adjustment method. Since a battery block whose
voltage is high is caused to discharge in the passive
balance adjustment method, switches and resistors are
connected parallel to the battery blocks. The switches are,
for example, configured by MOSFETs (Metal Oxide
Semiconductor Field Effect Transistors). Switches Fll, F12,
and F13 are connected to the power storage module MODI,
switches F21, F22, and F23 are connected to the power
storage module M0D2 , and switches F31, F32 , and F33 are
connected to the power storage module MOD3 .
For the inter-module balance adjustment units, any of
the above-described configurations of the inter-module
balance adjustment circuit may be used. In the
configuration illustrated in Fig. 13, for example, the
configuration illustrated in Fig. 6 is used. That is,
flyback transformers Tl, T2 , and T3 are provided, battery
units and switches SI, S2 , and S3 are connected to the
primary side of the flyback transformers, and switches SOI,
S02, and S03 and a power storage element 51 are connected to
the secondary side of the flyback transformers.
Control signals for controlling the switches included
in the balance adjustment units are output from the control
units 71, 72, and 73. The control signals for controlling
the switches included in the inter-cell balance adjustment
units of the power storage modules are output from the
control units of the power storage modules. For example, in
the power storage module MODI, the voltage of each battery
block of the battery unit BB1 is detected by the battery
monitoring unit 61 and transmitted to the control unit 71.
The control unit 71 detects a battery block whose voltage is
the highest among the voltages of the battery blocks and
turns on the switch connected to the battery block, so that
the battery block discharges. The same inter-cell balance
adjustment operation is performed in the other power storage
modules MOD2 and MOD3 . Since the amounts of discharge
correspond to the periods for which the switches are turned
on, the pulse widths of the control signals for controlling
the switches have been modulated in accordance with the
amounts of discharge.
Control information for the inter-module balance
adjustment is generated by the control box ICNT, and
transmitted to the control unit of each power storage module.
That is, the voltages of all the battery blocks of all the
power storage modules MODI, MOD2 , and MOD3 and the voltages
of the battery units are transmitted to the control box ICNT
through the battery monitoring units 61, 62, and 63, the
control units 71, 72, and 73, and the communication paths.
The control box ICNT generates the control information for
the inter-module balance adjustment from the received
voltage information and transmits the control information to
the power storage modules. Since the amounts of energy to
be transmitted between the power storage modules correspond
to the periods for which the switches are turned on, the
pulse widths of the control signals for controlling the
switches have been modulated in accordance with the amounts
of energy.
In parallel with the inter-cell balance adjustment
operation and the inter-module balance adjustment operation,
the control box ICNT measures the voltage between the power
supply lines CL+ and CL- to which the common power supply
voltage CV is supplied, and controls the entirety of the
inter-module balance adjustment such that the common power
supply voltage CV becomes a desired voltage.
Alternatively, the control information for the intercell
balance adjustment may be generated by the control
units 71, 72, and 73 and may be supplied to the switches
FF11 to FF33 through the battery monitoring units 61, 62,
and 63. Furthermore, the control information for the intercell
balance adjustment may be generated by the control box
ICNT and may be transmitted to the control units of the
power storage modules by communication.
"Example of Module Controller"
An example of the configuration of the module
controller, that is, for example, the battery monitoring
unit 61 and the control unit 71 of the power storage module
MODI, will be described with reference to Fig. 14. The
battery unit BB1 is, for example, configured by the series
connection of three battery cells CI, C2 , and C3 . Switches
Fll, F12, and F13 configured by FETs and resistors are
connected parallel to the battery cells. The switches Fll,
F12, and F13 are turned on or off by the control signals
from the control unit 71 whose pulse widths have been
modulated. As a result, the inter-cell balance adjustment
is completed by the passive balance adjustment.
The battery monitoring unit 61 includes a multiplexer
55. The voltages of the battery cells CI, C2 , and C3 and
the voltage of both ends of the battery unit BB1 are input
to the multiplexer 55. The multiplexer 55 sequentially
selects these voltages and supplies the voltages to an A/D
converter 65. The A/D converter 65 converts the individual
values of voltage into digital signals. For example, analog
voltage data is converted into digital voltage data of 14 to
18 bits.
A resistor 57 that detects current flowing through the
battery unit BB1 is connected in series with the battery
unit BB1. The voltage of both ends of the resistor 57 is
supplied to an A/D converter 67 through an amplifier 56.
The A/D converter 67 converts the values of current into
digital signals. Furthermore, a temperature measurement
unit 58 that detects the temperature of each cell is
provided. Temperature information from the temperature
measurement unit 58 is supplied to an A/D converter 66. The
A/D converter 66 converts the temperature information into a
digital signal. It is to be noted that, as methods used by
the A/D converters 65, 66, and 67, various methods such as a
successive-approximation method and a DS (delta-sigma)
method can used. Furthermore, A/D converters need not
necessarily be provided separately for voltage, current, and
temperature .
The outputs of the A/D converters 65, 66, and 67 are
supplied to a communication unit 68. The communication unit
68 communicates with the control unit 71. Furthermore, the
control unit 71 is connected through a communication path to
the control box ICNT that controls the entirety of the
system. In Fig. 14, the configuration relating to the
inter-module balance adjustment is omitted. The control
unit 71 generates control signals for controlling the
switches of the inter-module balance adjustment units.
In the module controller CNT illustrated in Fig. 14,
the A/D converters 65, 66, and 67, the communication unit 68,
and the control unit 71 are low voltage power supply units
that can operate using low voltage, namely, for example, a
power supply of 5 V . The power supply of the low voltage
power supply units is configured to be supplied from the
control box ICNT. When the power supply is supplied from
the battery unit BB1, the balance between the power storage
modules can be lost due to differences in power consumption
between the module controllers. Therefore, the power supply
of the low voltage power supply units in the module
controller is configured to be supplied from the control box
ICNT.
Although the module controller of the power storage
module MODI has been described above, module controllers of
the other power storage modules M0D2 and MOD3 have the same
configuration as the module controller of the power storage
module MODI .
"First Example of Balance Adjustment in Present Disclosure"
Fig. 15 illustrates the flow of the control operation
of balance adjustment according to an embodiment of the
present disclosure during charging. Furthermore, Fig. 16
illustrates changes in the voltages of battery cells
included in power storage modules during charging. As
illustrated in Fig. 13, the illustrated changes in voltage
are changes in the voltages of battery cells in the case of
a power reserve system including three power storage modules
MODI, MOD2, and MOD3 , each including three battery cells.
In Fig. 16, changes in voltage indicated by dash-dot
lines represent changes in the voltages (hereinafter
referred to as the cell voltages as necessary) of the three
battery cells in the power storage module MODI, changes in
voltage indicated by solid lines represent changes in the
cell voltages of the three battery cells in the power
storage module MOD2 , and changes in voltage indicated by
broken lines represent changes in the cell voltages of the
three battery cells in the power storage module M0D3 . By
the control in the present disclosure, all the cell voltages
eventually become substantially the same, and the voltages
between the power storage modules become substantially the
same. For example, differences Dn in voltage between the
battery cells fall within a control completion voltage width
indicated by Vend in Fig. 16. For example, Vend = 30 mV.
As illustrated in Fig. 16, the period from time to, at
which charging begins, to when the differences Dn in voltage
between the battery cells in the battery units have fallen
within the voltage width Vend is divided in accordance with
processes, as will be described later. The processes switch
in accordance with the relationship between first, second,
third, and fourth threshold values (voltages) VI, V2 , V3 , V ,
and V5 (VI > V2 > V3 > V4 > V5) and the cell voltages. The
threshold value V I corresponds to an upper limit value of
the cell voltages during charging. The threshold values V2
and V 3 are an upper limit value and a lower limit value,
respectively, of the voltage width Vend. The threshold vale
V5 is used to judge whether or not to perform preliminary
charging. The threshold value V4 relates to a second
example of the balance adjustment, which will be described
later.
In the example illustrated in Fig. 16, the processes
switch in accordance with the threshold values V I to V5 as
described below. It is to be noted that charging already
begins at the time to.
Time to to tl: Inter-cell balance adjustment (passive
balance adjustment) period
Time tl to t2 : Inter-module balance adjustment (active
balance adjustment) period
Time t2 to t3 : Inter-cell balance adjustment (passive
balance adjustment) period
Time t3 to t4 : Inter-cell balance adjustment and inter
module balance adjustment period
Furthermore, the flow of the processes will be
described with reference to a flowchart of Fig. 15. The
definitions of signs illustrated in the flowchart of Fig. 15
are as follows .-
Vcell Nn: The n-th cell voltage of the N-th power
storage module (in the example illustrated in Fig. 16, N = 1
to 3 and n = 1 to 3 )
Vcell Nmax: The maximum cell voltage in the N-th power
storage module
Vcell max: The maximum cell voltage in all the batterycells
Vend: The balance control completion voltage width
Charging continues (step SI) after the beginning of the
charging, and, in step S2, whether or not the individual
cell voltages Vcell Nn of all the battery cells are higher
than the threshold value V5 is judged. The control box ICNT
monitors each of the cell voltages of the nine battery cells
and each of the voltages of the three power storage modules.
If the cell voltages Vcell Nn are equal to or lower
than V5, preliminary charging is performed in step S3 using,
for example, a current of 0.1 C . If it is judged that the
cell voltages Vcell Nn are higher than V5 , the charging
continues (step S4) , and a judgment process in step S5 is
performed.
If the battery cells are lithium- ion secondary
batteries, constant-current/constant-voltage charging is
performed. For example, charging is performed using a
charging current of 0.5 C , and, as illustrated in Fig. 16,
the cell voltages increase because of the charging that
began at the time to.
In step S5, using the threshold values V2 and V3 ,
whether or not a condition (V2 < cell voltages Vcell Nn <
V3) is satisfied and whether or not the differences
(variations) Dn between all the cell voltages satisfy (Dn <
Vend) are judged. That is, whether or not all the cell
voltages exist within the voltage width between the
threshold value V2 (upper limit value) and the threshold
value V 3 (lower limit value) is judged. If results of the
judgment are positive, the operation of charging control
(also the operation of balance control) ends (step S6) . It
is to be noted that, as with the normal charging control,
the charging may be terminated by detecting full charge.
If the results of the judgment in step S5 are negative,
processes in step S7 and step S8 are performed. Step S7 is
a process for judging whether or not any of the cell
voltages Vcell Nn has exceeded the threshold value V3 . Step
S8 is a process for judging whether or not any of the cell
voltages Vcell Nn has exceeded the threshold value VI. Step
S7 is a process for judging whether or not to perform the
inter-cell balance adjustment, and step S8 is a process for
judging whether or not to perform the inter-module balance
adjustment .
If a result of the judgment in step S7 is positive,
that is, if the voltage of the battery cell has exceeded the
threshold value V3 , the battery cell discharges and the
inter-cell balance adjustment operation begins (step S9) .
If the result of the judgment in step S7 is negative, the
control returns to step S , and the same control as that
described above is repeated. When the inter- cell balance
adjustment has begun in step S9, too, the control returns to
step S , and the same control as that described above is
repeated. If the result of the judgment in step S8 is
negative, too, the control returns to step S4 , and the same
control as that described above is repeated.
In the example illustrated in Fig. 16, at the timing to,
the maximum cell voltage of the power storage module MODI
(having the changes in voltage indicated by the dash-dot
lines) is equal to or higher than the threshold value V 3 .
Therefore, at the timing to, the battery cell whose voltage
is the highest among the three battery cells in the power
storage module MODI has already begun to discharge. However,
since the charging operation is continuing and the charge
current is larger than the discharge current during the
inter-cell balance adjustment, the voltage of a battery cell
that discharges during the inter-cell balance adjustment
increases. The voltage of the battery cell during the
discharging increases more gradually than the voltages of
the other battery cells in the same module. Furthermore,
because another battery cell whose voltage is the second
highest in the power storage module MODI reaches the
threshold value V 3 at a time later than the timing to, this
battery cell also begins to discharge and therefore the
inclination of an increase in voltage becomes more gradual
after a certain moment. Thus, in the inter-cell balance
adjustment, a cell discharge FET is turned on to
intentionally delay the discharging, thereby keeping the
balance of voltage with the other power storage modules .
In the case of the power storage module MOD3 (having
the changes in voltage indicated by the broken lines) , too,
a battery cell whose cell voltage has reached the threshold
value V 3 discharges at the timing to. In the case of the
power storage module MOD2 (having the changes in voltage
indicated by the solid lines) , because the cell voltages of
all the battery cells do not reach the threshold value V3
between the timing t o and the timing tl, the inter-cell
balanqe adjustment operation (discharging by the cells) is
not performed.
If the result of the judgment in step S8 is positive,
that is, if the cell voltage of any of the battery cells
exceeds the threshold value VI, the control proceeds to step
S10, and the inter-module balance adjustment begins. In the
example illustrated in Fig. 16, the maximum cell voltage of
the power storage module MODI becomes equal to or higher
than the threshold value V I at the timing tl, and the inter
module balance adjustment begins at the timing tl.
In step Sll, Vcell max (the maximum cell voltage among
all the battery cells) is determined. Next, in step S12,
Vcell Nmax and the threshold value V2 are compared. That is,
in step S12, the judgment of (Vcell Nmax > V2) is made. If a
result of this judgment is negative, the control proceeds to
step S13 . In step S13, the voltage of the power storage
module (N) judged in step S12 is increased. The process
then proceeds to step S15.
In the example illustrated in Fig. 16, because Vcell
Nmax of the power storage module MOD2 (the changes in
voltage indicated by the solid lines) does not reach the
threshold value V2 before the timing t2, the voltage of the
power storage module M0D2 is increased by the inter-module
balance adjustment (step S13) . Since power is supplied from
the other power storage modules in the inter-module balance
adjustment, an increase in the changes of the voltage of the
power storage module MOD2 is sharper than an increase during
charging.
On the other hand, since Vcell Nmax of each of the
power storage modules MODI and MOD3 is equal to or higher
than the threshold value V2 , power is discharged and the
cell voltages of these power storage modules decrease in
step S14 . In step S15, whether or not the maximum cell
voltage Vcell max among all the battery cells is lower than
the threshold value V2 . At the timing t2 illustrated in Fig.
16, Vcell max is smaller than the threshold value V2 .
Therefore, the control proceeds to step S16, and the intermodule
balance adjustment ends.
In the inter-module balance adjustment, the control box
ICNT generates control signals whose pulse widths have been
modulated and supplies the control signals to the control
units 71 to 73 of the module controllers of the power
storage modules. The control units 71 to 73 control the
switches for the inter-module balance adjustment in
accordance with the control signals. When the voltages of
the power storage modules are to be decreased, the primaryside
of the flyback transformers discharges, and the
secondary side of the flyback transformers enters the
charging state. When the voltages of the power storage
modules are to be increased, the secondary side of the
flyback transformers discharges, and the primary side of the
flyback transformers enters the charging state.
After step S16, the control returns to step S . At the
timing t2 , because the differences in voltage between the
battery cells do not fall within the voltage width Vend, the
results of the judgment in step S5 are negative, and the
control proceeds to step S7 and step S8. At the time t2,
because (Vcell Nn > VI) is not satisfied, the inter-cell
balance adjustment is performed on a power storage module
for which the result of the judgment in step S7 is positive.
When the cell voltage has exceeded the threshold value
V3 between the timing t2 and the timing t3, the battery cell
discharges during the inter-cell balance adjustment, and, as
a result, the inclination of an increase in the cell voltage
becomes more gradual. Even if the inter-cell balance
adjustment is performed, since the charge current larger
than the discharge current is flowing, the inclination of a
change in the cell voltage is positive.
Next, at the timing t3, the cell voltages of all the
power storage modules fall within the voltage width defined
by the threshold values V I and V3 . Therefore, the result of
the judgment in step S7 becomes positive, and accordingly
the inter-cell balance adjustment is performed and the cell
voltages are controlled in such a way as to become close to
the threshold value V3 . Furthermore, because the maximum
cell voltage of the power storage module MODI reaches the
threshold value VI, the result of the judgment in step S8
becomes positive. By the control of the above -described
inter-module balance adjustment in step S10 to step S16, the
voltages of the power storage modules are controlled in such
a way as to become close to the threshold value V2 .
When the results of the judgment in step S5 have become
positive by such control, the cell voltages of all the
battery cells fall within the desired voltage width Vend,
and since all the batteries are within the range of V2 to V3 ,
the charging operation (balance control operation) ends.
"Second Example of Balance Adjustment in Present Disclosure"
A second example of the balance adjustment will be
described using a flowchart of Fig. 17 and a graph of Fig.
18 illustrating changes in voltage. In the second example,
as illustrated by broken lines in Fig. 18, if it is detected
in step S21 that the maximum cell voltage Vcell Nmax in the
third power storage module has decreased to the threshold
value V2 when the voltages of the battery cells decrease in
the period (tl to t2) of the inter-module balance adjustment,
the voltage of the power storage module is kept constant in
step S22. At this time, the threshold value V , which is
smaller than the threshold value VI, may be set separately
from the threshold value V2 , and the voltage of the power
storage module may be kept constant upon reaching the
threshold value V .
Next, in step S23, whether or not the maximum cell
voltage Vcell max among all the battery cells is lower than
the threshold value V2 is judged. If it is judged that the
maximum cell voltage Vcell max is lower than the threshold
value V2 , the inter-module balance adjustment ends (step
S24) . By such control, variation in voltage between the
battery cells at the timing t2 can be reduced.
In another example illustrated in Fig. 19, only the
inter-module balance adjustment is performed in advance in
the charging/discharging stop period (to to tl) , which is
prior to the timing tl at which the above-described control
begins, so that the variation in voltage between the battery
cells is reduced.
It is to be noted that the present disclosure can have
the following configurations.
(1)
A power reserve apparatus comprising:
a first module including:
a first set of battery cells; and
a first inter-cell balance adjustment unit
configured to use passive balancing to reduce voltage
variance among the first set of battery cells;
a second module including:
a second set of battery cells; and
a second inter-cell balance adjustment. unit
configured to use passive balancing to reduce voltage
variance among the second set of battery cells; and
an inter-module balance adjustment unit configured to
use active balancing to reduce voltage variance among the
first and second modules.
(2)
The power reserve apparatus of (1) , wherein:
the first module further includes a first battery
monitoring unit configured to detect voltages of each of the
battery cells within the first set; and
the second module further includes a second battery
monitoring unit configured to detect voltages of each of the
battery cells within the second set.
(3)
The power reserve apparatus according to any one of (1)
or (2) , wherein:
the first module further includes a first control unit
configured to determine which switches within the first
inter-cell balance adjustment unit are to be switched to
passively reduce voltage variance among the first set of
battery cells based on the voltages detected by the first
battery monitoring unit; and
the second module further includes a second control
unit configured to determine which switches within the
second inter-cell balance adjustment unit are to be switched
to passively reduce voltage variance among the second set of
battery cells based on the voltages detected by the second
battery monitoring unit .
(4)
The power reserve apparatus according to any one of (1) ,
(2) , and (3) , further comprising a battery controller
configured to:
receive a first cumulative voltage of the first set of
battery cells within the first module from the first control
unit ;
receive a second cumulative voltage of the second set
of battery cells within the second module from the second
control unit ; and
transmit control information to the first and second
modules indicating which switches of the inter-module
balance adjustment unit are to be switched to actively
reduce voltage variance among the first and second modules.
(5)
The power reserve apparatus according to any one of (1) ,
(2) , (3) , and (4) , wherein the battery controller and the
first and second modules are configured for each of the
battery cells, to stop charging a battery cell when the
battery cell reaches a first voltage threshold.
(6)
The power reserve apparatus according to any one of (1) ,
(2) , (3) , (4) , and (5) , wherein the battery controller and
the first and second modules are configured to reduce
variance among the battery cells until each of the voltages
of each of the battery cells are between a second voltage
threshold and a third voltage threshold.
(7)
The power reserve apparatus according to any one of (1) ,
(2) , (3) , (4) , (5) , and (6) , wherein a difference between
the second voltage threshold and the third voltage threshold
is approximately 30 millivolts.
(8)
The power reserve apparatus according to any one of (1) ,
(2), (3), (4), (5), (6), and (7), wherein the battery
controller and the first and second modules are configured
to perform preliminarily charging on any of the battery
cells that fall below a fourth voltage threshold.
(9)
The power reserve apparatus according to any one of (1) ,
(2), (3), (4), (5), (6), (7), and (8), wherein:
the first and second modules are configured to
passively reduce voltage variance using the respective first
and second inter-cell balance adjustment units during a
first time period, and
the battery controller is configured to actively reduce
voltage variance using the inter-module balance adjustment
unit during a second time period after the first time period.
(10)
The power reserve apparatus according to any one of (1) ,
(2), (3), (4), (5), (6), (7), (8) and (9), further
comprising a power storage element configured to store a
common power supply voltage that is substantially equal to a
voltage of the modules when fully charged.
(11)
The power reserve apparatus according to any one of (1),
(2), (3), (4), (5), (6), (7), (8), (9) and (10), wherein:
the first module includes:
a first primary-side coil electrically connected to
the power storage element and a first switch,
a first secondary-side coil electrically connected to
the first set of battery cells and a second switch, and
a first magnetic core inductively coupled to the first
primary-side coil and the first secondary-side coil; and
the second module includes :
a second primary-side coil electrically connected
to the power storage element and a third switch,
a second secondary- side coil electrically connected
to the second set of battery cells and a fourth switch, and
a second magnetic core inductively coupled to the
second primary-side coil and the second secondary- side coil.
(12)
The power reserve apparatus according to any one of (1) ,
(2), (3), (4), (5), (6), (7), (8), (9), (10), and (11),
wherein the battery controller is configured to indicate a
sequence in which the first, second, third, and fourth
switches are to be switched to actively reduce voltage
variance among the first and second modules.
(13)
The power reserve apparatus according to any one of (1),
(2), (3), (4), (5), (6), (7), (8), (9), (10), (11), and (12),
wherein the battery controller is configured to activate the
first switch for a time period then activate the second
switch for a second time period to charge the power storage
element to reduce a voltage of the first set of battery
cells when the first set of battery cells has a higher
voltage than the second set of battery cells.
(14)
The power reserve apparatus according to any one of (1) ,
(2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12),
and (13), wherein the battery controller is configured to
activate the fourth switch for a third time period then
activate the third switch for a fourth time period to
increase the voltage of the second set of battery cells.
(15)
A power reserve method comprising:
detecting voltages of a first set of battery cells in a
first module;
detecting voltages of a second set of battery cells in
a second module;
determining a first cumulative voltage of the first
module based on the voltages of the first set of battery
cells ;
determining a second cumulative voltage of the second
module based on the voltages of the second set of battery
cells ;
controlling a first group of switches to actively
balance the cumulative voltages among the first and second
modules; and
controlling a second group of switches to passively
balance voltages among the battery cells within the first
module and voltages among battery cells within the second
module .
(16)
The power reserve method according to (15) , wherein
actively balancing of the cumulative voltages of the first
and second set of modules occurs sequentially with passively
balancing the voltages among the battery cells within the
first module and the voltages among battery cells within the
second module .
(17)
The power reserve method according to any one of (15)
or (16) , further comprising charging the first and second
sets of battery cells.
(18)
The power reserve method according to any one of (15) ,
(16) , and (17) , wherein the first and second modules are
actively balanced after at least the voltage of one of the
battery cells within the first and second sets exceeds a
first voltage threshold.
(19)
The power reserve method according to any one of (15) ,
(16), (17), and (18), wherein active balancing includes:
determining a first maximum voltage of the battery
cells within the first set;
determining a second maximum voltage of the battery
cells within the first set;
transferring power from the first module to the second
module if the second maximum voltage is greater than a
second voltage threshold and the first maximum voltage is
less than the second voltage threshold; and
transferring power from the second module to the first
module if the first maximum voltage is greater than the
second voltage threshold and the second maximum voltage is
less than the second voltage threshold.
(20)
The power reserve method according to any one of (15) ,
(16) , (17) , (18) , and (19) , wherein active balancing of the
first and second sets of battery cells ends after the
voltages of all of the battery cells are less than the
second voltage threshold.
(21)
The power reserve method according to any one of (15) ,
(16) , (17) , (18) , (19) , and (20) , wherein passive balancing
is applied to each battery cell that exceeds a third
threshold during changing.
(22)
The power reserve method according to any one of (15) ,
(16), (17), (18), (19), (20), and (21), wherein the first
and second sets of battery cells are charged until the
voltages of first and second sets of battery cells are less
than the second threshold voltage, greater than a third
threshold voltage, and a variance between each of the
voltages of the battery cells is less than a fourth voltage
threshold.
(23)
The power reserve method according to any one of (15) ,
(16), (17), (18), (19), (20), (21), and (22), wherein the
fourth voltage threshold is approximately 30 millivolts.
(24)
An electric vehicle comprising:
a power reserve apparatus including:
a first module including:
a first set of battery cells; and
a first inter-cell balance adjustment unit
configured to use passive balancing to reduce voltage
variance among the first set of battery cells;
a second module including:
a second set of battery cells; and
a second inter-cell balance adjustment unit
configured to use passive balancing to reduce voltage
variance among the second set of battery cells; and
an inter-module balance adjustment unit configured
to use active balancing to reduce voltage variance among the
first and second modules; and
a conversion apparatus configured to use power
supplied from the power reserve apparatus to drive an engine
and power vehicle control electronics.
(25)
The electric vehicle of (24) , wherein the conversion
apparatus includes a motor.
(26)
The electric vehicle according to any one of (24) or
(25) , wherein the conversion apparatus stores regenerative
power to the power reserve apparatus from a rotational force
of braking at least one driving wheel .
(27)
The electric vehicle of according to any one of (24) ,
(25), and (26), further comprising a charging port to
receive power from an external power supply to charge the
first and second sets of battery cells using passive and
active balancing.
(28)
The electric vehicle according to any one of (24) , (25) ,
(26) , and (27) , wherein:
the first module further includes a first battery
monitoring unit configured to detect the voltages of each of
the battery cells within the first set; and
the second module further includes a second battery
monitoring unit configured to detect the voltages of each of
the battery cells within the second set.
(29)
The electric vehicle according to any one of (24) , (25) ,
(26) , (27) , and (28) , wherein:
the first module further includes a first control unit
configured to determine which switches within the first
inter-cell balance adjustment unit are to be switched to
passively reduce voltage variance among the first set of
battery cells based on the voltages detected by the first
battery monitoring unit while the battery cells are
charging; and
the second module further includes a second control
unit configured to determine which switches within the
second inter-cell balance adjustment unit are to be switched
to passively reduce voltage variance among the second set of
battery cells based on the voltages detected by the second
battery monitoring unit while the battery cells are charging.
(30)
The electric vehicle according to any one of (24) , (25) ,
(26) , (27) , (28) , and (29) , further comprising a battery
controller configured to:
receive a first cumulative voltage of the first set of
battery cells within the first module from the first control
unit;
receive a second cumulative voltage of the second set
of battery cells within the second module from the second
control unit; and
transmit control information to the first and second
modules indicating which switches of the inter-module
balance adjustment unit are to be switched to actively
reduce voltage variance among the first and second modules.
(31)
The electric vehicle according to any one of (24) , (25) ,
(26) , (27) , (28) , (29) , and (30) , wherein the battery
controller is configured to communicate a voltage of the
power reserve apparatus with the vehicle control electronics.
(32)
A power reserve apparatus comprising:
a plurality of battery cells;
modules, each including the plurality of battery cells;
a voltage detection unit that detects at least one cell
voltage of the plurality of battery cells;
a cell equalization unit that equalizes cell voltages;
and
a module equalization unit that equalizes voltages of
the modules between the modules,
wherein control performed by the cell equalization unit
is passive balance control, and
wherein control performed by the module equalization
unit is active balance control.
(33)
The power reserve apparatus according to (32) , further
comprising :
a control unit that generates control signals for
controlling the cell equalization unit and the module
equalization unit on the basis of the cell voltages.
(34)
The power reserve apparatus according to (32) or (33),
wherein the control unit is configured by a first
control unit provided for each of the plurality of modules
and a second control unit provided for the plurality of
modules in common,
wherein the cell voltage detected by the voltage
detection unit is transmitted from the first control unit to
the second control unit, and
wherein the second control unit generates a first
control signal for controlling the cell equalization unit
and a second control signal for controlling the module
equalization unit.
(35)
The power reserve apparatus according to (32) or (33) ,
wherein the control unit is configured by a first
control unit provided for each of the plurality of modules
and a second control unit provided for the plurality of
modules in common,
wherein the cell voltage detected by the voltage
detection unit is transmitted from the first control unit to
the second control unit,
wherein the first control unit generates a first
control signal for controlling the cell equalization unit,
and
wherein the second control unit generates a second
control signal for controlling the module equalization unit.
(36)
The power reserve apparatus according to any of (32) ,
(33) , (34) , and (35) ,
wherein the control unit performs the control performed
by the cell equalization unit and the module equalization
unit during charging.
(37)
The power reserve apparatus according to any of (32) ,
(33) , (34) , (35) , and (36) ,
wherein a first threshold value VI, a second threshold
value V2 smaller than the first threshold value VI, and a
third threshold value V 3 smaller than the second threshold
value V2 are set, and
wherein the control performed by the cell equalization
unit and the module equalization unit is repeated until the
cell voltages fall between the second threshold value V2 and
the third threshold value V3 .
(38)
The power reserve apparatus according to any of (32) ,
(33) , (34) , (35) , (36) , and (37) ,
wherein a first threshold value VI, a second threshold
value V2 smaller than the first threshold value VI, and a
third threshold value V3 smaller than the second threshold
value V2 are set, and
wherein the control performed by the module
equalization unit begins when a maximum cell voltage among
the cell voltages of the plurality of battery cells has
reached the first threshold value VI.
(39)
The power reserve apparatus according to any of (32) ,
(33), (34), (35), (36), (37), and (38),
wherein a first threshold value VI, a second threshold
value V2 smaller than the first threshold value VI, and a
third threshold value V3 smaller than the second threshold
value V2 are set, and
wherein the control performed by the cell equalization
unit begins when the cell voltages have reached the third
threshold value V3 .
(40)
The power reserve apparatus according to any of (32),
(33), (34), (35), (36), (37), (38), and (39),
wherein the control performed by the cell equalization
unit begins when the cell voltages have reached the third
threshold value V3 .
(41)
The power reserve apparatus according to any of (32) ,
(33), (34), (35), (36), (37), (38), (39), and (40),
wherein, after the control performed by the module
equalization unit begins, when at least one cell voltage has
reached a fourth threshold value V4 smaller than the first
threshold value VI, the at least one cell voltage is kept
constant .
(42)
The power reserve apparatus according to any of (32) ,
(33), (34), (35), (36), (37), (38), (39), (40), and (41),
wherein the fourth threshold value V4 is equal to the
second threshold value V2 .
(43)
The power reserve apparatus according to any of (32),
(33), (34), (35), (36), (37), (38), (39), (40), (41), and
(42),
wherein the control performed by the module
equalization unit begins, and
wherein, when the maximum cell voltage has reached the
second threshold value V2 after the first threshold value V I
is reached, the control performed by the module equalization
unit ends .
(44)
The power reserve apparatus according to any of (32) ,
(33), (34), (35), (36), (37), (38), (39), (40), (41), (42),
and (43) ,
wherein the module equalization unit includes
a series circuit configured by a first coil and a first
switching element connected parallel to a series connection
of the plurality of modules,
a second coil electromagnetically coupled with the
first coil, and
a second switching element connected in series with the
second coil, and
wherein the control unit individually controls the
first and second switching elements.
(45)
The power reserve apparatus according to any of (32) ,
(33), (34), (35), (36), (37), (38), (39), (40), (41), (42),
(43) , and (44) ,
wherein power is obtained from at least one first
module among the plurality of modules whose maximum cell
voltage among the plurality of battery cells is higher than
a maximum cell voltage among the plurality of battery cells
in another module by first and second switching elements
connected to the at least first module, and
wherein the obtained power is supplied to at least one
second module among the plurality of modules whose maximum
cell voltage among the plurality of battery cells is lower
than a maximum cell voltage among the plurality of battery
cells in another module from first and second switching
elements connected to the at least one second module.
(15)
The power reserve apparatus according to any of (32) ,
(33), (34), (35), (36), (37), (38), (39), (40), (41), (42),
(43) , (44) , and (45) ,
wherein power is obtained from at least one first
module among the plurality of modules whose maximum cell
voltage among the plurality of battery cells is higher than
the second threshold value V2 by first and second switching
elements connected to the at least one first module, and
wherein the obtained power is supplied to at least one
second module among the plurality of modules whose maximum
cell voltage among the plurality of battery cells is lower
than the second threshold value V2 from first and second
switching elements connected to the at least one second
module .
(47)
A power system comprising:
a power information transmission/reception unit that
transmits a signal to or receives a signal from another
device through a network,
wherein the transmission/reception unit causes the
power reserve apparatus according to (32) to charge or
discharge on the basis of received information.
(48)
An electric vehicle comprising:
a conversion apparatus that converts power supplied
from the power reserve apparatus according to (32) into
driving force of the vehicle and a control apparatus that
processes information relating to vehicle control on the
basis of information relating to the power reserve apparatus.
"Power Reserve Apparatus in House as Application Example"
An example in which the present disclosure is applied
to a power reserve apparatus used in a house will be
described with reference to Fig. 20. For example, in a
power reserve apparatus 100 used in a house 101, a
centralized power system 102 such as thermal power
generation 102a, nuclear power generation 102b, or hydraulic
power generation 102c supplies power to a power storage
apparatus 103 through a power network 109 , an information
network 112, a smart meter 107, a power hub 108, and the
like. At the same time, an independent power supply such as
a domestic generation apparatus 104 supplies power to the
power storage apparatus 103 . The power supplied to the
power storage apparatus 103 is stored. Power used in the
house 101 is provided using the power storage apparatus 103.
The same power reserve apparatus may be used not only in the
house 101 but also in a building.
In the house 101, the generation apparatus 104, power
consumption apparatuses 105, the power storage apparatus 103,
a control apparatus 110 that controls various apparatuses,
the smart meter 107, and sensors 111 that obtain various
pieces of information are provided. These apparatuses are
connected to one another by the power network 109 and the
information network 112. A s the generation apparatus 104,
solar cells, fuel cells, or the like are utilized, and
generated power is supplied to the power consumption
apparatuses 105 and/or the power storage apparatus 103. The
power consumption apparatuses 105 are a refrigerator 105a,
an air conditioning apparatus 105b, a television receiver
105c, a bath 105d, and the like. Furthermore, the power
consumption apparatuses 105 include electric vehicles 106.
The electric vehicles 106 are an electric car 106a, a hybrid
car 106b, and an electric motorcycle 106c.
The above-described battery unit in the present
disclosure is applied to the power storage apparatus 103.
The power storage apparatus 103 is configured by a secondary
battery or a capacitor. For example, the power storage
apparatus 103 is configured by a lithium-ion battery. The
lithium- ion battery may be of a fixed type or may be one
that is used in the electric vehicles 106. The smart meter
107 has functions of measuring the amount of commercial
power used and transmitting the measured amount to a power
company. The power network 109 may be any of, or a
combination between, direct-current power feed, alternatingcurrent
power feed, and non- contact power feed.
The various sensors 111 are, for example, a human
detection sensor, an illuminance sensor, an object detection
sensor, a power consumption sensor, a vibration sensor, a
contact sensor, a temperature sensor, an infrared sensor,
and the like. Information obtained by the various sensors
111 is transmitted to the control apparatus 110. Energy
consumption can be kept at minimum by automatically
controlling the power consumption apparatuses 105 while
detecting meteorological conditions, the states of persons,
and the like using the information from the sensors 111.
Furthermore, the control apparatus 110 can transmit
information relating to the house 101 to an external power
company or the like through the Internet.
The power hub 108 performs processes such as division
of a power line and direct-current/alternating-current
conversion. As communication methods used by the
information network 112 connected to the control apparatus
110, a method in which a communication interface such as a
UART (Universal Asynchronous Receiver-Transceiver) is used
and a method in which a sensor network according to a
wireless communication standard such as Bluetooth, ZigBee,
or Wi-Fi is utilized are available. The Bluetooth method is
applied to multimedia communication, and communication of
one-to-many connections is possible. In ZigBee, the
physical layer according to IEEE (Institute of Electrical
and Electronics Engineers) 802.15.4 is used. IEEE 802.15.4
is the name of a short-range wireless network standard
called PAN (Personal Area Network) or W (Wireless) PAN.
The control apparatus 110 is connected to an external
server 113 . The server 113 may be managed by any of the
house 101, the power company, and a service provider.
Information transmitted or received by the server 113 is,
for example, power consumption information, life pattern
information, the power rate, whether information, natural
disaster information, or information relating to a power
transaction. These pieces of information may be transmitted
from, or received by, a domestic power consumption apparatus
(for example, the television receiver) , or may be
transmitted from, or received by, an apparatus (for example,
a mobile telephone or the like) outside the house. These
pieces of information may be displayed on a device having a
display function, such as, for example, the television
receiver, the mobile telephone, or a PDA (Personal Digital
Assistant) .
The control apparatus 110 that controls various
components is configured by a CPU (Central Processing Unit) ,
a RAM (Random Access Memory) , a ROM (Read Only Memory) , and
the like, and stored in the power storage apparatus 103 in
this example. The control apparatus 110 is connected to the
power storage apparatus 103, the domestic generation
apparatus 104, the power consumption apparatuses 105, the
various sensors 111, and the server 113 by the information
network 112, and, for example, has a function of adjusting
the amount of commercial power to be used and the amount of
power to be generated. It is to be noted that a function of
making a power transaction in a power market or the like may
also be included.
As described above, power can be stored not only in the
centralized power system 102 such as the thermal power
generation 102a, the nuclear power generation 102b, or the
hydraulic power generation 102c, but also in the power
storage apparatus 103 in the form of power generated by the
domestic power generation apparatus 104 (solar photovoltaic
power generation or wind power generation) . Therefore, even
if the power generated by the domestic power generation
apparatus 104 varies, the amount of power to be transmitted
to the outside can be kept constant, only necessary power
can be discharged, or other types of control can be
performed. For example, the following usage is possible:
power obtained by the solar photovoltaic power generation is
stored in the power storage apparatus 103 and midnight power,
whose cost is low, is stored in the power storage apparatus
103 at night, while the power stored in the power storage
apparatus 103 is discharged during the day, when cost is
high.
It is to be noted that although an example in which the
control apparatus 110 is stored in the power storage
apparatus 103 has been described, the control apparatus 110
may be stored in the smart meter 107 or may be configured
independently. Furthermore, the power reverse apparatus 100
may be used for a plurality of houses in an apartment area,
or may be used for a plurality of detached houses.
"Power Reserve Apparatus in Vehicle as Application Example"
An example in which the present disclosure is applied
to a power reserve apparatus used in a vehicle will be
described with reference to Fig. 21. Fig. 21 schematically
illustrates an example of the configuration of a hybrid car
adopting a series hybrid system to which the present
disclosure is applied. The series hybrid system is a car
that runs with a power driving force transducing apparatus
using power generated by a generator driven by an engine or
the same power that has been stored in a battery.
In this hybrid car 200, an engine 201, a generator 202,
a power driving force transducing apparatus 203, a driving
wheel 204a, a driving wheel 204b, a wheel 205a, a wheel 205b,
a battery 208, a vehicle control apparatus 209, various
sensors 210, and a charging port 211 are mounted. The
above-described battery unit in the present disclosure is
applied to the battery 208.
The hybrid car 200 runs using the power driving force
transducing apparatus 203 as the power source. An example
of the power driving force transducing apparatus 203 is a
motor. The power driving force transducing apparatus 203
operates using power stored in the battery 208, and the
rotational force of the power driving force transducing
apparatus 203 is transmitted to the driving wheels 204a and
204b. It is to be noted that, by adopting direct current -
alternating current (DC-AC) conversion or reverse conversion
(AC-DC conversion) at a necessary point, the power driving
force transducing apparatus 203 may be adopted regardless of
the power driving force transducing apparatus 203 being an
alternating-current motor or a direct-current motor. The
various sensors 210 control the engine speed through the
vehicle control apparatus 209 and controls the opening of a
throttle valve (throttle opening) , which is not illustrated.
The various sensors 210 include a speed sensor, an
acceleration sensor, and an engine speed sensor.
The rotational force of the engine 201 is transmitted
to the generator 202, and the power generated by the
generator 202 using the rotational force can be stored in
the battery 208 .
When the speed of the hybrid car is decreased by a
braking mechanism, which is not illustrated, the resisting
force at the time of the decrease in speed is added to the
power driving force transducing apparatus 203 as rotational
force, and regenerative power generated by the power driving
force transducing apparatus 203 using the rotational force
is stored in the battery 208.
When connected to a power supply outside the hybrid car,
the battery 208 can receive supply of power from the
external power supply using the charging port 211 as an
input port and store the received power. Although not
illustrated, an information processing apparatus that
processes information relating to vehicle control on the
basis of information relating to the secondary battery may
be included. Such an information processing apparatus may
be, for example, an information processing apparatus that
displays the remaining amount of power in the battery on the
basis of information relating to the remaining amount of
power in the battery.
It is to be noted that, in the above description, a
series hybrid car that runs with a motor using power
generated by a generator driven by an engine or the same
power that has been stored in a battery has been described
as an example. However, the present disclosure can be
effectively applied to a parallel hybrid car that uses three
methods, that is, a run using only the engine, a run using
only the motor, and a run using both the engine and the
motor, while switching the method as necessary. Furthermore,
the present disclosure can be effectively applied to a socalled
electric vehicle that runs using only a driving motor
without using an engine.
"Modifications"
Although the embodiments of the present disclosure have
been specifically described, the present disclosure is not
limited to the above -described embodiments, and various
modifications based on the technical idea of the present
disclosure are possible. For example, the configurations,
the methods, the processes, the shapes, the materials, and
the values described in the above embodiments are merely
examples, and configurations, methods, processes, shapes,
materials, and values different from these can be used as
necessary .
In addition, the configurations, the methods, the
processes, the shapes, the materials, and the values
described in the above embodiments may be combined with one
another insofar as the scope of the present disclosure is
not deviated from.
Reference Signs List
MOD, MODI to MODN power storage module
ICNT control box
CNT controller of each power storage module
ICNT control box
Bl to Bn battery block
BB1 to BBn battery unit
ISC1 to ISCn insulation unit
COM1 to COMn communication unit
21 multilayer wiring board
23, 24 printed board antenna
LY1 to LY4 wiring layer
l to 14 primary-side coil
SI to S14 primary-side switch
W01 to W014 secondary- side coil
SOI to S014 secondary- side switch
Tl to T14 flyback transformer
C1+, Cl- common power supply line
CV common power supply voltage
51 power storage element

CLAIMS
[Claim 1 ]
A power reserve apparatus comprising:
a first module including:
a first set of battery cells; and
a first inter-cell balance adjustment unit
configured to use passive balancing to reduce voltage
variance among the first set of battery cells;
a second module including:
a second set of battery cells; and
a second inter-cell balance adjustment unit
configured to use passive balancing to reduce voltage
variance among the second set of battery cells; and
an inter-module balance adjustment unit configured to
use active balancing to reduce voltage variance among the
first and second modules.
[Claim 2 ]
The power reserve apparatus of Claim 1 , wherein:
the first module further includes a first battery
monitoring unit configured to detect voltages of each of the
battery cells within the first set; and
the second module further includes a second battery
monitoring unit configured to detect voltages of each of the
battery cells within the second set.
[Claim 3 ]
The power reserve apparatus of Claim 2 , wherein:
the first module further includes a first control unit
configured to determine which switches within the first
inter-cell balance adjustment unit are to be switched to
passively reduce voltage variance among the first set of
battery cells based on the voltages detected by the first
battery monitoring unit; and
the second module further includes a second control
unit configured to determine which switches within the
second inter-cell balance adjustment unit are to be switched
to passively reduce voltage variance among the second set of
battery cells based on the voltages detected by the second
battery monitoring unit.
[Claim 4 ]
The power reserve apparatus of Claim 3 , further
comprising a battery controller configured to:
receive a first cumulative voltage of the first set of
battery cells within the first module from the first control
unit ;
receive a second cumulative voltage of the second set
of battery cells within the second module from the second
control unit; and
transmit control information to the first and second
modules indicating which switches of the inter-module
balance adjustment unit are to be switched to actively
reduce voltage variance among the first and second modules .
[Claim 5 ]
The power reserve apparatus of Claim 4 , wherein the
battery controller and the first and second modules are
configured for each of the battery cells, to stop charging a
battery cell when the battery cell reaches a first voltage
threshold.
[Claim 6 ]
The power reserve apparatus of Claim 4 , wherein the
battery controller and the first and second modules are
configured to reduce variance among the battery cells until
each of the voltages of each of the battery cells are
between a second voltage threshold and a third voltage
threshold.
[Claim 7 ]
The power reserve apparatus of Claim 6 , wherein a
difference between the second voltage threshold and the
third voltage threshold is approximately 30 millivolts.
[Claim 8 ]
The power reserve apparatus of Claim 4 , wherein the
battery controller and the first and second modules are
configured to perform preliminarily charging on any of the
battery cells that fall below a fourth voltage threshold.
[Claim 9 ]
The power reserve apparatus of Claim 4 , wherein:
the first and second modules are configured to
passively reduce voltage variance using the respective first
and second inter-cell balance adjustment units during a
first time period, and
the battery controller is configured to actively reduce
voltage variance using the inter-module balance adjustment
unit during a second time period after the first time period.
[Claim 10]
The power reserve apparatus of Claim 4 , further
comprising a power storage element configured to store a
common power supply voltage that is substantially equal to a
voltage of the modules when fully charged.
[Claim 11]
The power reserve apparatus of Claim 10, wherein:
the first module includes:
a first primary-side coil electrically connected to
the power storage element and a first switch,
a first secondary-side coil electrically connected
to the first set of battery cells and a second switch, and
a first magnetic core inductively coupled to the
first primary-side coil and the first secondary- side coil;
and
the second module includes:
a second primary- side coil electrically connected
to the power storage element and a third switch,
a second secondary- side coil electrically connected to
the second set of battery cells and a fourth switch, and
a second magnetic core inductively coupled to the
second primary-side coil and the second secondary- side coil.
[Claim 12]
The power reserve apparatus of Claim 11, wherein the
battery controller is configured to indicate a sequence in
which the first, second, third, and fourth switches are to
be switched to actively reduce voltage variance among the
first and second modules.
[Claim 13]
The power reserve apparatus of Claim 11, wherein the
battery controller is configured to activate the first
switch for a time period then activate the second switch for
a second time period to charge the power storage element to
reduce a voltage of the first set of battery cells when the
first set of battery cells has a higher voltage than the
second set of battery cells.
[Claim 14]
The power reserve apparatus of Claim 13, wherein the
battery controller is configured to activate the fourth
switch for a third time period then activate the third
switch for a fourth time period to increase the voltage of
the second set of battery cells.
[Claim 15]
A power reserve method comprising:
detecting voltages of a first set of battery cells in a
first module;
detecting voltages of a second set of battery cells in
a second module;
determining a first cumulative voltage of the first
module based on the voltages of the first set of battery
cells ;
determining a second cumulative voltage of the second
module based on the voltages of the second set of battery
cells ;
controlling a first group of switches to actively
balance the cumulative voltages among the first and second
modules; and
controlling a second group of switches to passively
balance voltages among the battery cells within the first
module and voltages among battery cells within the second
module .
[Claim 16]
The power reserve method of Claim 15, wherein actively
balancing of the cumulative voltages of the first and second
set of modules occurs sequentially with passively balancing
the voltages among the battery cells within the first module
and the voltages among battery cells within the second
module.
[Claim 17]
The power reserve method of Claim 15, further
comprising charging the first and second sets of batterycells
.
[Claim 18]
The power reserve method of Claim 17, wherein the first
and second modules are actively balanced after at least the
voltage of one of the battery cells within the first and
second sets exceeds a first voltage threshold.
[Claim 19]
The power reserve method of Claim 18, wherein active
balancing includes:
determining a first maximum voltage of the battery
cells within the first set;
determining a second maximum voltage of the battery
cells within the first set;
transferring power from the first module to the second
module if the second maximum voltage is greater than a
second voltage threshold and the first maximum voltage is
less than the second voltage threshold; and
transferring power from the second module to the first
module if the first maximum voltage is greater than the
second voltage threshold and the second maximum voltage is
less than the second voltage threshold.
[Claim 20]
The power reserve method of Claim 19, wherein active
balancing of the first and second sets of battery cells ends
after the voltages of all of the battery cells are less than
the second voltage threshold.
[Claim 21]
The power reserve method of Claim 17, wherein passive
balancing is applied to each battery cell that exceeds the
third threshold during changing.
[Claim 22]
The power reserve method of Claim 17, wherein the first
and second sets of battery cells are charged until the
voltages of first and second sets of battery cells are less
than the second threshold voltage, greater than a third
threshold voltage, and a variance between each of the
voltages of the battery cells is less than a fourth voltage
threshold .
[Claim 23]
The power reserve method of Claim 17, wherein the
fourth voltage threshold is approximately 30 millivolts.