Description
Title of Invention
POWER STORAGE DEVICE, POWER STORAGE CONI'ROL DEVICE, AND
5 POWER STORAGE CONTROL METI-IOD
Teclinical Field
[OOOl]
Tlie present disclosure relates to a power storage device, a power storage
10 control device, and a power storage control method. More specifically, the present
disclosure relates to a power storage device, a power storage control device, and a
power storage control method for storing electricity in a cell.
Background Art
15 [0002]
Techlologies of equalizing voltages of a plurality of cells which are
connected in series have been proposed in the related art. Patent Literature 1, for
example, proposes an inter-battery voltage equalization circuit in which a terminal
voltage of a capacitor is boosted by a voltage of a boosting element in which electric
20 charges have accumulated and then the electric charges are transfetred to a secondary
battery.
Citation List
Patent Literature
25 [0003]
Patent Literature: JP 2013-13291A
Summary of Invention
Technical Problem
30 [0004]
When a potential difference between a plurality of serially connected cells is
high in a case in which voltages of the cells arc to be eq~~alizcadn, excessive current
nlay flow to a cell that will receive energy and thus a burden is imposed thereon.
[0005]
The present disclosurc provides a powcr storage device, a powcr storage
5 control dcvice, and a power storagc control method for suppressing a burden
inlposed on a cell \vhen voltages of cells are equalized.
Solution to Problem
[0006]
10 According to the present disclosure, a power storage device includes: a
plurality of cells which arc connccted in scries; a series resonance circuit configured
to include a reactor and a capacitor; and a power storage control devicc configured to
control a connection state of the cells and the scrics resotlarxcc circuit. The power
storage control devicc causes energy to be transferred between equal numbers of
15 cells via the series resonance circuit.
After the powcr storagc control device connects first cells including at least
one cell to the series resonance circuit, the power storagc control devicc may comiect
second cclls which include cells equal in number to the first cclls and have a lower
total voltage than the first cclls to the scries resonance circuit.
20 In this case, the power storage control device may select a plurality of
consecutive cells as the first cells, and select consecutive cclls equal in number to the
first cells as the second cells.
On the other hand, when the first cells are connected to the series resonance
circuit and then the direction of a current flowing in the scries resonancc circuit
25 changes, the power storage control device may discolu~cct the first cells from the
series resonance circuit. In this case, when the second cells are connccted to the
series resonance circuit and then the direction of a currcnt flowing in the scries
resonance circuit changes, the power storage control dcvice may disconnect the
second cells fio111 the series resonance circuit. In this case, the power storagc
30 control dcvice may maintain a state in which all the cells are disconnected fiom the
series resonance circuit during a set period after the first and/or second cells are
disconnected fronl the series resonance circuit, and determine whether or not transfer
of energy is to be finished based on a voltage of the cells during the set period.
The series resonance circuit may include a resistance, and the power storage
coritrol device may detect the direction of a current flowing in the series resonance
5 circuit based on a potential difference of both ends of the resistance.
The power storage control device may switch connection of tlie series
resonance circuit and the cells using a resonance frequency of tlie series resonance
circuit.
A resonance frequency of the series resonance circuit may be a frequency
10 when an imaginary component in a Cole-Cole plot of internal impedances of the cells
measured using an AC impedance method becomes 0.
The power storage control device may cause a cell having a maximum
voltage to be included in the first cells. In this case, the power storage control
device may cause a cell having a minimum voltage to be included in the secolld cells.
15 The power storage device may further include: a switch configured to
connect or disconnect the cells and the series resonance circuit. The power storage
cot~trold evice may control a connection state of the cells and the series resonance
circuit by controlling an operation of the switch.
Tlie cells may have a discharge characteristic that a change of a voltage is
20 0.25 V or lower in a series of sections spanning 50% or more of a section of a charge
ratio of 0% to 100%.
According to the present disclosure, a power storage control device is
configured to control a connection state of a plurality of cells which are connected in
series and a series resonance circuit which includes a reactor and a capacitor, and to
25 cause energy to be transferred between equal numbers of cells via the series
resonatlce circuit.
According to the present disclosure, a power storage control method is
carried out by a control device which col~trols a connection state of a plurality of
cells \ifl~ichar e connected in series and a series resonance circuit wliich includes a
30 reactor and a capacitor to cause energy to be transfc~~ebdet ween equal numbers of
cells via the series resonance circuit.
Advantageous Effects of Invention
[0007]
According to the prese~lt disclosure, a burden imposed on a cell wvl~etl
5 voltages of cells are equalized can be suppressed.
Brief Description of Drawings
[OOOS]
[FIG. 11 FIG. 1 is a diagam schen~atically showing a configuration example of a
10 power storage device of a first ernhodimel~t of the present disclosure, in which A
shows a co~lnection state of one cell and a series resonance circuit, and B shows a
connectiot~s tate of another cell and the series resollance circuit.
[FIG. 21 FIG. 2 is a diagram scl~ematically showing a configuration of a power
storage device of a first modified example of the first enlbodiment of the present
15 disclosure, in which A shows a con~~ectiostna te of two cells and a series resonance
circuit, and B shows a connection state of two other cells and the series resonance
circuit.
[FIG. 31 FIG. 3 is a diagram schematically showing a configuration of a power
storage device of a second modified example of the first embodiment of the present
20 disclosure, in which A shows a connection state of two cells and a series resonance
circuit and B shows a state in which one of the two cells and another cell are
connected to the series resonance circuit.
[FIG 41 FIG. 4 is a diagram sche~natically showing a co~lfiguration example of a
power storage device of a second embodiment of the present disclosure.
25 [FIG. 51 FIG. 5 is a diagram schen~atically showing a configuration example of a
power storage control device of the power storage device of the second embodiment
of the present disclosure.
[FIG. 61 FIG. 6 is a flowcha~t showing an operation example of the power storage
device ofthe second embodiment of the present disclosure.
30 [FIG. 71 FIG. 7 is a diagram sche~natically showing a configuration of a power
storage device of a first modified example of the second embodiment of the presetlt
disclosure.
[FIG. 81 FIG. 8 is a diagram scl~eematically showing a configuration example of a
power storage device of a third eelllbodi~nenot f the present disclosure.
[FIG 91 FIG. 9 is a diagram schematically showing a ~ o ~ g u r a t i oexna mple of a
5 power storage control device of the power storage device of the third etnbodiment of
the present disclosure.
[FIG. 101 FIG. 10 is a diagram showing the power storage device of tile third
embodiment of the present disclosure as an equivalent circuit.
[FIG. 111 FIG. 11 includes time charts showing an operation example of the power
10 storage device of the third embodiment of the present disclosore, among which A is a
time chart showing a current flowing in a series resonance circuit, B is a time chart
showing a voltage of a cell, C is a time chart showing open and closed states of a first
switch, and D is a time chart showing open and closed states of a second switch.
[FIG. 121 FIG. 12 is a diagram showing a configuration example of a resonance
15 current direction detection unit of a power storage device of a first modified example
of the third embodiment of the present disclosure.
[FIG. 131 FIG. 13 includes time charts showing an operation example of the
resonance cuuent direction detection unit of the power storage device of the first
modified example of the third embodiment of the present disclosure. Specifically,
20 A thereof shows a resonance current flowing in a series resonance circuit, B shows
an output of a first comparatol; C shows an output of a second conlparator, D shows
an output of a first D-type flip-flop, E shows an output of a second D-type flip-flop,
F shows an output of a first AND circuit, and G shows an output of a second AND
circuit.
25 [FIG. 141 FIG. 14 is a flowchart showing an operation example of the power storage
device of the first modified example of the third embodiment of the present
disclosure.
[FIG. 151 FIG. 15 includes time charts showing an operation example of a power
storage device of a fourth embodiment of the present disclosure, anlong which A is a
30 time chart showing a resonance current flowing in a series resonance circuit, B is a
time chart showing open and closed states of a first switch, and C is a time chart
sliowing open and closed states of a second switch.
[FIG. 161 FIG. 16 is a flowchart showing the operation example of the power storage
device of the fourth embodiment of the present disclosure.
[FIG. 171 FIG. 17 includes time charts showing an operation example of a power
6 storage device of a first nlodified example of the fourth enlbodinlent of the present
disclosure, in which A is a time chart showing a resonance c~ti~efnlotw ing in a series
resonance circuit, B is a time chart showing open and closed states of a first switch,
and C is a time chart showing open and closed states of a second switch.
[FIG. 181 FIG. 18 is a flowvcliart showing the operation example of the power storage
10 device of the fisst modified example of the fourth embodiment of the present
disclosure.
[FIG. 191 FIG. 19 is a diagram schenlatically showing a configuration example of a
part of a power storage device of a fifth ernbodiment of the present disclosure.
[FIG. 201 FIG. 20 is a diagram sliowing the power storage device of the fifth
15 embodiment of the present disclosure as an equivalent circuit.
[FIG. 211 FIG. 21 is a diagram sche~naticallys howing a configuration example of a
part of a power storage device of a first modified example of the fifth embodiment of
the present disclosure.
[FIG. 221 FIG. 22 is a diagram sche~naticallys howing a configuration example of a
20 part of a power storage device of a second modified example of the fifth embodiment
of the present disclosure.
[FIG. 231 FIG. 23 is a flowchart sliowing an operation example of a power storage
device of a sixth embodiment of the present disclosure.
[FIG. 241 FIG. 24 is a Cole-Cole plot diagram for describing a configuration exa~ilple
25 of a power storage device of a seventh embodiment of the present disclosure.
[FIG. 251 FIG. 25 is a Cole-Cole plot diagram for describing a configuration example
of a power storage device of a first modified example of the seventh embodiment of
the present disclosure.
[FIG. 261 FIG. 26 is a discharge curve diagram of a cell for describing a configuratio~~
30 example of a power storage device of an eighth embodiment of the present disclosure.
Description of E~i~boditne~~ts
[OOOS]
Hereinafter, exemplary embodiments for inlplenletlting the present
disclosure xvill be described with reference to the drawings. The plurality of
5 et~lbodiments described below are for showing representative examples of the
embodiments of tlie present disclosure, and the scope of tlie present disclosure should
not be narrowly interpreted according to tlie~ll. In addition, in each of the
embodiments, the same reference numerals are given to constituent elements
corresponditlg to each other to omit overlapping descriptioti. Description will be
10 provided in the following order.
1. First embodiment
(Example of a power storage device in which energy is transferred between equal
numbers of cells)
2. First modified example of the first embodiment
15 (Example of a power storage device in which energy is transferred between cell
groups having equal numbers of cells)
3. Second modified example of the fist embodiment
(Example of a power storage device in which energy is transferred between cell
groups having equal numbers of cells among which some of the cells overlap)
20 4. Second embodiment
(Example of a power storage device in which energy is transferred between a first
cell having a higher voltage and a second cell having a lower voltage)
5. First modified example of the second embodiment
(Example of a power storage device in which energy is transferred between first cells
25 including a plurality of cells and second cells including cells equal in number to the
first cells)
6. Third embodinlent
(Example of a power storage device which switches comlection between a cell and a
series resonance circuit according to a current OA)
30 7. First modified example of the third embodiment
(Example of a power storage device wliich switches co~u~ectiobnet ween a cell and a
series rcsonatlce circuit according to a change of a direction of a current)
8. Fourth embodiment
(Example of a power storage device which maintains a state in which all cells are
disconnected fro~n a series resonance circuit during a period set between
5 disconnection of a second cell fsom the series resonance circuit and next connection
of a first cell to the series resonance circuit)
9. First modified example of the fourth enlboditnent
(Example of a power storage device \vl~ich maintains a state in which all cells are
disconnected from a series resonance circuit during a period set between
10 disconnection of a first cell fiom the series resonance circuit and connection of a
second cell to the series resonance circuit)
10. Fifth embodiment
(Example of a power storage device in which a series resonance circuit has a
resistance)
15 11. First modified example of the fifth embodiment
(Example of a power storage device \vhicl~ detects a direction of a resonance curret~t
using a resistance)
12. Second modified example of the fifth embodiment
(Example of a power storage device in urllich a resistance of a series resonance
20 circuit is a parasitic resistance)
13. Sixth embodiment
(Example of a power storage device which switches connection between a cell and a
series resonance circuit using a resonance frequency of the series resonance circuit)
14. Seventh embodiment
25 (Example of a power storage device in which a series resonance circuit has a
resonance frequency adaptive to a Cole-Cole plot)
15. First modified example of the seventh embodiment
(Example of a power storage device in which a resonance frequency of a series
resonance circuit is set it1 consideration of a Cole-Cole plot of each charge ratio)
30 16. Eighth embodiment
(Example of a power storage device to which a cell having a substantially flat
discharge characteristic is applied)
[OOIO]

[Device cotifiguration example]
5 FIG. 1 is an overall diagram sche~naticallys howing a configuration example
of a power storage device 100 of the present embodiment. The power storage
device 100 includes a plurality of cells 110a and 1 lob, a series resonance circuit 120,
and a power storage control device 130 as shown in FIG. 1.
[OOll]
10 [Cells 11 Oa and 1 lob]
The cells llOa and llOb are connected in series as showti in FIG. 1. All
the cells 110a and llOb can be charged and discharged. In other words, each of the
cells 1 lOa and 1 lob can accutnulate a charge current supplied fiotn a charge device
which is not illustrated as electric charge during charge, and can supply accumulated
15 electric charge to a load which is not illustrated as a discharge current during
discharge.
[0012]
The number of cells 110a and 110b is not limited to two as shown in FIG 1
as long as they are plural. The cells llOa and llOb may be configured according to
20 the same standard or different standards. The cells llOa and llOb may each be
single cells or battery packs. When the cells llOa and llOb are battery packs,
connection inside the battery packs may be made in series, in parallel, or both. A
more preferable fort11 of the cells llOa and llOb will be described in 4 6 . Eighth
embodinlent> below.
25 [0013]
[Series resonance circuit 1201
As shown in FIG. I, the series resonance circuit 120 has a reactor 121 and a
capacitor 122. The reactor 121 and the capacitor 122 are connected in series.
[0014]
30 A current flotvs in the series resonance circuit 120 according to inductive
reactance of the reactor 121 and capacitive reactance of the capacitor 122. Selfinductance
[HI of the reactor 121 and electrostatic capacitance [F] of the capacitor
122 are not limited. A nlore preferable mode of the series resonance circuit 120
will be described in 114. Seventh embodiment> belo\v.
[OOI 51
5 [Power storage control device 1301
The power storage control device 130 controls electrical connection states
of the cells l l Oa and llOb and the series resonance circuit 120. Here, in FIG. I, a
co~u~ectiosnta te of the cells llOa and llOb and the series resonance circuit 120
foniled according to control of the power storage control device 130 is schematically
10 indicated by bidirectional arrows A. In addition, in FIG. 1, the power storage
control device 130 is configured to cotitrol the connection state, which is
scliematically shown by dotted lines in the drawing. Further, FIG. 1A shows a state
in which the one cell llOa is connected to the series resonance circuit 120 and tlie
other cell llOb is disconnected from tlie series resonance circuit 120. On the other
15 hand, FIG. IB shows a state in which the one cell llOa is disconnected from tlie
series resonance circuit 120 and the other cell llOb is connected to the series
resonance circuit 120.
[OOI 61
M~ena p otential difference between a cell on a power supply side that gives
20 energy and a cell on a power reception side that receives the energy is significant
during a voltage equalizing process, there is concern of an excessive current flowing
to the cell on the power reception side which may damage the cell on the power
reception side. In the present disclosure, for one purpose of suppressing a burden
imposed on the cell on the power reception side caused by a potential difference
25 between the cell on a power supply side and the cell on the power reception side, the
power storage control device 130 is configured to cause energy to be transferred
between equal numbers of cells. Specificallj: the power storage control device 130
causes energy to be transferred between the equal nunlbers of cells via the series
resonance circuit 120 by, for example, selectively forming the connection states
30 shown in FIGS. 1A and 1B.
[0017]
Here, transfer of energy between the equal numbers of cells in the preseut
disclosure is perfomled by ~novinge nergy from n (11 is an arbitrary natural nunlber)
cells 011 a power supply side to a series resonance circuit and moving the energy from
the series resonance circuit to n cells on a power reception side. In other words,
5 transfer of energy between the equal nunlbers of cells in the present disclosure is
performed by selectively connecting n cells on the power supply side and 11 cells 011
the power reception side to a series resonance circuit. In addition, transfer of
energy between the equal numbers of cells in the present disclosure does not entail
transfer of energy between a power storage element that is included in neither the
10 equal numbers of cells nor the series resonance circuit, such as a cell other than the
equal numbers of cells, a capacitor other than the capacitor of the series resonance
circuit, or the like.
[OOI 81
The power storage control device 130 may control a connection state of the
15 cells IlOa and 1 lob and the series resonance circuit 120 by electrically controlling an
electronic device which connects or disconnects the cells llOa and llOb and the
series resonance circuit 120. In this case, the electronic device may include a
switching device or the like.
[OOI 91
20 The power storage control device 130 may be configured with an electronic
device or the like. In this case, the electronic device may include an arithmetic
processing device such as a central processing unit (CPU) or a micro-processing unit
(MPU), a storage device such as a random access metnoly (RAM) or a read only
tnemoly (ROM). The ROM may store data and a program for realizing a fi~t~ction
25 of the power storage control device 130, i.e., a program for causing a computer to
function as the power storage control device 130. By executing the program stored
in the ROM, the arithmetic processing device may realize the function of the power
storage cotltrol device 130. The RAM may be used as a work area of the arithmetic
processing device or the like. The above constituent elements, howevel; are not
30 limited to the above configurations.
[0020]
[Device operation example]
An operation cxa~iiple of the power storage device 100 \vill be described
below. The operation exanlple below includes an embodiment of tlie power storage
cotltrol method according to tlie present disclosure. The power storage control
5 method according to the present disclosure, however, may be realized with a
configuration other than that of the power storage device 100.
[00211
hi the present embodiment, as the power storage control device 130 controls
comiection states of the cells llOa and llOb and the series resonance circuit 120 as
10 showvn in FIGS. IA and lB, tlie cells llOa and llOb are selectively co~lnectedto the
series resonance circuit 120. The cells llOa and llOb that are connected to the
series resonance circuit 120 transfer a current to move energy with the series
resonance circuit 120 interposed therebetween. Accordingly, transfer of energy is
performed between the cells llOa and llOb via the series resonance circuit 120.
15 For example, when energy retained by the one cell llOa is greater than energy
retained by the other cell IlOb, energy is supplied fiom the cell 110a to the cell 110b
via the series resonance circuit 120. After the supply of energy, unevemess in
energy between the cells 1lOa and 110b is decreased or resolved.
roo221
20 As described above, according to the power storage device 100 of the
present embodiment, under a condition that there is a small potential difference
between equal numbers of cells, is., between the one cell llOa and the other cell
110b, the power storage control device 130 can cause energy to be transferred
between the cells using a low current. If the series resonance circuit 120 is boosted
25 by a boosting element, it is difficult to transfer energy with a low current. In
addition, since energy can be transferred via the series resonance circuit 120, a speed
of a voltage equalizing process can be raised more than when only a capacitor is used,
and a capability of preventing a short circuit of cells is higher than when only a
reactor is used. In other words, according to the power storage device 100 of the
30 present embodiment, a burden imposed on the cells 110 is low and an efficient and
stable voltage equalizing process, i.e., an active cell balancing process, is possible.
[0023]
a. First modified example of the first embodiment>
FIG. 2 is an overall diagram schematically showing a configuration of a
power storage device 100 of a first modified example of tlie present embodiment.
5 The power storage device 100 of tlie present rilodified example has a different cell
disposition form and connection state of cells and a series resonance circuit 120
fo~nledb y a power storage control device 130 from the power storage device 100 of
FIG. 1. The difference will be described in detail below.
[0024]
10 As shown in FIG. 2, the power storage device 100 of the present lnodified
example includes four cells 1 lea, 1 lob, 110c, and 1 lOd that are connected in series.
[0025]
FIG. 2 schematically shows connection states of the cells 110a to 11 0d and
the series resonance circuit 120 formed by contsol of the power storage control
15 device 130. Specifically, FIG. 2A shows a state in which the two cells llOa and
llOb are connected to tlie series resonance circuit 120. In addition, FIG. 2A shows
a state in which the other two cells llOc and llOd are discorinected from the series
resonance circuit 120. On the other hand, FIG. 2B shows a state in which the two
cells 110a and 1 lob that are connected to the series resonance circuit 120 in FIG. 2A
20 are disconnected fsom the series resonance circuit 120. In addition, FIG. 2B shows
a state in which the two cells llOc and llOd that are disconnected fsom the series
resonance circuit 120 in FIG 2A are connected to the series resonance circuit 120.
[0026]
The power storage control device 130 selectively forms connection states
25 shown in FIG. 2A and 2B to cause energy to be transferred betureen cell groups
having the equal numbers of cells via the series resonance circuit 120. Other
configurations and operations are basically the sanle as those of the power storage
device 100 of FIG 1.
[0027]
30 According to the present tnodified exanlple, the same effect as the power
storage device 100 of FIG. 1 can be exhibited, and by causing energy to be
transferred between cell groups, a voltage equalizing process is possible with an even
lower current havi~lga niore reduced potential difference. Furthermore, a degree of
freedom in the mode of the voltage equaliziug process can be improved.
[0028]
5 13. Second modified example of tlie first embodiment>
FIG. 3 is an overall diagram scl~ematically showing a collfiguration of a
power storage device 100 of a second modified example of tlie present embodiment.
The power storage device 100 of the present modified example has a different cell
disposition form aud connection state of cells and a series resonance circuit 120
10 formed by a power storage control device 130 from the power storage devices 100 of
FIGS. 1 and 2. The difference will be described in detail below.
[0029]
As shown in FIG. 3, the power storage device 100 of the present modified
example includes three cells 11 Oa, 1 lob, and 11 0c that are connected in series.
15 [0030]
FIG. 3 schenlatically shows connection states of the cells llOa to 110c and
the series resonance circuit 120 selectively formed by the power storage control
device 130. Specifically, FIG. 3A shows a state in which the two cells llOa and
llOb are connected to the series resonance circuit 120 and the remaining one cell
20 llOc is disconnected from the series resonance circuit 120. FIG. 3B shows a state
in which the two cells llOb and llOc in a different combination from FIG. 3A are
connected to the series resonance circuit 120 and the remaining one cell llOa is
disconnected from the series resonance circuit 120. In short, in the present
modified example, the one cell llOb is connected to the series resonance circuit 120
25 in all the connection states. This case is also included within the scope of the
present disclosure because energy is transferred between the equal numbers of cells
that are the two cells 110a and 110b and another combination of the two cells 110b
and 110c. Other configurations and operations are basically the same as those of
the power storage devices 100 of FIGS. 1 and 2.
30 [0031]
According to the present modified example, the same effect as the power
storage devices 100 of FIGS. 1 and 2 can be exhibited, alid a degree of freed0111 in
the mode of the voltage equalizing process can be improved.
[0032]
<4. Second embodiment>
5 [Device configuration example]
FIG. 4 is an overall diagram schematically showing a configuration example
of a power storage. device 100 of the present embodiment. The power storage
device 100 of the present embodiment has a specified configuration of a power
storage control device 130 with respect to tlie power storage device 100 of FIG. 1.
10 111 other words, the power storage control device 130 is configured to connect a first
cell including at least one cell to a series resonance circuit 120 and then connect a
second cell including the number of cells equal to that of the first cell and having a
lower total voltage than tlie first cell to the series resonance circuit 120. When the
total number of cells 11 Oa and 1 lob is 2, the numbers of first cells and second cells
15 are both 1, as shown in FIG. 4.
[0033]
As an example of a specific configuration for selectively connecting the first
cell and the second cell to the series resonance circuit 120 in order, the power storage
device 100 includes switches 140a, 140b, 140c, and 140d, and cell voltage detection
20 units 150a and 150b as shown in FIG. 4. The power storage control device 130 is
coilfigured to control operations of the switches 140a to 140d to control connection
states of the cells llOa and 1 lob and the series resonance circuit 120.
[0034]
[Switches 140a to 140dI
25 The four switches 140a to 140d are each provided to correspond to the cells
llOa aild llOb as shown in FIG. 4. Specifically, the switches 140a to 140d are
disposed such that two of them respectively correspond to the cells llOa and llOb
and are configured such that every one of them is connected to the positive
electrodes and negative electrodes of the cells 110a and 1 lob.
30 [0035]
More specificallj: the one switch 140a is connected to the positive electrode
of the cell 110a. Another switch 140b is connected to the negative electrode of the
cell 110a. Another switch 140c is connected to the positive electrode of tlie cell
110b. The remaining one switch 140d is connected to the negative electrode of the
cell 11 0b.
5 [0036]
In more detail, the one switch 140a is disposed on a connection line 161
\vliich connects the positive electrode of the cell 1 lOa and a first end 120a of the
series resonance circuit 120. The switch 140a is switched on or off according to a
switch control signal input fsoin the power storage control device 130 to open or
10 close the connection line 161.
[0037]
Another switch 140b is disposed on a connection line 162 which connects
the negative electrode of the cell 110a and a second end 120b of the series resonance
circuit 120. The switch 140b opens or closes the connection line 162 according to a
15 switch control signal input fiom the power storage control device 130.
[0038]
Another s\vitch 140c is disposed on a connection line 163 which connects
the positive electrode of the cell 110b and the first end 120a of the series resonance
circuit 120. The connection line 163 is connected to the other connection line 161
20 running to the first end 120a at a node N1. The switch 140c opens or closes the
connection line 163 according to a switch control signal input from the power storage
control device 130.
[0039]
The remaining one switch 140d is disposed on a connection line 164 which
25 connects the negative electrode of the cell 1 lob and the second end 120b of the series
resonance circuit 120. The connection line 164 is connected to the other contiection
line 162 running to the second end 120b at a node N2. The switch 140d opens or
closes the cotuiection line 164 according to a switch control signal input from tlie
power storage co~~trdoelv ice 130.
30 [0040]
Among the switclies 140a to 140d, a switch connected to the positive
electrode of the first cell will be referred to as a switch on a first positive electrode
side, and a switch connected to the negative electrode of the first cell will be referred
to as a switch on a first negative electrode side hereinbelow. In addition, a switch
corlnected to the positive electrode of the second cell will be referred to as a switch
5 on a second positive electrode side, and a switch connected to the negative electrode
of the second cell will be referred to as a switch 011 a second negative electrode side.
[0041]
A form of the switches 140a to 140d is not limited, and tlie switches 140a to
140d may be configured with, for example, semiconductor elements, or the like.
10 Such a semiconductor element may be a transistor or the like. The transistor may
be a field-effect transistor or the like. The field-effect transistor may be a metaloxide-
semiconductor field-effect transistor (MOSFET) or the like. By employing
the field-effect transistor, power consumption can be suppressed.
[0042]
15 . [Cell voltage detection units 150a and 150bl
The cell voltage detection units 150a and 150b are provided to correspond
to each of the cells llOa and llOb as shown in FIG. 4. The cell voltage detection
units 150a and 150b are each connected to the corresponding cells I 1 Oa and llOb in
parallel. Each of the cell voltage detection units 150a and 150b detects a voltage,
20 i.e., a terminal voltage, of the corresponding cells llOa and 110b, and outputs the
detection result to the power storage control device 130 as cell voltage information.
At this time, tlie cell voltage information may be output in a form in which tlie power
storage control device 130 can specify a cell that corresponds to the cell voltage
infornlation. For example, the cell voltage information may be output toward an
25 input terminal of tlie power storage control device 130 with respect to each of the
cells llOa and 110b, or may be associated with cell number information.
[0043]
An aspect of the cell voltage detection units 150a arid 150b is not limited,
and any of various electronic devices that can detect voltages of the cells llOa and
30 llOb can be employed. The electronic devices may include an integrated circuit
arid tlie like.
[0044]
[Power storage control device 1301
FIG. 5 is a diagram schen~atically showing a configuration example of the
power storage control device 130 of the present etnbodiment. As shown in FIG. 5,
5 the power storage control device 130 has a cell voltage information acquisition unit
13 1 and a switch control unit 132. The cell voltage information acquisition unit 13 1
acquires cell voltage information output from the cell voltage detection units 150a
and 150b. The switch control unit 132 outputs a switch control signal according to
the cell voltage information acquired by the cell voltage information acquisition unit
10 131 to the switches 140a to 140d. Content of the switch control infornlation
includes causing the first cell to be connected to the series resonance circuit 120 and
then causing the second cell to be connected to the series resonance circuit 120.
The switch control signal may be, for exanlple, a gate voltage applied to a fieldeffect
transistor, or the like. The cell voltage information acquisition unit 131 and
15 the switch control unit 132 may be embodied as hardware, software, or both.
[0045]
pevice operation example]
FIG. 6 is a flo\vchart showing an operation exar~lpleo f the power storage
device 100 of the present embodiment. The operation example shown in FIG. 6
20 includes an embodiment of the power storage control method according to the
present disclosure.
[0046]
For the sake of convenience of description, in an initial state of FIG. 6, all
the s~~~itc1h4e0sa to 140d are assumed to be in the off state, i.e., all the cells llOa
25 and llOb are assumed to be disconnected fsom the series resonance circuit 120.
[0047]
Then, first fiom the initial state, the power storage control device 130
decides a first cell and a second cell based on cell voltage infom~ationi n Step 61
(S6l) of FIG. 6. For example, the po~vers torage control device 130 decides the cell
30 llOa as a first cell when cell voltage information fsom the cell voltage detection unit
150a which corresponds to the cell llOa indicates a higher voltage than cell voltage
infortnation from the cell voltage detection unit 150a which corresponds to the cell
1 lob. At the same time, the power storage control device 130 decides the cell llOb
as a second cell.
100481
5 Next, in Step 62 (S62), the power storage control device 130 switches the
switch on the first positive electrode side and the switch on the first negative
electrode side which correspond to the first cell decided in Step 61 (S61) to the on
state. On the other hand, the power storage control device 130 maintains the switch
on the second positive electrode side which corresponds to the second cell decided in
10 Step 61 (S61) and the switch on the second negative electrode side in the off state.
[0049]
' Accordingly, only the first cell is connected to the series resonance circuit
120 by the connection line closed by the switch on the first positive electsode side
and the connection line closed by the switch on the first negative electrode side.
15 Thereby, a current flows fionom the first cell to the series resonance circuit 120 and
energy moves fiom the first cell to the series resonance circuit 120.
[0050]
Next, in Step 63 (S63), the power storage control device 130 switches the
switch on the first positive electrode side and the switch on the first negative
20 electrode side that were switched to the on state in Step 62 (S62) to the off state.
[005 l]
Next, in Step 64 (S64), the power storage control device 130 switches the
switch on the second positive electrode side and the switch on the second negative
electrode side which correspond to the second cell decided in Step 61 (S61) to the 011
25 state. At this titne, the power storage control device 130 maintains the switch on
the first positive electrode side and the switch on the first negative electrode side in
the off state.
[0052]
Accordingly, only the second cell is connected to the series resonance
30 circuit 120 by the connection line closed by the switch on the second positive
electrode side and the connection line closed by the switch on the second negative
electrode side. Thereby, a cusrent flows kom the series resonance circuit 120 to the
second cell and energy that moved to the series resonance circuit 120 in Step 62
(S62) is moved from the series resonance circuit 120 to the second cell.
[0053]
5 Next, in Step 65 (S65), the power storage control device 130 switches the
switch on the second positive electrode side and the switch on the second negative
electrode side that were switched to the on state in Step 64 (S64) to the off state.
Thereafter, the voltage equalizing process ends or the process returns to Step 62
(S62) or Step 64 (S64) if necessary.
10 [0054]
As described above, according to the power storage device 100 of the
present embodiment, after the first cell shifts energy to the series resonance circuit
120, the second cell can take the energy kom the series resonance circuit 120, and
thus a simple and proper voltage equalizing process becomes possible. In addition,
15 connection states of the cells 1lOa and 110b and the series resonance circuit 120 cat1
be controlled with the simple configuration including the switches 140a to 140d.
[OOSS]
4 . First modified example of the second embodiment>
[Device configuration example]
20 FIG. 7 is an overall diagram schematically showing a configuration of a
power storage device 100 of a first modified example of the present embodinlent.
The power storage device 100 of the present modified example has a different cell
disposition form and connection state of cells and a series resonance circuit 120
formed by a power storage control device 130 from the power storage device 100 of
25 FIG. 4. The differences will be described in detail below.
[0056]
In the present modified example, the power storage control device 130 is
configured to cause first cells including a plural it)^ of cells to be connected to the
series resonance circuit 120, and then to cause second cells including a plurality of
30 cells equal in number to the first cells to be connected to the series resonance circuit
120. In addition, the power storage contsol device 130 is configured to select a
plurality of consecutive cells as first cells and to select a plurality of consecutive
cells equal in number to the first cells as second cells. Furthermore, the power
storage control device 130 is configured to cause a cell having a maxi~num voltage
anlong a plurality of serially connected cells to be included in the first cells, and a
5 cell having a minitnum voltage to be incloded in the second cells.
[0057]
As shown in FIG. 7, the power storage device 100 of the present modified
exanlple is obtained by adding two cells llOc and llOd and two cell voltage
detection units 150c and 150d, each corresponding to the cells llOc and 110d, to the
10 configt~ration of FIG. 4. In addition, in the present modified example, four switches
140e, 140f, 140g, and 140h, and four connection lines 165, 166, 167, and 168 are
further added. Specific disposition of the added constituent elements is as shown
below.
[OOSS]
15 The negative electrode of the cell IlOc is connected to the positive electrode
of the cell 110d. The positive electrode of the llOc is connected to the negative
electrode of the cell 11 0b. In other words, in the present modified example, the four
cells 1 lOa to 110d are connected in series in the order of 110a, 11 Oh, 1 1 Oc, and 1 lOd
from the positive electrode terminal P to the negative electrode terminal N of all of
20 the cells.
[0059]
The cell voltage detection units 150c and 150d are connected to the
corresponding cells 1 lOc and 1 lOd in parallel. The cell voltage detection units 150c
and 150d detect voltages of the corresponding cells llOc and llOd and output
25 detection results to the power storage control device 130 as cell voltage information.
[0060]
The switch 140e is disposed on the connection line 165 which connects the
positive electrode of the cell llOc that is in the third position from the positive
electrode terminal P and the first end 120a of the series resonance circuit 120. The
30 connection line 165 is connected to another connection line 163 ru~nling from the
positive electrode of the second cell 1 lob to the first end 120a of the series resonance
circuit 120 at a node N3. The switch 140e opens or closes the connection line 165
according to a switch control signal input Lorn the power storage control device 130.
[0061]
The switch 140f is disposed on the connection line 166 which connects the
5 negative electrode of the third cell llOc and the second end 120b of the series
resollance circuit 120. The connection line 166 is connected to another connection
line 168 running frotn the negative electrode of the fourth cell llOd to the second end
120b of the series resonance circuit 120 at a node N4. In addition, the connection
line 166 is connected to another connection line 164 running fro~n the negative
10 electrode of the second cell llOb to the second end 120b of the series resonance
circuit 120 at a node N5. The switch 140f opens or closes the connection line 166
according to a switch control signal input froni the power storage control device 130.
[0062]
The switch 140g is disposed on the connection line 167 which connects the
15 positive electrode of the fouttli cell llOd and the first end 120a of the series
resonance circuit 120. The connection line 167 is connected to another connection
line 165 running from the positive electrode of the third cell to the first end 120a of
the series resonance circuit 120 at a node N6. Tlie switch 140g opens or closes the
connection line 167 according to a switch control signal input from the power storage
20 control device 130.
[0063]
The switch 140h is disposed on the connection line 168 which connects the
negative electrode of the fourth cell llOd and the second end 120b of the series
resonance circuit 120. Tlie switch 140h opens or closes the connection line 168
25 according to a switch control signal input from the power storage control device 130.
[0064]
[Device operation example]
An operation example of the present tnodified example will be described
with reference to FIG. 7. The operation example below includes an enlbodinlent of
30 the power storage control method according to the present disclosure.
[0065]
For the sake of convenience of description, the power storage col~trodl evice
130 is assumed to detect a voltage of the first cell 11O a to be n~asimuma nd a voltage
of the third cell llOc to be minhnum in an initial state. In addition, all the switches
140a to 140h are assumed to be in the off state.
5 [0066]
In addition, first from the initial state, the power storage control device 130
decides the first cell I lOa and the succeeding second cell 110b as first cells. At the
same time, the power storage control device 130 decides the third cell llOc and the
succeeding fourth cell 110d as second cells.
10 [0067]
Next, the power storage control device 130 switches the switch 140a which
corresponds to the positive electrode of the first cell 110a, i.e., the switch on the first
positive electrode side, to an on state. At the same tirne, the power storage control
device 130 switches the switch 140d which corresponds to the negative electrode of
15 the second cell 110b, i.e., the switch on the first negative electrode side, to an on
state. Through this switching, the positive electrode of the first cell llOa is
connected to the first end 120a of the series resonance circuit 120, and the negative
electrode of the second cell llOb is connected to the second end 120b of the series
resonance circuit 120. Accordingly, energy moves from the first cells constituted
20 by the two consecutive, i.e., adjacent, cells llOa and llOb toward the series
resonance circuit 120.
[0068]
Next, the power storage control device 130 switches the switches 140a and
140d to an off state. At this time, the energy that has moved to the series resonance
25 circuit 120 is retained in the series resonance circuit 120.
loo691
Next, the power storage control device 130 switches the switch 140e which
corresponds to the positive electrode of the third cell 110c, i.e., the s\vitch on the
second positive electrode side, to an on state. At the same time, the power storage
30 control device 130 s\vitches the switch 140h which corresponds to the negative
electrode of the fourth cell 110d, i.e., the s\vitch on the second negative electrode
side, to an on state. Thmugh this switching, the positive electrode of the third cell
llOc is connected to the first end 120a of the series resonance circuit 120, and the
negative electrode of the fourth cell 110d is connected to the second end 120b of the
series resonance circuit 120. Accordingly, energy lnoves ftom the series resonance
5 circuit 120 to the second cells constituted by the two consecutive cells llOc and 110d.
[0070]
In this manner, energy is transferred between cell groups having equal
numbers of cells via the series resonance circuit 120. In the configuration of FIG. 7,
however, transfer of energy between one cell and another cell is also included in the
10 scope of the present disclosure.
[0071]
According to the present modified example, while efficient transfer of
energy is realized with the cells having a nmximun~v oltage selected as the first cells
and the cells having a minimum voltage selected as the second cells, a potential
15 difference between the cells on the polver supply side and the cells on the power
reception side can be reduced more effectively by setting the first cells and second
cells as cell groups. In addition, wiring in the configuration in which adjacent cells
are selected as fust or second cells can be simplified more than in a configuration in
which cells that are not adjacent to each other are selected as first or second cells.
20 [0072]
<6. Third embodiment>
[Device configuration example]
FIG. 8 is an overall diagram schematically showing a configuration example
of a power storage device 100 of the present embodiment. The power storage
25 device 100 of the present embodiment has a specified switch timing of cot~t~ectioonf
cells and a series resonance circuit 120 with respect to the power storage device 100
of FIG. 4. Details thereof will be described below.
[0073]
In the present embodiment, a power storage control device 130 is
30 config~ured to disconnect a first cell fsom the series resonance circuit 120 when a
current flowing in the series resonance circuit 120 after the first cell is connected to
the series resonance circuit 120 becomes OA. In addition, the power storage control
device 130 is configured to disconnect a second cell from the series resonance circuit
120 when a current flowing in the series resonance circuit 120 after the seco~idc ell is
connected to the series resonance circuit 120 beconies OA.
5 [0074]
As shown in FIG. 8, the power storage device 100 has a resonance current
detection unit 170 between a node N1 and the first end 120a of the series resonance
circuit 120. The resonance current detection unit 170 detects a resonance current
flowing to the series resonance circuit 120 and outputs a detection result to the power
10 storage control device 130 as cmrent value information.
[0075]
[Power storage control device 1301
The power storage control device 130 of the present embodiment is one
obtained by adding a current value information acquisition unit 133 to the power
15 storage control device 130 of FIG. 5 as shown in FIG. 9. The cmrent value
information acquisition unit 133 acquires current value information output from the
resonance current detection unit 170. The switch control unit 132 outputs cell
voltage information acquired by the cell voltage information acquisition unit 13 1 and
a switch control signal according to the current value information acquired by the
20 current value information acquisition unit 133 to the switches 140a to 140d.
Content of the switch control signal includes disconnecting a cell that was connected
to the series resonance circuit 120 at the time at which the value of a current flowing
in the series resonance circuit 120 was OA from the series resonance circuit 120.
The current value information acqt~isitionu nit 133 may be embodied as hardware,
25 software, or both.
[0076]
[Device operation example]
An operation of the power storage device 100 of the present embodiment
can be described as an operation of an equivalent circuit of the power storage device
30 100 shown in FIG. 10. In FIG. 10, a switch on a first positive electrode side and a
switch on a first negative electrode side which correspond to a first cell (Celll) are
expressed as one switch SWl. In addition, a switch on a second positive electrode
side and a switch on a second negative electrode side w11ich correspond to a second
cell (Ce112) are expressed as one switch SW2 in FIG. 10. The resonance current
detection unit 170 detects a resonance cursent i running from the first cell to the
5 series resonance circuit 120 in a state in which the first cell is connected to the series
resonance circuit 120, i.e., an on state of the switch SWl. In addition, the
resonance current detection unit 170 detects the resonance current i running from the
series resonance circuit 120 to a second cell in a state in which the second cell is
connected to the series resonance circuit 120, i.e., an on state of the switch SW2.
10 [0077]
[Time charts]
FIG. 11 shows time charts of the equivalent circuit of FIG. 10.
[0078]
In the time charts of FIG. 11, an operation from a time tl at which the
15 resonance current i (see FIG. 11A) is OA is shown. The time tl may be an operation
start time. At the time t l , the resonance current detection unit 170 detects OA, and
the power storage control device 130 switches the switch SWl to an on state as
shown in FIG. 11C based on the detection result of the resonance current detection
unit 170. When the time tl is an operation start time, switching of the switch SWI
20 may be performed at the time tl triggered by decision of a first cell and a second cell.
[0079]
By switching the switch SW1 to the on state, a terminal voltage Vin [V] of
FIG. 10 becomes a voltage El [V] of the first cell, and the resonance current i flows
in a fotward direction fro~n the first cell to the series resonance circuit 120.
25 Accordingly, discharge is performed from the first cell to the series resonance circuit
120. When an amplitude of the resonance current i in the forward direction changes
sinusoidally according to time and reaches a positive peak value ipp (see FIG. 1 lA),
the current becomes OA at a time t2. When the resonance current detection unit 170
detects OA at that time, the power storage control device 130 switches the switch
30 SW1 to an off state and switches the switch SW2 to an on state.
[OOSO]
When the switch SW2 is switched to the on state, the tertninal voltage Vin
[V] becomes a voltage E2 [V] of the second cell and the resonance current i whose
direction has reversed flows into the second cell fionl the series resonance circuit 120.
Accordingly, charge is performed fion~th e series resonance circuit 120 to the second
5 cell. When an amplitude of the resonance cunent i in the reverse direction changes
sinusoidally according to time and reaches a negative peak value ipn (see FIG. 11A),
the current becomes OA at a time t3. When the resonance current detection unit 170
detects OA again at that time, the power storage control device 130 switches the
switch SW2 to an off state and switches the switch SWl to an on state if necessary.
10 [0081]
By repeating the operation of one cycle described above according to
necessity, energy is transferred between the first cell and the second cell via the
series resonance circuit 120, and thereby voltages of the cells are equalized.
[0082]
15 According to the present embodiment, since loss of electricity caused by
opening and closing of the switches can be suppressed, energy can be efficiently
transferred between the equal numbers of cells.
[0083]
17. First modified example of the third embodiment>
20 [Device configuration example]
A power storage device 100 of the present modified example has a different
configuration for switching connectiot~ of a cell and a series resonance circuit 120
fiom the power storage device 100 of FIG. 8. Details thereof will be described
below.
25 [0084]
A power storage control device 130 of the present modified example is
configured to disconnect a first cell fiom the series resonance circuit 120 when a
direction of a current flowing in the series resonance circuit 120 is changed after the
first cell is connected to the series resonance circuit 120. In addition, the power
30 storage control device 130 is configured to disconllect a second cell fiom the series
resonance circuit 120 when a direction of a current flowing in the series resonance
circuit 120 is changed after the second cell is connected to the series resonance
circuit 120.
[OOS5]
FIG. 12 is a circuit diagram showing a configuration example of a resonance
5 current direction detection unit 180 included in the power storage device 100 of the
present modified example. The resonance current direction detection unit 180 is
broadly constituted by a Hall element 181, first and second conlparators 182 and 183,
first and second AND circuits 184 and 185, first and second D-type flip-flops 186
and 187, and first and second NOT circuits 188 and 189.
10 [0086]
The Hall element 18 1 is connected to the non-inverted input terminal (+) of
the first comparator 182 and the inverted input terminal (-) of the second comparator
183. The invested input terminal (-) of the first comparator 182 and the notiinvested
input terminal (+) of the second cotnparator 183 are grounded. The output
15 terminal of the first comparator 182 is connected to the input terminal (D) of the first
D-type flip-flop 186 and the input terminal of the first AND circuit 184. The output
terminal of the second comparator 183 is connected to the input terminal @) of the
second D-type flip-flop 187 and the input terminal of the second AND circuit 185.
The output terminal (Q) of the first D-type flip-flop 186 is connected to the input
20 te~minalo f the first NOT circuit 188. The output terminal (Q) of the second D-type
flip-flop 187 is connected to the input terminal of the second NOT circuit 189. The
output terminal of the first NOT circuit 188 is connected to the input tern~inaol f the
first AND circuit 184. The output terminal of the second NOT circuit 189 is
connected to the input ter~ninal of the second AND circuit 185. The first and
25 second D-type flip-flops 186 and 187 are configured to receive an input of a clock
signal CK having a st~ificientlph igher frequency than a resonance kequency of a
resonance current.
[0087]
An operation example of the resonance current direction detection unit 180
30 will be described with reference to the time charts of FIG. 13.
[OOSS]
First, the resonance current i, is., the direction of tlie resonance current, is
switched fro111 the reverse direction, is., tlie direction ko~nth e series resonance
circuit 120 to a cell, to the forward direction, i.e., the direction from a cell to the
series resonance circuit 120, at a tinie tl as shown in FIG. 13A. In other words, the
5 value of tlie resonance current i is switched from negative to positive at the time tl.
[0089]
Accordingly, when the first comparator 182 receives an input of an
electrical signal corresponditig to the resonance current i in the forward direction
from tlie I-Iall element 181, a value of the lion-inverted input terminal (+) becomes
10 higher than a value of the inverted input terminal (-). As a result, as shown in FIG.
13B, the output of the first comparator 182 becomes "High" (indicated by H in the
drawing), i.e., "1," at the time tl.
[0090]
On the other hand, when the second comparator 183 receives an input of an
15 electrical signal corresponding to the resonance current i of the fonvard direction
from the Hall element 181, a value of the tion-inverted input terminal (+) becomes
lower than a value oft he inve~tedin put terminal (-). Accordingly, as shown in FIG.
13C, the output of the second comparator 183 becomes "Low" (indicated by L in the
drawing), i.e., "0," at the time tl.
20 [0091]
While the output "High" of the first comparator 182 is input to the D
terminal of the first D-type flip-flop 186, the input value of the clock signal is "Low"
(which is not illustrated), and thus the output Q of the first D-type flip-flop 186 of the
previous status is maintained. Accordingly, the output of the first D-type flip-flop
25 186 (the first D-type FF) becomes "Low" at the time tl as shown in FIG. 13D.
[00921
On the other hand, while the output "Low" fro111 the second comparator 183
is input to the D terminal of the second D-type flip-flop 187, tlie input value of the
clock signal is "Low" (which is not illustrated), and thus the previous status of the
30 output Q of the second D-type flip-flop 187 is maintained. Accorditigly, the output
of tlie second D-type flip-flop 187 (the second D-type FF) becomes "High" at the
time tl as shown in FIG. 13E.
[0093]
The output "Higll" of the first comparator 182 and tlie output "Higli" of the
first NOT circuit I88 which negates the output of the first D-type flip-flop 186 are
5 input to the first AND circuit 184. Accordingly, the output of the first AND circuit
184, i.e., logical product, becomes "Higli" at the time tl as shown in FIG. 13F.
[0094]
On the other hand, the output "Lo\vn of the second comparator 183 and the
output "Low" of the second NOT circuit 189 which negates the output of the second
10 D-type flip-flop 187 are input to the second AND circuit 185. Accordingly, the
output of the second AND circuit 185 becomes "Low" at the time tl as shown in FIG.
13G.
[0095]
As described above, the resonance current direction detection unit 180
15 detects that the direction of the current at the time tl is the fo~wardd irection based
on the output "High" of the first AND circuit 184 and the output "Low" of the
second AND circuit 185. Then, the resonance current direction detection unit 180
outputs the detection result to the power storage control device 130.
[0096]
20 Next, at the time t2 at wl~icha slight time has elapsed fiom the time tl, the
clock signal input to the first and second D-type flip-flops 186 and 187 is switched
fiom "Low" to "Higli," although it is not illustrated. Accordingly, the output of tlie
first D-type flip-flop 186 is switched to "High" that is an input value of the D
tern~inala s shown in FIG. 13D. In addition, the output of the second D-type flip-
25 flop 187 is switched to "Low" that is an input value of the D terminal as shown in
FIG. 13E. Accordingly, the output of the first AND circuit 184 is switched to
"Low" at the time t2. On the other hand, the output of the second AND circuit 185
remains "Lo~v."
[0097]
30 Next, the direction of the resonance current i is switched fiom the forward
direction to the reverse direction at a time t3. In the operation of the resonance
current direction detection unit 180, "High" and "LOIV" are reversed from those at
the time tl. In other words, it is detected that the direction of the current is the
reverse direction at the time t3 based on the ootp11t "Low" of the first AND circuit
184 and the output "High" of the second AND circuit 185.
5 [0098]
Note that a configuration of the resonance current direction detection unit
180 is not limited to that shown in FIG. 12.
[0099]
[Device operation example]
10 FIG. 14 is a flo\vcl~art showing an operation exanlple of the power storage
device 100 of the present embodiment. The operation example shown in FIG. 14
includes an embodiment of the power storage control method according to the
present disclosure.
[OlOO]
15 The operation example of FIG. 14 includes the following differences from
FIG. 6. That is, in FIG. 14, Step 141 (S141) and Step 142 (S142) are executed
between Step 62 (S62) and Step 63 (S63). In addition, in FIG. 14, Step 143 (S143)
to Step 146 (S146) are executed after Step 64 (S64).
[OlOI]
20 Specifically, in Step 141 (S141), the resonance current direction detection
unit 180 detects a direction of the resonance current i.
[O 1021
In Step 142 (S142), the power storage control device 130 determines
whether or not iSO, i.e., the direction of the resonance current i has changed, based
25 on the detection result of Step 141 (S141). Then, \vhen a positive deternlination
result is obtained in Step 142 (S142), the power storage control device proceeds to
Step 63 (S63), and when a negative deter~nination result is obtained, the power
storage control device returns to Step 141 (S141).
[0103]
30 In Step 143 (S143), the resonance current direction detection unit 180
detects a direction of the resonance ctnsent i.
[0 1041
In Step 144 (S144), the power storage control device 130 determines
whether or not i10, i.e., the direction of the resonance cur~cnit has changed, based
on the detection result of Step 143 (S143). Then, when a positive deter~nination
5 result is obtained in Step 144 (S144), tlie power storage cotltrol device proceeds to
Step 145 (S145), and when a negative dcternlination result is obtained, the power
storage control device returns to Step 143 (S143).
[0 1051
In Step 145 (S145), the power storage control device 130 determines
10 whether the voltage equalizing process should be finished. This determination can
be made based on, for example, whether or not an external control signal is input to
the powcr storage control device 130, whether a voltage difference between a first
cell and a second cell is within prescribed values, or the like. Then, when a positive
determination result is obtained in Step 145 (S145), the power storage control device
15 proceeds to Step 65 (S65), and when a negative determination result is obtained, the
power storage control device retur~~tos S tep 146 (S146).
[0 1061
In Step 146 (S146), the power storage control device 130 switches the
switch on the second positive electrode side and the switch on the second negative
20 electrode side to an off state, and proceeds to Step 62 (S62).
[0107]
As long as the voltage equalizing process is repeated a plurality of times, i.e.,
a plurality of cycles, when necessary, and energy is transferred between cells equal in
number in each cycle, transfer of energy between cells of which the numbers are
25 different in different cycles belongs to the scope of the present disclosure.
[OIOS]
According to the powcr storage device 100 of the present modified example,
a timing at which nloven~ento f energy between the first cell or the second cell and
the series resonance circuit 120 is deemed to have been completed can be detected
30 using a simple method such as one with respect to a change of a direction of a current,
and the cell can be disconnected fion~th e series resonance circnit 120. Accordingl~:
a more rapid voltage equalizing process is possible at a low cost. In addition, the
resonance current direction detection unit 180 can detect a direction of a resonance
current rapidly and accurately.
[0109]
5 4 . Fourth embodiment>
[Device configuration example]
A power storage device 100 of the present embodiment has a different
tinling at which connection of a cell and a series resonance circuit 120 is switched
from the power storage devices 100 of FIGS. 8 and 12. Details thereof will be
10 described below.
[OllO]
A power storage control device 130 of the present embodiment is configured
to disconnect a second cell from the series resonance circuit 120 and then to maintain
a disconnection state of all cells from the series resonance circuit 120 during a set
15 period (hereinafter referred to as a waiting period). In addition, the power storage
control device 130 is configured to determine whether or not transfer of energy, i.e., a
voltage equalizing process, should be finished based on a voltage of a cell during the
waiting period.
[Olll]
20 A form of the waiting period is not limited, and a proper time can be set for
the power storage control device 130 for measurement of a voltage of a cell and
determination of appropriateness of the voltage equalizing process. The waiting
time may be changeable.
[0112]
25 [Device operation example]
[Time charts]
FIG. 15 is a diagram showing an operation example of the power storage
device 100 of the present embodiment using similar time charts to those of FIG. 11.
[0113]
30 In the time charts of FIG. 15, after the switch SW2 is switched off at the
time t3, the switch SWI is switched on at a time t4 at \vliich a waiting time T has
elapsed therefrom. During the waitiug time T, the power storage control device 130
determines whether the voltage equalizing process should be finished based on a
detection result of a cell voltage. Since the resonance cunent i is OA during the
waiting time T, the cell voltage measured during the waiting time T has an accurate
5 value that is not affected by internal impedance of the cell. If appropriateness of
finishing the voltage equalizing process is determined based on such an accurate cell
voltage, a proper determination result can be obtained. Note that, vv11en the voltage
equalizing process is determined to be finished during the waiting period T, the
power storage control device 130 does not switch the switch SWI on at the time t4.
10 [0114]
[Flowchart]
FIG. 16 is a diagram showing the operation example of the power storage
device 100 of the present embodiment in a flowchart. The flowchart of FIG. 16 has
a different process after Step 144 (S144) fro111 the flowchart of FIG. 14. Specifically,
15 in FIG. 16, after a positive determination result is obtained in Step 144 (S144), Step
65 (S65), Step 161 (S 161), and Step 162 (S 162) are executed in order.
[0115]
Specifically, in Step 161 (S161), the power storage control device 130 waits
for next connection of a first cell to the series resonance circuit 120 for the waiting
20 period and measures a cell voltage during the waiting period. The cell voltage
detection units 150a and 150b shown in FIG. 4 may be caused to measure the cell
voltage.
[0116]
In Step 162 (S162), the power storage control device 130 determines
25 whether or not the voltage equalizing process should be finished based on the
measurement result of the cell voltage in Step 161 (S161). Then, when a positive
determination result is obtained in Step 162 (S162), the power storage control device
finishes the process, and when a negative determination result is obtained, the power
storage control device proceeds to Step 62 (S62).
30 [0117]
According to the present eembodiment, appropriateness of finishing the
voltage equalizing process can be properly determined based on an accurate cell
voltage measured during a waiting period, and fi~rthel; the voltage equalizing process
can be perfornled more suitably.
[0118]
5 <9. First nlodified example of the fourth emnboditnent>
[Device configuration example]
A power storage device 100 of the present embodiment has a different
tinling at which connection of a cell and a series resonance circuit 120 is switched
from the power storage device 100 of FIGS. 15 and 16. Details thereof will be
10 described below.
[0119]
Apower storage contsol device 130 of the present embodiment is configured
to maintain a disconnection state of all cells from the series resonance circuit 120
during a waiting period even after a first cell is disconnected from the series
15 resonance circuit 120, and to determine appropriateness of finishing a voltage
equalizing process during the waiting period. This waiting period may also be set
to be changeable with respect to the power storage control device 130.
[O 1201
[Device operation exanlple]
20 [Titne charts]
FIG. 17 includes time charts showing an operation example of the power
storage device 100 of the present embodiment. In the time charis of FIG. 17, after
the switch SW1 is switched off at the time t2, the switch SW2 is switched on at the
time t3 at which a second waiting period T2 has elapsed. In addition, in the time
25 charts of FIG. 17, after the switch SW2 is switched off at the time t4, the switch SWl
is switched on at a time t5 at which a first waiting period T1 has elapsed. During
the waiting periods T1 and T2, tlie power storage control device 130 determines
whether or not the voltage equalizing process should be finished based on a detection
result of a cell voltage. The waiting periods T1 and T2 may be the satne as or
30 different fsom each other.
[0121]
[Flowchart]
FIG. 18 is a flowchart showing the operation example of the pourer storage
device 100 of the present embodiment. The flowchart of FIG. 18 is different f's0111
the flowchart of FIG. 16 in that Step 181 (S181) and Step 182 (S182) are executed
5 between Step 63 (S63) and Step 64 (S64).
[O 1221
Specifically, in Step 181 (Slgl), the power storage control device 130 waits
for connection of a second cell to the series resonance circuit 120 for the second
waiting period and measures a cell voltage during the second waiting period.
10 [0123]
In Step 182 (S182), the power storage control device 130 determines
whether or not the voltage equalizing process should be finished based on the
measurement result of the cell voltage of Step 181 (S181). Then, when a positive
determination result is obtained in Step 182 (S182), the power storage control device
15 finishes the process, and when a negative determination result is obtained, the power
storage control device proceeds to Step 64 (S64).
[0 1 241
According to the power storage device 100 of the present modified example,
it is possible to increase chances of accurately determining appropriateness of
20 finishing the voltage equalizing process.
[0125]
4 0 . Fifth embodiment>
[Device configuration example]
FIG 19 is a diagram showing a configuration example of a series resonance
25 circuit 120 of a power storage device 100 of the present embodiment. The series
resonance circuit 120 of the present embodiment is different eon1 the series
resonance circuits 120 of the first to fourth embodiments in that it has a resistatlce
123, in addition to a reactor 121 and a capacitor 122. In other words, the series
resonance circuit 120 of the present embodiment is an RLC series resonance circuit.
30 [0126]
[Device operation example]
An operation example of the power storage device 100 of the present
embodiment can be described as an operation exanlple of an equivalent circuit of the
power storage device 100 shown in FIG. 20.
[O 1271
5 With respect to the equivalent circuit of FIG. 20, the peak value Ipeak [A] of
a resonanee eurrent i flowing in a first eell (Celll) and a seeolld cell (Ce112) is a value
indicated by the following expression ( 1 ) .
Ipeak = (El-E2)/(2xR) ( 1 )
In the expression ( I ) , El represents a voltage [V] of the first cell. E2
10 represents a voltage [V] of the seeond eell. R represents a value [a] of the
resistance 123.
[0128]
As the expression ( 1 ) indicates, the peak value Ipeak varies aceording to a
value of the resistance 123, and as a resistance value increases, a smaller peak value
15 Ipeak is obtained.
[0129]
The resonanee eurrent i [A] is a value indicated by the following expression
(2).
i = {(El-E2)1(2xR)}xsinwot (2)
20 In the expression (2), wo represents a resonance angle frequency [radls]
expressed by the following expression (3).
0 0 = ~/(Lxc)~" (3)
In the expression (3), L represents a selfrinduetanee [HI of the reactor 121,
and C represents electrostatic capacitance [F] of the capacitor 122.
25 Note that a resonance frequency fo is od2n from the expression (3).
[0130]
In the expression (2), in a first-half cycle, i.e., in a period in which mot is 0
to n [rad], discharge is performed from the first eell to the series resonanee circuit
120. On the other hand, in a second-half cycle, i.e., in a period in which mot is n to
30 2n [rad], charge is performed fiom the series resonanee circuit 120 to the seeond eell.
The average discharge current Idis [A] of the first-half cycle and the average charge
cu~~enIcth a [A] of the second-half cycle can be obtained by integrating the
expression (2) for each half cycle of a resonance frequency and averaging the results.
Specifically, the average discharge current Idis and the average charge cu~sentI cha
have a value expressed by the following expression (4).
5 Icha = Idis= (El-E2)/(nxR) (4)
If connection of a cell and the series resonance circuit 120 is switched at a
timing at which i is OA or a timing at ~ ~ ~ Ith~e idcirehc tion of i changes, electric charge
corresponding to the expression (4) can be supplied from the first cell to the second
cell.
10 [0131]
According to the power storage device 100 of the present embodiment,
since the peak current Ipeak can be suppressed by the resistance 123, a burden
imposed on a cell can be more effectively reduced.
[0132]
15 i l l . First modified example of the fifth embodiment>
FIG. 21 is a diagram showing a main part of a power storage device 100 of
the present modified example. The power storage device 100 of the present
modified example is configured such that a power storage control device 130 detects
the direction and ~nagnitude of a culsent flowing in a series resonance circuit 120
20 based on a potential difference of both ends of a resistance 123 of the series
resonance circuit 120. The potential difference of both ends of the resistance 123
may be detected by a voltage detection unit 190.
[0133]
According to the power storage device 100 of the present modified example,
25 costs can be reduced more even when the resonance cu~sendt etection unit 170 of FIG.
8 and the resonance cusrent direction detection unit 180 of FIG. 12 are provided to
detect a resonance current.
[0134]
4 2 . Second modified example of the fifth embodinlent>
30 FIG 22 is a diagram showing a series resonance circuit 120 of a po\ver
storage device 100 of the present modified example. The series resonance circuit
120 of FIG. 22 is different from the series resonance circuit 120 of FIG. 19 in that a
resistance 123 is a parasitic resistance. The parasitic resistance may be a parasitic
resistance of at least one of a reactor 121, a circuit wire, and a switch. According to
the present modified example, a peak value of a resonance current can be suppressed
5 using a small number of parts.
[0135]
4 3 . Sixth embodiment>
[Device configuration example]
A power storage device 100 of the present embodiment has a different
10 configuration for switching co~lnectiono f a cell and a series resonance circuit 120
from the power storage devices 100 of the first to fifth embodiments. Details
thereof will be described below.
[0136]
A power storage control device 130 of the present modified example is
15 configured to switch connection of the series resonance circuit 120 and a cell using a
resonance frequency of the series resonance circuit 120.
[0137]
Here, like the period between the time tl and the time t2 of FIG. 11, a period
from connection of one cell to the series resonance circuit 120 to connection of
20 another cell replacing the one cell to the series resonance circuit 120 is defined as a
connection switching cycle. Since the connection switching cycle is a half cycle of
a resonance cycle of the series resonance circuit 120, it is indicated with ~ ( L x c ) ' ~
[s]. The power storage control device 130 of the present modified example can be
said to be configured to switch connection of the series resonance circuit 120 and a
25 cell in each connection switching cycle.
[0138]
The power storage control device 130 may be configured to store
information such as a resonance fkequency and a connection switching cycle, and to
operate by computing a connectiou switching timing based on the stored information.
30 [0139]
[Device operation example]
FIG. 23 is a flowchart showing an operation example of the power storage
device 100 of the present enlbodiment. In FIG, 23, first, the power storage control
device 130 connects a cell on a power supply side to the series resonance circuit 120
in Step 231 (S23 1).
5 [0140]
Next, in Step 232 (S232), the power storage control device 130 deternlines
whether or not a connection switching timing based on a resonance frequency of the
series resonance circuit 120 has arrived. Then, when a positive determination result
is obtained in Step 232 (S232), the power storage control device proceeds to Step
10 233 (S233), and when a negative determination result is obtained, the power storage
control device returns to Step 232 (S232).
[0141]
Next, in Step 233 (S233), the powver storage control device 130 disconnects
the cell on the power supply side fiom the series resonance circuit 120.
15 [0142]
Next, in Step 234 (S234), the power storage control device 130 connects a
cell on a power reception side to the series resonance circuit 120.
[0 1431
Next, in Step 235 (S235), the power storage control device 130 determines
20 whether or not a cont~ections witching timing based on a resonance fsequency of the
series resonance circuit 120 has arrived. Then, when a positive determination result
is obtained in Step 235 (S235), the power storage control device proceeds to Step
236 (S236), and when a negative determination result is obtained, the power storage
control device repeats Step 235 (S235).
25 [0144]
Next, in Step 236 (S236), the powver storage control device 130 disconnects
the cell on the powver reception side from the series resonance circuit 120.
[0145]
Then, in Step 237 (S237), the pom7er storage control device 130 finishes this
30 voltage equalizing process when the process should be finished, and returns to Step
231 (S231) when the voltage equalizing process is to be continued. The
deter~ninationo f \vhetller to finish the voltage equalizing process may be perfomled
before Step 237 (S237).
[0146]
According to the power storage device 100 of the present embodiment,
5 connection of a.cell can be switched at a timing proper for transfer of energy, with 110
need to monitor a current flowing in the series resonance circuit 120.
[0147]
114. Seventh embodiment>
The power storage device 100 of the present embodiment shows a different
10 resonance frequency of the series resonance circuit 120 from tlie power storage
devices 100 of the first to sixth embodiments.
[0148]
Specifically, the resonance frequency of the series resonance circuit 120
according to the present embodiment is a frequency when an imaginaly number
15 component in a Cole-Cole plot of internal impedance of cells measured using an AC
impedance method is 0.
[0 1491
Here, in the AC impedance method, the internal impedance of each
frequency is measured while a frequency is changed by applying an alternate current
20 to cells. The Cole-Cole plot is one method for illustrating a measurement result of
the AC impedance method. In the Cole-Cole plot, tlie internal impedance of cells
for each frequency obtained using the AC impedance method is plotted on a complex
plane whose horizontal axis represents real number components of internal
impedance and whose ve~ticala xis represents imaginary number components of the
25 internal impedance.
[0150]
An example of the Cole-Cole plot is shown in FIG. 24. The horizontal axis
of FIG. 24 represents the real part of internal impedance of a cell, and the vertical
axis of FIG. 24 represents the imaginary part of the internal impedance of the cell.
30 In FIG. 24, the frequency when an imaginary component of the internal impedance
becomes 0 is fnlin [Hz]. In this case, the series resonance circuit 120 may be
designed so that finin serves as a resonance frequency. Specifically, it is preferable
to select the self-inductance L of the reactor 121 and the electrostatic capacitance C
of the capacitor 122 in advance to satisfy fmin = 1 / { 2 n x ( ~ x ~ ) ' ~N}o.t e that finin
may be a value of 1 k [Hz] to 10k [Hz].
5 [0151]
In the power storage device 100 of the present enibodiment, internal
ilnpedance of a cell becomes tlie minimum with respect to a current flowing between
a cell and the series resonance circuit 120. Therefore, energy can be eficiently
transferred.
10 [0152]
4 5 . First tnodified example of the seventh embodiment>
A power storage device 100 of the present modified exanlple bas a different
setting of a resonance frequency of series resonance circuit 120 from the power
storage device 100 described with reference to FIG. 24.
15 [0153]
Examples of Cole-Cole plots for describing the power storage device 100 of
the present tnodified example are schematically shown in FIG. 25. The horizontal
axis Z' of FIG. 25 represents the real part of internal impedance of cells and the
vertical axis 2" of FIG. 25 represents the imaginaly past of the internal impedance of
20 the cells. In FIG. 25, tlie Cole-Cole plots of respective states of charge (SOC) [%I
are shown as examples of charge ratios of cells. The Cole-Cole plots of FIG. 25 are
plots based on measurement results of the internal impedance of the cells by a
frequency response analyzer (FRA). Specific numerical values in FIG. 25 are
merely examples, and do not limit the scope of the present disclosure.
25 [0154]
As shown in FIG. 25, a Cole-Cole plot may be different according to SOC.
When the frequency fmin when the imaginary nuniber conlponent in the Cole-Cole
plot is 0 is different according to SOC, fmin is obtained for each SOC and a
resonance frequency of the series resonance circuit 120 may be set con~prcliensively
30 taking obtained finin of each SOC into consideration. For example, the series
resonance circuit 120 may be designed such that the average value of fmin of the
SOC is obtained and the average value is set to the resonance frequency.
[0155]
According to the present modified example, energy can be efficiently
transferred in consideration of a changing SOC.
6 [0156]
4 6 . Eighth embodime~it>
A power storage device 100 of the present etnbodiment has a specific cell
with respect to the power storage devices 100 of the first to seventh e~nbodiments.
[0157]
10 Specifically, a cell of the present embodiment has a discharge characteristic
in which a change of a voltage is 0.25 V or lower it1 a series of sections spanning
50% or more of the section of the charge ratio of 0% to 100%.
[0158]
As an example of such a discharge characteristic, a discharge curve obtained
15 when a lithium ion secondary battery of which a material of the positive electrode is
olivine-type iron phosphate is discharged at 1C is shown in FIG. 26. With respect to
the discharge curve of FIG. 26, the horizontal axis represents SOC [%I as an example
of a discharge ratio, and the vertical axis represents terminal voltages [V] of cells.
In the discharge curve of FIG. 26, a change of voltage is 0.25 V or lower in a series
20 of sectior~s spanning 50% or more of the section of the discharge ratio of 0% to
100%. More specifically, the discharge curve of FIG. 26 shows a change of voltage
of about 0.1 V in the section of the discharge ratio of 20% to 90%. Although the
discharge curve of FIG. 26 shows a significant voltage drop attributable to internal
resistance itnmediately after the start of discharge, it continuously shows a flat
25 characteristic thereafter, and thus unevenness in voltage within a battery pack
configured in serial connection becomes small. The cells are not limited to lithiu~n
ion seco~idaryb atteries that use olivine-type iron phosphate.
[0159]
Here, the power storage device 100 has relatively even temperature
30 distribution therein and a load current fluctuates little in co~nparisot~oi an automobile
or the like, and thus unevenness of voltages between cells is small. Therefore, in
thc power storage device 100, it is desirable in the voltage equalizing process to
secure cell balance with a low current without waste, rather than rapidly resolving
unevenness of voltages between cells using a high cunent. In addition, if a cell
having a flat discharge characteristic as in the present embodinlent is applied,
5 effectiveness of a voltage equalizing process can be secured with a low current.
[0 1601
The above-described embodiments and modified examples may be
appropriately combined.
[0161]
10 Effects described in the embodiments and modified exan~ples are merely
illustrative and are not limitative, and other effects may be exhibited. The present
disclosure may exhibit any one of a plurality of effects described in the embodiments
and modified examples.
[0 1621
15 Additionally, the present technology may also be configured as below.
(1)
A power storage device including:
a plurality of cells which are connected in series;
a series resonance circuit configured to include a reactor and a capacitor;
20 and
a power storage control device configured to control a connection state of
the cells and the series resonance circuit,
wherein the power storage control device causes energy to be transferred
between equal numbers of cells via the series resonance circuit.
25 (2)
The power storage device according to (I), wherein, after the power storage
control device connects first cells including at least one cell to the series resonance
circuit, the power storage control device connects second cells which include cells
equal in number to the first cells and have a lower total voltage than the first cells to
30 the series resonance circuit.
(3)
The power storage device according to (2), wherein the power storage
control device selects a plurality of consecutive cells as the first cells, and selects
consecutive cells equal in liumber to the first cells as the second cells.
(4)
5 The power storage device according to (2) or (3), wherein, when the first
cells are connected to the series resonance circuit and then the direction of a current
flowing in the series resonance circuit changes, the power storage control device
disconnects the first cells from the series resonance circuit.
(5)
10 The power storage device according to (4), wherein, when the second cells
are connected to the series resonance circuit and then the direction of a culxent
flowing in the series resonance circuit changes, the power storage control device
disconnects the second cells from the series resonance circuit.
(6)
15 The power storage device according to (5), wherein the power storage
control device maintains a state in which all the cells are disconnected from the
series resonance circuit during a set period after the first and/or second cells are
disconnected from the series resonance circuit, and determines whether or not
transfer of energy is to be finished based on a voltage of the cells during the set
20 period.
(7)
The power storage device according to any one of (1) and (4) to (6),
wherein the series resonance circuit includes a resistance, and
wherein the power storage control device detects the direction of a current
25 flowing in the series resonance circuit based on a potential difference of both ends of
the resistance.
(8)
The power storage device according to any one of (1) to (3), wherein tlie
power storage control device switches connection of the series resonance circuit and
30 the cells using a resonance frequency of the series resonance circuit.
(9)
The power storage device according to any one of ( 1 ) to (8), wherein a
resonance frequency of the series resonance circuit is a frequency when an imaginary
component in a Cole-Cole plot of internal impedances of the cells measured using an
AC impedance method becomes 0.
5 (10)
The power storage device according to any one of (2) to (9), wherein the
power storage control device causes a cell having a maximum voltage to be included
in the first cells.
( 1 1 )
10 The power storage device according to any one of (2) to (lo), wherein the
power storage control device causes a cell having a minimum voltage to be included
in the second cells.
(12)
The power storage device according to any one of ( I ) to ( l l ) , fiuther
15 including:
a switch cotfigured to connect or disconnect the cells and the series
resonance circuit,
wherein the power storage control device controls a connection state of the
cells and the series resonance circuit by controlling an operation of the switch.
20 (13)
The power storage device according to any one of ( I ) to (12), wherein the
cells have a discharge characteristic that a change of a voltage is 0.25 V or lower in a
series of sections spanning 50% or more of a section of a charge ratio of 0% to 100%.
(14)
25 A power storage program for causing a conlputer to functions as a means of
controlling a connection state of a plurality of cells which are connected in series and
a series resonance circuit which includes a reactor and a capacitor and causing
energy to be transferred between equal nulnbers of cells via the series resonance
circuit.
Reference Signs List
[0 1631
100 power storage device
110a, 1lOb cell
120 series resonance circuit
5 121 reactor
122 capacitor
130 power storage control device

CLAIMS
Claim 1
A power storage device comnprising:
a plurality of cells which are co~~necteind series;
a series resonance circuit co~~figuretod include a reactor and a capacitor;
and
a power storage control device configured to cor~trol a connection state of
the cells and the series resonance circuit,
wherein the power storage control device causes energy to be transferred
10 between equal numbers of cells via the series resonance circuit.
Claim 2
The power storage device according to claim 1, \vherein, after the power
storage control device connects first cells including at least one cell to the series
16 resonance circuit, the power storage control device connects second cells which
include cells equal in number to the first cells and have a lower total voltage than the
first cells to the series resonance circuit.
Claim 3
20 The power storage device according to claim 2, wherein the power storage
control device selects a plurality of consecutive cells as the first cells, and selects
consect~tivec ells eqtial in number to the first cells as the second cells.
Claitn 4
25 The power storage device according to claimn 2, wherein, when the first cells
are connected to the series resonance circuit and then the direction of a current
flowing in the series resonance circuit changes, the power storage control device
disconnects the first cells from the series resonance circuit.
30 Claim 5
The power storage device according to claim 4, wherein, wilen the second
cells are connected to the series resonance circuit and then the direction of a current
flowing in the series resonance circuit changes, the power storage control device
disconnects the second cells from the series resonance circuit.
5 Claim 6
The power storage device according to claim 5, wherein tile po~ver storage
control device nlaintains a state in which all the cells are disconnected from the
series resonance circuit during a set period after the first andlor second cells are
disconnected !?om the series resonance circuit, and determines wlletller or not
10 transfer of energy is to be finished based on a voltage of the cells during the set
period.
Claim 7
The power storage device according to claim 1,
15 wherein the series resonance circuit includes a resistance, and
wherein the power storage control device detects the direction of a curretit
flowit~gin the series resonance circuit based on a potential difference of both ends of
tlie resistance.
20 Claim 8
The power storage device according to claim 1, wllerein the power storage
control device switches connection of the series resonance circuit and the cells using
a resonance fiequency of the series resonance circuit.
25 Claim 9
The power storage device according to claim 1, wherein a resonance
frequency of the series resonance circuit is a fiequency wllien an imaginary
component in a Cole-Cole plot of internal impedances of the cells measured using an
AC impedance method becomes 0.
30
Claitn 10
The power storage device according to claim 2, wherein the power storage
control device causes a cell havi~ig a lnaxinlum voltage to be included in the first
cells.
5 Claim 11
The power storage device according to claim 10, wherein the power storage
control device causes a cell having a minimum voltage to be included in the second
cells.
10 Claim 12
The power storage device according to claim 2, further comprising:
a switch configured to connect or disconuect the cells and the series
resonance circuit,
wherein the power storage control device controls a connection state of the
15 cells and the series resonance circuit by controllitlg an operation of the switch.
Claim 13
The power storage device according to claim 2, wherein the cells have a
discharge characteristic that a change of a voltage is 0.25 V or lower in a series of
20 sections spanning 50% or more of a section of a charge ratio of 0% to 100%.
Claim 14
A power storage control device configured to control a connectioll state of a
plurality of cells which are connected in series and a series resonance circuit wluch
25 includes a reactor and a capacitor, and to cause energy to be transferred between
equal numbers of cells via the series resonance circuit.
Claim 15
A power storage control method of a control device which controls a
30 connection state of a plurality of cells which are connected in series and a series
resonance circuit which includes a reactor and a capacitor to cause energy to be
transferrect bet\veen equal iiu~lll-rerosf cells via the series resollance circuit.