U.S. patent application number 14/173771 was filed with the patent office on 2014-06-05 for power supply apparatus and power supply method.
The applicant listed for this patent is Furukawa Automotive Systems Inc., Furukawa Electric Co., Ltd.. Invention is credited to Shinichi NOMOTO.
Application Number | 20140152262 14/173771 |
Document ID | / |
Family ID | 47424017 |
Filed Date | 2014-06-05 |
United States Patent
Application |
20140152262 |
Kind Code |
A1 |
NOMOTO; Shinichi |
June 5, 2014 |
POWER SUPPLY APPARATUS AND POWER SUPPLY METHOD
Abstract
A power supply apparatus is provided that has a plurality of
secondary batteries connected in series, outputs a composite
voltage of all of the secondary batteries, and outputs an output of
a part of the secondary batteries as a partial voltage. The power
supply apparatus includes a detecting unit that detects states of
the secondary batteries, a changing unit that changes an order of
series connection of the plurality of secondary batteries based on
a detection result of the detecting unit in such a manner that the
partial voltage is outputted from a secondary battery that is in a
relatively good state.
Inventors: |
NOMOTO; Shinichi; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Furukawa Automotive Systems Inc.
Furukawa Electric Co., Ltd. |
Shiga
Tokyo |
|
JP
JP |
|
|
Family ID: |
47424017 |
Appl. No.: |
14/173771 |
Filed: |
February 5, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/JP2012/065989 |
Jun 21, 2012 |
|
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14173771 |
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Current U.S.
Class: |
320/118 ;
320/126 |
Current CPC
Class: |
B60L 1/00 20130101; H01M
10/482 20130101; B60L 2240/547 20130101; H01M 10/441 20130101; H02J
7/0063 20130101; H02J 1/00 20130101; B60L 58/19 20190201; H02J
7/0024 20130101; H02J 7/0016 20130101; H02J 7/34 20130101; Y02T
10/70 20130101; H02J 7/342 20200101; B60L 58/22 20190201; Y02E
60/10 20130101 |
Class at
Publication: |
320/118 ;
320/126 |
International
Class: |
H02J 7/00 20060101
H02J007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2011 |
JP |
2011-145149 |
Claims
1. A power supply apparatus that has a plurality of secondary
batteries connected in series, outputs a composite voltage of all
of the secondary batteries, and outputs an output of a part of the
secondary batteries as a partial voltage, the power supply
apparatus comprising: a detecting unit that detects states of the
secondary batteries; and a changing unit that changes an order of
series connection of the plurality of secondary batteries based on
a detection result of the detecting unit in such a manner that the
partial voltage is outputted from a secondary battery that is in a
relatively good state.
2. The power supply apparatus according to claim 1, wherein the
power supply apparatus has two secondary batteries; the power
supply apparatus outputs a composite voltage of terminal voltages
of the two secondary batteries and a terminal voltage of a
secondary battery connected to a ground side as a partial voltage;
the detecting unit detects states of the two secondary batteries;
and the changing unit changes an order of the series connection in
such a manner that a secondary battery that is in a relatively good
state, which has been detected by the detecting unit, is connected
to a ground side.
3. The power supply apparatus according to claim 2, wherein the
changing unit has four switches each having a single common
terminal, a first selective terminal and a second selective
terminal; a positive pole and a negative pole of each of the two
secondary batteries are connected to the respective common
terminals of the four switches; respective first selective
terminals of the four switches are connected with one another, the
respective first selective terminals being a terminal that outputs
the partial voltage; respective second selective terminals of two
switches connected to the positive pole through the respective
common terminals are connected with each other, the respective
second selective terminals being a terminal that outputs the
composite voltage; respective second selective terminals of the two
switches connected to the negative pole through the respective
common terminals are connected with each other, the respective
second selective terminals being a terminal that is connected to a
ground; and the order of series connection is changed by
controlling a connecting state of the four switches.
4. The power supply apparatus according to claim 3, wherein the
detecting unit is connected between a terminal connected to the
ground and the ground.
5. The power supply apparatus according to claim 3, wherein a
discharge unit that makes the secondary battery discharge when
detecting the states of the secondary batteries is connected
between the terminal that outputs the partial voltage and the
ground.
6. The power supply apparatus according to claim 3, wherein the two
secondary batteries are connected in parallel by the four switches
and the partial voltage is supplied to a load.
7. The power supply apparatus according to claim 1, wherein, in
detecting the states of the secondary battery by the detecting
unit, the state of one of the secondary batteries is detected by
the detecting unit and a terminal voltage of the other secondary
battery is supplied to the load as a partial voltage.
8. The power supply apparatus according to claim 1, wherein the
power supply apparatus has three secondary batteries; the power
supply apparatus outputs a composite voltage of terminal voltages
of the three secondary batteries and a terminal voltage of one of
the secondary batteries connected to a ground side as a partial
voltage; the detecting unit detects the states of the three
secondary batteries; and the changing unit changes an order of
series connection in such a manner that a secondary battery having
a relatively good state, which has been detected by the detecting
unit, is connected to a ground side.
9. The power supply apparatus according to claim 1, wherein the
power supply apparatus has four secondary batteries; the power
supply apparatus outputs a composite voltage of terminal voltages
of the four secondary batteries and outputs a terminal voltage of
one or two of the secondary batteries, which is connected to the
ground side, as a partial voltage; the detecting unit detects the
states of the four secondary batteries; and the changing unit
changes an order of the series connection in such a manner that a
secondary battery having a relatively good state, which has been
detected by the detecting unit, is connected to a ground side.
10. The power supply apparatus according to claim 1, wherein, in
the power supply apparatus, a single detecting unit that detects
the states of the secondary batteries is provided.
11. A power supplying method that has a plurality of secondary
batteries connected in series, outputs a composite voltage of all
of the secondary batteries, and outputs an output of a part of the
secondary batteries as a partial voltage, the power supply method
comprising: detecting states of the secondary batteries; and
changing an order of series connection of the plurality of
secondary batteries in such a manner that the partial voltage is
outputted from a secondary battery in a relatively good state,
based on a detection result of the detecting unit.
12. The power supplying method according to claim 11, wherein, in
the power supplying method, a changing switch is switched only when
a current detected in the detecting is less than or equal to a
predetermined current.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation application of International Patent
Application No. PCT/JP2012/065898 filed Jun. 21, 2012, which claims
the benefit of Japanese Patent Application No. 2011-145149, filed
Jun. 30, 2011, the full contents of all of which are hereby
incorporated by reference in their entirety.
BACKGROUND
[0002] 1. Technical Field
[0003] The present disclosure relates to a power supply apparatus
and a power supply method.
[0004] 2. Background Art
[0005] There are many large-sized vehicles such as trucks or buses
that have two power supplies a 24V-power supply that mainly drives
a starter motor and a 12V-power supply that drives in-vehicle
accessories. As a method of supplying power from the two power
supplies, it is common to connect 12V-secondary batteries in
series, and to obtain 24V as their total voltage and obtain 12V
from one of the secondary batteries.
[0006] As has been described above, when the two secondary
batteries are connected in series in the aforementioned manner,
there may be a case in which the discharging of a secondary battery
on a 12V-side progresses faster as compared to the other secondary
battery, and a difference in the charging rate may occur between
the two secondary batteries. In such a case, the life of one of the
secondary batteries may shorten, or as the discharging progresses,
it may not be able to drive the starter motor.
[0007] Accordingly, in order to prevent such a situation, in the
related art, there are a technique of connecting a resistance
element to a secondary battery on a high-voltage side and
discharging electricity to balance them (Japanese Laid-Open Patent
Publication No. 2007-267454), a technique of transferring an
electric power from a secondary battery of a high voltage to a
secondary battery of a low voltage using a convertor or a
transformer (Japanese Laid-Open Patent Publication Nos. 2010-93980
and 2000-60019), and a technique of equalizing a charged state by
bypassing a secondary battery that has come to a full-charge state
during the charging (Japanese Laid-Open Patent Publication No.
1998-14002).
[0008] According to the technique described in Japanese Laid-Open
Patent Publication No. 2007-267454, since an electric power is
converted into heat by a resistor, there is a disadvantage that
efficiency is low due to an occurrence of a loss of an electric
power. According to the technique described in Japanese Laid-Open
Patent Publication No. 2010-93980, since an electric power is
transferred between the secondary batteries, there is a
disadvantage that time is required for the transfer. According to
the technique described in Japanese Laid-Open Patent Publication
No. 2000-60019, since an electric power is transferred using a
transformer, there is a disadvantage that the transfer is not
appropriately performed due to a winding ratio of the coil and that
time is required for the transfer. Further, according to the
technique described in Japanese Laid-Open Patent Publication No.
1998-14002, since it is a technique of managing the charging, there
is a disadvantage that the discharging cannot be managed.
SUMMARY
[0009] Accordingly, it is an object of the present disclosure to
provide a power supply apparatus and a power supply method that can
perform charge/discharge management of a plurality of secondary
batteries efficiently in a short time.
[0010] In order to achieve the above object, a power supply
apparatus that has a plurality of secondary batteries connected in
series, outputs a composite voltage of all of the secondary
batteries, and outputs an output of a part of the secondary
batteries as a partial voltage is provided that includes a
detecting unit that detects states of the secondary batteries, and
a changing unit that changes an order of series connection of the
plurality of secondary batteries based on a detection result of the
detecting unit in such a manner that the partial voltage is
outputted from a secondary battery that is in a relatively good
state.
[0011] With such a structure, discharge/charge management of a
plurality of secondary batteries can be performed efficiently in a
short time. Further, by changing an order of series connection of
the plurality of secondary batteries in such a manner that the
partial voltage is outputted from a secondary battery that is in a
relatively good state, the load can be prevented from being
concentrated on one of the secondary batteries, and thus the life
of the battery can be lengthened.
[0012] According to another configuration, in addition to the
aforementioned configuration, the power supply apparatus has two
secondary batteries, the power supply apparatus outputs a composite
voltage of terminal voltages of the two secondary batteries and a
terminal voltage of a secondary battery connected to a ground side
as a partial voltage, the detecting unit detects states of the two
secondary batteries, and the changing unit changes an order of the
series connection in such a manner that a secondary battery that is
in a relatively good state, which has been detected by the
detecting unit, is connected to a ground side.
[0013] According to such a configuration, charge/discharge
management of two secondary batteries can be performed efficiently
in a short time.
[0014] According to another configuration, in addition to the
aforementioned configuration, the changing unit has four switches
each having a single common terminal, a first selective terminal
and a second selective terminal, a positive pole and a negative
pole of each of the two secondary batteries are connected to the
respective common terminals of the four switches, respective first
selective terminals of the four switches are connected with one
another, the respective first selective terminals being a terminal
that outputs the partial voltage, respective second selective
terminals of two switches connected to the positive pole through
the respective common terminals are connected with each other, the
respective second selective terminals being a terminal that outputs
the composite voltage, respective second selective terminals of the
two switches connected to the negative pole through the respective
common terminals are connected with each other, the respective
second selective terminals being a terminal that is connected to a
ground, and the order of series connection is changed by
controlling a connecting state of the four switches.
[0015] According to such configuration, charge/discharge management
of two secondary batteries can be performed efficiently with a
simple configuration.
[0016] According to another configuration, in addition to the
aforementioned configuration, the detecting unit is connected
between a terminal connected to the ground and the ground.
[0017] With such a configuration, by positively detecting a current
flowing to the two secondary batteries, the states of the secondary
batteries can be detected accurately.
[0018] According to another configuration, in addition to the
aforementioned configuration, a discharge unit that makes the
secondary battery discharge when detecting the states of the
secondary batteries is connected between the terminal that outputs
the partial voltage and the ground.
[0019] With such a configuration, by causing the secondary battery
to discharge and by detecting the voltage and current during the
discharge, the states of the secondary batteries can be detected
accurately.
[0020] According to another configuration, in addition to the
aforementioned configuration, the two secondary batteries are
connected in parallel by the four switches and the partial voltage
is supplied to a load.
[0021] With such a configuration, when outputting a partial
voltage, an unbalance in the states can be prevented by connecting
the secondary batteries in parallel.
[0022] According to another configuration, in addition to the
aforementioned configuration, in detecting the states of the
secondary battery by the detecting unit, the state of one of the
secondary batteries is detected by the detecting unit and a
terminal voltage of the other secondary battery is supplied to the
load as a partial voltage.
[0023] With such configuration, since the states of the secondary
batteries can be detected while an electric current is not flowing
to the load, the states of the secondary batteries can be detected
even more accurately.
[0024] According to another configuration, in addition to the
aforementioned configuration, the power supply apparatus has three
secondary batteries, the power supply apparatus outputs a composite
voltage of terminal voltages of the three secondary batteries and a
terminal voltage of one of the secondary batteries connected to a
ground side as a partial voltage, the detecting unit detects the
states of the three secondary batteries, and the changing unit
changes an order of series connection in such a manner that a
secondary battery having a relatively good state, which has been
detected by the detecting unit, is connected to a ground side.
[0025] According to such a configuration, charge/discharge
management of the three secondary batteries can be performed
efficiently in a short time.
[0026] According to another configuration, in addition to the
aforementioned configuration, the power supply apparatus has four
secondary batteries, the power supply apparatus outputs a composite
voltage of terminal voltages of the four secondary batteries and
outputs a terminal voltage of one or two of the secondary
batteries, which is connected to the ground side, as a partial
voltage, the detecting unit detects the states of the four
secondary batteries, and the changing unit changes an order of the
series connection in such a manner that a secondary battery having
a relatively good state, which has been detected by the detecting
unit, is connected to a ground side.
[0027] With such a configuration, charge/discharge management of
the four secondary batteries can be performed efficiently in a
short time.
[0028] According to another configuration, in addition to the
aforementioned configuration, in the power supply apparatus, a
single detecting unit that detects the states of the secondary
batteries is provided.
[0029] With such a configuration, the states of a plurality of
secondary batteries can be detected with a single state detecting
unit by changing an order of series connection of the plurality of
secondary batteries. Thereby, since a detecting unit need not be
arranged for each individual secondary battery, the cost of the
apparatus as a whole can be reduced.
[0030] According to another configuration, in addition to the
aforementioned configuration, a power supplying method that has a
plurality of secondary batteries connected in series, outputs a
composite voltage of all of the secondary batteries, and outputs an
output of a part of the secondary batteries as a partial voltage is
provided that includes detecting states of the secondary batteries,
and changing an order of series connection of the plurality of
secondary batteries in such a manner that the partial voltage is
outputted from a secondary battery in a relatively good state,
based on a detection result of the detecting unit.
[0031] With such a method, charge/discharge management of a
plurality of secondary batteries can be performed efficiently in a
short time. Also, by changing an order of series connection of the
plurality of secondary batteries in such a manner that the partial
voltage is outputted from a secondary battery in a relatively good
state, the load can be prevented from being concentrated on a
single secondary battery, and thus the life of the battery can be
lengthened.
[0032] Further, according to another configuration, in addition to
the aforementioned configuration, in the power supplying method, a
changing switch is switched only when a current detected in the
detecting is less than or equal to a predetermined current.
[0033] With such a method, it is possible to prevent deterioration
of contacts of a switch due to the switching during a large current
flow having a current value greater than or equal to a
predetermined current value.
[0034] According to the present disclosure, a power supply
apparatus and a power supply method that can perform a discharge
and charge management of a plurality of secondary batteries
efficiently in a short time can be provided.
[0035] Further, according to the present disclosure, by changing an
order of series connection of the plurality of secondary batteries
in such a manner that the partial voltage is outputted from a
secondary battery that is in a relatively good state, the load can
be prevented from being concentrated on one of the secondary
batteries, and thus the life of the battery can be lengthened.
[0036] Further, the states of a plurality of secondary batteries
can be detected by a single state detecting unit by changing the
order of series connection of the plurality of secondary batteries.
Thereby, since a detecting unit need not be provided for each
individual secondary battery, the cost of the entire apparatus can
be reduced.
BRIEF DESCRIPTION OF DRAWINGS
[0037] FIG. 1 is a diagram showing an exemplary configuration of a
power supply apparatus according to an embodiment of the present
disclosure.
[0038] FIG. 2 is a flow chart for explaining a process flow
executed in the embodiment shown in FIG. 1.
[0039] FIGS. 3A and 3B are diagrams showing a change in a connected
state in the embodiment shown in FIG. 1.
[0040] FIGS. 4A and 4B are diagrams showing a change in a connected
state at the time of measurement in the embodiment shown in FIG.
1.
[0041] FIG. 5 is a flow chart for explaining a process flow
executed in an embodiment shown in FIG. 1.
[0042] FIG. 6 is a diagram showing a connected state when the flow
chart shown in FIG. 5 is executed.
[0043] FIG. 7 is a diagram for explaining another embodiment of the
present disclosure.
[0044] FIG. 8 is a diagram for explaining yet another embodiment of
the present disclosure.
[0045] FIG. 9 is a diagram for explaining still another embodiment
of the present disclosure.
[0046] FIG. 10 is a diagram for explaining still another embodiment
of the present disclosure.
DETAILED DESCRIPTION
[0047] Further features of the present disclosure will become
apparent from the following detailed description of exemplary
embodiments with reference to the accompanying drawings.
[0048] (A) Description of a Configuration of the Embodiment
[0049] FIG. 1 is a diagram illustrating an exemplary configuration
of a power supply apparatus according to an embodiment of the
present disclosure. As shown in FIG. 1, a power supply apparatus 10
includes secondary batteries 11 and 12, switches 13 to 16, a state
detecting unit 17 and a control unit 18 as its main constituent
elements, and a discharging circuit 19, a 12V-load 20, a 24V-load
21, a starter motor 22 and an alternator 23 are connected
externally.
[0050] Each of the secondary batteries 11 and 12 is constituted by,
for example, a secondary battery such as a lead-acid battery, a
nickel-cadmium battery, a nickel metal hydride battery, a
lithium-ion battery, and, for example, generates and outputs a
direct current electric power of 12V.
[0051] The switches 13 to 16 are constituted by, for example,
electromagnetic relays. The switch 13 has a common terminal
connected to a positive pole of the secondary battery 11, a
selective terminal connected to a connection point A, and another
selective terminal connected to a connection point B. The switch 13
is controlled by the control unit 18 and connects the positive pole
of the secondary battery 11 either to the connection point A or to
the connection point B. The switch 14 has a common terminal
connected to a negative pole of the secondary battery 11, a
selective terminal connected to the connection point B, and another
selective terminal connected to a connection point C. The switch 14
is controlled by the control unit 18 and connects the negative pole
of the secondary battery 11 either to the connection point B or to
the connection point C.
[0052] The switch 15 has a common terminal connected to a positive
pole of the secondary battery 12, a selective terminal connected to
the connection point A, and another selective terminal connected to
the connection point B. The switch 15 is controlled by the control
unit 18 and connects the positive pole of the secondary battery 12
either to the connection point A or to the connection point B. The
switch 16 has a common terminal connected to a negative pole of the
secondary battery 12, a selective terminal connected to the
connection point B, and another selective terminal connected to the
connection point C. The switch 16 is controlled by the control unit
18 and connects the negative pole of the secondary battery 12
either to the connection point B or to the connection point C.
[0053] The state detecting unit 17 detects states of the secondary
batteries 11 and 12 and notifies the control unit 18. More
specifically, the state detecting unit 17 detects a current, a
voltage and a temperature of the secondary batteries 11 and 12, and
notifies the control unit 18.
[0054] The control unit 18 is constituted by, for example, a CPU
(Central Processing Unit), a ROM (Read Only Memory), a RAM (Random
Access Memory), or the like, and the switches 13 to 16 and the
discharging circuit 19, etc., are controlled based on the states of
the secondary batteries 11 and 12 supplied from the state detecting
unit 17. Note that in FIG. 1, each broken line connected from the
control unit 18 to each part indicates a control line.
[0055] In response to the control of the control unit 18, the
discharging circuit 19 periodically discharges electricity from the
secondary battery connected to the connection point B. By detecting
a current, a voltage, and an internal resistance at this instant, a
charging rate SOC (State of Charge) or a degradation state SOH
(State of Health) are measured.
[0056] The 12V-load 20 is, for example, a car audio equipment, a
car navigation device, a horn, etc., that is operated by a voltage
of 12V applied to the connection point B. The 24V-load 21 is, for
example, an ABS (Anti Brake System), a TCU (Transmission Control
Unit), etc., that operates with a voltage of 24V applied to the
connection point A.
[0057] The starter motor 22 is constituted by a direct-current
motor and starts up an engine, not shown, by supplying a direct
current power of 24V. The alternator 23 is rotationally driven by
an engine, not shown, and produces a direct current power of 24V
and charges the secondary batteries 11 and 12.
[0058] (B) Description of Operation According to the Embodiment
[0059] An operation of the present embodiment will now be
described. FIG. 2 is a flow chart for explaining a process flow
executed in the present embodiment. When the process shown in FIG.
2 is started, the following steps are performed.
[0060] In step S10, the control unit 18 determines whether or not
an ignition key, not shown, has been operated to bring an ignition
switch into an ignition ON state. If it is determined to be in an
ignition ON state (step S10: Yes), the process proceeds to step
S11, and if not (step S10: No), the process is terminated.
Specifically, in a case where a driver has brought an ignition
switch into an ignition ON state to start up the engine of the
vehicle, the process proceeds to step S11.
[0061] In step S11, the control unit 18 controls the switches 13 to
16 to select one of the secondary batteries 11 and 12 as an object
to be measured. FIG. 3A shows a state in which, by the switches 13
to 16, the secondary battery 12 has been selected as an object to
be measured, and FIG. 3B shows a state in which the secondary
battery 11 has been selected as an object to be measured. In the
state shown in FIG. 3A, since each of the switches 13 and 14 has
selected a selective terminal on an upper side in the diagram and
each of the switches 15 and 16 has selected a selective terminal on
a lower side in the diagram, the positive pole of the secondary
battery 12 is connected to the discharging circuit 19 and the
negative pole is grounded via the state detecting unit 17. In the
state shown FIG. 3B, since each of the switches 13 and 14 has
selected a selective terminal on a lower side in the diagram and
each of the switches 15 and 16 has selected a selective terminal on
an upper side in the diagram, the positive pole of the secondary
battery 11 is connected to the discharging circuit 19 and the
negative pole is grounded via the state detecting unit 17.
[0062] In step S12, the control unit 18 measures a charging rate
SOC1 and a state of degradation SOH1 of the secondary battery
selected in step S11. Specifically, the control unit 18 controls
the discharging circuit 19 to obtain a current value and a voltage
value from the state detecting unit 17 for a case where the
selected secondary battery is discharged with a constant current,
and retrieves an SOC corresponding to the obtained current value
and the obtained voltage value from, for example, a table, and
defines the retrieved SOC as SOC1. At this time, correction by
temperature obtained from the state detecting unit 17 and
correction by degradation based on SOH1 described below are
performed. Further, the control unit 18 also controls the
discharging circuit 19, causes the selected secondary battery to be
discharged at a predetermined frequency, obtains an internal
resistance from changes in voltage and current at that time and
obtains SOH1 from the obtained internal resistance. The frequency
of the discharge used for measurement can be, for example, chosen
appropriately in the range of several tens of Hz to several kHz.
FIG. 4A shows a state in which the secondary battery 12 is measured
and FIG. 4B shows a state in which the secondary battery 11 is
measured. In FIG. 4A, the positive pole of the secondary battery 12
is connected to the discharging circuit 19 and the negative pole is
grounded via the state detecting unit 17. In FIG. 4B, the positive
pole of the secondary battery 11 is connected to the discharging
circuit 19, and the negative pole is grounded via the state
detecting unit 17. In such a state, SOC1, SOH1, SOC2 and SOH2 of
the secondary batteries 11 and 12 are measured.
[0063] In step S13, based on information from the state detecting
unit 17, the control unit 18 determines whether or not the current
flowing from the secondary battery selected in step S11 to the
ground has a current value lower than a predetermined current
value. If it is lower than the predetermined current value, the
process proceeds to step S14 (step S13: Yes) and if not, a similar
process is repeated (step S13: No).
[0064] In step S14, the control unit 18 controls the switches 13 to
16, and selects the other one of the secondary batteries 11 and 12,
which was not selected in step S11, as an object to be measured.
For example, in a case where the secondary battery 11 has been
selected in step S11 as an object to be measured (in the case of
FIG. 3B), the secondary battery 12 is selected in step S14 as an
object to be measured (brought to FIG. 3A). The connections are
switched over after having determined whether or not it is less
than the predetermined current value in step S13. One of the
reasons for this is to prevent the apparatus from being overloaded
by a high voltage which may be generated by self-induction due to
the switching, which may be caused when the switches 13 to 16 are
switched over while a big current having a current value greater
than or equal to a predetermined current value is flowing and in a
case where a 12V-load 20 or a 24V-load 21 includes an inductive
load. Another reason is to prevent the degradation of the contacts
of the switches 13 to 16 caused by the switching while a relatively
large current is flowing. The predetermined current value can be
appropriately set by an allowable current value or the like of the
switches.
[0065] In step S15, the control unit 18 measures SOC2 and SOH2 of
the other secondary battery selected in step S14. The measuring
process is similar to that of step S12.
[0066] In step S16, SOC1 of one of the secondary batteries measured
in step S12 is compared with SOC2 of the other of the secondary
batteries measured in step S15. If SOC1>SOC2 (step S16: Yes),
the process proceeds to step S17, and if not (step S16: No), the
process proceeds to step S18. For example, in a case where
SOC1>SOC2 is satisfied, where SOC1 is the charging rate of the
secondary battery 11 and SOC2 is a charging rate of the secondary
battery 12, the process proceeds to step S17.
[0067] In step S17, the control unit 18 controls the switches 13 to
16, and sets one of the secondary batteries to a low-voltage side.
More specifically, in a case where the secondary battery 12 is
selected as one of the secondary batteries, SOC1 represents a
measured value for the secondary battery 12 and SOC2 represents a
measured value for the secondary battery 11. When SOC1>SOC2 is
satisfied, i.e., when the secondary battery 12 has a higher
charging rate than that of the secondary battery 11, the secondary
battery 12 is set to a low-voltage side, and comes to a connected
state shown in FIG. 3A. As a result, the 24V-load 21 and the
starter motor 22 are supplied with an electric power from both of
the secondary batteries 11 and 12, and the 12V-load 20 is supplied
with an electric power from the secondary battery 12 having a
higher charging rate.
[0068] In step S18, the control unit 18 controls the switches 13 to
16, and the other secondary battery is set at the low-voltage side.
More specifically, when the secondary battery 12 is selected as one
of the secondary batteries, SOC1 becomes a measured value of the
secondary battery 12 and SOC2 becomes a measured value of the
secondary battery 11. In a case where SOC1<SOC2 is satisfied,
i.e., when the secondary battery 11 has a charging rate higher than
that of the secondary battery 12, the secondary battery 11 is set
at the low-voltage side, and comes to a connected state shown in
FIG. 3B. As a result, the 24V-load 21 is supplied with an electric
power from both the secondary batteries 11 and 12, and the 12V-load
20 is supplied with an electric power from the secondary battery 11
having a higher charging rate.
[0069] In the case of SOC1=SOC2, for example, it is possible to
select one of them at random or compare SOH1 with SOH2, and to set
the secondary battery in which the degradation state has not
progressed (one with a greater SOH value) to the low-voltage
side.
[0070] In step S19, the control unit 18 determines whether or not
SOH1 of one of the secondary batteries is less than a predetermined
threshold Th. If SOH1 is less than the threshold Th (step S19:
Yes), the process proceeds to step S20, and if not (step S19: No),
the process proceeds to step S21. Specifically, if SOH1 is less
than a predetermined threshold Th as compared to SOH of a new
secondary battery, the process proceeds to step S20, and if not,
the process proceeds to step S21. The predetermined threshold can
be appropriately set depending on a property or the like of the
secondary battery to be used, and when a lead battery is used, it
can be set in the range of, for example, 30 to 60%.
[0071] In step S20, the control unit 18 presents a message for
encouraging the replacement of one of the secondary batteries.
Specifically, in step S19, when it is determined that SOH1 of one
of the secondary batteries is less than 50% of the new product, for
example, a message for encouraging the replacement of one of the
secondary batteries is presented on a display unit, not shown.
[0072] In step S21, the control unit 18 determines whether or not
SOH2 of the other secondary battery is less than the predetermined
threshold Th. If it is less than the threshold Th, the process
proceeds to step S22 (step S21: Yes), and if not (step S21: No),
the process terminates. Details of this process are similar to the
case of step S19.
[0073] In step S22, the control unit 18 presents a message for
encouraging the replacement of the other secondary battery. Details
of this process are similar to the case of step S20.
[0074] According to the aforementioned process, when a driver has
operated an ignition key to start up the engine of the vehicle and
an ignition switch is brought into an ignition ON state, the
secondary batteries 11 and 12 are sequentially selected and the
respective SOC and SOH are measured. Then, since the secondary
battery having a greater SOC is selected and connected to the
low-voltage side, the 12V-load 20 is supplied with an electric
power from the secondary battery having a greater SOC. Thereby, an
unbalance between the charging rates of the secondary batteries is
corrected. When the SOHs of the secondary batteries 11 and 12 have
become less than the predetermined threshold Th, a message for
encouraging the replacement is presented.
[0075] Referring now to FIG. 5, a case in which the secondary
batteries 11 and 12 are connected in parallel and an electric power
is supplied to the 12V-load 20 will be described. When a flow chart
shown in FIG. 5 is started, the following steps are performed.
[0076] In step S30, the control unit 18 determines whether or not
an ignition key, not shown, has been operated and an ignition
switch has come to an ignition ON state. If is determined to be in
an ignition ON state (step S30: Yes), the process proceeds to step
S32, and if not (step S30: No), the process proceeds to step
S31.
[0077] In step S31, the control unit 18 determines whether or not
an ignition key, not shown, has been operated and it has come to an
ACC (Accessory) ON state. If it is determined to be in an ON state
(step S31: Yes), the process proceeds to step S32, and if not (step
S31: No), the process terminates.
[0078] In step S32, the control unit 18 determines whether or not
the engine is stopped. If the engine is stopped (step S32: Yes),
the process proceeds to step S33, and if not (step S32: No), the
process is terminated. For example, when it is brought to an
ignition ON state or an ACC ON state while the engine is being
stopped (when power is supplied to the 12V-load 20), the process
proceeds to step S33, and if not (e.g., when the engine is started
up), the process is terminated.
[0079] In step S33, the control unit 18 controls the switches 13 to
16, and as shown in FIG. 6, the secondary batteries 11 and 12 are
brought to a state where they are connected in parallel. That is,
in the example of FIG. 6, all of the switches 13 to 16 are in a
state where they are connected to the lower selective terminals and
the positive poles of the secondary batteries 11 and 12 are both
connected to the connection point B, and, the negative poles are
both connected to the connection point C.
[0080] According to the aforementioned process, since an electric
power is supplied to the 12V-load 20 with the secondary batteries
11 and 12 being connected in parallel, in a state where the engine
is stopped and the charging is not performed, it is possible to
prevent a decrease in a charging rate of one of the secondary
batteries only.
[0081] As has been described above, in the present embodiment, an
order of series connection of the secondary batteries 11 and 12 is
changed by the switches 13 to 16 depending on the state of the
secondary batteries 11 and 12. Therefore, an unbalance between the
charging rates can be corrected by setting the secondary battery
having a high charging rate to the low-voltage side and supplying
an electric power to the 12V-load 20. In this manner, since
concentration of a load on a single secondary battery can be
avoided, the life of the battery can be lengthened.
[0082] Further, in the present embodiment, since SOC and SOH are
measured while selecting the secondary batteries 11 and 12 one at a
time using the switches 13 to 16, the measurement can be performed
accurately. In this manner, since the states of the two secondary
batteries 11 and 12 can be detected with a single state detecting
unit 17 and thus it is not necessary to provide a state detecting
unit for each of the secondary batteries, a cost reduction for the
overall apparatus can be achieved.
[0083] Further, in the present embodiment, since the connections
are changed by the switches, an unbalance between the charging
rates of the secondary batteries can be corrected while reducing a
power loss.
[0084] Further, in the present embodiment, SOH of the secondary
batteries 11 and 12 are measured and when they are less than the
predetermined threshold Th, a message for encouraging the
replacement is presented. Accordingly, it is possible to know the
time for replacement of the secondary batteries 11 and 12.
[0085] Further, in the present embodiment, in a state where the
engine is stopped and the alternator 23 is not in operation, when
it is brought to an ignition ON state or an ACC ON state, the
secondary batteries 11 and 12 are brought into parallel connection
and the 12V-load 20 is supplied with an electric power.
Accordingly, it is possible to prevent only one of the secondary
batteries from being discharged which may lead to an occurrence in
an unbalance in the charging rate.
[0086] (C) Variant Embodiments
[0087] Each of the above embodiments is described by way of example
and various variant embodiments other than the embodiments
described above exist. For example, in the aforementioned
embodiment, an example in which the secondary batteries 11 and 12
have a terminal voltage of 12V was described by way of example, but
may also be of other voltages.
[0088] In the flow chart shown in FIG. 2, the state of the
secondary batteries 11 and 12 are determined based on the charging
rates SOC1 and SOC2, but the state of the secondary batteries 11
and 12 may also be determined based on the degradation states SOH1
and SOH2. Specifically, SOH1 and SOH2 may be compared and the
secondary battery having a greater value may be connected to the
low-voltage side. Alternatively, it is possible to perform the
determination based on both of SOC1, SOC2 and SOH1, SOH2.
Specifically, it can be determined based on magnitudes of products
SOC1.times.SOH1 and SOC2.times.SOH2.
[0089] In the aforementioned embodiments, the charging rate SOC and
the degradation state SOH are detected based on the changes in
current and voltage at the time of discharge by the discharging
circuit 19. However, the charging rate SOC and the degradation
state SOH may be detected in accordance with a method other than
this.
[0090] In the aforementioned embodiment, the flow chart shown in
FIG. 2 is performed in such a manner that the process from step S11
onwards are performed in a case where the ignition key is brought
to an ignition ON state, but the process from step S11 onwards may
also be performed in a case where the engine is stopped.
Alternatively, instead of immediately after the stoppage of the
engine, the processes from step S11 onwards may be performed after
a predetermined period of time has passed since the engine has been
stopped and the secondary batteries 11 and 12 have come to a stable
state. Also, SOC of the secondary battery on the ground side may be
detected while running or idling, and in a case where the SOC has
become a predetermined threshold or less, the order of series
connection of the two secondary batteries may be changed at a
predetermined timing (e.g., after the engine has stopped or when
the discharging and charging current has come to a predetermined
threshold or below). Further, the timing of changing the order of
series connection is not limited to after the stoppage of the
engine, and the order may also be changed in a case where the
charge/discharge current has become a predetermined threshold or
below during the running or idling. Further, SOC or SOH that has
been measured during the running, during the stoppage or during the
idling may be presented to the user by being displayed on a display
unit disposed on a front panel, etc.
[0091] Further, in the aforementioned embodiment, an
electromagnetic relay is used as switch, but, for example, a
semiconductor switch such as an FET (Field Effect Transistor) or an
IGBT (Isolated Gate Bipolar Transistor) may also be used.
[0092] Further, in the aforementioned embodiment, the discharging
circuit 19 and the 12V-load 20 are connected in parallel with the
secondary battery to be measured. However, the discharging circuit
19 and the 12V-load 20 may be connected to another secondary
battery. FIG. 7 is a diagram showing an embodiment in which the
discharging circuit 19 and the 12V-load 20 are connected to another
secondary battery. In the example of FIG. 7, as compared to the
case of FIG. 1, the switches 14 and 16 are replaced with switches
34 and 36, and switches 37 and 38 are newly added. Here, the switch
34 has a single common terminal and three selective terminals. The
common terminal is connected to the negative pole of the secondary
battery 11, an upper selective terminal is connected to the
connection point B, a middle selective terminal is connected to the
connection point C, and a lower selective terminal is grounded.
Similarly, the switch 36 also has a single common terminal and
three selective terminals. The common terminal is connected to the
negative pole of the secondary battery 12, an upper selective
terminal is connected to the connection point B, a middle selective
terminal is connected to the connection point C, and a lower
selective terminal is grounded. The switch 37 has two selective
terminals and a single common terminal. The switch 37 selects one
of the selective terminals of either the switch 13 or 15 and
connects it to the 24V-load 21, the starter motor 22 and the
alternator 23. The switch 38 has two selective terminals and a
single common terminal. The selective terminals are connected to
the selective terminals of the switches 13 and 15, respectively,
and the common terminal is connected to the discharging circuit
19.
[0093] An operation of the embodiment of FIG. 7 will now be
described. In the state shown in FIG. 7, the switch 13 has selected
a lower selective terminal, the switch 15 has selected an upper
selective terminal, the switch 34 has selected a lower selective
terminal, the switch 36 has selected a middle selective terminal,
and the switches 37 and 38 have selected left selective terminals.
In this case, the positive pole of the secondary battery 12 is
connected to the discharging circuit 19 via the switches 15 and 38,
and the negative pole is grounded via the state detecting unit 17.
On the other hand, the positive pole of secondary battery 11 is
connected to the 12V-load 20 via the switch 13, and the negative
pole is grounded via the switch 34.
[0094] When the secondary battery 11 is selected as an object to be
measured, it is to be brought to a state where the switch 13 has
selected an upper selective terminal, the switch 15 has selected a
lower selective terminal, the switch 34 has selected a middle
selective terminal, the switch 36 selects a lower selective
terminal, and the switches 37 and 38 have selected right selective
terminals.
[0095] When the measurement is terminated, and, for example, when
the secondary battery 11 is set to the low-voltage side, it is to
be brought to a state where the switch 13 has selected a lower
selective terminal, the switch 15 has selected an upper selective
terminal, the switch 34 has selected a lower selective terminal,
and switch 36 has selected an upper selective terminal, and the
switches 37 and 38 have selected right selective terminals. On the
other hand, in a case where the secondary battery 12 is set to the
low-voltage side, it is to be brought to a state where the switch
13 has selected the upper selective terminal, the switch 15 has
selected the lower selective terminal, the switch 34 has selected
the upper a selective terminal, the switch 36 has selected the
lower selective terminal, and the switches 37 and 38 have selected
the left selective terminal.
[0096] When it is brought to a state where the switches 13 and 15
have selected the lower selective terminals and the switches 34 and
36 have selected the lower selective terminals, the secondary
batteries 11 and 12 may be connected in parallel and an electric
power may be supplied to 12V-load 20 as shown in FIG. 6.
[0097] As has been described above, in the embodiment shown in FIG.
7, since it is possible to connect only one of the secondary
batteries to the discharging circuit 19, an influence of the
12V-load 20 is excluded and measurement can be performed
accurately.
[0098] FIG. 8 is a diagram showing still another embodiment. In the
example of this FIG. 8, as compared to the case of FIG. 1, switches
37, 38, 40 and 41 are newly added. Other configuration is similar
to the case of FIG. 1. The switch 37 has two selective terminals
and a single common terminal, selects one of the selective
terminals of either the switch 13 or 15, and connects to the
24V-load 21, the starter motor 22 and the alternator 23 that are
connected to the common terminal. The switch 38 has two selective
terminals and a single common terminal. The selective terminals are
connected to the selective terminals of the switches 13 and 15,
respectively, and the common terminal is connected to the
discharging circuit 19. The switch 40 has two selective terminals
and a single common terminal. The selective terminals are connected
to the lower selective terminal of the switches 14 and 16,
respectively, and the common terminal is connected to the state
detecting unit 17. The switch 41 has two selective terminals and a
single common terminal. The selective terminals are connected to
the lower selective terminals of the switches 14 and 16,
respectively, and the common terminal is grounded.
[0099] In the example shown in FIG. 8, the switches 13 and 14 have
selected the lower selective terminals, the switch 15 has selected
the upper selective terminal, the switch 16 has selected the lower
selective terminal, the switches 37 and 38 have selected the left
selective terminals, and the switches 40 and 41 have selected the
lower selective terminal. In such a connected state, the secondary
battery 11 is connected to the 12V-load 20. Also, since the
positive pole of the secondary battery 12 is connected to the
discharging circuit 19 and the negative pole is connected to the
state detecting unit 17, the secondary battery 12 can be measured
independently.
[0100] On the other hand, in a state where the switch 13 has
selected the upper selective terminal, the switch 14 has selected a
lower selective terminal, the switches 15 and 16 have selected a
lower selective terminal, the switches 37 and 38 have selected the
right selective terminal, and the switches 40 and 41 have selected
the upper selective terminal, the secondary battery 12 is connected
to the 12V-load 20. Since the positive pole of the secondary
battery 11 is connected to the discharging circuit 19 and the
negative pole is connected to the state detecting unit 17, the
secondary battery 11 can be measured independently.
[0101] When the measurement is terminated and the secondary battery
11 is to be set to the low-voltage side, the switches 13 and 14 are
set to select the lower selective terminals, the switches 15 and 16
are set to select the upper selective terminals, the switches 37
and 38 are set to select the right selective terminals, and the
switches 40 and 41 are set to select the lower selective terminals.
On the other hand, when the secondary battery 12 is to be set to
the low-voltage side, the switches 13 and 14 are set to select the
upper selective terminals, the switches 15 and 16 are set to select
the lower selective terminals, the switches 37 and 38 are set to
select the left selective terminals, and the switches 40 and 41 are
set to select the upper selective terminals.
[0102] As has been described above, in the embodiment shown in FIG.
8, since it is possible to connect only one of the secondary
batteries to the discharging circuit 19, an influence of the
12V-load 20 can be excluded and measurement can be performed
accurately.
[0103] In each of the aforementioned embodiments, a case in which
two secondary batteries 11 and 12 are connected in series has been
taken as an example, but three or more secondary batteries may be
connected in series. FIG. 9 shows an embodiment for a case in which
three secondary batteries 11, 12 and 50 are connected in series. In
an example shown in this diagram, as compared to the case of FIG.
1, a secondary battery 50 and switches 51 to 55 are added, the
24V-load 21 is replaced with a 36V-load 56, and the alternator 23
is replaced with an alternator 23A.
[0104] Here, regarding the switch 51, a common terminal is
connected to a connection point A, one of the selective terminals
is connected to one of the selective terminals of other switches 52
to 54, and the other selective terminal is connected to the other
selective terminal of the switch 53. Regarding the switch 52, a
common terminal is connected to a connection point C, one of the
selective terminals is connected to one of the selective terminals
of other switches 51, 53 and 54, and the other selective terminal
is connected to the other selective terminal of the switch 54.
Regarding the switch 53, a common terminal is connected to a
positive pole of secondary battery 50, one of the selective
terminals is connected to one of the selective terminals of the
other switches 51, 52 and 54, and the other selective terminal is
connected to the other selective terminal of the switch 51.
Regarding the switch 54, a common terminal is connected to a
negative pole of the secondary battery 50, one of the selective
terminals is connected to one of the selective terminals of the
other switches 51, 52, and 53, and the other selective terminal is
connected to the other selective terminals of the switch 52.
Regarding the switch 55, a common terminal is connected to the
12V-load 20, one of the selective terminals is connected to a
connection point E, and the other of the selective terminals is
connected to the connection point B.
[0105] The 36V-load 56 is a load whereto a voltage of 36V is
supplied. The alternator 23A outputs a voltage of 36V, and charges
the secondary batteries 11, 12 and 50.
[0106] An operation of an embodiment shown in FIG. 9 will now be
described. In the embodiment shown in FIG. 9, the operation of the
switches 13 to 16 is similar to the case of FIG. 1, and an order of
series connection of the secondary batteries 11 and 12 is changed
by a connecting state of these switches 13 to 16. On the other
hand, the switches 51 to 54 change an order of the series
connection of the secondary batteries 11 and 12 and the secondary
battery 50. Specifically, as shown in FIG. 9, when the switches 51
and 52 have selected upper selective terminals, the switches 53 and
54 have selected lower selective terminals, and the switch 55 has
selected an upper selective terminal, the secondary battery 50 is
grounded via the state detecting unit 17 and the secondary
batteries 11 and 12 are connected in series in this order to a
positive side of the secondary battery 50. At this time, the
12V-load 20 is supplied with an electric power from the secondary
battery 50 and the 36V-load 56 is supplied with an electric power
from the secondary batteries 11, 12 and 50. In such a state,
similarly to the case of FIG. 1, the order of connection of the
secondary batteries 11 and 12 can be changed by changing a
connecting state of the switches 13 to 16.
[0107] On the other hand, when the switches 51 and 52 have selected
lower selective terminals, the switches 53 and 54 have selected
upper selective terminals, and the switch 55 has selected a lower
selective terminal, the secondary battery 12 is grounded and the
secondary batteries 11 and 50 are, in this order, connected to the
positive side of the secondary battery 12. At this time, the
12V-load 20 is supplied with an electric power from the secondary
battery 12 and the 36V-load 56 is supplied with an electric power
from the secondary batteries 11, 12 and 50. In such a state,
similarly to the case of FIG. 1, the order of connection of the
secondary batteries 11 and 12 can be changed by changing the
connecting state of the switches 13 to 16.
[0108] As has been described above, in the embodiment shown in FIG.
9, since the three secondary batteries 11, 12 and 50 can be
connected in series and the order of series connection can be
changed, the charge/discharge control of three secondary batteries
can be performed easily.
[0109] Referring now to FIG. 10, a case in which four secondary
batteries 11, 12, 61 and 62 are connected in series will be
described. In the embodiment shown in FIG. 10, as compared to FIG.
1, secondary batteries 61 and 62, switches 63 to 71, and a 48V-load
72 are added, and the alternator 23 is replaced with an alternator
23B.
[0110] The secondary batteries 61 and 62 and the switches 63 to 66
are connected similarly to a manner in which the secondary
batteries 11 and 12 and the switches 13 to 16 are connected.
Regarding the switches 67 and 69, common terminals are connected to
the connection points A and A', respectively. One of the selective
terminals of the switches is connected with one of the selective
terminals of the other switch and also connected to one of the
selective terminals of the switches 68 and 70. The other selective
terminal thereof is connected with the other selective terminal of
the other switch and is also connected to the 48V-load 72 and the
alternator 23B. Regarding the switches 68 and 70, common terminals
are connected to the connection point C and C', respectively. One
of the selective terminals thereof is connected with the one of the
selective terminals of the other switch and also connected to one
of the selective terminals of the switches 67 and 69. The other
selective terminal thereof is connected with the other selective
terminal of the other switch and also connected to the state
detecting unit 17. Regarding the switch 71, a common terminal is
connected to the 12V-load 20. One of the selective terminals is
connected to the connection point B', and the other selective
terminal is connected to the connection point B.
[0111] An operation of the embodiment of FIG. 10 will now be
described. In the embodiment of FIG. 10, by changing the connection
of switches 67 to 70, it is possible to select which of the
secondary batteries 11 and 12 or the secondary batteries 61 and 62
are to be on the ground side. Specifically, as shown in FIG. 10,
when the switches 67 and 68 have selected the upper selective
terminals, the switches 69 and 70 have selected lower selective
terminals, and the switch 71 has selected an upper selective
terminal, the secondary batteries 61 and 62 are connected to the
ground side. At this time, the 12V-load 20 is supplied with an
electric power from the secondary battery 61, the 24V-load 21 is
supplied with an electric power from the secondary batteries 61 and
62 connected in series, and the 48V-load 72 is supplied with an
electric power from the secondary batteries 61, 62, 11 and 12
connected in series. On the other hand, when the switches 67 and 68
have selected the lower selective terminals, the switches 69 and 70
have selected the upper selective terminals, and the switch 71 has
selected a lower selective terminal, the secondary batteries 11 and
12 are connected to the ground side. At this time, the 12V-load 20
is supplied with an electric power from the secondary battery 12,
the 24V-load 21 is supplied with an electric power from the
secondary batteries 11 and 12 connected in series, and the 48V-load
72 is supplied with an electric power from the secondary batteries
61, 62, 11 and 12 connected in series.
[0112] As has been described above, in the embodiment shown in FIG.
10, since the four secondary batteries 11, 12, 61 and 62 can be
connected in series and the order of series connection can be
changed, the charge/discharge management of the four secondary
batteries can be performed in a facilitated manner.
* * * * *