U.S. patent number RE37,678 [Application Number 09/708,562] was granted by the patent office on 2002-04-30 for secondary battery power storage system.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Tatsuo Horiba, Kyoko Ikawa.
United States Patent |
RE37,678 |
Ikawa , et al. |
April 30, 2002 |
**Please see images for:
( Certificate of Correction ) ** |
Secondary battery power storage system
Abstract
The present invention provides a distributed secondary battery
type power storage system capable of maintaining the soundness of
the secondary battery and of efficient electric power charging and
discharging operations. The secondary battery power storage system
comprises a secondary battery connected to a load, a
charge/discharge unit connectable to a power system and connected
to the secondary battery, and a plurality of loads connected to the
charge/discharge unit. A power receiving object is selected and a
capacity is determined on the basis of information about the
operating condition of the plurality of loads, and the surplus
electric power remaining in the secondary battery feeding electric
power from the secondary battery to the load is fed to the selected
power receiving object through the charge/discharge unit. The
secondary battery power storage system is capable of maintaining
the soundness of the secondary battery and of efficient charging
and discharging operation.
Inventors: |
Ikawa; Kyoko (Hitachi,
JP), Horiba; Tatsuo (Hitachi, JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
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Family
ID: |
18238717 |
Appl.
No.: |
09/708,562 |
Filed: |
November 9, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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363372 |
Dec 23, 1994 |
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Reissue of: |
606226 |
Feb 23, 1996 |
05834922 |
Nov 10, 1998 |
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Foreign Application Priority Data
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Dec 27, 1993 [JP] |
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5-331000 |
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Current U.S.
Class: |
320/136 |
Current CPC
Class: |
H02J
3/32 (20130101); H02J 7/00047 (20200101); H02J
7/34 (20130101); H02J 7/00036 (20200101); H02J
7/0063 (20130101); B60L 58/21 (20190201); H02J
13/00016 (20200101); H02J 13/0003 (20130101); H02J
7/0022 (20130101); H02J 13/00034 (20200101); Y02B
90/20 (20130101); Y02T 10/70 (20130101); Y02E
60/00 (20130101); Y02T 90/168 (20130101); Y04S
40/124 (20130101); Y04S 10/126 (20130101) |
Current International
Class: |
H02J
3/32 (20060101); H02J 3/28 (20060101); H02J
7/00 (20060101); H02J 13/00 (20060101); H02J
7/34 (20060101); H01M 010/44 (); H01M 010/46 () |
Field of
Search: |
;320/121,116,125,132,134,136,149,160 ;429/61 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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39 39 522 |
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Nov 1989 |
|
DE |
|
39 39 522 |
|
Jun 1991 |
|
DE |
|
0 225 106 |
|
Nov 1986 |
|
EP |
|
0 248 461 |
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Dec 1987 |
|
EP |
|
0 334 474 |
|
Feb 1989 |
|
EP |
|
2 262 401 |
|
Jun 1993 |
|
GB |
|
12828/89 |
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Jan 1964 |
|
JP |
|
57-13933 |
|
Jan 1982 |
|
JP |
|
1-12828 |
|
Jan 1989 |
|
JP |
|
01 012828 |
|
Jan 1989 |
|
JP |
|
1-59516 |
|
Mar 1989 |
|
JP |
|
1-96833 |
|
Apr 1989 |
|
JP |
|
02 273037 |
|
Jul 1990 |
|
JP |
|
2-273037 |
|
Jul 1990 |
|
JP |
|
2-273037 |
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Nov 1990 |
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JP |
|
3-108679 |
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May 1991 |
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JP |
|
4-58493 |
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Feb 1992 |
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JP |
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WO A 90 03682 |
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Apr 1990 |
|
WO |
|
WO A90 03682 |
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Apr 1990 |
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WO |
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WO 90/03682 |
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Apr 1990 |
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WO |
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Other References
Steffens, Technische Rundschau, "Minikraftwerke in Kundennahe",
Sep. 20, 1989, vol. 81, No. 42 pp. 86-89.* .
Communication Pursuant to Article 96(2) and Rule 51(2) EPC, (Jun.
2, 1998)..
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Primary Examiner: Tso; Edward H.
Attorney, Agent or Firm: Antonelli, Terry, Stout &
Kraus, LLP
Parent Case Text
This is a continuation of application Ser. No. 08/363,372 filed on
Dec. 23, 1994 abn.
Claims
What is claimed is:
1. A secondary battery storage system for connection to a power
system, the storage system comprising:
a secondary battery connected to a secondary battery load;
a detecting device for detecting a residual electric power of said
secondary battery;
a connection unit connected to the power system and to said
secondary battery;
a control unit connected to said connection unit; and
a signal line for transmitting information about said secondary
battery through said detecting device to said control unit, wherein
said control unit controls said connection unit on the basis of
said information, wherein said information comprises measured
values for determining a residual electric power stored in the
secondary battery, wherein for discharging the residual electric
power said connection unit selects either the secondary battery
load or the power system depending on the residual electric power
stored in the secondary battery.
2. A secondary battery storage system according to claim 1, further
comprising a plurality of loads, wherein the plurality of loads is
connected to said connection unit, and said plurality of loads is
connected to said signal line, wherein for discharging the residual
electric power said connection unit selects at least a load of said
plurality of loads depending on the residual electric power stored
in the secondary battery, and wherein said information further
comprises information about the operating condition of at least one
load of said plurality of loads connected to the connection
unit.
3. A secondary battery storage system according to claim 1, further
comprising a plurality of loads, wherein the plurality of loads is
connected to said connection unit, and said plurality of loads is
connected to said signal line, wherein for discharging the residual
electric power said connection unit selects at least a load of said
plurality of loads depending on the residual electric power stored
in the secondary battery, and further comprising a plurality of
electric power storage units, wherein the plurality of electric
power storage units is connected to said connection unit, and the
plurality of electric power storage units is connected to said
signal line, wherein for discharging the residual electric power
said connection unit selects at least a unit of said plurality of
electric power storage units depending on the residual electric
power stored in the secondary battery, wherein said information
further comprises information about the operating condition of at
least one load of said plurality of loads and the operating
condition of at least one electric power storage unit of said
plurality of electric power storage units.
4. A secondary battery storage system according to claim 1, further
comprising a plurality of electric power storage units, wherein the
plurality of electric power storage units is connected to said
connection unit, and said plurality of electric power storage units
is connected to said signal line, wherein for discharging the
residual electric power said connection unit selects at least a
unit of said plurality of electric power storage units, depending
on the residual electric power stored in the secondary battery,
wherein said information further comprises information about the
operating condition of at least one unit of said plurality of
electric power storage units.
5. A secondary battery storage system according to claim 3, wherein
said secondary battery and said secondary battery load connected to
the secondary battery are separable.
6. A secondary battery storage system according to claim 1, wherein
said control unit comprises a computer and wherein the computer
measures the amount of electric power charged into the secondary
battery and the amount of electric power discharged from the
secondary battery, and calculates the amount of residual electric
power stored in the secondary battery.
7. A secondary battery storage system according to claim 1, wherein
said control unit comprises a computer and wherein the computer
measures the amount of electric power charged into the secondary
battery and the amount of electric power discharged from the
secondary battery, and calculates the amount of residual electric
power stored in the secondary battery, and an indicating unit
indicates the amount of residual electric power calculated by the
computer.
8. A secondary battery storage system according to claim 1, wherein
the secondary battery comprises a battery selected from the group
consisting of a lead-acid battery, a lithium battery, a
nickel-cadmium battery and a nickel-metal hydride battery.
9. A secondary battery storage system according to claim 3, wherein
the charge/discharge unit comprises: a dc-ac conversion means, and
a switching means for selectively connecting the power system to
the secondary battery, the plurality of loads or the plurality of
electric power storage units.
10. A secondary battery storage system according to claim 3,
wherein the plurality of electric power storage units comprises at
least a battery selected from the group consisting of lead
secondary batteries, lithium secondary batteries, nickel cadmium
secondary batteries, nickel-metal hydride secondary batteries, heat
storage and heat exchanger type electric power storage systems and
superconducting type electric power storage systems.
11. A secondary battery storage system for connection to a power
system, the storage system comprising:
a secondary battery connected to a secondary battery load;
a connection unit connected to the secondary battery, said
connection unit connected to the power system and either a
plurality of loads or a plurality of electric power storage
units;
a detecting device for detecting a residual electric power in the
secondary battery; and
a control unit for controlling the connection unit on the basis of
information from the secondary battery and at least one of the
loads of the plurality of loads or at least one of the units of the
plurality of electric power storage units, wherein for discharging
the residual electric power said connection unit selects at least a
load of said plurality of loads or a unit of said plurality of
electric power storage units depending on the residual electric
power stored in the secondary battery, wherein a controller
receives information from at least either the secondary battery or
the plurality of loads and controls the connection unit; a computer
that measures the amount of electric power charged into and the
amount of electric power discharged from the secondary battery,
calculates the amount of residual electric power stored in the
secondary battery, and comprises a memory for storing measured data
of the secondary battery and arithmetic program information, and a
controller for processing the information stored in the memory or
information given thereto from external devices, and an
analog-to-digital converter through which information provided by
the external devices is given to the controller.
12. A secondary battery storage system according to claim 11,
wherein the secondary battery, the computer and the
analog-to-digital converter are integrated.
13. A secondary battery storage system according to claim 11,
further comprising: measuring means for measuring data on discharge
history including discharge current data, discharge voltage data
and discharge temperature data and on charge history including
charge current data, charge voltage data and charge temperature
data; and a computer that receives information from the measuring
means.
14. A secondary battery storage system according to claim 11,
wherein the memory stores information on a charging method
specifying at least one of the intrinsic characteristics of the
secondary battery including charging efficiency, discharging
efficiency and temperature characteristic, and optimum charge
conditions including a maximum charge capacity, a charge current, a
charge time, a charge voltage and an upper limit voltage, and
information on discharging method specifying at least one optimum
discharge condition including a maximum discharge capacity, a
discharge current, a discharge time, a discharge voltage and a
lower limit voltage.
15. A secondary battery storage system according to claim 11,
wherein the memory stores an arithmetic program for determining
discharge capacity by integrating discharge current data given to
the analog-to-digital converter, wherein the arithmetic program
determines charge capacity by integrating charge current data, and
determines a converted charge capacity by converting charge
capacity in a real-time mode into available capacity at a
discharging rate and a temperature condition when the discharge
current data is received on the basis of a discharging efficiency
and a temperature characteristic stored in the memory, and wherein
a program calculates and indicates a residual capacity in a
real-time mode by subtracting the discharge capacity determined in
a real-time mode from the converted charge capacity determined in a
real-time mode.
16. A secondary battery storage system for connection to a power
system, the storage system comprising a connection unit connected
to the power system, and connected to at least either a plurality
of loads or a plurality of electric power storage units and having
connecting means to connect the connection unit to a secondary
battery; wherein the connection unit is controlled by a controller
on the basis of information received from the plurality of loads or
the plurality of electric power storage units, and wherein for
discharging a residual electric power of said secondary battery
said connection unit selects at least a load of said plurality of
loads or a unit of said plurality of electric power storage units
depending on the residual electric power stored in the secondary
battery, further comprising an information transmitting means for
interconnecting the controller and at least either the connecting
means or the plurality of loads connected to the connection
unit.
17. A method of operating a secondary battery storage system for
connection to a power system, the storage system comprising:
a secondary battery connected to a secondary battery load;
a detecting device for detecting a residual electric power of said
secondary battery;
a connection unit connected to the power system and to said
secondary battery;
a control unit connected to said connection unit; and
a signal line for transmitting information about said secondary
battery through said detecting device to said control unit;
the method comprising:
selecting the power system for discharging a residual electric
power of the secondary battery through the connection unit after an
electric power stored in the secondary battery is discharged to the
secondary battery load, depending on the residual electric power
stored in the secondary battery.
18. A method of operating a secondary battery storage system for
connection to a power system, the storage system comprising: a
secondary battery connected to a secondary battery load, and a
connection unit connected to the power system and connected to at
least either a plurality of loads or a plurality of electric power
storage units; the method comprising:
feeding surplus electric power from the secondary battery to at
least either a load of the plurality of loads or a unit of the
plurality of electric power storage units, depending on the
residual electric power of the secondary battery, prior to charging
said secondary battery with power from the power system.
19. A method of operating a secondary battery storage system
according to claim 18, further comprising selecting a power
receiving object and determining a feed power capacity on the basis
of information about at least one of the surplus electric power
stored in the secondary battery, the operating condition of the
plurality of loads, or the electric power storage condition of the
plurality of electric power storage units; and feeding the surplus
electric power to the selected power receiving object.
20. A method of operating a secondary battery storage system
according to claim 19, wherein the power receiving object is
selected and the power feed capacity is determined on the basis of
the information about the surplus electric power stored in the
secondary battery, the operating condition of the plurality of
loads, and the electric power storage condition of the plurality of
electric power storage units, after charging the secondary battery
through the charge/discharge unit.
21. A method of operating a secondary battery storage system
according to claim 18, further comprising determining the operating
condition of the plurality of electric power storage units after
charging the secondary battery, and selecting a power receiving
object on the basis of surplus electric power remaining after
feeding residual electric power to the secondary battery load from
the secondary battery; and feeding electric power through the
charge/discharge unit to at least one unit of the plurality of
electric power storage units.
22. A method of operating a secondary battery storage system
according to claim 18, further comprising charging the secondary
battery through the charge/discharge unit; selecting a power
receiving object and determining power feed capacity on the basis
of surplus electric power stored in the secondary battery after
feeding electric power to the secondary battery load, determining
the power storage condition of the plurality of electric power
storage units or the operating condition of the plurality of loads;
and feeding electric power from the secondary battery through the
charge/discharge unit to the selected power receiving object.
23. A method of operating a secondary battery storage system
according to claim 18, wherein the secondary battery storage system
is provided with a memory connected with the secondary battery,
wherein the method further comprises storing at least optimum
discharge conditions for the secondary battery beforehand in the
memory, and feeding the surplus electric power of the secondary
battery through the charge/discharge unit in a mode conforming to
the optimum discharge conditions.
24. A method of operating a secondary battery storage system
according to claim 18, further comprising determining the available
discharge capacity or the possible discharge time of the secondary
battery for the next discharge cycle, estimated on the basis of the
past discharge capacity or the past discharge time and change of
the discharge capacity, and discharging surplus electric power
through the charge/discharge unit according to the estimated
available discharge capacity or the estimated possible discharge
time.
25. A method of operating a secondary battery storage system
according to claim 18, wherein the secondary battery storage system
is provided with a memory connected to the secondary battery, and
wherein the method further comprises storing at least information
about optimum charge conditions for the secondary battery
beforehand in the memory, and charging the secondary battery
through the charge/discharge unit in a mode conforming to the
stored optimum charge conditions after discharging the surplus
electric power from the secondary battery.
26. A method of operating a secondary battery storage system
according to claim 18, further comprising estimating an available
discharge capacity of the secondary battery for the next discharge
cycle, after discharging the surplus electric power on the basis of
the past charge capacity or charge time and change in the charge
capacity, and charging the secondary battery through the
charge/discharge unit in a mode conforming to the estimated charge
condition.
27. A method of operating a secondary battery storage system
according to claim 18, further comprising storing the charge
capacity of the secondary battery in a memory, and estimating the
future available discharge capacity and the cycle life of the
secondary battery on the basis of the change of the charge capacity
in the past charge and discharge cycles.
28. A method of operating a secondary battery storage system
according to claim 18, wherein the secondary battery is at least
either a nickel-cadmium battery or a nickel-metal hydride battery,
and the method further comprises discharging an amount of electric
power in the range of 95% to 100% of a discharge capacity which can
be discharged in a mode conforming to the optimum discharge
conditions among the available discharge capacity for the next
discharge cycle of the secondary battery as surplus electric power,
when the residual capacity is in the range of 0% to 85% of the
charge capacity.
29. A method of operating a secondary battery storage system
according to claim 18, wherein the secondary battery is a lithium
battery, and the method further comprises discharging an amount of
electric power in the range of 80% to 95% of a discharge capacity
which can be discharged in a mode conforming to the optimum
discharge conditions among the available discharge capacity for the
next discharge cycle of the secondary battery as surplus electric
power, when the residual capacity is in the range of 5% to 80% of
the charge capacity.
30. A method of operating a secondary battery storage system
according to claim 18, further comprising feeding residual electric
power from the secondary battery to the secondary battery load,
wherein said feeding surplus electric power further comprises
discharging surplus electric power through the connection unit from
the secondary battery after said feeding residual electric power
from the secondary battery to the secondary battery load, stopping
said discharging of the surplus electric power while the secondary
battery still comprises residual electric power, and charging the
secondary battery to a charge capacity of a preceding charge
cycle.
31. A secondary battery storage system for connection to a power
system, the storage system comprising:
a secondary battery connected to a secondary battery load;
a detecting device for detecting a residual electric power of said
secondary battery;
a connection unit connected to the power system and to said
secondary battery; and
a signal line for transmitting information about said secondary
battery through said detecting device to said connection unit,
wherein said connection unit controls charging and discharging of
the secondary battery on the basis of said information, and wherein
said information comprises measured values for determining residual
electric power stored in the secondary battery, wherein for
discharging the residual electric power said connection unit
selects either the secondary battery load or the power system
depending on the residual electric power stored in the secondary
battery. .Iadd.
32. A method of operating a secondary battery system, the system
comprising:
a secondary battery that can charge and discharge;
a charge/discharge unit connected to a power system and to the
secondary battery;
a control unit connected to the charge/discharge unit; and
a signal line connected with the charge/discharge unit and at least
one of a load and an electric power storage unit;
the method comprising:
inputting at least one of an information of surplus electric power
of the secondary battery, an information of the load, and an
information of the electric power storage unit into the control
unit; and
controlling by the charge/discharge unit a discharging of the
secondary battery. .Iaddend..Iadd.
33. A method of operating a secondary battery system according to
claim 32, wherein the secondary battery charges electric power
during night period rate hours at night and discharges electric
power during day period rate hours at daytime. .Iaddend..Iadd.
34. A method of operating a secondary battery system according to
claim 32, wherein the secondary battery charges through the
charge/discharge unit and/or discharges through the
charge/discharge unit. .Iaddend..Iadd.
35. A method of operating a secondary battery system according to
claim 32, wherein information is stored in a memory which is part
of the secondary battery or which is connected to the secondary
battery of discharging of the secondary battery and/or charging of
the secondary battery. .Iaddend..Iadd.
36. A method of operating a secondary battery system according to
claim 35, wherein information is further stored in the memory of at
least one of a charging capacity of the secondary battery, a
possible discharging capacity of the secondary battery and/or a
life of the secondary battery predicted by the change of the
charging capacity. .Iaddend..Iadd.
37. A method of operating a secondary battery system for
illumination, the system comprising:
a secondary battery that can charge and discharge;
a charge/discharge unit connected to a power system and to the
secondary battery; and
a signal line connected with the charge/discharge unit and a load
for illumination;
the method comprising:
controlling discharging of the secondary battery in accordance with
information of the load for illumination. .Iaddend..Iadd.
38. A method of operating a secondary battery system for
illumination according to claim 37, wherein the charge/discharge
unit or a control unit has a timer which controls charging and/or
discharging time of the secondary battery. .Iaddend..Iadd.
39. A method of operating a secondary battery system of an electric
vehicle, the system comprising:
a secondary battery that can charge and discharge;
a charge/discharge unit connected to a power system and to the
secondary battery; and
a signal line connected with the charge/discharge unit and a load
of the electric vehicle;
the method comprising:
controlling discharging of the secondary battery by information of
the load of the electric vehicle. .Iaddend..Iadd.
40. A secondary battery system, comprising:
a secondary battery that can charge and discharge;
a charge/discharge unit connected to a power system and to the
secondary battery;
a control unit connected to the charge/discharge unit;
a signal line connected with the charge/discharge unit and at least
one of a load and an electric power storage unit; and
an inputter which inputs at least one of an information of surplus
electric power of the secondary battery, an information of the
load, and an information of the electric power storage unit into
the control unit;
wherein a discharging of the secondary battery is controlled by the
charge/discharge unit. .Iaddend..Iadd.
41. A secondary battery system according to claim 40, wherein the
secondary battery charges electric power during night period rate
hours at night and discharges electric power during day period rate
hours at daytime. .Iaddend..Iadd.
42. A secondary battery system according to claim 40, wherein the
secondary battery charges through the charge/discharge unit and/or
discharges through the charge/discharge unit. .Iaddend..Iadd.
43. A secondary battery system according to claim 40, wherein a
memory which is part of the secondary battery or which is connected
to the secondary battery stores information of discharging of the
secondary battery and/or charging of the secondary battery.
.Iaddend..Iadd.
44. A secondary battery system according to claim 43, wherein
information is further stored in the memory of at least one of a
charging capacity of the secondary battery, a possible discharging
capacity of the secondary battery and/or a life of the secondary
battery predicted by the change of the charging capacity.
.Iaddend..Iadd.
45. A secondary battery system for illumination, the system
comprising:
a secondary battery that can charge and discharge;
a charge/discharge unit connected to a power system and to the
secondary battery; and
a signal line connected with the charge/discharge unit and a load
for illumination;
wherein discharging of the secondary battery is controlled in
accordance with information of the load for illumination.
.Iaddend..Iadd.
46. A secondary battery system for illumination according to claim
45, wherein the charge/discharge unit or a control unit has a timer
which controls charging and/or discharging time of the secondary
battery. .Iaddend..Iadd.
47. A secondary battery system of an electric vehicle, the system
comprising:
a secondary battery that can charge and discharge;
a charge/discharge unit connected to a power system and to the
secondary battery; and
a signal line connected with the charge/discharge unit and a load
of the electric vehicle;
wherein discharging of the secondary battery is controlled by
information of the load of the electric vehicle.
.Iaddend..Iadd.
48. A secondary battery power storage system for supplying residual
electric power stored in a secondary battery to an external power
supply system comprising:
a secondary battery connected to a secondary battery load;
a connection unit connected to the secondary battery and to the
power supply system and to either a plurality of loads or a
plurality of electric power storage units;
a detecting device for detecting residual electric power stored in
the secondary battery; and
a control unit for controlling the connection unit on the basis of
information regarding the detected residual electric power from the
secondary battery and of information regarding operating condition
of at least one of the loads of the plurality of loads and of
information regarding operating condition of at least one of the
units of the plurality of the electric power storage units.
.Iaddend..Iadd.
49. A secondary battery power system according to claim 48, wherein
for discharging the residual electric power, said connection unit
selects at least a load of said plurality of loads or a unit of
said plurality of electric power storage units depending on the
residual electric power stored in the secondary battery, wherein a
controller receives information from at least either the secondary
or the plurality of loads and controls the connection unit.
.Iaddend..Iadd.
50. A secondary battery power system according to claim 49, further
comprising a computer that measures the amount of electric power
charged into and the amount of electric power discharged from the
secondary battery, calculates the amount of residual electric power
stored in the secondary battery, and comprises a memory for storing
measured data of the secondary battery and arithmetic program
information, and a controller for processing the information stored
in the memory of information given thereto from external devices,
and an analog-to-digital converter through which information
provided by the external devices is given to the controller.
.Iaddend..Iadd.
51. A secondary battery power system according to claim 50, wherein
the secondary battery, the computer and the analog-to-digital
converter are integrated. .Iaddend..Iadd.
52. A secondary battery power system according to claim 50, further
comprising measuring means for measuring data on discharge battery
including discharge current data, discharge voltage data and
discharge temperature data and on charge history including charge
current data, charge voltage data and charge temperature data; and
a computer that receives information from the measuring means.
.Iaddend..Iadd.
53. A secondary battery power system according to claim 50, wherein
the memory stores information on a charging method specifying at
least one of the intrinsic characteristics of the secondary battery
including charging efficiency, discharging efficiency and
temperature characteristic, and optimum charge conditions including
a maximum charge capacity, a charge current, a charge time, a
charge voltage and an upper limit voltage, and information on
discharging method specifying at least one optimum discharge
condition including a maximum discharge capacity, a discharge
current, a discharge time, a discharge voltage and a lower limit
voltage. .Iaddend..Iadd.
54. A secondary battery power system according to claim 50, wherein
the memory stores an arithmetic program for determining discharge
capacity by integrating discharge current data given to the
analog-to-digital converter, wherein the arithmetic program
determines charge capacity by integrating charge current data, and
determines a converted charge capacity by converting charge
capacity in a real-time mode into available capacity at a
discharging rate and a temperature condition when the discharge
current data is received on the basis of a discharging efficiency
and a temperature characteristic stored in the memory, and a
program calculates and indicates a residual capacity in a real-time
mode by subtracting the discharge capacity determined in a
real-time mode from the converted charge capacity determined in a
real-time mode. .Iaddend..Iadd.
55. A secondary battery power system according to claim 48, wherein
for discharging a residual electric power of said secondary battery
said connection unit selects at least a load of said plurality of
loads or a unit of said plurality of electric power storage units
depending on the residual electric power stored in the secondary
battery, further comprising an information transmitter for
interconnecting the controller and at least either the connection
means or the plurality of loads connected to the connection unit.
.Iaddend..Iadd.
56. An electric power supplying system comprising:
at least one of a power supply system for generating or
transmitting electric power;
a plurality of secondary battery power storage systems for
supplying residual electric power stored in a secondary battery to
an external power supply system comprising:
a secondary battery connected to a secondary battery load;
a connection unit connected to the secondary battery and to the
power supply system and to either a plurality of loads or a
plurality of electric power storage units;
a detecting device for detecting residual electric power stored in
the secondary battery; and
a control unit for controlling the connection unit on the basis of
information regarding the detected residual electric power from the
secondary battery and of information regarding operating condition
of at least one of the loads of the plurality of loads and of
information regarding operating condition of at least one of the
units of the plurality of the electric power storage units.
.Iaddend..Iadd.
57. An electric power supplying system according to claim 56,
wherein for discharging the residual electric power, said
connection unit selects at least a load of said plurality of loads
or a unit of said plurality of electric power storage units
depending on the residual electric power stored in the secondary
battery, wherein a controller receives information from at least
either the secondary or the plurality of loads and controls the
connection unit. .Iaddend..Iadd.
58. An electric power supplying system according to claim 57,
further comprising a computer that measures the amount of electric
power charged into and the amount of electric power discharged from
the secondary battery, calculates the amount of residual electric
power stored in the secondary battery, and comprises a memory for
storing measured data of the secondary battery and arithmetic
program information, and a controller for processing the
information stored in the memory or information given thereto from
external devices, and an analog-to-digital converter through which
information provided by the external devices is given to the
controller. .Iaddend..Iadd.
59. An electric power supplying system according to claim 58,
wherein the secondary battery, the computer and the
analog-to-digital converter are integrated. .Iaddend..Iadd.
60. An electric power supplying system according to claim 58,
further comprising measuring means for measuring data on discharge
history including discharge current data, discharge voltage data
and discharge temperature data and on charge history including
charge current data, charge voltage data and charge temperature
data; and a computer that receives information from the measuring
means. .Iaddend..Iadd.
61. An electric power supplying system according to claim 58,
wherein the memory stores information on a charging method
specifying at least one of the intrinsic characteristics of the
secondary battery including charging efficiency, discharging
efficiency and temperature characteristic, and optimum charge
conditions including a maximum charge capacity, a charge current, a
charge time, a charge voltage and an upper limit voltage, and
information on discharging method specifying at least one optimum
discharge condition including a maximum discharge capacity, a
discharge current, a discharge time, a discharge voltage and a
lower limit voltage. .Iaddend..Iadd.
62. An electric power supplying system according to claim 58,
wherein the memory stores an arithmetic program for determining
discharge capacity by integrating discharge current data given to
the analog-to-digital converter, wherein the arithmetic program
determines charge capacity by integrating charge current data, and
determines a converted charge capacity by converting charge
capacity in a real-time mode into available capacity at a
discharging rate and a temperature condition when the discharge
current data is received on the basis of a discharging efficiency
and a temperature characteristic stored in the memory, and a
program calculates and indicates a residual capacity in a real-time
mode by subtracting the discharge capacity determined in a
real-time mode from the converted charge capacity determined in a
real-time mode. .Iaddend..Iadd.
63. An electric power supplying system according to claim 56,
wherein for discharging a residual electric power of said secondary
battery said connection unit selects at least a load of said
plurality of loads or a unit of said plurality of electric power
storage units depending on the residual electric power stored in
the secondary battery, further comprising an information
transmitting means for interconnecting the controller and at least
either the connection means or the plurality of loads connected to
the connection unit. .Iaddend.
Description
BACKGROUND OF INVENTION
1. Field of Invention:
The present invention relates to a secondary battery electric power
storage system and, more particularly, to a battery system which is
provided with evaluation means of the soundness and the residual
power of a battery, the distribution of the surplus electric power
of a battery, and the optimum charge/discharge control of a
battery. Most secondary batteries for automobiles, uninterrupted
power supplies and the like have been lead-acid batteries.
The diffusion of electric power storage systems and electric
vehicles, and the development of secondary batteries capable of
storing electric power in a high energy density have been strongly
desired to meet rising necessity for the leveling of power demand
and progressively increasing demand for global environmental
protection, and the development of new batteries has been
expected.
Various kinds of large-capacity secondary batteries including
nickel-cadmium batteries, nickel-metal hydride batteries, lithium
batteries and sodium-sulfur batteries will come onto the market in
the future for various purposes. When managing batteries,
appropriate charging and discharging of batteries according to
their characteristics are essential to securing the soundness and
the long life of batteries. Each battery has specific
charge/discharge, temperature, rate and self-discharge
characteristics. These characteristics vary from battery to
battery.
In view of the convenience of using the battery, the residual
capacity of the battery must be known as accurately as possible.
Charging systems, temperature management and methods of determining
the residual capacity for each of those batteries have been
proposed. There have been known, for example, methods of detecting
the residual capacity on the basis of only voltage (Japanese Patent
Laidopen (Kokai) Nos. 58-85179 and 61-135335), a method of managing
the residual capacity on the basis of voltage and current (Japanese
Patent Laid-open (Kokai) No. 52-32542), methods of managing the
residual capacity on the basis of current and time (Japanese Patent
Laidopen Nos. 50-2130, 56-26271 and 59-28678), a method of managing
the residual capacity on the basis of measured capacitance
(Japanese Patent Laid-open (Kokai) No. 2-301974), a method of
managing the residual capacity on the basis of voltage, current and
temperature (Japanese Patent Laid-open (Kokai) No. 2-170372), a
method of managing the residual capacity on the basis of internal
resistance (Japanese Patent Laid-open (Kokai) No. 3-163375), a
method of managing the residual capacity that integrates current
and takes charge efficiency, discharge efficiency and temperature
characteristics into consideration (Japanese Patent Laid-open
(Kokai) No. 63-208773), and methods of determining the residual
capacity on the basis of the specific gravity of the electrolytic
solution (Japanese Patent Laid-open (Kokai) Nos. 56-24768, 57-88679
and 57-210578).
The capacity of a battery is dependent also on the charge and
discharge history of the battery. For example, the capacity of
nickel-cadmium batteries and nickel-metal hydride batteries
decreases due to memory effect if shallow discharge and charge are
repeated. In lithium batteries, lithium is accumulated on the
positive electrode and material forms on the negative electrode to
degrade the battery. If the charge/discharge balance is destroyed,
the power of the lithium battery must be discharged after due
consideration of the charge capacity. It is very important with
combination batteries to know the charged capacity. Since the
variation of the voltage of nickel-metal hydride batteries, as
compared with that of nickel-cadmium batteries, in the final stage
of charging is obscure, nickel-metal hydride batteries may be
overcharged causing drying of the electrolyte or increase in the
internal pressure and entailing safety problems unless
nickel-hydrogen batteries are charged after due consideration of
the discharge capacity. Since the capacity of batteries is greatly
dependent on temperature, charging rate and discharging rate, the
charge and discharge history of batteries must be taken into
account. Charging systems have been studied with such problems in
view. For example, a charging system disclosed in Japanese Patent
Laid-open (Kokai) No.4-308429 charges a battery after detecting the
fully discharged condition of the battery from the end voltage or
time to solve problems due to memory effect, and a charging system
disclosed in Japanese Patent Laid-open (Kokai) No. 61-81139 charges
a battery after detecting the fully discharged condition of the
battery from the end voltage or time to prevent overcharge.
A method of determining the residual capacity of a battery on the
basis of the specific gravity of the electrolyte is applicable only
to lead-acid batteries. Although a method of managing the residual
voltage on the basis of the voltage is effective when applied to
lead-acid batteries and lithium batteries the voltage of which
varies comparatively widely during charging and discharging, the
same is unsuitable for application to nickel-cadmium batteries and
nickel-metal hydride batteries the residual capacity of which
cannot be determined on the basis of only the voltage. It is
difficult to predict the residual capacity accurately on the basis
of current and temperature or on the basis of time besides on the
basis of voltage under operating condition where discharge rate
changes. When managing the residual capacity of a battery on the
basis of measured internal resistance or capacitance, it is
difficult to determine whether the increase of the internal
resistance is due to the deterioration of the battery or whether
the increase of the internal resistance is due to the exhaustion of
the battery unless the mode of deterioration of the battery is
precisely known. The management of the residual capacity on the
basis of integrated current, charging efficiency, discharging
efficiency and temperature characteristics allows one to predict
the residual capacity considerably accurately, however, it is
difficult to determine the residual capacity unless the capacity of
the battery is known when the capacity of the battery is reduced
greatly or the self-discharge of the battery is large. Since the
prior art methods of determining the residual capacity of batteries
are applicable only to specific batteries, respectively and hence
each battery requires a specific control.
The system proposed to eliminate memory effect (Japanese Patent
Laid-open (Kokai)No. 4-308429) and the system proposed to prevent
overcharge (Japanese Patent Laid-open (Kokai) No. 61-81139) are
intended to suppress the deterioration of a battery and to simplify
a charging method when the battery is used as the power supply of
portable apparatuses. Such a charge/discharge control method taking
the characteristics and the history of batteries has not been
proposed.
The difference between diurnal power demand and nocturnal power
demand has progressively increased in recent years, and diurnal
power demand in summer is approaching the upper limit of total
power generating ability of power stations. Power storage
techniques are effective means for solving problems attributable to
the wide daily and seasonal variation of power demand. For example,
electric power storage methods published in Denki Gakkai-shi, Vol.
111, No. 3, pp. 185-188 (1992) and such install large-capacity
secondary batteries in a substation to store (to charge) surplus
electric power generated in the nighttime and to deliver
(discharge) the stored power when power demand reaches a peak in
the daytime. However, nothing is mentioned about concrete means for
the maintenance of soundness of the secondary batteries and the
effective use of residual power.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a
distributed electric power storage system capable of maintaining
the soundness of secondary batteries and of effectively using
residual power.
The present invention provides a secondary battery electric power
storage system comprising a secondary battery connected to a load,
and a connection unit capable of being connected to a power system
and connected to the secondary battery and a plurality of loads,
characterized by a controller for controlling the connection unit
according to information about the secondary battery and the
plurality of loads.
At least either the plurality of loads or the secondary battery is
connected to the controller by an information transmitting means. A
secondary battery electric power storage system comprising:
a secondary battery connected to a load;
a detecting device for detecting a residual electric power of said
secondary battery;
a connection unit connected to a power source and to said secondary
battery;
a control unit connected to said connection unit; and
a signal line for transmitting information on said load and said
secondary battery to said control unit, wherein said connection
unit discharges electric power of said secondary battery to said
load when said residual electric power is larger than a
predetermined value and when the residual electric power is smaller
than the predetermined value, the electric power is discharged to
said power system or said load through said connection unit, prior
to charging of said secondary battery. A secondary battery electric
power storage system, wherein said secondary battery is connected
to a plurality of loads, and wiring is provided for signaling and
for transmitting information on said loads and said secondary
battery to said control unit, wherein said connection unit
distributes electric power of said secondary battery among said
loads when said residual electric power is larger than the
predetermined value. A secondary battery electric power storage
system comprising: a secondary battery connectable to a load; a
connection unit connectable to the secondary battery, said
connection unit being connectable to a power system and either a
plurality of loads or a plurality of electric power storage units;
a detecting device for detecting a residual electric power in the
secondary battery; and a control unit for controlling the
connection unit on the basis of information from the secondary
battery and at least one of the loads or electric power storage
units, wherein electric power in the secondary battery is
discharged to at least one of the loads when the residual electric
power is larger than the predetermined value, and the residual
electric power is discharged to the power system or to at least one
of the loads or electric power storage units when the residual
electric power is smaller than the predetermined value, prior to
charging of the secondary battery. A secondary battery electric
power storage system comprising: a secondary battery connected to a
load; a connection unit connectable to the secondary battery, said
connection unit being connectable to a power system and either a
plurality of loads or a plurality of electric power storage units;
a detecting device for detecting a residual electric power in the
secondary battery; and a control unit for controlling the
connection unit on the basis of information from the secondary
battery and at least one of the loads or electric power storage
units, wherein electric power in the secondary battery is
discharged to at least one of the loads when the residual electric
power is larger than the predetermined value, and the residual
electric power is discharged to the power system or to at least one
of the loads or electric power storage units when the residual
electric power is smaller than the predetermined value, prior to
charging of the secondary battery. A secondary battery electric
power storage system, wherein said connection unit is connected to
either a plurality of loads or a electric power storage units, and
said signal line for transmitting information on either said loads
or said electric power storage units and said secondary battery to
said control unit, wherein said connection unit distributes
electric power of said secondary battery among said either said
loads or said electric power storage units when said residual
electric power is larger than the predetermined value.
The secondary battery electric power storage system is
characterized by a signal line to transmit the information about
the operating condition of the plurality of loads to the
controller, and a signal line for transmitting information about
the surplus electric power of the secondary battery to the
controller.
The secondary battery electric power storage system may be provided
with at least either a measuring means associated with the
plurality of loads to measure information about operating condition
or a measuring means associated with the secondary battery to
measure information about the surplus electric power. The measuring
means may be ordinary measuring means (sensors) suitable for the
purpose of measurement.
The secondary battery electric power storage system is
characterized also by the connection of a plurality of electric
power storage units to the connection unit, and the connection of
the plurality of electric power storage units and the controller by
an information transmitting means.
The plurality of electric power storage units may be provided with
a measuring means for measuring the condition of power storage. The
measuring means may be an ordinary measuring means (sensor)
suitable for the purpose of measurement.
The present invention is applicable to, for example, the secondary
batteries of electric vehicles, the second batteries of hotwater
supply systems, secondary batteries for illumination, secondary
batteries for air-conditioning systems, buildings, factories,
apartment houses, cities and general residential buildings provided
with power supply facilities, such as emergency power supplies, and
transport facilities using electric power.
Desirably, the controller is provided with a clock or a timer.
The present invention provides also a secondary battery electric
power storage system comprising a secondary battery connected to
loads, and a connection unit capable of being connected to a power
system, and connected to the secondary battery and at least either
a plurality of loads or a plurality of electric power storage
units, characterized in that a load to which power is to be fed and
the capacity are selected on the basis of information about the
secondary battery, the plurality of loads and the plurality of
electric power storage units, and the surplus electric power
remaining in the secondary battery after feeding the power stored
in the secondary battery to the loads is fed to the selected
load.
A load to which electric power is to be fed and the capacity are
selected on the basis of at least one of information about the
surplus electric power of the secondary battery, information about
the operating condition of the plurality of loads and information
about the power storage condition of the electric power storage
units, and power is fed to the selected load.
The electric power storage system of the present invention may
employ the following secondary battery electric power storage
system for controlling the power system or operations for charging
and discharging electric power stored in a secondary battery and a
plurality of electric power storage units.
The present invention provides an electric power storage system
comprising a connection unit connectable to a power system, and
connected to at least either a plurality of loads or a plurality of
electric power storage units, a controller for controlling the
connection unit, and a connecting means for connecting a secondary
battery, characterized in that the controller controls the
connection unit on the basis of information from at least one of
the plurality of loads, the plurality of electric power storage
units and the connecting means.
The secondary battery electric power storage system is
characterized also by an information transmitting means interposed
between at least one of the plurality of loads, the plurality of
electric power storage units and the connecting means, and the
controller. A secondary battery is connected for charging and
discharging to the secondary battery power storage system to use
power effectively.
At least one of the plurality of loads, the plurality of electric
power storage units and the connecting means is provided with
measuring means for measuring various values, associated with the
information transmitting means. The information transmitting means
transmits information measured by the measuring means.
The secondary battery to be employed in the present invention is
provided with a measuring means for measuring the amount of
electric power charged in the secondary battery and the amount of
electric power discharged from the secondary battery, and a
computer that calculates the residual power of the secondary
battery.
More concretely, the secondary battery electric power storage
system is provided with a measuring means for measuring the
condition of the secondary battery, and a computer provided with a
memory capable of storing measured data measured by the measuring
means, arithmetic programs and information including data on the
characteristics of the secondary battery, and a controller for
processing the information stored in the memory and information
given thereto from external devices, and it is desirable that the
information stored in the secondary battery can be transmitted by
the information transmitting means.
The secondary battery to be used by the present invention is at
least one of secondary batteries including lead-acid batteries,
nickel-cadmium batteries, nickel hydrogen batteries and lithium
batteries, or any combination of these secondary batteries. The
secondary battery is provided with a storage device capable of
storing at least the measured data and the arithmetic programs.
The plurality of electric power storage units are at least a
plurality of secondary batteries, such as lead-acid batteries,
nickel-cadmium batteries, nickel-metal hydride batteries or lithium
batteries, a plurality of heat storage and heat exchanger systems,
a plurality of superconducting type electric power storage systems,
or any combinations of these batteries and electric power storage
systems.
The connection unit is provided with an ac-dc conversion means and
a switching means. The ac-dc conversion means, such as a thyristor,
enables the control of power factor. The switching means switches
circuits connecting the power system to the secondary battery, the
plurality of loads and the plurality of electric power storage
units depending on the operating condition of the surrounding
loads. When necessary, the secondary battery electric power storage
system is provided with a power measuring means for measuring the
amount of power fed or received through the connection unit, such
as a measuring means for measuring the amount of charged electric
power and the amount of discharged electric power, and an
information transmitting means for transmitting the measured data
to the controller for controlling the connection unit. The
secondary battery or the plurality of electric power storage units
may be provided with a measuring means for measuring the amount of
charged electric power and that of discharged electric power.
The means for measuring the amount of charged electric power and
that of discharged electric power is a sensor, such as an ammeter
voltmeter or a Coulomb meter.
The controller for controlling the connection unit is capable of
selecting a load to which the secondary battery and the electric
power storage units feed power on the basis of information about
the amount of the surplus electric power of the secondary battery,
operating condition of the plurality of loads and the power storage
condition of the plurality of electric power storage units. The
secondary battery power storage system may be provided with a
calculating means for calculating the amount of charged electric
power and that of discharged electric power on the basis of
information from the secondary battery, the plurality of loads and
the plurality of electric power storage units and with a memorizing
means.
The information about the operating condition of the plurality of
loads is information about power necessary for operating the
plurality of loads or the current power demand of the plurality of
loads. Preferably, information about scheduled operating time and
such is used.
The information transmitting means is, for example, a signal line.
Information may be transmitted by means of radiowaves.
The information about the surplus electric power is, for example, a
measured amount of surplus electric power, data on optimum charge
and discharge characteristics (charge and discharge modes) and the
charge and discharge history of the secondary battery.
The plurality of loads has at least one load, and the plurality of
electric power storage units has at least one electric power
storage unit.
A secondary battery electric power storage system in accordance
with the present invention comprises a secondary battery mounted on
a load, such as an electric vehicle, a connection unit capable of
being connected to a power system, such as a charge stand, and
connected to the secondary battery, a plurality of electric power
storage units capable of being connected to the power system, and
connected through the connection unit in parallel to the secondary
battery, a plurality of loads connected to the plurality of
electric power storage unit, a plurality of loads connected to the
connection unit.
The connection unit capable of being connected to the power system
may be connected to the secondary battery, the plurality of loads
and the plurality of electric power storage units.
The present invention is capable of controlling charge and
discharge of the plurality of loads, the plurality of electric
power storage units and the secondary battery on the basis of
information from the plurality of loads, the plurality of electric
power storage units and the secondary battery.
Concretely, necessary power can be measured by a power measuring
means on the basis of the operating condition of the plurality of
loads. The surplus electric power of the secondary battery, the
power storage condition of the plurality of electric power storage
units, and the discharge characteristic and the available capacity
of the battery are determined, a load to which power is to be fed
is selected from among the plurality of loads or the plurality of
electric power storage units, and the surplus electric power can be
fed through the connection unit to the selected load.
Naturally, power may be stored in the electric power storage units
and then power may be fed from the electric power storage units to
the plurality of loads.
Thus the surplus electric power can be effectively distributed and
the residual power can be discharged after determining the amount
of available power from the residual power. Therefore, the
soundness of the battery can be secured and discharge control can
be efficiently carried out.
When charging the secondary battery, the residual capacity of the
secondary battery is determined before charging, and whether the
secondary battery is to be charged or whether the secondary battery
is discharged is determined on the basis the residual capacity of
the secondary battery.
The intrinsic optimum charge and discharge characteristics of the
secondary battery, and the power demand of the plurality of loads
or the power storage condition of the plurality of electric power
storage units are measured and a load to which power is to be fed
is selected. When the plurality of loads has a plurality of loads,
it is preferable to measure the power demand of each load. When the
plurality of electric power storage units has a plurality of
electric power storage units, it is preferable to determine the
power storage condition of each electric power storage unit.
For example, a load to which power is to be fed and the amount of
power to be fed are determined selectively after examining power
demand to see if the power demand can be supplied by the secondary
battery and to see if the output current density (large-current
discharge or small-current discharge) is appropriate to the
secondary battery, and then the connection unit connects the
secondary battery to the selected load to feed power to the latter
by orders of controller.
When the timer is used, the soundness of the battery can be secured
and electric power can be efficiently used by accumulating electric
power in night period rate hours in the night and using the
accumulated electric power in the daytime.
More concretely, for example, the secondary battery is charged
through the connection unit with electric power during night period
rate hours, the surplus electric power of the secondary battery is
fed (discharged) to the connection unit connected to the secondary
battery, and electric power is fed (discharged) through the
connection unit to the plurality of electric power storage units,
the plurality of loads connected to the plurality of electric power
storage units and the plurality of loads connected to the
connection unit in day period rate hours. Inexpensive night period
rate electric power can be stored and used, and then the stored
electric power can be sold through the connection unit that can be
connected to the secondary battery to consumers in day. When
selling the stored electric power, it is preferable to determine
the power demand of the plurality of loads on the basis of
information about operating condition received from a plurality of
electric power storage units or the plurality of loads by the
controller connected to the connection unit connected to the
secondary batteries, to select a load to which electric power is to
be fed, taking into consideration the available power capacity of
the secondary battery, and to feed the surplus electric power of
the secondary battery through the connection unit to the selected
load.
The soundness and the original power capacity of the battery can be
known by discharging the surplus electric power. The original power
capacity of the battery can be known from charged capacity after
discharge of nearly 100% of the full capacity of the battery
(nearly exhausted state). It is desirable, if possible, to know the
capacity of the battery every time the battery is discharged or
charged to know the soundness of the battery.
Desirably, the secondary battery employed in the present invention
is provided with, for example, measuring means (sensors) for
acquiring data, an A/D converter for converting the data acquired
by the measuring means and giving the converted data to a computer,
a memory storing data on the charge and discharge history,
arithmetic programs, an indication program and data on the standard
characteristics, and a controller for processing the information
stored in the memory and information placed into the memory by
external devices. These components may be integrally combined with
the battery.
For example, the arithmetic programs and the indication program are
an arithmetic program defining a procedure for determining
discharged capacity by integrating discharge current, an arithmetic
program defining a procedure for determining charged capacity by
integrating charge current, an arithmetic program defining a
procedure for determining converted charged capacity, i.e.,
available capacity under a discharge rate and a temperature
condition at the time when discharge current data is received from
the discharge efficiency and the temperature characteristic,
determined by converting charged capacity in a real-time mode, an
arithmetic program defining a procedure for determining surplus
electric power discharged capacity by integrating surplus electric
power discharge current data, and an indication program defining a
procedure for indicating the surplus electric power discharged
capacity determined by the procedure defined by the arithmetic
program.
Discharge current data, discharge voltage data and discharge
temperature data on the discharge history, are measured by
measuring means (sensors) when the secondary battery feeds electric
power to the loads, and the measured data are transferred through
an A/D converter to a computer provided with a memory and a
controller. Charging current data, charge voltage data and charge
temperature data on the charge history, are measured when the
secondary battery is charged with electric power through the
connection unit connected to the secondary battery in the night,
and the measured data are transferred through the A/D converter to
the computer. Surplus electric power discharge current data,
surplus electric power discharge voltage data and surplus electric
power discharge temperature or surplus electric power discharge
history, are measured by sensors when the secondary battery
discharges surplus electric power through the connection unit
connected to the secondary battery, and the measured data are
transferred through the A/D converter to the computer. The
soundness of the battery can be known from those measured data. A
discharged capacity discharged to the loads and a surplus electric
power discharged capacity discharged to the connection unit can be
known from the discharge current data and the surplus electric
power discharge current, and the discharge operation of the
secondary battery can be controlled so that the battery may not be
discharged to a voltage below the final discharge voltage, i.e., so
that the secondary battery may not be overdischarged, by using the
discharge voltage data and the surplus electric power discharge
voltage data. The charged capacity charged into the secondary
battery can be known from the charge current data. The increase of
the voltage of a lithium battery to its final charge voltage can be
known from the charge voltage data and hence the overcharge of the
lithium battery can be prevented. The final charge voltage of a
nickel-cadmium battery can be known from the variation of the
voltage in the final stage of charging operation and hence charging
can be terminated before the nickel-cadmium battery is
overcharged.
Unlike a nickel-cadmium battery, a nickel-metal hydride battery has
a small voltage variation in the final stage of charging.
Therefore, it is desirable to take temperature variation into
consideration in addition to voltage variation in determining the
time to stop charging to prevent overcharge. As regards other kinds
of batteries, abnormal rise of temperature is an indication of the
abnormal condition of the batteries. Since charging efficiency and
discharging efficiency are dependent on temperature, it is
preferable to use temperature data in correcting charged capacity
and discharged capacity because charged capacity and discharged
capacity are dependent on temperature.
Desirably, the aforesaid data are corrected for charging rate,
discharging rate and temperature. The standard characteristic data,
such as the inherent charging efficiency, discharging efficiency
and temperature characteristic, of the secondary battery are stored
in the memory. The charge current data and the discharge current
data given to the A/D converter are integrated to determine charged
capacity and discharged capacity. The charged capacity is converted
in a real-time mode into a converted charged capacity, i.e., a
capacity available at the discharge rate and under the temperature
condition at the time when the discharge current data is obtained,
on the basis of the charging efficiency, the discharging efficiency
and the temperature characteristic stored in the memory. The
discharged capacity is subtracted from the converted charged
capacity determined in the real-time mode to determine a residual
capacity. Thus, the residual capacity at the current temperature
and at the current discharge rate can be indicated. For example,
since the possible distance of travel of an electric vehicle is
dependent on the condition of the road, namely, the possible
distance of travel along a downhill is longer than that along an
uphill, the possible distance of travel can be estimated on the
basis of the discharging efficiency according to the condition of
the road, and the estimated possible distance of travel can be
indicated.
Since the discharging efficiency is dependent on temperature and is
subject to seasonal variation, a possible distance of travel
determined by taking into consideration the temperature
characteristic can be indicated.
Surplus electric power discharge capacity can be determined by
integrating the surplus electric power discharge current data and
the surplus electric power discharge capacity can be indicated.
Since the surplus electric power discharge capacity is selling
electric energy for sale, the surplus electric power discharge
capacity is transferred to the connection unit connected to the
secondary battery and the power system, the plurality of electric
power storage units or the plurality of loads. Preferably the
connection unit is capable of measuring and indicating the
capacity.
It is desirable to discharge the surplus electric power from the
secondary battery in a mode conforming to optimum discharge
conditions for the secondary battery to secure the soundness of the
secondary battery and to extend the cycle life of the secondary
battery. It is preferable to discharge the surplus electric power
from the secondary battery in conformance with optimum discharge
conditions stored in the memory when the surplus electric power is
discharged to the connection unit connected to the secondary
battery and connectable to the power system. The optimum charge and
discharge conditions are pieces of information about a discharge
method specifying, for example, at least one of maximum discharge
capacity, discharge current, discharge voltage, discharge time and
a lower limit voltage. More concretely, discharging conditions as
battery characteristic data including discharge modes, such as a
constant-current discharge mode, a constant-voltage discharge mode,
a pulse discharge mode and combinations of those discharge modes,
an optimum current, an optimum voltage, and discharge cutting mode,
such as a time-cut mode and a voltage-cut mode, is stored
beforehand in the memory. Charging information specifying charging
conditions similar to the discharging conditions are used for
charging. If even one of the batteries of a battery set is
deteriorated, the deteriorated battery will be overdischarged and
the cycle life of the same is shorted significantly. It is
desirable to use a control method determined by taking into
consideration the type the scale and the security of the battery to
execute time-cut or voltage-cut on the basis of monitored voltage
variation.
The available discharge capacity that can be discharged in the
future (next) discharge cycle and the cycle life of the secondary
battery can be estimated from the past charge capacities of the
secondary battery and the mode of change of charged capacity.
Causes of reduction of the capacity of the secondary battery, such
as the exhaustion of the electrolyte, the deterioration of the
positive electrode and the deterioration of the negative electrode,
can be determined from the mode of reduction of the capacity.
Overdischarge of the battery can be prevented by determining the
available discharge capacity and the possible discharge time of the
battery and discharging the surplus power accordingly. Similarly,
the secondary battery is charged in a mode conforming to the
optimum charge conditions stored in the memory when charging the
secondary battery through the connection unit at night, in which
overcharge of the secondary battery can be prevented by determining
the available discharge capacity and the possible discharge time,
and charging the secondary battery accordingly.
It is desirable to determine beforehand surplus electric power
discharge hours. For example, the discharge of the surplus electric
power is interrupted when the surplus electric power is not
discharged completely. The charge capacity determined in the
preceding charge cycle is used as charge capacity. Preferably, the
surplus electric power discharge capacity is determined on the
basis of the residual capacity, taking into consideration the type
of the battery to secure the soundness of the battery. For example,
since a nickel-cadmium battery and a nickel-metal hydride battery
are subject to large self-discharge and have a memory effect, it is
preferable to discharge 95% to 100% of a discharge capacity in a
mode conforming to optimum discharge conditions revised for the
future available discharge capacity of the batteries when the
residual capacity is in the range of 0% to 85% of the charge
capacity. When the residual capacity is 85% or above of the charge
capacity, it is better not to discharge the surplus electric power.
Thus, charging and discharging are simplified and the memory effect
can be prevented. Since a lithium battery or the like is subject to
a comparatively small self-discharge and the cycle life of a
lithium battery or the like is reduced when the same is discharged
deep, it is desirable to discharge the surplus electric power
corresponding to 80% to 95% of the discharge capacity in a mode
conforming to optimum discharge conditions revised for the
available discharge capacity of the battery, when the residual
capacity is in the range of 5% to 80% of the charge capacity. When
the residual capacity is less than 5% of the charge capacity, it is
better not to discharge the surplus electric power because further
discharge reduces the cycle life of the battery. When the residual
capacity is 80% or above of the charge capacity, it is desirable
not to discharge the surplus electric power to simplify charging
and discharging.
The whole capacity of battery can be known at every discharge and
the residual capacity of the battery can be accurately determined
when the surplus electric power is discharged with the performance
of the battery being taking into consideration. The cycle life of
the battery and the future capacity of the battery can be estimated
from the whole capacity of the battery and the residual capacity.
Accordingly, charge/discharge control can be carried out according
to the change of the performance of the battery and thereby the
soundness of the battery is enhanced.
Charging of the battery with the inexpensive night period rate
electric power in the nighttime and using the surplus electric
power in the daytime are economically advantageous.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a secondary battery electric power
storage system in accordance with the present invention;
FIG. 2 is a block diagram of a secondary battery electric power
storage system in accordance with the present invention;
FIG. 3 is a block diagram of a secondary battery electric power
storage system in accordance with the present invention;
FIG. 4 is a block diagram of a secondary battery electric power
storage system in accordance with the present invention;
FIG. 5 is a flow chart of a procedure for controlling a secondary
battery, in accordance with the present invention;
FIG. 6 is a graph showing the charge/discharge cycle
characteristics of secondary batteries in a second embodiment
according to the present invention;
FIG. 7 is a graph comparatively showing residual capacity
indications and actual residual capacities in the second embodiment
according to the present invention;
FIG. 8 is a graph showing the charge/discharge cycles of secondary
batteries in a third embodiment according to the present
invention;
FIG. 9 is a graph comparatively showing residual capacity
indications and residual capacities in a comparative example 1;
and
FIG. 10 is a graph showing the charge/discharge cycle
characteristics of secondary batteries in the comparative example
1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will be described in
detail hereinafter.
The embodiments are illustrative and not restrictive.
First Embodiment
FIG. 1 shows a secondary battery electric power storage system in a
first embodiment according to the present invention. Although the
first embodiment is one of the best modes for carrying out the
invention, the present invention is not limited thereto. Referring
to FIG. 1, a secondary battery load 1, and a connection unit 2
connectable to a power system are connected to a secondary battery
3. A plurality of electric power storage units 4 are placed in
parallel combination with the connection unit 2 connected to a
power supply system. A plurality of loads 5 are connected to the
charge/discharge unit 2 or the electric power storage units 4. A
signal line 30 indicated by broken lines, is connected to a
controller 7 included in the connection unit 2. Detecting device 40
detects residual electric power in the secondary battery.
When necessary, the secondary battery electric power storage system
is provided with a means, not shown in FIGS. 1 to 4, for supplying
electric power directly from the power supply system to the loads 5
or the electric power storage units 4, bypassing the connection
unit 2. When the secondary battery electric power storage system is
provided with such a means, it is desirable that the secondary
battery electric power storage system is provided with a signal
line for transmitting signals representing measured values, such as
the amount of electric power used to the controller 7 of the
connection unit 2. Amounts of electric power applied to and
delivered from the secondary battery 3 and the electric power
storage units 4 are measured by measuring devices and measured data
is sent through the signal line to the controller 7 of the
connection unit 2.
The secondary battery 3, the electric power storage units 4 and the
loads 5 are provided with sensors (measuring means).
First the secondary battery 3 is connected to the charge/discharge
unit 2 to charge the secondary battery 3 with night period rate
electric power. After the secondary battery has been charged, the
secondary battery 3 is connected to the secondary battery load 1 to
discharge the secondary battery 3. After discharging, the secondary
battery 3 is disconnected from the secondary load 1 and connected
to the connection unit 2 to discharge the surplus electric power of
the secondary batter 3 in the day period rate hours. A controller 6
included in the secondary battery 3 controls the secondary battery
3 for discharging the surplus electric power remaining after
charging the secondary battery load 1, i.e., the residual capacity
in a mode conforming to optimum discharging conditions in the day
period rate hours. The discharge of the surplus electric power is
stopped in the night period rate hours and the secondary battery is
charged. In this state, the charge capacity does not correspond to
the capacity of the battery because the battery has the residual
capacity. Therefore, the charge capacity used in the preceding
charge cycle is used as the charge capacity to be taken into
consideration in indicating the residual capacity. The controller 7
of the connection unit 2 measures the amounts of electric power
required by the electric power storage units 4 or the loads 5,
selects the electric power storage unit or the load and controls
the secondary battery 3 to supply the surplus electric power to the
selected electric power storage unit or the load.
FIG. 2 shows an embodiment of the present invention. In this
embodiment, a secondary battery load 1, and a connection unit 2
connectable to a power system are connected to a secondary battery
3, and electric power storage units 4 are placed in parallel
combination with the connection unit 2.
FIG. 3 shows an embodiment of the present invention. In this
embodiment, a secondary battery load 1 and a connection unit 2
connectable to a power system are connected to a secondary battery
3, and loads 5 are connected to the connection unit 2. FIG. 4 shows
an embodiment of the present invention. In this embodiment, a
secondary battery load 1 and a connection unit 2 connectable to a
power system are connected to a secondary battery 3, and series
circuits each of an electric power storage unit 4 and a load 5 are
placed in parallel connection with the connection unit 2.
Second Embodiment
FIG. 5 is a flow chart of a control procedure to be carried out by
the controllers 6 of the secondary batteries 3 of FIGS. 1 to 4. The
control procedure will be described hereinafter with reference to
FIGS. 1 to 5. The secondary battery 3 is provided with the
controller 6, an A/D converter 8 and a memory 9. The memory 9 is
capable of storing standard characteristic data on the intrinsic
characteristics of the secondary battery 3 including charging
efficiency 10, discharging efficiency 11, temperature
characteristics 12 and optimum charge and discharge conditions 13.
The optimum charge and discharge conditions 13 specify charge and
discharge modes, such as a constant-current charge mode, constant
discharge mode, a constant-voltage discharge mode and a
constant-voltage discharge mode, currents and voltages, cut
voltages, charge capacities, discharge capacities, charge times and
discharge times.
When the secondary battery 3 is connected to the charge/discharge
unit 2 for charging, the secondary battery 3 is controlled for
charging according to the optimum charge conditions. At every
charge cycle, an A/D converter receives charge operation data
including charge current data 14, charge voltage data 15 and charge
temperature data 16. The charge voltage data 15 is necessary for
terminating charging at a cut voltage. The charge temperature data
16 is used for detecting the final charge stage for a nickel-metal
hydride battery. The temperature data 15 is used also for detecting
the abnormal condition of the battery when the temperature of the
battery rises abnormally. The charge current data 14 is integrated
to obtain a charged capacity.
When the secondary battery 3 is connected to the secondary battery
load 1 and electric power stored in the secondary battery 3 is
discharged into the secondary battery load 1, the A/D converter 8
receives discharge operation data including discharge current data
17, discharge voltage data 18 and discharge temperature data 19.
The discharge voltage data 18 is necessary for terminating
discharge at a cut voltage. The discharge current data 17 is
integrated to obtain a discharged capacity. The discharged capacity
is converted in a real-time mode for a discharging rate and a
temperature represented by the discharge temperature data 19 into
an available discharge capacity, i.e., converted charge capacity,
for determining a residual capacity. The residual capacity is
obtained by subtracting the discharged capacity from the converted
charge capacity.
When the secondary battery 3 is connected to the connection unit 2
to discharge the surplus electric power, the discharge operation of
the secondary battery 3 is controlled according to the optimum
charge and discharge conditions 13. At every surplus electric power
discharging operation, the A/D converter 8 receives surplus
electric power discharge operation data including surplus electric
power discharge current data 20, surplus electric power discharge
voltage data 21 and surplus electric power temperature data 22. The
surplus electric power discharge current data 20 is integrated to
obtain a surplus electric power discharge capacity, and the surplus
electric power discharge capacity is indicated. The surplus
electric power discharge capacity can be transferred through the
connection unit 2 to the electric power storage units 4 and the
loads 5. When selling the surplus electric power, it is preferable
to indicate an amount of money corresponding to the surplus
electric power when necessary.
FIG. 6 shows the charge and discharge cycle characteristics of
secondary batteries and FIG. 7 shows the variation of the
difference between residual capacity indication and actual residual
capacity with the number of charge and discharge cycles. The
capacities of a lead-acid battery B, a nickel-cadmium battery D, a
nickel-hydrogen battery A and lithium battery E decrease slightly
as the number of charge and discharge cycles increases, and the
possible numbers of charge and discharge cycles for those batteries
are not less than 1000. The difference between the residual
capacity indication and the actual residual capacity is very
small.
Third Embodiment
When a secondary battery 3 is a nickel-cadmium battery or a
nickel-metal hydride battery, a controller 6 controls the secondary
battery 3 for discharging so that 95% to 100% of a discharge
capacity corresponding to an available discharge capacity is
discharged in a mode conforming to optimum discharge conditions
when the residual capacity is 0 to 85% of the charge capacity of
the secondary battery 3.
If the residual capacity is 85% or above of the charge capacity,
surplus electric power discharge is not performed. When the
secondary battery 3 is a lithium battery, the controller 6 controls
the secondary battery 3 so that 80% to 95% of a discharge capacity
corresponding to an available discharge capacity is discharged in a
mode conforming to optimum discharge conditions when the residual
capacity is 5% to 80% of the charge capacity. When the residual
capacity is 5% or below of the charge capacity, surplus electric
power discharge is not performed. When the residual capacity is 80%
or above of the charge capacity, surplus electric power discharge
is not performed.
FIG. 8 shows the charge and discharge cycle characteristics of
batteries under the control operation of the controller. The
capacities of a nickel-cadmium battery, a nickel-metal hydride
battery and a lithium battery decrease scarcely as the number of
charge and discharge cycles increases. The possible numbers of
charge and discharge cycles for those batteries are not less than
1200.
COMPARATIVE EXAMPLE 1
In a secondary battery electric power storage system in a
comparative example 1, a secondary battery load 1 and a connection
unit 2 are connected to a secondary battery 3. The secondary
battery 3 is connected to the connection unit 2 and the secondary
battery 3 is charged with night period rate electric power. Then,
the secondary battery 3 is connected to the secondary battery load
1 and the electric power stored in the secondary battery 3 is
discharged into the secondary battery load 1. After discharging,
the secondary battery 3 is disconnected from the secondary battery
load 1 and is connected to the connection unit 2 to charge the
secondary battery 3 with night period rate electric power. The
residual capacity of the secondary battery is determined by
subtracting a discharged capacity from an initial capacity. FIG. 9
shows the difference between residual capacity indication and
actual residual capacity. As is obvious from FIG. 9, the difference
increases as the number of charge and discharge cycles increases
and, consequently, accurate residual capacity indication is
impossible. FIG. 10 shows the charge and discharge cycle
characteristics of batteries. As is obvious from FIG. 10, the
capacities of a lead-acid battery, a nickel-cadmium battery, a
nickel-metal hydride battery and a lithium battery decrease greatly
as the number of charge and discharge cycles increases, and the
lives of those batteries are in the range of 500 to 700 charge and
discharge cycles.
As is apparent from the foregoing description, according to the
present invention, the soundness of the battery can be secured, and
charging and discharging are carried out efficiently. The secondary
battery can be charged with inexpensive night period rate electric
power in the night and the surplus electric power can be supplied
to loads in the day time.
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