U.S. patent application number 09/781135 was filed with the patent office on 2001-08-16 for discharge circuit and duty ratio setting method.
Invention is credited to Takemoto, Tsuyoshi.
Application Number | 20010013767 09/781135 |
Document ID | / |
Family ID | 18558939 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013767 |
Kind Code |
A1 |
Takemoto, Tsuyoshi |
August 16, 2001 |
Discharge circuit and duty ratio setting method
Abstract
A battery controller 6 is connected to a DC/DC converter 3. The
battery controller 6 checks the capacities of a battery 4 and a
battery 5, calculates a duty ratio between the battery 4 and the
battery 5 based on the capacities to determine a switching timing
in which a plurality of switching elements are to be switched, and
sets the duty ratio in the DC/DC converter 3.
Inventors: |
Takemoto, Tsuyoshi;
(Yamagata, JP) |
Correspondence
Address: |
SUGHRUE, MION, ZINN, MACPEAK & SEAS
2100 Pennsylvania Avenue, N.W.
Washington
DC
20037-3202
US
|
Family ID: |
18558939 |
Appl. No.: |
09/781135 |
Filed: |
February 12, 2001 |
Current U.S.
Class: |
320/132 |
Current CPC
Class: |
H02J 7/0013 20130101;
H02J 7/0025 20200101; H02M 3/158 20130101; H02J 2207/20 20200101;
H02J 2007/0067 20130101 |
Class at
Publication: |
320/132 |
International
Class: |
H02J 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 14, 2000 |
JP |
2000-034636 |
Claims
What is claimed is:
1. A discharge circuit comprising at least two batteries, a
plurality of switching elements connected to said batteries, and a
DC/DC converter controlling ON/OFF states of said plurality of
switching elements, wherein a duty ratio setting unit is connected
to said DC/DC converter, said duty ratio setting unit checking
capacities of said batteries, calculating a duty ratio based on a
battery capacity ratio calculated from the capacities of said
batteries to determine a switching timing in which said plurality
of switching elements are to be switched, and setting the duty
ratio in said DC/DC converter.
2. The discharge circuit as defined by claim 1, wherein said duty
ratio setting unit checks remaining capacities of said batteries,
calculates a new duty ratio based on the battery capacity ratio
calculated from the remaining capacities, and updates the duty
ratio set in said DC/DC converter.
3. A duty ratio setting method comprising the steps of: checking
capacities of at least two batteries; calculating a battery
capacity ratio from the battery capacities and, based on the
battery capacity ratio, calculating a duty ratio which determines a
switching timing in which a plurality of switching elements
connected to said batteries are to be switched; and transmitting
the duty ratio to a DC/DC converter as a signal to set the duty
ratio in a DC/DC converter.
4. The duty ratio setting method as defined by claim 3, further
comprising the steps of: checking remaining capacities of said
batteries when the battery capacity ratio varies caused by
discharge of the batteries; calculating a remaining capacity ratio
between said batteries based on the remaining capacities of said
batteries to calculate a new duty ratio from the remaining capacity
ratio of the batteries; and transmitting the calculated new duty
ratio to the DC/DC converter as a signal to change the duty ratio
that is set in the DC/DC converter.
5. A computer readable program product which sets a duty ratio,
said program causing a processor to execute the steps of: checking
capacities of at least two batteries; calculating a duty ratio
which determines a switching timing in which a plurality of
switching elements connected to said batteries are to be switched;
and transmitting the duty ratio to a DC/DC converter as a signal to
set the duty ratio in the DC/DC converter.
6. The program product, further comprising the steps of: checking
remaining capacities of said batteries when the battery capacity
ratio varies caused by discharge of the batteries; and calculating
a remaining capacity ratio between said batteries based on the
remaining capacities of said batteries to calculate a new duty
ratio from the remaining capacity ratio of the batteries.
7. A medium carrying thereon said program as defined by claim 5.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a discharge circuit and a
duty ratio setting method.
BACKGROUND OF THE INVENTION
[0002] Conventionally, a multiple-battery power supply method used
for a data processing apparatus (or unit) supplies power
simultaneously from a plurality of batteries with the same
characteristics.
[0003] Referring to FIG. 4, a discharge circuit using the
conventional power supply method will be described.
[0004] The conventional discharge circuits shown in FIG. 4
comprises a battery 4 and a battery 5, which have the same
characteristics, and a data processing apparatus 8 which comprises
a DC/DC converter 3, a switching element 9 connected to the DC/DC
converter 3, and a unit load 7.
[0005] Turning on the switching element of the conventional
discharge circuit with the configuration described above causes the
battery 4 and the battery 5 to discharge simultaneously, this
configuration can decrease the discharge rate of each battery and
increase battery efficiency.
SUMMARY OF THE DISCLOSURE
[0006] However, various problems have been encountered in the art
in the course of investigations toward the present invention. That
is, if a plurality of batteries, each with its own characteristics,
is connected to the conventional discharge circuit described above,
the battery with the highest voltage discharges first. Therefore,
the discharge ratio between the battery 4 and the battery 5 depends
on the voltage characteristics. That is, the battery 4 or the
battery 5, whichever is higher in voltage, discharges first. As a
result, the problem with the conventional circuit is that the
battery with the highest voltage loses its capacity first and,
after that, the battery with the lowest voltage is subjected to
discharge alone.
[0007] Therefore, the conventional discharge circuit does not make
the best use of simultaneous discharging, and during discharging,
the remaining battery capacity varies among batteries.
[0008] The present invention seeks to solve the problems associated
with the prior art described above. It is an object of the present
invention to provide a discharge circuit and a control method of
discharging that allow a plurality of batteries a simultaneous
discharging regardless of their battery voltages. Other objects of
the present invention will become apparent from the entire
disclosure.
[0009] According to a first aspect of the present invention, there
is provided a discharge circuit comprising at least two batteries,
a plurality of switching elements connected to the batteries, and a
DC/DC (Direct Current/Direct Current) converter controlling ON/OFF
states of the plurality of switching elements, wherein a duty ratio
setting unit is connected to the DC/DC converter, the duty ratio
setting unit checking capacities of the batteries, calculating a
duty ratio based on a battery capacity ratio calculated from the
capacities of the batteries to determine a switching timing in
which the plurality of switching elements are to be switched, and
setting the duty ratio in the DC/DC converter.
[0010] The discharge circuit with this configuration sets the duty
ratio in the DC/DC converter based on the battery capacity ratio
calculated from the capacities of the batteries. Therefore, the
batteries are simultaneously discharged regardless of their
voltages, and the plurality of batteries may be used up at the same
time.
[0011] According to a second aspect of the present invention, there
is provided a discharge circuit, wherein the duty ratio setting
unit checks remaining capacities of the batteries, calculates a new
duty ratio based on the battery capacity ratio calculated from the
remaining capacities, and updates the duty ratio set in the DC/DC
converter.
[0012] In accordance with the second aspect, the duty ratio may be
changed based on the capacity ratio. Therefore, it is assured that
the batteries are simultaneously discharged regardless of their
voltages, and the plurality of batteries may be used up at the same
time.
[0013] According to a third aspect of the present invention, there
is provide a duty ratio setting method comprising the steps of:
detecting capacities of at least two batteries; calculating a
battery capacity ratio from the battery capacities followed by
calculating, based on the battery capacity ratio, a duty ratio
which determines a switching timing in which a plurality of
switching elements connected to the batteries are to be switched;
and transmitting the duty ratio to a DC/DC converter as a signal to
set the duty ratio in the DC/DC converter.
[0014] In accordance with the duty ratio setting method comprising
those steps, the duty ratio based on the battery capacity ratio
calculated from the capacities of the batteries may be set (and
undated) in the DC/DC converter. Therefore, the batteries may be
simultaneously discharged regardless of their voltages, and the
plurality of batteries may be used up at the same time.
[0015] According to fourth aspect of the present invention, the
duty ratio setting method further comprises the steps of: checking
remaining capacities of the batteries when the battery capacity
ratio varies caused by discharge of the batteries; calculating a
remaining capacity ratio between the batteries based on the
remaining capacities of the batteries to calculate a new duty ratio
from the remaining capacity ratio of the batteries; and
transmitting the calculated new duty ratio to the DC/DC converter
as a signal to change the duty ratio that is set in the DC/DC
converter.
[0016] In accordance with the duty ratio setting method of the
fourth aspect, the new duty ratio based on the remaining capacity
ratio calculated from the capacities of the batteries is set in the
DC/DC converter to change (update) the old duty ratio. Therefore,
the batteries may be simultaneously discharged regardless of their
voltages, and the plurality of batteries may be used up at the same
time.
[0017] According to a fifth aspect, there is provided a computer
readable program product which sets a duty ratio, the program
causing a processor to check capacities of at least two batteries;
calculate a duty ratio which determines a switching timing in which
a plurality of switching elements connected to the batteries are to
be switched; and send the duty ratio to a DC/DC converter as a
signal to set the duty ratio in the DC/DC converter.
[0018] The duty ratio setting program comprising those steps sets
the duty ratio, which is based on the capacity ratio of the
batteries calculated from the capacities of the batteries, in the
DC/DC converter. Therefore, the batteries may be simultaneously
discharged regardless of their voltages, and the plurality of
batteries may be used up at the same time.
[0019] The program product is carried by a medium, typically a
recording medium, which, however, includes a static/non-static or
dynamic medium, also including a carrier wave carrying the program
via transmission lines or networks.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a diagram showing the configuration of a first
embodiment of a discharge circuit according to the Present
invention.
[0021] FIG. 2 is a diagram showing a timing in which a DC/DC
converter in the first embodiment of the present invention controls
switching operation.
[0022] FIG. 3 is a diagram showing the configuration of another
embodiment of the first embodiment of the discharge circuit
according to the present invention.
[0023] FIG. 4 is a diagram showing the configuration of a
conventional discharge circuit.
PREFERRED EMBODIMENTS OF THE INVENTION
[0024] A simultaneous discharge circuit and a simultaneous battery
discharge method according to an embodiment of the present
invention will be described with reference to the attached
drawings.
[0025] FIG. 1 is a diagram showing the configuration of a discharge
circuit used in a first embodiment of the present invention.
[0026] The discharge circuit used in the fist embodiment of the
present invention has a data processing apparatus 8 comprising a
DC/DC converter 3 controlling a switching element 1 and a switching
element 2 to convert the DC voltage, a battery controller 6
connected to the DC/DC converter 3 and to a battery 4 and a battery
5, and a unit load 7. The battery 4 and the battery 5 supply power
to the data processing apparatus 8. The battery 4 is connected to
the switching element 1 and the battery 5 to the switching element
2.
[0027] The duties of the switching element 1 the switching element
2, which control the ON/OFF state of those switching elements, are
set in the DC/DC converter 3. The duty is defined as a ratio
between the period of time during which a switching element is on
and the period of time during which the switching element is
off.
[0028] In addition, a duty ratio that determines a timing in which
the switching element 1 and the switching element 2 are switched is
also set in the DC/DC converter 3. In other words, the duty ratio
is a ratio between a duty of the switching element 1 connected to
the battery 4 and a duty of the switching element 2 connected to
the battery 5.
[0029] The battery controller 6 checks (i.e., periodically detects)
the capacities of the battery 4 and the battery 5 and, based on the
ratio between the capacity of the battery 4 and that of the battery
5, calculates the duty ratio ensuring an optimum discharge of the
battery 4 and the battery 5. The optimum discharge refers to the
discharge of the battery 4 and the battery 5 such that both
batteries will be exhausted at the same time.
[0030] The calculated duty ratio is input to the DC/DC converter 3
as a duty ratio control signal. The duty ratio entered as the duty
ratio control signal is used to set the duty ratio in the DC/DC
converter 3.
[0031] The duty ratio control signal may be input as an analog
signal or a digital signal.
[0032] Next, the operation of the battery simultaneous discharge
circuit and the battery simultaneous discharge method in the first
embodiment of the present invention will be described with
reference to FIGS. 1 and 2.
[0033] FIG. 2 is a diagram showing the control timing of the
switching element 1 and the switching element 2, which are
controlled by the DC/DC converter 3.
[0034] It is assumed, in the following discussion, that the duty
ratio of the operation of the battery simultaneous discharge
circuit and the battery simultaneous discharge method in the first
embodiment of the present invention is 1:2.
[0035] A period of time starting from period A to period D shown in
FIG. 2 represents a cycle period of the DC/DC converter 3, while a
period of time from period A to period C is a control timing period
of the switching element 1 and the switching element 2. The period
lengths are even.
[0036] Referring to FIG. 1, the battery controller 6 checks
(periodically detects) the capacities of the battery 4 and the
battery 5 and calculates the capacity ratio between the battery 4
and the battery 5. Based on the calculated capacity ratio, the
controller calculates a duty ratio and generates a duty ratio
control signal indicating the duty ratio. The generated duty ratio
control signal is output to the DC/DC converter 3. Then, the DC/DC
converter 3 sets the duty ratio based on the received duty ratio
control signal to control the switching element 1 and the switching
element 2 according to the duty ratio. To control the switching
element 1 and the switching element 2 is to control the ON/OFF
states of the switching element 1 and the switching element 2.
[0037] Next, the control timing of the switching element 1 and the
switching element 2 will be described with reference to FIG. 2.
[0038] The DC/DC converter 3 enables the switching element 1 during
period A and remains ON while the corresponding battery is used for
the power source. The switching element 1 is disabled during
periods B and C and is enabled again by the DC/DC converter 3
during period D. The disabled state, which refers to the state in
which the switching element 1 is not enabled by the DC/DC converter
3, is usually the OFF state.
[0039] On the other hand, the DC/DC converter 3 during period A
disables the switching element 2, unlike the switching element 1.
The DC/DC converter 3 enables it during periods B and C and
maintains ON while the corresponding battery is used for the power
source. The switching element 2 is disabled again during period
D.
[0040] As described above, the switching element 1 and the
switching element 2 repeat the operation, from period A to period
D, under control of the DC/DC converter 3.
[0041] If the battery 4 and the battery 5 are exhausted during
operation and, as a result, the capacity ratio between the battery
4 and the battery 5 changes, the battery controller 6 immediately
calculates the remaining capacity ratio from the remaining
capacities of the battery 4 and the battery 5. The battery
controller calculates a new duty ratio based on the ratio of the
remaining capacities and sends the new duty ratio to the DC/DC
converter 3. In this way, the old duty ratio set in the DC/DC
converter 3 is replaced (undated) by the new duty ratio.
[0042] The DC/DC converter 3 may be of a synchronous rectifier type
converter shown in FIG. 3, a step-up converter (not shown), or a
linear regulator (not shown).
[0043] Although the battery 4 and the battery 5, i.e., two
batteries are used for the battery simultaneous discharge circuit
in this embodiment, three or more batteries may also be used. When
three or more batteries are used, a switching element is connected
to each battery. The duty ratio, which is set in the DC/DC
converter 3 for controlling each of these switching elements, is
determined by the ratio of battery capacities of those three or
more batteries. The capacity ratio may also be used as the duty
ratio.
[0044] The meritorious effects of the present invention are
summarized as follows.
[0045] The discharge circuit and the duty ratio setting method
according to the present invention can perform simultaneous
discharge regardless of the battery voltages, allowing a plurality
of batteries to be exhausted at the same time.
[0046] It should be noted that other objects, features and aspects
of the present invention will become apparent in the entire
disclosure and that modifications may be done without departing the
gist and scope of the present invention as disclosed herein and
claimed as appended herewith.
[0047] Also it should be noted that any combination of the
disclosed and/or claimed elements, matters and/or items might fall
under the modifications aforementioned.
* * * * *