Technical Field
The present invention relates to a power supply apparatus, a power supply method
and a program.
Priority is claimed on Japanese Patent Application No. 2012-224249, filed October 9, 2012,
5 the content of which is incorporated herein by reference.
Background Art
In apparatuses such as a hybrid-type gantry crane, a hybrid car or a hybrid railroad
vehicle, there is a series hybrid apparatus including an engine generator and a power storage
*
10 device. Further, in the gantry crane, there is an apparatus that receives power from an
external power supply of the crane in place of the engine generator (for example, Patent
Literature 1).
In apparatuses which use both power supplied from the engine generator, the
external power supply or the like and discharge power of the power storage device, a
15 maximum value of the power supplied from the power supply can be reduced by using the
discharge power of the power storage device, in addition to the power supplied, in a state in
which a power load is high.
For example, the gantry crane, which receives power supplied from the external
power supply and includes &he power storage device, operates various loads such as a
20 traveling motor or a hoist motor using the power from the external power supply and
charges the power storage device with the power from the external power supply when the
load is low.
On the other hand, when the load is high, for example, when a suspended load is
hoisted, the power storage device performs discharging, and the discharge power from the
25 power storage device is supplied to the load in addition to the power from the external.
power supply. Since a maximum value of the power from the power supply can be
reduced due to the supply o'f the power from the power storage device to the load, it is
possible to lower a power supply voltage.
5 Citation List
Patent Literature
Patent Literature 1
Japanese Unexarnined Patent Application, First Publication No. 2007- 166775
10 Summary of Invention
Technical Problem
When an apparatus such as a crane operates using the power from the power supply
9
and the power from the power storage device, it is necessary to efficiently control charging
and discharging depending on an operation situation of the apparatus. For example, it is
15 necessary to rapidly switch between charging and discharging of the power storage device
and perform charging and discharging without delay.
The present invention provides a power supply apparatus, a power supply method
and a program in which charging and discharging are efficiently controlled for an apparatus
which uses both power supplied and discharge power of a power storage device depending
20 on an operation situation of the apparatus, and power supply is performed.
Solution to Problem
*
A pcwer supply apparatus according to one aspect of the present invention is a
power supply apparatus that supplies power to a power load, the apparatus including: a
25 power conversion device configured to convert alternating current power supplied from a
power supply into direct current power having a first target voltage value to supply the
direct current power to the power load; a power storage device connected in parallel with
the power load to the power conversion device, and capable of charging and discharging; a
charging and discharging control device configured to control charging and discharging so
that a voltage value of the power storage device becomes a second target voltage value; and
5 a target voltage value settink unit configured to compare a state of charge of the power
storage device with a threshold, and increase or decrease at least one of the first target
voltage value and the second target voltage value depending on a comparison result.
Further, a power supply apparatus according to another aspect of the present
invention is the power supply apparatus described above, wherein the power load is capable
10 of generating regenerative power, the threshold is set to be equal to or smaller than a state of
charge obtained by subtracting an accumulated part of the regenerative power fkom a fully
charged state of the power storage device, and when the state of charge of the power storage
device is equal to or greater than the threshold, the target voltage value setting unit increases
or decreases at least one of the first target voltage value and the second target voltage value
*
15 so that the second target voltage value is greater than the first target voltage value.
Further, a power supply apparatus according to another aspect of the present
invention is the power supply apparatus described above, wherein when a state of charge of
the power storage device becomes equal to or smaller than the threshold, the target voltage
value setting unit decreases the second target voltage value to be smaller than the first target
20 voltage value.
Further, a power supply apparatus according to another aspect of the present
invention is the power supply apparatus described above, wherein when a state of charge of
the power storage device becomes equal to or smaller than the threshold, the target voltage
value setting unit increases tbe first target voltage value to be greater than the second target
25 voltage value.
4
Further, a power supply apparatus according to another aspect of the present
invention is the power supply apparatus described above, wherein the power load is a crane
device, and the target voltage value setting unit stops at least one of charging and
discharging of the power storage device when there is no power variation of the power load
5 for a predetermined period of time or more.
Further, a power supply method according to another aspect of the present
invention is a power supply method of a power supply apparatus which includes a power
9
conversion device configured to convert alternating current power supplied from a power
supply into direct current power having a first target voltage value to supply the direct
10 current power to a power load, and a power storage device connected in parallel with the
power load to the power conversion device, and capable of charging and discharging,
wherein the method includes: a charging and discharging control step for controlling
charging and discharging so that a voltage value of the power storage device becomes a
second target voltage value; and a target voltage value setting step for comparing a state of
15 charge of the power storage device with a threshold, and increasing or decreasing at least
one of the first target voltage value and the second target voltage value depending on a
comparison result. 9
Further, a program according to another aspect of the present invention is a
program for causing a computer controlling a power supply apparatus which includes a
20 power conversion device configured to convert alternating current power supplied from a
power supply into direct current power having a first target voltage value to supply the
direct current power to a power load, and a power storage device connected in parallel with
the power load to the power conversion device, and capable of charging and discharging to
execute a charging and discharging control step for controlling charging and discharging so
25 that a voltage value of the power storage device becomes a second target voltage value; and
5
a target voltage value settin. step for comparing a state of charge of the power storage
device with a threshold, and increasing or decreasing at least one of the first target voltage
value and the second target voltage value depending on a comparison result.
5 Advantageous Effects of Invention
According to the power supply apparatus, the power supply method and the
program described above, charging and discharging can be efficiently controlled for an
apparatus which uses both power supplied and discharge power of a power storage device
depending on an operation situation of the apparatus, and power supply can be performed.
10
Brief Description of Drawings
Fig. 1 is a schematic outline view illustrating an outer shape of a tired crane in a
first embodiment of the present invention.
Fig. 2 is a schematic configuration diagram illustrating an apparatus configuration
15 of a power supply apparatus in the embodiment.
Fig. 3 is an illustrative diagram illustrating an example of a target voltage value set
by a programable logic controller in the embodiment.
Fig. 4 is an illustrative diagram illustrating an example of an intermediate voltage
value at the time of a high load in the embodiment.
Fig. 5 is an illustrative diagram illustrating an example of the intermediate voltage
value at the time of regeneration in the embodiment.
Fig. 6 is a flowchart indicating a processing procedure in which a programable
logic controller sets a second target voltage value in the embodiment.
Fig. 7 is a schematic configuration diagram illustrating an apparatus configuration
25 of a power supply apparatus in a second embodiment of the present invention.
Fig. 8 is an illustrative diagram illustrating an example of a target voltage value set
6
by a programable logic controller in the embodiment.
Fig. 9 is a flowchart indicating a processing procedure in which a programable
logic controller sets a first target voltage value in the embodiment. .
5 Description of Embodiments
Hereinafter, the present invention will be described through embodiments of the
invention, but the following embodiments are not intended to limit the invention according
to the claims. Further, not all combinations of characteristics described in the
embodiments are essential to a solution of the invention.
10
Fig. 1 is an outline view illustrating a schematic outer shape of a tired crane
(Rubber Tired Gantry Crane: RTG) in a first embodiment of the present invention.
In Fig. 1, a tired crane system 1 is located on a traveling lane L installed on a road
C
surface R in a container yard Y, rotates tires 6a of a traveling mechanism 6 using a traveling
15 motor, travels by itself on the' traveling lane L, and performs loading and unloading of a
container C.
More specifically, the tired crane system 1 includes a crane body 3 that travels on a
road surface R with the tires 6a, a power supply cable 4 extending from the crane body 3
and connected to a ground power supply facility 2 on the traveling lane L, a cable reel 5
20 provided in the crane body 3 and performing winding and unwinding of the power supply
cable 4, and a box 10 which accommodates the power supply apparatus or a control device
or the like of the crane body 3.
The crane body 3 includes the traveling mechanism 6, a pair of legs 7 that are
C
erected substantially parallel to each other and can be traveled by the traveling mechanism 6,
25 a beam 8 provided in an upper portion between the legs 7, and a suspension mechanism 9
7
suspended from the beam 8.
The pair of legs 7 supports the beam 8 and the suspension mechanism 9, and the
beam 8 supports the suspension mechanism 9 to suspend the suspension mechanism 9.
Also, a guide rail 8a is provided in a longitudinal direction of the beam 8, and the
5 suspension mechanism 9 can travel in the longitudinal direction of the beam 8 along the
guide rail 8a.
More specifically, the suspension mechanism 9 includes a trolley 9a that can travel
along the guide rail 8a of the beam 8, a spreader 9b that grips the container C, a suspension
rope 9c which suspends the spreader 9b from the trolley 9a, and a hoisting machine 9d
10 which performs winding and unwinding of a suspension rope 9c.
With such a configuration, the crane body 3 performs an operation of the loading
and unloading the container C. Specifically, when the spreader 9b grips the container C,
the hoisting machine 9d lifts the container C by hoisting the.suspension rope 9c using the
motive power of the hoist motor. In a state in which the container C is lifted, the
15 suspension mechanism 9 (trolley 9a) travels in a longitudinal direction of the beam 8, and
the crane body travels along the traveling lane L to move the container C. When the
container C moves to a target position, the hoisting machine 9d lowers the container C by
unwinding the suspension rope 9c.
Here, the crane body 3 performs various operations such as traveling the crane
20 body 3, travelling the suspension mechanism 9, and hoisting the suspension rope 9c by the
hoisting machine 9d using both the power from the ground power supply facility 2 and the
power from the power storage device included in the power supply apparatus
accommodated in the box 10.
Specifically, a cable side connector 4a is provided on an end of the power supply
25 cable 4 and connected with a power supply side connector 2a of the ground power supply
8
facility 2. The crane body 3 receives power from the ground power supply facility 2
through the power supply cable 4, and supplies power to each part of the crane body 3
through the power supply apparatus accommodated in the box 10. Further, the power
supply apparatus controls charging and discharging of the power storage device, and
5 supplies discharge power of the power storage device to all parts of the crane body 3 in
addition to the power from the ground power supply facility 2, as will be described below.
The cable reel 5 performs winding an excess portion of the power supply cable 4 so
that the power supply cable 4 is not loose and traveling the crane body 3 is not hindered.
Next, a configuration of the power supply apparatus will be described with
10 reference to Fig. 2.
Fig. 2 is a schematic configuration diagram illustrating an apparatus configuration
of the power supply apparatus 100. In Fig. 2, the power supply apparatus 100 includes an
ACIDC converter 101, a power storage device 11 1, a charging and discharging control
device 112, and a programable logic controller 121. Further, the ground power supply
15 facility 2, the power supply cable 4 which connects the ground power supply facility 2 and
the power supply apparatus 100, and a load 90 to which the power supply apparatus .I00
supplies power are illustrated in Fig. 2.
The ground power supply facility 2 includes the power supply side connector 2% a
power supply wit 2b, and a tkansformer 2c, and transforms alternating current power output
20 by the power supply unit 2b using the transformer 2c, and outputs the resultant power from
the power supply side connector 2a. As described above, the cable side connector 4a is
connected to the power supply side connector 2a, and the power supply cable 4 supplies the
alternating current power received fiom the ground power supply facility 2 via the cable
side connector 4a to the power supply apparatus 100.
2 5 Further, the ground power supply facility 2 corresponds to an example of the power
supply in this embodiment. The power supply unit 2b may be a power generation facility
or may be a power reception facility that receives, for example, a commercial supply power.
4
Further, the power supply in this embodiment is not limited to an external power supply (a
power supply provided outside the power supply apparatus), such as the ground power
5 supply facility 2. For example, the power supply apparatus 100 may include a power
supply inside the power supply apparatus 100. For example, the power supply apparatus
100 may include a generator.
The load 90 is a generic name for a power load in the crane body 3, such as a
traveling motor that rotates the tires 6a (Fig. 1) to travel the crane body 3, a hoist motor that
10 is a motive power source when the hoisting machine 9d hoists the suspension rope 9c, or a
control device of the crane body 3.
Particularly, the load 90 can generate regenerative power. Specifically, the
traveling mechanism 6 operates the traveling motor as a regeneration brake at the time of
braking the crane body 3, and performs the regeneration. Further, when unwinding the
15 suspension rope 9c and lowering the suspended load, the hoisting machine 9d performs the
regeneration while operating .the hoist motor as the regeneration brake and to adjust a
lowering speed of the suspended load.
The ACIDC converter 10 1 converts the alternating current power supplied from the.
ground power supply facility 2 into direct current power having a first target voltage value
20 and supplies the direct current power to the load 90. In this embodiment, the first target
voltage value is set as a fixed voltage value in advance.
The power storage 'device 11 1 performs charging and discharging, for example,
with a rechargeable battery such as a lead battery or a lithium ion battery. Here, the power
storage device 11 1 is connected in parallel with the load 90 to the ACIDC converter 101
25 through the charging and discharging control device 112. With such a connection
10
relationship, the power storage device 11 1 is charged in a floating manner with the power
from the ACIDC converter 101 when a voltage value of the power from the ACIDC
converter 101 is higher than a voltage value of the power storage device 11 1. On the other
hand, the power storage device 11 1 performs discharging and supplies the power to the load
5 90 when the voltage value of the power from the ACIDC converter 101 is lower than the
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voltage value of the power storage device 1 1 1.
Further, the power storage device 11 1 includes a BMU (Battery Management Unit)
to measure the state of charge of the rechargeable battery and output the state of charge to
the programable logic controller 12 1.
The charging and discharging control device 112 controls charging and discharging
of the power storage device 11 1 so that the voltage of the power storage device 111
becomes a second target voltage value. In this embodiment, the second target voltage
value is a variable voltage value set by the programable logic controller 12 1.
The programable logic controller 121 compares the state of charge of the
15 rechargeable battery of the power storage device 111 (hereinafter referred simply to as a
"state of charge of the power storage device 111") with a threshold, and increases or
decreases the second target voltage value depending on a comparison result. Here, the
programable logic controller 121 stores a discharging threshold ShA at which the power
storage device 111 is switched fiom charging to discharging and a charging threshold ShB
20 at which the power storage device 11 1 is switched from discharging to charging, in advance.
Among these, the discharging threshold ShA corresponds to an example of a threshold in
this embodiment. Further, the programable logic controller 121 corresponds to an example
of a target voltage value setting unit in this embodiment.
The discharging threshold ShA is set to be equal to or smaller than a state of charge
*
25 obtained by subtracting an accumulated part of the regenerative power from a state of full
charge of the power storage device 111. For example, generation scenarios of the
regenerative power to be stored in the power storage device 11 1 are assumed to be braking
the crane body 3 when the crane body 3 arrives at a position of the container, braking the
crane body 3 when the crane body 3 arrives at a container lowering position, and braking
5 the hoisting machine when the container is lowered. In this case, total regenerative power
expected to be generated by two brakings of the crane body 3 and one lowering of the
container corresponds to an accumulated part of the regenerative power.
A manager of the tired crane system 1 calculates a state of charge obtained by
subtracting the accumulated part of the regenerative power from the fully charged state, that
10 is, a state of charge obtained in consideration of a margin for storage of the regenerative
power. Also, the manager of the tired crane system 1 stores the calculated state of charge
in the programable logic controller 121 as the discharging threshold ShA in advance.
Alternatively, the manager of the tired crane system 1 may store a state of charge obtained
by further subtracting a margin obtained in consideration of battery deterioration or the like
15 from the calculated state of charge in the prograrnable logic controller 121 as the
discharging threshold ShA in advance.
On the other hand, the charging threshold ShB is set to a value smaller than the
*
discharging threshold ShA. Further, if the charging threshold ShB < the discharging
threshold ShA, the power supply apparatus 100 (the prograrnable logic controller 121 and
20 the charging and discharging control device 112) can control the power storage device 11 1.
However, it is preferable for a dead zone (hysteresis) to be provided between the charging
threshold ShB and the discharging threshold ShA so as to prevent frequent occurrence of
switching between charging and discharging.
When the state of charge of the power storage device 111 becomes equal to or
25 greater than the discharging threshold ShA, the power supply apparatus 100 increases the
12
second target voltage value tQ be greater than the first target voltage value. According to
this target voltage value setting, the charging and discharging control device 112 causes the
power storage device 11 1 to perform discharging. On the other hand, if the state of charge
of the power storage device 11 1 become smaller than the charging threshold ShB, the power
5 supply apparatus 100 decreases the second target voltage value to be smaller than the first
target voltage value. According to this target voltage value setting, the charging and
discharging control device 11 2 causes the power storage device 1 11 to perform charging. ,
Fig. 3 is an illustrative diagram illustrating an example of the target voltage value
set by the programable logic controller 12 1. h Fig. 3, a line L 1 1 1 indicates an example of
10 a state of charge (SOC) of the power storage device 11 1. Further, a line L12 1 indicates an
example of a second targetzvoltage value set by the programable logic controller 121.
Further, a line L122 indicates an example of an intermediate voltage value between the
AC/DC converter 1 0 1 and the charging and discharging control device 1 12.
In a state before time T11, the state of charge of the power storage device 11 1 is
15 smaller than discharging threshold ShA. Therefore, the programable logic controller 12 1
sets the target voltage value (second target voltage value) of the power storage device 11 1 to
a voltage value VdsetO smaller than a voltage value Vpset which is an output voltage target'
value (first target voltage value) of the ACIDC converter 10 1. Based on this voltage target
value setting, the charging and discharging control device 112 controls the power storage
20 device 11 1 so that the voltage value of the power storage device 11 1 becomes the voltage
z
value VdsetO. . Accordingly, the voltage of the ACIDC converter 10 1 becomes higher than
the voltage of the power storage device 111, and float charging is performed from the
ACIDC converter 10 1 to the power storage device 11 1.
The state of charge of the power storage device 111 increases due to the float
25 charging, and the state of charge reaches the discharging threshold ShA at time T11. Then,
13
the programable logic controller 121 sets the target voltage. value (second target voltage
value) of the power storage device 111 to a voltage value Vdsetl higher than the voltage
value Vpset which is the output voltage target value (first target voltage value) of the
ACJDC converter 101. Based on this voltage target value setting, the charging and
5 discharging control device 112 controls the power storage device 11 1 so that the voltage
value of the power storage device 11 1 becomes the voltage value Vdsetl . Accordingly, the
voltage of the power storage device 111 becomes higher than the voltage of the ACJDC
converter 10 1, and the power storage device 1 1 1 performs discharging to the load 90.
The state of charge of the power storage device 111 decreases due to the
10 discharging, and the state of charge reaches the charging threshold ShB at time T12. Then,
the programable logic controller 121 returns the target voltage value (second target voltage
value) of the power storage device 111 to the voltage value VdsetO. Accordingly, the
voltage of the ACIDC converter 101 becomes higher than the voltage of the power storage
device 11 1, and float chargi& is performed from the ACJDC converter 101 to the power
15 storage device 11 1, similarly to the state before time TI 1.
Further, in the example of Fig. 3, the power load of the load 90 is small, and an
influence of the voltage decrease is small. Therefore, the intermediate voltage value
indicated by the line L122 becomes a value between the first target voltage value and the
second target voltage value.
Next, discharging during a high load will be described with reference to Fig. 4.
Fig. 4 is an illustrative diagram illustrating an example of an intermediate voltage
value during a high load. In Fig. 4, a line L211 indicates an example of a second target
voltage value set by the programable logic controller 121. In the example of Fig. 4, the
9
programable logic controller 121 continues setting the second target voltage value to a
25 voltage value VdsetO smaller than a first target voltage value.
14
Further, a line L212 indicates an example of the intermediate voltage value
between the ACIDC converter 101 and the charging and discharging control device 112.
Before time T21, a power load of the load 90 is low. Accordingly, float charging
is performed from the ACIDC converter 101 to the power storage device 11 1, similarly to
5 the state before time Tl 1 of Fig. 3.
On the other hand, during time T21 to time T22, the power load of the load 90 is
high. Therefore, a voltage 'decrease occurs, and the intermediate voltage value indicated
by the line L212 becomes smaller than the second target voltage value indicated by the line
L2 1 1. Accordingly, the voltage of the power storage device 11 1 is higher than a voltage of
10 the connection destination (particularly, the load 90), and the power storage device 111
perfo,rrns discharging to the load 90.
Thus, when the power load of the load 90 is high, the power storage device 111
performs discharging to the load 90 even in a state in which the programable logic
controller 121 sets the second target voltage value to the voltage value smaller than the first
15 target voltage value. Accordingly, a maximum value of the power supplied from the
ground power supply facility 2 can be reduced and the power supply voltage can be lowered.
C
Therefore, it is.possible to relatively reduce the voltage value output by the transformer 2c
(Fig. 2).
Further, the power storage device 11 1 can store the regenerative power even in a
20 state in which the second target voltage value is greater than the first target voltage value.
Fig. 5 is an illustrative diagram illustrating an example of the intermediate voltage
value at the time of regeneration. In Fig. 5, a line L3 11 indicates an example of the second
target voltage value set by the programable logic controller 121. In the example of Fig. 5,
the programable logic controller 121 continues setting the second target voltage value to the
25 voltage value Vdsetl greater than the first target voltage value.
15
Further, a line L312 indicates an example of the intermediate voltage value
between the ACIDC converter 10 1 and the charging and discharging control device 11 2.
Before time T3 1, the load 90 does not perform regeneration, and the power storage
device 11 1 performs discharging to the load 90, similarly to the state from time TI1 to time
5 T12inFig.3.
On the other hand, in time T3 1 to time T32, the load 90 performs the regeneration,
the intermediate voltage value indicated by the line L3 12 increases due to the regenerative
power, and the intermediate voltage value becomes higher than the second target voltage
value indicated by the line L3 11. Accordingly, the voltage of the power storage device 11 1
4
10 is lower t h a ~th e voltage of a connection destination (particularly, the load 90), and the
power storage device 1 11 stores the regenerative power.
Thus, when the load 90 performs the regeneration, the power storage device 111
stores the regenerative power even in a state in which the programable logic controller 121
sets the second target voltage value to the voltage value greater than the first target voltage
15 value. In light of the fact that the regenerative power can be stored instead of being
discarded in this way, the power supply apparatus 100 can efficiently control charging and
discharging of the power storage device 111 depending on the operation situation of the
crane body 3 and perform the power supply to the load 90.
Further, as described above, the charging and discharging control device 112
C
20 controls charging and discharging of the power storage device 11 1 in consideration of a
margin for storage of the regenerative power, and thus, overcharging does not occur even
when the power storage device 11 1 stores the regenerative power.
Next, an operation of the power supply apparatus 100 will be described with
reference to Fig. 6.
25 Fig. 6 is a flowchart illustrating a processing procedure in which the programable
16
logic controller 121 sets the second target voltage value. When power is supplied to the
programable logic controller 121 (ON), the programable logic controller 121 enters an
operating state and performs the process of Fig. 6
In the process of Fig. 6, first, the programable logic controller 121 initially sets the
5 second target voltage value to the voltage value VdsetO smaller than the first target voltage
value (step S101). In a state in which the second target voltage value is the voltage value
VdsetO, as described above, the power storage device 11 1 performs charging, but when the
load 90 is high, the power storage device 11 1 performs discharging to the load 90.
Then, the programable logic controller 121 determines whether the state of charge
10 of the power storage device 111 is equal to or greater than the discharging threshold ShA
(step S102). When it is determined that the state of charge is smaller than the discharging
threshold ShA (step S102: No), the process returns to step S102. That is, the programable
C
logic controllzr 12 1 waits for the state of charge of the power storage device 11 1 to be equal
to or greater than the discharging threshold ShA.
15 On the other hand, when it is determined in step S 102 that the state of charge of the
power storage device 111 is equal to or greater than the discharging threshold ShA (step
S102: YES), the programable logic controller 121 sets the second target voltage value to the
voltage value Vdsetl greater than the first target voltage value (step S103). In a state in
which the second target voltage value becomes the voltage value Vdsetl, as described
20 above, the power storage device 11 1 performs the discharging to the load 90, but when the
load 90 performs the regeneration, the power storage device 11 1 stores the regenerative
power.
Then, the programable logic controller 12 1 determines whether the state of charge
of the power storage device 11 1 is equal to or smaller than the charging threshold ShI3 (step
25 S104). When it is determined that the state of charge is higher than the charging threshold
17
Shl3 (step S104: NO), the process returns to step S104. That is, the programable logic
controller 121 waits for the state of charge of the power storage device 11 1 to be equal to or:
smaller than the charging threshold ShB.
On the other hand, when it is determined in step S104 that the state of charge of the
5 power storage device 11 1 is equal to or smaller than the charging threshold ShB (step S 104:
*
YES), the programable logic controller 121 sets the second target voltage value to the
voltage value VdsetO (step S 105).
Then, the process returns to step S 102.
As described above, the charging and discharging control device 112 switches
10 between charging and discharging of the power storage device 11 1 by changing the voltage
of the power storage device 111 depending on the second target voltage value set by the
programable logic controller 121. Accordingly, since it is not necessary to switch the
charging and discharging of the power storage device 111 using a switch, a sudden
interruption does not occur. That is, a delay of start of the power supply from the power
15 storage device 11 1 due to a switch switching operation and a delay of start of charging of
*
the power storage device 11 1 do not occur. In this regard, the power supply apparatus 100
can efficiently control charging and discharging of the power storage device 11 1 depending
on the operation situation of the crane body 3, and can perform the power supply to the load
90.
Further, when the power load of the load 90 is high, the power storage device 11 1
performs discharging to the load 90 even in a state in which the programable logic
controller 121 sets the second target voltage value to the voltage value smaller than the first
target voltage value. Accordingly, the maximum value of the power supplied from the
ground power supply facility 2 can be reduced and the power supply voltage can be lowered.
25 Therefore, it is possible to rdatively reduce the voltage value output by the transformer 2c
18
(Fig. 2).
Further, when the load 90 performs the regeneration, the power storage device 11 1
stores the regenerative power even in a state in which the programable logic controller 121
sets the second target voltage value to the voltage value greater than the first target voltage
5 value. In light of the fact that the regenerative power can be stored instead of being
discarded in this way, the power supply apparatus 100 can efficiently control charging and
discharging of the power storage device 111 depending on the operation situation of the
crane body 3 and perform the power supply to the load 90.
Z
FunI-16r, since the charging and discharging control device 112 controls charging
10 and discharging of the power storage device 11 1 in consideration of a margin for storage of
the regenerative power, overcharging does not occur even when the power storage device
11 1 stores the regenerative power.
Further, since the programable logic controller 121 can control charging and
discharging of the power storage device 11 1 by setting the target voltage value by referring
15 to only the state of charge of the power storage device 11 1, it is possible to control charging
and discharging of the power storage device 11 1 using a simple configuration.
Further, in the power supply apparatus 100, it is possible to control charging and
discharging of the power storage device 11 1 even when the ACIDC converter 101 does not
have an output voltage setting value switching function.
Further, in the power supply apparatus 100, the charging and discharging control
device 11 2 performs the switching between the voltage setting values. Accordingly, the
following effects are obtained in comparison with a case in which the ACIDC converter 101
performs the switching between the voltage setting values.
That is, it is not necessary to add an output voltage setting value switching hction
25 to the ACIDC converter when the charging and discharging control device and the power
19
storage device are additionally provided in an electric reel type gantry crane that does not
C
include a power storage device with an ACIDC converter. In this regard, additional work
can be decreased.
Further, the case in which this embodiment is applied to the gantry crane has been
5 described above, but an application scope of the present invention is not limited thereto.
For example, the present invention can be applied to varicus apparatuses which use both
power from the power supply and power from the power storage device, such as a series
hybrid car or a series hybrid railroad vehicle. The same applies to a second embodiment to
be described below.
Further, the programable logic controller 121 may change the target voltage value
based on the operation situation of the crane body 3. For example, when there is no power
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variation of the load 90 (in either the winding operation or the traveling operation) within a
set time, the charging and discharging control device 112 may stop at least one of the
charging or the discharging of the power storage device 11 1 according to an instruction of
1 5 the programable logic controller 12 1. Also, when the load power variation is detected, the
charging and discharging control device 112 may restore the power storage device 11 1 to an
original state.
Accordingly, it is possible to prevent repetition of ,an unnecessary charging and
discharging operation when there is no load power variation (in either a winding operation
20 or a traveling operation). The same applies to a second embodiment to be described next.
C
While the case in which the programable logic controller 121 changes the second
target voltage value has been described above, the programable logic controller 121 may
change the first target voltage value rather than the second target voltage value.
25 Hereinafter, this will be described.
20
Fig. 7 is a schematic configuration diagram illustrating an apparatus configuration
of a power supply apparatus in the second embodiment of the present invention. Ln Fig. 7,
the power supply apparatus 200 includes an ACIDC converter 201, a power storage device
11 1, a charging and discharging control device 2 12, and a programable logic controller 22 1.
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5 Further, a ground power supply facility 2, a power supply cable 4 which connects the
ground power supply facility 2 and the power supply apparatus 100, and a load 90 to which
the power supply apparatus 100 supplies power are illustrated in Fig. 7. In Fig. 7, units
having the same functions corresponding to all the units of Fig. 2 are denoted with the same
reference signs (2,2a, 2b, 2c, 4,4% 5, 90, and 11 1) and description thereof will be omitted.
Further, an external form of the tired crane in the second embodiment is the same
as that described with reference to Fig. 1 in the first embodiment, and illustration and
description thereof will be omitted.
A tired crane system lb is different from the tired crane system 1 (Fig. 2) in that the
programable logic controlle; 221 changes the first target voltage value rather than the
15 second target voltage value.
When a state of charge of the power storage device 11 1 becomes equal to or greater
than the discharging threshold ShA, the programable logic controller 221 increases the first
target voltage value to be greater than the second target voltage value.
The ACIDC converter 201 changes an output voltage value of the ACIDC converter
20 201 depending on the first target voltage value set by the programable logic controller 22 1.
The charging and discharging control device 212 controls charging and discharging
of the power storage device 11 1 by controlling the voltage value of the power storage device
11 1 based on the second target voltage value, similarly to the charging and discharging
control device 112. Howevkr, the charging and discharging control device 2 12 is different
25 from the charging and discharging control device 112 in that the second target value is a
2 1
fixed value.
Fig. 8 is an illustrative diagram illustrating an exanple of the target voltage value
set by the programable logic controller 221. In Fig. 8, a line L411 indicates an example of
a state of charge (SOC) of the power storage device 11 1. Further, a line L42 1 indicates ari
5 example of a first target voltage value set by the programable logic controller 22 1.
In a state before time T41, the state of charge of the power storage device 111 is
smaller than the discharging threshold SM. Therefore, the programable logic controller
'+
221 sets the output voltage target value (first target voltage value) of the ACIDC converter
201 to a voltage value Vpsetl greater than a voltage value Vdset which is a target voltage
10 value (second target voltage value) of the power storage device 11 1. Based on this voltage
target value setting, the ACDC converter 201 controls the ACDC converter 201 so that its
output voltage value becomes the voltage value Vpsetl. Accordingly, the voltage of the
ACIDC converter 201 becomes higher than the voltage of the power storage device 11 1, and
float charging is performed from the ACIDC converter 201 to the power storage device 11 1.
15 The state of charge of the power storage device 111 increases due to the float
charging, and the state of charge reaches the discharging threshold ShA at time T41. Then,
the programable logic contr~ller2 21 sets the output voltage target value (the first target
voltage value) of the ACIDC converter 201 to a voltage value VpsetO smaller than the
voltage value Vdset which is the target voltage value (second target voltage value) of the
20 power storage device 11 1. Based on this voltage target value setting, the AC/DC converter
201 controls the ACIDC converter 201 so that the output voltage value becomes the voltage
value VpsetO. Accordingly, the voltage of the power storage device 11 1 becomes higher
than the voltage of the ACIDC converter 201, and the power storage device 11 1 performs.
discharging to the load 90.
2 5 The state of charge of the power storage device 111 decreases due to discharging,
and the state of charge reaches the charging threshold ShB at time T42. Then, the
prograrnable logic controller 221 returns the output voltage target value (first target voltage
value) of the AC/DC converter 201 to the voltage value Vpsetl. Accordingly, the voltage
of the ACIDC converter 201 becomes higher than the voltage of the power storage device
5 1 1 1, and float charging is performed from the AC/DC converter 201 to the power storage
device 1 1 1, similarly to the state before time T41.
Thus, the power supply apparatus 200 can switch between charging and
discharging of the power storage device 111, similarly to the case of the power supply
apparatus 1 00.
Even during a high bad of the load 90, when the power load of the load 90 is high,
the power storage device 11 1 performs discharging to the load 90 even in a state in which
the programable logic controller 221 sets the first target voltage value to a voltage value
higher than the second target voltage value, similarly to the description with reference to Fig.
4. Accordingly, the maximum value of the power supplied from the ground power supply
15 facility 2 can be reduced, and the power supply voltage can be lowered. Therefore, it is
possible to relatively reduce the voltage value output by the transformer 2c (Fig. 2).
Further, even in the regeneration of the load 90, the power storage device 111
stores the regenerative power when the load 90 performs the regeneration even in a state in
which the programable logic controller 221 sets the first target voltage value to the voltage
20 value smaller than the se&nd target voltage value, similarly to the description with
reference to Fig. 5. In light of the fact that the regenerative power can be stored instead of
being discarded in this way, the power supply apparatus 200 can efficiently control charging
and discharging of the power storage device 11 1 depending on the operation situation of the
crane body 3b and perform the power supply to the load 90.
2 5 Further, the charging and discharging control device 212 controls charging and
23
discharging of the power storage device 11 1 in consideration of a margin for storage of the
regenerative power, similarly to the case of the charging and discharging control device 112.
Therefore, overcharging does not occur even when the power storage device 11 1 stores the
regenerative power.
5 Next, an operation of the power supply apparatus 200 will be described with
reference to Fig. 9.
Fig. 9 is a flowchart illustrating a processing procedure in which the programable
logic controller 221 sets the first target voltage value. When power is supplied to the
programable logic controller 221, programable logic controller 221 becomes an operating
10 state and performs the process of Fig. 9.
In the process of Fig. 9, first, the programable logic controller 221 initially sets the
first target voltage value to a voltage value Vpsetl higher than the second target voltage
value (step S201). In a stzte in which the first target voltage value becomes a voltage
value Vpsetl, as described above, the power storage device 11 1 performs charging, but
15 when the load 90 is high, the power storage device 11 1 performs discharging to the load 90.
Then, the programable logic controller 221 determines whether the state of charge
of the power storage device 111 is equal to or greater than the discharging threshold ShA
(step S202). When it is determined that the state of charge is smaller than the discharging
threshold ShA (step S202: NO), the process returns to step S202. That is, the programable
20 logic controller 22 1 waits for the state of charge of the power storage device 11 1 to be equal
to or greater than the discharging threshold ShA.
On the other hand, when it is determined in step S202 that state of charge of the
%
power storage device 111 is equal to or greater than the discharging threshold ShA (step
S202: YES), the programable logic controller 221 sets the first target voltage value to the
25 voltage value VpsetO smaller than the second target voltage value (step S203). In a state in
24
which the second target voltage value becomes the voltage value VpsetO, as described
above, the power storage device 11 1 performs discharging to the load 90, but when the load
90 performs the regeneration, the power storage device 111 performs charging with the
regenerative power.
5 Then, the programable logic controller 221 determines whether the state of charge
of the power storage device 11 1 is equal to or smaller than the charging threshold ShB (step
S204). When it is determined that the state of charge is higher than the charging threshold
ShB (step S204: No), the process returns to step S204. That is, the programable logic
controller 221 waits for the state of charge of the power storage device 11 1 to be equal to or
10 smaller than the charging threshold ShI3.
On the other hand, when it is determined in step S204 that state of charge of the
power storage device 11 1 is equal to or smaller than the charging threshold ShB (step S204:
YES), the prograrnable logic controller 221 sets the first target voltage value to the voltage
value Vpsetl (step S205).
15 Then, the process returns to step S202.
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As described above, the ACIDC converter 201 switches between charging and
discharging of the power storage device 111 by changing the output voltage value of the
ACIDC converter 201 depending on the fust target voltage value set by the programable
logic controller 221. Accordingly, since it is not necessary to switch between charging and
20 discharging of the power storage device 11 1 using a switch, a sudden interruption does not
occur. That is, a delay of start of the power supply from the power storage device 11 1 due
to the switch switching operation or a delay of the charge start of the power storage device
111 does not occur. In this regard, the power supply apparatus 200 can efficiently control
charging and discharging of the power storage device 11 1 depending on the operation
25 situation of the crane body 3b, and perform power supply to the load 90.
Further, when a power load of the load 90 is high, the power storage device 11 1
performs discharging to the load 90 even in a state in which the programable logic
controller 221 sets the first target voltage value to the voltage value higher than the second
target voltage value. Accordingly, the maximum value of the power supplied from the
5 ground power supply facility 2 can be reduced, and the power supply voltage can be
lowered. Therefore, it is possible to relatively reduce the voltage value output by the
transformer 2c (Fig. 2).
Further, when the load 90 performs the regeneration, the power storage device 11 1
stores the regenerative powe? even in a state in which the programable logic controller 221
10 sets the first target voltage value to the voltage value smaller than the second target voltage
value. In light of the fact that the regenerative power can be stored instead of being
discarded in this way, the power supply apparatus 200 can efficiently control charging and
discharging of the power storage device 111 depending on the operation situation of the
crane body 3b and perform the power supply to the load 90.
15 Further, the charging and discharging control device 212 controls charging and
discharging of the power storage device 11 1 in consideration of a margin for storage of the
regenerative power, and thus, overcharging does not occur even when the power storage
device 11 1 stores the regenerative power.
9
Furcheir, since the programable logic controller 221 can control charging and
20 discharging of the power storage device 11 1 by setting the target voltage value by referring
to only the state of charge of the power storage device 11 1, it is possible to control charging
and discharging of the power storage device 11 1 using a simple configuration.
Further, the power supply apparatus 200 can control charging and discharging of
the power storage device 11 1 even when the charging and discharging control device 212
25 does not have a voltage instruction switching function.
26
Further, the process of each unit may be performed by recording a program for
realizing all or some of the hctions of the charging and discharging control device 112 or
'+
2 12 or the programable logic controller 121 or 221 in a computer-readable recording
medium, loading the program recorded in the recording medium to a computer system, and
5 executing the program. Further, "the computer system" referred to herein includes an OS
or hardware such as a peripheral device.
Further, the "computer system" includes a homepage providing environment (or
display environment) if a WWW system is being used.
Further, the "computer-readable recording medium'" refers to a portable medium
10 such as a flexible disk, a magnetic optical disc, a ROM, or a CD-ROM, or a storage device
such as a hard disk embedded in the computer system. Further, the "computer-readable
recording medium" also incl~tdesa recording medium that dynamically holds a program for
a short period of time, such as a communication line when the program is transmitted over a
network such as the Internet or a communication line such as a telephone line or a recording
15 medium that holds a program for a certain period of time, such as a volatile memory inside
a computer system including a server and a client in such a case. Further, the program
may be a program for realizing some of the above-described functions or may be a program
capable of realizing the above-described functions in a combination with a program
previously stored in the computer system.
While the embodiments of the present invention have been described in detail with
reference to the drawings, a specific configuration is not limited to the embodiments, and,
C
for example, a.design change that does not depart from the gist of the present invention is
included in the specific configuration.
Industrial Applicability
The present invention relates to a power supply apparatus that supplies power to a
power load, the apparatus including: a power conversion device configured to convert
5 alternating current power supplied from a power supply into direct current power having a
Z
first target voltage value to supply the direct current power to the power load; a power
storage device connected in parallel with the power load to the power conversion device,
and capable of charging and discharging; a charging and discharging control device
configured to control charging and discharging so that a voltage value of the power storage
10 device becomes a second target voltage value; and a target voltage value setting unit
configured to compare a state of charge of the power storage device with a threshold, and
increase or decrease at least one of the first target voltage value and the second target
voltage value depending on a comparison result.
According to the present invention, it is possible to efficiently control charging and
15 discharging depending on an operation situation of a device which uses both the power
Z
supplied and discharge power of the power storage device with respect to the device, and
perform power supply.
WE CLAIM:
1. A power supply apparatus that supplies power to a power load, the apparatus
comprising:
a power conversion device configured to convert alternating current power
supplied from a power supply into direct current power having a first target voltage
value to supply the direct current power to the power load;
a power storage device connected in parallel with the power load to the
4
power conversion device, and capable of charging and discharging;
a charging and discharging control device configured to control charging
and discharging so that a voltage value of the power storage device becomes a second
target voltage value; and
a target voltage value setting unit configured to compare a state of charge
of the power storage device with a threshold, and increase or decrease at least one of
the first target voltage value and the second target voltage value depending on a
comparison result.
2. The power supply apparatus according to claim 1,
4
wherein the power load is capable of generating regenerative power,
the threshold is set to be equal to or smaller than a state of charge obtained
by subtracting an accumulated part of the regenerative power from a fully charged
state of the power storage device, and
when the state of charge of the power storage device is equal to or greater
than the threshold, the target voltage value setting unit increases or decreases at least
one of the first target voltage value and the second target voltage value so that the
second target voltage value is greater than the first target voltage value.
29
3. The power supply apparatus according to claim 1,
wherein when a state of charge of the power storage device becomes equal
to or greater than the threshold, the target voltage value setting unit increases the
second target voltage value to be greater than the first target voltage value.
4. The power supply apparatus according to claim 1,
wherein when a state of charge of the power storage device becomes equal.
to or greater than the threshold, the target voltage value setting unit decreases the first
target voltage value to be smaller than the second target voltage value.
5. The power supply apparatus according to claim 1,
wherein the power load is a crane device, and
the target voltage value setting unit stops at least one of charging and
discharging of the power storage device when there is no power variation of the
power load for a predetermined period of time or more.
6. A power supply method of a power supply apparatus which includes
a power conversion device configured to convert alternating current power
supplied from a power supply into direct current power having a first target voltage
value to supply the direct current power to a power load, and
a power storage device connected in parallel with the power load to the
power cdnversion device, and capable of charging and discharging,
wherein the method comprising:
a charging and discharging control step for controlling charging and
discharging so that a voltage value of the power storage device becomes a second
target voltage value; and
30
a target voltage value setting step for comparing a state of charge of the
power storage device with a threshold, and increasing or decreasing at least one of
the first target voltage value and the second target voltage value depending on a
comparison result.
7. A program for causing a computer controlling a power supply apparatus which
includes
a power conversion device configured to convert alternating current power
supplied fi-om a power supply into direct current power having a first target voltage
value to supply the direct current power to a power load, and
a power storage device connected in parallel with the power load to the
power conversion device, and capable of charging and discharging,
to execute:
a charging,and discharging control step for controlling charging and
discharging so that a voltage value of the power storage device becomes a second
target voltage value; and
a target voltage value setting step for comparing a state of charge of the
power storage device with a threshold, and increasing or decreasing at least one of
the first target voltage value and the second target voltage value depending on a
comparison result.