FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
POWER SUPPLY;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION
ORGANISED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE
ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO
1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED
2
DESCRIPTION
Field
[0001] The present disclosure relates to a power supply
5 that supplies direct-current power to a load to be
installed on a railway vehicle.
Background
[0002] A storage battery is among loads that are
10 installed on railway vehicles and supplied with directcurrent power. A power supply described in Patent
Literature 1, which is mentioned below, includes a power
converter apparatus that charges a storage battery
installed on a railway vehicle.
15 [0003] Generally, appropriate switching based on
charging voltage for the storage battery is performed
between a current-limiting mode and a constant-voltage mode
in charging the storage battery. Furthermore, during the
charging of the storage battery, conduction ratio control
20 is performed to control a length of application of a gate
signal to a gate of a switching element included in a power
converter.
Citation List
25 Patent Literature
[0004] Patent Literature 1: Japanese Patent Application
Laid-open No. S62-217802
Summary of Invention
30 Problem to be solved by the Invention
[0005] A unique problem with a power supply installed on
a railway vehicle is significant fluctuation of overhead
line voltage that is applied, as a base of input voltage
3
for the power supply, from an overhead line, a third rail,
or the like. Therefore, when there is, for instance, a
sudden increase in overhead line voltage, a conduction
ratio is reduced by the conduction ratio control for
5 restrained fluctuation of input voltage for the storage
battery under charge control. However, there are cases
where the fluctuation of the overhead line voltage cannot
be followed, leading to an increase in charging current for
the storage battery that causes a switchover from the
10 constant-voltage mode to the current-limiting mode. The
switchover from the constant-voltage mode to the currentlimiting mode, on the other hand, causes a sharp step-up in
the conduction ratio of the gate signal that may lead to
problematic occurrence of excessive inrush current into the
15 storage battery.
[0006] The present disclosure has been made in view of
the above, and an object of the present disclosure is to
obtain a power supply capable of preventing excessive
inrush current from flowing into a storage battery even
20 upon a switchover from the constant-voltage mode to the
current-limiting mode.
Means to Solve the Problem
[0007] To solve the above-stated problem and achieve the
25 object, a power supply according to the present disclosure
is a power supply equipped with a power converter that
supplies direct-current power to a load to be installed on
a railway vehicle while charging a storage battery as one
of a plurality of the loads. The power supply includes a
30 voltage sensor, a current sensor, and a controller. The
voltage sensor detects direct-current voltage that the
power converter applies to the storage battery. The
current sensor detects current flowing between the power
4
converter and the storage battery. The controller controls
the storage battery charging on the basis of a detection
value of the voltage sensor and a detection value of the
current sensor. The power supply has operating modes
5 including a constant-voltage mode where the storage battery
is charged at a constant voltage and a current-limiting
mode where the storage battery is charged with an upper
limit specified for charging current for the storage
battery. The controller includes a first control block
10 that controls the constant-voltage mode, a second control
block that controls the current-limiting mode, and a
conduction ratio command computer. The conduction ratio
command computer computes a conduction ratio command based
on an output of either the first control block or the
15 second control block. The conduction ratio command is a
value commanding a conduction ratio of a gate signal that
operates a switching element included in the power
converter. The second control block includes a primary lag
block that allows a signal to go through for input to the
20 conduction ratio command computer upon an operating mode
switchover from the constant-voltage mode to the currentlimiting mode.
Effect of the Invention
25 [0008] The power supply according to the present
disclosure has an effect of preventing excessive inrush
current from flowing into the storage battery even upon the
switchover from the constant-voltage mode to the currentlimiting mode.
30
Brief Description of Drawings
[0009] FIG. 1 is a diagram illustrating a configuration
example of a power supply according to an embodiment.
5
FIG. 2 is a diagram illustrating a first configuration
example of a power supply source that generates input power
for a Direct Current (DC) to DC converter illustrated in
FIG. 1.
5 FIG. 3 is a diagram illustrating a second
configuration example of the power supply source that
generates the input power for the DC-to-DC converter
illustrated in FIG. 1.
FIG. 4 is a block diagram illustrating a configuration
10 example of control circuitry that implements functions of a
controller according to the embodiment.
FIG. 5 is a first diagram that is used for describing
operation of an essential part of the power supply
according to the embodiment.
15 FIG. 6 is a second diagram that is used for describing
the operation of the essential part of the power supply
according to the embodiment.
FIG. 7 is a block diagram illustrating a functional
configuration example of software that implements the
20 functions of the controller according to the embodiment.
FIG. 8 is a flowchart illustrating an example of a
process flow when the software implements the functions of
the controller according to the embodiment.
FIG. 9 is a block diagram illustrating an example of a
25 hardware configuration when the software implements the
functions of the controller according to the embodiment.
Description of Embodiment
[0010] With reference to the accompanying drawings, a
30 detailed description is hereinafter provided of a power
supply according to an embodiment of the present disclosure.
The embodiment described below is illustrative and is not
restrictive of the scope of the present disclosure.
6
[0011] Embodiment.
FIG. 1 is a diagram illustrating a configuration
example of a power supply 1 according to an embodiment. As
illustrated in FIG. 1, the power supply 1 according to the
5 embodiment includes a DC-to-DC converter 11. The DC-to-DC
converter 11 is a given example of a power converter that
converts input power into direct-current power. The DC-toDC converter 11 includes a switching element 11a. The DCto-DC converter 11 and a load 52 are connected by two
10 electrical wires 15. A storage battery 51 is connected to
the electrical wires 15. While various circuit
configurations are conceivable for the DC-to-DC converter
11, any type of circuit configuration may be used as long
as a circuit that converts the input power into the direct15 current power is included.
[0012] The load 52 is a direct-current load among
auxiliary loads and operates by being supplied with the
direct-current power. Examples of the direct-current load
include a storage battery, a control power supply, and a
20 lighting fixture, among others. In FIG. 1, the storage
battery 51, which is one of a plurality of the directcurrent loads, is illustrated separately from the load 52.
The term “auxiliary loads” refers to loads other than main
motors that are installed on railway vehicles. The
25 auxiliary loads also include alternating-current loads that
operate by being supplied with alternating-current power.
Examples of the alternating-current load include a door
opening and shutting device, an air conditioner, safety
equipment, a compressor, and a lighting fixture that is not
30 a direct-current load, among others.
[0013] As described above, the power supply 1 includes
the DC-to-DC converter 11. The DC-to-DC converter 11
charges the storage battery 51, which is one of the direct-
7
current loads, while supplying the direct-current power to
the direct-current loads installed on the railway vehicle.
[0014] The power supply 1 includes a controller 12, a
voltage sensor 13, and a current sensor 14. The voltage
5 sensor 13 is connected between the two electrical wires 15
and detects direct-current voltage that the DC-to-DC
converter 11 applies to the storage battery 51. The
current sensor 14 is inserted into either of the two
electrical wires 15 and detects current flowing between the
10 DC-to-DC converter 11 and the storage battery 51. The
controller 12 performs operation control on the DC-to-DC
converter 11 on the basis of a detection value Vdc of the
voltage sensor 13 and a detection value Idc of the current
sensor 14. The controller 12 controls the charging of the
15 storage battery 51 through the control of the DC-to-DC
converter 11.
[0015] The power supply 1 has at least two operating
modes for controlling the charging of the storage battery
51. One is a “constant-voltage mode”, and another is a
20 “current-limiting mode”. The constant-voltage mode is an
operating mode in which the storage battery 51 is charged
at a constant voltage. The current-limiting mode is an
operating mode in which the storage battery 51 is charged
with an upper limit specified for charging current involved
25 in the charging of the storage battery 51. In both these
operating modes, namely the constant-voltage mode and the
current-limiting mode, a conduction ratio command is
controlled. The conduction ratio command is a value
commanding a conduction ratio of a gate signal GS that
30 operates the switching element 11a.
[0016] FIG. 2 is a diagram illustrating a first
configuration example of a power supply source that
generates the input power for the DC-to-DC converter 11
8
illustrated in FIG. 1. In the first configuration example
illustrated in FIG. 2, direct-current power supplied from a
direct-current overhead line 60 is received via a collector
61. The received direct-current power is converted into
5 alternating-current power by a single-phase inverter 70.
The converted alternating-current power is stepped down by
a transformer 72 and then supplied to a single-phase
converter 81. The stepped-down alternating-current power
is converted into the direct-current power by the single10 phase converter 81 and then supplied to the DC-to-DC
converter 11.
[0017] FIG. 3 is a diagram illustrating a second
configuration example of the power supply source that
generates the input power for the DC-to-DC converter 11
15 illustrated in FIG. 1. The second configuration example
illustrated in FIG. 3 has an alternating-current overhead
line 60A replacing the direct-current overhead line 60 and
an alternating-current collector 61A replacing the directcurrent collector 61. A comparison between the
20 configuration illustrated in FIG. 3 and the configuration
illustrated in FIG. 2 shows that in FIG. 3, a transformer
71 and a single-phase converter 74 are provided in this
order between the collector 61A and the single-phase
inverter 70. Alternating-current power supplied from the
25 overhead line 60A is received by the transformer 71 via the
collector 61A. The received alternating-current power is
stepped down by the transformer 71 and then supplied to the
single-phase converter 74. The stepped-down alternatingcurrent power is converted into direct-current power by the
30 single-phase converter 74 and then supplied to the singlephase inverter 70. Subsequent operations are the same as
those in FIG. 2. In FIGS. 2 and 3, the common components,
namely the single-phase inverter 70, the transformer 72,
9
and the single-phase converter 81, are denoted by the same
reference characters. However, it goes without saying that
capacity or a configuration of each of the components
differs depending on overhead line voltage, a frequency of
5 the overhead line voltage, and a difference in number of
phases of the overhead line voltage.
[0018] A description is provided next of how the
controller 12 according to the embodiment is configured and
operates. FIG. 4 is a block diagram illustrating a
10 configuration example of control circuitry that implements
functions of the controller 12 according to the embodiment.
The controller 12 includes: a constant-voltage mode control
block 2 as a first control block; a current-limiting mode
control block 3 as a second control block; a switch 41; a
15 conduction ratio command computer 42; and a gate signal
generator 43.
[0019] The constant-voltage mode control block 2 is a
controller that controls the constant-voltage mode and
includes a subtracter 21. The current-limiting mode
20 control block 3 is a controller that controls the currentlimiting mode and includes: subtracters 31 and 32; a
primary lag block 33; a switch 34; an adder 35; and a
comparator 36. In this description, the constant-voltage
mode control block 2 may be referred to as the “first
25 control block”, and the current-limiting mode control block
3 may be referred to as the “second control block”.
[0020] In the constant-voltage mode control block 2, the
subtracter 21 generates a first deviation signal ΔVe that
is a signal representing a deviation between a command
value Vdc* 30 for the direct-current voltage and the detection
value Vdc of the voltage sensor 13. The first deviation
signal ΔVe is input to the switch 41 as an output of the
constant-voltage mode control block 2. In other words, the
10
constant-voltage mode control block 2 is configured so that
the first deviation signal ΔVe becomes an input signal for
the conduction ratio command computer 42. Furthermore, the
first deviation signal ΔVe becomes an input signal for the
5 current-limiting mode control block 3.
[0021] In the current-limiting mode control block 3, the
subtracter 31 generates a second deviation signal ΔIe1 that
is a signal representing a deviation between a command
value IL* for the charging current and the detection value
10 Idc of the current sensor 14. The subtracter 32 generates
a deviation difference signal Δdev1 that is a signal
representing a difference between the second deviation
signal ΔIe1 and the first deviation signal ΔVe. The
deviation difference signal Δdev1 is input to the primary
15 lag block 33, the switch 34, and the comparator 36. A
transfer function of the primary lag block 33 can be
expressed by 1/(1+Ts), using a time constant T and a
Laplace operator s.
[0022] The primary lag block 33 generates a primary lag
20 signal Δdev2 by applying filtering using a primary lag
filter to the deviation difference signal Δdev1. The
primary lag signal Δdev2 is input to the switch 34.
[0023] The comparator 36 generates an output switching
signal SW1 based on the deviation difference signal Δdev1.
25 Specifically, the comparator 36 compares the deviation
difference signal Δdev1 with a zero-valued comparison
determination value. When the deviation difference signal
Δdev1 is less than or equal to the determination value, the
output switching signal SW1 that is generated switches the
30 switch 34 to a “Low” side. In this case, the deviation
difference signal Δdev1 is input to the adder 35.
Therefore, the adder 35 outputs a signal adding the
deviation difference signal Δdev1 (=ΔIe1-ΔVe) and the first
11
deviation signal ΔVe, namely the second difference signal
ΔIe1. On the other hand, when the deviation difference
signal Δdev1 is greater than the determination value, the
output switching signal SW1, which switches the switch 34
5 to a “High” side, is generated. In this case, the primary
lag signal Δdev2 is input to the adder 35. Therefore, the
adder 35 outputs an addition signal adding the primary lag
signal Δdev2 and the first deviation signal ΔVe.
[0024] When the deviation difference signal Δdev1 is
10 equal to the determination value, the switch 34 is switched
to the “Low” side in the above description but may be
switched to the “High” side. In other words, when the
deviation difference signal Δdev1 is equal to the
determination value, the switch 34 may be switched to
15 either the “Low” or “High” side.
[0025] As described above, the current-limiting mode
control block 3 is configured so that when the deviation
difference signal Δdev1 is less than the determination
value, the second deviation signal ΔIe1 becomes an input
20 signal ΔIe2 for the conduction ratio command computer 42.
Furthermore, the configuration of the current-limiting mode
control block 3 is such that when the deviation difference
signal Δdev1 is greater than the determination value, the
signal adding the primary lag signal Δdev2 and the first
25 deviation signal ΔVe becomes the input signal ΔIe2 for the
conduction ratio command computer 42. The second deviation
signal ΔIe1 or the signal adding the primary lag signal
Δdev2 and the first deviation signal ΔVe is input to the
switch 41 as an output of the current-limiting mode control
30 block 3.
[0026] A mode switching signal SW2 that is output when
the operating mode is switched is input to the switch 41.
When the mode switching signal SW2 indicates a switchover
12
from the constant-voltage mode to the current-limiting mode,
the switch 41 is switched to a “High” side. When the mode
switching signal SW2 indicates a switchover from the
current-limiting mode to the constant-voltage mode, the
5 switch 41 is switched to a “Low” side. Therefore, when the
constant-voltage mode is indicated as the operating mode,
the output of the constant-voltage mode control block 2 is
input to the conduction ratio command computer 42. When
the current-limiting mode is indicated as the operating
10 mode, the output of the current-limiting mode control block
3 is input to the conduction ratio command computer 42.
[0027] The conduction ratio command computer 42 computes
the conduction ratio command based on the output of either
the constant-voltage mode control block 2 or the current15 limiting mode control block 3. The gate signal generator
43 generates the gate signal GS based on the conduction
ratio command. The gate signal GS is output to the DC-toDC converter 11 for the DC-to-DC converter 11 to operate on
the basis of the gate signal GS, thus controlling charging
20 voltage or the charging current involved in the charging of
the storage battery 51 to achieve a desired value.
[0028] With reference to FIGS. 5 and 6, a description is
provided next of operation of an essential part of the
power supply 1 according to the embodiment. FIG. 5 is a
25 first diagram that is used for describing the operation of
the essential part of the power supply 1 according to the
embodiment. FIG. 6 is a second diagram that is used for
describing the operation of the essential part of the power
supply 1 according to the embodiment.
30 [0029] FIGS. 5 and 6 illustrate operating waveforms when
the operating mode is switched from the constant-voltage
mode to the current-limiting mode. FIGS. 5 and 6 have
different magnitude relations between the first deviation
13
signal ΔVe and the second deviation signal ΔIe1, with FIG.
5 illustrating a case where ΔIe1>ΔVe and FIG. 6
illustrating a case where ΔIe1≤ΔVe. Each of FIGS. 5 and 6
illustrates, in a top section, a waveform of an input
5 signal for the conduction ratio command computer 42 for a
case where the primary lag block 33 is not included.
Illustrated in a bottom section of each of FIGS. 5 and 6 is
a waveform of the input signal for the conduction ratio
command computer 42 for the case where the above-described
10 primary lag block 33 is included. A broken line is
illustrated in the bottom section of FIG. 5, representing
the waveform of the second deviation signal ΔIe1
illustrated in the top section of FIG. 5 for comparison.
[0030] As mentioned earlier, the first deviation signal
15 ΔVe is the signal that represents the voltage deviation,
while the second deviation signal ΔIe1 is the signal that
represents the current deviation. These signals have
different values unless their values match by coincidence.
Therefore, in the absence of the primary lag block 33, a
20 step-up is caused to the signal that is input to the
conduction ratio command computer 42 at the moment the
operating mode is switched from the constant-voltage mode
to the current-limiting mode. This means that the
conduction ratio of the gate signal GS, which is input to
25 the DC-to-DC converter 11, experiences a sharp step-up. As
a result, excessive inrush current may flow into the
storage battery 51. In contrast, in the presence of the
primary lag block 33, the output of the primary lag block
33 is a waveform that gently rises due to the time constant
30 T. Therefore, the input signal ΔIe2 for the conduction
ratio command computer 42, too, becomes the waveform that
gently rises due to the time constant T, as illustrated in
the bottom section of FIG. 5, suppressing a sharp change to
14
the conduction ratio of the gate signal GS. As a result,
the excessive inrush current can be prevented from flowing
into the storage battery 51.
[0031] As described earlier, when ΔIe1≤ΔVe, the input
5 signal ΔIe2 for the conduction ratio command computer 42 is
the signal that has not gone through the primary lag block
33. Therefore, a step-down is caused to the signal that is
input to the conduction ratio command computer 42 at the
moment the operating mode is switched from the constant10 voltage mode to the current-limiting mode. This means that
the conduction ratio of the gate signal GS, which is input
to the DC-to-DC converter 11, is stepped down, and this
control is important. Reasons for this are explained below.
[0032] Consider a case where a short circuit occurs at
15 the load 52 here. When such a short circuit occurs, in
order to prevent short-circuit current from damaging a
circuit network, the operating mode needs to be switched
from the constant-voltage mode to the current-limiting mode
to quickly step down the conduction ratio of the gate
20 signal GS. However, the primary lag block 33 acts toward
restraining the step-down of the conduction ratio of the
gate signal GS and thus negatively acts on short-circuit
current restraint. Therefore, in the present embodiment,
even when the operating mode has been switched from the
25 constant-voltage mode to the current-limiting mode, the
primary lag block 33 is not gone through if ΔIe1≤ΔVe. This
produces an effect of not adversely affecting the shortcircuit current restraint while excessive inrush current is
prevented from flowing into the storage battery 51.
30 [0033] While the above explanation pertains to the case
where the short circuit occurs at the load 52, but it is
also effective against an output current overshoot that is
caused by instantaneous capacity fluctuation of the load 52.
15
In other words, the use of the technique according to the
present embodiment also provides the effect of restraining
the output current overshoot that is caused by the
instantaneous capacity fluctuation of the load 52.
5 [0034] While the configuration example of the control
circuitry that implements the functions of the controller
12 according to the embodiment has been described with FIG.
4, the functions of the controller 12 may be implemented by
software. FIG. 7 is a block diagram illustrating a
10 functional configuration example of the software that
implements the functions of the controller 12 according to
the embodiment. FIG. 8 is a flowchart illustrating an
example of a process flow when the software implements the
functions of the controller 12 according to the embodiment.
15 As illustrated in FIG. 7, the functions of the controller
12 according to the embodiment can be constructed by being
divided into a control computer 121 and a conduction ratio
command computer 122. The control computer 121 and the
conduction ratio command computer 122 operate according to
20 the flowchart of FIG. 8. With reference to FIG. 8, a
description is provided of the process flow.
[0035] First, the control computer 121 computes the
first deviation signal ΔVe, the second deviation signal
ΔIe1, the deviation difference signal Δdev1, and the
25 primary lag signal Δdev2 that have been described above and
also computes the addition signal Δdev2+ΔVe, which is the
primary lag signal Δdev2 plus the first deviation signal
ΔVe (step S11). The control computer 121 checks whether or
not there is the mode switching signal SW2 (step S12). If
30 there is no mode switching signal SW2 (step S13, No), a
return is made to step S11, and the operations of steps S11
and S12 are repeated. If, on the other hand, there is the
mode switching signal SW2 (step S13, Yes), the control
16
computer 121 determines whether or not the switchover is
from the constant-voltage mode to the current-limiting mode
(step S14). If the switchover is not from the constantvoltage mode to the current-limiting mode (step S14, No),
5 the control computer 121 selects the first deviation signal
ΔVe as the input signal for the conduction ratio command
computer 42 (step S18). A return is made to step S11
thereafter, and the operations are repeated, starting from
step S11.
10 [0036] If at step S14, the switchover is from the
constant-voltage mode to the current-limiting mode (step
S14, Yes), the control computer 121 further checks the
magnitude relation between the first deviation signal ΔVe
and the second deviation signal ΔIe1. If ΔIe1>ΔVe (step
15 S15, Yes), the control computer 121 selects the addition
signal Δdev2+ΔVe as the input signal for the conduction
ratio command computer 42 (step S16). A return is made to
step S11 thereafter, and the operations are repeated,
starting from step S11. If ΔIe1≤ΔVe (step S15, No), the
20 control computer 121 selects the second deviation signal
ΔIe1 as the input signal for the conduction ratio command
computer 42 (step S17). A return is made to step S11
thereafter, and the operations are repeated, starting from
step S11.
25 [0037] In the above description, for the sake of
simplicity, the voltage and the current, which are physical
quantities of different unit systems, have been compared.
However, these different physical quantities are compared
as data normalized with sensor ratios or gains. It is to
30 be noted that the physical quantities to be used for the
comparison are not limited to these examples, namely the
voltage and the current. Any physical quantities may be
used for the comparison.
17
[0038] FIG. 9 is a block diagram illustrating an example
of a hardware configuration when the software implements
the functions of the controller 12 according to the
embodiment. In order for the software to implement the
5 functions of the controller 12 according to the embodiment,
the configuration can include, as illustrated in FIG. 9, a
processor 300 that performs computations, a memory 302 that
stores programs to be read by the processor 300 and
determination value–related data to be read, and an
10 interface 304 for input and output of signals.
[0039] The processor 300 is, for example, an arithmetic
means such as an arithmetic unit, a microprocessor, a
microcomputer, a central processing unit (CPU), or a
digital signal processor (DSP). The memory 302 can be, for
15 example, a nonvolatile or volatile semiconductor memory
such as a random-access memory (RAM), a read-only memory
(ROM), a flash memory, an erasable programmable ROM (EPROM),
or an electrically EPROM (EEPROM) (registered trademark), a
magnetic disk, a flexible disk, an optical disk, a compact
20 disk, a mini disk, or a digital versatile disc (DVD).
[0040] The processor 300 transmits and receives
necessary information via the interface 304 and executes
the programs stored in the memory 302. By referring to the
determination value–related data stored in the memory 302,
25 the processor 300 is capable of executing the sequential
process flow illustrated in FIG. 8.
[0041] As described above, the power supply according to
the embodiment has the operating modes that include the
constant-voltage mode where the storage battery is charged
30 at the constant voltage and the current-limiting mode where
the storage battery is charged with the upper limit
specified for the charging current for the storage battery.
The controller includes the first control block that
18
controls the constant-voltage mode, the second control
block that controls the current-limiting mode, and the
conduction ratio command computer that computes the
conduction ratio command based on the output of either the
5 first control block or the second control block. The
conduction ratio command is the value commanding the
conduction ratio of the gate signal that operates the
switching element included in the power converter. The
second control block includes the primary lag block that
10 allows the signal to go through for input to the conduction
ratio command computer upon an operating mode switchover
from the constant-voltage mode to the current-limiting mode.
With this configuration, the signal that is input to the
conduction ratio command computer goes through the primary
15 lag block the moment that the operating mode is switched
from the constant-voltage mode to the current-limiting mode
if there is a possibility of a step-up in the input signal.
As a result of this operation, the step-up in the input
signal for the conduction ratio command computer is avoided,
20 thus leading to the prevention of a sharp change to the
conduction ratio of the gate signal, which is input to the
power converter. Consequently, the effect of preventing
the excessive inrush current from flowing into the storage
battery is obtained.
25 [0042] When the operating mode has been switched from
the constant-voltage mode to the current-limiting mode, the
signal that is input to the conduction ratio command
computer goes through the primary lag block; however, the
signal that is input to the conduction ratio command
30 computer does not go through the primary lag block when
ΔIe1≤ΔVe as in the case where the short circuit occurs at
the load 52. When the signal is to be stepped down for
input to the conduction ratio command computer, restraining
19
the step-down of the conduction ratio of the gate signal,
which is input to the power converter, is avoided thus.
Consequently, the effect of not adversely affecting the
short-circuit current restraint is obtained while the
5 excessive inrush current is prevented from flowing into the
storage battery. Furthermore, the effect of restraining
the output current overshoot that is caused by the
instantaneous capacity fluctuation of the load is obtained.
[0043] In the first control block included in the
10 controller of the power supply according to the first
embodiment, the first deviation signal is generated as the
signal representing the deviation between the command value
for the direct-current voltage and the detection value of
the voltage sensor. The first control block is configured
15 so that the first deviation signal becomes the input signal
for the conduction ratio command computer. In the second
control block included in the controller, the second
deviation signal is generated as the signal representing
the deviation between the command value for the charging
20 current and the detection value of the current sensor. In
the second control block, the deviation difference signal
is input to the primary lag block as the signal
representing the difference between the second deviation
signal and the first deviation signal, and the primary lag
25 signal resulting from the deviation difference signal is
output from the primary lag block. In the second control
block, the deviation difference signal and the
determination value are compared. When the deviation
difference signal is less than or equal to the
30 determination value, the second deviation signal is
selected as the input signal for the conduction ratio
command computer. When, on the other hand, the deviation
difference signal is greater than the determination value,
20
the addition signal adding the primary lag signal and the
first deviation signal is selected as the input signal for
the conduction ratio command computer. According to these
controls, the three operations are performed concurrently,
5 including the operation of allowing the deviation
difference signal to go through the primary lag block, the
bypass operation for the deviation signal to not go through
the primary lag block, and the operation of comparing the
deviation difference signal and the determination value.
10 This produces an effect of preventing, with a reduced time
lag, the conduction ratio of the gate signal from
experiencing a sharp step-up upon the switchover from the
constant-voltage mode to the current-limiting mode.
Moreover, an effect of configuring the controller with no
15 significant modifications to existing functions is obtained.
[0044] The controller of the power supply according to
the embodiment includes the control computer and the
conduction ratio command computer. The control computer
computes the first deviation signal, the second deviation
20 signal, and the deviation difference signal that have been
described earlier. Furthermore, the control computer
computes the primary lag signal by applying the filtering
using the primary lag filter to the deviation difference
signal and computes the addition signal, which is the
25 primary lag signal plus the first deviation signal. On the
basis of one of the first deviation signal, the second
deviation signal, and the addition signal, the conduction
ratio command computer computes the conduction ratio
command to be used in the generation of the gate signal,
30 which operates the switching element included in the power
converter. When the operating mode has been switched from
the constant-voltage mode to the current-limiting mode, the
controller selects the addition signal as the input signal
21
for the conduction ratio command computer while the second
deviation signal is greater than the first deviation signal.
As a result of this operation, a step-up in the input
signal for the conduction ratio command computer is avoided,
5 thus leading to the prevention of a sharp change to the
conduction ratio of the gate signal, which is input to the
power converter. Consequently, the effect of preventing
the excessive inrush current from flowing into the storage
battery is obtained.
10 [0045] Even when the operating mode has been switched
from the constant-voltage mode to the current-limiting mode,
the controller selects the second deviation signal as the
input signal for the conduction ratio command computer
while the second deviation signal is less than or equal to
15 the first deviation signal. With this operation, when the
signal is to be stepped down for input to the conduction
ratio command computer, restraining a step-down of the
conduction ratio of the gate signal, which is input to the
power converter, is avoided. Consequently, the effect of
20 not adversely affecting the short-circuit current restraint
is obtained while the excessive inrush current is prevented
from flowing into the storage battery. Furthermore, the
effect of restraining the output current overshoot that is
caused by the instantaneous capacity fluctuation of the
25 load is obtained.
[0046] The above configurations illustrated in the
embodiment are illustrative, can be combined with other
techniques that are publicly known, and can be partly
omitted or changed without departing from the gist.
30
Reference Signs List
[0047] 1 power supply; 2 constant-voltage mode control
block; 3 current-limiting mode control block; 11 DC-to-DC
22
converter; 11a switching element; 12 controller; 13
voltage sensor; 14 current sensor; 15 electrical wire; 21,
31, 32 subtracter; 33 primary lag block; 34, 41 switch;
35 adder; 36 comparator; 42, 122 conduction ratio command
5 computer; 43 gate signal generator; 51 storage battery;
52 load; 60, 60A overhead line; 61, 61A collector; 70
single-phase inverter; 71, 72 transformer; 74, 81 singlephase converter; 121 control computer; 300 processor; 302
memory; 304 interface.

We Claim:
[Claim 1] A power supply equipped with a power converter
adapted to supply direct-current power to a load to be
5 installed on a railway vehicle while charging a storage
battery as one of a plurality of the loads, the power
supply comprising:
a voltage sensor adapted to detect direct-current
voltage that the power converter applies to the storage
10 battery;
a current sensor adapted to detect current flowing
between the power converter and the storage battery; and
a controller adapted to control charging of the
storage battery on a basis of a detection value of the
15 voltage sensor and a detection value of the current sensor,
wherein
the power supply has operating modes including:
a constant-voltage mode where the storage battery
is charged at a constant voltage; and
20 a current-limiting mode where the storage battery
is charged with an upper limit specified for charging
current for the storage battery,
the controller includes:
a first control block adapted to control the
25 constant-voltage mode;
a second control block adapted to control the
current-limiting mode; and
a conduction ratio command computer adapted to
compute a conduction ratio command based on an output of
30 either the first control block or the second control block,
the conduction ratio command being a value commanding a
conduction ratio of a gate signal that operates a switching
element included in the power converter, wherein
24
the second control block includes
a primary lag block adapted to allow an input signal
to the conduction ratio command computer upon an operating
mode switchover from the constant-voltage mode to the
5 current-limiting mode.
[Claim 2] The power supply according to claim 1, wherein
the input signal to the conduction ratio command
computer does not go through the primary lag block upon an
10 operating mode switchover from the current-limiting mode to
the constant-voltage mode.
[Claim 3] The power supply according to claim 1 or 2,
wherein
15 when the operating mode is the constant-voltage mode,
the output of the first control block is input to the
conduction ratio command computer, and
when the operating mode is the current-limiting mode,
the output of the second control block is input to the
20 conduction ratio command computer.
[Claim 4] The power supply according to claim 2 or 3,
wherein
a first deviation signal is generated in the first
25 control block as a signal representing a deviation between
a command value for the direct-current voltage and the
detection value of the voltage sensor,
a second deviation signal is generated in the second
control block as a signal representing a deviation between
30 a command value for the charging current and the detection
value of the current sensor,
as a deviation difference signal is input to the
primary lag block as a signal representing a difference
25
between the second deviation signal and the first deviation
signal, a primary lag signal resulting from the deviation
difference signal is output from the primary lag block,
the first control block is configured so that the
5 first deviation signal becomes an input signal to the
conduction ratio command computer, and
the second control block is configured so that one of:
the second deviation signal; and
an addition signal adding the primary lag signal
10 and the first deviation signal becomes an input signal to
the conduction ratio command computer.
[Claim 5] The power supply according to claim 4, wherein
in the second control block, the deviation difference
15 signal and a determination value are compared:
the second deviation signal is selected when the
deviation difference signal is less than the determination
value; and
the addition signal is selected when the
20 deviation difference signal is greater than the
determination value.
[Claim 6] A power supply equipped with a power converter
that supplies direct-current power to a load to be
25 installed on a railway vehicle while charging a storage
battery as one of a plurality of the loads, the power
supply comprising:
a voltage sensor adapted to detect direct-current
voltage that the power converter applies to the storage
30 battery;
a current sensor adapted to detect current flowing
between the power converter and the storage battery; and
a controller adapted to control the storage battery
26
charging on a basis of the detection value of the voltage
sensor and the detection value of the current sensor,
wherein
the power supply has operating modes including:
5 a constant-voltage mode where the storage battery
is charged at a constant voltage; and
a current-limiting mode where the storage battery
is charged with an upper limit specified for charging
current for the storage battery,
10 the controller includes,
a control computer adapted to compute:
a first deviation signal as a signal representing
a deviation between the detection value of the voltage
sensor and a command value for the direct-current voltage;
15 a second deviation signal as a signal
representing a deviation between the detection value of the
current sensor and a command value for the charging current
involved in the storage battery charging;
a deviation difference signal as a difference
20 between the second deviation signal and the first deviation
signal;
a primary lag signal as a result of applying
filtering using a primary lag filter to the deviation
difference signal; and
25 an addition signal as the primary lag signal plus
the first deviation signal, and
the controller further includes,
a conduction ratio command computer adapted to
compute a basis of one of the first deviation signal, the
30 second deviation signal, and the addition signal, a
conduction ratio command to be used in generation of a gate
signal that operates a switching element included in the
power converter, wherein
27
when an operating mode switchover from the constantvoltage mode to the current-limiting mode has occurred, the
control computer is adapted to select the addition signal
as an input signal to the conduction ratio command computer
5 while the second deviation signal is greater than the first
deviation signal.
[Claim 7] The power supply according to claim 6, wherein
even when the operating mode switchover has been made
10 from the constant-voltage mode to the current-limiting mode,
the control computer is adapted to select the second
deviation signal as an input signal to the conduction ratio
command computer while the second deviation signal is less
than the first deviation signal.