FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
POWER CONVERSION DEVICE;
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
Technical Field
[0001] The present disclosure relates to a power conversion device.
5 Background Art
[0002] Some electric railway vehicles are equipped with a power conversion device
that converts electric power supplied from a substation via overhead lines into desired
direct-current (DC) electric power or alternating-current (AC) electric power and supplies
the DC electric power or the AC electric power to a load. One example of this type of
10 power conversion device is disclosed in Patent Literature 1. This power conversion
device includes two power converters and two filter capacitors. Each of the power
converters converts DC electric power supplied via a primary terminal from a power
source into AC electric power, and supplies the AC electric power to a load connected to
a secondary terminal. Each of the filter capacitors is connected to the primary terminal
15 of the corresponding power converter and is charged with electric power supplied by the
power source. This power conversion device also includes a contactor that electrically
connects the two power converters to the power source or disconnects the two power
converters from the power source.
Citation List
20 Patent Literature
[0003] Patent Literature 1: Unexamined Japanese Patent Application Publication
No. 2017-221058
Summary of Invention
Technical Problem
25 [0004] The power converters of the power conversion device disclosed in Patent
Literature 1 are provided with redundancy. Specifically, one of the power converters is
set as an operation-system power converter and the other power converter is set as a
3
standby-system power converter. More specifically, the power conversion device
controls switching elements of the operation-system power converter to operate the
operation-system power converter to convert the DC electric power into the AC electric
power. In a case where the operation-system power converter fails, operation of the
5 standby-system power converter enables continuation of the power conversion
processing by the power conversion device.
[0005] However, the power converters of this power conversion device are
redundant, while only a single contactor is provided. Thus failure of the contactor
results in inability for the power conversion device to continue the power conversion
10 processing. In other words, redundancy of this power conversion device is insufficient.
[0006] In view of the above circumstances, an objective of the present disclosure is
to provide a power conversion device with high redundancy.
Solution to Problem
[0007] To achieve the above objective, a power conversion device of the present
15 disclosure includes a plurality of power conversion units, a contactor controller, and a
sensor. Each of the plurality of power conversion units includes a power converter, a
contactor, and a unit controller. The power converter converts electric power supplied
from a power source into electric power for supply to a load and supplies the converted
electric power to the load. The contactor electrically connects the power converter to
20 the power source or electrically disconnects the power converter from the power source.
The unit controller controls switching elements included in the power converter. The
plurality of power conversion unit is configured to be connected in common to the power
source. The contactor controller closes or opens the contactor included in each of the
plurality of power conversion units. The sensor measures a value of at least one of input
25 current or output current of the power converter included in each of the plurality of power
conversion units, and outputs the measured value of the at least one of the input current or
the output current of the power converter. The unit controllers of the plurality of power
4
conversion units are connected to one another through a transmission line. Each of the
unit controllers determines presence or absence of a failure of the power conversion unit
based on the measured value of the at least one of the input current or the output current
of the power converter that is a control target and whether the contactor associated with
5 the power converter that is the control target is in a closed state or an open state, and
sends a determination result to another unit controller of the unit controllers.
Advantageous Effects of Invention
[0008] Since the power conversion device according to the present disclosure
10 includes the plurality of power conversion units each including a power converter and a
contactor and configured to be connected in common to the power source, the power
conversion device with high redundancy can be provided.
Brief Description of Drawings
[0009] FIG. 1 is a block diagram of a power conversion device according to
15 Embodiment 1;
FIG. 2 is a perspective view of an input current sensor according to Embodiment 1;
FIG. 3 is a cross-sectional view of the input current sensor according to
Embodiment 1;
FIG. 4 is a sequence diagram illustrating communication between unit controllers
20 according to Embodiment 1;
FIG. 5 is a block diagram of a power conversion device according to Embodiment
2;
FIG. 6 is a sequence diagram illustrating communication between unit controllers
according to Embodiment 2;
25 FIG. 7 is a block diagram of a power conversion device according to Embodiment
3;
FIG. 8 is a perspective view of an input current sensor according to Embodiment 3;
5
FIG. 9 is a block diagram of a power conversion device according to Embodiment
4;
FIG. 10 is a perspective view of an output current sensor according to Embodiment
4;
5 FIG. 11 is a cross-sectional diagram of the output current sensor according to
Embodiment 4;
FIG. 12 is a block diagram of a power conversion device according to
Embodiment 5; and
FIG. 13 is a perspective view of an output current sensor according to Embodiment
10 5.
Description of Embodiments
[0010] A power conversion device according to embodiments of the present
disclosure is hereinafter described in detail with reference to the drawings. The same
reference numerals are used throughout the drawings to refer to the same or equivalent
15 components.
[0011] Embodiment 1
A power conversion device 1 according to Embodiment 1 is described using as an
example a power conversion device to be mounted on a vehicle, specifically, a power
conversion device mounted on a DC feeding system of an electric railway vehicle. The
20 power conversion device 1 illustrated in FIG. 1 converts DC electric power supplied from
a power source into electric power for supply to a load and supplies the electric power to
the load. In Embodiment 1, a current collector 52 that acquires electric power via an
overhead line 51 from a substation corresponds to the power source. The current
collector 52 is, for example, a pantograph. An electric motor 53 that receives supply of
25 the electric power from the power conversion device 1 to operate and generates
propulsion of the electric railway vehicle corresponds to the load. The electric motor 53
is, for example, a three-phase induction motor. Specifically, the power conversion
6
device 1 converts DC electric power supplied from the current collector 52 into electric
power for supply to the electric motor 53, for example, three-phase AC electric power,
and supplies the three-phase AC electric power to the electric motor 53.
[0012] The power conversion device 1 includes a plurality of power conversion
5 units 10 and 20 to enhance redundancy. One of the power conversion units 10 and 20 is
set as an operation-system unit and the other one of the power conversion units 10 and 20
is set as a standby-system unit. The power conversion units 10 and 20 are connected in
common to the current collector 52. The power conversion units 10 and 20 are
connected in common to the electric motor 53 via a later-described switcher 31.
10 [0013] For example, the power conversion unit 10 is set as an operation-system unit
and the power conversion unit 20 is set as a standby-system unit. In this case, the power
conversion unit 10 converts DC electric power supplied from the current collector 52 into
three-phase AC electric power and supplies the three-phase AC electric power to the
electric motor 53. While the power conversion unit 10 performs power conversion
15 processing, the power conversion unit 20 does not perform power conversion processing.
Upon occurrence of a failure of the power conversion unit 10, the power conversion unit
20 is set as the operation-system unit so that the power conversion unit 20 then starts
power conversion processing. Specifically, the power conversion unit 20 converts DC
electric power supplied from the current collector 52 into three-phase AC electric power
20 and supplies the three-phase AC electric power to the electric motor 53.
[0014] A configuration of the power conversion device 1 is described below. The
power conversion device 1 includes a positive input terminal 1a connected to the current
collector 52 and a negative input terminal 1b connected to the ground. The power
conversion units 10 and 20 receive supply of DC electric power via the positive input
25 terminal 1a from the current collector 52, converts the DC electric power into three-phase
AC electric power, and supplies the three-phase AC electric power to the electric motor
53.
7
[0015] The power conversion unit 10 includes a power converter 11 that converts
the DC electric power supplied via a primary terminal from the current collector 52 into
the three-phase AC electric power for supply to the electric motor 53, and supplies the
three-phase AC electric power through secondary terminals to the electric motor 53, a
5 contactor MC1 that electrically connects the power converter 11 to the current collector
52 or electrically disconnects the power converter 11 from the current collector 52, and a
unit controller 12 that controls switching elements included in the power convertor 11.
[0016] Preferably, the power conversion unit 10 further includes a filter capacitor
FC1 connected between the primary terminals of the power converter 11 and a filter
10 reactor FL1 that, together with the filter capacitor FC1, forms a filter for reducing
harmonics.
[0017] The power conversion unit 20 includes a power converter 21 that converts
the DC electric power supplied via the primary terminal from the current collector 52 into
the three-phase AC electric power for supply to the electric motor 53, and supplies the
15 three-phase AC electric power through the secondary terminals to the electric motor 53, a
contactor MC2 that electrically connects the power converter 21 to the current collector
52 or electrically disconnects the power converter 21 from the current collector 52, and a
unit controller 22 that controls switching elements included in the power convertor 21.
[0018] Preferably, the power conversion unit 20 further includes a filter capacitor
20 FC2 connected between the primary terminals of the power converter 21 and a filter
reactor FL2 that, together with the filter capacitor FC2, forms a filter for reducing
harmonics.
[0019] The power conversion device 1 includes the switcher 31 that electrically
connects either of the power conversion units 10 and 20 to the electric motor 53, a
25 contactor controller 32 that controls the switcher 31 to close or open the contactors MC1
and MC2 included in the power conversion units 10 and 20, respectively, and a sensor 33
that measures at least one of values of input current and output current of each of the
8
power converters 11 and 21 and outputs the measured value. Here, the input current of
the power converter 11 indicates current that flows in the power converter 11 via the
primary terminal of the power converter 11 or current that flows out from the power
converter 11 via the primary terminal of the power converter 11. Similarly, the input
5 current of the power converter 21 indicates current that flows in the power converter 21
via the primary terminal of the power converter 21 or current that flows out from the
power converter 21 via the primary terminal of the power converter 21. Also, the output
current of the power converter 11 indicates current that flows out from the power
converter 11 via the secondary terminal of the power converter 11 or current that flows in
10 the power converter 11 via the secondary terminal of the power converter 11. Similarly,
the output current of the power converter 21 indicates current that flows out from the
power converter 21 via the secondary terminal of the power converter 21 or current that
flows in the power converter 21 via the secondary terminal of the power converter 21.
[0020] In Embodiment 1, the sensor 33 measures a value of the input current of
15 each of the power converters 11 and 21. Specifically, the sensor 33 includes an input
current sensor CT1 that measures a value of the input current of the power converter 11,
specifically, a value of current flowing in an input busbar B1 connecting the filter reactor
FL1 and the power converter 11 and outputs the measured value. The sensor 33 also
includes an input current sensor CT2 that measures a value of the input current of the
20 power converter 21, specifically, a value of current flowing in an input busbar B2
connecting the filter reactor FL2 and the power converter 21 and outputs the measured
value.
[0021] Each component of the power conversion device 1 is described in detail.
The positive input terminal 1a is connected to the current collector 52, which is the power
25 source. The negative input terminal 1b is grounded via, for example, a ground brush, a
wheel, and a rail.
[0022] Each component of the power conversion unit 10 is described. The
9
contactor MC1 has one end connected to the positive input terminal 1a and the other end
connected to one end of the filter reactor FL1. The contactor MC1 is a DC
electromagnetic contactor and is controlled by the contactor controller 32. Specifically,
the contactor MC1 is closed or opened by a contactor control signal S1 output by the
5 contactor controller 32.
[0023] Upon the contactor controller 32 closing the contactor MC1, the one end
and the other end of the contactor MC1 are connected to each other. As a result, the
power converter 11 and the filter capacitor FC1 are electrically connected to the current
collector 52 via the filter reactor FL1, and receive supply of the electric power from the
10 current collector 52. Also, upon the contactor controller 32 opening the contactor MC1,
the one end and the other end of the contactor MC1 are isolated from each other. As a
result, the power converter 11 and the filter capacitor FC1 are electrically disconnected
from the current collector 52 and cannot receive supply of the electric power from the
current collector 52.
15 [0024] The one end of the filter reactor FL1 is connected to the other end of the
contactor MC1, and the other end of the filter reactor FL1 is connected to one of the
primary terminals of the power converter 11 and one end of the filter capacitor FC1.
The filter capacitor FC1 is connected between the primary terminals of the power
converter 11 and charged by the electric power supplied from the current collector 52.
20 Specifically, the one end of the filter capacitor FC1 is connected to a point of connection
between the other end of the filter reactor FL1 and the one of the primary terminals of the
power converter 11. The other end of the filter capacitor FC1 is connected to a point of
connection between the negative input terminal 1b and the other one of the primary
terminals of the power converter 11. The filter reactor FL1 and the filter capacitor FC1
25 form a filter that reduces harmonics.
[0025] The power converter 11 converts the DC electric power supplied via the
primary terminal into the three-phase AC electric power and supplies the three-phase AC
10
electric power from each secondary terminal via the switcher 31 to the electric motor 53.
For example, the power converter 11 is a variable voltage variable frequency (VVVF)
inverter. Specifically, the power converter 11 includes a plurality of switching elements
capable of high-speed switching, for example, insulated gate bipolar transistors (IGBTs).
5 As described later, the plurality of switching elements is controlled by the unit controller
12 to turn on and off repeatedly, so that the power converter 11 converts the DC electric
power into the three-phase AC electric power. Then the power converter 11 supplies
the three-phase electric power via the switcher 31 to the electric motor 53.
[0026] The unit controller 12 acquires a running command from a master controller
10 provided in an unillustrated driver's cab. The running command includes a powering
command indicating a target acceleration of the electric railway vehicle, a brake
command indicating a target deceleration of the electric railway vehicle, and the like.
The unit controller 12 sends, in accordance with the running command, switching control
signals S21 to the switching elements included in the power converter 11 to control the
15 switching elements. The unit controller 12 receives supply of the electric power from
an unillustrated control power source and operates.
[0027] The unit controller 12 determines presence or absence of a failure of the
power conversion unit 10 based on the at least one of the values of the input current and
the output current of the power converter 11 that is a control target and whether the
20 contactor MC1 associated with the power converter 11 is in a closed state or an open state.
In Embodiment 1, the unit controller 12 acquires a value of the input current of the power
converter 11 from the sensor 33. Specifically, the unit controller 12 acquires the
measured value from the input current sensor CT1. The unit controller 12 acquires the
contactor control signal S1 output by the contactor controller 32, and determines, based
25 on the contactor control signal S1, whether the contactor MC1 is in the closed state or the
open state.
[0028] Then the unit controller 12 determines presence or absence of a failure of the
11
power conversion unit 10 based on the measured value of the input current sensor CT1
and whether the contactor MC1 is in the closed state or the open state.
[0029] Specifically, in a case where the contactor MC1 is in the closed state and the
measured value of the input current sensor CT1 has an absolute value that is out of a first
5 current range, the unit controller 12 determines that the failure of the power conversion
unit 10 occurs. The first current range is determined in accordance with a value that
current flowing through the overhead line 51 can have. For example, an upper limit
value of the first current range is 1.5 times as much as a maximum value of the value that
the current flowing through the overhead line 51 can have, and a lower limit value of the
10 first current range is 0.5 times as much as a minimum value of the value that the current
flowing through the overhead line 51 can have. Also, in a case where the contactor
MC1 is in the open state and the measured value of the input current sensor CT1 has an
absolute value that is out of a second current range, the unit controller 12 determines that
the failure of the power conversion unit 10 occurs. The second current range is a
15 sufficiently narrow range having a lower limit value that is zero amps.
[0030] Upon determination of the presence or absence of the failure of the power
conversion unit 10 as described above, the unit controller 12 sends a determination result
to another unit controller, that is, the unit controller 22. Then the unit controller 12
sends the determination result to the contactor controller 32.
20 [0031] Next, each component of the power conversion unit 20 is described. The
contactor MC2 has one end connected to the positive input terminal 1a and the other end
connected to one end of the filter reactor FL2. The contactor MC2 is a DC
electromagnetic contactor and is controlled by the contactor controller 32. Specifically,
the contactor MC2 is closed or opened by the contactor control signal S1 output by the
25 contactor controller 32.
[0032] Upon the contactor controller 32 closing the contactor MC2, the one end
and the other end of the contactor MC2 are connected to each other. As a result, the
12
power converter 21 and the filter capacitor FC2 are electrically connected to the current
collector 52 via the filter reactor FL2 and receive supply of the electric power from the
current collector 52. Also, upon the contactor controller 32 opening the contactor MC2,
the one end and the other end of the contactor MC2 are isolated from each other. As a
5 result, the power converter 21 and the filter capacitor FC2 are electrically disconnected
from the current collector 52 and cannot receive supply of the electric power from the
current collector 52.
[0033] The one end of the filter reactor FL2 is connected to the other end of the
contactor MC2, and the other end of the filter reactor FL2 is connected to one of the
10 primary terminals of the power converter 21 and one end of the filter capacitor FC2.
The filter capacitor FC2 is connected between the primary terminals of the power
converter 21 and charged by the electric power supplied from the current collector 52.
Specifically, the one end of the filter capacitor FC2 is connected to a point of connection
between the other end of the filter reactor FL2 and one of the primary terminals of the
15 power converter 21. The other end of the filter capacitor FC2 is connected to a point of
connection between the negative input terminal 1b and the other one of the primary
terminals of the power converter 21. The filter reactor FL2 and the filter capacitor FC2
form a filter that reduces harmonics.
[0034] The power converter 21 converts the DC electric power supplied via the
20 primary terminal into the three-phase AC electric power and supplies the three-phase AC
electric power from each secondary terminal via the switcher 31 to the electric motor 53.
For example, the power converter 21 is a VVVF inverter. Specifically, the power
converter 21 includes a plurality of switching elements capable of high-speed switching,
for example, IGBTs. As described later, the plurality of switching elements is
25 controlled by the unit controller 22 to turn on and off repeatedly, and thereby the power
converter 21 converts the DC electric power into the three-phase AC electric power.
Then the power converter 21 supplies the three-phase AC electric power via the switcher
13
31 to the electric motor 53.
[0035] The unit controller 22 acquires a running command from a master controller
provided in an unillustrated driver's cab. The unit controller 22 sends, in accordance
with the running command, switching control signals S22 to the switching elements
5 included in the power converter 21 to control the switching elements. The unit
controller 22 receives supply of the electric power from an unillustrated control power
source and operates.
[0036] The unit controller 22 determines presence or absence of a failure of the
power conversion unit 20 based on the at least one of the values of the input current and
10 the output current of the power converter 21 that is a control target and whether the
contactor MC2 associated with the power converter 21 is in the closed state or the open
state. In Embodiment 1, the unit controller 22 acquires a value of the input current of
the power converter 21 from the sensor 33. Specifically, the unit controller 22 acquires
the measured value from the input current sensor CT2. The unit controller 22 acquires
15 the contactor control signal S1 output by the contactor controller 32, and determines,
based on the contactor control signal S1, whether the contactor MC2 is in the closed state
or the open state.
[0037] Then the unit controller 22 determines presence or absence of a failure of the
power conversion unit 20 based on the measured value of the input current sensor CT2
20 and whether the contactor MC2 is in the closed state or the open state.
[0038] Specifically, in a case where the contactor MC2 is in the closed state and the
measured value of the input current sensor CT2 has an absolute value that is out of the
first current range, the unit controller 22 determines that the failure of the power
conversion unit 20 occurs. Also, in a case where the contactor MC2 is in the open state
25 and the measured value of the input current sensor CT2 has an absolute value that is out
of the second current range, the unit controller 22 determines that the failure of the power
conversion unit 20 occurs.
14
[0039] Upon determination of the presence or absence of the failure of the power
conversion unit 20 as described above, the unit controller 22 sends a determination result
to another unit controller, that is, the unit controller 12. Then the unit controller 22
sends the determination result to the contactor controller 32.
5 [0040] Each primary terminal of the switcher 31 is connected to its corresponding
output terminal of the power conversion units 10 and 20, specifically, its corresponding
secondary terminal of the power converter 11 and 21. Each secondary terminal of the
switcher 31 is connected to the electric motor 53. The switcher 31 is controlled by the
contactor controller 32 to electrically connect each primary terminal connected to the
10 power converter 11 to its corresponding secondary terminal or electrically connect each
primary terminal connected to the power converter 21 to its corresponding secondary
terminal.
[0041] The contactor controller 32 closes or opens the contactors MC1 and MC2.
The contactor controller 32 switches the switcher 31 to connect to an operation-system or
15 standby-system unit. An operation instruction signal that provides instruction to start or
stop the power conversion device 1 is supplied from an unillustrated driver's cab to the
contactor controller 32. The contactor controller 32 previously holds information about
which power conversion unit, 10 or 20, is set as an operation-system unit. Also, as
described above, the determination result indicating the presence or absence of the failure
20 of the power conversion unit 10 and 20 is sent from the unit controller 12 and 22 to the
contactor controller 32, respectively.
[0042] Specifically, upon the operation instruction signal providing instruction for
the start of the power conversion device 1 being supplied to the contactor controller 32
with both of the contactors MC1 and MC2 being in the open state, the contactor
25 controller 32 outputs the contactor control signal S1 that instructs closing of the contactor
MC1 to close the contactor MC1. The contactor controller 32 then switches the
switcher 31 to connect to the operation-system unit, that is, electrically connects the
15
secondary terminals of the power converter 11 to the electric motor 53. The contractor
controller 32 outputs the contactor control signal S1 providing instruction for the opening
of the contactor MC2 to maintain the contactor MC2 open. Then, upon supply of the
operation instruction signal providing instruction for stoppage of the power conversion
5 device 1, the contactor controller 32 opens the closed contactor MC1. As a result, the
contactors MC1 and MC2 are both in the open state.
[0043] The contactor controller 32 opens the contactor MC1 upon receiving from
the unit controller 12 the determination result indicating that the failure of the power
conversion unit 10 occurs in a case where the contactor MC1 is closed and the switcher
10 31 is switched to connect to the operation-system unit. The contactor controller 32 then
switches the switcher 31 to connect to the standby-system unit, that is, electrically
connects the secondary terminals of the power converter 21 to the electric motor 53.
Then, the contactor controller 32 outputs the contactor control signal S1 providing
instruction for the contactor MC2 to close the contactor MC2.
15 [0044] As described above, the sensor 33 includes the input current sensor CT1 that
measures the value of the current flowing in the input busbar B1 and outputs the
measured value, and the input current sensor CT2 that measures the value of the current
flowing in the input busbar B2 and outputs the measured value. The input current
sensor CT1 operates by receiving supply of the electric power from the unit controller 12
20 and sends the measured value to the unit controller 12. The input current sensor CT2
operates by receiving supply of the electric power from the unit controller 22 and sends
the measured value to the unit controller 22. Since the structures of the input current
sensors CT1 and CT2 are the same, the description is given using just the input current
sensor CT1.
25 [0045] The input current sensor CT1 is a current transformer (CT) type of current
sensor. Specifically, as illustrated in FIGS. 2 and 3, the input current sensor CT1
includes a first case 41, a first magnetic core 42, and a first measurement circuit 43 that
16
measures current based on change in magnetic flux occurring in the first magnetic core
42.
[0046] The first case 41 has an annular shape with a through hole 41a in the center
thereof. Here, the annular shape includes a polygonal shape having a through hole in
5 the center and is not limited to a circular ring shape. The first case 41 is made of an
insulator, for example, a synthetic resin. The first magnetic core 42 has an annular
shape with a through hole in the center thereof. Upon current flowing into the input
busbar B1, the magnetic flux of the first magnetic core 42 changes. The first
measurement circuit 43 measures a value of current flowing in the input busbar B1 from
10 the change of magnetic flux of the first magnetic core 42. Then the first measurement
circuit 43 sends a signal indicating the measured value from an unillustrated output
terminal to the unit controller 12.
[0047] The input current sensor CT1 having the above structure is attached to the
input busbar B1 to which insulation is applied, with the input busbar B1 inserted through
15 the through hole 41a in the center of the first case 41. Similarly, the input current sensor
CT2 is attached to the input busbar B2 to which insulation is applied, with the input
busbar B2 inserted through the through hole 41a in the center of the first case 41.
[0048] Next, operation of the power conversion device 1 having the above structure
is described. First, a case where failure does not occur in the power conversion units 10
20 and 20 is described as an example. Upon contact of the current collector 52 with the
overhead line 51 after operation of an upward movement switch for moving the current
collector 52 upward at start of the electric railway vehicle, the current collector 52
receives supply of the electric power from a substation.
[0049] In conjunction with the operation of the upward movement switch, the
25 operation instruction signal providing instruction for startup is supplied to the contactor
controller 32. Upon supply of an open/close instruction signal providing the instruction
for startup, the contactor controller 32 maintains the contactor MC2 in the open state and
17
outputs the contactor control signal S1 providing instruction for closure of the contactor
MC1. As a result, the contactor MC1 is closed and the contactor MC2 is maintained in
the open state. Then the electric power acquired by the current collector 52 from the
substation via the overhead line 51 is supplied to the filter capacitor FC1 via the contactor
5 MC1 and the filter reactor FL1, and charging of the filter capacitor FC1 starts.
[0050] Upon start of operation after startup of the electric railway vehicle, the
running command is input from a driver's cab to the unit controllers 12 and 22. The unit
controllers 12 and 22 acquire values of voltage across the terminals of the filter capacitors
FC1 and FC2 from an unillustrated voltage measurer, respectively. With the contactor
10 MC1 closed and the contactor MC2 opened, only the filter capacitor FC1 is charged.
Upon the value of the voltage across the terminals of the filter capacitor FC1 being equal
to or greater than a threshold and the running command including a powering command,
that is, at the powering time of the electric railway vehicle with the filter capacitor FC1
charged, the unit controller 12 controls the switching elements of the power converter 11
15 to cause the power converter 11 to convert the DC electric power into the three-phase AC
electric power for driving the electric motor 53.
[0051] Specifically, the unit controller 12 calculates a target torque for acquiring a
target acceleration indicated by the powering command. The unit controller 12 also
acquires, from an unillustrated electric motor current measurer, a measured value of the
20 current flowing in the electric motor 53, and calculates an actual torque of the electric
motor 53 from the acquired measured value. Specifically, the unit controller 12
acquires, from the electric motor current measurer that measures values of U-phase,
V-phase, and W-phase current flowing in the electric motor 53, measured values of phase
current flowing in the electric motor 53, and calculates the actual torque of the electric
25 motor 53 from the measured values of the phase current. Then, by sending the
switching control signals S21 to the switching elements of the power converter 11, the
unit controller 12 controls the switching elements to bring the actual torque of the electric
18
motor 53 close to the target torque.
[0052] The unit controller 22 maintains the switching elements of the power
converter 21 turned off since the contactor MC2 is opened and the filter capacitor FC2 is
not charged.
5 [0053] In a case of the running command including the brake command, that is, at
braking time of the electric railway vehicle, the electric motor 53 operates as an electric
generator and supplies the three-phase AC electric power to the power converter 11. In
this case, the unit controller 12 controls the switching elements of the power converter 11
to cause the power converter 11 to convert the three-phase AC electric power into the DC
10 electric power. This enables the power conversion device 1 to supply electric power via
the overhead line 51 to another electric railway vehicle located nearby. As a result, a
regenerative braking force is generated in the electric railway vehicle and the electric
railway vehicle decelerates.
[0054] Next, a case where a failure of the power conversion unit 10 occurs while
15 the unit controller 12 controls the power converter 11 after the contactor MC1 is closed is
used as an example to describe operation of the power conversion device 1 to switch
from the operation-system unit to the standby-system unit.
[0055] For example, a case where input current of the power converter 11 is
excessive in the power conversion unit 10 in a case of the running command including
20 the powering command is used as an example to describe operation of the power
conversion device 1. The unit controller 12 determines that a failure of the power
conversion unit 10 occurs since the measured value of the input current sensor CT1 is
excessive and out of the first current range. Then the unit controller 12 turns off the
switching elements of the power converter 11. The unit controller 12 sends to the unit
25 controller 22 and the contactor controller 32 the determination result indicating that the
failure of the power conversion unit 10 occurs.
[0056] Upon the contactor controller 32 acquiring from the unit controller 12 the
19
determination result that the failure of the power conversion unit 10 occurs in a case
where the contactor MC1 is closed, the contactor controller 32 opens the contactor MC1.
Then the contactor controller 32 controls the switcher 31 to electrically connect the
secondary terminals of the power converter 21 to the electric motor 53. In other words,
5 the switcher 31 switches to connect to the standby-system unit. Then the contactor
controller 32 outputs the contactor control signal S1 providing instruction for closure of
the contactor MC2 to close the contactor MC2.
[0057] Upon closing of the contactor MC2, the electric power acquired by the
current collector 52 from the substation via the overhead line 51 is supplied to the filter
10 capacitor FC2 via the contactor MC2 and the filter reactor FL2, and charging of the filter
capacitor FC2 starts.
[0058] Upon acquiring from the unit controller 12 the determination result
indicating that the failure of the power conversion unit 10 occurs, the unit controller 22
acquires the value of the voltage across the terminals of the filter capacitor FC2 from an
15 unillustrated voltage measurer. Upon the value of the voltage across the terminals of the
filter capacitor FC2 being equal to or greater than a threshold so that the running
command is included in the powering command, that is, at the powering time of the
electric railway vehicle with the filter capacitor FC2 charged, the unit controller 22
controls the switching elements of the power converter 21 to cause the power converter
20 21 to convert the DC electric power into the three-phase AC electric power for driving
the electric motor 53.
[0059] Specifically, the unit controller 22 calculates a target torque for acquiring a
target acceleration indicated by the powering command. The unit controller 22 also
acquires, from an unillustrated electric motor current measurer, a measured value of the
25 current flowing in the electric motor 53, and calculates an actual torque of the electric
motor 53 from the acquired measured value. Specifically, the unit controller 22
acquires, from the electric motor current measurer that measures values of U-phase,
20
V-phase, and W-phase current flowing in the electric motor 53, measured values of phase
current flowing in the electric motor 53, and calculates the actual torque of the electric
motor 53 from the measured values of the phase current. Then, by sending the
switching control signals S22 to the switching elements of the power converter 21, the
5 unit controller 22 controls the switching elements to bring the actual torque of the electric
motor 53 close to the target torque.
[0060] The unit controller 12 maintains the switching elements of the power
converter 11 turned off since the contactor MC1 is opened and the filter capacitor FC1 is
not charged.
10 [0061] Upon acquiring from the unit controller 12 the determination result
indicating that the failure of the power conversion unit 10 occurs in a case of the running
command including the brake command, that is, at braking time of the electric railway
vehicle, the unit controller 22 controls the switching elements of the power converter 21
to cause the power converter 21 to convert the three-phase AC electric power into the DC
15 electric power. Similarly to the above-described example, the contactor controller 32
controls the switcher 31 to electrically connect the secondary terminals of the power
converter 21 to the electric motor 53. This enables the power conversion device 1 to
supply electric power via the overhead line 51 to another electric railway vehicle located
nearby.
20 [0062] In this way, even with the failure of the power conversion unit 10 occurring,
operation of the power conversion unit 20 enables continuous supply of the electric
power to the electric motor 53 to drive the electric railway vehicle and occurrence of
braking force in the electric railway vehicle by consuming the electric power generated in
the electric motor 53.
25 [0063] During the above-described operation of the power conversion device 1, the
unit controllers 12 and 22 determine presence or absence of a failure of each of the power
conversion units 10 and 20 at a determined interval, respectively, and send and receive
21
the determination result. The sending and receiving of the determination report
performed by the power conversion units 10 and 20 are described using FIG. 4.
[0064] As described above, the unit controller 12 determines the presence or
absence of a failure of the power conversion unit 10 based on the measured value of the
5 input current sensor CT1 and whether the contactor MC1 is in the closed state or the open
state (Step Sq1).
[0065] Similarly, the unit controller 22 determines the presence or absence of a
failure of the power conversion unit 20 based on the measured value of the input current
sensor CT2 and whether the contactor MC2 is in the closed state or the open state (Step
10 Sq2).
[0066] Then the unit controller 12 sends text data including the determination result
in step Sq1 via a transmission line TL1 to the unit controller 22 (Step Sq3). For
example, the unit controller 12 uses a transmission control character to transmit the text
data including the determination result in step Sq1 to the unit controller 22 as one block.
15 [0067] The unit controller 22 having received the text data from the unit controller
12 sends the text data including the determination result in step Sq2 via the transmission
line TL1 to the unit controller 12 (step Sq4). The unit controllers 12 and 22 repeat the
above-described processing at a determined interval, for example, at a constant interval.
The unit controllers 12 and 22 can thereby acquire information about the presence or
20 absence of a failure of the respective power conversion units 10 and 20.
[0068] As described above, the power conversion device 1 according to
Embodiment 1 includes the power conversion units 10 and 20, one of which is set as an
operation-system unit and the other one of which is set as a standby-system unit.
Specifically, the main circuit is redundant since the power conversion device 1 includes
25 the contactor MC1, the filter reactor FL1, the filter capacitor FC1, and the power
converter 11 of the power conversion unit 10, as well as the contactor MC2, the filter
reactor FL2, the filter capacitor FC2, and the power converter 21 of the power conversion
22
unit 20. Thus the power conversion device 1 has high redundancy.
[0069] Since the unit controllers 12 and 22 are connected to each other by the
transmission line TL1, the number of wires can be less than a case where the unit
controllers 12 and 22 are connected to each other by hard wiring, thereby reducing wiring
5 work cost.
[0070] Embodiment 2
The sensor 33 has any configuration that can measure at least one of values of
input current and output current of each of the power converters 11 and 21. A power
conversion device 2 according to Embodiment 2 is hereinafter described mainly in terms
10 of points of difference from the power conversion device 1 according to Embodiment 1.
[0071] The sensor 33 included in the power conversion device 2 illustrated in FIG.
5 includes the input current sensor CT1 that measures a value of input current of the
power converter 11, specifically, a value of current flowing in the input busbar B1
connecting the filter reactor FL1 to the power converter 11. The sensor 33 includes the
15 input current sensor CT2 that measures a value of input current of the power converter 21,
specifically, a value of current flowing in the input busbar B2 connecting the filter reactor
FL2 to the power converter 21.
[0072] The input current sensors CT1 and CT2 are both connected to the unit
controller 12, and receives supply of electric power from the unit controller 12 and
20 operates. Then the input current sensors CT1 and CT2 send the measured values of
current to the unit controller 12.
[0073] The unit controller 12 determines presence or absence of a failure of the
power conversion unit 10, similarly to Embodiment 1. The unit controller 12
analog-to-digital (A/D) converts the value of current acquired from the input current
25 sensor CT2 and sends the converted value as text data via the transmission line TL1 to
the unit controller 22. In other words, the unit controller 22 acquires the measured value
of the input current sensor CT2 via the unit controller 12.
23
[0074] The unit controller 22 determines presence or absence of a failure of the
power conversion unit 20 based on the measured value of the input current sensor CT2
acquired from the unit controller 12, similarly to Embodiment 1.
[0075] Specifically, as illustrated in FIG. 6, the unit controller 12 determines the
5 presence or absence of a failure of the power conversion unit 10 based on the measured
value of the input current sensor CT1 and whether the contactor MC1 is in the closed
state or the open state (Step Sq1).
[0076] The unit controller 12 performs A/D conversion of the value of current
acquired from the input current sensor CT2. Then the unit controller 12 sends via the
10 transmission line TL1 to the unit controller 22 the text data including the determination
result in step Sq1 and the measured value of the input current sensor CT2 (step Sq5).
For example, the unit controller 12 uses a transmission control character to transmit to the
unit controller 22 the text data including the determination result in step Sq1 and the
measured value of the input current sensor CT2 by dividing the text data into a plurality
15 of blocks.
[0077] The unit controller 22 having received the text data from the unit controller
12 determines presence or absence of a failure of the power conversion unit 20 based on
the measured value of the input current sensor CT2 and whether the contactor MC2 is in
the closed state or the open state (step Sq2).
20 [0078] Then the unit controller 22 sends via the transmission line TL1 to the unit
controller 12 the text data including the determination result in step Sq2 (step Sq4). The
unit controllers 12 and 22 repeat the above-described processing at a determined interval,
for example, at a constant interval. The unit controllers 12 and 22 can thereby acquire
information about the presence or absence of a failure of the respective power conversion
25 units 10 and 20. The unit controller 22 can also acquire the measured value of the input
current sensor CT2 via the unit controller 12.
[0079] As described above, in the power conversion device 2 according to
24
Embodiment 2, both of the input current sensors CT1 and CT2 are connected to the unit
controller 12. Thus, connecting only the unit controller 12 to each of the input current
sensors CT1 and CT2 is sufficient. In other words, providing the unit controller 22 with
an interface for connection of the input current sensor CT2 is unnecessary. This can
5 achieve simple configuration of the unit controller 22.
[0080] Embodiment 3
The configuration of the sensor 33 is not limited to those of the examples of
Embodiments 1 and 2. The sensor 33 included in a power conversion device 3
according to Embodiment 3 includes an input current sensor CT3 shared by the power
10 conversion units 10 and 20. The power conversion device 3 is described below mainly
in terms of points of difference from the power conversion device 1 according to
Embodiment 1.
[0081] The sensor 33 included in the power conversion device 3 according to
Embodiment 3 illustrated in FIG. 7 includes the input current sensor CT3 that measures a
15 value of input current of the power converter 11 or a value of input current of the power
converter 21. The input current sensor CT3 measures a value of current flowing in the
input busbar B1 connecting the filter reactor FL1 to the power converter 11 or a value of
current flowing in the input busbar B2 connecting the filter reactor FL2 to the power
converter 21. The input current sensor CT3 receives supply of electric power from the
20 unit controller 12 and operates, and sends the measured value to the unit controller 12.
[0082] In the power conversion device 3, one of the power conversion units 10 and
20 is set as an operation-system unit and the other one is set as a standby-system unit.
In other words, during operation of the power conversion device 3, current flows through
either of the input busbar B1 or B2. Thus the value of the input current of the power
25 converter 11 or the value of the input current of the power converter 21 can be measured
by the input current sensor CT3 that is shared by the power conversion units 10 and 20.
[0083] With the contactor MC1 closed, the input current sensor CT3 measures the
25
value of the input current of the power converter 11 of the power conversion unit 10
including the closed contactor MC1. Alternatively, with the contactor MC2 closed, the
input current sensor CT3 measures the value of the input current of the power converter
21 of the power conversion unit 20 including the closed contactor MC2.
5 [0084] The structure of the input current sensor CT3 is the same as the input current
sensor CT1 according to Embodiment 1 except that, as illustrated in FIG. 8, the input
busbars B1 and B2 are inserted through the through hole 41a of the first case 41 included
in the input current sensor CT3. The input current sensor CT3 having the above
structure is attached to at least one of the input busbars B1 and B2 to which insulation is
10 applied, with the input busbars B1 and B2 inserted through the through hole 41a in the
center of the first case 41.
[0085] Upon current flowing into either of the input busbars B1 or B2, the magnetic
flux of the first magnetic core 42 changes. Similarly to Embodiment 1, the first
measurement circuit 43 measures a value of current flowing in either of the input busbar
15 B1 or B2 based on a change in magnetic flux of the first magnetic core 42. Then the
first measurement circuit 43 sends a signal indicating a measured value to the unit
controller 12 from an unillustrated output terminal.
[0086] In a case where the contactor MC1 is in the closed state and the measured
value of the input current sensor CT3 has an absolute value that is out of the first current
20 range, the unit controller 12 determines that the failure of the power conversion unit 10
occurs.
[0087] The unit controller 12 A/D converts the value of current acquired from the
input current sensor CT3 and sends the converted value as text data via the transmission
line TL1 to the unit controller 22. In other words, the unit controller 22 acquires the
25 measured value of the input current sensor CT3 via the unit controller 12.
Communication between the unit controllers 12 and 22 are similar to communication
between the unit controllers 12 and 22 included in the power conversion device 2
26
according to Embodiment 2.
[0088] The unit controller 22 determines presence or absence of a failure of the
power conversion unit 20 based on the measured value of the input current sensor CT3
acquired from the unit controller 12. Specifically, in a case where the contactor MC2 is
5 the closed state and the measured value of the input current sensor CT3 has an absolute
value that is out of the first current range, the unit controller 22 determines that the failure
of the power conversion unit 20 occurs. The measured value of the input current sensor
CT3 acquired by the unit controller 22 from the unit controller 12 with the contactor
MC2 closed can be regarded as a value of the input current of the power converter 21.
10 [0089] As described above, the sensor 33 included in the power conversion device
3 according to Embodiment 3 includes the input current sensor CT3 that is shared by the
power conversion units 10 and 20. In comparison to the case of providing the input
current sensors CT1 and CT2 respectively corresponding to the power conversion unit 10
and 20 as in Embodiments 1 and 2, the configuration of the sensor 33 included in the
15 power conversion device 3 according to Embodiment 3 is simple.
[0090] Embodiment 4
The sensor 33 may measure a value of output current of the power converter 11 or
the power converter 21. The sensor 33 included in a power conversion device 4
according to Embodiment 4 measures values of the input current and the output current of
20 the power converter 11 or values of the input current and the output current of the power
converter 21. The power conversion device 4 is described below mainly in terms of
points of difference from Embodiment 3.
[0091] As illustrated in FIG. 9, the secondary terminals of the switcher 31 included
in the power conversion device 4 according to Embodiment 4 are connected to the
25 electric motor 53 by output busbars B3, B4, and B5 corresponding to the U phase, the V
phase, and the W phase, respectively. In other words, current flowing in the output
busbars B3, B4, and B5 is respectively U-phase, V-phase, and W-phase current.
27
[0092] The sensor 33 included in the power conversion device 4 includes output
current sensors CT4, CT5, and CT6 that measure values of output current of the power
converter 11 or the power converter 21 and output the measured values, in addition to the
configuration of the sensor 33 included in the power conversion device 3 according to
5 Embodiment 3.
[0093] Specifically, the output current sensor CT4 measures a value of current
flowing in the output busbar B3 connecting the switcher 31 to the electric motor 53 and
outputs the measured value. The output current sensor CT5 measures a value of current
flowing in the output busbar B4 connecting the switcher 31 to the electric motor 53 and
10 outputs the measured value. The output current sensor CT6 measures a value of current
flowing in the output busbar B5 connecting the switcher 31 to the electric motor 53 and
outputs the measured value.
[0094] The output current sensors CT4, CT5, and CT6 operate by receiving power
from the unit controller 12 and send the measured values to the unit controller 12. Since
15 the structures of the output current sensors CT4, CT5, and CT6 are the same, description
is given using just the output current sensor CT4.
[0095] The output current sensor CT4 is a CT type of current sensor. Specifically,
as illustrated in FIGS. 10 and 11, the output current sensor CT4 includes a second case 44,
a second magnetic core 45, and a second measurement circuit 46 that measures current
20 based on change in magnetic flux occurring in the second magnetic core 45.
[0096] The second case 44 has an annular shape with a through hole 44a in the
center thereof. Here, the annular shape includes a polygonal shape having a through
hole in the center and is not limited to a circular ring shape. The second case 44 is made
of an insulator, for example, a synthetic resin. The second magnetic core 45 has an
25 annular shape with a through hole in the center thereof. Upon current flowing into the
output busbar B3, the magnetic flux of the second magnetic core 45 changes. The
second measurement circuit 46 measures a value of current flowing in the output busbar
28
B3 from the change of magnetic flux of the second magnetic core 45. Then the second
measurement circuit 46 sends a signal indicating the measured value from an
unillustrated output terminal of the output current sensor CT4 to the unit controller 12.
[0097] The output current sensor CT4 having the above structure is attached to the
5 output busbar B3 to which insulation is applied, with the output busbar B3 inserted
through the through hole 44a in the center of the second case 44. Similarly, the output
current sensor CT5 is attached to the output busbar B4 to which insulation is applied,
with the output busbar B4 inserted through the through hole 44a in the center of the
second case 44. Similarly, the output current sensor CT6 is attached to the output
10 busbar B5 to which insulation is applied, with the output busbar B5 inserted through the
through hole 44a in the center of the second case 44.
[0098] The unit controller 12 determines presence or absence of a failure of the
power conversion unit 10 based on the values of the input current and the output current
of the power converter 11 that is a control target and whether the contactor MC1
15 associated with the power converter 11 is in the closed state or the open state.
Specifically, the presence or absence of a failure of the power conversion unit 10 is
determined based on the measured value of the input current sensor CT3 and the
measured values of the output current sensors CT4, CT5, and CT6 and whether the
contactor MC1 is in the closed state or the open state.
20 [0099] Specifically, in a case where, with the contactor MC1 closed, the measured
value of the input current sensor CT3 has an absolute value that is out of a first current
range or at least one of amplitudes of the measured values acquired from the output
current sensors CT4, CT5, and CT6 is out of a first amplitude range, the unit controller 12
determines that the failure of the power conversion unit 10 occurs. The first amplitude
25 range is determined in accordance with a value that the amplitude of each phase current
of U-phase, V-phase, and W-phase current output by the power converter 11 or the power
converter 21 can have. For example, an upper limit value of the first amplitude range is
29
1.5 times as much as a maximum value of the value that the amplitude of each phase
current of the U-phase, V-phase, and W-phase current can have, and a lower limit value
of the first current range is 0.5 times as much as a minimum value of the value that the
amplitude of each phase current of the U-phase, V-phase, and W-phase current can have.
5 [0100] The unit controller 12 performs A/D conversion of the measured values
acquired from the output current sensors CT4, CT5, and CT6. The unit controller 12
sends via the transmission line TL1 to the unit controller 22 the text data including the
determination result in step Sq1, the measured value of the input current sensor CT3, and
the measured values of the output current sensors CT4, CT5, and CT6, similarly to the
10 processing illustrated in FIG. 6. In other words, the unit controller 22 acquires via the
unit controller 12 the measured value of the input current sensor CT3 and the measured
values of the output current sensors CT4, CT5, and CT6.
[0101] Tue unit controller 22 determines presence or absence of a failure of the
power conversion unit 20 based on the measured value of the input current sensor CT3
15 acquired from the unit controller 12 and the measured values of the output current sensors
CT4, CT5, and CT6 acquired from the unit controller 12. Specifically, in a case where
the contactor MC2 is in the closed state and the measured value of the input current
sensor CT3 has an absolute value that is out of the first current range or at least one of
amplitudes of the measured values of the output current sensors CT4, CT5, and CT6 is
20 out of the first amplitude range, the unit controller 22 determines that the failure of the
power conversion unit 20 occurs.
[0102] The unit controller 12 calculates an actual torque of the electric motor 53
from the measured values of the output current sensors CT4, CT5, and CT6 at the
powering time of the electric railway vehicle with the filter capacitor FC1 charged.
25 Similarly, the unit controller 22 calculates an actual torque of the electric motor 53 from
the measured values of the output current sensors CT4, CT5, and CT6 acquired from the
unit controller 12 at the powering time of the electric railway vehicle with the filter
30
capacitor FC2 charged.
[0103] As described above, in the power conversion device 4 according to
Embodiment 4, the unit controllers 12 and 22 determine the presence or absence of a
failure of the power conversion units 10 and 20, respectively, based on the measured
5 value of the input current sensor CT3 and the measured values of the output current
sensors CT4, CT5, and CT6. Thus the power conversion device 4 can determine the
presence or absence of a failure of the power conversion units 10 and 20 with higher
accuracy than the power conversion devices 1 to 3.
[0104] The unit controller 22 acquires the measured value of the input current
10 sensor CT3 and the measured values of the output current sensors CT4, CT5, and CT6
from the unit controller 12. Thus connecting only the unit controller 12 to the input
current sensor CT3 and the output current sensors CT4, CT5, and CT6 is sufficient. In
other words, providing the unit controller 22 with an interface for connection to the input
current sensor CT3 and the output current sensors CT4, CT5, and CT6 is unnecessary.
15 This can achieve simple configuration of the unit controller 22.
[0105] Embodiment 5
A configuration of the sensor 33 that measures a value of output current of the
power converter 11 or the power converter 21 is not limited to an example of
Embodiment 4. The sensor 33 included in a power conversion device 5 according to
20 Embodiment 5 includes output current sensors CT7, CT8, and CT9 that are shared by the
power conversion units 10 and 20. The power conversion device 5 is described below
mainly in terms of points of difference from that of Embodiment 4.
[0106] As illustrated in FIG. 12, the secondary terminals corresponding to the
respective U phases of the power converters 11 and 21 included in the power conversion
25 device 5 according to Embodiment 5 are connected to the switcher 31 by output busbars
B6 and B7. The secondary terminals corresponding to the respective V phases of the
power converters 11 and 21 are connected to the switcher 31 by output busbars B8 and
31
B9. The secondary terminals corresponding to the respective W phases of the power
converters 11 and 21 are connected to the switcher 31 by output busbars B10 and B11.
[0107] The sensor 33 included in the power conversion device 5 includes the output
current sensors CT7, CT8, and CT9 that measure values of output current of the power
5 converter 11 or the power converter 21 and output the measured value, in addition to the
configuration of the sensor 33 included in the power conversion device 3 according to
Embodiment 3.
[0108] Specifically, the output current sensor CT7 measures a value of current
flowing in the output busbar B6 connecting the power converter 11 to the switcher 31 or
10 a value of current flowing in the output busbar B7 connecting the power converter 21 to
the switcher 31, and outputs the measured value. The output current sensor CT8
measures a value of current flowing in the output busbar B8 connecting the power
converter 11 to the switcher 31 or a value of current flowing in the output busbar B9
connecting the power converter 21 to the switcher 31, and outputs the measured value.
15 The output current sensor CT9 measures a value of current flowing in the output busbar
B10 connecting the power converter 11 to the switcher 31 or a value of current flowing in
the output busbar B11 connecting the power converter 21 to the switcher 31 and outputs
the measured value.
[0109] The output current sensors CT7, CT8, and CT9 operate by receiving supply
20 of electric power from the unit controller 12 and send the measured values to the unit
controller 12.
[0110] In the power conversion device 5, one of the power conversion units 10 and
20 is set as an operation-system unit and the other one is set as a standby-system unit.
In other words, during operation of the power conversion device 5, current flows either in
25 the output busbars B6, B8, and B10 or in the output busbars B7, B9, and B11. Thus the
value of the output current of the power converter 11 or the value of the output current of
the power converter 21 can be measured by the output current sensors CT7, CT8, and
32
CT9 that are shared by the power conversion units 10 and 20.
[0111] With the contactor MC1 closed, the output current sensor CT7 measures a
value of U-phase current output by the power converter 11 of the power conversion unit
10 including the closed contactor MC1. Alternatively, with the contactor MC2 closed,
5 the output current sensor CT7 measures a value of U-phase current output by the power
converter 21 of the power conversion unit 20 including the closed contactor MC2.
[0112] With the contactor MC1 closed, the output current sensor CT8 measures a
value of V-phase current output by the power converter 11 of the power conversion unit
10 including the closed contactor MC1. Alternatively, with the contactor MC2 closed,
10 the output current sensor CT8 measures a value of V-phase current output by the power
converter 21 of the power conversion unit 20 including the closed contactor MC2.
[0113] With the contactor MC1 closed, the output current sensor CT9 measures a
value of W-phase current output by the power converter 11 of the power conversion unit
10 including the closed contactor MC1. Alternatively, with the contactor MC2 closed,
15 the output current sensor CT9 measures a value of W-phase current output by the power
converter 21 of the power conversion unit 20 including the closed contactor MC2.
[0114] Since the structures of the output current sensors CT7, CT8, and CT9 are the
same, the description of just the output current sensor CT7 is given. The structure of the
output current sensor CT7 is the same as that of the output current sensor CT4 according
20 to Embodiment 4 except that, as illustrated in FIG. 13, the output busbars B6 and B7 are
inserted in the through hole 44a of the second case 44 included in the output current
sensor CT7.
[0115] Upon current flowing into either of the output busbars B6 or B7, the
magnetic flux of the second magnetic core 45 changes. Similarly to Embodiment 4, the
25 second measurement circuit 46 measures a value of current flowing in either of the output
busbar B6 or B7 based on a change in magnetic flux of the second magnetic core 45.
Then the second measurement circuit 46 sends a signal indicating a measured value to the
33
unit controller 12 from an unillustrated output terminal.
[0116] The output current sensor CT7 having the above structure is attached to at
least one of the output busbars B6 and B7 to which insulation is applied, with the output
busbars B6 and B7 inserted through the through hole 44a in the center of the second case
5 44. Similarly, the output current sensor CT8 is attached to at least one of the output
busbars B8 and B9 to which insulation is applied, with the output busbars B8 and B9
inserted through the through hole 44a in the center of the second case 44. Similarly, the
output current sensor CT9 is attached to at least one of the output busbars B10 and B11 to
which insulation is applied, with the output busbars B10 and B11 inserted through the
10 through hole 44a in the center of the second case 44.
[0117] The unit controller 12 determines presence or absence of a failure of the
power conversion unit 10 based on the values of the input current and the output current
of the power converter 11 that is a control target and whether the contactor MC1
associated with the power converter 11 is in the closed state or the open state.
15 Specifically, the presence or absence of a failure of the power conversion unit 10 is
determined based on the measured value of the input current sensor CT3 and the
measured values of the output current sensors CT7, CT8, and CT9 and whether the
contactor MC1 is in the closed state or the open state.
[0118] Specifically, in a case where, with the contactor MC1 closed, the measured
20 value of the input current sensor CT3 has an absolute value that is out of the first current
range or at least one of amplitudes of the measured values acquired from the output
current sensors CT7, CT8, and CT9 is out of the first amplitude range, the unit controller
12 determines that a failure of the power conversion unit 10 occurs.
[0119] The unit controller 12 performs A/D conversion of the measured values
25 acquired from the output current sensors CT7, CT8, and CT9. The unit controller 12
sends via the transmission line TL1 to the unit controller 22 the text data including the
determination result in step Sq1, the measured value of the input current sensor CT3, and
34
the measured values of the output current sensors CT7, CT8, and CT9, similarly to the
processing illustrated in FIG. 6. In other words, the unit controller 22 acquires via the
unit controller 12 the measured value of the input current sensor CT3 and the measured
values of the output current sensors CT7, CT8, and CT9.
5 [0120] The unit controller 22 determines presence or absence of a failure of the
power conversion unit 20 based on the measured value of the input current sensor CT3
acquired from the unit controller 12 and the measured values of the output current sensors
CT7, CT8, and CT9 acquired from the unit controller 12. Specifically, in a case where
the contactor MC2 is in the closed state and the measured value of the input current
10 sensor CT3 has an absolute value that is out of the first current range or at least one of
amplitudes of the measured values of the output current sensors CT7, CT8, and CT9 is
out of the first amplitude range, the unit controller 22 determines that the failure of the
power conversion unit 20 occurs. The measured value of the input current sensor CT3
acquired by the unit controller 22 from the unit controller 12 with the contactor MC2
15 closed can be regarded as a value of the input current of the power converter 21. The
measured values of the output current sensors CT7, CT8, and CT9 acquired by the unit
controller 22 from the unit controller 12 with the contactor MC2 closed can be regarded
as values of the output current of the power converter 21.
[0121] The unit controller 12 calculates an actual torque of the electric motor 53
20 from the measured values of the output current sensors CT7, CT8, and CT9 at the
powering time of the electric railway vehicle with the filter capacitor FC1 charged.
Similarly, the unit controller 22 calculates an actual torque of the electric motor 53 from
the measured values of the output current sensors CT7, CT8, and CT9 acquired from the
unit controller 12 at the powering time of the electric railway vehicle with the filter
25 capacitor FC2 charged.
[0122] As described above, the sensor 33 included in the power conversion device
5 according to Embodiment 5 includes the output current sensors CT7, CT8, and CT9
35
that are shared by the power conversion units 10 and 20. The configuration of the
sensor 33 included in the power conversion device 5 according to Embodiment 5 is
simple compared with a case of providing the current sensor in each of the output busbars
B6, B7, B8, B9, B10, and B11.
5 [0123] Embodiments of the present disclosure are not limited to the
above-described examples. The above-described circuit configuration is an example.
The circuit configuration of the power conversion units 10 and 20 can be any circuit that
can convert the electric power supplied from the current collector 52 into electric power
for supply to the electric motor 53.
10 [0124] As an example, in the power conversion unit 10, a charging contactor and a
charging resistor connected in series may be provided in parallel relative to the contactor
MC1. Similarly, in the power conversion unit 20, a charging contactor and a charging
resistor connected in series may be provided in parallel to the contactor MC2.
[0125] In this case, by closing the charging contactor included in the power
15 conversion unit 10 with the contactor MC1 and MC2 opened at start of the power
conversion devices 1 to 5, electric power is to be supplied to the filter capacitor FC1 via
the charging resistor. As a result, occurrence of inrush current at charging of the filter
capacitor FC1 is suppressed. Similarly in a case where the power conversion unit 20 is
set as an operation-system unit, by closing the charging contactor included in the power
20 conversion unit 20 with the contactors MC1 and MC2 opened, electric power is to be
supplied to the filter capacitor FC2 via the charging resistor. As a result, occurrence of
inrush current at charging of the filter capacitor FC2 is suppressed.
[0126] As another example, in the power conversion unit 10, the charging contactor
may be provided in series with the contactor MC1 and the charging resistor may be
25 provided in parallel to the charging contactor. Similarly, in the power conversion unit
10, the charging contactor maybe provided in series with contactor MC1 and charging
resistance.
36
[0127] In this case, by closing the contactor MC1 with the charging contactor
opened at start of the power conversion devices 1 to 5, electric power is to be supplied to
the filter capacitor FC1 via the charging resistor. As a result, occurrence of inrush
current at charging of the filter capacitor FC1 is suppressed. Similarly in the case where
5 the power conversion unit 20 is set as an operation-system unit, by closing the contactor
MC2 with the charging contactor opened, electric power is to be supplied to the filter
capacitor FC2 via the charging resistor. As a result, occurrence of inrush current at
charging of the filter capacitor FC2 is suppressed.
[0128] The power conversion devices 1 to 5 are not limited only to power
10 conversion devices that supply electric power to the electric motor 53 but may be any
power conversion device for which redundancy is needed. The power conversion
devices 1 to 5 are mountable on any vehicle, device, or the like that can supply electric
power to the power conversion devices 1 to 5.
[0129] As an example, the power conversion devices 1 to 5 are mountable on an
15 AC feeding system of electric railway vehicle. In this case, providing a transformer
having a primary terminal connected to a pantograph and a converter that is connected to
secondary terminals of the transformer and converts AC electric power into DC electric
power, and supplying the output of the converter to the power conversion devices 1 to 5,
are sufficient. As another example, the power conversion devices 1 to 5 may be
20 mounted on an electric railway vehicle that acquires electric power via a third rail.
[0130] The number of the power conversion units is not limited to two but can be
any number of three or more. For example, the power conversion devices 1 to 5 may
include three power conversion units and a switcher 31 connected to each of the three
power conversion units and the electric motor 53. In this case, upon supply of the
25 operation instruction signal that provides instruction for the start of the power conversion
device 1, the contactor controller 32 closes the contactor included in the power
conversion unit that is set as an operation-system unit and maintains the contactors
37
included in the other two power conversion units that are set as standby-system units in
the open state. The contactor controller 32 switches the switcher 31 to connect to the
operation-system unit.
[0131] Switching of the power conversion units 10 and 20 is not limited to when a
5 failure occurs. As an example, the power conversion units 10 and 20 to operate may be
switched in a determined cycle. Specifically, the contactor controller 32 may repeatedly
set, in a determined cycle, the power conversion units 10 and 20 from the
operation-system unit to the standby-operation unit or from the standby-system unit to the
operation-system unit. This maintains the same amount of time of use of the power
10 conversion units 10 and 20, thereby suppressing degradation of one of the power
conversion units 10 and 20.
[0132] Which of the power conversion units 10 and 20 is set to be used as an
operation-system unit can be freely selected. For example, the power conversion unit
20 may be set as an operation-system unit and the power conversion unit 10 may be set as
15 a standby-system unit. In this case, upon supply of the operation instruction signal that
provides instruction for the start of the power conversion devices 1 to 5, the contactor
controller 32 may close the contactor MC2 and maintain the contactor MC1 in the open
state. Then the contactor controller 32 may switch the switcher 31 to connect to the
operation-system unit, that is, electrically connect the secondary terminals of the power
20 converter 21 to the electric motor 53.
[0133] Each of the power conversion units 10 and 20 may be connected to an
independent electric motor 53. In this case, the power conversion devices 1 to 5 do not
include the switcher 31, and connecting the secondary terminals of each of the power
converters 11 and 21 to the independent electric motor 53 is sufficient.
25 [0134] A trigger to start the power conversion devices 1 to 5 is not limited to the
operation instruction signal. As an example, the contactor controller 32 may close the
contactor MC1 when the current collector 52 contacts the overhead line 51. Specifically,
38
the contactor controller 32 may acquire a measured voltage value from a voltage
measurer that measures voltage across the positive input terminal 1a and the negative
input terminal 1b that corresponds to the voltage of the overhead line 51, and upon the
voltage value being equal to or greater than a threshold voltage, the contactor controller
5 32 may close the contactor MC1. This threshold voltage may be set in consideration of
a minimum value that the voltage of the overhead line 51 can have.
[0135] The power converter 11 or 21 is not limited to a VVVF inverter. As an
example, the power converter 11 or 21 may be an auxiliary power source that supplies
electric power to a load, such as an illumination device, air conditioner, or the like. The
10 power converter 11 or 21 may also be a DC converter or an AC/DC converter.
[0136] The input current sensors CT1, CT2, and CT3 and the output current sensors
CT4, CT5, CT6, CT7, CT8, and CT9 are not limited to a CT type of sensor. Any type
of current sensor, such as a Hall element type, a Rogowskii coil type, or the like, can be
used as the input current sensors CT1, CT2, and CT3 and the output current sensors CT4,
15 CT5, CT6, CT7, CT8, and CT9.
[0137] In the above embodiments, although the contactor controller 32 is provided
independently of the power conversion units 10 and 20, each of the power conversion
units 10 and 20 may include the contactor controller 32. In this case, the contactor
controller 32 included in the power conversion unit 10 controls the contactor MC1.
20 Similarly, the contactor controller 32 included in the power conversion unit 20 controls
the contactor MC2.
[0138] The unit controller 12 may acquire, from the contactor MC1, a state signal
indicating whether the contactor MC1 is closed or opened. In this case, the unit
controller 12 may determine whether the MC1 is in the closed state or the open state
25 based on the state signal acquired from the contactor MC1. Similarly, the unit controller
22 may acquire, from the contactor MC2, a state signal indicating whether the contactor
MC2 is closed or opened. In this case, the unit controller 22 may determine whether the
39
contactor MC2 is in the closed state or the open state based on the state signal acquired
from the contactor MC2.
[0139] The electric motor 53 is not limited to a three-phase induction electric motor,
but rather may be a synchronous electric motor, a DC electric motor, or the like.
5 [0140] The foregoing describes some example embodiments for explanatory
purposes. Although the foregoing discussion has presented specific embodiments,
persons skilled in the art will recognize that changes may be made in form and detail
without departing from the broader spirit and scope of the invention. Accordingly, the
specification and drawings are to be regarded in an illustrative rather than a restrictive
10 sense. This detailed description, therefore, is not to be taken in a limiting sense, and the
scope of the invention is defined only by the included claims, along with the full range of
equivalents to which such claims are entitled.
Reference Signs List
[0141] 1, 2, 3, 4, 5 Power conversion device
15 1a Positive input terminal
1b Negative input terminal
10, 20 Power conversion unit
11, 21 Power converter
12, 22 Unit controller
20 31 Switcher
32 Contactor controller
33 Sensor
41 First case
41a, 44a Through hole
25 42 First magnetic core
43 First measurement circuit
44 Second case
40
45 Second magnetic core
46 Second measurement circuit
51 Overhead line
52 Current collector
5 53 Electric motor
B1, B2 Input busbar
B3, B4, B5, B6, B7, B8, B9, B10, B11 Output busbar
CT1, CT2, CT3 Input current sensor
CT4, CT5, CT6, CT7, CT8, CT9 Output current sensor
10 FC1, FC2 Filter capacitor
FL1, FL2 Filter reactor
MC1, MC2 Contactor
S1 Contactor control signal
S21, S22 Switching control signal
15 TL1 Transmission line
41
We Claim:
1. A power conversion device, comprising:
a plurality of power conversion units each comprising a power converter that
5 converts electric power supplied from a power source into electric power for supply to a
load and supplies the converted electric power to the load, a contactor that electrically
connects the power converter to the power source or electrically disconnects the power
converter from the power source, and a unit controller that controls switching elements
included in the power converter, the plurality of power conversion units being configured
10 to be connected in common to the power source;
a contactor controller to close or open the contactor included in each of the
plurality of power conversion units; and
a sensor to measure a value of at least one of input current or output current of the
power converter included in each of the plurality of power conversion units, and output
15 the measured value of the at least one of the input current or the output current of the
power converter, wherein
the unit controllers of the plurality of power conversion units are connected to one
another through a transmission line, and
each of the unit controllers determines presence or absence of a failure of the
20 power conversion unit based on the measured value of the at least one of the input current
or the output current of the power converter that is a control target and whether the
contactor associated with the power converter that is the control target is in a closed state
or an open state, and sends a determination result to another unit controller of the unit
controllers.
25
2. The power conversion device according to claim 1, wherein in a case where
the contactor controller closes the contactor included in any of the plurality of power
42
conversion units, the contactor controller maintains the contactor included in another
power conversion unit in the open state.
3. The power conversion device according to claim 2, wherein
5 the unit controller sends the determination result to the contactor controller, and
in a case where the determination result acquired from the unit controller of the
power conversion unit including the closed contactor indicates that a failure of the power
conversion unit occurs, the contactor controller opens the closed contactor and closes the
opened contactor included in any of the other power conversion units of the plurality of
10 power conversion units.
4. The power conversion device according to any one of claims 1 to 3, wherein
the unit controller included in at least one of the plurality of power conversion units
acquires from the sensor the measured value of the at least one of the input current or the
15 output current of the power converter, and sends, to the unit controller included in the
another power conversion unit, the measured value of the at least one of the input current
or the output current of the power converter acquired from the sensor.
5. The power conversion device according to any one of claims 1 to 4, wherein
20 the sensor includes an input current sensor that is shared by the plurality of power
conversion units, and
the shared input current sensor measures a value of the input current of the power
converter included in the power conversion unit with the contactor closed, and outputs
the measured value of the input current of the power converter.
25
6. The power conversion device according to claim 5, wherein the unit
controller included in any of the plurality of power conversion units supplies electric
43
power to the shared input current sensor, acquires the measured value of the input current
from the shared input current sensor, and sends the measured value of the input current
acquired from the shared input current sensor to the unit controller included in the another
power conversion unit.
5
7. The power conversion device according to claim 5 or 6, wherein
the shared input current sensor comprises
a first magnetic core having an annular shape,
a first measurement circuit to measure a value of the input current based on
10 change in magnetic flux occurring in the first magnetic core, and output the measured
value of the input current, and
a first case to accommodate the first magnetic core and the first
measurement circuit, the first case having a through hole in a center thereof,
in each of the plurality of power conversion units, the contactor and the power
15 converter are connected to each other by an input busbar, and
the input busbar that connects the contactor to the power converter of each of the
plurality of power conversion units is inserted in the through hole of the first case.
8. The power conversion device according to any one of claims 1 to 7, wherein
20 the plurality of power conversion units are connected in common to the load.
9. The power conversion device according to claim 8, wherein
the sensor includes an output current sensor that is shared by the plurality of power
conversion units, and
25 the shared output current sensor measures a value of the output current of the
power converter included in the power conversion unit with the contactor closed, and
outputs the measured value of the output current of the power converter.
44
10. The power conversion device according to claim 9, wherein the unit
controller included in any of the plurality of power conversion units supplies electric
power to the shared output current sensor, acquires the measured value of the output
5 current of the power converter from the shared output current sensor, and sends the
measured value of the output current of the power converter acquired from the shared
output current sensor to the unit controller included in the another power conversion unit.
11. The power conversion device according to claim 9 or 10, wherein
10 the shared output current sensor comprises
a second magnetic core having an annular shape,
a second measurement circuit to measure a value of the output current based
on change in magnetic flux occurring in the second magnetic core, and
a second case to accommodate the second magnetic core and the second
15 measurement circuit, the second case having a through hole in a center thereof,
the power converter included in each of the plurality of power conversion units and
the load are connected to each other by an output busbar, and
the output busbar that connects the power converter of each of the plurality of
power conversion units to the load is inserted in the through hole of the second case