FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
NOISE REDUCTION DEVICE AND ELECTRIC VEHICLE CONTROL 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
Field
[0001] The present invention relates to a noise
5 reduction device that reduces a noise component current
leaking from a power converter, and to an electric vehicle
control device to be installed in an electric vehicle and
including the noise reduction device.
10 Background
[0002] An electric vehicle control device includes a
power converter that receives power supplied from an
overhead wire and drives a main motor by using the received
power. The power converter internally includes a
15 conversion element. By a switching operation of the
conversion element of the power converter, a return current
including a noise component current flows through a rail
that is a return path to a substation serving as a power
supply. An AC component included in the noise component
20 current may cause malfunction of railway safety equipment
including an existing railway crossing control device and
on-rail detection device. Therefore, there is a case where
it is required to reliably attenuate the AC component
included in the noise component current.
25 [0003] In view of the above technical background, the
following Patent Literature 1 discloses a configuration in
which, in an electric vehicle control device configured to
receive a DC voltage via a filter circuit consisting of a
filter reactor and a filter capacitor, the filter circuit
30 that increases an input impedance with respect to a power
supply frequency of an AC power supply serving as a power
supply of the DC voltage, is connected in parallel to an
existing filter circuit.
3
Citation List
Patent Literature
[0004] Patent Literature 1: Japanese Patent Application
5 Laid-open No. 2006-6002
Summary
Technical Problem
[0005] In the above-described conventional technique, a
10 new filter circuit is added in order to reduce an AC
component included in a noise component current. However,
in the entire filter circuit including the existing filter
circuit and the additional filter circuit, not only the
noise component current desired to be reduced but also an
15 originally necessary DC current component, specifically, a
current of about several hundreds [A] to a thousand [A]
flows. Therefore, an issue arises in which an additional
circuit element must be increased in size, leading to an
increase in vehicle weight and heat generation. For this
20 reason, it is desired to reduce the noise component current
while avoiding an increase in size of the additional
circuit element.
[0006] The present invention has been made in view of
the above, and an object thereof is to obtain a noise
25 reduction device capable of reducing a noise component
current while avoiding an increase in size of an additional
circuit element.
Solution to Problem
30 [0007] In order to solve the above-described problems
and to achieve the object, the present invention is a noise
reduction device that is installed in an electric vehicle
including an inverter and a filter circuit disposed between
4
an overhead wire and the inverter, and that reduces a noise
component current leaking from the inverter to the overhead
wire or a rail. The inverter converts, into AC power to a
load, DC power supplied through a positive bus-bar
5 electrically connected to the overhead wire and through a
negative bus-bar electrically connected to the rail. The
noise reduction device includes a noise reduction unit and
a control unit. The noise reduction unit includes a
capacitor whose negative side is electrically connected to
10 the negative bus-bar via a connection conductor. Further,
the noise reduction unit includes a switching circuit unit
including an upper-arm semiconductor element and a lowerarm semiconductor element connected in series, in which the
upper-arm semiconductor element is connected to a positive
15 side of the capacitor, and the lower-arm semiconductor
element is connected to a negative side of the capacitor.
Furthermore, the noise reduction unit includes a reactor in
which one end is connected to a connection point between
the upper-arm semiconductor element and the lower-arm
20 semiconductor element and another end is electrically
connected to the positive bus-bar. The control unit
controls the switching circuit unit in accordance with a
current flowing through the positive bus-bar or the
negative bus-bar.
25
Advantageous Effects of Invention
[0008] According to the noise reduction device of the
present invention, it is possible to reduce a noise
component current while avoiding an increase in size of an
30 additional circuit element.
Brief Description of Drawings
[0009] FIG. 1 is a diagram illustrating a configuration
5
example of a railway system including a noise reduction
device according to a first embodiment.
FIG. 2 is a diagram illustrating a configuration
example of a control unit in the first embodiment.
5 FIG. 3 is a block diagram illustrating an example of a
hardware configuration that implements functions of an
inverter control unit and the control unit in the first
embodiment.
FIG. 4 is a block diagram illustrating another example
10 of a hardware configuration that implements functions of
the inverter control unit and the control unit in the first
embodiment.
FIG. 5 is a diagram illustrating a configuration
example of a railway system including a noise reduction
15 device according to a second embodiment.
Description of Embodiments
[0010] Hereinafter, a noise reduction device and an
electric vehicle control device according to embodiments of
20 the present invention will be described in detail with
reference to the accompanying drawings. Note that the
present invention is not limited by the following
embodiments.
[0011] First Embodiment.
25 FIG. 1 is a diagram illustrating a configuration
example of a railway system 150 including a noise reduction
device 100 according to a first embodiment. The railway
system 150 includes an overhead wire 1, a current
collection device 2, a switch 3, a power conversion unit 11,
30 a load 8, a wheel 9, and a rail 10. The electric vehicle
control device according to the first embodiment is
configured by the noise reduction device 100 and the power
conversion unit 11.
6
[0012] The railway system 150 is a railway system of a
direct-current overhead wire type. The overhead wire 1 is
connected to a substation (not illustrated). The
substation and the power conversion unit 11 are
5 electrically connected via the current collection device 2,
a positive bus-bar 2a, a negative bus-bar 2b, the switch 3,
the wheel 9, and the rail 10.
[0013] To the overhead wire 1, a DC voltage is supplied.
A rated value of a general DC voltage is in a range of 600
10 V to 3000 V. The current collection device 2 is provided
in an electric vehicle, which is not illustrated. The
current collection device 2 receives DC power supplied from
the overhead wire 1, by contact sliding with the overhead
wire 1. The received DC power is inputted to the switch 3
15 through the positive bus-bar 2a. The switch 3 is a switch
that opens and closes an electrical connection between the
overhead wire 1 and the power conversion unit 11. The
switch 3 may be disposed inside the power conversion unit
11. The switch 3 switches whether or not to supply power
20 to the power conversion unit 11. During a normal operation,
the switch 3 is controlled to an ON state. In addition,
when an inverter 6 is stopped or failed, the switch 3 is
controlled to an OFF state.
[0014] Note that, in FIG. 1, an overhead electrical wire
25 is illustrated as the overhead wire 1, and a pantographshaped current collection device is illustrated as the
current collection device 2, but the present invention is
not limited to these. The overhead wire 1 may be a third
rail that is used in subways and the like. Accordingly,
30 for the current collection device 2, a current collection
device for the third rail may be used.
[0015] The power conversion unit 11 includes a filter
reactor 4a, a filter capacitor 4b disposed at a subsequent
7
stage of the filter reactor 4a, and the inverter 6
including a plurality of semiconductor elements 6a. The
filter reactor 4a is a component in which a conductor is
wound in a coil shape. The filter reactor 4a and the
5 filter capacitor 4b constitute a filter circuit 4. The
filter circuit 4 is disposed between the overhead wire 1
and the inverter 6.
[0016] By a switching operation of the semiconductor
element 6a included in the inverter 6, a return current
10 including a noise component current flows through the rail
10 that serves as a return path to the substation that
serves as power supply. As described above, the AC
component included in the noise component current may cause
malfunction of railroad safety equipment including an
15 existing railway crossing control device and on-rail
detection device. By attenuating the noise component
current included in the return current, the filter circuit
4 reduces an outflow of the AC component included in the
noise component current to the overhead wire 1 and the rail
20 10. Further, in addition to the DC component, an AC
component voltage due to rectification ripples generated in
a rectifier of the substation is superimposed on the DC
voltage outputted from the overhead wire 1. In a case
where this AC component voltage is large, the filter
25 circuit 4 reduces flowing of the noise component current
caused by this AC component voltage to the overhead wire 1
and the rail 10.
[0017] Large electric power is required to drive an
electric vehicle. Therefore, a large current flows through
30 the filter reactor 4a. In order to cope with this, a
cross-sectional area of the conductor of the filter reactor
4a made of aluminum or copper increases. Further, in order
to secure a necessary inductance, the conductor of the
8
filter reactor 4a is configured to be wound many times. In
a case of a general commuter train, the filter reactor 4a
is required to have a current capacity that can withstand a
current of about several hundreds [A] to a thousand [A].
5 Therefore, the filter reactor 4a is a heavy component of
about 500 [kg].
[0018] The inverter 6 included in the electric vehicle
is generally configured by a two-level or three-level
three-phase inverter circuit by using the plurality of
10 semiconductor elements 6a. The inverter 6 is controlled by
an inverter control unit 7. To the inverter 6, a load 8 is
connected.
[0019] In a case where the inverter 6 is an inverter of
a propulsion control device, the load 8 is a main motor for
15 driving of the electric vehicle. The inverter control unit
7 performs driving and braking of the electric vehicle, by
operating the inverter 6 at a variable voltage and a
variable frequency and performing powering control or
regenerative control of the main motor. In a case where
20 the inverter 6 is an inverter of an auxiliary power supply
device, the load 8 is an auxiliary machine including an air
conditioning device, a lighting device, a safety device, a
compressor, a battery, and a control power supply. The
inverter control unit 7 supplies stable power to the load 8
25 by operating the inverter 6 at a constant voltage and a
constant frequency.
[0020] The inverter control unit 7 performs switching
control on the semiconductor element 6a included in the
inverter 6, on the basis of a command from a high-order
30 control system, which is not illustrated. By this control,
the inverter 6 converts DC power held in the filter
capacitor 4b into AC power, to supply to the load 8.
[0021] To the inverter control unit 7, a signal S6
9
outputted from a control unit 90 is inputted. In addition,
the inverter control unit 7 outputs a signal S3 to the
control unit 90 and outputs a signal S7 to the switch 3.
To the switch 3, a signal S4 outputted from the control
5 unit 90 is also inputted. Note that an operation of each
unit by these signals S3, S4, S6, and S7 will be described
later.
[0022] Next, the noise reduction device 100 will be
described. The noise reduction device 100 includes a noise
10 reduction unit 80 and the control unit 90 that controls the
noise reduction unit 80. The noise reduction device 100 is
a device that reduces a noise component current leaking
from the inverter 6 to the overhead wire 1 or the rail 10.
The noise reduction device 100 complements or enhances the
15 function of the filter circuit 4 described above. Although
detailed functions will be described later, the noise
reduction device 100 can effectively reduce an AC component
included in a noise component current that is superimposed
on a return current and flows.
20 [0023] The noise reduction unit 80 includes a capacitor
50, a switching circuit unit 40, a reactor 30, an opening
and closing circuit unit 20, current detectors 60 and 70,
and voltage detectors 81 and 82. In the following
description, the current detector 60 may be referred to as
25 a “first current detector”, and the current detector 70 may
be referred to as a “second current detector”. Note that,
as for the current detector 70 and the voltage detector 82,
existing detectors may be used.
[0024] The switching circuit unit 40 includes an upper30 arm semiconductor element 41 and a lower-arm semiconductor
element 42. The upper-arm semiconductor element 41 and the
lower-arm semiconductor element 42 are connected in series.
The upper-arm semiconductor element 41 is connected to a
10
positive side of the capacitor 50. The lower-arm
semiconductor element 42 is connected to a negative side of
the capacitor 50. The negative side of the capacitor 50 is
connected to the negative bus-bar 2b via a connection
5 conductor 84. One end of the reactor 30 is connected to a
connection point between the upper-arm semiconductor
element 41 and the lower-arm semiconductor element 42.
Another end of the reactor 30 is connected to the positive
bus-bar 2a via the opening and closing circuit unit 20.
10 That is, the another end of the reactor 30 is electrically
connected to the positive bus-bar 2a.
[0025] The control unit 90 controls the switching
circuit unit 40 in accordance with a current IS1 flowing
through the positive bus-bar 2a or the negative bus-bar 2b.
15 [0026] The opening and closing circuit unit 20 is a
switch that opens and closes an electrical connection
between the reactor 30 and the positive bus-bar 2a. The
opening and closing circuit unit 20 includes a circuit unit
in which a circuit including a main switch 21 is mutually
20 connected in parallel to a charging circuit in which a
charging switch 22 and a charging resistor 23 are connected
in series. To the opening and closing circuit unit 20, a
signal S5 outputted from the control unit 90 is inputted.
ON/OFF of the main switch 21 and the charging switch 22 is
25 controlled by the signal S5.
[0027] In a case where the noise reduction device 100 is
activated from a stop state, it is necessary to charge the
capacitor 50. Therefore, first, only the charging switch
22 is controlled to be turned ON. Power from the positive
30 bus-bar 2a flows into the capacitor 50 via the charging
switch 22 and the charging resistor 23, and the capacitor
50 is charged. When the charging of the capacitor 50 is
completed, the main switch 21 is controlled to be turned ON.
11
Note that the main switch 21 and the charging switch 22 are
controlled by the signal S5 outputted from the control unit
90 described later.
[0028] Similarly to the filter reactor 4a, the reactor
5 30 is a component in which a conductor is wound in a coil
shape. Whereas, a current flowing through the reactor 30
is as small as several [A] at maximum. Therefore, the
reactor 30 may have a considerably smaller current capacity
than the filter reactor 4a. For this reason, the reactor
10 30 is a small and lightweight component of about several
[kg].
[0029] The current detector 60 detects a current ICH1
flowing through the reactor 30. A detection value ICH of
the current ICH1 detected by the current detector 60 is
15 inputted to the control unit 90. In the following
description, the detection value ICH may be referred to as
a “first output”. Note that a current flowing through the
reactor 30 and a current flowing through the connection
conductor 84 have the same magnitude and opposite
20 directions. Therefore, the current detector 60 may be
disposed in the connection conductor 84.
[0030] The current detector 70 detects the current IS1
flowing through the positive bus-bar 2a. The current IS1
is also an input current to the filter circuit 4. A
25 detection value IS of the current IS1 detected by the
current detector 70 is inputted to the control unit 90. In
the following description, the detection value IS may be
referred to as a “second output”. Note that a current
flowing through the positive bus-bar 2a and a current
30 flowing through the negative bus-bar 2b have the same
magnitude and opposite directions. Therefore, the current
detector 70 may be disposed in the negative bus-bar 2b.
[0031] An example of the upper-arm semiconductor element
12
41 and the lower-arm semiconductor element 42 is the
illustrated insulated gate bipolar transistor (IGBT)
incorporating an anti-parallel diode, but other switching
elements may be used. Another example of the upper-arm
5 semiconductor element 41 and the lower-arm semiconductor
element 42 is a metal oxide semiconductor field effect
transistor (MOSFET). In addition, not only silicon (Si)
but also silicon carbide (SiC), gallium nitride (GaN),
gallium oxide (Ga2O3), diamond, and the like, which are
10 wide bandgap semiconductors, may be used as a material
constituting the switching element. When the upper-arm
semiconductor element 41 and the lower-arm semiconductor
element 42 are formed with a wide band gap semiconductor
material, it is possible to achieve low loss and high-speed
15 switching.
[0032] To the switching circuit unit 40, signals S1 and
S2 outputted from the control unit 90 are inputted. The
signal S1 is a switching signal for controlling conduction
of the upper-arm semiconductor element 41. The signal S2
20 is a switching signal for controlling conduction of the
lower-arm semiconductor element 42.
[0033] The voltage detector 82 detects an overhead wire
voltage, which is a voltage of the overhead wire 1. A
detection value ES of the overhead wire voltage detected by
25 the voltage detector 82 is inputted to the control unit 90.
[0034] The voltage detector 81 detects a capacitor
voltage, which is a voltage across the capacitor 50. A
detection value ECH of the capacitor voltage detected by
the voltage detector 81 is inputted to the control unit 90.
30 [0035] The capacitor 50 holds a DC voltage higher than
the overhead wire voltage, under control of the control
unit 90. The capacitor 50 functions as a main power supply
of the noise reduction device 100.
13
[0036] Next, a detailed configuration of the control
unit 90 will be described. FIG. 2 is a diagram
illustrating a configuration example of the control unit 90
according to the first embodiment. The control unit 90
5 includes a first control unit 90a, a second control unit
90b, a third control unit 90c, a subtractor 90d, a divider
90e, and a sequence control unit 91.
[0037] To the first control unit 90a, the detection
value IS of the current IS1 detected by the current
10 detector 70 is inputted. In the first control unit 90a, a
DC component of the detection value IS of the current IS1
is cut off, and a signal IAC* mainly including a noise
component is generated. The signal IAC* represents a noise
component flowing through the filter reactor 4a.
15 [0038] To the second control unit 90b, the detection
value ECH of the capacitor voltage detected by the voltage
detector 81 is inputted. In the second control unit 90b, a
deviation DE between the detection value ECH and a signal
ECH*, which is a command value of a capacitor voltage, is
20 subjected to proportional integral (PI) control, and a
controlled value is generated as a signal DEP. The PI
control is arithmetic control with a proportional element
and an integrating element, and is a general arithmetic
method for operating the signal DEP.
25 [0039] The signal DEP is a signal for maintaining the
detection value ECH of the capacitor voltage at the signal
ECH* representing the command value of the capacitor
voltage. In a case where the detection value ECH is larger
than the signal ECH*, the signal DEP is generated such that
30 the capacitor 50 is discharged. In a case where the
detection value ECH is smaller than the signal ECH*, the
signal DEP is generated such that a current in a direction
of charging the capacitor 50 flows.
14
[0040] To the subtractor 90d, the signal IAC* and the
signal DEP are inputted. In the subtractor 90d, the signal
DEP is subtracted from the signal IAC*, and an operated
value thereof is generated as a signal ICH*. The signal
ICH* 5 is a current command signal representing a command
value of a current that should flow through the reactor 30.
[0041] Note that, in the following description, the
signal ICH*, which is an output of the subtractor 90d, may
be referred to as a “first signal”, and the signal IAC*,
10 which is an input of the subtractor 90d, may be referred to
as a “second signal”.
[0042] The divider 90e is inputted with the detection
value ES of the overhead wire voltage and the detection
value ICH of the current ICH1 detected by the current
15 detector 60. In the divider 90e, the detection value ES is
divided by the detection value ECH, and an operated value
thereof is generated as a signal EM. The signal EM is a
signal representing a ratio between a voltage on an input
side and a voltage on an output side in the switching
20 circuit unit 40. The input side is a side of the capacitor
50, and the output side is a side of the reactor 30. The
signal EM takes a value of 0 or more and 1 or less.
[0043] The third control unit 90c is inputted with the
signal ICH* which is an output of the subtractor 90d, the
25 detection value ICH of the current ICH1, the signal EM
which is an output of the divider 90e, and a signal S8
which is an output of the sequence control unit 91
described later. In the third control unit 90c, a
deviation DI between the signal ICH* and the detection
30 value ICH of the current ICH1 is subjected to PI control,
and a controlled value is generated as a signal DIP. The
signal DIP and the signal EM are added, and an operated
value thereof is generated as a signal M*. The signal M*
15
indicates a conduction ratio of the switching circuit unit
40.
[0044] Furthermore, in the third control unit 90c, the
signals S1 and S2 are generated by pulse width modulation
(PWM) control on the signal M* 5 . As described above, the
signal S1 is a switching signal for controlling conduction
of the upper-arm semiconductor element 41, and the signal
S2 is a switching signal for controlling conduction of the
lower-arm semiconductor element 42. A known technique can
10 be used for the PWM control. A triangular wave comparison
method using a triangular wave as a comparison signal, a
sawtooth wave comparison method using a sawtooth wave as a
comparison signal, and the like are generally used.
[0045] Next, the sequence control unit 91 will be
15 described. The sequence control unit 91 receives the
signal S3 outputted from the inverter control unit 7. The
signal S3 is a signal representing an operation command or
a stop command to the noise reduction unit 80. In a case
where the signal S3 is an operation command for instructing
20 an operation of the noise reduction unit 80, the sequence
control unit 91 sets the signal S8 to ON to execute the PWM
control, and sets the signal S5 to ON to control the
opening and closing circuit unit 20 to be turned ON.
[0046] In a case where the signal S3 is a stop command
25 for instructing to stop the operation of the noise
reduction unit 80, the sequence control unit 91 sets the
signal S8 to OFF to stop execution of the PWM control, and
sets the signal S5 to OFF to control the opening and
closing circuit unit 20 to be turned OFF.
30 [0047] Further, in a case where the noise reduction unit
80 has failed, the sequence control unit 91 generates the
signal S6 indicating the failure, and sends to the inverter
control unit 7. In a case where the signal S6 indicates a
16
failure of the noise reduction unit 80, the inverter
control unit 7 stops an operation of the inverter 6 and
controls the switch 3 to be turned OFF by setting the
signal S7 to OFF. Note that the “case where the noise
5 reduction unit 80 has failed” means a case where a failure
has occurred in any of the components of the noise
reduction unit 80.
[0048] Furthermore, in a case where the noise reduction
unit 80 has failed, the sequence control unit 91 generates
10 the signal S4. The signal S4 is a signal for controlling
the switch 3 to be turned OFF, and is outputted to the
switch 3.
[0049] Note that, in the configuration of the first
embodiment, in a case where the noise reduction unit 80 has
15 failed, the signal S4 from the control unit 90 and the
signal S7 from the inverter control unit 7 are outputted to
the switch 3. Therefore, even in a case where not only the
noise reduction unit 80 but also the control unit 90 has
failed, the switch 3 can be reliably controlled to be
20 turned OFF. Accordingly, reliability of the device can be
enhanced.
[0050] Note that, in the following description, the
signals S3 and S7 outputted from the inverter control unit
7 may be referred to as a “third signal” and a “seventh
25 signal”, respectively. In addition, the signals S4, S5, S6,
and S8 outputted from the sequence control unit 91 may be
referred to as a “fourth signal”, a “fifth signal”, a
“sixth signal”, and an “eighth signal”, respectively.
[0051] As described above, the noise reduction unit 80
30 according to the first embodiment includes: the capacitor
50 whose negative side is electrically connected to the
negative bus-bar 2b via the connection conductor 84; and
the switching circuit unit 40 in which the upper-arm
17
semiconductor element 41 is connected to the positive side
of the capacitor 50 and the lower-arm semiconductor element
42 is connected to the negative side of the capacitor 50.
Further, the noise reduction unit 80 includes the reactor
5 30 in which one end is connected to a connection point
between the upper-arm semiconductor element 41 and the
lower-arm semiconductor element 42 and another end is
electrically connected to the positive bus-bar 2a.
Furthermore, the control unit 90 includes the second
10 control unit 90b that performs voltage feedback control
such that the detection value ECH of the capacitor voltage
matches the signal ECH*, which is a command value of the
capacitor voltage. By this voltage feedback control, the
capacitor 50 can obtain necessary power from the overhead
15 wire 1 side via the reactor 30 and the switching circuit
unit 40, and maintain the capacitor voltage at the command
value. This eliminates necessity of a configuration for
maintaining the capacitor voltage by using another charging
device or another power supply device. Therefore, it is
20 possible to reduce a size and a weight of the noise
reduction device 100 and to facilitate handling.
[0052] Further, the control unit 90 also includes the
third control unit 90c that performs current feedback
control such that the detection value ICH of the current
ICH1 flowing through the reactor 30 matches the signal ICH* 25 ,
which is a command value of a current that should flow
through the reactor 30. Due to the current feedback
control, the noise reduction unit 80 can generate a current
having the same magnitude as and an opposite phase to the
30 noise component current included in the current IS1 flowing
through the filter reactor 4a. As a result, noise
component currents at points of the current collection
device 2 and the wheel 9 cancel each other, so that the
18
noise component current can be reduced. In addition, due
to actions of the reactor 30 and the switching circuit unit
40, the overhead wire voltage can be boosted and supplied
to the capacitor 50, so that a voltage higher than the
5 overhead wire voltage can be held. As a result, it is
possible to use the held high-voltage energy without
including an external power supply device or the like, so
that it is possible to effectively reduce an outflow of the
noise component current to the overhead wire 1 and the rail
10 10 while reducing a size and a weight of the noise
reduction unit 80.
[0053] In addition, from the noise reduction unit 80,
only a current having the same magnitude as and the
opposite phase to the noise component current is sent to
15 the positive bus-bar 2a and the negative bus-bar 2b, and an
inflow of a DC current necessary for driving the electric
vehicle is prevented. As a result, a weight of the upperarm semiconductor element 41, the lower-arm semiconductor
element 42, the capacitor 50, and the reactor 30, which are
20 additional circuit elements, can be reduced to about
several tens [kg] in total. In a case where, in order to
obtain an equivalent noise reduction effect, an inductance
value of the filter reactor 4a is increased, a capacitance
of the filter capacitor 4b is increased, or a new filter
25 circuit is added, an increase of about several hundred [kg]
is expected. Therefore, by using the method of the first
embodiment, it is possible to reduce the noise component
current while avoiding an increase in size of the
additional circuit element.
30 [0054] Furthermore, the inverter control unit 7 is
configured to be able to instruct an operation and stop of
the noise reduction device 100. Therefore, the operation
of the inverter 6 and the operation of the noise reduction
19
device 100 can be linked. As a result, because the noise
reduction device 100 operates only when the inverter 6 is
operating, it is possible to eliminate useless operation
and efficiently operate the noise reduction device 100.
5 [0055] In addition, in a case where the noise reduction
unit 80 has failed, the opening and closing circuit unit 20
can be controlled to be turned OFF by the control unit 90.
As a result, it is possible to avoid an outflow of an
unintended noise component current to the overhead wire 1
10 or the rail 10.
[0056] In addition, in a case where the noise reduction
unit 80 has failed, the switch 3 can be controlled to be
turned OFF by the control unit 90 or the inverter control
unit 7, and the operation of the inverter 6 can also be
15 stopped. Therefore, the inverter 6 does not continue the
operation without noticing the failure of the noise
reduction unit 80. As a result, it is possible to avoid an
outflow of an unnecessary noise component current to the
overhead wire 1 or the rail 10.
20 [0057] Note that, as illustrated in FIG. 1, it is
important that the another end of the reactor 30 is
electrically connected to the positive bus-bar 2a at a
connection point between the current collection device 2
and the filter reactor 4a. For example, when the another
25 end of the reactor 30 is connected to the positive bus-bar
2a at a connection point between the filter reactor 4a and
the inverter 6, most of the current ICH1 generated by the
noise reduction device 100 is absorbed by the filter
capacitor 4b. Therefore, the noise component current
30 cannot flow, and a desired effect cannot be exhibited.
[0058] Next, a hardware configuration for implementing
the functions of the inverter control unit 7 and the
control unit 90 in the first embodiment will be described
20
with reference to FIGS. 3 and 4. FIG. 3 is a block diagram
illustrating an example of a hardware configuration that
implements the functions of the inverter control unit 7 and
the control unit 90 in the first embodiment. FIG. 4 is a
5 block diagram illustrating another example of a hardware
configuration that implements the functions of the inverter
control unit 7 and the control unit 90 in the first
embodiment.
[0059] For implementing some or all of the functions of
10 the inverter control unit 7 and the control unit 90 in the
first embodiment, a configuration, as illustrated in FIG. 3,
may be adopted including a processor 300 that performs
arithmetic operation, a memory 302 that stores a program to
be read by the processor 300, and an interface 304 that
15 inputs and outputs signals.
[0060] The processor 300 may be an arithmetic means such
as an arithmetic device, a microprocessor, a microcomputer,
a central processing unit (CPU), or a digital signal
processor (DSP). Further, examples of the memory 302 can
20 include 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
25 disk, a mini disk, and a digital versatile disc (DVD).
[0061] The memory 302 stores a program for executing the
functions of the inverter control unit 7 and the control
unit 90 in the first embodiment. The processor 300
exchanges necessary information via the interface 304, the
30 processor 300 executes a program stored in the memory 302,
and the processor 300 refers to a table stored in the
memory 302, thereby the above-described processing can be
performed. An operation result by the processor 300 can be
21
stored in the memory 302.
[0062] In addition, for implementing some of the
functions of the inverter control unit 7 and the control
unit 90 in the first embodiment, a processing circuitry 303
5 illustrated in FIG. 4 can also be used. The processing
circuitry 303 corresponds to a single circuit, a composite
circuit, an application specific integrated circuit (ASIC),
a field-programmable gate array (FPGA), or a combination of
these. Information inputted to the processing circuitry
10 303 and information outputted from the processing circuitry
303 each can be obtained via the interface 304.
[0063] Note that some of the processing in the inverter
control unit 7 and the control unit 90 may be performed by
the processing circuitry 303, and processing that is not
15 performed by the processing circuitry 303 may be performed
by the processor 300 and the memory 302.
[0064] Second Embodiment.
FIG. 5 is a diagram illustrating a configuration
example of a railway system 150A including a noise
20 reduction device 100A according to a second embodiment. In
the railway system 150A illustrated in FIG. 5, with respect
to the configuration of the railway system 150 illustrated
in FIG. 1, the noise reduction device 100 is replaced with
the noise reduction device 100A, and the switch 3 is
25 replaced with a charging circuit unit 3A. Furthermore, in
the noise reduction device 100A, the opening and closing
circuit unit 20 is removed in the configuration of the
noise reduction device 100 illustrated in FIG. 1. In FIG.
5, the another end of the reactor 30 is changed to be
30 connected to a connection point between the charging
circuit unit 3A and the filter reactor 4a on the positive
bus-bar 2a. Further, the signals S4, S5, and S7 are
changed to be outputted to the charging circuit unit 3A not
22
to the switch 3. Other configurations are identical or
equivalent to those in FIG. 1. The identical or equivalent
configuration units are denoted by the same reference
numerals, and a redundant description is omitted.
5 [0065] In the first embodiment, because the switch 3 and
the opening and closing circuit unit 20 are installed for
the purpose of opening and closing the circuit, they are
not essential parts of the present invention. In addition,
a general electric vehicle is provided with a charging
10 circuit for initial charging of the filter capacitor 4b
having a large capacity. The charging circuit unit 3A of
FIG. 5 corresponds to this charging circuit.
[0066] Similarly to the opening and closing circuit unit
20, the charging circuit unit 3A includes a circuit unit in
15 which a circuit including a main switch 3A1 is mutually
connected in parallel to a charging circuit in which a
charging switch 3A2 and a charging resistor 3A3 are
connected in series. In the charging circuit unit 3A,
ON/OFF of the main switch 3A1 and the charging switch 3A2
20 is controlled by the signals S4 and S5 outputted from the
control unit 90 and the signal S7 outputted from the
inverter control unit 7. Note that a configuration and an
operation of the control unit 90 are equivalent to those of
the first embodiment, and a description thereof will be
25 omitted here.
[0067] Note that the configuration illustrated in the
above embodiment illustrates one example of the contents of
the present invention and can be combined with another
known technique, and it is also possible to omit and change
30 a part of the configuration without departing from the
subject matter of the present invention.
[0068] For example, in FIG. 1, the control unit 90 and
the inverter control unit 7 are described as separate
23
components, but the present invention is not limited to
this. Both the control units may be integrated into one
control unit.
[0069] Further, the noise reduction device 100 has been
5 described as a device that is internally included in the
electric vehicle control device, but the present invention
is not limited to this. The noise reduction device 100 and
the power conversion unit 11 only need to be electrically
connected, and the noise reduction device 100 may be
10 configured as a device outside the electric vehicle control
device.
[0070] Further, in the present specification, the
contents of the invention are described in consideration of
application to the electric vehicle control device, but the
15 application field is not limited to this, and it goes
without saying that the invention can be applied to various
related fields.
Reference Signs List
20 [0071] 1 overhead wire; 2 current collection device;
2a positive bus-bar; 2b negative bus-bar; 3 switch; 3A
charging circuit unit; 3A1 main switch; 3A2 charging
switch; 3A3 charging resistor; 4 filter circuit; 4a
filter reactor; 4b filter capacitor; 6 inverter; 6a
25 semiconductor element; 7 inverter control unit; 8 load; 9
wheel; 10 rail; 11 power conversion unit; 20 opening and
closing circuit unit; 21 main switch; 22 charging switch;
23 charging resistor; 30 reactor; 40 switching circuit
unit; 41 upper-arm semiconductor element; 42 lower-arm
30 semiconductor element; 50 capacitor; 60, 70 current
detector; 80 noise reduction unit; 81, 82 voltage
detector; 84 connection conductor; 90 control unit; 90a
first control unit; 90b second control unit; 90c third
24
control unit; 90d subtractor; 90e divider; 91 sequence
control unit; 100, 100A noise reduction device; 150, 150A
railway system; 300 processor; 302 memory; 303 processing
circuitry; 304 interface.
5
25
We Claim:
1. A noise reduction device that is installed in an
5 electric vehicle and is to reduce a noise component current
leaking from an inverter to an overhead wire or a rail, the
electric vehicle including: the inverter to convert, into
alternating current power to a load, direct current (DC)
power supplied through a positive bus-bar electrically
10 connected to the overhead wire and through a negative busbar electrically connected to the rail; and a filter
circuit disposed between the overhead wire and the inverter,
the noise reduction device comprising:
a noise reduction unit including
15 a capacitor whose negative side is electrically
connected to the negative bus-bar via a connection
conductor,
a switching circuit unit including an upper-arm
semiconductor element and a lower-arm semiconductor element
20 connected in series, the upper-arm semiconductor element
being connected to a positive side of the capacitor, the
lower-arm semiconductor element being connected to a
negative side of the capacitor, and
a reactor in which one end is connected to a
25 connection point between the upper-arm semiconductor
element and the lower-arm semiconductor element and another
end is electrically connected to the positive bus-bar; and
a control unit to control the switching circuit unit
in accordance with a current flowing through the positive
30 bus-bar or the negative bus-bar.
2. The noise reduction device according to claim 1,
wherein
26
in the capacitor, a voltage higher than a voltage of
the overhead wire is held.
3. The noise reduction device according to claim 1 or 2,
5 comprising:
a first current detector to detect a current flowing
through the reactor or the connection conductor; and
a second current detector to detect a current flowing
through the positive bus-bar or the negative bus-bar,
10 wherein
the control unit controls the switching circuit unit
in such a way that a first output that is an output of the
first current detector matches a first signal generated
based on a second output that is an output of the second
15 current detector.
4. The noise reduction device according to claim 3,
wherein
the second output is inputted to the control unit, and
20 the first signal is generated based on a second signal
obtained by removing a DC component included in the second
output.
5. The noise reduction device according to any one of
25 claims 1 to 4, wherein
the electric vehicle includes an inverter control unit
to control an operation of the inverter,
the control unit is configured to be inputted with a
third signal instructing an operation of the noise
30 reduction unit from the inverter control unit, and
switching control is performed on the upper-arm
semiconductor element and the lower-arm semiconductor
element in a case where an operation of the switching
27
circuit unit is instructed by the third signal.
6. The noise reduction device according to any one of
claims 1 to 5, wherein
5 the electric vehicle includes a switch to open and
close an electrical connection between the overhead wire
and the inverter, at a preceding stage of the filter
circuit, and
in a case where a failure occurs in any of components
10 of the noise reduction unit, the control unit generates a
fourth signal to turn OFF the switch and outputs the fourth
signal to the switch.
7. The noise reduction device according to any one of
15 claims 1 to 6, comprising:
an opening and closing circuit unit to open and close
an electrical connection between the reactor and the
positive bus-bar, wherein
in a case where a failure occurs in any of the
20 components of the noise reduction unit, the control unit
generates a fifth signal to control the opening and closing
circuit unit to be turned OFF and outputs the fifth signal
to the opening and closing circuit unit.
25 8. The noise reduction device according to claim 7,
wherein the opening and closing circuit unit is installed
in the noise reduction device.
9. An electric vehicle control device comprising: the
30 noise reduction device according to claim 8; and a power
conversion unit installed with the inverter, the filter
circuit, and an inverter control unit to control an
operation of the inverter, wherein
28
the electric vehicle includes a switch to open and
close an electrical connection between the overhead wire
and the inverter, at a preceding stage of the filter
circuit,
5 the control unit generates a sixth signal including
information on whether or not a failure has occurred in the
noise reduction unit and outputs the sixth signal to the
inverter control unit, and
in a case where the sixth signal indicates a failure
10 of the noise reduction unit, the inverter control unit
generates a seventh signal to turn OFF the switch and
outputs the seventh signal to the switch.
10. An electric vehicle control device comprising: the
15 noise reduction device according to claim 6; and a power
conversion unit installed with the inverter, the filter
circuit, and an inverter control unit to control an
operation of the inverter, wherein
the filter circuit includes a filter capacitor,
20 the electric vehicle includes a charging circuit unit
to charge the filter capacitor, and
in a case where a failure occurs in any of components
of the noise reduction unit, the control unit generates a
fifth signal to control the charging circuit unit to be
25 turned OFF and outputs the fifth signal to the charging
circuit unit.
11. An electric vehicle control device comprising: the
noise reduction device according to claim 6; and a power
30 conversion unit installed with the inverter, the filter
circuit, and an inverter control unit to control an
operation of the inverter, wherein
the filter circuit includes a filter capacitor,
29
the electric vehicle includes a charging circuit unit
to charge the filter capacitor,
the control unit generates a sixth signal including
information on whether or not a failure has occurred in the
5 noise reduction unit and outputs the sixth signal to the
inverter control unit, and
in a case where the sixth signal indicates a failure
of the noise reduction unit, the inverter control unit
generates a seventh signal to turn OFF the charging circuit
10 unit and outputs the seventh signal to the charging circuit
unit.