1
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
PROPULSION CONTROL APPARATUS AND PROPULSION CONTROL METHOD;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED
AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
5
Field
[0001] The present invention relates to a propulsion
control apparatus to be installed on a railroad car, and a
propulsion control method.
10
Background
[0002] Conventionally, a railroad car rotates wheels to
run by using a plurality of motors. If there is an anomaly
in connection between any of a plurality of motors and an
15 inverter that supplies AC power to the plurality of motors,
such as an open phase or the coming-off of a connector, a
railroad car cannot activate the motor with the connection
anomaly. In such a case, the railroad car runs by using
the other motors normally connected. Therefore, heavier
20 loads are put on the other motors than in normal times, so
that a failure may be caused. Therefore, a railroad car is
required to promptly detect an anomaly in connection
between an inverter and a motor. Patent Literature 1
discloses a technique as follows. When a pulse width
25 modulation (PWM) percentage obtained by division of a
current motor voltage by a motor maximum voltage is greater
than a predetermined value, a train car control apparatus
determines that an anomaly in connection between an
inverter and a motor has occurred.
30
Citation List
Patent Literature
[0003] Patent Literature 1: WO 2015/020009 A
3
Summary
Technical Problem
[0004] In general, when a railroad car is put in a highspeed
state in which the speed of the railroad 5 car is equal
to or greater than a certain speed, the PWM percentage
reaches 100% and does not change. Therefore, the abovedescribed
conventional train car control apparatus has the
following problem. The conventional train car control
10 apparatus can determine the occurrence of a connection
anomaly in a low-speed state in which the speed of a
railroad car does not reach the certain speed, that is, the
PWM percentage does not reach 100%. However, the
conventional train car control apparatus cannot determine
15 the occurrence of a connection anomaly in the high-speed
state in which the speed of the railroad car is equal to or
greater than the certain speed, that is, the PWM percentage
reaches 100%.
[0005] The present invention has been made in view of
20 the above, and an object thereof is to obtain a propulsion
control apparatus capable of detecting an anomaly in
connection between a plurality of motors and a power
conversion unit that supplies AC power to the plurality of
motors, regardless of the running speed of a railroad car.
25
Solution to Problem
[0006] In order to solve the above problem and achieve
the object, a propulsion control apparatus according to the
present invention is to be installed on a train car. The
30 apparatus includes:a power conversion unit to generate
three-phase AC power from DC power or AC power supplied
through a power supply line, the three-phase AC power being
to be supplied to a plurality of motors;a current detection
4
unit to detect current values of the three-phase AC power
to be supplied from the power conversion unit to the
plurality of motors; anda control unit to calculate a slip
frequency from the current values detected by the current
detection unit, calculate a difference 5 between the slip
frequency and a slip frequency command value to be used to
control the plurality of motors, and determine states of
connection between the power conversion unit and the
plurality of motors based on the difference.
10
Advantageous Effects of Invention
[0007] According to the present invention, the
propulsion control apparatus has the effect of enabling
detection of an anomaly in connection between the plurality
15 of motors and the power conversion unit that supplies AC
power to the plurality of motors, regardless of the running
speed of a railroad car.
Brief Description of Drawings
20 [0008] FIG. 1 is a diagram showing a configuration
example of a propulsion control apparatus according to a
first embodiment.
FIG. 2 is a diagram showing an example of a difference
between a slip frequency command value to be acquired by a
25 control unit and an actual slip frequency to be calculated
by the control unit when an anomaly in connection between a
power conversion unit and a motor occurs in the propulsion
control apparatus according to the first embodiment.
FIG. 3 is a flowchart illustrating operation of the
30 propulsion control apparatus according to the first
embodiment.
FIG. 4 is a flowchart illustrating operation of the
control unit included in the propulsion control apparatus
5
according to the first embodiment.
FIG. 5 is a diagram showing an example in which
processing circuitry included in the propulsion control
apparatus according to the first embodiment includes a
processor 5 and a memory.
FIG. 6 is a diagram showing an example in which the
processing circuitry included in the propulsion control
apparatus according to the first embodiment includes
dedicated hardware.
10 FIG. 7 is a flowchart illustrating operation of a
control unit included in a propulsion control apparatus
according to a second embodiment.
Description of Embodiments
15 [0009] Hereinafter, a propulsion control apparatus and a
propulsion control method according to each embodiment of
the present invention will be described in detail with
reference to the drawings. Note that the present invention
is not limited to the embodiments.
20 [0010] First Embodiment.
FIG. 1 is a diagram showing a configuration example of
a propulsion control apparatus 1 according to a first
embodiment of the present invention. The propulsion
control apparatus 1 is an apparatus that is installed on a
25 train 6 and controls the speed of the train 6. The
propulsion control apparatus 1 is connected to an overhead
line 2 via a pantograph 3. Furthermore, the propulsion
control apparatus 1 is connected to a motor 5a via a
connector 4a, and is connected to a motor 5b via a
30 connector 4b. In the following description, the train 6
may be referred to as a railroad car or simply as a train
car.
[0011] The propulsion control apparatus 1 is supplied
with DC power or AC power through the overhead line 2 via
the pantograph 3. In practice, a circuit breaker or the
like is provided between the pantograph 3 and the
propulsion control apparatus 1, but is not illustrated in
the drawing. This is because such a configuration 5 in which
a circuit breaker or the like is provided is a general
configuration, and does not affect the characteristics of
the present embodiment. Note that although a line for
supplying power to the train 6 is illustrated as the
10 overhead line 2 in FIG. 1, a method for supplying power to
the train 6 is not limited thereto, and power may be
supplied to the train 6 by a third rail. In the following
description, the overhead line 2 and the third rail may be
collectively referred to as power supply lines. The
15 propulsion control apparatus 1 converts DC power or AC
power supplied through the overhead line 2 via the
pantograph 3 into three-phase AC power, and supplies the
three-phase AC power to the motors 5a and 5b.
[0012] The connector 4a is a connector capable of
20 simultaneously attaching and detaching wires between the
propulsion control apparatus 1 and the motor 5a. The
connector 4b is a connector capable of simultaneously
attaching and detaching wires between the propulsion
control apparatus 1 and the motor 5b. The motor 5a drives
25 wheels (not illustrated) and the like included in the train
by three-phase AC voltage supplied from the propulsion
control apparatus 1 via the connector 4a. The motor 5b
drives wheels (not illustrated) and the like included in
the train 6 by three-phase AC voltage supplied from the
30 propulsion control apparatus 1 via the connector 4b. The
motors 5a and 5b are, for example, three-phase induction
motors. In the following description, the connectors 4a
and 4b may be referred to as connectors 4 when not
distinguished, and the motors 5a and 5b may be referred to
as motors 5 when not distinguished.
[0013] A configuration of the propulsion control
apparatus 1 will be described in detail. The propulsion
control apparatus 1 includes a power conversion 5 unit 11, a
current detection unit 12, and a control unit 13.
[0014] The power conversion unit 11 generates threephase
AC power to be supplied to a plurality of the motors
5, from DC power or AC power supplied through the overhead
10 line 2. For example, the power conversion unit 11 has the
function of an inverter when DC power is supplied through
the overhead line 2. Meanwhile, the power conversion unit
11 has the functions of a converter and an inverter when AC
power is supplied through the overhead line 2. The power
15 conversion unit 11 includes a switching element (not
illustrated), and generates three-phase AC power to be
supplied to the motors 5a and 5b by turning on and off the
switching element under the control of the control unit 13.
The switching element may be, for example, an insulated
20 gate bipolar transistor (IGBT) or a metal oxide
semiconductor field effect transistor (MOSFET).
[0015] The current detection unit 12 detects current
values of the three-phase AC power to be supplied from the
power conversion unit 11 to the plurality of motors 5. In
25 the example of FIG. 1, the current detection unit 12
detects the current value of each of the u-phase, v-phase,
and w-phase of the three-phase AC power to be supplied from
the power conversion unit 11 to the plurality of motors 5,
but the present invention is not limited thereto. The
30 current detection unit 12 may detect the current values of
two of the u-phase, v-phase, and w-phase of the three-phase
AC power to be supplied from the power conversion unit 11
to the plurality of motors 5. The sum of the respective
current values of these phases is zero. Therefore, if the
current detection unit 12 detects the current values of two
of the u-phase, v-phase, and w-phase, the current value of
the remaining one of these phases can be obtained by
5 calculation.
[0016] The control unit 13 controls operation of the
power conversion unit 11, specifically, the turning on and
off of the switching element included in the power
conversion unit 11 on the basis of a command value for
10 controlling the running of the train 6 and the current
values detected by the current detection unit 12. The
command value is acquired from a train information
management system (not illustrated) or the like. In
addition, the control unit 13 calculates a slip frequency
15 from the current values detected by the current detection
unit 12. The control unit 13 calculates a difference
between the slip frequency and a slip frequency command
value. The slip frequency command value corresponds to the
command value described above, and is used for controlling
20 the plurality of motors 5. The control unit 13 determines
the states of connection between the propulsion control
apparatus 1, that is, the power conversion unit 11 and the
plurality of motors 5 based on the calculated difference.
[0017] A detailed description will be given of operation
25 of the control unit 13 for determining the states of
connection between the power conversion unit 11 and the
plurality of motors 5. The control unit 13 acquires the
slip frequency command value as a command value for
controlling the running of the train 6 from, for example,
30 an external system such as the train information management
system (not illustrated) as described above. The control
unit 13 controls the operation of the power conversion unit
11 such that the slip frequency calculated from the current
values detected by the current detection unit 12 matches
the slip frequency command value. Note that the control
unit 13 may acquire a notch command or the like from the
outside, and obtain the slip frequency command value by
calculation based on the notch command 5 or the like.
Hereinafter, a case where the control unit 13 acquires the
slip frequency command value from the outside will be
described as an example.
[0018] In the example of FIG. 1, the slip frequency
10 command value serves as a command value for driving the two
motors 5a and 5b. The control unit 13 causes the power
conversion unit 11 to supply three-phase AC power for
driving the two motors 5a and 5b, by controlling the
operation of the power conversion unit 11 on the basis of
15 the slip frequency command value. The control unit 13
calculates an actual slip frequency from the current values
detected by the current detection unit 12. The control
unit 13 can grasp the frequency of the three-phase AC power
to be supplied from the power conversion unit 11 to the
20 motors 5 from changes in the current values detected by the
current detection unit 12. The control unit 13 can
calculate the slip frequency by using the frequency of the
three-phase AC power to be supplied from the power
conversion unit 11 to the motors 5, the numbers of poles of
25 the motors 5a and 5b, and the like. The control unit 13
controls the operation of the power conversion unit 11 such
that the slip frequency obtained by calculation matches the
slip frequency command value.
[0019] Here, if there is an anomaly in connection
30 between the power conversion unit 11 and the motor 5a or
the motor 5b, the power conversion unit 11 cannot supply
the three-phase AC power to the motor 5a or the motor 5b.
Examples of the connection anomaly include the coming-off
of the connector 4a between the propulsion control
apparatus 1 and the motor 5a, an open phase of one or more
connection lines between the power conversion unit 11 and
the motor 5a, the coming-off of the connector 4b between
the propulsion control apparatus 1 and the 5 motor 5b, and an
open phase of one or more connection lines between the
power conversion unit 11 and the motor 5b.
[0020] When there occurs an anomaly in connection
between the power conversion unit 11 and the motor 5a or
10 the motor 5b, the slip frequency calculated by the control
unit 13 from the current values detected by the current
detection unit 12 exceeds the slip frequency command value.
FIG. 2 is a diagram showing an example of a difference
between the slip frequency command value to be acquired by
15 the control unit 13 and the actual slip frequency to be
calculated by the control unit 13 when an anomaly in
connection between the power conversion unit 11 and the
motor 5a or the motor 5b occurs in the propulsion control
apparatus 1 according to the first embodiment.In FIG. 2,
20 the horizontal axis represents the speed of the train 6,
that is, a train car speed, and the vertical axis
represents frequency. Furthermore, in FIG. 2, a solid line
represents the slip frequency command value, and a broken
line represents the slip frequency to be obtained when a
25 connection anomaly occurs. Moreover, in FIG. 2, a dotted
line shown in the vertical direction represents a
positional relationship with the train car speed at which
the PWM percentage reaches 100% in Patent Literature 1
described in the background.
30 [0021] As described above, the control unit 13 controls
the operation of the power conversion unit 11 such that the
slip frequency calculated from the current values detected
by the current detection unit 12 matches the slip frequency
command value. Therefore, when there is no anomaly in
connection between the power conversion unit 11 and the
motors 5a and 5b, the actual slip frequency changes in such
a way as to match the slip frequency command value.
Meanwhile, when there occurs an anomaly 5 in connection
between the power conversion unit 11 and the motor 5a or
the motor 5b, the amount of the three-phase AC power to be
supplied from the power conversion unit 11 is not
sufficient to drive the two motors 5. Therefore, the
10 control unit 13 cannot control the operation of the power
conversion unit 11 such that the slip frequency calculated
from the current values detected by the current detection
unit 12 matches the slip frequency command value for
driving the two motors 5. As a result, when there occurs
15 an anomaly in connection between the power conversion unit
11 and the motor 5a or the motor 5b, there arises a
difference between the slip frequency calculated from the
current values detected by the current detection unit 12
and the slip frequency command value.
20 [0022] Therefore, the control unit 13 calculates a
difference between the slip frequency calculated from the
current values detected by the current detection unit 12
and the slip frequency command value. As a result, when
the difference is equal to or greater than a prescribed
25 threshold value, the control unit 13 can determine that an
anomaly in connection between the power conversion unit 11
and the motor 5a or the motor 5b has occurred. The
threshold value to be compared with the calculated
difference is defined as a first threshold value. Note
30 that, in order to prevent erroneous determination due to
the difference suddenly reaching or exceeding the first
threshold value, the control unit 13 may determine that an
anomaly in connection between the power conversion unit 11
and the motor 5a or the motor 5b has occurred, in a case
where a period of duration in which the difference is equal
to or greater than the first threshold value is equal to or
longer than a prescribed period.A threshold value to be
compared with the period of duration 5 in which the
difference is equal to or greater than the first threshold
value is defined as a second threshold value.
[0023] FIG. 3 is a flowchart illustrating operation of
the propulsion control apparatus 1 according to the first
10 embodiment. In the propulsion control apparatus 1, the
power conversion unit 11 generates three-phase AC power to
be supplied to the plurality of motors 5, from DC power or
AC power supplied through the overhead line 2, under the
control of the control unit 13 (step S1). The current
15 detection unit 12 detects current values of the three-phase
AC power to be supplied from the power conversion unit 11
to the plurality of motors 5 (step S2). The control unit
13 determines the states of connection between the power
conversion unit 11 and the plurality of motors 5 by using
20 the current values detected by the current detection unit
12 and the slip frequency command value (step S3).
[0024] FIG. 4 is a flowchart illustrating operation of
the control unit 13 included in the propulsion control
apparatus 1 according to the first embodiment. The
25 flowchart illustrated in FIG. 4 details the operation in
step S3 of the flowchart illustrated in FIG. 3. The
control unit 13 acquires, from the current detection unit
12, the current values detected by the current detection
unit 12 (step S11). The control unit 13 calculates a slip
30 frequency from the current values detected by the current
detection unit 12 (step S12). The control unit 13
calculates a difference between the slip frequency obtained
by calculation and the slip frequency command value to be
used for the operation of the power conversion unit 11
(step S13). The control unit 13 determines whether the
calculated difference is equal to or greater than the first
threshold value (step S14). When the calculated difference
is less than the first threshold value (5 step S14: No), the
control unit 13 returns to the operation of step S11. When
the calculated difference is equal to or greater than the
first threshold value (step S14: Yes), the control unit 13
determines whether a period of duration in which the
10 calculated difference is equal to or greater than the first
threshold value is equal to or greater than the second
threshold value (step S15).
[0025] When the period of duration in which the
calculated difference is equal to or greater than the first
15 threshold value is less than the second threshold value
(step S15: No), the control unit 13 returns to the
operation of step S11. When the period of duration in
which the calculated difference is equal to or greater than
the first threshold value is equal to or greater than the
20 second threshold value (step S15: Yes), the control unit 13
determines that there has occurred an anomaly in connection
between the power conversion unit 11 and the motor 5a or
the motor 5b (step S16).The control unit 13 outputs a
determination result indicating that an anomaly in
25 connection between the power conversion unit 11 and the
motor 5a or the motor 5b has occurred (step S17). For
example, the control unit 13 may output the determination
result to a cab (not illustrated) of the train 6, or may
output the determination result to a ground device (not
30 illustrated). As described above, in the first embodiment,
when the calculated difference is equal to or greater than
the first threshold value, and the period of duration in
which the calculated difference is equal to or greater than
the first threshold value is equal to or greater than the
second threshold value, the control unit 13 determines that
there is an anomaly in connection between the power
conversion unit 11 and at least one of the plurality of
5 motors 5.
[0026] The operation of the control unit 13 for
determining whether an anomaly in connection between the
power conversion unit 11 and the motor 5a or the motor 5b
has occurred has been illustrated in FIG. 1, assuming that
10 the two motors 5 are connected to the propulsion control
apparatus 1. However, this is an example, and the present
invention is not limited thereto. In practice, when the
symbol “N” denotes the number of the motors 5 connected to
the propulsion control apparatus 1, the control unit 13 can
15 determine whether an anomaly in connection between the
power conversion unit 11 and up to N-1 motors 5 has
occurred, by performing the operation of the present
embodiment. Specifically, when the number of the motors 5
connected to the propulsion control apparatus 1 is four,
20 the control unit 13 can determine whether there has
occurred an anomaly in connection between the power
conversion unit 11 and one, two, or three motors 5. In
addition, for example, in a case where an anomaly in
connection of only one of the plurality of motors 5
25 connected to the propulsion control apparatus 1 is
permitted, the first threshold value is appropriately
changed. Specifically, the first threshold value is
increased as compared with a case where an anomaly in
connection of even a single motor 5 is not permitted. As a
30 result, the control unit 13 can determine a connection
anomaly according to the first threshold value. Note that,
in the operation of the present embodiment, when there
occur anomalies in connection between the power conversion
unit 11 and all the motors 5 connected to the propulsion
control apparatus 1, the control unit 13 cannot detect the
connection anomalies.
[0027] Next, a hardware configuration of the propulsion
control apparatus 1 will be described. 5 In the propulsion
control apparatus 1, the power conversion unit 11 is a
power conversion circuit having the function of an inverter
or the functions of a converter and an inverter, as
described above. The current detection unit 12 is a sensor
10 capable of detecting current values of three-phase AC power.
The control unit 13 is implemented by processing circuitry.
The processing circuitry may be a memory and a processor
that executes programs stored in the memory, or may be
dedicated hardware.
15 [0028] FIG. 5 is a diagram showing an example in which
the processing circuitry included in the propulsion control
apparatus 1 according to the first embodiment includes a
processor and a memory. In a case where the processing
circuitry includes a processor 91 and a memory 92, each
20 function of the processing circuitry of the propulsion
control apparatus 1 is implemented by software, firmware,
or a combination of software and firmware. The software or
firmware is described as a program, and stored in the
memory 92. The processor 91 reads and executes the program
25 stored in the memory 92 to implement each function of the
processing circuitry. That is, the processing circuitry
includes the memory 92 for storing programs. As a result
of execution of the programs, the propulsion control
apparatus 1 is caused to perform processing. In addition,
30 it can also be said that these programs cause a computer to
execute a procedure and a method for the propulsion control
apparatus 1.
processing unit (CPU), a processing device, an arithmetic
device, a microprocessor, a microcomputer, a digital signal
processor (DSP), or the like. Furthermore, for example, a
nonvolatile or volatile semiconductor memory such as a
random access memory (RAM), a read only 5 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
disk, a mini disk, or a digital versatile disc (DVD) is
10 applicable to the memory 92.
[0030] FIG. 6 is a diagram showing an example in which
the processing circuitry included in the propulsion control
apparatus 1 according to the first embodiment includes
dedicated hardware. In a case where the processing
15 circuitry includes dedicated hardware, for example, a
single circuit, a composite circuit, a programmed processor,
a parallel-programmed processor, an application specific
integrated circuit (ASIC), a field programmable gate array
(FPGA), or a combination thereof is applicable to
20 processing circuitry 93 illustrated in FIG. 6. The
functions of the propulsion control apparatus 1 may be
separately implemented by the processing circuitry 93, or
may be collectively implemented by the processing circuitry
93.
25 [0031] Note that some of the functions of the propulsion
control apparatus 1 may be implemented by dedicated
hardware, and some of the other functions thereof may be
implemented by software or firmware. Thus, the processing
circuitry can implement each of the above-described
30 functions by means of dedicated hardware, software,
firmware, or a combination thereof.
[0032] As described above, according to the present
embodiment, the control unit 13 calculates a slip frequency
from current values detected by the current detection unit
12 in the propulsion control apparatus 1. The control unit
13 calculates a difference between the calculated slip
frequency and a slip frequency command value. The slip
frequency command value is a command value 5 for controlling
the driving of the motors 5a and 5b and for controlling the
operation of the power conversion unit 11. The control
unit 13 is configured such that when the period of duration
in which the calculated difference is equal to or greater
10 than the first threshold value reaches or exceeds the
second threshold value, the control unit 13 determines that
an anomaly in connection between the propulsion control
apparatus 1, that is, the power conversion unit 11 and the
motor 5a or the motor 5b has occurred.As a result, the
15 control unit 13 can detect an anomaly in connection between
the plurality of motors 5 and the power conversion unit 11
that supplies three-phase AC power to the plurality of
motors 5, regardless of the running speed of the train 6.
In Patent Literature 1 described in the background, the
20 occurrence of a connection anomaly can be determined only
in a range in which train speed is equal to or less than
the speed illustrated in FIG. 2 at which the PWM percentage
reaches 100%. In contrast, the control unit 13 can
determine the occurrence of a connection anomaly even when
25 the speed of the train 6 exceeds the speed at which the PWM
percentage reaches 100%.
[0033] Note that the case where the propulsion control
apparatus 1 is installed on the train 6 which is a railroad
car has been described in the present embodiment, but the
30 present invention is not limited thereto. The propulsion
control apparatus 1 is applicable to an apparatus that
drives a plurality of motors, and the like.
[0034] Second Embodiment.
In the first embodiment, when a period of duration in
which a calculated difference is equal to or greater than
the first threshold value is equal to or greater than the
second threshold value, the control unit 13 determines that
an anomaly in connection between the 5 propulsion control
apparatus 1, that is, the power conversion unit 11 and the
motor 5a or the motor 5b has occurred.In a second
embodiment, even when the period of duration in which the
calculated difference is equal to or greater than the first
10 threshold value is less than the second threshold value,
the control unit 13 determines that an anomaly in
connection between the propulsion control apparatus 1, that
is, the power conversion unit 11 and the motor 5a or the
motor 5b has occurred, in a case where the number of times
15 the calculated difference reaches or exceeds the first
threshold value reaches a prescribed number of
times.Alternatively, even when the period of duration in
which the calculated difference is equal to or greater than
the first threshold value is less than the second threshold
20 value, the control unit 13 determines that there is a sign
of an anomaly in connection between the propulsion control
apparatus 1, that is, the power conversion unit 11 and the
motor 5a or the motor 5b, in a case where the number of
times the calculated difference reaches or exceeds the
25 first threshold value reaches the prescribed number of
times.
[0035] In the second embodiment, the configuration of
the propulsion control apparatus 1 is the same as the
configuration of the propulsion control apparatus 1 in the
30 first embodiment illustrated in FIG. 1.
[0036] FIG. 7 is a flowchart illustrating operation of
the control unit 13 included in the propulsion control
apparatus 1 according to the second embodiment. In the
flowchart illustrated in FIG. 7, operation of step S21 to
step S24 is the same as the operation of step S11 to step
S14 in the flowchart of the first embodiment illustrated in
FIG. 4. When a calculated difference is equal to or
greater than the first threshold value (5 step S24: Yes), the
control unit 13 determines whether a period of duration in
which the calculated difference is equal to or greater than
the first threshold value is equal to or greater than the
second threshold value (step S25). When the period of
10 duration in which the calculated difference is equal to or
greater than the first threshold value is less than the
second threshold value (step S25: No), the control unit 13
determines whether the number of times the calculated
difference reached or exceeded the first threshold value
15 has reached or exceeded a third threshold value (step S26).
When the number of times the calculated difference reached
or exceeded the first threshold value has not reached or
exceeded the third threshold value (step S26: No), the
control unit 13 returns to the operation of step S21.
20 [0037] When the number of times the calculated
difference reached or exceeded the first threshold value
has reached or exceeded the third threshold value (step
S26: Yes), the control unit 13 determines that there has
occurred an anomaly in connection between the power
25 conversion unit 11 and the motor 5a or the motor 5b, or
that there is a sign of an anomaly in connection between
the power conversion unit 11 and the motor 5a or the motor
5b (step S27).When the period of duration in which the
calculated difference is equal to or greater than the first
30 threshold value is equal to or greater than the second
threshold value (step S25: Yes), the control unit 13
determines that there has occurred an anomaly in connection
between the power conversion unit 11 and the motor 5a or
the motor 5b (step S28). The control unit 13 outputs a
determination result of step S27 or step S28 (step S29).
As described above, in the second embodiment, when the
number of times the calculated difference reaches or
exceeds the first threshold value 5 reaches the third
threshold value, and the period of duration in which the
calculated difference is equal to or greater than the first
threshold value is less than the second threshold value,
the control unit 13 determines that there is an anomaly in
10 connection between the power conversion unit 11 and at
least one of the plurality of motors 5, or that there is a
sign of an anomaly in connection between the power
conversion unit 11 and at least one of the plurality of
motors 5.
15 [0038] As described above, according to the present
embodiment, the control unit 13 calculates a slip frequency
from current values detected by the current detection unit
12 in the propulsion control apparatus 1. The control unit
13 calculates a difference between the calculated slip
frequency and a slip frequency command value. The slip
frequency command value is a command value for controlling
the driving of the motors 5a and 5b and for controlling the
operation of the power conversion unit 11. The control
unit 13 is configured such that even when the period of
duration in which the calculated difference is equal to or
greater than the first threshold value is less than the
second threshold value, the control unit 13 determines that
there has occurred an anomaly in connection between the
power conversion unit 11 and the motor 5a or the motor 5b,
30 or that there is a sign of an anomaly in connection between
the power conversion unit 11 and the motor 5a or the motor
5b, in a case where the number of times the calculated
difference reaches or exceeds the first threshold value
reaches the prescribed number of times.As a result, even if
the states of connection between the plurality of motors 5
and the power conversion unit 11 that supplies three-phase
AC power to the plurality of motors 5 have not led to any
connection anomaly thus far, the control 5 unit 13 can detect
a sign of a connection anomaly, that is, a portion where a
connection anomaly is expected to occur in the future.
[0039] The configurations illustrated in the above
embodiments show examples of the subject matter of the
10 present invention, and it is possible to combine the
configurations with another technique that is publicly
known, and is also possible to make omissions and changes
to part of the configurations without departing from the
scope of the present invention.
Reference Signs List
[0040] 1propulsion control apparatus; 2overhead line;
3pantograph; 4a, 4bconnector; 5a, 5bmotor; 6train; 11power
conversion unit; 12current detection unit; 13control unit.
We Claim :
1. A propulsion control apparatus to be installed on a
train car, the apparatus comprising:
a power conversion unit to generate 5 three-phase AC
power from DC power or AC power supplied through a power
supply line, the three-phase AC power being to be supplied
to a plurality of motors;
a current detection unit to detect current values of
the three-phase AC power to be supplied from the power
conversion unit to the plurality of motors; and
a control unit to calculate a slip frequency from the
current values detected by the current detection unit,
calculate a difference between the slip frequency and a
15 slip frequency command value to be used to control the
plurality of motors, and determine states of connection
between the power conversion unit and the plurality of
motors based on the difference.
2. The propulsion control apparatus according to claim 1,
wherein
when the difference is equal to or greater than a
first threshold value, and a period of duration in which
the difference is equal to or greater than the first
25 threshold value is equal to or greater than a second
threshold value, the control unit determines that there is
an anomaly in connection between the power conversion unit
and at least one of the plurality of motors.
3. The propulsion control apparatus according to claim 1,
wherein
when a number of times the difference reaches or
exceeds a first threshold value reaches a third threshold
value, and a period of duration in which the difference is
equal to or greater than the first threshold value is less
than a second threshold value,the control unit determines
that there is an anomaly in connection between the power
conversion unit and at least one of the plurality 5 of motors,
or that there is a sign of an anomaly in connection between
the power conversion unit and at least one of the plurality
of motors.
4. The propulsion control apparatus according to claim 2
or 3, wherein
the control unit outputs a determination result.
5. A propulsion control method for a propulsion control
apparatus to be installed on a train car, the method
comprising:
a first step of causing a power conversion unit to
generate three-phase AC power from DC power or AC power
supplied through a power supply line, the three-phase AC
power being to be supplied to a plurality of motors;
a second step of causing a current detection unit to
detect current values of the three-phase AC power to be
supplied from the power conversion unit to the plurality of
motors; and
a third step of causing a control unit to calculate a
slip frequency from the current values detected by the
current detection unit, calculate a difference between the
slip frequency and a slip frequency command value to be
used to control the plurality of motors, and determine
30 states of connection between the power conversion unit and
the plurality of motors based on the difference.
6. The propulsion control method according to claim 5,
wherein
in the third step, when the difference is equal to or
greater than a first threshold value, and a period of
duration in which the difference is equal to or greater
than the first threshold value is equal 5 to or greater than
a second threshold value, the control unit determines that
there is an anomaly in connection between the power
conversion unit and at least one of the plurality of motors.
7. The propulsion control method according to claim 5,
wherein
in the third step, when a number of times the
difference reaches or exceeds a first threshold value
reaches a third threshold value, and a period of duration
in which the difference is equal to or greater than the
first threshold value is less than a second threshold
value,the control unit determines that there is an anomaly
in connection between the power conversion unit and at
least one of the plurality of motors, or that there is a
sign of an anomaly in connection between the power
conversion unit and at least one of the plurality of motors.
8. The propulsion control method according to claim 6 or
7, wherein
in the third step, the control unit outputs a
determination result.