FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
DETERIORATION DISCRIMINATING DEVICE AND DETERIORATION
DISCRIMINATING 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 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 deterioration determining device and a
deterioration determining method.
5 Background Art
[0002] An electric motor includes a rotor including a rotor core and rotor conductors
placed in slots in the rotor core or permanent magnets, and a stator including a stator core and
stator coils placed in slots in the stator core. The electric motor further includes an insulating
member that insulates the stator core from the stator coils. A deteriorating insulating member
10 may cause, for example, a short circuit inside the electric motor or a ground fault to the outside
of the electric motor. The insulating member is thus preferably checked regularly for the
degree of deterioration.
[0003] The electric motor mounted on a railway vehicle is large and is installed on a
bogie supporting the vehicle body. This complicates maintenance including, for example,
15 removing the electric motor from the bogie and disassembling the electric motor. Thus, the
degree of deterioration of the insulating member cannot be easily checked by frequently
removing the electric motor from the bogie and the insulating member from the electric motor.
The degree of deterioration of the insulating member is thus preferably determined without
removing the electric motor from the bogie and disassembling the electric motor. Patent
20 Literature 1 describes an example device that determines the degree of deterioration of the
insulating member.
Citation List
Patent Literature
[0004] Patent Literature 1: Unexamined Japanese Patent Application Publication No.
25 2014-25753
3
Summary of Invention
Technical Problem
[0005] A deterioration diagnostic device described in Patent Literature 1 measures the
temperature of the coils in the electric motor and converts the operation time of the electric motor
5 at the measured actual temperature to the operation time of the electric motor at a reference
temperature. More specifically, the slope of an Arrhenius plot at the actual temperature is used
as the same slope as the Arrhenius plot at the reference temperature to convert the operation
time of the electric motor at the actual temperature to the operation time of the electric motor at
the reference temperature. The deterioration diagnostic device determines whether the coils
10 have insulation deterioration based on comparison between an integrated value of the converted
operation time and the service life span of the coils at the reference temperature.
[0006] When activation energy in an Arrhenius equation representing the relationship
between the temperature and the service life of the insulating member changes with temperature,
the slope of the Arrhenius plot varies at different temperatures. When the slope of the
15 Arrhenius plot changes with temperature, a greater error may occur in converting the operation
time, reducing the accuracy of deterioration diagnosis performed by the deterioration diagnostic
device described in Patent Literature 1. The same applies to determining the degrees of
deterioration of insulating members covering various conductors, in addition to the insulating
member included in the electric motor.
20 [0007] Under such circumstances, an objective of the present disclosure is to provide a
deterioration determining device and a deterioration determining method that can accurately
determine the degree of deterioration of an insulating member covering a conductor.
Solution to Problem
[0008] To achieve the above objective, a deterioration determining device according to
25 an aspect of the present disclosure includes a temperature acquirer, a damage level determiner,
and a determiner. The temperature acquirer acquires a temperature of an insulating member
covering a conductor. The damage level determiner determines, for each target period, a
4
damage level based on the temperature of the insulating member acquired by the temperature
acquirer and on a relationship between a temperature and a service life of the insulating member.
The service life is a time period for which the insulating member is usable. The damage level
indicates an elapsed time within the service life corresponding to the temperature of the
5 insulating member acquired by the temperature acquirer. The determiner determines a degree
of deterioration of the insulating member based on the damage level determined for each target
period.
Advantageous Effects of Invention
[0009] The deterioration determining device according to the above aspect of the present
10 disclosure can accurately determine the degree of deterioration of the insulating member by
determining the degree of deterioration of the insulating member based on the damage level
indicating the elapsed time within the service life corresponding to the temperature of the
insulating member.
Brief Description of Drawings
15 [0010] FIG. 1 is a block diagram of a deterioration determining device according to
Embodiment 1;
FIG. 2 illustrates a hardware configuration of the deterioration determining device
according to Embodiment 1;
FIG. 3 is a flowchart of an example operation of deterioration degree determination
20 performed by the deterioration determining device according to Embodiment 1;
FIG. 4 is illustrates an example relationship between the temperature and the service life
of an insulating member in Embodiment 1;
FIG. 5 is a block diagram of a deterioration determining device according to
Embodiment 2;
25 FIG. 6 is a flowchart of an example operation of deterioration degree determination
performed by the deterioration determining device according to Embodiment 2;
FIG. 7 is a block diagram of a deterioration determining device according to a first
5
modification of the embodiment;
FIG. 8 is a flowchart of another example operation of deterioration degree determination
performed by the deterioration determining device according to the embodiment.
FIG. 9 is a block diagram of a deterioration determining device according to a second
5 modification of the embodiment; and
FIG. 10 illustrates a hardware configuration of a deterioration determining device
according to a modification of the embodiment.
Description of Embodiments
[0011] A deterioration determining device and a deterioration determining method
10 according to embodiments of the present disclosure are described in detail below with reference
to the drawings. Components identical or corresponding to each other are provided with the
same reference sign in the drawings..
[0012] Embodiment 1
An example of a device including an insulating member covering a conductor is an
15 electric motor mounted on a railway vehicle and drivable with power to generate propulsion for
the railway vehicle. A deterioration determining device to determine the degree of
deterioration of the insulating member included in the electric motor is described in
Embodiment 1. Determining the degree of deterioration of the insulating member includes
determining whether the insulating member hasreached the end of the service life or not, and
20 determining whether the insulating member is approaching the end of the service life or not.
[0013] As illustrated in FIG. 1, an electric motor 91 as a target of deterioration
determination is, for example, a three-phase induction motor drivable with three-phase
alternating current (AC) power from a power converter 11 to generate propulsion for a
railway vehicle.
25 [0014] Although the detailed structure of the electric motor 91 is not illustrated, the
electric motor 91 includes a shaft supported in a rotatable manner, a rotor including a rotor core
and rotor conductors placed in slots in the outer circumferential surface of the rotor core or
6
permanent magnets, and a stator including a stator core and stator coils placed in slots in the
inner circumferential surface of the stator core. The electric motor 91 further includes an
insulating member covering the stator coils that are conductors. The insulating member
insulates the stator core from the stator coils and insulates the adjacent stator coils from one
5 another. The stator is impregnated with insulating varnish as an example insulating member
to cover the stator coils with the insulating member.
[0015] The electric motor 91 is installed on a bogie supporting the vehicle body of
the railway vehicle. When the electric motor 91 operates on power from the power
converter 11, the shaft of the electric motor 91 rotates, and the rotational force of the shaft
10 is transmitted to an axle through a coupling and a gear device. As the axle rotates, wheels
attached to both ends of the axle rotate to generate the propulsion for the railway vehicle.
[0016] The power converter 11 that supplies power to the electric motor 91 is, for
example, a direct current (DC)-three-phase converter mounted on the railway vehicle using a
DC feeder to convert DC power supplied from a power source to three-phase AC power and
15 supply the three-phase AC power to a load. The power converter 11 includes an input terminal
11a connected to the power source and an input terminal 11b grounded. The power converter
11 further includes a power conversion circuit 12 that converts DC power supplied from the
power source to three-phase AC power and supplies the three-phase AC power to the electric
motor 91, a power conversion circuit controller 13 that controls the power conversion circuit 12,
20 a voltage detection circuit 14 that measures phase voltages output from the power conversion
circuit 12, and a current detection circuit 15 that measures phase currents output from the power
conversion circuit 12. The power converter 11 further includes a reactor L1 and a capacitor C1
connected in series between the input terminals 11a and 11b. The power converter 11 with the
above structure is installed under the floor of the vehicle body of the railway vehicle.
25 [0017] The input terminal 11a is electrically connected through a device such as a
contactor or a breaker that is not illustrated to the power source, more specifically, to a current
collector that receives power supplied from an electrical substation through a power line. For
7
example, the current collector is a pantograph that receives power through an overhead line
being an example power line, or a current collector shoe that receives power through a third rail
being an example power line. The input terminal 11b is grounded through, for example, a
ground ring, a ground brush, or a wheel that is not illustrated.
5 [0018] The power conversion circuit 12 includes, for example, an inverter that outputs
AC power with variable effective voltage and frequency. The power conversion circuit 12
includes multiple switching elements. The switching operations of the switching elements are
controlled by the power conversion circuit controller 13. Each switching element includes, for
example, an insulated-gate bipolar transistor (IGBT) or a wide bandgap semiconductor formed
10 from, for example, silicon carbide (SiC), gallium nitride (GaN), or diamond.
[0019] The power conversion circuit controller 13 receives an operation command S1
from a driver’s cab that is not illustrated. The operation command S1 is a command
corresponding to an operation performed by an operator on a master controller installed in the
driver’s cab. More specifically, the operation command S1 is any of a powering command for
15 accelerating the railway vehicle, a braking command for decelerating the railway vehicle, or a
coasting command for coasting the railway vehicle. The coasting command indicates a state
with neither the powering command nor the braking command being input. The power
conversion circuit controller 13 generates and outputs power conversion control signals S2 that
control the switching elements in the power conversion circuit 12 based on the operation
20 command S1. Each of the power conversion control signals S2 is, for example, a pulse-width
modulation (PWM) signal.
[0020] The voltage detection circuit 14 includes a voltage transformer (VT) electrically
connected to a busbar that electrically connects the power conversion circuit 12 and the electric
motor 91, and measures phase voltages output from the power conversion circuit 12, more
25 specifically, the values of U-, V-, and W-phase voltages. The voltage detection circuit 14
transmits the measurement values of the phase voltages to the deterioration determining device
21.
8
[0021] The current detection circuit 15 includes an electric circuit between the power
conversion circuit 12 and the electric motor 91, or for example, a current transformer (CT)
attached to the busbar that electrically connects the power conversion circuit 12 and the electric
motor 91, and measures phase currents output from the power conversion circuit 12, more
5 specifically, the values of U-, V-, and W-phase currents. The current detection circuit 15
transmits the measurement values of the phase currents to the power conversion circuit
controller 13 and the deterioration determining device 21.
[0022] The reactor L1 has one end connected to the input terminal 11a. The reactor L1
has the other end connected to a primary terminal of the power conversion circuit 12. The
10 capacitor C1 has one end connected to the connecting point between the other end of the reactor
L1 and the primary terminal of the power conversion circuit 12. The capacitor C1 has the other
end connected to the connecting point between the input terminal 11b and the primary terminal
of the power conversion circuit 12. The reactor L1 and the capacitor C1 form an LC filter that
reduces harmonic components generated by the switching operations in the power conversion
15 circuit 12.
[0023] The deterioration determining device 21 that determines the degree of
deterioration of the insulating member included in the electric motor 91 described above
includes a temperature acquirer 22 that acquires the temperature of the insulating member
covering the stator coils included in the electric motor 91, a damage level determiner 23 that
20 determines a damage level as an indicator of an elapsed time within the service life of the
insulating member corresponding to the temperature, and a determiner 24 that determines the
degree of deterioration of the insulating member based on the damage level. The deterioration
determining device 21 is installed at any position on the railway vehicle, such as under the floor
of the vehicle body.
25 [0024] The deterioration determining device 21 with the above structure determines the
degree of deterioration of the insulating member for each target period that is defined as
appropriate, and transmits the determination result about the degree of deterioration of the
9
insulating member to a destination 31. The target period is sufficiently shorter than the thermal
time constant of the conductor covered with the insulating member as a target of determination
performed by the deterioration determining device 21, and is, for example, 1 to 5 seconds
inclusive. More specifically, the deterioration determining device 21 determinesthe degree of
5 deterioration of the insulating member for each target period after the first use of the conductor.
The destination 31 is, for example, a display installed in the driver’s cab.
[0025] The temperature acquirer 22 estimates a resistance value of the conductor from
the current flowing through the conductor and from the potential of the conductor, estimates the
temperature of the conductor from the estimated resistance value, and uses the estimated
10 temperature of the conductor as the temperature of the insulating member. In Embodiment 1,
the temperature acquirer 22 calculates the coil resistance value of the stator coils that are
conductors, based on the measurement values of the phase voltages received from the voltage
detection circuit 14 and the measurement values of the phase currents received from the current
detection circuit 15. The coil resistance value positively correlates with the temperature of the
15 stator coils. The temperature acquirer 22 thus estimates the temperature of the stator coils from
the calculated coil resistance value.
[0026] The stator coils generate heat when energized. The heat is transmitted to and
warmsthe insulating member covering the stator coils to the substantially same temperature as
the stator coils. The stator coils and the insulating member thus have substantially the same
20 temperature. The temperature acquirer 22 outputs the estimated temperature of the stator coils
to the damage level determiner 23 as the temperature of the insulating member.
[0027] The damage level determiner 23 determines, for each target period, the damage
level based on the temperature of the insulating member received fromthe temperature acquirer
22 and on the relationship between the temperature and the service life of the insulating member.
25 The damage level indicates an elapsed time within the service life corresponding to the
temperature of the insulating member. The service life is a time period for which the
insulating member is usable. The service life changes in accordance with the temperature of
10
the insulating member. More specifically, the temperature and the service life of the insulating
member have the relationship of the service life being shorter for the temperature being higher.
The relationship between a service life LT and a temperature T (in K) of the insulating member
is expressed by the Arrhenius equation in Formula 1 below. In Formula 1 below, A is the
5 frequency factor, Ea is the activation energy, and R is the gas constant.
[0028]
(1)
[0029] In Embodiment 1, the damage level determiner 23 determines the damage level
being the ratio of the target period to the service life LT corresponding to the temperature of the
10 insulating member. More specifically, the damage level determiner 23 uses, as the damage
level, a value τ/LT resulting from dividing a target period τ by the service life LT. The damage
level determiner 23 outputs, as the damage level, the value τ/LT resulting from dividing the
target period τ by the service life LT to the determiner 24.
[0030] The determiner 24 determines the degree of deterioration of the insulating
15 member based on the damage level determined in each target period τ after the first use of the
conductor. More specifically, in a determination period starting at the first use of the conductor
and including multiple target periods τ, the determiner 24 determinesthe degree of deterioration
of the insulating member based on the damage level determined in each target period τ. In
Embodiment 1, the determiner 24 determines the degree of deterioration of the insulating
20 member based on a cumulative damage level being a cumulative value of the damage levels in
the determination period. For example, the determiner 24 calculates the cumulative damage
level in the determination period and determines whether the cumulative damage level has
reached a threshold or not. When the cumulative damage level in the determination period
reaches the threshold, the insulating member can be determined as having reached the end of
25 the service life. According to Miner’s rule, when the cumulative damage level of a member
reaches 1, the member can be determined as having reached the end of the service life. The
determiner 24 thus sets the threshold to 1 and determines whether the cumulative damage level
11
in the determination period has reached the threshold or not. The determiner 24 stores the
cumulative damage level into a storage that is not illustrated and transmits the determination
result to the destination 31.
[0031] The determination period starts at the first use of the conductor, such as when the
5 railway vehicle on which the electric motor 91 is mounted starts the first operation, and lasts
until maintenance of the insulating member in the electric motor 91 is performed, more
specifically, until the stator is impregnated with insulating varnish again. The cumulative
damage level stored in the storage is reset when the maintenance of the insulating member in
the electric motor 91 described above is performed.
10 [0032] The destination 31 that acquires the determination result from the deterioration
determining device 21 with the above structure includes, for example, a display installed in the
driver’s cab. Upon acquiring, from the deterioration determining device 21, the determination
result indicating that the insulating member has reached the end of the service life, the display
displays the acquired determination result on a screen.
15 [0033] FIG. 2 illustrates the hardware configuration of the deterioration determining
device 21 with the above structure. The deterioration determining device 21 includes a
processor 61, a memory 62, and an interface 63. The processor 61, the memory 62, and the
interface 63 are connected to one another with a bus 60. The function of each part of the
deterioration determining device 21 is implemented by software, firmware, or a combination of
20 software and firmware. The software and the firmware are described as programs and are
stored in the memory 62. The processor 61 reads and executes the programs stored in the
memory 62 to implement the function of each part described above. In other words, the
memory 62 stores programs for executing the processing of each part of the deterioration
determining device 21.
25 [0034] The memory 62 is, for example, a nonvolatile or volatile semiconductor memory
such as a random-access memory (RAM), a read-only memory (ROM), a flash memory, an
erasable programmable ROM (EPROM), or an electrically erasable programmable ROM
12
(EEPROM), a magnetic disk, a flexible disk, an optical disc, a compact disc, a minidisc, a digital
versatile disc (DVD), or another memory.
[0035] The deterioration determining device 21 is connected to, for example, the voltage
detection circuit 14, the current detection circuit 15, and the destination 31 through the interface
5 63. The interface 63 includes an interface module compliant with one or more standards as
appropriate for a connection destination.
[0036] The power converter 11 described above operates as described below.
When the operation command S1 includes the powering command, the power converter
11 in FIG. 1 converts DC power supplied from the power source to three-phase AC power and
10 supplies the three-phase AC power to the electric motor 91. The electric motor 91 is drivable
with the three-phase AC power and generates the propulsion for the railway vehicle.
[0037] More specifically, when the operation command S1 includes the powering
command, the power conversion circuit controller 13 determines a torque command value τ*
that is a target value of torque of the electric motor 91 in accordance with a target value of
15 acceleration of the railway vehicle indicated by the powering command and the measurement
value of the rotational speed of the electric motor 91 received from a speed sensor that is not
illustrated. The power conversion circuit controller 13 determines an excitation current
command value Id* and a torque current command value iq* in accordance with the torque
command value τ*. The power conversion circuit controller 13 determines an excitation
20 current value id and a torque current value iq by converting the measurement values of the phase
currents received from the current detection circuit 15 from three-phase coordinates to dq
rotation coordinates based on an estimated position θ estimated from the measurement value of
the rotational speed of the electric motor 91.
[0038] The power conversion circuit controller 13 determines an excitation voltage
25 command value Vd* based on the difference between the excitation current value id and the
excitation current command value id*, and determines a torque voltage command value Vq*
based on the difference between the torque current value iq and the torque current command
13
value iq*. The power conversion circuit controller 13 converts the excitation voltage
command value Vd* and the torque voltage command value Vq* from dq rotation coordinates
to three-phase coordinates based on the estimated position θ, and determines a U-phase voltage
command value Vu*, a V-phase voltage command value Vv*, and a W-phase voltage
5 command value Vw*. The power conversion circuit controller 13 generates and outputs
power conversion control signals S2 that control the switching operations of the switching
elements included in the power conversion circuit 12 based on each of the U-phase voltage
command value Vu*, the V-phase voltage command value Vv*, and the W-phase voltage
command value Vw* and a carrier wave.
10 [0039] When each ofthe power conversion control signals S2 is supplied to a gate signal
of each switching element in the power conversion circuit 12, each switching element starts the
switching operation. The power conversion circuit 12 then converts DC power to three-phase
AC power and supplies the three-phase AC power to the electric motor 91.
[0040] When the operation command S1 includes the braking command, the electric
15 motor 91 that operates as a generator supplies three-phase AC power to the power converter 11.
The power converter 11 converts the three-phase AC power supplied from the electric motor
91 to DC power and supplies the DC power to, through current collectors and power lines, other
railway vehicles traveling near the railway vehicle on which the power converter 11 is mounted.
When the three-phase AC power generated in the electric motor 91 is supplied to and consumed
20 in the other railway vehicles, a regenerative braking force for decelerating the railway vehicle is
generated.
[0041] More specifically, when the operation command S1 includes the braking
command, the power conversion circuit controller 13 acquires the measurement value of the
voltage across the terminals of the capacitor C1 from a voltage sensor that is not illustrated and
25 acquires measurement values of the phase currents flowing from the electric motor 91 to the
power conversion circuit 12 from the current detection circuit 15. The power conversion
circuit controller 13 determines a voltage command value indicating a target value of a voltage
14
output from the power conversion circuit 12 in accordance with the measurement value of the
voltage across the terminals of the capacitor C1 and the measurement values of the phase
currents flowing from the electric motor 91 to the power conversion circuit 12.
[0042] The target value of the voltage output from the power conversion circuit 12 is, for
5 example, a value within a target voltage range that is higher than the pantograph voltage and
indicates a voltage range in which regenerative braking is usable. The power conversion
circuit controller 13 generates and outputs the power conversion control signals S2 that control
the switching operations of the switching elements included in the power conversion circuit 12
based on the voltage command value.
10 [0043] When each of the power conversion control signals S2 is supplied to the gate
signal of each switching element in the power conversion circuit 12, each switching element
starts the switching operation. The power conversion circuit 12 thus converts three-phase AC
power supplied from the electric motor 91 to DC power and charges the capacitor C1 with the
DC power.
15 [0044] When the railway vehicle on which the power converter 11 is mounted is near
another railway vehicle accelerating, the power generated in the electric motor 91 is supplied to
and consumed in the other railway vehicle as described above. This generates the regenerative
braking force for decelerating the railway vehicle.
[0045] Independently of the processing by the power converter 11 described above, the
20 deterioration determining device 21 performs determination of the degree of deterioration of the
insulating member in the electric motor 91. When the railway vehicle on which the electric
motor 91 is mounted starts the first operation, the deterioration determining device 21 starts
determining the degree of deterioration illustrated in FIG. 3. For example, when a pantograph
raising button installed in the driver’s cab in the railway vehicle on which the electric motor 91
25 is mounted is operated to cause the railway vehicle to start the first operation, the deterioration
determining device 21 starts determining the degree of deterioration illustrated in FIG. 3. The
deterioration determining device 21 then continuously repeats the determination of the degree
15
of deterioration illustrated in FIG. 3 in each target period τ = TP1 during the operation of the
railway vehicle.
[0046] The temperature acquirer 22 calculates the coil resistance value of the electric
motor 91 based on the measurement values of the phase voltages received from the voltage
5 detection circuit 14 and the measurement values of the phase currents received from the current
detection circuit 15 (step S11). For example, with a weak current flowing through the stator
coils alone, the temperature acquirer 22 calculates a line voltage between U- and V-phases based
on the measurement values of U-phase voltage and of V-phase voltage received from the
voltage detection circuit 14. The temperature acquirer 22 calculates a coil resistance value Re
10 of the U-phase stator coil using Formula 2 below based on a line voltage Vuv between U- and
V-phases and a measurement value Iu of a U-phase current received from the current detection
circuit 15. The temperature acquirer 22 stores the calculated coil resistance value into a storage
that is not illustrated in FIG. 1.
[0047]
15 (2)
[0048] To calculate the coil resistance value using the above Formula 2, a current supplier
preferably supplies a weak current to the stator coils alone. When the coil resistance value is
calculated with a weak current from the current supplier flowing through the stator coils alone,
the coil resistance value can also be calculated during coasting in which the electric motor 91
20 receives no power from the power converter 11.
[0049] As illustrated in FIG. 3, the temperature acquirer 22 estimates the temperature of
the insulating member in the electric motor 91 from the coil resistance value calculated in step
S11 (step S12). Step S12 is described in detail below.
[0050] The temperature acquirer 22 estimates the temperature of the stator coils that are
25 conductors from the coil resistance value calculated in step S11 and the coil resistance value
calculated in the last target period τ. The temperature acquirer 22 stores the estimated
temperature of the stator coils into the storage that is not illustrated in FIG. 1. In Embodiment
16
1, the temperatures of the U-, V-, and W-phase stator coils included in the same electric motor
91 change in a substantially similar manner, and the temperature of the U-phase stator coil
estimated based on the coil resistance value of the U-phase stator coil calculated in step S11 is
used as the temperature of the stator coils in the electric motor 91.
5 [0051] For example, a temperature T’I of the stator coils in an i-th target period τi is
calculated using Formula 3 below. In Formula 3 below, Rei is a coil resistance value in the ith target period τi, Rei−1 is a coil resistance value in a (i−1)th target period τi−1, β is an inverse of
the temperature coefficient of resistance, and T’i−1 is a temperature of the stator coils in the
(i−1)th target period τi−1, where I is any natural number. In the first target period τ1 in which I
10 = 1, a temperature T0 of the stator coils is ordinary temperature such as 20 °C, and Re0 is a coil
resistance value at ordinary temperature. The temperature acquirer 22 prestores information
about the temperature T’0 of the stator coils and the coil resistance value R0. The inverse β of
the temperature coefficient of resistance is determined by a material for the conductor. For the
stator coils formed from copper, for example, the value of β is 235.
15 [0052]
(3)
[0053] Heat is transmitted from the stator coils to the insulating member and warm the
insulating member to substantially the same temperature as the stator coils. The insulating
member covering the stator coils thus have substantially the same temperature as the stator coils.
20 The temperature acquirer 22 outputs, as the temperature Ti of the insulating member, the
temperature T’I of the stator coils estimated as described above to the damage level determiner
23.
[0054] As illustrated in FIG. 3, the damage level determiner 23 determines the damage
level being the ratio of the target period τ to the service life LT corresponding to the temperature
25 of the insulating member in accordance with the temperature of the insulating member
estimated by the temperature acquirer 22 in step S12 (step S13). Step S13 is described in detail
below.
17
[0055] The damage level determiner 23 determines the service life LT of the insulating
member in accordance with the temperature of the insulating member estimated by the
temperature acquirer 22. As described above, the temperature T and the service life LT of the
insulating member have the relationship of the service life LT being shorter for the temperature
5 being higher, as expressed by the Arrhenius equation in Formula 1 above. As illustrated in
FIG. 4, for example, an inverse 1/T of the temperature of the insulating member correlates
positively with a logarithm logLT of the service life LT of the insulating member. The
horizontal axis in FIG. 4 indicates the inverse 1/T of the temperature of the insulating member
(in 1/K). The vertical axis in FIG. 4 indicates the logarithm logLT of the service life LT. In
10 the example in FIG. 4, the inverse 1/T of the temperature of the insulating member and the
logarithm logLT of the service life LT have a linear relationship. For example, the damage
level determiner 23 determines a service life LTi of the insulating member corresponding to the
temperature Ti of the insulating member in the i-th target period τi based on the graph illustrated
in FIG. 4.
15 [0056] After determining the service life LT corresponding to the temperature of the
insulating member as described above, the damage level determiner 23 determines the damage
level being the ratio of the target period τ to the service life LT corresponding to the temperature
of the insulating member. More specifically, the damage level determiner 23 calculates a
damage level Di in the i-th target period τi using Formula 4 below. In Formula 4 below, τi
20 indicates the length of the i-th target period τi. In Embodiment 1, τi is a fixed value TP1. The
damage level Di in the i-th target period τi indicates the ratio of, to the service life LT of the
insulating member corresponding to the temperature of the insulating member in the i-th target
period τi, a time elapsed within the service life LT when the i-th target period τi passes. The
damage level determiner 23 outputs the damage level Di calculated as described above to the
25 determiner 24.
[0057]
(4)
18
[0058] The determiner 24 determineswhether any deterioration of the insulating member
occurs, based on the damage level Di calculated in step S13 in each target period τ. More
specifically, as illustrated in FIG. 3, the determiner 24 calculates the cumulative damage level
(step S14). A cumulative damage level ACCi from the first target period τ1 to the i-th target
5 period τi is expressed using Formula 5 below. In Embodiment 1, τ1 = τ2 = τ3 = ... = τi = TP1 in
Formula 5 below.
[0059]
(5)
[0060] The determiner 24 determines whether the cumulative damage level ACCi has
10 reached a threshold or not (step S15). When the cumulative damage level ACCi has reached
the threshold (Yes in step S15), the insulating member can be determined as having reached the
end of the service life. The determiner 24 thus outputs, to the destination 31, the determination
result indicating that the insulating member has reached the end of the service life (step S16).
When the processing in step S16 is complete, the deterioration determining device 21 repeats
15 the processing described above from step S11.
[0061] When the cumulative damage level ACCi has not reached the threshold (No in
step S15), the insulating member can be determined as not having reached the end of the service
life. The deterioration determining device 21 thus does not perform the processing in step S16
and repeats the processing described above from step S11.
20 [0062] The cumulative damage level ACCi having reached 1, or in other words, the sum
of the ratios of the target period τ to the service life LT of the insulating member having reached
1 indicates that the service life LT of the insulating member has passed. Thus, with the
threshold being 1, the insulating member can be determined as having reached the end of the
service life when the cumulative damage level ACCi reaches the threshold.
25 [0063] For example, when the temperature is a constant temperature Te1 from the first
target period τ1 to the i-th target period τi, the service life LT corresponding to the temperature
Te1 is Lte1 as illustrated in FIG. 4, and thus, LT1 = LT2 = LT3 = ... = LTi = Lte1. The
19
cumulative damage level ACCi is thus expressed as i∙TP1/Lte1. In other words, the cumulative
damage level ACCi is the ratio of the length from the first target period τ1 to the i-th target period
τi to the service life Lte1. When the cumulative damage level ACCi expressed as i∙TP1/Lte1
reaches the threshold, the insulating member can be determined as having reached the end of
5 the service life.
[0064] When the temperature changes between the first target period τ1 and the i-th target
period τi, the cumulative damage level ACCi is described as below. In one example with I =
100, the temperature of the insulating member is Te1 from the first target period τ1 to the 50th
target period τ50, and is Te2 in the 51st target period τ51 and subsequent target periods τ. In this
10 case, as illustrated in FIG. 4, the service life LT corresponding to the temperature Te1 is Lte1,
and the service life LT corresponding to the temperature Te2 is Lte2. Thus, LT1 = LT2 = LT3
= ... = LT50 = Lte1, and LT51 = LT52 = ... = LT100 = Lte2. A cumulative damage level ACC100
is thus expressed as 50∙TP1/Lte1 + 50∙TP1/Lte2. When the temperature of the insulating
member changes as described above as well, the degree of deterioration of the insulating
15 member can be accurately determined using the damage level Di indicating an elapsed time
within the service life LT of the insulating member corresponding to the temperature.
[0065] With the threshold less than 1, such as 0.8, the insulating member can be
determined as approaching the end of the service life when the cumulative damage level ACCi
reaches the threshold. In this case, the determiner 24 outputs, to the destination 31, the
20 determination result indicating that the insulating member is approaching the end of the service
life.
[0066] When the destination 31 acquires the determination result indicating that the
insulating member has reached or is approaching the end of the service life from the
deterioration determining device 21 and displays the determination result on the screen,
25 maintenance is preferably performed, more specifically, the stator of the electric motor 91 is
preferably impregnated with insulating varnish again.
[0067] As described above, the deterioration determining device 21 according to
20
Embodiment 1 determines the degree of deterioration of the insulating member based on the
damage level indicating an elapsed time within the service life LT corresponding to the
temperature of the insulating member, more specifically, the damage level being the ratio of the
target period τ to the service life LT corresponding to the temperature of the insulating member
5 determined in each target period τ. This allows more accurate determination of the degree of
deterioration of the insulating member covering the conductor than a deterioration determining
device that converts the operation time at an actual temperature to the operation time at a
reference temperature and determines, by comparing the integrated value of the converted
operation time and the service life span at the reference temperature, whether any deterioration
10 of the insulating member occurs.
[0068] Embodiment 2
Deterioration determination performed by the deterioration determining device 21 is not
limited to the above example. A deterioration determining device 21 that determines the
degree of deterioration of an insulating member with processing different from the processing
15 in Embodiment 1 is described in Embodiment 2 by focusing on the differences from
Embodiment 1.
[0069] The deterioration determining device 21 illustrated in FIG. 5 includes the same
components as the deterioration determining device 21 according to Embodiment 1. Unlike
the deterioration determining device 21 according to Embodiment 1, the deterioration
20 determining device 21 according to Embodiment 2 receives the operation command S1 from
the driver’s cab, receives the U-phase voltage command value Vu*, the V-phase voltage
command value Vv*, and the W-phase voltage command value Vw* from the power
conversion circuit controller 13, and receives the measurement values of the phase currents from
the current detection circuit 15.
25 [0070] The temperature acquirer 22 calculates the resistance value of the stator coils that
are conductors based on the U-phase voltage command value Vu*, the V-phase voltage
command value Vv*, and the W-phase voltage command value Vw* received from the power
21
conversion circuit controller 13 as well as the measurement values of the phase currents received
from the current detection circuit 15. The temperature acquirer 22 estimates the temperature
of the stator coils from the calculated coil resistance value. As in Embodiment 1, the stator
coils and the insulating member covering the stator coils may have substantially the same
5 temperature, the temperature acquirer 22 outputs the estimated temperature of the stator coils as
the temperature of the insulating member.
[0071] The stator coils at different positions may have different surface areas that are
exposed to the air and may thus have different temperatures. More specifically, the stator coils
at some positions may have temperatures higher than the temperature of the stator coils
10 estimated from the coil resistance value. The insulating member covering the stator coils may
have portions with temperatures higher than the temperature of the insulating member output
from the temperature acquirer 22. The damage level determiner 23 included in the
deterioration determining device 21 according to Embodiment 2 thus performs correction to
increase the temperature of the insulating member received from the temperature acquirer 22.
15 [0072] For example, the damage level determiner 23 multiplies the temperature of the
insulating member received from the temperature acquirer 22 by a factor h1 greater than 1. The
factor h1 is, for example, a value that corresponds to the maximum temperature of the stator
coils when the average temperature of the stator coils is 1 based on distribution data of
temperatures of the stator coils.
20 [0073] The damage level determiner 23 determines, in each target period τ, the damage
level indicating an elapsed time within the service life LT corresponding to the temperature of
the insulating member based on the temperature of the insulating member corrected as described
above and on the relationship between the temperature and the service life LT of the insulating
member. The damage level indicating an elapsed time within the service life LT when the
25 target period τ passes can thus be determined as appropriate for a hot spot at which the stator
coils have higher temperatures.
[0074] The damage level determiner 23 determines the damage level based on the
22
corrected temperature of the insulating member and on the relationship between the temperature
and the service life LT of the insulating member in each target period τ with a length changeable
in accordance with the operation command S1. For example, the damage level determiner 23
causes a target period τ = TP2 during accelerating or decelerating, or in other words, when the
5 operation command S1 includes the powering command or the braking command, to be shorter
than a target period τ = TP3 during coasting, or in other words, when the operation command
S1 includes the coasting command. The damage level determiner 23 can thus determine the
service life LT corresponding to the temperature of the insulating member more frequently and
can determine the damage level indicating an elapsed time within the service life LT more
10 frequently during acceleration or deceleration in which the temperature of the stator coils in the
electric motor 91 may change rapidly. Thus, the damage level indicating an elapsed time
within the service life LT when the target period τ passes can be determined accurately.
[0075] The deterioration determining device 21 has the same hardware configuration as
the deterioration determining device 21 according to Embodiment 1. However, unlike in
15 Embodiment 1, the deterioration determining device 21 is connected to, for example, the current
detection circuit 15, the power conversion circuit controller 13, the destination 31, and an invehicle device including a master controller installed in the driver’s cab through the interface 63.
[0076] The deterioration determining device 21 with the above structure determines the
degree of deterioration in the manner described below. When the railway vehicle on which the
20 electric motor 91 is mounted starts the first operation, the deterioration determining device 21
starts determining the degree of deterioration illustrated in FIG. 6. The processing in steps S11
and S12 is the same as the processing performed by the deterioration determining device 21
illustrated in FIG. 3.
[0077] The damage level determiner 23 performs correction to increase the temperature
25 of the insulating member estimated in step S12 (step S21). The damage level determiner 23
determines the damage level being the ratio of the target period τ to the service life LT
corresponding to the temperature of the insulating member in accordance with the temperature
23
of the insulating member corrected in step S21 (step S13). The processing in subsequent steps
S14 to S16 is the same as the processing performed by the deterioration determining device 21
illustrated in FIG. 3.
[0078] As described above, the deterioration determining device 21 according to
5 Embodiment 2 performs correction to increase the temperature of the insulating member and
then determines the service life LT based on the corrected temperature of the insulating member.
Thus, when the temperature varies in the insulating member, the degree of deterioration of the
insulating member can be determined using a portion of the insulating member that has a higher
temperature than other portions and thus has a shorter service life LT as a reference.
10 Additionally, the deterioration determining device 21 determines the service life LT
corresponding to the temperature of the insulating member more frequently during acceleration
or deceleration in which the temperature of the insulating member may change rapidly than in
coasting. This increases the accuracy in determining the degree of deterioration of the
insulating member.
15 [0079] The present disclosure is not limited to the above embodiments. The hardware
configuration and the flowcharts described above are examples, and may be changed or
modified as appropriate.
[0080] The target of determination performed by the deterioration determining device 21
is not limited to the stator coils in the electric motor 91 and is any insulating member that covers
20 the conductor. In an example, a deterioration determining device 21 illustrated in FIG. 7
determines the degree of deterioration of an insulating member covering a conductor included
in the reactor L1. The deterioration determining device 21 has the same structure as in
Embodiments 1 and 2.
[0081] The power converter 11 includes a voltage detection circuit 16 that measures a
25 voltage across the terminals of the reactor L1 and a current detection circuit 17 that measures a
current flowing through the reactor L1.
[0082] The voltage detection circuit 16 is connected in parallel to the reactor L1 and
24
measures the value of the voltage across the terminals of the reactor L1. The voltage detection
circuit 16 transmits the measurement value of the voltage across the terminals to the
deterioration determining device 21.
[0083] The current detection circuit 17 includes a current sensor being a Hall device
5 attached to a busbar that electrically connects the reactor L1 and the power conversion circuit
12, and measures the value of the current flowing through the reactor L1. The current detection
circuit 15 transmits the measurement value of the current to the deterioration determining device
21.
[0084] The reactor L1 includes a conductive wire and an insulating member covering the
10 conductive wire. The conductive wire covered with the insulating member is wound to form
a disk coil.
[0085] The temperature acquirer 22 calculates the coil resistance value of the disk coil
included in the reactor L1 based on the measurement value of the voltage across the terminals
of the reactor L1 received from the voltage detection circuit 16 and the measurement value of
15 the current flowing through the reactor L1 received from the current detection circuit 17. More
specifically, the temperature acquirer 22 divides the measurement value of the voltage across
the terminals of the reactor L1 by the measurement value of the current flowing through the
reactor L1 to calculate the coil resistance value. As in Embodiments 1 and 2, the temperature
acquirer 22 estimates the temperature of the conductive wire of the disk coil from the calculated
20 coil resistance value.
[0086] The conductive wire of the disk coil generates heat when energized, and the heat
is transmitted to and warm the insulating member covering the conductive wire to substantially
the same temperature as the conductive wire. The conductive wire of the disk coil thus has
substantially the same temperature as the insulating member. The temperature acquirer 22
25 outputs, as the temperature of the insulating member, the estimated temperature of the disk coil
to the damage level determiner 23.
[0087] With the damage level determiner 23 and the determiner 24 performing the same
25
processing as in Embodiments 1 and 2, the degree of deterioration of the insulating member in
the reactor L1 can be determined.
[0088] The temperature acquirer 22 may acquire the temperature of the insulating
member with a method other than the examples described above. In an example, the
5 temperature acquirer 22 may output a moving average value of temperatures of the insulating
member acquired at different timings as the temperature of the insulating member. For
example, the temperature acquirer 22 included in the deterioration determining device 21
according to Embodiment 1 estimates, in each target period τ, the temperature of the stator coils
that are conductors from the measurement values of the phase voltages received from the
10 voltage detection circuit 14 and the measurement values of the phase currents received from the
current detection circuit 15.
[0089] The temperature acquirer 22 calculates the moving average value of the estimated
temperatures of the stator coils and outputs the calculated moving average value to the damage
level determiner 23 as a temperature Ti of the insulating member. For example, in the i-th
15 target period τi, a moving average value T’i_avg of temperatures of the stator coils estimated in
the latest j target periods τ is expressed using Formula 6 below.
[0090]
(6)
[0091] To reduce a deviation between the moving average value of temperatures and the
20 actual temperature, the moving average value T’i_avg of temperatures of the stator coils expressed
using Formula 7 below is preferably used.
[0092]
(7)
[0093] In this case, the deterioration determining device 21 starts determining the degree
25 of deterioration illustrated in FIG. 8 when the railway vehicle on which the electric motor 91 is
mounted starts the first operation. The processing in step S11 is the same as the processing
performed by the deterioration determining device 21 illustrated in FIG. 3. The temperature
26
acquirer 22 estimates the temperature of the stator coils that are conductorsin the electric motor
91 from the coil resistance value calculated in step S11, calculates the moving average value of
temperatures of the stator coils, and outputs, as an estimated temperature of the insulating
member, the calculated moving average value to the damage level determiner 23 (step S22).
5 The processing in subsequent steps S13 to S16 is the same as the processing performed by the
deterioration determining device 21 according to Embodiment 1 illustrated in FIG. 3.
[0094] When the temperature of the conductor changes greatly, a change in the estimated
temperature of the insulating member can be reduced by using the moving average value of
temperatures of the conductor as the temperature of the insulating member. This suppresses
10 great change in the damage level indicating an elapsed time within the service life LT
corresponding to the temperature of the insulating member, increasing the accuracy in
determining the degree of deterioration of the insulating member.
[0095] In another example, the temperature acquirer 22 may acquire, from the power
conversion circuit controller 13, the U-phase voltage command value Vu*, the V-phase voltage
15 command value Vv*, and the W-phase voltage command value Vw*, as well as a U-phase
current command value, a V-phase current command value, and a W-phase current command
value that are acquired by converting the excitation current command value id* and the torque
current command value iq* from dq rotation coordinates to three-phase coordinates based on
the estimated position θ. The temperature acquirer 22 may then calculate the coil resistance
20 value based on the acquired command values. With the coil resistance value calculated based
on the command values, the detection circuits are eliminated, reducing the computational load
for computing the resistance value based on detected values.
[0096] In another example, the temperature acquirer 22 may acquire a measurement
value from at least one temperature sensor that measures the temperature of the conductor to
25 determine the temperature of the insulating member based on the measurement value of the at
least one temperature sensor. More specifically, the temperature acquirer 22 may use, as the
temperature of the insulating member, an average value of measurement values from multiple
27
temperature sensors arranged in a longitudinal direction of the stator coils, or in other words, a
direction in which the rotation axis of the electric motor 91 extends. The temperature sensors
may be, for example, thermocouples embedded between the stator coils.
[0097] In another example, the temperature acquirer 22 may calculate the coil resistance
5 value of each of the U-, V-, and W-phase stator coils included in the electric motor 91 and
estimate the temperature of an insulating member covering the U-phase stator coil, an insulating
member covering the V-phase stator coil, or an insulating member covering the W-phase stator
coil from each coil resistance value. In this case, the damage level determiner 23 may
determine the damage level of each insulating member covering the U-phase stator coil, the
10 insulating member covering the V-phase stator coil, or the insulating member covering the Wphase stator coil. The determiner 24 may determine the degree of deterioration of each
insulating member covering the U-phase stator coil, the insulating member covering the Vphase stator coil, or the insulating member covering the W-phase stator coil.
[0098] To determine the temperature of the insulating member more accurately, the
15 temperature acquirer 22 may calculate the coil resistance value using an L-shaped equivalent
circuit of the induction motor to estimate the temperature of the stator coils from the calculated
coil resistance value. For example, a coil resistance value Reu of the U-phase stator coil is
expressed using Formula 8 below. In Formula 8 below, Vpu indicates the phase voltage of the
U phase, ω indicates the source angular frequency, L1u indicates a primary inductance, and L2
20 indicates a secondary inductance. The number of poles in the electric motor 91 is p, and TM
indicates the torque of the electric motor 91. The primary inductance L1u and the secondary
inductance L2 may be values in a shipping test.
[0099]
(8)
25 [0100] The source angular frequency ω is determined from the source angular frequency
ω based on the excitation current command value Id*, the torque current command value Iq*,
and the rotational speed of the electric motor 91. The temperature acquirer 22 acquires, from
28
the power conversion circuit controller 13 as illustrated in FIG. 9, the torque command value τ*
and the source angular frequency ω determined based on the excitation current command value
Id*, the torque current command value Iq*, and the rotation speed of the electric motor 91. The
temperature acquirer 22 uses the torque command value τ*as electric motor torque TM.
5 [0101] In Formula 8 above, Iu’ is a primary conversion current and is expressed using
Formula 9 below. In Formula 9 below, Iu is a phase current of the U phase. In Formula 9
below, Imu is a no-load current and is expressed using Formula 10 below. In Formula 10 below,
rmu is combined excitation resistance and is expressed using Formula 11 below. In Formula 10
below, xmu is combined excitation reactance and is expressed using Formula 12 below.
10 Impedance Z for the L-shaped equivalent circuit of the induction motor is expressed by Z = rmu
+ jxmu, using the imaginary unit j. In Formulas 11 and 12, Rm indicates iron loss resistance, and
Lm indicates excitation inductance. The iron loss resistance Rm and the excitation inductance
Lm may be values in the shipping test.
[0102]
15 (9)
[0103]
(10)
[0104]
(11)
20 [0105]
(12)
[0106] The temperature acquirer 22 calculates a coil resistance value Rev of the V-phase
stator coil and a coil resistance value Rew of the W-phase stator coil in the same manner as the
coil resistance value Reu. The temperature acquirer 22 calculates an average coil resistance
25 value Reavg based on the coil resistance values Reu, Rev, and Rew as in Formula 13 below.
[0107]
(13)
29
[0108] The temperature acquirer 22 uses, as the coil resistance value Re, the coil
resistance value Reu, Rev, or Rew that has the greatest value when the average coil resistance
value Reavg is subtracted. In other words, the temperature acquirer 22 uses, as the coil resistance
value Re, the coil resistance value Reu, Rev, or Rew that has the greatest values of Reu – Reavg,
5 Rev – Reavg, and Rew – Reavg. The temperature acquirer 22 estimates the temperature of the
stator coils from the coil resistance value Re determined as described above.
[0109] The temperature acquirer 22 may calculate the coil resistance value using a Tshaped equivalent circuit of the induction motor to estimate the temperature of the stator coils
from the calculated coil resistance value.
10 [0110] The temperature of the stator coils may be estimated with a method other than the
examples described above. In an example, the temperature acquirer 22 may use, in Formula 3
above, the primary resistance value Re0 measured in the shipping test in place of Rei−1, and
temperature T0 measured in the shipping test in place of T’i−1. More specifically, the
temperature acquirer 22 may calculate the temperature T’I of the stator coils using Formula 14
15 below.
[0111]
(14)
[0112] The length of the target period τ is not limited to the example described above,
and may change in accordance with a parameter other than the operation command S1. In an
20 example, the length of the target period τ may change in accordance with the operating state of
the device mounted on the railway vehicle. More specifically, for a railway vehicle on which
multiple electric motors 91 are mounted, the length of the service life LT may change in
accordance withwhether at least one of the electric motors 91 has an abnormality. For example,
the damage level determiner 23 may acquire information as to whether each electric motor 91
25 has an abnormality from an abnormality detector that detects an abnormality in the electric
motors 91, and may cause a target period τ = TP4, which is the target period when at least one
of the electric motors 91 has an abnormality, to be shorter than a target period τ = TP5, which is
30
the target period when none of the electric motors 91 has an abnormality. When any of the
electric motors 91 has an abnormality, other electric motors 91 without an abnormality are to
increase output to cause the railway vehicle to travel at a target speed. The temperatures of the
other electric motors 91 without an abnormality thus rise.
5 [0113] With the length of the service life LT changing in accordance withwhether at least
one of the electric motors 91 has an abnormality, the damage level determiner 23 can determine
the service life LT corresponding to the temperature of the insulating member more frequently
when the temperature of the stator coils in the electric motor 91 may increase, and can determine
the damage level indicating an elapsed time within the service life LT more frequently. An
10 elapsed time within the service life LT when the target period τ passes can thus be determined
accurately.
[0114] The insulating member being the target of determination performed by the
deterioration determining device 21 is not limited to varnish. In an example, the insulating
member may be insulating resin, such as polyimide or polyphenylene sulfide.
15 [0115] The deterioration determining device 21 may be implemented as a functional
component of a train information management system. The deterioration determining device
21 may not be mounted on a railway vehicle and may be installed, for example, in an operation
control office.
[0116] The electric motor 91 may be either a three-phase induction motor or a three-phase
20 synchronous motor. The electric motor 91 is not limited to a three-phase motor and may be,
for example, a single-phase motor or a DC motor. The electric motor 91 may be an inner rotor
or an outer rotor.
[0117] The deterioration determining device 21 may be implemented by a processing
circuit 71 as illustrated in FIG. 10. The processing circuit 71 is connected to, for example, the
25 voltage detection circuit 14, the current detection circuit 15, and the destination 31 through an
interface circuit 72. When the processing circuit 71 is dedicated hardware, the processing
circuit 71 is, for example, a single circuit, a complex circuit, a programmed processor, a parallel
31
programmed processor, an application-specific integrated circuit (ASIC), a field-programmable
gate array (FPGA), or a combination of two or more of these. Each part of the deterioration
determining device 21 may be implemented by an individual processing circuit 71 or by a
common processing circuit 71.
5 [0118] The deterioration determining device 21 may have some functions implemented
by dedicated hardware, and other functions implemented by software or firmware. For
example, the temperature acquirer 22 may be implemented by the processing circuit 71
illustrated in FIG. 10, and the damage level determiner 23 and the determiner 24 may be
implemented by the processor 61 illustrated in FIG. 2 reading and executing the programs stored
10 in the memory 62.
[0119] 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
15 be regarded in an illustrative rather than a restrictive 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
[0120]
20 11 Power converter
11a, 11b Input terminal
12 Power conversion circuit
13 Power conversion circuit controller
14, 16 Voltage detection circuit
25 15, 17 Current detection circuit
21 Deterioration determining device
22 Temperature acquirer
32
23 Damage level determiner
24 Determiner
31 Destination
60 Bus
5 61 Processor
62 Memory
63 Interface
71 Processing circuit
72 Interface circuit
10 91 Electric motor
C1 Capacitor
L1 Reactor
S1 Operation command
S2 Power conversion control signal

WE CLAIM:
[Claim 1] A deterioration determining device, comprising:
a temperature acquirer to acquire a temperature of an insulating member covering a
conductor;
5 a damage level determiner to determine, for each target period, a damage level based on
the temperature of the insulating member acquired by the temperature acquirer and on a
relationship between a temperature and a service life of the insulating member, the service life
being a time period for which the insulating member is usable, the damage level indicating an
elapsed time within the service life corresponding to the temperature of the insulating
10 member acquired by the temperature acquirer; and
a determiner to determine a degree of deterioration of the insulating member based on
the damage level determined for each target period.
[Claim 2] The deterioration determining device according to claim 1, wherein
15 the determiner determinesthe degree of deterioration of the insulating member based on
the damage level determined for each target period after a first use of the conductor.
[Claim 3] The deterioration determining device according to claim 1 or 2, wherein
the damage level determiner determines the damage level being a ratio of the target
20 period to the service life corresponding to the temperature of the insulating member acquired by
the temperature acquirer.
[Claim 4] The deterioration determining device according to any one of claims 1 to
3, wherein
25 the determiner determinesthe degree of deterioration of the insulating member based on
a cumulative damage level.
34
[Claim 5] The deterioration determining device according to any one of claims 1 to
4, wherein
the temperature and the service life of the insulating member have a relationship of the
service life being shorter for the temperature being higher.
5
[Claim 6] The deterioration determining device according to any one of claims 1 to
5, wherein
the temperature acquirer acquires a temperature of the conductor and uses the acquired
temperature of the conductor as the temperature of the insulating member.
10
[Claim 7] The deterioration determining device according to claim 6, wherein
the temperature acquirer estimates a resistance value of the conductor from a current
flowing through the conductor and from a potential of the conductor, estimates the temperature
of the conductor from the estimated resistance value, and uses the estimated temperature of the
15 conductor as the temperature of the insulating member.
[Claim 8] The deterioration determining device according to claim 6 or 7, wherein
the temperature acquirer calculates a moving average value of temperatures of the
insulating member acquired at different timings and uses the moving average value as the
20 temperature of the insulating member.
[Claim 9] The deterioration determining device according to any one of claims 1 to
8, wherein
the damage level determiner performs correction to increase the temperature of the
25 insulating member acquired by the temperature acquirer for each target period and determines
the damage level based on the temperature of the insulating member after the correction and on
the relationship between the temperature and the service life of the insulating member.
35
[Claim 10] The deterioration determining device according to any one of claims 1 to
9, wherein
the temperature acquirer acquires the temperature of the insulating member covering the
5 conductor included in a device mounted on a railway vehicle.
[Claim 11] The deterioration determining device according to claim 10, wherein
the damage level determiner determines the damage level for each target period with a
length changeable in accordance with an operation command for the railway vehicle.
10
[Claim 12] The deterioration determining device according to claim 10 or 11, wherein
the damage level determiner determines the damage level for each target period with a
length changeable in accordance with an operating state of the device.
15 [Claim 13] The deterioration determining device according to any one of claims 10 to
12, wherein
the temperature acquirer acquires the temperature of the insulating member covering the
conductor included in each of a plurality of electric motors mounted on the railway vehicle to
generate propulsion for the railway vehicle, and
20 the damage level determiner determines the damage level for each target period with a
length changeable based on whether an electric motor of the plurality of electric motors has an
abnormality.
[Claim 14] A deterioration determining method, comprising:
25 acquiring a temperature of an insulating member covering a conductor;
determining, for each target period, a damage level based on the acquired temperature of
the insulating member and on a relationship between a temperature of the insulating member
36
and a service life being a time period for which the insulating member is usable, the damage
level indicating an elapsed time within the service life corresponding to the acquired
temperature of the insulating member; and
determining a degree of deterioration of the insulating member based on the damage
5 level determined for each target period.