Deterioration diagnostic device, deterioration diagnostic system, and deterioration diagnostic method

Abstract

The present invention provides a deterioration diagnosis device, a deterioration diagnosis system, and a deterioration diagnosis method for determining whether or not the insulating material of an electric motor has deteriorated while the electric motor is installed in a vehicle. [Solution] The deterioration diagnostic device 1 comprises an antenna 11, a signal processing unit 12, a score determination unit 13, and a deterioration discrimination unit 14. The antenna 11 receives electromagnetic waves in the microwave frequency band radiated due to partial discharge occurring in the insulating material of the electric motor 41 and generates a received signal. The signal processing unit 12 samples the received signal at each sampling period and generates sampling data indicating the signal strength. The score determination unit 13 obtains a score indicating the strength of the signal intensity over the detection period from the sampling data of the detection period which includes multiple sampling periods. The deterioration discrimination unit 14 determines whether or not there is deterioration of the insulating material or whether or not there are signs of deterioration, based on the remaining life or operating time obtained from the relationship between the electric motor's service life and the score.

Description

Technical Field

[0001] The present disclosure relates to a degradation diagnosis device, a degradation diagnosis system, and a degradation diagnosis method.

Background Art

[0002] An electric motor mounted on a railway vehicle includes, for example, a rotor having a rotor core and rotor conductors inserted into slots formed on the outer peripheral surface of the rotor core, and a stator having a stator core and stator coils inserted into slots formed on the inner peripheral surface of the stator core. The electric motor further includes various insulating members such as an insulating member for insulating the stator core and the stator coils, and an insulating member for insulating the stator coils from each other. When the insulating member deteriorates, there is a possibility of a short circuit inside the electric motor, a ground fault to the outside of the electric motor, etc., so it is preferable to periodically check the degree of deterioration of the insulating member.

[0003] An example of a method for checking the degree of deterioration of an insulating member is disclosed in Patent Document 1. The partial discharge measurement method disclosed in Patent Document 1 measures the circumferential electromagnetic wave signal spatial intensity distribution by moving a plurality of electromagnetic wave sensors with fixed relative positions adjacent to the end of the stator coil. This partial discharge measurement method detects the defect position from the peak position of the partial discharge signal obtained from the measured electromagnetic wave signal spatial intensity distribution.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When determining the degree of deterioration of insulating materials using the partial discharge measurement method disclosed in Patent Document 1, it is necessary for a worker to remove the electric motor from the vehicle, disassemble it, and then move multiple electromagnetic wave sensors adjacent to the end of the stator coil to take measurements. Electric motors mounted on railway vehicles are large and attached to bogies under the vehicle floor, making maintenance work, including removal of the electric motor from the bogie and disassembly of the electric motor, complicated. For this reason, it is difficult to frequently monitor whether or not the insulating materials of the electric motor are deteriorating.

[0006] This disclosure is made in view of the circumstances described above, and aims to provide a deterioration diagnosis device, a deterioration diagnosis system, and a deterioration diagnosis method for determining whether or not the insulating material of an electric motor has deteriorated while the electric motor is mounted on a vehicle. [Means for solving the problem]

[0007] To achieve the above objective, the degradation diagnostic device of this disclosure comprises an antenna, a signal processing unit, a score determination unit, and a degradation discrimination unit. The antenna receives electromagnetic waves in the microwave frequency band radiated due to partial discharge occurring in the insulating material of the electric motor and generates a received signal. The signal processing unit samples the received signal at each sampling period and generates sampling data indicating the signal strength of the received signal. The score determination unit obtains a score indicating the strength of the signal strength over the detection period from the sampling data generated by the signal processing unit during a detection period that includes multiple sampling periods. The degradation discrimination unit obtains the remaining life, which is the time remaining until dielectric breakdown of the electric motor occurs, or the remaining operating time, which is the time remaining until the score of the electric motor reaches a score reference value determined according to the value that the signal strength can take when the insulating material is degraded, based on the relationship between the service life of the electric motor and the score, and determines whether or not there is degradation of the insulating material or whether or not there are signs of degradation of the insulating material. [Effects of the Invention]

[0008] The deterioration diagnostic device described herein generates sampling data indicating the signal strength of the received signal by sampling a received signal based on electromagnetic waves radiated due to partial discharge occurring in the insulating material of the electric motor. Based on a score indicating the strength of the signal over the detection period and the remaining life or operating time determined from the electric motor's service life, the device determines whether or not the insulating material is deteriorated or whether there are signs of deterioration. Therefore, it is possible to determine whether or not the insulating material of the electric motor is deteriorated or whether there are signs of deterioration while the electric motor is installed in a vehicle. [Brief explanation of the drawing]

[0009] [Figure 1] Block diagram showing the configuration of the deterioration diagnosis system according to Embodiment 1 [Figure 2] This figure shows the configuration of the electric motor that is the target of diagnosis by the deterioration diagnosis device according to Embodiment 1. [Figure 3] Diagram showing the strands for forming the stator coil of the electric motor in Embodiment 1. [Figure 4] This diagram shows how to bend the strands of wire to form the stator coil of the electric motor in Embodiment 1. [Figure 5] This figure shows a method for manufacturing the stator coil of an electric motor in Embodiment 1. [Figure 6] This figure shows a method for manufacturing the stator coil of an electric motor in Embodiment 1. [Figure 7] This diagram shows how the stator coils are attached to the stator core of the electric motor in Embodiment 1. [Figure 8] Cross-sectional view of the electric motor in Embodiment 1, taken along the line VIII-VIII in Figure 2. [Figure 9] Cross-sectional view of the insulating member of the electric motor in Embodiment 1 [Figure 10] Cross-sectional view showing an example of deterioration of the insulating material of the electric motor in Embodiment 1. [Figure 11] A diagram showing the hardware configuration of the degradation diagnosis device according to Embodiment 1. [Figure 12]Flowchart showing an example of the operation of the deterioration diagnosis process performed by the deterioration diagnosis apparatus according to Embodiment 1 [Figure 13] Figure showing an example of the distribution of signal intensities in Embodiment 1 [Figure 14] Figure showing an example of the number of occurrences of signal intensities in Embodiment 1 [Figure 15] Figure showing an example of the intensity reference value used by the deterioration diagnosis apparatus according to Embodiment 1 [Figure 16] Figure showing an example of the score reference value used by the deterioration diagnosis apparatus according to Embodiment 1 [Figure 17] Figure showing an example of the score of each motor obtained by the deterioration diagnosis apparatus according to Embodiment 1 [Figure 18] Figure showing an example of the relationship between the average value and the maximum value of the scores obtained by the deterioration diagnosis apparatus according to Embodiment 1 [Figure 19] Figure showing an example of the score appropriate range used by the deterioration diagnosis apparatus according to Embodiment 1 [Figure 20] Figure showing the configuration of the deterioration diagnosis apparatus according to Embodiment 2 [Figure 21] Figure showing the configuration of the motor that is the diagnosis target of the deterioration diagnosis apparatus according to Embodiment 2 [Figure 22] Arrow-view cross-sectional view taken along line XXII-XXII in FIG. 21 of the motor in Embodiment 2 [Figure 23] Figure showing a modified example of the hardware configuration of the deterioration diagnosis apparatus according to the embodiment

Mode for Carrying Out the Invention

[0010] Hereinafter, a deterioration diagnosis apparatus, a deterioration diagnosis system, and a deterioration diagnosis method according to embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or equivalent parts are denoted by the same reference numerals.

[0011] (Embodiment 1) Embodiment 1 describes a deterioration diagnostic device and a deterioration diagnostic system equipped with a deterioration diagnostic device for determining whether or not the insulating material of an electric motor mounted on a railway vehicle has deteriorated. The deterioration diagnostic system 100 shown in Figure 1 includes a deterioration diagnostic device 1 that determines whether or not the insulating material of an electric motor 41 driven by power supplied from a power converter 31 has deteriorated, and an output device 20 that acquires the determination result of the deterioration diagnostic device 1 and outputs the acquired determination result.

[0012] The degradation diagnosis device 1 comprises an antenna 11 that receives electromagnetic waves in the microwave frequency band, a signal processing unit 12 that samples the received signal generated by the antenna 11 and generates sampling data indicating the signal strength of the received signal, a score determination unit 13 that determines a score indicating the strength of the signal strength, and a degradation determination unit 14 that determines whether or not the insulating material of the electric motor 41 is degraded by comparing the score with a score reference value determined according to the values ​​that the signal strength can take when the insulating material is degraded. The degradation diagnosis device 1 operates by receiving power from a control power supply (not shown).

[0013] The power converter 31, which supplies power to the motor 41 that is the target of diagnosis by the deterioration diagnosis device 1 having the above configuration, is, for example, mounted on a railway vehicle using a DC power supply system and receives DC power from a current collector (not shown) that acquires DC power from a substation via a power supply line. The power converter 31 converts the DC power into three-phase AC power and supplies the three-phase AC power to the motor 41. The power converter 31 and the motor 41 are electrically connected by electric wires 32a, 32b, and 32c. The motor 41 is a three-phase motor and is driven by the three-phase AC power supplied from the power converter 31.

[0014] A high voltage is applied to the input terminal of the power converter 31 from the current collector. This high voltage is, for example, a DC voltage of 400V or more and 3000V or less. When the power converter 31 is controlled by a control device (not shown) using PWM (Pulse Width Modulation), the high-voltage pulse voltage output from the power converter 31 is applied to the stator coils 42 of the motor 41, specifically the U-phase coil 42a, V-phase coil 42b, and W-phase coil 42c. In the example in Figure 1, the U-phase coil 42a, V-phase coil 42b, and W-phase coil 42c are connected in a star configuration.

[0015] As described above, the electric motor 41, which receives power from the power converter 31, comprises, as shown in Figure 2, a frame 40 attached to the underside of the railway vehicle, a shaft 43 connected to the axle via couplings, gears, etc. (not shown), a pair of bearings 44 that rotatably support the shaft 43, a rotor 45 that rotates integrally with the shaft 43, a stator 49 attached to the frame 40 and radially opposite to the rotor 45, and a terminal box 51 attached to the frame 40 with electric wires 32a, 32b, and 32c arranged inside.

[0016] In Figure 2, the Z-axis represents the vertical direction, the Y-axis represents the width direction of the railway vehicle, and the X-axis represents the direction of travel of the railway vehicle. In other words, the railway vehicle moves in the positive X-axis direction or the negative X-axis direction. The X-axis, Y-axis, and Z-axis are orthogonal to each other.

[0017] The frame 40 has a cylindrical shape with both ends closed and houses a shaft 43, a pair of bearings 44, a rotor 45, and a stator 49. The outer surface of the frame 40 is attached to the underside of the railway vehicle by mounting members (not shown). Through holes 40a are formed on the upper surface of the frame 40 through which electric wires 32a, 32b, and 32c are passed. The through holes 40a are sealed by a terminal box 51 to prevent foreign matter such as dust and water droplets from entering the inside of the frame 40.

[0018] The shaft 43 is supported by a pair of bearings 44 so as to be rotatable around the rotation axis AX, which is shown by the dashed line in Figure 2. The rotation axis AX extends along the Y axis. One end of the shaft 43 in the positive Y-axis direction is connected to the axle via a coupling, gear mechanism, etc. The rotation of the shaft 43 is transmitted to the axle, generating the propulsion force of the railway vehicle.

[0019] A pair of bearings 44 are held in the frame 40 and rotatably support the shaft 43. In detail, each pair of bearings 44 is mounted on opposite ends of the frame 40 in the Y-axis direction.

[0020] The rotor 45 includes a rotor core 46 made of laminated steel plates that fits onto the shaft 43, a conductor bar 47 inserted into a slot formed on the outer circumferential surface of the rotor core 46, and a pair of short-circuit rings 48 attached to the conductor bar 47. The conductor bar 47 and the short-circuit rings 48 are made of a conductive material such as copper or aluminum. The rotor 45 having the above configuration rotates integrally with the shaft 43.

[0021] The stator 49 includes a stator core 50 made of laminated steel plates and attached to the inner circumferential surface of the frame 40, and stator coils 42 inserted into slots formed in the stator core 50.

[0022] The stator coil 42 is formed by processing the strands 61 shown in Figure 3 into a shape in which they are wound at least once in the direction indicated by the dashed arrow in Figure 4. The strands 61 shown in Figure 3 have a conductor 62 made of a conductive material such as copper or aluminum, and an insulating covering member 63 made of an insulating material such as vinyl or resin that covers the conductor 62. In Embodiment 1, as shown in Figure 4, the strands 61 are wound into a shape in which a part can be considered to be hexagonal.

[0023] As shown in Figure 5, the strands 61 are stacked in bundles in the area where they are wound. The stator coil 42 is formed by stacking multiple strands 61, for example, three strands 61, as shown in Figure 5, wrapping insulating tape 64 around the three stacked strands 61, and then wrapping insulating tape 64 on top of insulating tape 64 as shown in Figure 6. The insulating tape 64 is formed, for example, by bonding mica with resin and laminating it.

[0024] The stator coil 42 formed by the above-described processing is inserted into two slots 50a formed in the stator core 50, as shown in Figure 7. In Figure 7, the stator core 50 is represented in a straight line to avoid complicating the diagram. Two other slots 50a are provided between the two slots 50a into which one stator coil 42 is inserted. In Figure 7, the direction of the current is shown in the cross-section of the stator coil 42. The stator coils 42 arranged as shown in Figure 7 correspond to the U phase, V phase, and W phase in that order.

[0025] As shown in Figure 8, a cross-sectional view taken along the line VIII-VIII in Figure 2, two stator coils 42 are inserted into one slot 50a. The stator coils 42 inserted into the same slot 50a are separated and electrically insulated by an inter-coil insulating member 52 made of an insulating material such as vinyl, resin, or mica. The two stator coils 42 inserted into the slot 50a are fixed by a wedge 53. This prevents the stator coils 42 from coming out of the slot 50a.

[0026] By performing a varnish impregnation treatment on the stator coil 42 before insertion into the slot 50a, or on the stator 49 with the stator coil 42 inserted into the slot 50a, each component of the stator coil 42 is covered with an insulating material. Specifically, as shown in Figure 9, which is a partial enlargement of the area enclosed by the dotted line in Figure 8, insulating varnish 65 is filled between the insulating tapes 64. As a result, the stator core 50 and the strands 61 constituting the stator coil 42 are electrically insulated by the insulating tapes 64 and insulating varnish 65. By overlapping and winding the insulating tapes 64 around the multiple strands 61 as described above, the creepage distance can be increased, as shown by the dashed arrows in Figure 9.

[0027] If the varnish impregnation is insufficient, voids 65a may form inside the insulating varnish 65. If the voids 65a are small enough to ensure insulation between the wire strands 61 and the stator core 50, the electrically insulated state between the wire strands 61 and the stator core 50 will be maintained.

[0028] When a high-voltage pulse voltage output from the power converter 31 is applied to the stator coil 42, the high voltage is applied to the insulating layer, including the insulating tape 64 and insulating varnish 65. When a high voltage is applied to the insulating layer, partial discharge occurs, which can cause electrical degradation in the insulating layer, such as treeing degradation. Furthermore, when the motor 41 is energized, the stator coil 42 generates heat, causing thermal stress that applies external forces such as tensile force, compressive force, and bending stress to the insulating layer, which can cause mechanical degradation such as peeling and cracking of the insulating layer. In addition, environmental degradation such as changes in humidity, contact with contaminants, and immersion can occur. The above-mentioned electrical degradation, mechanical degradation, environmental degradation, or a combination thereof can lead to deterioration of the insulating material, specifically, expansion of voids 65a in the insulating layer, generation of cracks 65b, and expansion of cracks 65b.

[0029] If, for example, moisture penetrates the enlarged crack 65b, the insulation resistance between the wire 61 and the stator core 50 will decrease, potentially causing a short circuit between the wire 61 and the stator core 50 and resulting in dielectric breakdown.

[0030] As shown in Figure 10, when an enlarged void 65a and crack 65b occur, the amplitude of the microwave frequency electromagnetic waves generated by the partial discharge increases compared to the state where the void 65a is small and no crack 65b occurs, as shown in Figure 9.

[0031] When the insulating material deteriorates as described above, it becomes necessary to replace the motor 41 itself. In other words, the lifespan of the motor 41 is determined by the deterioration of the insulating material. Therefore, the deterioration diagnostic device 1 according to Embodiment 1 shown in Figure 1 determines whether or not the insulating material of the motor 41 has deteriorated based on electromagnetic waves in the microwave frequency band generated by partial discharge. The insulating material of the motor 41 includes the inter-coil insulating material 52, insulating tape 64, and insulating varnish 65. When the insulating material of the motor 41 deteriorates, electromagnetic waves in the microwave frequency band are radiated not only from the deteriorated area, but also from the ends of the U-phase coil 42a, V-phase coil 42b, and W-phase coil 42c, and from the wires 32a, 32b, and 32c connected to the U-phase coil 42a, V-phase coil 42b, and W-phase coil 42c, respectively.

[0032] Because partial discharge causes electromagnetic waves in the microwave frequency band, specifically electromagnetic waves between 300 MHz and 300 GHz, an antenna that receives electromagnetic waves in the microwave frequency band, such as a microstrip antenna, is used as the antenna 11. The antenna 11 comprises a dielectric substrate, a radiating element provided on one side of the dielectric substrate, and a ground conductor plate provided on the other side of the dielectric substrate.

[0033] The antenna 11 is preferably installed inside the terminal box 51, as shown in Figure 2, in order to minimize the influence of external noise, moisture, dust, ambient temperature, etc., on the received signal. Installing the antenna 11 inside the terminal box 51 suppresses electromagnetic noise from outside the motor 41 from reaching the antenna 11. The terminal box 51 also prevents moisture, dust, etc., contained in the air outside the motor 41 from coming into contact with the antenna 11. When the motor 41 is energized, the rotor 45 and stator 49 generate heat, causing the temperature of the air inside the frame 40 to rise. However, by installing the antenna 11 inside the terminal box 51, fluctuations in the received signal generated by the antenna 11 due to the rise in ambient temperature are suppressed.

[0034] Antenna 11 is mounted on the inner surface of the terminal box 51 with the surface of the dielectric substrate on which the radiating element is formed facing the stator coil 42, in other words, with the surface on which the antenna element is formed facing in the negative Z-axis direction. When antenna 11 receives electromagnetic waves in the microwave frequency band generated by partial discharge, it generates a received signal and sends the received signal to the signal processing unit 12 shown in Figure 1.

[0035] The signal processing unit 12 performs signal processing on the received signal acquired from the antenna 11, including noise reduction using a BPF (Band Pass Filter), A / D (Analog / Digital) conversion, and detection. Then, the signal processing unit 12 samples the received signal at predetermined sampling intervals, for example, every 0.4 milliseconds, to generate sampling data indicating the signal strength of the received signal. The signal processing unit 12 sends the generated sampling data to the score determination unit 13.

[0036] The score determination unit 13 obtains a score indicating the strength of the signal intensity over the detection period from the sampling data generated by the signal processing unit 12 during the detection period, which includes multiple sampling periods. The length of the detection period is, for example, 5 seconds. The score determination unit 13 sends the determined score to the degradation discrimination unit 14.

[0037] The deterioration detection unit 14 determines whether or not the insulating material of the electric motor 41 is deteriorated by comparing it with a score reference value determined according to the possible values ​​that the signal strength of the received signal can take when the insulating material of the electric motor 41 is deteriorated. The deterioration detection unit 14 transmits the determination result to the output device 20.

[0038] The output device 20 is installed, for example, in the driver's cab or on ground equipment. The output device 20 installed in the driver's cab is a display device connected to the deterioration diagnosis device 1 via the in-vehicle network, and displays the determination results obtained from the deterioration determination unit 14 on the screen. An example of an output device 20 installed in a control center, which is on ground equipment, is connected to the deterioration diagnosis device 1 via the in-vehicle network and the internet. The output device 20 displays the determination results obtained from the deterioration determination unit 14 on the screen, or transmits them to other equipment installed in the control center, for example, a condition monitoring and maintenance device that estimates signs of failure of on-board equipment.

[0039] Figure 11 shows the hardware configuration of the control processing unit, specifically the signal processing unit 12, the score determination unit 13, and the degradation discrimination unit 14, of the degradation diagnostic device 1 having the above configuration. The degradation diagnostic device 1 includes a processor 91, a memory 92, and an interface 93. The processor 91, the memory 92, and the interface 93 are connected to each other by a bus 90. The functions of the signal processing unit 12, the score determination unit 13, and the degradation discrimination unit 14 are realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in the memory 92. The functions of each of the above-mentioned units are realized by the processor 91 reading and executing the programs stored in the memory 92. That is, the memory 92 stores programs for executing the processing of the signal processing unit 12, the score determination unit 13, and the degradation discrimination unit 14.

[0040] Memory 92 includes, for example, non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read-Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (Electrically Erasable and Programmable Read-Only Memory), as well as magnetic disks, flexible disks, optical disks, compact disks, minidiscs, DVDs (Digital Versatile Discs), etc.

[0041] The degradation diagnostic device 1 is connected to the output device 20 via interface 93. Interface 93 has one or more interface modules compliant with standards, depending on the connection destination.

[0042] The operation of the degradation diagnosis device 1 having the above configuration will be described below. When the power converter 31 starts operating, the degradation diagnosis device 1 starts the degradation diagnosis process shown in Figure 12. For example, the degradation diagnosis device 1 obtains the U-phase voltage command value from the control device that controls the power converter 31, and when it detects the rising edge of the U-phase voltage command value, it starts the degradation diagnosis process.

[0043] The signal processing unit 12 samples the received signal at predetermined sampling intervals and generates sampling data indicating the signal strength of the received signal (step S11). The signal strength indicated by the sampling data has variations, as shown in Figures 13 and 14. Figure 13 is a diagram showing the variation in signal strength for each phase. The horizontal axis of Figure 13 shows the phase (unit: degrees), and the vertical axis shows the signal strength (unit: dBm). The target range of signal strength is the intensity target range, for example, when the signal strength is 10 -9 Greater than mW, and 10 -5In Figure 13, the range where the signal strength is less than or equal to mW is represented as the range where the signal strength is greater than -90 dBm and less than or equal to -50 dBm. The target strength range should be determined according to the values ​​that the signal strength of the received signal generated by the antenna 11 can take when the insulating material of the motor 41 is deteriorating. The phase shown on the horizontal axis is the phase corresponding to the detected signal strength, with the phase of the U-phase voltage as the reference.

[0044] Figure 14 shows the frequency of occurrence of signal intensity. The vertical axis of Figure 14 represents signal intensity (unit: dBm), and the horizontal axis of Figure 14 represents the number of sampled data points with each signal intensity. In the example in Figure 14, the mode of signal intensity is -76 dBm.

[0045] As mentioned above, there is variation in signal strength, but when the insulating material deteriorates, the signal strength indicated by each sampled data generated over the detection period tends to increase. Therefore, as shown in Figure 12, the score determination unit 13 obtains a score indicating the strength of the signal from the sampled data generated by the signal processing unit 12 during the detection period (step S12).

[0046] For example, the score determination unit 13 uses the sum of the products of intensity reference values, which are determined at regular intervals within the intensity target range, and the number of sampled data points whose signal intensity corresponds to the intensity reference value, as a score indicating the strength of the signal intensity.

[0047] In detail, the score determination unit 13, as shown in Figure 15, pre-stores intensity reference ranges and intensity reference values ​​corresponding to those ranges. The intensity reference range is, for example, an intensity range with a width equivalent to 5 dBm and expressed in units of mW. The intensity reference value is expressed in mW. The score determination unit 13 counts the number of sampled data included in each intensity reference range. In the example in Figure 15, the number of sampled data where the signal intensity S is greater than S1 and less than or equal to S2 is D2. The intensity reference value corresponding to the intensity reference range where the signal intensity S is greater than S1 and less than or equal to S2 is B2. The score determination unit 13 calculates a score Sc, which is the sum of the product of the intensity reference value and the number of sampled data where the signal intensity corresponds to the intensity reference value, as expressed by equation (1) below.

[0048]

number

[0049] Even if the received signal contains noise greater than, for example, -90 dBm but less than or equal to -82 dBm, the signal strength of the noise, expressed in mW, is sufficiently low, and therefore has little impact on the score. By performing a degradation diagnosis of the insulating material based on the score obtained as described above, it becomes possible to perform a degradation diagnosis with high accuracy.

[0050] In Embodiment 1, the score determination unit 13 calculates a score for each detection period as described above. The score determination unit 13 further calculates the average value of the scores over multiple detection periods. The score determination unit 13 sends the score obtained in the most recent detection period and the average value of the scores over multiple detection periods prior to that period to the deterioration discrimination unit 14. Preferably, the average value of the scores is a moving average of the scores. For example, the average value of the scores obtained in the five preceding detection periods, with the most recent detection period as the reference, may be used as the average value of the scores.

[0051] As shown in Figure 12, the deterioration discrimination unit 14 determines whether or not the insulating material has deteriorated by comparing the score reference value with the score obtained from the score determination unit 13 (step S13). The deterioration discrimination unit 14 transmits the discrimination result to the output device 20 (step S14).

[0052] In detail, the degradation discrimination unit 14 determines whether or not the insulating material has deteriorated by comparing the score with a score reference value. The degradation discrimination unit 14 has a score reference value stored in advance. The score reference value is determined according to the value that the signal strength of the received signal can take when the insulating material is deteriorated. In detail, the score reference value can be determined by an accelerated degradation test. An accelerated degradation test is a test that applies higher heat, vibration, voltage, etc. to the motor 41 than during normal operation to achieve dielectric breakdown of the motor 41 in a short time.

[0053] Figure 16 shows the relationship between the service life of the electric motor 41 and the score determined by the score determination unit 13 of the degradation diagnostic device 1. The horizontal axis of Figure 16 represents the service life of the electric motor 41. The vertical axis of Figure 16 represents the score. As the service life of the electric motor 41 increases, the score increases. In an accelerated degradation test in which the electric motor 41 is intentionally subjected to repeated heating degradation, the score of the electric motor 41 is determined by the score determination unit 13 each time heating degradation occurs. By plotting the cumulative degradation time of the accelerated degradation test on the horizontal axis and the score of the electric motor 41 on the vertical axis, an approximation line showing the relationship between the cumulative degradation time and the score in the accelerated degradation test can be obtained. By continuing the heating degradation until dielectric breakdown occurs in the electric motor 41, the dielectric breakdown score, which is the score at the time of dielectric breakdown, can be obtained. The dielectric breakdown score is a common index for multiple electric motors 41 of the same design. It is preferable to perform the accelerated degradation test on multiple electric motors 41 and use the average value of the score at the time of dielectric breakdown for each electric motor 41 as the dielectric breakdown score. A value lower than this dielectric breakdown score, for example, the dielectric breakdown score obtained by an accelerated degradation test multiplied by 0.8, is used as the score reference value. The degradation discrimination unit 14 uses the same score reference value for multiple motors 41 of the same design.

[0054] During operation of the electric motors 41, the score determination unit 13 calculates the score of each electric motor 41 as described above, and the score and operating period of each electric motor 41 are stored. An example of the relationship between the operating period and score of the electric motors 41 is plotted in Figure 16. From the plotting results, an approximation line L1 is obtained, which shows the relationship between the operating period and score of the electric motors 41, indicated by a dashed line in Figure 16. From the approximation line L1, it is possible to determine the remaining lifespan Δt, which is the time remaining until dielectric breakdown occurs in the electric motor 41, and the operating time Δt', which is the time remaining until the score of the electric motor 41 reaches the score threshold value. If the operating pattern of the railway vehicle on which the electric motors 41 are installed is constant, or if the operating period of the electric motors 41 is the net operating time, i.e., the running time of the railway vehicle, the remaining lifespan Δt and operating time Δt' can be determined with greater accuracy.

[0055] To improve the accuracy of deterioration detection, it is preferable that the deterioration detection unit 14 determines whether the score obtained from the score determination unit 13 is within the appropriate score range, and determines whether or not the insulating material has deteriorated when the score is within the appropriate score range.

[0056] When a score is obtained for multiple electric motors 41 using the degradation diagnostic device 1, the score value changes according to the degree of degradation of the insulating material of each electric motor 41, as shown in Figure 17. The vertical axis of Figure 17 shows the average, maximum, and minimum scores for each electric motor 41. The average score of the electric motor 41 with the most degraded insulating material is Sc1. avg As shown, the maximum score of the electric motor 41 is Sc1 max As shown, the minimum score of the electric motor 41 is Sc1 min This is shown.

[0057] As shown in Figure 17, the ratio of the maximum or minimum score to the average score does not change significantly even if the degree of deterioration of the insulating material of the motor differs. Therefore, the appropriate score range can be determined from the ratio of the maximum and minimum scores to the average score, as well as from the average score.

[0058] As shown in Figure 18, an approximation line L2 is obtained from the relationship between the average score and the maximum score of each motor 41. By using the approximation line L2, it is possible to estimate the maximum score from the average score obtained by the score determination unit 13. Similarly, by using the approximation line obtained from the relationship between the average score and the minimum score of each motor 41, it is possible to estimate the minimum score from the average score obtained by the score determination unit 13. The deterioration discrimination unit 14 estimates the maximum and minimum scores from the average score obtained from the score determination unit 13 as described above, and determines the appropriate score range that includes the estimated maximum and minimum scores. The deterioration discrimination unit 14 is assumed to have formulas, correspondence tables, etc., stored in advance for determining the appropriate score range from the average score.

[0059] As shown in Figure 19, the appropriate score range can be determined from the approximation line L2 obtained from the relationship between the average score and the maximum score of each motor 41, and the approximation line L3 obtained from the relationship between the average score and the minimum score of each motor 41. The degradation discrimination unit 14 determines the appropriate score range from the average score obtained from the score determination unit 13 and the equations of the approximation lines L2 and L3. In detail, if the average score obtained from the score determination unit 13 is 30, the degradation discrimination unit 14 uses the appropriate score range R1 shown in Figure 19 as the appropriate score range.

[0060] The degradation discrimination unit 14 determines whether the score obtained from the score determination unit 13 for the most recent detection period falls within the appropriate score range R1. In the example in Figure 19, scores Sc2 and Sc3 are not within the appropriate score range R1. Specifically, score Sc2 is greater than the upper limit of the appropriate score range R1, and score Sc3 is less than the lower limit of the appropriate score range R1.

[0061] If the score is not within the appropriate score range, it can be assumed that there is an abnormality in the received signal generated by the antenna 11, for example, due to the influence of external noise, poor power supply to the antenna 11, or a malfunction of the antenna 11. The degradation detection unit 14 does not perform degradation detection if the score obtained from the score determination unit 13 is not within the appropriate score range.

[0062] In the example shown in Figure 19, the score Sc4 falls within the appropriate score range R1. When the score obtained from the score determination unit 13 is within the appropriate score range, the deterioration determination unit 14 determines whether or not the insulating material of the motor 41 has deteriorated by comparing the score with the score reference value.

[0063] If the score is below the score threshold, it can be assumed that there is no deterioration of the insulating material of the motor 41. If the score is greater than the score threshold, it can be assumed that there is deterioration of the insulating material of the motor 41. Since the score Sc4 is within the appropriate score range R1 and is smaller than the score threshold, the deterioration determination unit 14 determines that there is no deterioration of the insulating material of the motor 41 and sends the determination result to the output device 20.

[0064] If the electric motor 41 continues to be used, the amplitude of electromagnetic waves caused by partial discharge will increase due to the expansion of voids 65a, the occurrence of cracks 65b, etc. As a result, the average value of the score determined by the score determination unit 13 will increase. When the average value of the score increases, the upper and lower limits of the appropriate score range will increase. For example, if the average value of the score obtained from the score determination unit 13 is 50, the degradation discrimination unit 14 will use the appropriate score range R2 shown in Figure 19 as the appropriate score range.

[0065] Since score Sc5 falls within the appropriate score range R2 and is smaller than the score reference value, the deterioration discrimination unit 14 determines that there is no deterioration of the insulating material of the electric motor 41 and sends the discrimination result to the output device 20.

[0066] Score Sc6 falls within the appropriate score range R2, but is greater than the score reference value. In this case, the deterioration discrimination unit 14 determines that deterioration has occurred in the insulating material of the electric motor 41 because score Sc6 is greater than the score reference value, and sends the discrimination result to the output device 20.

[0067] Once the processing in step S14 is complete, the degradation diagnosis device 1 repeats the processing from step S11. While the power converter 31 is operating and power is being supplied to the electric motor 41, the degradation diagnosis device 1 repeats the degradation diagnosis process.

[0068] When the output device 20 obtains a determination result from the deterioration determination unit 14 of the deterioration diagnosis device 1, it displays it on the display device in the driver's cab.

[0069] As described above, according to the deterioration diagnosis device 1 of Embodiment 1, the deterioration discrimination unit 14 determines whether or not the insulating material of the electric motor 41 has deteriorated by comparing a score reference value with a score indicating the strength of sampling data indicating the signal strength of the received signal generated by the antenna 11. Therefore, it is possible to determine whether or not the insulating material of the electric motor 41 has deteriorated while the electric motor 41 is attached to a vehicle.

[0070] The deterioration discrimination unit 14 determines whether or not the insulating material has deteriorated by comparing the score with a score reference value that is lower than the estimated score at the time of dielectric breakdown, thereby enabling the detection of deterioration of the insulating material before dielectric breakdown occurs. By detecting that deterioration of the insulating material has occurred before dielectric breakdown occurs and outputting the discrimination result from the output device 20, the user can be prompted to perform maintenance work on the electric motor 41 before dielectric breakdown occurs. Dielectric breakdown of the stator coil 42 often leads to the destruction of the stator core 50, but if maintenance work can be performed before dielectric breakdown occurs, the stator core 50 can be reused.

[0071] (Embodiment 2) The number of antennas is not limited to the examples described above. The degradation diagnosis device 2 of the degradation diagnosis system 100 according to Embodiment 2 includes a plurality of antennas, specifically antennas 11a, 11b, and 11c, as shown in Figure 20. Antennas 11a, 11b, and 11c are provided for each phase of the motor 41. For example, antennas 11a, 11b, and 11c are provided according to the U phase, V phase, and W phase, respectively. Specifically, antennas 11a, 11b, and 11c are provided inside the terminal box 51 at positions adjacent to the electric wires 32a, 32b, and 32c, respectively. The structure of antennas 11a, 11b, and 11c is the same as that of antenna 11 in the degradation diagnosis device 1 according to Embodiment 1.

[0072] In addition to the configuration of the motor 41 according to Embodiment 1, the electric motor 41 includes electrostatic shielding members 54a and 54b that separate the antennas 11a, 11b, and 11c, as shown in Figure 21 and Figure 22, which is a cross-sectional view taken along the line XXII-XXII in Figure 21. The electrostatic shielding members 54a and 54b are made of a metal such as aluminum or iron.

[0073] The signal processing unit 12 samples the received signal for each phase corresponding to antennas 11a, 11b, and 11c, and generates sampled data indicating the signal strength of the received signal. In other words, the signal processing unit 12 samples the received signal acquired from antenna 11a and generates sampled data indicating the signal strength of the received signal generated by antenna 11a. Similarly, the signal processing unit 12 samples the received signal acquired from antenna 11b and generates sampled data indicating the signal strength of the received signal generated by antenna 11b. Similarly, the signal processing unit 12 samples the received signal acquired from antenna 11c and generates sampled data indicating the signal strength of the received signal generated by antenna 11c.

[0074] The score determination unit 13 determines a score indicating the strength of the sampled data for each phase corresponding to antennas 11a, 11b, and 11c. In other words, the score determination unit 13 determines the score corresponding to the U phase from the sampled data indicating the signal strength of the received signal generated by antenna 11a. Similarly, the score determination unit 13 determines the score corresponding to the V phase from the sampled data indicating the signal strength of the received signal generated by antenna 11b. Similarly, the score determination unit 13 determines the score corresponding to the W phase from the sampled data indicating the signal strength of the received signal generated by antenna 11c.

[0075] The degradation detection unit 14 determines whether or not the insulating material has deteriorated for each phase corresponding to the antennas 11a, 11b, and 11c. In other words, the degradation detection unit 14 determines whether or not the insulating material of the U-phase coil 42a has deteriorated based on the score corresponding to the U-phase. Similarly, the degradation detection unit 14 determines whether or not the insulating material of the V-phase coil 42b has deteriorated based on the score corresponding to the V-phase. Similarly, the degradation detection unit 14 determines whether or not the insulating material of the W-phase coil 42c has deteriorated based on the score corresponding to the W-phase.

[0076] As described above, the deterioration diagnostic device 2 according to Embodiment 2 makes it possible to determine whether or not the insulating material has deteriorated for each phase corresponding to the antennas 11a, 11b, and 11c.

[0077] This disclosure is not limited to the embodiments described above. The hardware configuration and flowchart described above are examples and can be changed and modified as needed.

[0078] The length of the sampling period can be determined arbitrarily. When the sampling period is not constant, in order to compensate for the difference in scores caused by the difference in sampling period, the score determination unit 13 may use as the score the product of the result of multiplying the signal intensity shown by the sampling data by a coefficient corresponding to the sampling period and the number of sampling data corresponding to the signal intensity.

[0079] The score determination unit 13 may calculate the average value of the scores over multiple detection periods, including the most recent detection period, and send this average value to the deterioration determination unit 14. In this case, if the score obtained in the most recent detection period is within the appropriate score range, the deterioration determination unit 14 can determine whether or not the insulating material has deteriorated by comparing the average value of the scores over multiple detection periods, including the most recent detection period, with the score reference value.

[0080] The method for determining the score reference value used by the degradation discrimination unit 14 is not limited to the example described above. For example, when dielectric breakdown occurs in the electric motor 41 during operation, the score obtained by the score determination unit 13 may be used as the dielectric breakdown score, and the score reference value may be determined based on the dielectric breakdown score.

[0081] The degradation discrimination unit 14 may use a warning threshold lower than the score reference value and, if the score is equal to or greater than the warning threshold, transmit a discrimination result indicating that there are signs of deterioration of the insulating material to the output device 20. The degradation discrimination unit 14 may also determine whether or not the insulating material is deteriorated or whether or not there are signs of deterioration of the insulating material based on the remaining life Δt or the usable time Δt'. The degradation discrimination unit 14 may determine the remaining life Δt or usable time Δt' from a straight line connecting a point in the plot shown in Figure 16 and the origin, and the dielectric breakdown score or score reference value. The degradation discrimination unit 14 may determine the remaining life or usable time in the accelerated degradation test from a point in the plot shown in Figure 16 and the relationship between the cumulative degradation time obtained in the accelerated degradation test and the score, and then determine the remaining life Δt or usable time Δt' by multiplying the remaining life or usable time in the accelerated degradation test by the degradation ratio Sr. The degradation ratio Sr is determined according to the Arrhenius law based on the temperature T at which the life is halved, vibration acceleration α, etc.

[0082] The method for determining the appropriate score range used by the degradation discrimination unit 14 is not limited to the example described above. In the embodiment described above, the degradation discrimination unit 14 used the range from a point on the approximation line L3 to a point on the approximation line L2 as the appropriate score range, but it may also use a range defined by a lower limit smaller than a point on the approximation line L3 and an upper limit larger than the approximation line L2 as the appropriate score range.

[0083] The control section of the degradation diagnostic devices 1 and 2 may be implemented by a processing circuit 94, as shown in Figure 23. The processing circuit 94 is connected to the output device 20 via an interface circuit 95. If the processing circuit 94 is dedicated hardware, it may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The signal processing unit 12, the score determination unit 13, and the degradation discrimination unit 14 may each be implemented by a separate processing circuit 94, or the signal processing unit 12, the score determination unit 13, and the degradation discrimination unit 14 may be implemented by a common processing circuit 94.

[0084] Some functions of the signal processing unit 12, score determination unit 13, and degradation discrimination unit 14 may be implemented by dedicated hardware, while other functions may be implemented by software or firmware. For example, in the degradation diagnostic device 1 according to Embodiment 1, the signal processing unit 12 may be implemented by the processing circuit 94 shown in Figure 23, and the score determination unit 13 and degradation discrimination unit 14 may be implemented by the processor 91 shown in Figure 11 reading and executing a program stored in memory 92.

[0085] The mounting positions of antennas 11, 11a, 11b, and 11c are not limited to the examples described above, but can be any position where electromagnetic waves generated by partial discharge can be received. For example, antennas 11a, 11b, and 11c may be installed adjacent to the U-phase coil 42a, V-phase coil 42b, and W-phase coil 42c, respectively.

[0086] The degradation diagnostic device 1 may determine whether or not the motor 41 is degraded when a voltage in phase is applied to the U-phase coil 42a, V-phase coil 42b, and W-phase coil 42c from a test power supply device (not shown). When a voltage in phase is applied to the U-phase coil 42a, V-phase coil 42b, and W-phase coil 42c, the amplitude of the radio waves received by the antenna 11 is larger than when voltages with different phases are applied to the U-phase coil 42a, V-phase coil 42b, and W-phase coil 42c. The increased amplitude reduces the influence of noise, allowing the degradation diagnostic device 1 to determine whether or not the insulating material is degraded with greater accuracy.

[0087] The deterioration diagnostic devices 1 and 2 may operate by receiving power from the current collector, similar to the power converter 31.

[0088] The configuration of the electric motor 41 is not limited to the example described above. For example, the electric motor 41 may be a frameless motor. The pair of brackets of the frameless electric motor 41 sandwich the stator core 50 in the Y-axis direction. One of the brackets has through holes through which the electric wires 32a, 32b, and 32c are inserted. The antenna 11 is provided inside the terminal box 51 that covers the through holes formed in the bracket.

[0089] As another example, the electric motor 41 does not need to have a terminal box 51. In this case, the antenna 11 can be attached to the outer surface of the bracket that sandwiches the frame 40, the stator core 50 in the Y-axis direction, the outer surface of the stator core 50, or the inner surface of the bracket, etc.

[0090] The U-phase coil 42a, the V-phase coil 42b, and the W-phase coil 42c may be connected in a delta configuration.

[0091] Antennas 11, 11a, 11b, and 11c are not limited to planar antennas, but are any directional antennas capable of receiving electromagnetic waves radiated due to partial discharges occurring in the insulating material of the electric motor 41 and suppressing interference with electromagnetic waves radiated from electric motors 41 that are not the target.

[0092] The signal processing unit 12, score determination unit 13, and deterioration discrimination unit 14 of the deterioration diagnosis devices 1 and 2 may be implemented as a function of a train information management system. Parts of the deterioration diagnosis devices 1 and 2 may be mounted on a vehicle, while other parts are installed on the ground. For example, the antenna 11 and signal processing unit 12 of the deterioration diagnosis device 1 may be mounted on a vehicle, while the score determination unit 13 and deterioration discrimination unit 14 of the deterioration diagnosis device 1 may be located in a control center. In this case, the signal processing unit 12 and the score determination unit 13 each only need to have a communication function that allows them to communicate with each other.

[0093] The degradation diagnostic devices 1 and 2 that perform the above-described operations may be realized by distributing a computer-readable recording medium such as a flexible disk, CD-ROM (Compact Disc - Read Only Memory), or DVD-ROM (Digital Versatile Disc - Read Only Memory) containing a computer program for performing the above-described operations, and then installing the computer program on a computer. Alternatively, the degradation diagnostic devices 1 and 2 that perform the above-described operations may be realized by a dedicated system. The computer program may be superimposed on a carrier wave and provided via a communication network.

[0094] The power converter 31 is not limited to DC-powered railway vehicles, but can be installed in any vehicle, including AC-powered railway vehicles and railway vehicles equipped with internal combustion engines.

[0095] The motor 41 may be either a three-phase induction motor or a three-phase synchronous motor. Furthermore, the motor 41 is not limited to a three-phase motor; for example, it may be a single-phase motor or a DC motor. The motor 41 may be an inner rotor or an outer rotor.

[0096] This disclosure allows for various embodiments and modifications without departing from the broad spirit and scope of this disclosure. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of this disclosure. In other words, the scope of this disclosure is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the equivalent significance of the disclosure are considered to be within the scope of this disclosure. [Explanation of Symbols]

[0097] 1,2 Degradation diagnostic device, 11,11a,11b,11c Antenna, 12 Signal processing unit, 13 Score determination unit, 14 Degradation discrimination unit, 20 Output device, 31 Power converter, 32a,32b,32c Electric wire, 40 Frame, 40a Through hole, 41 Electric motor, 42 Stator coil, 42a U-phase coil, 42b V-phase coil, 42c W-phase coil, 43 Shaft, 44 Bearing, 45 Rotor, 46 Rotor core, 47 Conductor bar, 48 Short-circuit ring, 49 Stator, 50 Stator core, 50a Slot, 51 Terminal box, 52 Inter-coil insulating member, 53 Wedge, 54a,54b Electrostatic shielding member, 61 Strand wire, 62 Conductor, 63 Insulating coating member, 64 Insulating tape, 65 Insulating varnish, 65a Void, 65b crack, 90 bus, 91 processor, 92 memory, 93 interface, 94 processing circuit, 95 interface circuit, 100 degradation diagnostic system, AX rotation axis, L1, L2, L3 approximation lines, R1, R2 score appropriate range, Δt remaining life, Δt' operational time.

Claims

1. An antenna that receives electromagnetic waves in the microwave frequency band radiated due to partial discharge occurring in the insulating material of an electric motor and generates a received signal, A signal processing unit that samples the received signal at each sampling period and generates sampling data indicating the signal strength of the received signal, A score determination unit that obtains a score indicating the strength of the signal intensity over the detection period from the sampling data generated by the signal processing unit during a detection period including multiple sampling periods, A deterioration determination unit determines, based on the relationship between the service life of the motor and the score, the remaining lifespan, which is the time remaining until dielectric breakdown of the motor occurs, or the operating time, which is the time remaining until the score of the motor reaches a score reference value determined according to the value that the signal strength can take when the insulating material is deteriorated, and determines whether or not the insulating material is deteriorated or whether or not there are signs of deterioration of the insulating material, based on the remaining lifespan or the operating time. A deterioration diagnostic device equipped with the following features.

2. The deterioration determination unit determines whether or not the insulating member has deteriorated based on the remaining lifespan, or the operating time, which is the remaining time until the score of the motor reaches the score reference value determined based on the score breakdown score, which is the score obtained by the score determination unit when the insulating member deteriorates and dielectric breakdown occurs. The deterioration diagnostic device according to claim 1.

3. The deterioration determination unit uses the relationship between the service life of the motor and the score, and the dielectric breakdown score or the score reference value which is the score obtained by the score determination unit when the insulating member deteriorates and dielectric breakdown occurs, or the remaining life or the operational time which is determined from the relationship between the service life of the motor and the score, and the cumulative deterioration time obtained in the accelerated deterioration test and the score. A deterioration diagnostic device according to claim 1 or 2.

4. The antenna is installed inside the terminal box of the motor, through which wires are routed from the outside of the motor to the stator coil inside the motor. A deterioration diagnostic device according to claim 1 or 2.

5. The aforementioned motor is a three-phase motor, The deterioration diagnostic device determines whether or not the insulating member of the motor has deteriorated when a voltage of the same phase is applied to each coil of the motor. A deterioration diagnostic device according to claim 1 or 2.

6. The motor is a three-phase motor, and each of the antennas is provided at a position separated by an electrostatic shielding member, corresponding to the respective phases of the motor. The signal processing unit generates the sampling data for each phase corresponding to the antenna, The score determination unit determines the score for each phase to which the antenna corresponds, The deterioration detection unit determines whether or not the insulating member has deteriorated for each phase of the antenna. A deterioration diagnostic device according to claim 1 or 2.

7. A deterioration diagnostic device according to claim 1 or 2 for determining whether or not the insulating member of the electric motor has deteriorated, An output device that acquires the determination result of the deterioration determination unit of the deterioration diagnostic device and outputs the acquired determination result, A deterioration diagnosis system equipped with the following features.

8. The received signal generated by an antenna that receives electromagnetic waves in the microwave frequency band radiated due to partial discharge occurring in the insulating material of an electric motor is sampled at each sampling period to generate sampling data indicating the signal strength of the received signal. From the sampling data during a detection period that includes multiple sampling periods, a score indicating the strength of the signal intensity over the detection period is obtained. Based on the relationship between the service life of the electric motor and the score, the remaining lifespan, which is the time remaining until dielectric breakdown of the electric motor occurs, or the operating time, which is the time remaining until the score of the electric motor reaches a score reference value determined according to the value that the signal intensity can take when the insulating material is degraded, is determined, and based on the remaining lifespan or the operating time, it is determined whether or not the insulating material is degraded or whether or not there are signs of deterioration of the insulating material. Methods for diagnosing deterioration.

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