JP5113919B2 - Inspection drive diagnosis method for inverter drive motor - Google Patents

Description

  The present invention relates to an inspection diagnosis method for an inverter drive motor.

  In recent years, from the viewpoint of energy saving and high efficiency, it has been actively practiced to operate a motor at a variable speed using an inverter power supply. By the way, since the voltage applied to the motor from the inverter power supply is a pulse voltage (hereinafter referred to as inverter pulse voltage), the evaluation of the insulation performance of the motor insulating material needs to consider the pulse voltage.

  However, although the insulation evaluation data, design method, inspection method, and diagnosis method for motor insulation materials for sine waves have been established, the insulation evaluation data, design method, inspection method, and diagnosis method for inverter pulse voltage have not necessarily been established. At present, intensive studies are being conducted in various fields. For example, Non-Patent Document 1 introduces evaluation of partial discharge characteristics of an insulating material under an inverter pulse voltage.

  Patent Document 1 proposes a method for estimating the lifetime of an insulating material under an inverter pulse voltage based on conventionally accumulated sinusoidal insulation lifetime data. According to this, it is considered that the insulation degradation accompanying the inverter pulse voltage is the most important voltage parameter. Also, since the rise time of the inverter pulse voltage is shorter than the sine wave voltage, the partial discharge start voltage increases, and the life characteristic of the insulator shifts to the high voltage side compared to the sine wave by the increase of the partial discharge start voltage. I think so.

Japanese Patent Laid-Open No. 9-80006

IEEJ Technical Report No. 739, p. 22-29, August 1999

  However, in evaluating the insulation performance against the inverter pulse voltage, in addition to the rise time of the inverter pulse voltage, various voltages such as the fall time of the inverter pulse voltage, pulse width, unipolar / bipolar, presence / absence of polarity reversal, frequency, etc. Parameters are relevant. Nonetheless, in conventional insulation evaluation, the voltage parameters are different for each study, so it is not always clear which voltage parameters affect the partial discharge characteristics, and how it is applied to actual products. It was unclear whether it could be applied. For this reason, the conventional measurement results cannot always be immediately reflected in the insulation design, inspection, and diagnosis of the inverter drive motor.

  Assuming one or more voltage parameters that are considered to have the greatest influence on the deterioration of insulation caused by inverter pulse voltage among the voltage parameters, the insulation characteristics of the insulation material and the motor, especially the life of the insulation material and the motor, are assumed. If measured, it takes a long test time, and it is difficult to apply it to the design of inverter drive motors that have been widely used in recent years.

  Moreover, even if the inverter pulse voltage with the same rise time is applied in the actual field even if the inverter pulse voltage is evaluated as in the prior art of Patent Document 1, it is insulated from the motor that causes dielectric breakdown in the actual field. There are motors that do not break down. Therefore, it is not always possible to evaluate the motor insulation life by focusing only on the rise time of the inverter pulse voltage.

  For these reasons, at least for inverter-driven motors, not only evaluate the life of the insulation material against the inverter pulse voltage observed at the motor terminal, but also examine the voltage waveform and insulation characteristics inside the motor equipment to evaluate and design the insulation. It may be necessary to perform examination and diagnosis.

  Therefore, in view of the state of the prior art, an object of the present invention is to establish an insulation evaluation method for an inverter drive motor and provide an inspection diagnosis method.

  First, an insulation evaluation method for an inverter drive motor according to the present invention will be described. Basically, a bipolar voltage having a peak voltage Vm, a pulse width tw, and a frequency fp generated between winding turns of the inverter drive motor is used as a test voltage, and the test voltage is continuously applied to the sample insulating material. The life time tp until the sample insulation material breaks down is measured, and the relationship between the peak voltage Vm and the life time tp is obtained as the insulation life property of the sample insulation material. The insulating performance of the sample insulating material is evaluated based on the above.

  That is, when an inverter surge voltage applied to the motor is applied to the motor winding, the surge voltage becomes a voltage wave that propagates through the motor winding. At this time, due to the propagation delay when propagating from the winding start to the winding end of the motor winding, a large surge voltage is shared between winding turns of the same winding. When the voltage applied to the motor winding is a sine wave, the rise time of the voltage is longer than the surge propagation time of the winding, so there is no propagation delay and the sine wave voltage is evenly distributed between each winding turn. Be shared. However, in the case of a surge voltage with a steep rise, even if a surge voltage wave has reached the turn on the lead side of the winding, a state in which the surge voltage wave has not reached the internal turn occurs. A large voltage is generated between line turns. In general, the insulation between the winding turns is about 1/10 of the thickness of the ground insulation that insulates the winding and the core. In an inverter drive motor, the insulation between the winding turns is the strictest. Further, when the voltage generated between the winding turns when the inverter surge voltage is applied to the motor winding is measured, a bipolar alternating pulse voltage having a narrow pulse width is generated between the winding turns.

  Therefore, in the insulation evaluation according to the present invention, the sample insulating material is obtained by using, as the test voltage, the bipolar alternating pulse voltage having the peak voltage Vm, the pulse width tw, and the frequency fp of the motor winding turn sharing voltage generated between the winding turns. Of the insulating material used for the insulation between the motor winding turns with respect to the inverter pulse voltage by measuring the life time tp of the sample and obtaining the change in the life time tp with respect to the peak voltage Vm as the insulating life characteristic of the sample insulating material. Evaluate performance.

As another aspect of the insulation evaluation method according to the present invention, a bipolar voltage pulse having a peak voltage Vm, a pulse width tw, and a frequency fp generated between winding turns of an inverter drive motor is used as a test voltage. A voltage is applied to the sample insulating material to measure the partial discharge occurrence frequency Np per cycle of the bipolar alternating pulse voltage, and a sine wave voltage of the frequency fp having the peak voltage Vm is applied to the sample insulating material. The partial discharge occurrence frequency Ns per cycle of the sinusoidal voltage and the life time ts until the sample insulating material breaks down were measured, and the bipolar alternating pulse voltage was applied to the sample insulating material. The life time tp until the sample insulation material breaks down is estimated by the following equation (1),
tp = (Ns / Np) · ts (1)
Obtaining the relationship between the estimated life time tp and the peak voltage Vm as the insulation life characteristic of the sample insulation material, and evaluating the insulation performance of the sample insulation material based on the obtained insulation life characteristic. Features.

  That is, in the measurement of the time until dielectric breakdown, the life becomes long in the low voltage region, and the measurement of the life time until the dielectric breakdown may take a long time. In this respect, the life time ts until the breakdown of the sine wave voltage for the same insulating material sample is relatively short as compared with the pulse voltage having a narrow pulse width. Therefore, the life time ts of the sine wave voltage in the low voltage / long life region. Tp can be estimated from the above equation (1). In other words, the above equation (1) means that the lifetime ts measured with the sinusoidal test voltage is shifted by (Ns / Np) to obtain the insulation lifetime characteristics under the bipolar alternating pulse voltage. In addition, if the data of the lifetime of sine wave voltage ts have the data measured in the past about the same insulating material sample, the past measurement data can be used.

  As described above, according to the insulation evaluation method according to the present invention, when the inverter surge voltage is applied, the portion of the insulating material using the narrow bipolar repetitive alternating pulse voltage generated between the motor winding turns is used. Since the discharge characteristics and the insulation life characteristics are evaluated, it is possible to accurately evaluate and design the insulating material between the winding turns of the inverter drive motor. In particular, since attention is paid to the frequency of occurrence of partial discharge and the insulation life time under a narrow pulse voltage, high-precision insulation life characteristics between the motor winding turns can be obtained.

The inspection and diagnosis method for an inverter drive motor according to the present invention that solves the above problems can be realized by applying the above-described insulation evaluation method according to the present invention. That is, the relationship between the peak voltage Vm per cycle of the bipolar alternating pulse voltage having the peak voltage Vm, the pulse width tw, and the frequency fp and the partial discharge occurrence frequency Np, and the peak voltage Vm between the motor winding turns and the insulation life Prepare relational data of time tp, convert Vm of these relational data into surge voltage of magnitude ΔV necessary to apply the voltage between winding turns of target motor, and insulate life of standard product motor Set as a characteristic. Next, the magnitude ΔV of the surge voltage to ground at the motor terminal, the rise time tr, the pulse voltage of the frequency fp or the pulse voltage of the actual inverter power supply is applied to the inspection object, and the portion of the pulse voltage per one surge voltage cycle The discharge occurrence frequency Nx is measured. Based on the measured partial discharge occurrence frequency Nx and the insulation life characteristics of the standard motor, the insulation life time tp and the partial discharge occurrence frequency Np when the surge voltage magnitude ΔV is applied are obtained by the following formula ( According to 2), the insulation life time tx to be inspected is obtained, and the insulation to be inspected is inspected by comparing the obtained insulation life time tx with the set required life time.
tx = (Np / Nx) · tp (2)

  The insulation life characteristic of the product to be inspected is created by shifting the insulation life characteristic of the standard product by (Np / Nx). In the insulation life characteristic (ΔV-tx) of the obtained product to be inspected, if the insulation life time tx is longer than the required life, the product is accepted and shipped.

  On the other hand, if it becomes a defective product, consider whether the motor-side surge voltage magnitude ΔV of the inverter drive motor can be reduced or the rise time tr can be increased, and if possible, the specifications are limited. Ship as acceptable. When the motor end surge voltage is a vibration waveform, a surge voltage reflecting the vibration frequency and attenuation time constant is applied to the motor.

  In particular, when the pulse rise time of the inverter pulse test power supply used when inspecting or diagnosing the motor is different from the rise time of the surge voltage observed at the motor terminal to be inspected and diagnosed when the inverter is driven, It is desirable to increase or decrease the magnitude ΔV of the surge voltage of the inverter pulse test power source by a value necessary for applying the peak voltage Vm generated when the inverter is driven.

  As described above, according to the method for inspecting and diagnosing an inverter drive motor according to the present invention, partial discharge occurrence frequency and insulation life characteristics are measured for each product to be inspected, thereby preventing shipment of defective products having a short life. it can. In addition, it is possible to improve the accuracy of estimating the service life of products by continuing to apply power to dielectric breakdown until breakdown, and to search for and identify defective locations and eliminate the causes of defects in materials and production processes. it can.

  In addition, the method for inspecting and diagnosing an inverter-driven motor according to the present invention is a part in which a sample insulating material obtained by applying a bipolar alternating pulse voltage having a peak voltage Vm, a pulse width tw, and a frequency fp reaches breakdown. Prepare the change data of discharge signal strength over time and insulation life characteristics, and convert Vm into surge voltage of magnitude ΔV necessary to apply this voltage between winding turns of the target motor. Are set as the time-dependent data of the partial discharge signal intensity and the insulation life characteristics of the motor.

  Next, for the product of the inverter drive motor to be diagnosed (hereinafter referred to as a field product), a margin time x that is recommended to replace the device before dielectric breakdown is determined. On the other hand, in the time-dependent change data of the partial discharge signal intensity of the standard product, the partial discharge signal intensity x years before the insulation life tp is obtained, and this is set as the threshold value θth of the partial discharge signal intensity for product replacement. Then, the partial discharge of the field product is measured constantly or periodically, and this is compared with the threshold value θth of the partial discharge signal intensity. If the partial discharge signal intensity exceeds the threshold value θth, the product is replaced with a new one. .

  As described above, according to the inspection and diagnosis method for field products of the present invention, insulation deterioration diagnosis and pre-failure part replacement are performed based on the temporal change in partial discharge signal intensity obtained by accurate evaluation of the insulating material between winding turns. Therefore, field product failures can be prevented. In addition, by observing the degradation status of field-degraded products and the location of the breakdown when continuously applying power and causing dielectric breakdown, the cause of the degradation is identified to develop motor materials, design and production technologies that are resistant to degradation. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, the insulation evaluation method of an inverter drive motor can be established and the test | inspection diagnostic method of an inverter drive motor is realizable.

The related conceptual diagram of the insulation evaluation method between the winding turns of the inverter drive motor of the present invention, the insulation design method, the production, the insulation inspection method, and the maintenance diagnosis method is shown. The block diagram of one Example of the insulation evaluation apparatus of the inverter drive motor of this invention is shown. The flowchart of the insulation evaluation method implemented with the insulation evaluation apparatus of FIG. 2 is shown. It is a figure which shows an example of a specific structure of the test power supply part of FIG. It is a figure which shows the other example of the concrete structure of the test power supply part of FIG. It is a figure which shows an example of the circuit structure of the partial discharge measurement part of FIG. The block diagram of one Example of the product insulation test | inspection apparatus of the inverter drive motor of this invention is shown. It is a flowchart of the insulation test | inspection method implemented with the product insulation lifetime test | inspection apparatus of FIG. It is a figure which shows the structure of the 1st example of the test power supply part of the product insulation lifetime inspection apparatus of FIG. It is a figure which shows the structure of the 2nd example of the test power supply part of the product insulation lifetime inspection apparatus of FIG. It is a figure which shows the structure of the 3rd example of the test power supply part of the product insulation lifetime inspection apparatus of FIG. It is a figure which shows the structure of the 4th example of the test power supply part of the product insulation lifetime inspection apparatus of FIG. It is a figure which shows an example of the partial discharge measuring circuit of the product insulation lifetime inspection apparatus of FIG. It is a figure which shows the circuit structural example of the UVW automatic changeover switch unit of the product insulation lifetime test | inspection apparatus of FIG. It is a figure which shows the example which incorporated the actual inverter power supply in the test power supply and partial discharge measurement part of the product insulation lifetime inspection apparatus of FIG. It is a block diagram of one Example of the diagnostic apparatus of the inverter drive motor of this invention. It is a figure which shows the diagnostic flow of the diagnostic apparatus of FIG. It is a figure which shows the measurement data explaining the effect of the insulation evaluation method etc. between the winding turns of the inverter drive motor of this invention. It is explanatory drawing of the model of a spark discharge delay when a pulse voltage is applied to air.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a related conceptual diagram of an insulation evaluation method, insulation design method, production, insulation inspection method, and maintenance diagnosis method between winding turns of an inverter drive motor of the present invention. As shown in FIG. 1, as a manufacturing flow of a motor product, materials are first evaluated, and the product is designed and produced based on the obtained data. Each manufactured product is quality-inspected and shipped. The shipped product is diagnosed for insulation deterioration at all times or periodically, and if there is any sign of deterioration leading to insulation breakdown, the product or product parts are replaced before failure. At each stage of these product flows, insulation evaluation of insulating materials and products is required.

  Here, the insulation evaluation of the inverter drive motor according to the feature of the present invention is performed by the evaluation method and apparatus shown in FIGS. Moreover, the insulation test of the inverter drive motor is performed by the inspection method and apparatus shown in FIGS. Furthermore, the insulation deterioration diagnosis of the inverter drive motor and the pre-failure part replacement are performed by the diagnosis method and apparatus shown in FIGS. In each method and apparatus, evaluation results of insulating materials and processes and data necessary for improvement are measured.

  In the evaluation stage of the insulating material, measurement of insulation life-voltage characteristics, measurement of partial discharge occurrence frequency-voltage characteristics, and measurement of changes over time in partial discharge signal intensity from the initial stage to dielectric breakdown are performed.

  In addition, at the insulation inspection stage, measurement of insulation life-voltage characteristics of each product, measurement of the actual life of defective products and improvement of accuracy of product life estimation, product insulation breakdown / defect location search, and identification of the cause of failure are performed. .

  Further, in the maintenance and diagnosis stage, an evaluation necessary for insulation deterioration diagnosis and pre-failure product or product replacement is performed. For example, measurement of partial discharge deterioration characteristics of field products, measurement of remaining life of collected products, accumulation of data, search for weak spots where insulation deterioration is likely, and identification of causes are performed. These measurement data are fed back to the product manufacturing flow again, and insulation materials, design and production, inspection, diagnostic techniques, and product quality are improved at each stage or while coordinating between stages. Hereinafter, examples of each stage will be described in detail.

  With reference to FIG.2 and FIG.3, one Example of the insulation evaluation method and apparatus of the inverter drive motor of this invention is described. FIG. 2 shows the configuration of an insulation evaluation apparatus according to an embodiment of the present invention. The insulation evaluation apparatus according to this embodiment includes a test power supply unit 1, a partial discharge measurement unit 2, and a data measurement recording device 3. As the sample insulating material 4 to be evaluated, an element model simulating an insulating portion between motor winding turns is used. For example, an element model obtained by twisting insulated wires used for winding or a parallel wound wire sample is used.

  The test power supply unit 1 is configured to generate a bipolar alternating pulse voltage having a peak voltage Vm, a pulse width tw, and a frequency fp. It is desirable that the test power supply unit 1 can generate a peak voltage Vm of 0 to 15 kV or higher in peak value. Further, the pulse width tw is 5 μs or less, and it is desirable that the pulse width tw can be varied constantly or at a voltage stop in increments of 0.1 μs or less, particularly in the range of 0.1 to 1.0 μs. Further, the frequency fp is determined by the switching frequency of the inverter power supply.

  The partial discharge measuring unit 2 is a partial discharge occurrence frequency-voltage characteristic when a pulse voltage is applied to the sample insulating material 4 and a part until the sample reaches dielectric breakdown when a constant pulse voltage is applied continuously. The discharge signal strength and the insulation life time until dielectric breakdown are measured.

  The data measurement / recording device 3 controls the peak voltage Vm, pulse width tw, and frequency fp of the pulse voltage of the test power supply unit 1 via the control line 5 and at the same time the partial discharge from the partial discharge measurement unit 2 in synchronization with the test voltage. Measurement data is captured and recorded. The measurement data is plotted in a graph of partial discharge occurrence frequency-voltage characteristics, partial discharge signal intensity until dielectric breakdown, and insulation lifetime time-voltage characteristics until dielectric breakdown.

  FIG. 3 shows a flowchart of an insulation evaluation method carried out by the insulation evaluation apparatus of this embodiment.

(Step S1)
Here, the magnitude ΔV of the surge voltage to ground at the motor terminal when the motor is driven by the inverter, the rise time tr, and the frequency fp are obtained by simulation or measurement using the motor.

(Step S2)
If the process in step S1 is impossible, the process calculates the surge voltage magnitude ΔV, rise time tr, and frequency fp between the different phases by the process in step S2. This indicates that when the ground impedance of the inverter power supply and the motor is small, the ground-to-ground surge voltage almost matches the phase-to-phase surge voltage by various studies. Therefore, when the process of step S1 is impossible The interphase surge voltage is used as an alternative to the ground surge voltage.

(Step S3)
Here, the peak voltage Vm of the shared voltage generated between the motor winding turns when the obtained ground surge voltage is applied to the motor winding, the pulse width tw, and the frequency fp are simulated or measured using a motor. Ask for.

Further, by using the obtained peak voltage Vm of the motor winding turn sharing voltage and the magnitude ΔV of the surge voltage to ground, a voltage sharing ratio α (tr) used in the product inspection stage described later is expressed by the following formula ( Obtained by 3).
α (tr) = Vm / ΔV (3)
Where α (tr) is the voltage sharing ratio between the turns of the motor winding when a surge voltage with a rise time tr is applied.
Vm: Peak voltage of the shared voltage between motor winding turns
ΔV: The magnitude of the surge voltage between the grounds If it is difficult to simulate or measure the voltage shared between winding turns, it can be easily obtained as follows. That is, the peak voltage Vm of the winding turn sharing voltage is obtained by the following equation (4).
Vm = ΔV · τ / tr (4)
However, τ: Surge voltage propagation time of the motor winding portion for which deterioration due to the winding turn sharing voltage should be examined. The pulse width tw is obtained by the following equation (5).
When tr ≦ τ, tw = τ
When tr> τ, tw = tr (5)
Where τ is the surge voltage propagation time of the motor winding part that is subject to deterioration due to the shared voltage between winding turns
tr: Surge voltage rise time The pulse width tw of the pulse voltage shown in FIG. 2A can be varied in steps of 5 μs or less, particularly 0.1 μs or less in the range of 0.1 to 1.0 μs. The reason for this is that the surge voltage propagation time τ of a general motor is 5 μs at most, as a result of various measurements, in the motor winding part that should be examined for deterioration due to the shared voltage between winding turns. Generally, it was from 0.1 to 1.0 μs.

(Step S4)
Here, the data measurement and recording device 3 controls the test power supply unit 1 to create a bipolar alternating pulse voltage having the same peak voltage Vm, pulse width tw, and repetition frequency fp as the winding turn-sharing voltage, thereby insulating the sample. Electric power is applied to the material 4.

  Then, the data measuring and recording apparatus 3 controls the partial discharge measuring section 2 to measure the partial discharge occurrence frequency Np in one surge voltage cycle of the peak voltage Vm of the bipolar alternating pulse voltage, as shown in FIG. The characteristic data of the indicated peak voltage Vm−partial discharge occurrence frequency Np is acquired. Further, the partial discharge occurrence frequency Ns in one voltage cycle of the sine wave voltage of the peak voltage Vm generated in a general sine wave power supply device (not shown) is measured, and the characteristic data of the peak voltage Vm−the partial discharge occurrence frequency Ns. To get.

(Step S5)
After measuring the partial discharge characteristics in step S4, the pulse voltage and sine wave voltage of the same peak voltage Vm are continuously applied to the sample insulating material 4, and the partial discharge signal intensity Vp is set until the insulation of the sample insulating material 4 is broken. In addition to measurement, insulation lifetime times tp and ts until dielectric breakdown are measured.

  In steps S4 and S5, measurement is performed by changing the peak voltage Vm. In addition, about the partial discharge characteristic with respect to a sine wave voltage and the insulation lifetime, if there is already measured data in the past, this can be used.

  Further, in step S5, as shown in FIG. 2C, the time-dependent change in the partial discharge signal intensity Vp from the initial stage to the dielectric breakdown of the sample insulating material 4 when the peak voltage Vm is constant is measured and Record.

(Step S6)
The measurement of the insulation life time tp in step S5 is not practical in the low voltage / long life region because the time until dielectric breakdown due to the pulse voltage becomes long. Therefore, in such a low voltage region, the insulation life time ts by a sine wave voltage that can be measured in a relatively short time, the partial discharge occurrence frequency Ns at this voltage, and the partial discharge occurrence frequency Np at the time of applying the pulse voltage are used. Thus, the insulation lifetime tp is estimated from the following equation (6).
tp = (Ns / Np) · ts (6)

  By repeating the same calculation, the insulation life characteristics under the pulse voltage are shifted from the insulation life characteristics under the sine wave voltage by (Ns / Np), so that the insulation life times tp and ts shown in FIG. And the peak voltage Vm can be obtained. In this way, with respect to the sample insulating material 4, it is possible to obtain an insulating life characteristic representing a change in the insulating life time tp with respect to the peak voltage Vm.

(Steps S7 to S9)
Based on the insulation life characteristics of the sample insulating material 4 with respect to the bipolar alternating pulse voltage of the peak voltage Vm obtained in step S6, the insulation design of the inverter drive motor to be designed can be performed. That is, in step S7, based on the insulation life characteristics of the sample insulating material 4, the insulation life time tp at the peak voltage Vm of the winding winding shared voltage during actual motor driving is obtained. Next, in step S8, when the obtained insulation life time tp is longer than the required life of the motor to be designed, the process proceeds to step S9 to determine design data such as the working voltage and material specifications of the motor, Shift to product design and production process.

(Step S10)
If it is determined in step S8 that the insulation life time tp is shorter than the required life, the process proceeds to step S10, where the surge voltage magnitude ΔV is reduced or the rise time tr is slowed down to turn the winding turn. The peak voltage Vm of the shared voltage is reduced. Alternatively, the winding specifications of the motor, such as the number of turns and the winding arrangement, are changed so that the divided voltage between the motor winding turns is reduced. In addition, the insulating life time tp is extended by improving the insulating material to a material resistant to discharge deterioration, increasing the insulating thickness, or performing varnish treatment. For materials that are resistant to discharge deterioration, specifically, improvements such as increasing the amount of inorganic filler in the organic insulator can be considered. After making the improvements as described above, material evaluation will be carried out and examined again.

(Example of test power supply unit 1)
FIG. 4 shows a first example of the test power supply unit 1 of FIG. The test power supply unit 1 of this example creates a rectangular pulse voltage by alternately switching the output of the DC power supply 41 between the + side and the − side with the pulse switch 42. Further, the waveform of the pulse voltage is shaped by the high-pass filter unit 43 so as to be a bipolar alternating pulse voltage having a predetermined pulse width, and is output from the output terminal 44 to the sample insulating material 4. The pulse switch 42 uses two switching elements, positive and negative, so that the output pulse voltage is symmetrical. The DC power supply 41 and the pulse switch 42 are controlled by the data measurement / recording apparatus 3 connected to the control line 45 indicated by a broken line. In FIG. 4, the DC power supply 41 is constituted by one power supply and the-side is grounded. However, the DC power supply 41 is constituted by two DC power supplies, + and-, and the intermediate point of these series connection portions is grounded. However, a similar waveform can be obtained.

  FIG. 5 shows a second example of the test power supply unit 1. The test power supply unit 1 in this example generates a rectangular pulse voltage by turning on / off the output of the DC power supply 51 with a pulse switch 52, and further uses a high-pass filter unit 53 to generate a bipolar alternating pulse voltage with a predetermined pulse width. The waveform is shaped so as to be output from the output terminal 54 to the sample insulating material 4. The pulse switch 52 of this example is composed of one switch element. However, in this example, the output impedance 55 of the pulse switch is set to a low impedance of 100Ω or less, and when the switch element of the pulse switch 52 is cut off, a sharp negative voltage change occurs. Output pulse voltage is obtained. Note that the DC power supply 51 and the pulse switch 52 are controlled by the data measurement recording device 3 connected to the control line 55 indicated by a broken line. In FIG. 5, the DC power source 51 is composed of one power source and is grounded on the negative side. However, the DC power source 51 is composed of two DC power sources, + and −, and the intermediate point of these series connection portions is grounded. A similar waveform can be obtained.

(Example of partial discharge measuring unit 2)
FIG. 6 shows an example of a circuit configuration of the partial discharge measuring unit 2. The partial discharge measuring circuit of FIG. 6 includes a voltage measuring voltage divider 61, a coupling capacitor 62, a sample connection terminal 63, a high-frequency current probe 64, and a digital oscilloscope 65 for measuring a partial discharge current waveform. The capacitance of the coupling capacitor 62 is adjusted so as to be close to the capacitance of the sample insulating material 4 connected to the sample connection terminal 63 (indicated by a dotted line in the figure). As the high-frequency current probe 64, a wire penetration type electromagnetic coupling type current sensor is used. In particular, the connection line between the coupling capacitor 62 and the terminal 44 of the test power supply unit 1 and the connection line between the sample connection terminal 63 and the terminal 44 of the test power supply unit 1 are passed through the high-frequency current probe 64 in opposite directions. . Thereby, the charging current accompanying the pulse voltage is canceled, and only the partial discharge current generated in the sample insulating material 4 can be measured. With a pulse voltage having a short pulse width tw, partial discharge can be measured with high accuracy by canceling the charging current in this way. The high frequency current probe can be a clamp type.

  The frequency band of the high-frequency current probe 64 for measuring the partial discharge needs to be 1 MHz to 1 GHz, at least 10 MHz to 100 MHz. In the drawing, a low-voltage side connection line is used as a connection line between the coupling capacitor 62 and the sample connection terminal 63 that penetrates the current probe, but a high-voltage side connection line may be used. The partial discharge current intensity Vp, occurrence frequency, and applied voltage measured by the current probe 64 and the voltage divider 61 are measured and recorded by the digital oscilloscope 65. Further, the data is recorded in the data measurement recording device 3 connected to the control line 66. Here, it is desirable that the band of the digital oscilloscope 65 is DC to 1 GHz or more and the sampling rate is 2 GS / s or more, and at least the band is DC to 100 MHz and the sampling rate is 200 MS / s. The digital oscilloscope 65 can be replaced with an A / D card having an equivalent bandwidth, sampling speed, and data measurement memory length. In the digital oscilloscope 65 or the data measurement / recording device 3 that controls the digital oscilloscope 65, a voltage having a predetermined peak value cannot be applied to the sample, a voltage drop due to discharge reaches nearly 0V, or a current preset limit value. Is exceeded, it is determined that the insulation of the sample insulating material 4 is broken.

  Here, the technical significance of the inverter drive motor insulation evaluation method of the present invention will be described based on the actual measurement data shown in FIG. FIG. 18 shows an example in which an inverter surge voltage is applied between the motor terminal and the ground, and a shared voltage between winding turns is measured. The horizontal axis of the figure (a) shows the time of 1 microsecond / div, and a vertical axis | shaft shows a voltage. The horizontal axis of the figure (b) shows time of 50 microseconds / div, and a vertical axis | shaft shows a voltage.

  In the waveform when the time scale shown in FIG. 5B is large, positive and negative polarity alternating voltages are generated between the winding turns at the rising and falling portions of the surge voltage between the ground. When the dotted line in FIG. 5B is expanded to a detailed waveform in the time scale of FIG. 5A, a delay in the propagation time of the surge voltage is recognized between the lead-out turn 181 and the internal turn 182 of the motor winding. As a result of this propagation time delay, a shared voltage between winding turns is generated. It can be seen that the pulse width of the voltage between winding turns is about 0.8 μs, and the voltage duration is very short.

  FIG. 19 shows a model of a spark discharge delay when a pulse voltage is applied to air. In general, when a high voltage is applied to the air, the air does not necessarily immediately undergo a spark discharge (insulation breakdown), but reaches a spark discharge with a certain time delay. This time delay is called spark discharge delay or spark delay. This spark discharge delay is a statistical time delay until the initial electrons appear by chance between the electrodes, and an electron avalanche is formed while the electrons are accelerated by the electric field. Secondary electron emission from the light source and the formation time delay until a spark discharge is formed by the formation of a streamer. Here, the relationship between the spark discharge delay and the voltage duration is considered. First, considering the case where the voltage application time is sufficiently longer than the spark discharge delay, even if the rise time of the voltage is fast, discharge always occurs with the passage of time. On the other hand, if the voltage duration is shortened and the voltage duration is less than the spark discharge delay, the voltage drops before the spark discharge occurs in the air, so the possibility (probability) that spark discharge does not occur increases. . The same thing occurs in the air in the insulator, and at a voltage with a narrow pulse width, there is a high possibility (probability) that the discharge of the air in the insulator (partial discharge) does not occur and the deterioration of the insulator is suppressed. Is likely to be.

  From these facts, it is considered that the voltage parameter that governs at least the partial discharge deterioration characteristics of the insulating material is not the voltage rise time conventionally considered but the voltage duration, that is, the pulse width in the pulse voltage. In addition, as a result of the examination so far, it has been found that this spark discharge delay is on the order of several μs to ms.

  On the other hand, the pulse width of the shared voltage generated between the motor winding turns in FIG. 18 is 1 μs or less, which is sufficiently shorter than the spark discharge delay. Therefore, it is considered that the possibility (probability) that partial discharge occurs and causes insulation deterioration and breakdown is low between the motor winding turns when driving the inverter, as compared with the conventional wide pulse voltage and sine wave voltage. As a result of the examination so far, it has been clarified that the spark discharge delay becomes shorter as the voltage becomes higher. In the present invention, the partial discharge occurrence frequency is measured by changing the shared voltage between winding turns, and evaluation is made including the voltage dependency of such spark discharge delay.

  Based on the above considerations, in inverter-driven motors, when evaluating the insulating material between winding turns that causes premature failure, consider at least a voltage that considers the pulse width of the shared voltage between the motor winding turns. I know I have to.

  Conventionally, the polarity of the pulse voltage has been discussed with a mixture of unipolar and bipolar data. However, at least when evaluating the insulating material between the motor winding turns, the alternating pulse voltage of both polarities is used. I understand that I have to evaluate it by applying electricity.

  Furthermore, the conventional motor winding test uses a lightning impulse voltage that drops only exponentially when the rise time is fast and falls, or an impulse voltage with a vibration waveform superimposed on the wave tail. I came. However, as shown in FIG. 18, not only the voltage rise time but also the fall time is fast in the inverter pulse voltage, and the winding turn-sharing voltage is generated at both the rise and fall portions. Therefore, when the same voltage as that when driving the inverter is generated between the motor winding turns and the motor product is inspected or diagnosed, only the conventional rise time is not tested with a high-speed power supply. It can be seen that a fast pulse voltage must be used for both fall times.

  As described above, in the inverter drive motor insulation evaluation method and apparatus of the present invention, the most severe insulation of the inverter drive motor is between winding turns of the same winding in which the inverter pulse voltage acts as a surge voltage. In view of this, in addition, the sharing ratio of the surge voltage applied between the winding turns in the process of propagation of the surge voltage with a steep rise is different.

  Therefore, in the present embodiment, the life time tp of the sample insulating material is obtained by using the peak voltage Vm of the divided voltage between the motor winding turns generated between the winding turns, the bipolar alternating pulse voltage having the pulse width tw and the frequency fp as the test voltage. Is measured, and the change in the life time tp with respect to the peak voltage Vm is acquired as the insulation life characteristic of the sample insulation material, so that the performance of the insulation material with respect to the inverter pulse voltage can be evaluated, and a highly reliable insulation evaluation method Can be established.

With reference to FIG. 7 and FIG. 8, an embodiment of an insulation inspection method and apparatus for an inverter drive motor according to the present invention will be described. FIG. 7 shows a product insulation life test apparatus to which the insulation test method of this embodiment is applied. The product insulation life test apparatus includes a test power supply unit 71, a partial discharge measurement unit 72, and a data measurement recording device 73 having a function of controlling the test power supply unit 71 and the partial discharge measurement unit 72. Individual products are used for the sample motor 75 to be inspected. The test power supply unit 71 generates a surge voltage simulating the magnitude ΔV of the surge voltage at the motor terminal when the inverter is driven and the rise time tr. It is desirable that a voltage of 0 to 15 kV or more can be generated as the magnitude ΔV of the surge voltage. Further, the rise time tr is 1 μs or less, and it is desirable that the rise time tr can be varied constantly or at a voltage stop in increments of 0.1 μs or less within a range of 0.1 to 1.0 μs. Alternatively, in a device in which the rise time tr is fixed, the conversion formula shown in the following equation (7) is used so that the divided voltage between the motor winding turns under test is the same as the divided voltage between the winding turns at the time of driving the inverter. Test with the converted surge voltage.
ΔV (test equipment) =
ΔV (Inv) · α (tr (Inv)) / α (tr (test apparatus)) (7)
However, ΔV (test equipment): magnitude of surge voltage of test equipment ΔV (Inv): magnitude of surge voltage at the motor end of the inverter drive motor α (tr (test equipment)):
Voltage sharing ratio between motor windings when a surge voltage of the test apparatus is applied α (tr (Inv)):
Motor winding when the motor-side surge voltage of the inverter drive motor is applied Turn-to-turn voltage sharing ratio tr (test device): surge voltage rise time tr (Inv) of the test device:
Surge voltage rise time at the motor end of the inverter drive motor

  It is desirable to use the same time as the rise time for the fall time of the surge voltage. Further, the range of 1 μs to 10 ms can be adopted as the pulse width pw of the surge voltage in a state where a rotor is incorporated in the product and a rotation test can be performed. However, in the state where the rotor is not incorporated, no counter electromotive force is generated, and an excessive current flows in the motor winding. Therefore, it is desirable to adopt a range of 1 μs to 10 μs for the pulse width pw. An example of the surge voltage waveform is shown in FIG.

  The partial discharge measuring unit 72 measures partial discharge occurrence frequency-motor applied voltage characteristics when a surge voltage is applied to the sample motor 75. The data measurement recording device 73 controls the magnitude ΔV of the surge voltage of the test power supply unit 71, the rise time tr, the pulse width pw, and the repetition frequency fp, and outputs the partial discharge measurement data in synchronization with the test power supply voltage. Data is recorded from 72 via the control line 74. The obtained data is plotted in a graph of partial discharge occurrence frequency Np, Nx-voltage applied voltage characteristics shown in FIG.

  FIG. 8 shows a flowchart of an insulation inspection method carried out by the product insulation inspection apparatus of this embodiment.

(Step S21)
First, the magnitude ΔV of the surge voltage to ground at the motor terminal when the sample motor 75 is driven by an inverter, the rise time tr, and the repetition frequency fp are obtained by simulation or measurement using a motor.

(Step S22)
When the process of step S21 is impossible, it has been obtained through various studies that the ground-to-ground surge voltage substantially coincides with the inter-phase surge voltage when the ground impedance of the inverter power supply and the motor is small in step S22. Therefore, the surge voltage between phases is used instead of the surge voltage between ground.

(Step S23)
Surge voltage magnitude ΔV obtained in step S21 or S22, rise time tr, voltage imitating surge voltage of repetition frequency fp, or actual inverter voltage is applied to sample motor 75 which is an individual product, and 1 surge A partial discharge occurrence frequency Nx per voltage cycle is obtained.

(Step S24)
In parallel with the processing of step 23, a graph of the peak voltage Vm between the motor winding turns and the partial discharge occurrence frequency Np obtained in the insulating material evaluation of FIG. 2, and the peak voltage Vm at the peak voltage Vm and the insulation lifetime Np. Is converted into a surge voltage magnitude ΔV by the following equation (8), which is used as the insulation life characteristic of the standard product.
ΔV = Vm / α (tr) (8)
Where ΔV is the magnitude of the surge voltage α (tr) is the voltage sharing ratio between the motor windings when the surge voltage of the rise time tr is applied Vm is the peak voltage of the sharing voltage between the motor windings

(Step S25)
The insulation life time tx until the insulation of each product is broken down is the frequency Nx of partial discharge when a surge voltage of magnitude ΔV is applied to each product and the surge voltage of magnitude ΔV on the standard product. Using the time tp until breakdown and the partial discharge occurrence frequency Np when applied, the following equation (9) is used.
tx = (Np / Nx) · tp (9)
By using the partial discharge occurrence frequency Nx for different surge voltage magnitudes ΔV and similarly shifting the insulation life characteristics of standard products by (Np / Nx), the insulation life characteristics of individual products can be created.

(Steps S26 to S32)
In the insulation life characteristic obtained in step S25, if the insulation life time tx is equal to or longer than the required life of the product, the process proceeds to step S27 and is shipped.

  On the other hand, if it becomes a defective product, the process proceeds to step S28 to examine whether the magnitude ΔV of the surge voltage at the motor terminal of the inverter drive motor can be reduced or whether the voltage rise time tr can be increased. If the result of this examination is possible, the process proceeds to step S29, the specification is limited, and the product is shipped as acceptable.

  For products that are further rejected in step S28, the process proceeds from step S30 to step S31, where the surge voltage is measured and applied until breakdown, and the insulation life time until the breakdown occurs, and the breakdown Measure the partial discharge signal intensity. Improve life prediction accuracy by comparing the obtained insulation life time with the insulation life characteristics of defective products predicted in the previous inspection, deriving the correction coefficient of measured data and prediction data, and correcting the prediction method Let

  In addition, the temporal change in the partial discharge signal strength until the dielectric breakdown of the defective product is normalized with the insulation life time tx and compared with the change over time in the partial discharge signal strength of the standard product similarly normalized with the insulation life time tp. To do. If there is a difference between them, a correction count is obtained to correct the temporal change data of the partial discharge signal intensity of the standard product, and grasp the variation of the partial discharge signal intensity over time. For the defective product that has undergone dielectric breakdown in step S31, the location of the dielectric breakdown is searched, the cause of the insulating material or the production method is identified, and the result is fed back to the insulating material and product production process.

(Example of test power supply unit 71)
FIG. 9 shows a first example of the test power supply unit 71 of the product insulation life test apparatus. The test power supply unit 71 alternately switches the outputs of the DC power supplies 91 and 92 with the pulse switch 93 to create a square wave pulse voltage having the same rise and fall times and the same rise and fall times. The adjustment unit 94 adjusts the rise / fall time of the surge voltage to a predetermined value and outputs it to one output terminal 95. That is, the circuit of FIG. 9 can output a positive and negative symmetric surge voltage close to that of an actual two-level inverter. The other output terminal 96 for the low-voltage side voltage is connected to the other-phase winding of the sample motor 75 so that the potential of the other-phase winding does not fluctuate and at the same time charge / discharge the electric charge in the motor. To do. However, if the current capacity of the pulse switch 93 is large and the electric charge accumulated in the motor can be charged / discharged through the pulse switch 93, or if the electrostatic capacity of the motor winding is small, a terminal 96 is provided, There is no need to connect. The DC power supplies 91 and 92 and the pulse switch 93 are controlled by a data measuring and recording device 73 connected to a control line 97 indicated by a broken line.

  In FIG. 10, the 2nd example of the test power supply part 71 of a product insulation lifetime inspection apparatus is shown. The test power supply unit 71 turns on and off the outputs of the DC power supplies 101 and 102 with a pulse switch 103 to create a positive / negative symmetrical rectangular wave pulse voltage, and further generates a surge voltage with a rise / fall time adjustment unit 104. The rise / fall time can be adjusted to a predetermined value and output to the output terminal 105 to output a positive / negative symmetric surge voltage close to that of an actual two-level inverter. The pulse switch 103 of this example has only one switch element. However, in this example, the output impedance 108 of the pulse switch 103 is set to a low impedance of 100Ω or less, and when the pulse switch 103 is turned off, a sudden negative voltage change occurs in the rectangular wave, so that both rising and falling are generated. A steep rectangular wave voltage is obtained. The other output terminal 106 for the low-voltage side voltage is connected to the other phase winding of the motor so that the potential of the other phase winding does not fluctuate and at the same time charge / discharge the electric charge in the motor. However, as in the first example, when the current capacity of the pulse switch 103 is large or the electrostatic capacity of the motor winding is small, it is not necessary to provide the terminal 106 or connect it to another phase. The DC power supplies 101 and 102 and the pulse switch 103 are controlled by a data measurement recording device 73 connected to a control line 107 indicated by a broken line.

  In FIG. 11, the 3rd example of the test power supply part 71 of a product insulation lifetime inspection apparatus is shown. The test power supply unit 71 alternately switches the output of the DC power supply 111 with the pulse switch 113 to create a rectangular wave pulse voltage with the same rise time and fall time, and further generates a surge voltage with the rise / fall time adjustment unit 114. The rise / fall time of the voltage is adjusted to a predetermined value and output to the output terminal 115. The other low-voltage side voltage output terminal 116 is connected to the other-phase winding of the motor to prevent the potential of the other-phase winding from fluctuating and at the same time to charge / discharge electric charges in the motor. The DC power supply 111 and the pulse switch 113 are controlled by a data measurement recording device 73 connected to a control line 117 indicated by a broken line. In this example, the circuit configuration is the same as that of the first example in FIG. 9 except that the number of DC power supplies is one. However, in this example, since one end of the DC power supply is grounded, at least one of the pulse switches 113 causes a driver that converts a signal on the control line to a signal suitable for the pulse switch is floated to a high voltage with respect to the ground. There is no need, and the internal insulation structure of the pulse switch is simplified compared to the pulse switch of FIG.

  FIG. 12 shows a fourth example of the test power source 71 of the product insulation life test apparatus. The test power supply unit 71 turns the output of the DC power supply 121 on / off with the pulse switch 123 to create a rectangular pulse voltage, and further rises / falls the surge voltage with the rise / fall time adjustment unit 124. Is adjusted to a predetermined value and output to the output terminal 125. The pulse switch 103 of this example has only one switch element. However, in this example, the output impedance 128 of the pulse switch 123 is set to a low impedance of 100Ω or less, and when the pulse switch 123 is turned off, a sudden negative voltage change occurs in the rectangular wave. A steep rectangular wave voltage is obtained. The other output terminal 126 for the low-voltage side voltage is connected to the other phase winding of the motor so that the electric potential of the other phase winding does not fluctuate and at the same time charge / discharge the electric charge in the motor. The DC power supply 121 and the pulse switch 123 are controlled by a data measurement recording device connected to a control line 127 indicated by a broken line.

(Example of partial discharge measuring circuit 72)
FIG. 13 shows an example of the partial discharge measuring circuit 72 of the product insulation life test apparatus. The partial discharge measuring circuit 72 includes a voltage measuring voltage divider 131, a coupling capacitor 132, a high-frequency current probe 134, a digital oscilloscope 135 for measuring a partial discharge current waveform, and a phase under test of a sample having a three-phase winding. It comprises a UVW changeover switch unit 136 for switching.

  The capacitance of the coupling capacitor 132 is preferably about the same as the capacitance between the sample motor 75 and the ground, and is specifically set between 10 pF and 1000 pF. In the high-frequency current probe 134, the two output lines of the coupling capacitor 132 are passed through in the opposite directions to cancel the charging current associated with the pulse voltage applied to the two phases of the sample, and only the partial discharge current generated inside the sample. Can be measured. The frequency band of the high-frequency current probe 134 is desirably 1 MHz to 1 GHz, and at least 10 MHz to 100 MHz. To the input of the UVW changeover switch unit 136, two high-voltage lines penetrating the current probe in the reverse direction and a low-voltage line supplied from the test power supply 71 are input.

  On the other hand, the output terminal 137 is connected to each input of the U, V, and W three-phase windings of the sample, and the UVW changeover switch unit 136 is controlled by the control signal of the control line 138 (U, VW) during the test. , (V, W-U), and (W, U-V), the test phase is switched so that the two phases of the sample having the three-phase winding are set to high pressure and the remaining one phase is set to low pressure.

  The partial discharge current intensity, occurrence frequency, and applied voltage measured by the current probe 134 and the voltage divider 131 are measured and recorded by the digital oscilloscope 135, and are also recorded by the data measurement recording device 73 connected to the control line 138. . The band of the digital oscilloscope 135 is preferably DC to 1 GHz or more, and the sampling rate is preferably 2 GS / s or more, and at least DC to 100 MHz and the sampling rate needs to be 200 MS / s. The digital oscilloscope 135 can be replaced by an A / D card having the same bandwidth, sampling speed, and memory length. In the digital oscilloscope 135 or the data measurement recording device 73 for controlling the digital oscilloscope 135, a voltage having a predetermined peak value is no longer applied to the sample, or the voltage drop due to discharge reaches near 0V, and the partial discharge current is set in advance. Judgment that the insulation of the sample motor is broken when the limit value is exceeded.

  FIG. 14 shows a circuit configuration example of the UVW automatic changeover switch unit 136. The input terminal 141 is connected to a total of three input lines, two high-voltage lines penetrating the high-frequency current probe in the opposite direction and low-voltage lines. These terminals are supplied to each of the three switches of the switch unit 142. The switching terminals of the three switches of the switch unit 142 are connected to the U, V, and W phases of the sample motor, respectively. The switch unit 142 is connected to any one of two high-voltage lines and three low-voltage lines that pass the U, V, and W phases through the high-frequency current probe in the reverse direction according to the control signal of the control line 148. .

  The apparatus configuration for testing the product motor in a state where the rotor is not incorporated has been shown above. However, an actual inverter power supply can be used as a test power supply in a state where a rotor is incorporated and a rotation test of a product motor can be performed. FIG. 15 shows an example in which an actual inverter power source is incorporated in the test power source and partial discharge measuring unit 76 of the product insulation life test apparatus of FIG. A voltage measuring voltage divider 152 and a partial discharge measuring high-frequency current probe 153 are connected to the output of the inverter power supply 151, and then connected to the U, V, and W output terminals 154. The partial discharge current intensity, occurrence frequency, and applied voltage measured by the current probe 153 and the voltage divider 152 are measured and recorded by the A / D conversion board 156 incorporated in the Compact PCI unit 155. The measurement data is recorded in the data measurement recording device 73 via the control line 158 connected to the I / O signal conversion unit 157. The inverter power supply 151 and the Compact PCI unit are controlled by commands such as “start test”, “data transmission / reception”, and “test end” sent via the control line 158.

  During the test, the inverter power supply 151 cannot output a predetermined voltage, an overcurrent error occurs, a voltage waveform measured by the voltage divider 152 cannot be applied to the sample, or a discharge occurs. When the voltage drop reaches close to 0 V or when the current probe 153 detects a current exceeding a preset limit value, the inverter power supply 151, the Compact PCI unit 155, or the data measurement recording device 73 for controlling them. Determines that the insulation of the sample motor is broken.

  With reference to FIGS. 16 and 17, an embodiment of an inverter drive motor diagnosis method and apparatus according to the present invention will be described. FIG. 16 shows a diagnostic apparatus to which the diagnostic method of this embodiment is applied. The diagnostic apparatus of the present embodiment includes a test power supply unit 161, a partial discharge measurement unit 162, and a data measurement recording device 164 having the control functions of the test power supply unit 161 and the partial discharge measurement unit 162.

  The sample motor 163 to be diagnosed is a product motor whose insulation has deteriorated in the field. The test power source / partial discharge measuring unit 165 composed of the test power source unit 161 and the partial discharge measuring unit 162 can adopt the configuration of FIG. 15 using an inverter power source, and the partial discharge under the actual inverter voltage waveform. The signal can be constantly measured online. Moreover, the test power source / partial discharge measuring unit 165 may be the test power source unit 71 and the partial discharge measuring unit 72 shown in FIGS. In this case, when performing an insulation diagnosis, an off-line periodic diagnosis is performed in which the test apparatus is transported to the field and connected to the sample motor 163 for diagnosis. In any case, the partial discharge measuring unit 162 of the test power source / partial discharge measuring unit 165 measures a change in the partial discharge signal intensity with time. The data measurement / recording device 164 controls the voltage of the test power supply unit 161 and captures and records measurement data of the partial discharge signal intensity from the partial discharge measurement unit 162 via the control line 166 in synchronization with the test power supply voltage. The obtained measurement data is plotted on a graph of partial discharge signal intensity-powering time characteristics.

FIG. 17 shows a diagnosis flow of the diagnosis apparatus of this embodiment.
(Step S41)
In step S41, a threshold number of years x for replacing the product before dielectric breakdown or failure is determined. For example, in the case of a motor for automobiles, since the vehicle inspection period is 2 years, 2 years can be selected for x.

(Steps S42 and S43)
Here, in the time-dependent change data of the partial discharge signal strength of the standard product, the partial discharge signal strength x years before the insulation life tp is obtained, and this is set as the threshold value θth of the partial discharge signal strength for product replacement. The partial discharge of the field product is always or periodically measured by the apparatus shown in FIG. 16, and is compared with the threshold value θth of the partial discharge signal intensity. If the partial discharge signal intensity exceeds the threshold value, the process proceeds to step S43. Then, replace the product with a new one and collect the deteriorated product.

(Step S44)
The recovered deteriorated product continues to apply an inverter surge voltage until the insulation breaks down. At this time, the partial discharge signal strength and the remaining insulation life time are measured, and the variation in signal strength is grasped in the temporal change of the partial discharge signal strength normalized by the insulation life time tx. The threshold value is corrected.

(Step S45)
For deteriorated products that have undergone dielectric breakdown, search for degradation weak points where dielectric breakdown has occurred, and identify the cause of deterioration.

(Step S46)
On the basis of the data obtained in step S45, the motor design and the insulation structure design are changed so that no voltage is applied to the insulation deterioration portion in the next product. Or the insulation of the weak point location which is easy to deteriorate is strengthened. Alternatively, the inspection at the time of product manufacture of weak points where insulation is likely to deteriorate will be strengthened.

DESCRIPTION OF SYMBOLS 1 Test power supply part 2 Partial discharge measurement part 3 Data measurement recording device 4 Sample insulation material 5 Control line

Claims (1)

  When the pulse rise time of the inverter pulse test power supply used when inspecting or diagnosing the motor is different from the rise time of the surge voltage observed at the motor terminal to be inspected and diagnosed when the inverter is driven, A method for inspecting and diagnosing an inverter drive motor, characterized by increasing or decreasing a surge voltage magnitude ΔV of the inverter pulse test power source by a value necessary for applying a peak voltage Vm generated during driving.

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