Rotating machine system and diagnostic method thereof

Abstract

To provide a rotating machine system capable of detecting abnormality of a power transmission mechanism at low cost and in a short time.SOLUTION: In a rotating machine system, a rotating machine 4 and a load machine 8 or a power source or the like are connected via a power transmission mechanism, such as a belt 7. A current measurement part 101 measures a phase current of at least one phase of the rotating machine 4. A frequency spectrum calculation part 102 calculates a frequency spectrum for a phase current measured by the current measurement part 101. A deterioration index calculation part 103 calculates a total value or an average value of amplitude at frequencies excluding a frequency range to be removed including a power supply frequency for a frequency spectrum calculated by the frequency spectrum calculation part 102 as a deterioration index. An abnormality degree calculation part 104 calculates a degree of abnormality on the basis of a deterioration index obtained by the deterioration index calculation part 103.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rotating machine system and a diagnostic method thereof. For example, the present invention relates to a rotating machine system in which a rotating machine and a load machine or a power source are connected via a power transmission mechanism, and a diagnostic method thereof.

Background Art

[0002] Patent Document 1 discloses an abnormality diagnosis device that diagnoses an abnormality in a power transmission mechanism connected to a rotating machine by measuring a current during driving of the rotating machine and performing frequency analysis on the current during driving. Specifically, the abnormality diagnosis device detects a spectral peak by frequency analysis, counts the number of spectral peaks included in an abnormal frequency with sidebands other than the power supply frequency and the rotation frequency of the power transmission mechanism as the abnormal frequency, and diagnoses an abnormality based on an increase in the number.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a system including a rotating machine such as a motor or a generator stops due to a sudden failure, a large damage occurs. In particular, the stop of a rotating machine system used in factory facilities or the like due to a sudden failure has a great impact, such as forcing a reduction in the operating rate of production facilities and a review of the production plan. Therefore, there is an increasing need to prevent sudden failures of rotating machine systems by performing highly accurate pre-failure diagnosis while the system is being used in an actual environment.

[0005] On the one hand, power transmission mechanisms such as belts and chains can simplify the system configuration and reduce costs, so they are used in many rotating machine systems such as air compressors, belt conveyors, automatic doors, blowers, and machine tools. In the case of such inexpensive rotating machine systems, a more inexpensive system for predicting faults is expected for the system that diagnoses the signs of faults.

[0006] Under such circumstances, Patent Document 1 discloses a technique for diagnosing abnormalities in a rotating machine system including a power transmission mechanism by performing frequency analysis of the operating current of a rotating machine without using expensive sensors such as vibration acceleration sensors, and based on the number of spectral peaks at abnormal frequencies. However, in this technique, in order to ensure the high frequency resolution required to identify spectral peaks at abnormal frequencies, it is necessary to accumulate data for a long time, and there is a risk that it may be difficult to diagnose in a short time.

[0007] The present invention has been made in view of such circumstances, and one of its objects is to provide a rotating machine system and a diagnostic method for a rotating machine system that can detect abnormalities in a power transmission mechanism at low cost and in a short time.

[0008] The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Problems

[0009] Among the inventions disclosed in the present application, the outline of a typical embodiment will be briefly described as follows.

[0010] The rotating machine system according to one embodiment is configured such that a rotating machine and a load machine or a power source are connected via a power transmission mechanism, and includes an ammeter, a frequency spectrum calculator, a degradation index calculator, and an abnormality degree calculator. The ammeter measures the phase current of at least one phase of the rotating machine. The frequency spectrum calculator calculates the frequency spectrum of the phase current measured by the ammeter. The degradation index calculator calculates, as a degradation index, the total value or average value of the amplitudes at frequencies excluding the frequency range to be removed including the power supply frequency, from the frequency spectrum calculated by the frequency spectrum calculator. The abnormality degree calculator calculates the abnormality degree based on the degradation index obtained by the degradation index calculator.

Advantages of the Invention

[0011] Among the inventions disclosed in the present application, the effects obtained by typical embodiments will be briefly described as follows: it becomes possible to detect an abnormality in the power transmission mechanism at low cost and in a short time.

Brief Description of the Drawings

[0012]

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Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, the same members are basically denoted by the same reference numerals, and repeated explanations thereof are omitted.

[0014] (Embodiment 1) <Overview of the Rotating Machine System> FIG. 1 is a schematic diagram showing a configuration example of the main part in the rotating machine system according to Embodiment 1. The rotating machine system shown in FIG. 1 includes a rotating machine main body and a diagnostic device 1. The rotating machine main body includes a power supply 3, a rotating machine 4 connected to the power supply 3 to exchange power, and a current sensor 2 for measuring the phase current of the rotating machine 4. The rotating shaft of the rotating machine 4 is connected to a load machine or a power source via a power transmission mechanism including, for example, a first pulley 5, a second pulley 6, and a belt 7. In this example, the first pulley 5 is provided on the rotating shaft of the rotating machine 4, and drives the load machine 8 by rotating the second pulley 6 via the belt 7.

[0015] The diagnostic device 1 reads the signal of the current sensor 2 and executes an abnormality diagnosis. The diagnostic device 1 includes a diagnostic mode activation unit 100, a current measurement unit 101, a frequency spectrum calculation unit 102, a degradation index calculation unit 103, an abnormality degree calculation unit 104, a failure determination unit 105, and an output unit 106. Among these, the diagnostic mode activation unit 100, the current measurement unit 101, the frequency spectrum calculation unit 102, the degradation index calculation unit 103, the abnormality degree calculation unit 104, and the failure determination unit 105 are typically realized by a microcontroller or an FPGA (Field Programmable Gate Array) included in the rotating machine body and responsible for the control operation of the rotating machine 4.

[0016] The current measurement unit 101 is realized by, for example, an analog-to-digital converter in a microcontroller, and measures at least one-phase phase current of the rotating machine 4 via the current sensor 2. In the example described in FIG. 1, the current sensor 2 is installed to measure a one-phase phase current, but it may be installed to measure two or more phases. The diagnostic mode activation unit 100, the frequency spectrum calculation unit 102, the degradation index calculation unit 103, the abnormality degree calculation unit 104, and the failure determination unit 105 are realized by, for example, program processing using a processor in a microcontroller. Details thereof will be described later.

[0017] The output unit 106 outputs various information obtained from the abnormality degree calculation unit 104 or the failure determination unit 105 to the outside of the device, representing the user or the like. The output unit 106 may be, for example, something that appeals to the five senses of humans such as a display, a lamp, a buzzer, or may be something recorded on paper or an electronic file. Alternatively, the output unit 106 may transmit via a communication network such as a wired / wireless LAN (Local Area Network) or Bluetooth (registered trademark).

[0018] Here, when some problem occurs in the power transmission mechanism of the rotating machine system, for example, in the belt 7, and temporary slip occurs, in the frequency spectrum of the phase current of the rotating machine 4, the amplitude at a frequency (referred to as an abnormal frequency in the specification) where no peak occurs in the normal state starts to increase. For example, when quantifying the increase in amplitude at the abnormal frequency in the form of the number of peaks as in the method described in Patent Document 1, it is necessary to achieve a high frequency resolution such that the peaks can be identified. Since the frequency resolution is inversely proportional to the data accumulation time, in the method described in Patent Document 1, there was a risk that diagnosis in a short time would be difficult.

[0019] Therefore, in order to enable diagnosis even when the frequency resolution is low and peaks at abnormal frequencies cannot be identified, the diagnostic device 1 described in FIG. 1 is provided. The diagnostic device 1 generally captures an increase in the average amplitude level of the spectrum as an abnormal sign instead of counting the number of peaks at abnormal frequencies in the frequency spectrum of the phase current. However, if the peak at the power frequency, which is the maximum peak in the frequency spectrum of the phase current, is included in the calculation of the average amplitude level, the sensitivity of abnormal detection decreases. For this reason, when calculating the average amplitude level, the frequency range to be removed including the power frequency is excluded.

[0020] Note that in the frequency spectrum of the phase current, peaks at sidebands corresponding to the rotational frequencies of the load machine 8 and the belt 7 appear even in the normal state. In order to enhance the sensitivity of abnormal detection, it is preferable to exclude those peaks from the calculation of the average amplitude level. However, generally, since those peaks are sufficiently smaller than the peak at the power frequency, there is no problem in practice even if they are not excluded.

[0021] <Details of the Diagnostic Device> FIG. 2 is a flowchart showing an example of a method for diagnosing a rotating machine system by a diagnostic device in FIG. 1. First, in step S100, the diagnostic mode activation unit 100 activates the diagnostic mode. As a specific example of the method for activating the diagnostic mode, in addition to the method in which the user selects from the setting items of the rotating machine system, there are methods such as pressing a mechanical button for activating the diagnostic mode or touching the "diagnostic mode" button displayed on the display.

[0022] As another method, there is a method in which the diagnostic mode activation unit 100 automatically activates the diagnostic mode. That is, the diagnostic mode activation unit 100 activates the diagnostic mode when a preset activation timing is reached or when preset activation conditions are satisfied. As a specific example regarding the activation timing, there is a method in which the user sets a specific date and time in advance for the diagnostic mode activation unit 100.

[0023] As a specific example regarding the activation conditions, the diagnostic mode activation unit 100 may monitor the effective value of the phase current from the current measurement unit 101 and activate the diagnostic mode when the effective value continuously falls within a set range for a set time. In this case, the user sets in advance the range of the effective value of the phase current and its continuous time in the diagnostic mode activation unit 100 as the activation conditions. Also, as another specific example regarding the activation conditions, the diagnostic mode activation unit 100 may activate the diagnostic mode before or after the rotating machine 4 performs a set control operation. In this case, the user sets a specific control operation in advance in the diagnostic mode activation unit 100 as the activation conditions.

[0024] Here, it is desirable that the diagnostic mode be activated during a period when the operating state of the rotating machine 4 is equivalent. This is because when the operating state of the rotating machine 4 changes, the diagnostic conditions, specifically, the optimal threshold values when determining the abnormality level described later, may also change. Therefore, as described above, the diagnostic mode activation unit 100 may activate the diagnostic mode when a preset activation timing is reached or when preset activation conditions are satisfied. In this case, it becomes possible to keep the operating state of the rotating machine 4 almost equivalent when activating the diagnostic mode.

[0025] Next, in step S101, the current measurement unit 101 measures the phase current of at least one phase of the rotating machine 4 via the current sensor 2. Alternatively, the current measurement unit 101 may measure two or more phase currents. Subsequently, in step S102, the frequency spectrum calculation unit 102 calculates the frequency spectrum for the phase current measured by the current measurement unit 101 using FFT (Fast Fourier Transform) or the like.

[0026] FIG. 3 is a schematic diagram showing an example of the frequency spectrum calculated by the frequency spectrum calculation unit of FIG. 1. In FIG. 3, the frequency spectra in the normal state and the abnormal state are superimposed and displayed. In FIG. 3, the peak of the amplitude occurring at 50 Hz is the peak at the power supply frequency of the power supply 3 supplied to the rotating machine 4, in other words, the driving frequency of the rotating machine 4. For example, when some defect occurs in the belt 7 and an abnormal state where a temporary slip occurs, the rotational frequency of the belt 7 fluctuates. As a result, the amplitude at a frequency where no peak occurs in the normal state, that is, an abnormal frequency, such as near 30 Hz, begins to increase.

[0027] Here, if the data accumulation time in the abnormal state is lengthened, for example, a clearer peak appears in the vicinity of 30 Hz in FIG. 3. However, when diagnosis is performed based on the peak, a long diagnosis time is required according to the data accumulation time. Therefore, in order to shorten the diagnosis time, in the method of Embodiment 1, in step S103 of FIG. 2, the deterioration index calculation unit 103 calculates the total value or average value of the amplitudes at frequencies excluding the frequency range to be removed including the power supply frequency as the deterioration index.

[0028] FIGS. 4A and 4B are diagrams for explaining an example of the processing content of the deterioration index calculation unit of FIG. 1. FIG. 4A is the frequency spectrum of the phase current in the normal state, and FIG. 4B is the frequency spectrum of the phase current in the abnormal state. In FIGS. 4A and 4B, excluding the frequency range FE to be removed, which is the power supply frequency and the frequencies in its vicinity, the total value or average value of the amplitudes at the hatched frequencies corresponds to the deterioration index.

[0029] Note that the vertical axis of the frequency spectra shown in FIGS. 4A and 4B is, in detail, on a logarithmic scale. In accordance with this, the deterioration index calculation unit 103 may calculate the total value or average value of the amplitudes using logarithms. For example, when not using logarithms, the difference between the value obtained in the normal state and the value obtained in the abnormal state can become very large, making it difficult to define the boundary between the normal state and the abnormal state in some cases. In such cases, using logarithms is beneficial.

[0030] The method for determining the frequency range FE to be removed may be, for example, a method of determining it as a frequency range having a bandwidth obtained by multiplying the height of the peak at the power supply frequency by a predetermined ratio, or a method of determining it as a frequency range that is a peak adjacent to the peak at the power supply frequency and does not include peaks that occur even in the normal state. The peak adjacent to the peak at the power supply frequency is, in many cases, a peak separated from the power supply frequency by the rotational frequency of the belt 7, or a peak separated from the power supply frequency by the rotational frequency of the load machine 8, specifically, the rotational frequency of the second pulley 6.

[0031] Therefore, the deterioration index calculation unit 103 may, for example, determine the frequency range whose absolute value of the difference from the power supply frequency is smaller than the rotational frequency of the power transmission mechanism as the frequency range FE to be removed, and calculate the deterioration index. Alternatively, the deterioration index calculation unit 103 may determine the frequency range whose absolute value of the difference from the power supply frequency is smaller than the rotational frequency of the load machine 8 or the power source as the frequency range FE to be removed, and calculate the deterioration index.

[0032] Note that in FIGS. 4A and 4B, the deterioration index calculation unit 103 calculated the deterioration index excluding the peak near 50 Hz which is the power supply frequency. However, in addition to this, the deterioration index calculation unit 103 can also exclude peaks that occur near 38 Hz or 62 Hz depending on the frequency resolution, that is, peaks generated based on the rotational frequencies of the power transmission mechanism, load equipment, etc.

[0033] FIG. 5 is a schematic diagram showing an example of the deterioration index calculated by the deterioration index calculation unit of FIG. 1. FIG. 5 shows the time-series changes of the deterioration index calculated in the normal state and the deterioration index calculated in the abnormal state. From FIG. 5, it can be seen that the deterioration index is clearly larger in the abnormal state compared to the normal state.

[0034] Next, in step S104 of FIG. 2, the abnormality degree calculation unit 104 calculates the abnormality degree based on the deterioration index obtained by the deterioration index calculation unit 103. For example, the abnormality degree calculation unit 104 uses the obtained deterioration index as the abnormality degree as it is. Alternatively, the abnormality degree calculation unit 104 calculates the moving average of the deterioration index and uses it as the abnormality degree.

[0035] Subsequently, in step S105, the failure determination unit 105 determines whether the abnormality degree calculated by the abnormality degree calculation unit 104 exceeds a preset threshold value. If it exceeds, it is determined that there is a sign of failure. Then, in step S106, when the failure determination unit 105 determines that there is a sign of failure, a warning is issued from the output unit 106. Note that even when the failure determination unit 105 determines that there is no sign of failure, it may output the diagnosis result to that effect from the output unit 106.

[0036] Here, the threshold value for determining the presence or absence of a sign of failure may be determined based on the results separately examined with a testing machine or the like, or may be determined by learning in an actual environment using the actual machine. As a specific example, first, the abnormality degree is calculated multiple times during a preset learning period in the actual environment. At this time, the abnormality degree calculated each time among the multiple times may vary slightly even in the normal state. Therefore, for example, the average value and the fluctuation range of the abnormality degree calculated multiple times are obtained, and a threshold value at a level that does not cause false alarms is determined by adding a predetermined margin thereto.

[0037] Further, separately, so that precise diagnosis can be performed by machine learning or the like, the abnormality degree calculation unit 104 may output the calculated abnormality degree from the output unit 106 together with parameters that define the operating state of the rotating machine 4. Examples of such parameters include the target value of the rotational speed with respect to the rotating machine 4, the phase current, and thus the target value of the torque. By recording such multivariate data with a logger or the like and analyzing it with a machine learning algorithm such as vector quantization clustering, it can be expected that weak abnormalities that could not be detected by threshold determination can be detected.

[0038] Furthermore, an appropriate threshold value for the abnormality degree may be obtained for each operating state of the rotating machine 4. As a result, not only when the operating state of the rotating machine 4 is the same as described in step S100, but also when the operating state of the rotating machine 4 changes, it becomes possible to respond. That is, even if the diagnostic mode is activated at an arbitrary timing, and furthermore, even if the operating state of the rotating machine 4 during the diagnostic mode changes, it becomes possible to determine the presence or absence of a sign of failure while appropriately changing the threshold value according to the operating state of the rotating machine 4.

[0039] <Main effects of Embodiment 1> As described above, by using the rotating machine system and its diagnostic method according to Embodiment 1, unlike the method of Patent Document 1, even if the frequency resolution is low, that is, even if the data accumulation time is short, an abnormality in the power transmission mechanism can be detected. In addition, an abnormality in the power transmission mechanism can be detected without using an expensive sensor such as a vibration acceleration sensor. As a result, typically, it becomes possible to detect an abnormality in the power transmission mechanism at low cost and in a short time.

[0040] (Embodiment 2) <Details of the diagnostic device> FIG. 6 is a flowchart showing an example of a method for diagnosing a rotating machine system by the diagnostic apparatus of FIG. 1 in the rotating machine system according to Embodiment 2. The difference from FIG. 2 is that the following step S203 is provided instead of step S103 in FIG. 2. In step S203, the deterioration index calculation unit 103 calculates the total value or average value of the amplitudes at frequencies excluding a plurality of frequency ranges FE to be removed corresponding to n times (n = 0, 1, 2, 3,...) of the power supply frequency as a deterioration index.

[0041] For example, when the current measurement unit 101 measures the phase current at a sampling frequency of 1 kHz, the frequency spectrum calculation unit 102 can calculate the frequency spectrum in the range up to about 500 Hz. In this case, for example, in the range of 0 Hz to 500 Hz, the frequency ranges in the vicinity of each frequency centered on the frequency every 50 Hz are respectively defined as the frequency ranges FE to be removed described in FIGS. 4A and 4B.

[0042] The peaks of n times (n = 0, 1, 2, 3,...) of the power supply frequency appear even in the normal state. If the total value or average value of the amplitudes is calculated including such peaks, the ratio of the value of the deterioration index obtained in the normal state to the value of the deterioration index obtained in the abnormal state increases, and there is a risk that the abnormal detection sensitivity decreases. Therefore, by calculating the deterioration index excluding the peaks of n times the power supply frequency and their vicinities, it becomes possible to further increase the abnormal detection sensitivity.

[0043] (Embodiment 3) <Outline of the rotating machine system> FIG. 7 is a schematic diagram showing a configuration example of a main part in a rotating machine system according to Embodiment 3. The difference from FIG. 1 is that each part in the diagnostic device 1 in FIG. 1 is divided into two diagnostic devices 1a and 1b. As an example, in FIG. 7, the diagnostic device 1a is installed inside or near the rotating machine body, and has a transmission unit 110 in addition to a diagnostic mode activation unit 100 and a current measurement unit 101. On the other hand, the diagnostic device 1b is a cloud device or the like installed remotely from the rotating machine body, and has a reception unit 111 in addition to a frequency spectrum calculation unit 102, a deterioration index calculation unit 103, an abnormality degree calculation unit 104, a failure determination unit 105, and an output unit 106.

[0044] The transmission unit 110 in the diagnostic device 1a is realized by, for example, a communication network interface mounted on the rotating machine body. On the other hand, in the diagnostic device 1b, the frequency spectrum calculation unit 102, the deterioration index calculation unit 103, the abnormality degree calculation unit 104, and the failure determination unit 105 are realized by, for example, program processing by a processor mounted on a cloud device or the like. The reception unit 111 is realized by, for example, a communication network interface mounted on a cloud device or the like.

[0045] The transmission unit 110 in the diagnostic device 1a transmits the current data of the phase current measured by the current measurement unit 101 to the diagnostic device 1b via the communication network 15. The communication network 15 is based on standards such as Ethernet (registered trademark), wired / wireless LAN (Local Area Network), and Bluetooth (registered trademark). On the other hand, the reception unit 111 in the diagnostic device 1b receives the current data via the communication network 15. Then, the frequency spectrum calculation unit 102 in the diagnostic device 1b executes processing in response to the current data from the reception unit 111. Note that the diagnostic mode activation unit 100 may be mounted on the diagnostic device 1b. In this case, the diagnostic device 1b may issue an instruction to activate the diagnostic mode to the diagnostic device 1a via the communication network 15.

[0046] <Main effects of Embodiment 3> As described above, in the third embodiment, by using a configuration in which each part of the diagnostic device is divided and a part is installed remotely, the processing load of the diagnostic device 1a installed inside or near the rotating machine main body can be reduced. As a result, in addition to the various effects described in the first embodiment, the rotating machine main body can be made less expensive. Further, since a method that can reduce the amount of current data accumulation is used, different from the method of Patent Document 1, the communication load from the diagnostic device 1a to the diagnostic device 1b can also be reduced.

[0047] (Embodiment 4) <Schematic of the rotating machine system> FIG. 8 is a schematic diagram showing a configuration example of main parts in a rotating machine system according to the fourth embodiment. The configuration of FIG. 8 is different from the configuration of FIG. 7 in the division form of each part in the diagnostic device 1. The diagnostic device 1c is installed inside or near the rotating machine main body, and has a transmission unit 110 in addition to a diagnostic mode activation unit 100, a current measurement unit 101, and a frequency spectrum calculation unit 102. On the other hand, the diagnostic device 1d is a remotely installed cloud device or the like, and has a reception unit 111 in addition to a deterioration index calculation unit 103, an abnormality degree calculation unit 104, a failure determination unit 105, and an output unit 106.

[0048] The transmission unit 110 in the diagnostic device 1c transmits the frequency spectrum data calculated by the frequency spectrum calculation unit 102 to the diagnostic device 1d via the communication network 15. On the other hand, the reception unit 111 in the diagnostic device 1d receives the frequency spectrum data via the communication network 15. Then, the deterioration index calculation unit 103 in the diagnostic device 1d executes processing in response to the frequency spectrum data from the reception unit 111. Note that the installation location of the diagnostic mode activation unit 100 is the same as that in the third embodiment.

[0049] <Main effects of the fourth embodiment> As described above, by using the configuration of the fourth embodiment, the same effects as the various effects described in the third embodiment can be obtained. In particular, when the frequency range of the frequency spectrum required for data communication is limited to the range used in subsequent processing, the communication volume can be further reduced, and the communication cost during operation can be saved.

[0050] (Embodiment 5) (Outline of the rotating machine system) FIG. 9 is a schematic diagram showing a configuration example of main components in a rotating machine system according to Embodiment 5. The configuration in FIG. 9 is different from the configurations in FIGS. 7 and 8 in the division form of each part in the diagnostic device 1. The diagnostic device 1e is installed inside or near the rotating machine main body, and has a transmission unit 110 in addition to a diagnostic mode activation unit 100, a current measurement unit 101, a frequency spectrum calculation unit 102, and a deterioration index calculation unit 103. On the other hand, the diagnostic device 1f is a remotely installed cloud device or the like, and has a reception unit 111 in addition to an abnormality degree calculation unit 104, a failure determination unit 105, and an output unit 106.

[0051] The transmission unit 110 in the diagnostic device 1e transmits the data of the deterioration index calculated by the deterioration index calculation unit 103 to the diagnostic device 1f via the communication network 15. On the other hand, the reception unit 111 in the diagnostic device 1f receives the data of the deterioration index via the communication network 15. Then, the abnormality degree calculation unit 104 in the diagnostic device 1f executes processing upon receiving the data of the deterioration index from the reception unit 111. Note that the installation location of the diagnostic mode activation unit 100 is the same as that in Embodiment 3.

[0052] (Main effects of Embodiment 5) As described above, by using the configuration of Embodiment 5, the same effects as those described in Embodiment 3 can be obtained. Furthermore, since the data amount of the deterioration index is small, the communication volume can be greatly reduced, and the communication cost during operation can be significantly saved.

[0053] (Embodiment 6) (Application example of the rotating machine system) FIG. 10 is a schematic diagram showing a configuration example of a compressor as an application example of the rotary machine system according to Embodiment 6. In FIG. 10, the load machine 8 is a compressor main body here, and it is connected to a tank 9. In an air compressor, there is usually a time period when the rotary machine 4 operates at a constant speed and a constant load, such as immediately after startup. Therefore, it is desirable for the diagnostic device 1 to execute diagnosis at that timing. Such a time period exists, for example, in an unloaded state where air is not being compressed.

[0054] Also, when diagnosing during actual operation of the air compressor, as described in Embodiment 1, the diagnostic mode activation unit 100 may activate the diagnostic mode when the effective value of the phase current enters a set range. Or, the diagnostic mode activation unit 100 may activate the diagnostic mode before or after the rotary machine 4 performs a specific control operation. However, in this case, depending on the load state, that is, the progress of compression, etc., the magnitude of each peak in the frequency spectrum may vary up and down as a whole. In such a case, the deterioration index calculation unit 103 may calculate the deterioration index after normalizing the frequency spectrum with the peak value at the power frequency.

[0055] (Embodiment 7) <Application Example of Rotary Machine System> FIG. 11 is a schematic diagram showing a configuration example of a belt conveyor as an application example of the rotary machine system according to Embodiment 7. In the belt conveyor, there is usually a time period when there is no conveyed item 10 on the belt 7 and the rotary machine 4 operates at a constant speed and a constant load. Therefore, it is desirable for the diagnostic device 1 to execute diagnosis at that timing.

[0056] (Embodiment 8) <Application Example of Rotary Machine System> FIG. 12 is a schematic diagram showing a configuration example of an automatic door, which is an application example of the rotary machine system according to the eighth embodiment. In FIG. 12, doors 11a and 11b are respectively installed at two positions on a belt 7 that moves in the reverse direction when the rotary machine 4 is driven. Further, the doors 11a and 11b are in sliding contact with a rail 12 and slide in the reverse direction on the rail 12 in accordance with the movement of the belt 7. In the case of an automatic door, although there is not much time when the rotary machine 4 has a constant speed, the opening and closing pattern of the door is almost determined. Therefore, it is desirable that the diagnostic device 1 selects the timing under the same conditions based on the opening and closing pattern of the door and executes the diagnosis.

[0057] As described above, the embodiments have been described. However, the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0058] Furthermore, the rotary machine system of the embodiment is not limited to the air compressor, belt conveyor, and automatic door described in FIGS. 10, 11, and 12, but can be widely applied to rotary machine systems having a power transmission mechanism such as a belt or a chain, such as a blower and a machine tool. Furthermore, it can also be applied to robots, power steering, engine generators, OA equipment, and the like.

Description of Reference Numerals

[0059] 1, 1a, 1b, 1c, 1d, 1e, 1f Diagnostic device 2 Current sensor 3 Power supply 4 Rotary machine 5, 6 Pulleys 7 Belt 8 Load machine 9 Tank 10 Transport item 11a, 11b Doors 12 Rail 15 Communication network 100 Diagnosis mode activation unit 101 Ammeter 102 Frequency spectrum calculation unit 103 Degradation index calculation unit 104 Abnormality degree calculation unit 105 Fault determination unit 106 Output unit 110 Transmitter 111 Receiver Frequency range for FE removal

Claims

1. A rotating machine system in which a rotating machine and a load machine or a power source are connected via an annular power transmission mechanism, a current measurement unit that measures at least one-phase phase current of the rotating machine, a frequency spectrum calculation unit that calculates a frequency spectrum for the phase current measured by the current measurement unit, a deterioration index calculation unit that calculates a total value or an average value of amplitudes at frequencies excluding a frequency range to be removed including a power supply frequency with respect to the frequency spectrum calculated by the frequency spectrum calculation unit, and uses the result as a deterioration index, an abnormality degree calculation unit that calculates an abnormality degree based on the deterioration index obtained by the deterioration index calculation unit, comprising: The deterioration index calculation unit determines the frequency range to be removed as a frequency range in which an absolute value of a difference from the power supply frequency is smaller than a rotation frequency at which the power transmission mechanism makes one revolution, and calculates the deterioration index. A rotating machine system.

2. In the rotating machine system according to Claim 1, the deterioration index calculation unit determines the frequency range to be removed as a frequency range in which an absolute value of a difference from the power supply frequency is smaller than a rotation frequency of the load machine or the power source, and calculates the deterioration index. A rotating machine system.

3. In the rotating machine system according to Claim 1 or 2, the deterioration index calculation unit calculates a total value or an average value of the amplitudes at frequencies excluding a plurality of frequency ranges to be removed respectively corresponding to n times (n = 0, 1, 2, 3,...) of the power supply frequency, and uses the result as the deterioration index. A rotating machine system.

4. In the rotating machine system according to any one of Claims 1 to 3, the deterioration index calculation unit calculates the total value or the average value of the amplitudes using logarithms. A rotating machine system.

5. In the rotating machine system according to any one of Claims 1 to 4, further comprising a failure determination unit that determines whether or not the abnormality degree calculated by the abnormality degree calculation unit exceeds a preset threshold value, and issues a warning when the abnormality degree exceeds the threshold value. A rotating machine system.

6. In the rotating machine system according to Claim 5, the threshold value is determined using the abnormality degree calculated during a preset learning period. A rotating machine system.

7. In the rotating machine system according to any one of Claims 1 to 6, Furthermore, there is a diagnostic mode activation unit that activates a diagnostic mode for calculating the degree of abnormality from the phase current measured by the current measurement unit when a preset activation timing is reached or when preset activation conditions are satisfied. Rotating machine system.

8. In the rotating machine system according to claim 7, the diagnostic mode activation unit monitors the phase current measured by the current measurement unit, and activates the diagnostic mode when the effective value of the phase current continuously falls within a set range for a set time. Rotating machine system.

9. In the rotating machine system according to any one of claims 1 to 8, the abnormality degree calculation unit outputs the calculated degree of abnormality together with parameters that define the operating state of the rotating machine. Rotating machine system.

10. In the rotating machine system according to any one of claims 1 to 9, furthermore, between the current measurement unit and the frequency spectrum calculation unit, or between the frequency spectrum calculation unit and the deterioration index calculation unit, or between the deterioration index calculation unit and the abnormality degree calculation unit, there is a transmission unit that transmits data via a communication network, and a reception unit that receives the data via the communication network. Rotating machine system.

11. A method for diagnosing a rotating machine system in which a rotating machine is connected to a load machine or a power source via an annular power transmission mechanism, measuring at least one phase current of the rotating machine, calculating a frequency spectrum for the measured phase current, calculating a total value or an average value of amplitudes at frequencies excluding a frequency range to be removed including the power supply frequency from the calculated frequency spectrum as a deterioration index, and calculating a degree of abnormality based on the obtained deterioration index. When calculating the deterioration index, a frequency range in which the absolute value of the difference from the power supply frequency is smaller than the rotation frequency at which the power transmission mechanism makes one revolution is defined as the frequency range to be removed. Diagnostic method for a rotating machine system.

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