Transmission Monitoring System

Abstract

To provide a speed change gear monitoring system capable of identifying vibration frequency for diagnosing a speed change gear from current information relevant to a motor, which is complex-superposed of mechanical and electrical noises.SOLUTION: The speed change gear monitoring system includes: a diagnostic frequency estimation unit 8 that extracts multiple diagnostic frequency candidate groups from a frequency region separated by a specific frequency Δf or more by using at least current information relevant to a motor 4, transmission gear ratio of a speed change gear 5, and the number of steps of the speed change gear 5, and estimates frequencies that satisfy a specific relationship as diagnostic frequencies out of the frequencies obtained in multiple diagnostic frequency candidate groups; and an abnormal diagnosis unit 15 that diagnoses an abnormal of the speed change gear 5 by using at least one diagnostic frequency estimated by the diagnostic frequency estimation unit 8.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a transmission monitoring system for monitoring a transmission driven by a motor. [Background technology]

[0002] In recent years, the spread of the Internet of Things (IoT) and the sophistication of artificial intelligence (AI) have come together with a declining working population, and attention has been focused on technology that automatically diagnoses abnormalities in machinery and equipment based on information obtained by sensors, etc. Among these, for equipment driven by a motor, many diagnostic technologies have been disclosed that use vibration sensors, taking advantage of the fact that vibrations occur when an abnormality occurs. A representative example is a method of diagnosing abnormalities in rotating parts such as bearings and gears by monitoring the increase in the vibration frequency components (amplitude) specific to the parts. With this method, it is possible to estimate the abnormal state based on the increase or decrease in frequency components, and at the same time, it is possible to identify the abnormal part corresponding to each frequency.

[0003] At this time, it is very important to identify the vibration frequency, and especially in a system equipped with a transmission, it is necessary to identify all the vibration frequencies of each shaft / each rotating part before and after the gear shift. However, the machine specifications (design specifications) for identifying these frequencies are often not disclosed. Even if information on the machine specifications is available, it may be difficult to detect a specific frequency in an environment where vibrations from machines other than the machine to be diagnosed are generated everywhere. This can result in problems such as time being required to identify the frequency or selecting the wrong frequency.

[0004] Therefore, Patent Document 1 discloses a method for identifying the vibration frequency of each rotating shaft / each part before and after a gear shift, even in a complex device that includes a transmission, without specification information. Specifically, the method uses a predicted value of the meshing frequency of the gears included in the transmission and the maximum peak value (amplitude) within the range of the predicted value of the frequency to identify, for example, the meshing frequency and the number of teeth of the gears (if the number of teeth is known, the reduction ratio and the rotation speed of each shaft can also be calculated). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-181282 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, although the technology described in Patent Document 1 is applicable when a vibration sensor is used, it is not suitable for a diagnostic method using a current sensor that can diagnose rotating parts in the same way as a vibration sensor.

[0007] The reason is that electrical noise (vibration) is superimposed on the motor current as well as mechanical vibration components. It is a well-known fact that mechanical vibration components that occur when an abnormality occurs are also superimposed on the motor current. Electrical noise is, for example, harmonics that are generated when driving a motor (AC motor). In addition, since the electrical noise may be larger than the peak value (amplitude) of the mechanical vibration, it is difficult to identify the mechanical vibration frequency (diagnosis frequency) for abnormality diagnosis using a method using maximum peak search as in Patent Document 1.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to identify a vibration frequency for diagnosing an abnormality in a rotating part of a transmission from current information related to a motor in which mechanical vibrations and electrical vibrations are combined and superimposed. [Means for solving the problem]

[0009] In order to solve the above problems, a transmission monitoring system of one embodiment of the present invention is a transmission monitoring system that monitors a transmission driven by a motor, and includes a diagnostic frequency estimation unit that uses at least current information related to the motor, a gear ratio of the transmission, and the number of gears in the transmission to extract a group of diagnostic frequency candidates from a frequency range that is separated by a specific frequency or more, and estimates a frequency that satisfies a specific relationship from among the frequencies obtained in the group of diagnostic frequency candidates as a diagnostic frequency, and an abnormality diagnosis unit that diagnoses an abnormality in the transmission using at least one of the diagnostic frequencies estimated by the diagnostic frequency estimation unit. Effect of the Invention

[0010] According to at least one aspect of the present invention, it is possible to accurately and automatically estimate vibration frequency components for diagnosing abnormalities in rotating parts of a transmission from current information related to a motor in which mechanical and electrical vibrations are combined. By using the diagnostic frequency components, it is expected that the diagnostic accuracy will be improved and the time required to build the transmission monitoring system will be shortened. Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0011] [Figure 1] 1 is a block diagram showing an example of the configuration of a transmission monitoring system according to a first embodiment of the present invention. [Diagram 2] 2 is a block diagram showing an example of the configuration of a signal conversion unit according to the first embodiment of the present invention. FIG. [Diagram 3] 4 is a block diagram showing another example of the configuration of the signal conversion unit according to the first embodiment of the present invention. FIG. [Figure 4] FIG. 1 is a diagram showing an example of a waveform obtained by frequency analysis of a phase current of a mechanical device (motor). [Diagram 5] 5 is a flowchart showing an example of a processing procedure by a computation management unit according to the first embodiment of the present invention. [Figure 6] FIG. 2 is a diagram illustrating a configuration example of a transmission. [Figure 7] 2 is a block diagram showing an example of the configuration of a diagnostic frequency candidate extraction unit according to the first embodiment of the present invention. FIG. [Figure 8] FIG. 11 is a block diagram showing an example of the configuration of a transmission monitoring system according to a second embodiment of the present invention. [Figure 9] FIG. 11 is a block diagram showing an example of the configuration of a signal conversion unit according to a second embodiment of the present invention. [Figure 10] FIG. 11 is a block diagram showing an example of the configuration of a transmission monitoring system according to a third embodiment of the present invention. [Figure 11] FIG. 11 is a block diagram showing an example of the configuration of a signal conversion unit according to a third embodiment of the present invention. [Figure 12] FIG. 11 is a block diagram showing an example of the configuration of a diagnostic frequency candidate extraction unit according to a third embodiment of the present invention. [Figure 13] FIG. 11 is a block diagram showing an example of the configuration of a transmission monitoring system according to a fourth embodiment of the present invention. [Figure 14] FIG. 13 is a diagram illustrating an example of a frequency spectrum of a torque current estimate, including a first diagnostic frequency candidate group and a second diagnostic frequency candidate group. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, examples of embodiments of the present invention will be described with reference to the accompanying drawings. In this specification and the accompanying drawings, components having substantially the same functions or configurations are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0013] <First embodiment> First, a transmission monitoring system according to a first embodiment of the present invention will be described. In the first embodiment of the present invention, a transmission monitoring system is described which diagnoses abnormalities in a mechanical device (particularly a transmission) by estimating the vibration frequency (diagnosis frequency) required for diagnosing rotating parts based on information on a two-phase motor current, the total gear ratio of the mechanical device, the number of gears, and the number of motor poles.

[0014] [Configuration of the transmission monitoring system] FIG. 1 is a block diagram showing an example of the configuration of a transmission monitoring system according to a first embodiment of the present invention. In Fig. 1, a transmission monitoring system 100 for monitoring the state of a machine 7 includes a diagnostic frequency estimation unit 8 and an abnormality diagnosis unit 15. The diagnostic frequency estimation unit 8 estimates a diagnostic frequency using as input the total gear ratio inside the machine 7, current information (motor current (phase current) in Fig. 1) related to the motor 4 (three-phase AC motor), the number of gears, and the number of motor poles. The abnormality diagnosis unit 15 calculates the degree of abnormality of the machine 7 using as input the diagnostic frequency calculated by the diagnostic frequency estimation unit 8, and monitors the state of the machine 7. The number of gears is a value indicating how many times the gears should be changed in order to achieve the total gear ratio. In the example of a transmission 5 shown in Fig. 6 described later, the number of gears is three.

[0015] Here, in this specification, the diagnostic frequency refers to the speed (frequency) of each rotating shaft before and after shifting in the transmission 5. In the transmission 5 shown in Fig. 6, it corresponds to the speed (frequency) of the four rotating shafts 51 to 54. Each of the above devices and processing units will be described in detail below.

[0016] [Mechanical equipment] First, the mechanical device 7 will be described. The machine 7 is a schematic representation of an object diagnosed by the transmission monitoring system 100. Examples of the machine 7 include industrial equipment such as machine tools, fans / pumps, and hoists, automobiles, construction machinery, railroad cars, and home appliances. The machine 7 is composed of a motor 4 driven by AC voltage from a drive power source 1, which means a commercial power source or an inverter, a transmission 5 connected to the motor 4, and a load device 6 to which power is transmitted from the transmission 5. Here, the transmission 5 is a device such as a reducer or speed increaser that changes the rotational speed of a rotating shaft (rotating part) by gears, and is the sum of all the transmission mechanisms (gear ratios) included in the machine 7.

[0017] [Diagnosis frequency estimation part] Next, the diagnostic frequency estimation unit 8 will be described. The diagnostic frequency estimation unit 8 is a processing block that extracts the frequencies (diagnostic frequencies) of multiple rotating shafts before and after a gear shift based on input information such as the motor current value. Note that the diagnostic frequency estimation unit 8 estimates the frequencies (diagnostic frequencies) of the rotating shafts after gear shifting one gear (one step) at a time starting from the input shaft, except for the frequencies of the input shaft (rotating shaft 51) and output shaft (rotating shaft 54) of the transmission 5 shown in Fig. 6.

[0018] First, the signal conversion unit 9 receives as input the two-phase motor currents (phase currents) detected by the current sensors 2 and 3, which are current detection means, as information relating to the current of the motor 4, and the number of motor poles, and outputs an estimated torque current value and an estimated motor speed value. For example, the diagnostic frequency estimation unit 8 can be realized by a microcomputer or an FPGA (Field Programmable Gate Array), and in practice the motor current is read via an AD converter (the AD converter is omitted in FIG. 1).

[0019] The torque current is a current that flows according to the torque generated by the motor 4, and has little frequency change and can be treated as a direct current. The current acquired at this time is a two-phase current, but may be a three-phase current. In addition, in the case of a two-phase current, the two phases acquired may be any combination of the U phase, V phase, and W phase. In this embodiment, the current is acquired from the U phase and the V phase.

[0020] The motor pole number represents the number of poles of the magnet used in the rotating rotor of the motor 4. The motor pole number may be determined, for example, by a user manually inputting information written on the nameplate of the motor 4 to the transmission monitoring system 100. The torque current estimate calculated by the signal conversion unit 9 is input to a diagnostic frequency candidate extraction unit 11. The motor speed estimate is input to the calculation management unit 10 and is simultaneously input to a division unit 14 that uses a total gear ratio and an abnormality diagnosis unit 15.

[0021] In this embodiment, the block diagram is drawn on the assumption that all parts having a rotating shaft of the machine 7 are diagnosed, and therefore the motor speed estimate is used to diagnose parts arranged on the input shaft of the transmission 5 (rotating shaft 51, which is the same rotating shaft as the motor shaft). The output of the division unit 14 is used to diagnose parts arranged on the output shaft (rotating shaft 54) of the transmission 5 after all gear shifting has been completed. Note that information on the total gear ratio may also be obtained from a nameplate installed on the transmission 5, similar to the number of motor poles.

[0022] Next, calculation management unit 10, to which the motor speed estimate has been input, also inputs, from delay unit 13, the number of gears in transmission 5 and the diagnostic frequency output from diagnostic frequency selection unit 12 one step earlier (the frequency after the previous gear shift. Management of calculation steps is performed by calculation management unit 10). Then, it outputs to diagnostic frequency candidate extraction unit 11 the input frequency W before the gear shift, which is information necessary for calculating the frequency after deceleration to be estimated by diagnostic frequency candidate extraction unit 11, and the number of gears N indicating which gear, counted from the output shaft, is being calculated.

[0023] Furthermore, the diagnostic frequency candidate extraction unit 11, to which the total gear ratio, the torque current estimate, the motor speed estimate, the input frequency W, and the number of stages N are input, outputs a first diagnostic frequency candidate group and a second diagnostic frequency candidate group. Both the first and second diagnostic frequency candidate groups have one or more frequencies. In addition, although the frequency candidate groups are limited to two in this embodiment, the diagnostic frequency candidate extraction unit 11 may extract three or more frequency candidate groups.

[0024] The diagnostic frequency candidate extraction unit 11 calculates the frequency of the rotating shaft after shifting in the current gear stage based on the speed of the motor 4 (e.g., motor speed estimate), the gear ratio (total gear ratio) of the transmission 5, the current gear stage (stage number N) of the transmission 5, and the input frequency W of the current gear stage (stage number N), and extracts one or more frequencies (see FIG. 14 described later) as a second diagnostic frequency candidate group from a frequency spectrum obtained from current information (e.g., torque current estimate) regarding the motor 4 based on the frequency of the rotating shaft after shifting. The diagnostic frequency candidate extraction unit 11 is also configured to extract one or more frequencies (see FIG. 14 described later) as a first diagnostic frequency candidate group from a frequency spectrum obtained from current information (e.g., torque current estimate) regarding the motor 4 based on the meshing frequency of the gears constituting the current gear stage.

[0025] This makes it possible to accurately and automatically extract vibration frequency components for diagnosing abnormalities in rotating parts such as the rotating shaft and gears of the transmission 5 from the current information regarding the motor 4, which has a complex superposition of mechanical and electrical vibrations.

[0026] The signal conversion unit 9 is configured to estimate the speed of the motor 4 by dividing a frequency obtained by analyzing current information (e.g., a motor speed estimate) related to the motor 4 by the number of poles of the motor 4. In this manner, the motor speed estimate can be obtained from the current information related to the motor 4.

[0027] Finally, the diagnostic frequency selection unit 12 compares the first diagnostic frequency candidate group with the second diagnostic frequency candidate group, selects a frequency component that is common to the two diagnostic frequency candidate groups, and outputs it as a diagnostic frequency. The frequency component that is common to the two diagnostic frequency candidate groups is a frequency that satisfies a specific relationship among the frequencies obtained from the two diagnostic frequency candidate groups.

[0028] In this way, the diagnostic frequency selection unit 12 can accurately select a diagnostic frequency by selecting a frequency that satisfies a specific relationship as a diagnostic frequency from the frequencies obtained from the first diagnostic frequency candidate group and the second diagnostic frequency candidate group.

[0029] Here, the diagnostic frequency selection unit 12 can estimate a diagnostic frequency for each of the rotating shafts 51 to 54 (target shafts) to be diagnosed in the transmission 5, and store or output the diagnostic frequency in a memory (not shown). From here, each processing block, particularly the signal conversion unit 9, the calculation management unit 10, the diagnostic frequency candidate extraction unit 11, and the diagnostic frequency selection unit 12, will be described in detail.

[0030] [Signal conversion section] First, the signal conversion unit 9 will be described in detail with reference to FIG. FIG. 2 is a block diagram showing an example of the configuration of the signal conversion unit 9 according to the first embodiment. The signal conversion unit 9 includes a W-phase current generation unit 201 , a three-phase to two-phase conversion unit 202 , a phase calculation unit 203 , a coordinate conversion unit 207 , and a division unit 208 .

[0031] The signal conversion unit 9 is a processing block that converts the motor current, which is a two-phase AC signal, into a torque current estimate and a motor speed estimate, which are DC amounts. Here, the DC amount refers to a signal that is a constant value if there is no change in the load. The torque current estimate and motor speed estimate described below can be treated as DC amounts because the fundamental frequency (power supply frequency) of the motor current (phase current), which is an AC amount, has been removed. The power supply frequency is, for example, the frequency of the driving power supply 1, and can be the frequency of a commercial power supply (50 Hz, 60 Hz).

[0032] In this way, converting the motor current to a DC amount makes it easier to extract mechanical load fluctuations such as vibration. Another advantage is that vibration frequency components can be extracted at the same frequency as when handled by a vibration sensor. When analyzing the frequency spectrum of a signal, it is desirable for the rotation speed (frequency) to be constant, i.e., a DC amount.

[0033] (First processing example of the signal conversion unit) First, a conversion processing method using current phase will be described as the first processing method of the signal conversion unit 9. First, the U-phase current Iu and V-phase current Iv acquired by the current sensors 2 and 3 are input to the W-phase current generation unit 201. This is processing to obtain three-phase currents when the measured current is two-phase, and is not necessary when currents are acquired in all three phases. The W-phase current generation unit 201 performs processing shown in the following equation (1) to obtain the W-phase current Iw.

[0034] [Number 1] Iw = -(Iu + Iv) (1)

[0035] Next, the three-phase current is input from the W-phase current generation unit 201 to the three-phase to two-phase conversion unit 202, which performs the processes shown in the following equations (2) and (3). As a result, Iα and Iβ are obtained as orthogonal two-axis current components based on the α-axis and β-axis.

[0036] [Number 2] Iα=(2 / 3){Iu-Iv / 2-Iw / 2} ····(2) [Number 3] Iβ=(1 / √3){Iv-Iw} ····(3)

[0037] Then, the phase required for coordinate transformation (conversion to DC current) of the orthogonal two-axis current components based on the α-axis and β-axis is calculated by the phase calculation unit 203. The phase calculation unit 203 is composed of an instantaneous phase calculation unit 204, a PLL (Phase Locked Loop) unit 205, and an integration unit 206. Among these, the instantaneous phase calculation unit 204 performs the process shown in the following equation (4) to calculate the instantaneous phase θi * Calculate.

[0038] [Number 4] θi * =tan -1 (Iβ / Iα) (4)

[0039] Instantaneous phase θi *is passed through a feedback loop consisting of a PLL unit 205 and an integrator unit 206, and finally, a coordinate transformation phase θi is generated in the integrator unit 206. * The difference between this and the coordinate transformation phase θi output from the integrator 206 is calculated, and then this is input to the PLL unit 205 which performs phase synchronization processing. The output of the PLL unit 205 is then input to the integrator 206, where it is added sequentially. The value of this coordinate transformation phase θi becomes an estimate of the rotor position of the motor 4. The PLL unit 205 which performs phase synchronization processing can also be considered a phase storage unit which stores phase information.

[0040] In this process, the electrical speed estimate (i.e., the power supply frequency) Wi is obtained by the PLL unit 205. Since this feedback loop has a role of removing noise, if the instantaneous phase θi * If noise (electrical and mechanical noise) is not a concern, the instantaneous phase θi * It is not necessary to pass the instantaneous phase θi through the feedback loop described above. For example, * If the magnitude of the noise is smaller than a predetermined value, the feedback process is not performed. That is, the adder 209, the PLL unit 205, and the integrator 206 are not required. The configuration of this phase calculation unit 203 is also described in the specification of International Publication No. 2019 / 049188.

[0041] Then, the orthogonal two-axis current components Iα, Iβ based on the α-axis and β-axis calculated by the three-phase to two-phase conversion unit 202 and the coordinate transformation phase θi calculated by the phase calculation unit 203 are input to the coordinate transformation unit 207, and coordinate transformation is performed in the coordinate transformation unit 207. The coordinate transformation is a process of calculating the DC amount Ia of the current related to the motor 4, as shown in the following equation (5). The DC amount Ia is an active current component. The reactive current component Iz is not used here.

[0042] [Number 5] Ia=Iα·cos(θi)+Iβ·sin(θi) ····(5)

[0043] The DC amount Ia calculated in this way and the electric speed estimate value Wi output from the phase calculation unit 203 are DC amounts. Here, in the division unit 208, when the electric speed estimate value Wi is divided by the number of motor poles, an estimate value of the motor speed (rotation frequency of the motor shaft) is obtained. In addition, since the DC amount Ia is similar to the time change of the torque current used in motor control, in this specification, the DC amount Ia is described as the "torque current estimate value". This calculation method is based on an implementation model and can be applied in any situation, even if the motor 4 is a constant speed or a variable speed.

[0044] (Second processing example of the signal conversion unit) Next, the second processing method of the signal conversion unit 9 will be described with reference to FIG. FIG. 3 is a block diagram showing another example of the configuration of the signal conversion unit 9 according to the first embodiment. The signal conversion unit 9A shown in Fig. 3 uses the same calculation method as the signal conversion unit 9 shown in Fig. 2 up to the calculation of Iα and Iβ by the W-phase current generation unit 201 and the three-phase to two-phase conversion unit 202. To calculate the torque current estimate, the signal conversion unit 9A executes the process of the following equation (6) using Iα and Iβ in a processing block 312 after the three-phase to two-phase conversion unit 202. That is, the root mean square of Iα and Iβ is calculated.

[0045] [Number 6] Ia = √(Iα 2 +Iβ 2 ) ····(6)

[0046] On the other hand, in calculating the motor speed estimate, a signal (time axis signal) of one phase, either the U-phase current Iu or the V-phase current Iv, is converted by the frequency analysis unit 313 into a frequency axis signal as shown in Fig. 4. As a result, the frequency at which the amplitude becomes a peak value is extracted by the peak frequency extraction unit 314 from the U-phase current Iu or the V-phase current Iv.

[0047] Fig. 4 is a diagram showing an example of a waveform obtained by frequency analysis of a phase current of the mechanical device 7 (motor 4). In Fig. 4, the horizontal axis represents frequency, and the vertical axis represents amplitude. Since the peak frequency of the phase current is the frequency of the power supply that drives the motor 4, the motor speed estimate can be calculated by dividing this peak frequency by the number of motor poles in the division unit 315. This method is preferably used when the motor 4 is operating at a constant speed. As described above, the FFT (Fast Fourier Transform) used in the frequency analysis unit 313 improves the analysis accuracy when the rotation speed is constant.

[0048] The configuration and operation of the signal conversion unit 9 that converts current information related to the motor 4 from AC to DC can use known technology, for example, as described in the specification of International Publication No. 2019 / 049188.

[0049] [Calculation management department] Next, the calculation management unit 10 will be described with reference to FIG. The calculation management unit 10 is a block that controls the processing of the diagnostic frequency estimation unit 8, and manages the calculation steps and information required for the calculation.

[0050] 5 is a flowchart showing an example of the procedure of processing by the calculation management unit 10. When the calculation management unit 10 starts calculation for the first time (S1), information on the number of gears of the transmission 5 is input to the variable N (S2). At that time, the calculation management unit 10 sets a flag S to 1, which indicates that this is the first estimation calculation.

[0051] Here, the transmission 5 will be described with reference to FIG. FIG. 6 is a diagram showing an example of the configuration of the transmission 5. As an example, when estimating the frequency of the rotating shafts 51 to 54 of the transmission 5 shown in Fig. 6, the number of gears N is 3 (three gears). The gears are counted from the output shaft side. In each gear, a front gear and a rear gear, which have different numbers of teeth, mesh and rotate, causing the rotation frequency of the rotating shafts 52 to 54 to change.

[0052] Next, the calculation management unit 10 checks whether the number of stages N is 1 (S3). Since N=3 in this example, the result of the determination in step S3 is NO, and the process proceeds to step S4.

[0053] Next, the calculation management unit 10 checks whether or not this is the first calculation by checking the flag S (S4). Currently, the flag S is 1, so the determination in step S4 is Yes. Next, in step S8, the calculation management unit 10 sets the flag S to 0, and sets the input frequency W before the gear shift to be input to the diagnostic frequency candidate extraction unit 11 to the motor speed estimate value estimated by the signal conversion unit 9 (S8).

[0054] 6, the input frequency W is a step for calculating the frequency of the rotating shaft 52 (second shaft from the left) after the current first-stage speed change, and the input frequency W used at that time is the frequency of the rotating shaft 51 before the speed change, that is, the motor speed estimate value. Therefore, in step S8, the input frequency W is set to the motor speed estimate value.

[0055] After the process of step S8, the calculation management unit 10 outputs the input frequency W and the number of stages N (S6). Next, in step S7, the calculation management unit 10 updates the number of stages N (N=N-1), and the diagnosis frequency candidate extraction unit 11 estimates the diagnosis frequency (estimated value 1 in FIG. 6). After the process of step S7, the process returns to step S3.

[0056] In the second loop (estimating the frequency of the third rotating shaft 53 from the left in FIG. 6), N=2 and S=0, so the process proceeds to step S5 after NO judgments in steps S3 and S4. Here, the calculation management unit 10 sets the input frequency W to the diagnostic frequency calculated one step before (since the current step is estimating the rotation frequency of the third shaft from the left, the estimated value 1 in FIG. 6 becomes the diagnostic frequency one step before).

[0057] Then, the calculation management unit 10 proceeds to steps S6 and S7 to update the number of stages N (N=N-1), and the diagnostic frequency candidate extraction unit 11 estimates the diagnostic frequency (estimated value 2 in FIG. 6). After the process of step S7, the process returns to step S3.

[0058] Then, in the third loop, since N=1, the calculation management unit 10 judges YES in step S3 and ends the estimation of the diagnostic frequency by the diagnostic frequency candidate extraction unit 11 (S9). After step S9 ends, this flowchart ends (S10). Note that since the rotational frequencies of the input shaft (rotating shaft 51) and output shaft (rotating shaft 54) of the transmission 5 can be calculated from the motor speed estimate value and the total gear ratio (total reduction ratio), the diagnostic frequency candidate extraction unit 11 does not perform estimation calculation.

[0059] [Diagnostic frequency candidate extraction section] Next, the diagnostic frequency candidate extraction unit 11 will be described with reference to FIG. FIG. 7 is a block diagram showing an example of the configuration of the diagnostic frequency candidate extraction unit 11 according to the first embodiment. The diagnostic frequency candidate extraction unit 11 extracts the diagnostic frequency candidate group using two different methods. The details of the different methods will be described later, but the key point is that the method uses the principle that since the rotating shafts 51 to 54 always rotate with minute misalignment and eccentricity, in a mechanism having gears, the influence of such misalignment appears in both the rotation frequency and the sidebands of the meshing frequency.

[0060] As shown in FIG. 7, the diagnostic frequency candidate extraction unit 11 is made up of a frequency analysis unit 701, a total gear ratio recalculation unit 702, a gear ratio division unit 703, a multiplication unit 704, a frequency peak extraction unit 705, a multiplication unit 706, and a sideband peak extraction unit 707.

[0061] First, the torque current estimate input to the diagnostic frequency candidate extraction unit 11 is input to a frequency analysis unit 701, and converted from time axis information to frequency axis information using a technique such as FFT (Fast Fourier Transform). Frequency axis information of the torque current estimate, i.e., frequency spectrum information, is input from the frequency analysis unit 701 to a frequency peak extraction unit 705.

[0062] Next, information on the input frequency W before the shift, the motor speed estimate, and the total gear ratio is input to a total gear ratio recalculation unit 702. This total gear ratio recalculation unit 702 recalculates the total gear ratio from the gear for which the current diagnostic frequency is to be estimated to the final gear.

[0063] 6 as an example, for example, if the rotation frequency of the third rotating shaft 53 from the left is currently being estimated, the multiplied value of the gear ratio of the second gear and the gear ratio of the third gear becomes the new total gear ratio. On the other hand, if the rotation frequency of the second rotating shaft 52 from the left is being estimated, the total gear ratio input to the diagnostic frequency candidate extraction unit 11 can be used as it is. Therefore, the total gear ratio is recalculated as shown in the following formula (7).

[0064] [Number 7] Recalculated total gear ratio = total gear ratio / (W / estimated motor speed) (7)

[0065] The total gear ratio recalculated as described above is input from the total gear ratio recalculator 702 to the gear ratio divider 703 together with the gear number N indicating which gear is being calculated counting from the output shaft. Then, the gear ratio R of the current gear is estimated from the recalculated total gear ratio. That is, the gear ratio division is a part of the total gear ratio of the transmission 5, and represents a component (gear ratio R) obtained by dividing the total gear ratio. As a calculation method, for example, a table may be prepared containing candidates for the gear ratio R per gear based on the relationship between the recalculated total gear ratio and the gear number N, and the table may be used. For example, the table is stored in a non-volatile memory (not shown) provided in the gear ratio divider 703 or the diagnostic frequency candidate extractor 11.

[0066] The gear ratio R calculated by the gear ratio dividing unit 703 is multiplied by the input frequency W in the multiplying unit 704 and input to the frequency peak extracting unit 705 together with the analysis result of the frequency analyzing unit 701. The output of the multiplying unit 704 corresponds to the rotation frequency of the rotating shaft after shifting of the currently targeted gear. Note that the value of the gear ratio R output from the gear ratio dividing unit 703 does not have to be one, and the gear ratio R may be a value having a certain range.

[0067] The frequency peak extraction unit 705 searches for the numerical value calculated by the multiplication unit 704 from the frequency spectrum calculated by the frequency analysis unit 701. As a method, for example, one or more frequency peaks existing within a width of ±10% of the output value of the multiplication unit 704 may be extracted. Also, when the gear ratio R is calculated with a certain range by the gear ratio division unit 703, it is sufficient to extract one or more frequency peaks that fall within that range, and the extraction result is output as a second diagnosis frequency candidate group.

[0068] Meanwhile, the input frequency W is also input to a multiplication unit 706, where it is multiplied by the estimated number of teeth of the gear on the input side of the gear currently being calculated. This corresponds to calculating the frequency of meshing vibration (an example of mechanical vibration) generated from the gears. At this time, the estimated number of teeth may be calculated in advance from a plurality of design values ​​of the transmission, etc., and stored in a non-volatile memory (not shown) provided in the diagnostic frequency candidate extraction unit 11, etc. Also, the estimated number of teeth may not be one, but may have a certain range.

[0069] The output result from the multiplication unit 706 and the output result from the frequency analysis unit 701 (frequency spectrum of the torque current estimated value) are input to the sideband wave peak extraction unit 707. The sideband wave peak extraction unit 707 first searches for a meshing frequency from the frequency spectrum of the torque current estimated value. The search method is to search for a maximum peak within a range of, for example, ±10% of the output value of the multiplication unit 706. At this time, the sideband wave peak extraction unit 707 may search using a plurality of conditions as AND conditions, such as not being a harmonic of electrical noise, or may search using the above-mentioned plurality of conditions within a certain range if the output value of the multiplication unit 706 has such a range. Then, the sideband wave peak extraction unit 707 extracts a peak frequency present in a sideband wave of a determined meshing frequency (for example, within a range of ±10% of the meshing frequency) and outputs it as a first diagnosis frequency candidate group. Note that the number of frequencies to be extracted may be one or more. In addition, the conditions for the frequencies to be extracted from the sidebands of the meshing frequency are set in advance through testing or the like in a non-volatile memory (not shown) provided in the sideband peak extractor 707 or the diagnostic frequency candidate extractor 11.

[0070] [Diagnostic frequency selection section] Next, the diagnostic frequency selection unit 12 will be described with reference to FIG. The diagnostic frequency selection unit 12 (Fig. 1) compares the frequencies (second diagnostic frequency candidates) included in the second diagnostic frequency candidate group output from the diagnostic frequency candidate extraction unit 11 with the frequency obtained by subtracting the meshing frequency from the first diagnostic frequency candidate group and taking the absolute value, and outputs the frequency at which a specific relationship is established between the two diagnostic frequency candidate groups as a diagnostic frequency. The two frequencies at which this specific relationship is established have the relationship "frequency difference Δf = meshing frequency - (second diagnostic frequency candidate) × 2" or "frequency difference Δf = meshing frequency".

[0071] In this way, the frequency difference Δf (specific frequency) satisfies any one of the following relationships: Frequency difference Δf = meshing frequency of the meshing gears of the transmission 5 - (frequency extracted from the second diagnostic frequency candidate group x 2) Frequency difference Δf = meshing frequency of meshing gears

[0072] As a result, the diagnostic frequency selection unit 12 can extract a group of multiple diagnostic frequency candidates from a frequency range that is separated by a frequency difference Δf or more (specific frequency), and estimate a frequency that satisfies a specific relationship from among the frequencies obtained in the group of multiple diagnostic frequency candidates as the diagnostic frequency.

[0073] [Frequency spectrum including first diagnostic frequency candidate group and second diagnostic frequency candidate group] Fig. 14 is a diagram showing an example of a frequency spectrum of a torque current estimate including a first diagnostic frequency candidate group and a second diagnostic frequency candidate group. Fig. 14 shows an example of a frequency spectrum of a torque current estimate when specific numerical values ​​are applied to the machine 7.

[0074] Fig. 14 shows only the frequency spectrum of the first gear in a two-speed system with a total gear ratio of 1 / 4 and a gear ratio of each gear of 1 / 2. That is, this transmission has an input shaft, an output shaft, and a rotating shaft disposed between them. It is further assumed that the number of teeth of the gear on the input shaft is 30, the number of teeth of the gear that meshes with the gear on the input shaft is 60, the rotation speed of the input shaft is 10 Hz, the rotation speed of the rotating shaft that meshes with the input shaft after gear shifting is 5 Hz, and the meshing frequency of the first gear is 300 Hz.

[0075] When this embodiment is applied to a machine 7 under such conditions, the diagnostic frequency selection unit 12 selects 5 Hz from the second diagnostic frequency candidate group, and selects 295 Hz or 305 Hz from the first diagnostic frequency candidate group. In other words, it can be seen that the difference (specific frequency) between the frequencies extracted from the first and second diagnostic frequency candidate groups has the above-mentioned relationship. Then, the diagnostic frequency selection unit 12 selects 5 Hz extracted from the second diagnostic frequency candidate group as the diagnostic frequency for the rotating shaft meshing with the input shaft, and outputs it to the abnormality diagnosis unit 15.

[0076] In this way, the diagnostic frequency selection unit 12 selects a frequency that satisfies the above-mentioned specific relationship as a diagnostic frequency from among the frequencies included in the second diagnostic frequency candidate group. This allows the diagnostic frequency selection unit 12 to accurately and automatically select a diagnostic frequency from the second diagnostic frequency candidate group extracted by the diagnostic frequency candidate extraction unit 11 by utilizing two completely different phenomena that the mechanical effect of a mechanism having gears appears in both the rotation frequency and the sideband of the meshing frequency.

[0077] As shown in the specific example, in this embodiment, when there are two frequency candidate groups, the first diagnostic frequency candidate group is made up of one or more frequencies extracted from "sideband waves of the meshing frequency (e.g., 300 Hz) of the meshing gears of the transmission 5". The second diagnostic frequency candidate group is made up of one or more frequencies (e.g., 5 Hz) extracted from "other than the sideband waves of the meshing frequency (e.g., 300 Hz) of the meshing gears of the transmission 5".

[0078] [Abnormality diagnosis section] Finally, the abnormality diagnosis unit 15 will be described. The abnormality diagnosis unit 15 uses the diagnostic frequency estimated by the diagnostic frequency estimation unit 8 to perform abnormality diagnosis (e.g., calculate the degree of abnormality) of the transmission 5. For example, the abnormality diagnosis may involve inputting the amplitude component of the diagnostic frequency into a previously prepared model to calculate an evaluation value (continuous value or discrete value) indicating an abnormal state, or outputting a result (e.g., degree of abnormality) of comparing the amplitude component directly with a threshold value. When a model is used, a model that has learned a normal state or a model that has learned abnormal and normal states may be used, and may be constructed using a regression model, a classification model, a cluster model, a neural network, or the like.

[0079] Furthermore, the amplitude component of the above-mentioned diagnostic frequency may be an amplitude component of a frequency obtained by multiplying the diagnostic frequency by a coefficient. The coefficient may be, for example, a numerical value resulting from the shape of the bearing of the rotating shaft or the number of teeth of a gear, or the diagnostic frequency may be multiplied by an integer or fractional value. Furthermore, the abnormality diagnosis unit 15 may use multiple input values ​​of the diagnostic frequency, or may use a single value. Furthermore, there may be multiple models for calculating the degree of abnormality, for example, for each diagnostic part of the diagnosis target (here, the transmission 5).

[0080] The transmission monitoring system 100 according to the first embodiment configured as described above makes it possible to accurately and automatically estimate vibration frequency components for diagnosing an abnormality in a rotating part (transmission 5) from the motor current on which mechanical and electrical noise are superimposed, using only information on the motor current, total gear ratio, number of gears, and number of motor poles. Furthermore, by using the diagnostic frequency components, the transmission monitoring system according to this embodiment is expected to improve diagnostic accuracy and reduce the time required to build the transmission monitoring system.

[0081] <Second embodiment> In the second embodiment of the present invention, a transmission monitoring system is described which estimates the vibration frequency (diagnosis frequency) required to diagnose rotating parts and calculates the degree of abnormality based on information on one-phase motor current, the total gear ratio and number of gears of the mechanical device 7, and the number of poles of the motor 4.

[0082] [Configuration of the transmission monitoring system] FIG. 8 is a block diagram showing an example of the configuration of a transmission monitoring system according to the second embodiment of the present invention. In the second embodiment, a duplicated description will be omitted for the parts that perform the same configuration and processing as in the first embodiment. A transmission monitoring system 100A according to the second embodiment differs from the transmission monitoring system 100 according to the first embodiment (FIG. 1) in that only one phase of the motor current is used as the current information related to the motor 4. For this reason, the transmission monitoring system 100A includes a signal conversion unit 809 instead of the signal conversion unit 9. In this embodiment, it is assumed that the U-phase current Iu is acquired by the current sensor 2. The phase of the current to be acquired may be any of the U-phase, V-phase, and W-phase. The acquired motor current is input to the signal conversion unit 809.

[0083] [Signal conversion section] Next, details of the signal conversion unit 809 will be described with reference to FIG. FIG. 9 is a block diagram showing an example of the configuration of the signal conversion unit 809 according to the second embodiment. The signal conversion unit 809 performs a process of calculating a torque current estimate value and a motor speed estimate value, similarly to the first embodiment. The input U-phase current Iu is input to an envelope detection unit 901, which calculates a torque current estimate value.

[0084] Examples of methods for processing the envelope include the Hilbert transform. The value obtained by envelope processing of the phase current has alternating positive and negative AC components removed, resulting in a DC amount that changes similarly to the torque current. As a result, the value obtained by envelope processing of the phase current can be treated as a torque current estimate. Meanwhile, the calculation of the motor speed estimate is the same as the method by the signal conversion unit 9 shown in FIG. 3, and therefore a description thereof will be omitted.

[0085] According to the transmission monitoring system 100B according to the second embodiment described above, the number of current sensors can be reduced compared to the first embodiment, making it possible to reduce the cost of constructing the transmission monitoring system.

[0086] <Third embodiment> In the third embodiment of the present invention, another transmission monitoring system will be described which estimates the vibration frequency (diagnosis frequency) required for diagnosing rotating parts and calculates the degree of abnormality based on information on one-phase motor current, the total gear ratio and number of gears of the mechanical device 7, and the number of poles of the motor 4. In other words, the third embodiment can be said to be a modified example of the second embodiment.

[0087] [Configuration of the transmission monitoring system] FIG. 10 is a block diagram showing an example of the configuration of a transmission monitoring system according to the third embodiment of the present invention. In the third embodiment, the same configuration and processing as those of the first and second embodiments will not be described. The transmission monitoring system 100B according to the third embodiment differs from the transmission monitoring systems 100 and 100A according to the first and second embodiments in two points. The first point is that the signal conversion unit 1009 outputs the phase current itself instead of the torque current estimated value, and the second point is that the processing method of the diagnostic frequency candidate extraction unit 1011 is different.

[0088] [Signal conversion section] Next, details of the signal conversion unit 1009 will be described with reference to FIG. FIG. 11 is a block diagram showing an example of the configuration of the signal conversion unit 1009 according to the third embodiment. The signal conversion unit 1009 outputs the phase current as it is, without converting the motor current into a DC current as in the first and second embodiments. Fig. 11 shows a configuration in which the U-phase current Iu acquired by the current sensor 2 is output to the diagnostic frequency candidate extraction unit 1011 as it is.

[0089] [Diagnostic frequency candidate extraction section] Next, the diagnostic frequency candidate extraction unit 1011 will be described in detail with reference to FIG. FIG. 12 is a block diagram showing an example of the configuration of a diagnostic frequency candidate extraction unit 1011 according to the third embodiment. In the diagnostic frequency candidate extraction unit 1011 to which the phase current is input, as shown in FIG. 12, the same processing as in the first embodiment is executed except for the frequency peak extraction unit (for phase current) 1205 and the sideband peak extraction unit (for phase current) 1207.

[0090] In the frequency peak extraction unit 1205, since the search target is the frequency spectrum of the phase current, the search is performed using a value obtained by adding the power supply frequency to the value output from the multiplication unit 704. As described above, the output from the multiplication unit 704 corresponds to the rotational frequency of the rotating shaft after shifting of the currently targeted gear. Similarly, in the sideband peak extraction unit 1207, a search is performed using a value obtained by adding the power supply frequency to the value output from the multiplication unit 706. In other words, the information on the frequency axis in FIG. 14 described in the first embodiment also appears shifted by the power supply frequency.

[0091] For example, in the first embodiment, the frequency peak extraction unit 705 (FIG. 7) selects "5 Hz" extracted from the second diagnostic frequency candidate group shown in FIG. 14 as the vibration frequency. If the power supply frequency is 50 Hz, the power supply frequency of 50 Hz is added to this 5 Hz to obtain "55 Hz." Also, in FIG. 14, the meshing frequency of "300 Hz" is displayed as an example of a frequency in the first vibration frequency candidate group. If the meshing frequency is 300 Hz, the power supply frequency of 50 Hz is added to it to obtain "350 Hz."

[0092] According to the transmission monitoring system 100B of the third embodiment configured as described above, the number of current sensors can be reduced compared to the first embodiment, making it possible to reduce the cost of constructing the transmission monitoring system. Furthermore, in this embodiment, the signal conversion process can be simplified compared to the second embodiment. Therefore, it is possible to reduce the processing load of the transmission monitoring system.

[0093] According to the transmission monitoring systems 100, 100A, 100B of the first to third embodiments described above, the signal conversion units 9, 809, 1009 can acquire current information (motor current) related to the motor 4 from a current sensor installed in at least one phase of the motor 4 and perform diagnosis.

[0094] Also, as shown in the specific example, in this embodiment, when there are two frequency candidate groups, the first diagnostic frequency candidate group is composed of one or more frequencies extracted from "sideband waves of a frequency obtained by adding the meshing frequency of the meshing gears of the transmission 5 (e.g., 300 Hz) to the power supply frequency of the drive power source 1 of the motor 4 (e.g., 50 Hz)". Also, the second diagnostic frequency candidate group is composed of one or more frequencies (e.g., 55 Hz) extracted from "other than the sideband waves of a frequency obtained by adding the meshing frequency of the meshing gears of the transmission 5 (e.g., 300 Hz) to the power supply frequency of the drive power source 1 of the motor 4 (e.g., 50 Hz)".

[0095] <Fourth embodiment> In a fourth embodiment of the present invention, a transmission monitoring system is described which estimates the vibration frequency (diagnosis frequency) required for diagnosing rotating parts and calculates the degree of abnormality based on information on the torque current, the total gear ratio and number of gears of the mechanical device, and the motor speed.

[0096] [Configuration of the transmission monitoring system] FIG. 13 is a block diagram showing an example of the configuration of a transmission monitoring system according to the fourth embodiment of the present invention. In the fourth embodiment, a duplicated description will be omitted for the parts that perform the same configuration and processing as those of the first to third embodiments. A transmission monitoring system 100C according to the fourth embodiment differs from the transmission monitoring systems 100 to 100B according to the first to third embodiments in that information on the torque current and motor speed, which are already DC values, is acquired from a driving power source 1301 (inverter) as current information on the motor 4. The driving power source 1301 of the mechanical device 1307 has a configuration similar to that of the driving power source 1 (FIG. 1), except that the driving power source 1301 outputs the above-mentioned information on the torque current and motor speed to the diagnostic frequency candidate extraction unit 11.

[0097] Therefore, in this embodiment, the signal conversion units 9, 809, 1009 that are present in the transmission monitoring systems 100 to 100B according to the first to third embodiments are not required. Torque current information is directly input from the driving power supply 1301 to the diagnostic frequency candidate extraction unit 11. In addition, motor speed information is directly input from the driving power supply 1301 to the diagnostic frequency candidate extraction unit 11, the calculation management unit 10, the division unit 14, and the abnormality diagnosis unit 15. Note that the contents of the other processing blocks are the same as those described in the first and second embodiments, and therefore description thereof will be omitted.

[0098] According to the transmission monitoring system 100C according to the fourth embodiment described above, the number of current sensors can be reduced compared to the first to third embodiments, and the processing load of the transmission monitoring system can be reduced.

[0099] <Summary of the First to Fourth Embodiments> As described above, the transmission monitoring systems according to the first to fourth embodiments of the present invention are transmission monitoring systems that monitor a transmission driven by a motor, and include a diagnostic frequency estimation unit and an abnormality diagnosis unit. The diagnostic frequency estimation unit is configured to extract a group of multiple diagnostic frequency candidates from a frequency range that is separated by a specific frequency (frequency difference Δf) or more using at least current information related to the motor, a gear ratio of the transmission, and the number of stages of the transmission, and to estimate a frequency that satisfies a specific relationship from the frequencies obtained in the group of multiple diagnostic frequency candidates as a diagnostic frequency. The abnormality diagnosing unit is configured to diagnose an abnormality in the transmission by using at least one of the diagnostic frequencies estimated by the diagnostic frequency estimating unit.

[0100] According to the transmission monitoring systems of the first to fourth embodiments described above, it is possible to accurately and automatically estimate vibration frequency components for diagnosing abnormalities in rotating parts of a transmission from current information (motor current, torque current, etc.) relating to a motor on which mechanical and electrical vibrations are superimposed in a composite manner. Furthermore, the transmission monitoring systems of each embodiment are expected to improve diagnostic accuracy and reduce the time required to build the transmission monitoring system by using the diagnostic frequency components.

[0101] <Modification> It should be noted that the present invention is not limited to the above-described embodiments, and various other applications and modifications are possible without departing from the gist of the present invention as set forth in the claims.

[0102] For example, each of the above-mentioned embodiments describes the configuration of a monitoring system in detail and specifically in order to clearly explain the present invention, and is not necessarily limited to having all of the components described. Also, it is possible to replace a part of the configuration of one embodiment with a component of another embodiment. Also, it is possible to add a component of another embodiment to the configuration of one embodiment. Also, it is possible to add, replace, or delete other components from part of the configuration of each embodiment.

[0103] In addition, in each of the above-described embodiments, the control lines and information lines are those that are considered necessary for the explanation, and not all of the control lines and information lines in the product are necessarily shown. In reality, it may be considered that almost all of the components are connected to each other.

[0104] Further, each of the configurations, functions, processing units, etc. described in each embodiment may be realized in part or in whole by hardware, for example, by designing them as an integrated circuit. A broad processor device such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit) may be used as the hardware. Furthermore, in the transmission monitoring system according to each of the above-mentioned embodiments, the processing performed by a certain processing unit may be realized by a single piece of hardware, or may be realized by distributed processing by a plurality of pieces of hardware.

[0105] Furthermore, each of the above components, functions, processing units, etc. may be realized by software, in which a processor in a computer interprets and executes a program that realizes each function. Information such as the program, table, and file that realizes each function can be stored in a recording device such as a memory, a hard disk, or an SSD (Solid State Drive), or in a recording medium such as an IC card, an SD card, or an optical disk. [Explanation of symbols]

[0106] 1...driving power supply, 2...U-phase current sensor, 3...V-phase current sensor, 4...motor 4...speed change device, 6...load device, 7,807,1307...machine device, 8,808,1008,1308...diagnosis frequency estimation unit, 9,9A,809,1009...signal conversion unit, 10...calculation management unit, 11,1011...diagnosis frequency candidate extraction unit, 12...diagnosis frequency selection unit 12...delay unit, 14...division unit, 15...abnormality diagnosis unit, 100,100A,100B,100C...speed change device monitoring system

Claims

1. A transmission monitoring system for monitoring a transmission driven by a motor, comprising: a diagnostic frequency estimation unit that estimates a diagnostic frequency using at least current information related to the motor, a gear ratio of the transmission, and a number of stages of the transmission; an abnormality diagnosis unit that diagnoses an abnormality in the transmission by using at least one of the diagnostic frequencies estimated by the diagnostic frequency estimation unit, The diagnostic frequency estimation unit is a frequency of the rotating shaft after shifting at the current gear stage is calculated based on the speed of the motor, the gear ratio of the transmission, the current gear stage of the transmission, and the input frequency of the current gear stage; one or more frequencies are extracted as a second diagnostic frequency candidate group from a frequency spectrum obtained from current information about the motor based on the frequency of the rotating shaft after shifting; and one or more sideband frequencies of the meshing frequency are extracted as a first diagnostic frequency candidate group from a frequency spectrum obtained from current information about the motor based on a meshing frequency of a gear that constitutes the current gear stage; A diagnostic frequency is selected from one or more frequencies extracted as the second diagnostic frequency candidate group based on a difference between the meshing frequency and one or more sideband frequencies of the meshing frequency extracted as the first diagnostic frequency candidate group. Transmission monitoring system.

2. The current information about the motor is obtained from a current sensor installed in at least one phase of the motor.

2. The transmission monitoring system of claim 1.

3. The current information regarding the motor is a torque current that can be obtained from a drive power supply that drives the motor.

2. The transmission monitoring system of claim 1.

4. The first diagnostic frequency candidate group is composed of one or more frequencies extracted from sideband waves of meshing frequencies of gears constituting the current gear shift stage, The second diagnostic frequency candidate group is composed of one or more frequencies extracted from other than the sidebands of the meshing frequency of the gears constituting the current gear shift stage. A transmission monitoring system according to claim 2 or 3.

5. The first group of diagnostic frequency candidates is composed of one or more frequencies extracted from sideband waves of a frequency obtained by adding a power supply frequency of a drive power source for the motor to a meshing frequency of gears constituting the current gear stage, The second diagnostic frequency candidate group is composed of one or more frequencies extracted from other than the sidebands of a frequency obtained by adding the meshing frequency of the gears constituting the current gear stage to the power supply frequency of the drive power source of the motor.

3. The transmission monitoring system of claim 2.

6. When an absolute value of a difference between a frequency extracted from the first diagnostic frequency candidate group and a frequency extracted from the second diagnostic frequency candidate group is a frequency difference Δf, Δf = meshing frequency of the gear constituting the current gear stage - (frequency extracted from the second diagnosis frequency candidate group x 2) Or, Δf = meshing frequency of the gears constituting the current gear shift stage The relationship that 5. The transmission monitoring system of claim 4.

7. When an absolute value of a difference between a frequency extracted from the first diagnostic frequency candidate group and a frequency extracted from the second diagnostic frequency candidate group is a frequency difference Δf, Δf = meshing frequency of the gear constituting the current gear stage - (frequency extracted from the second diagnosis frequency candidate group x 2) Or, Δf = meshing frequency of the gears constituting the current gear shift stage The relationship that 6. A transmission monitoring system according to claim 5.

8. The abnormality diagnosis unit is The amplitude component of the diagnostic frequency is input to a model constructed by any one of a regression model, a classification model, a cluster model, and a neural network model to calculate the degree of abnormality, or the amplitude component of the diagnostic frequency is compared with a threshold value to calculate the degree of abnormality of the transmission.

2. The transmission monitoring system of claim 1.

9. The diagnostic frequency estimation unit is The speed of the motor is estimated by dividing a frequency obtained by analyzing current information about the motor by the number of poles of the motor.

2. The transmission monitoring system of claim 1.

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