Degradation diagnosis device, motor system, and degradation diagnosis method

Abstract

To provide a degradation diagnosis device capable of diagnosing the degradation state of a motor.SOLUTION: A degradation diagnosis device for diagnosing degradation of a motor includes: an acquisition unit that acquires characteristic values related to the motor in each sample cycle; and a processing unit that processes the characteristic values acquired by the acquisition unit. The processing unit executes the steps of: (a) acquiring the characteristic values related to the motor as inspection data; (b) updating a variation coefficient of the inspection data; (c) updating an average value of the variation coefficient; and (d) updating an absolute value of a difference between the variation coefficient and the average value of the variation coefficient.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an abnormality detection device including a first sound collection unit that collects ambient sound including the sound emitted by a rotating mechanism rotating at a predetermined rotation period and obtains a first sound pressure of the ambient sound. Further, Patent Document 1 discloses that the abnormality detection device calculates a first sound quality index of the ambient sound using the first sound pressure, and includes a calculation unit that obtains a time waveform of the first sound quality index, and a first detection unit that detects an abnormal state of the rotating mechanism using the time waveform of the first sound quality index. Furthermore, Patent Document 1 discloses that the first detection unit in the abnormality detection device calculates an average value of a time change amount of the first sound quality index and a standard deviation of the time change amount of the first sound quality index, and calculates a coefficient of variation obtained by dividing the standard deviation by the average value. Still further, Patent Document 1 discloses that the first detection unit in the abnormality detection device detects an abnormal state of the rotating mechanism when the coefficient of variation is equal to or greater than a predetermined threshold value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a motor control device, it is required to diagnose the deterioration state of a motor.

[0005] The present disclosure provides a deterioration diagnosis device for diagnosing the deterioration state of a motor.

Means for Solving the Problems

[0006] In one aspect of the present disclosure, there is provided a deterioration diagnosis device for diagnosing the deterioration of a motor, comprising: an acquisition unit that acquires characteristic values related to the motor at each sampling period; and a processing unit that processes the characteristic values acquired by the acquisition unit, wherein the processing unit executes: (a) a procedure for acquiring characteristic values related to the motor as inspection data; (b) a procedure for updating the coefficient of variation of the inspection data; (c) a procedure for updating the average value of the coefficient of variation; and (d) a procedure for updating the absolute deviation of the difference between the coefficient of variation and the average value of the coefficient of variation.

Effect of the Invention

[0007] According to the motor deterioration diagnosis device of the present disclosure, the deterioration state of the motor can be diagnosed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

DETAILED DESCRIPTION OF THE INVENTION

[0009] ≪MOTOR SYSTEM≫ Hereinafter, with reference to the drawings, a motor system in which the motor control device according to the present embodiment is used will be described.

[0010] FIG. 1 is a diagram showing an outline of a motor system 1 in which a motor control device 100, which is an example of the motor control device according to the present embodiment, is used. Note that the motor control device 100 is an example of a deterioration diagnosis device for diagnosing the deterioration of a motor.

[0011] The motor system 1 includes a motor 10 and a motor drive control system 20. The motor 10 is used, for example, to rotate a fan. The motor drive control system 20 drives and controls the motor 10.

[0012] The motor drive control system 20 includes a motor control device 100 and a host device 200.

[0013] <MOTOR CONTROL DEVICE 100> The motor control device 100 includes a motor drive circuit 101, a sensor unit 102, and an FG (Frequency Generator) signal generation unit 103. The motor control device 100 also includes a power supply voltage measurement unit 110, a drive control signal generation unit 120, a communication unit 130, a current measurement unit 140, a rotation speed measurement unit 150, a deterioration diagnosis control unit 160, and a data management unit 170.

[0014] Note that the drive control signal generation unit 120, the rotational speed measurement unit 150, the deterioration diagnosis control unit 160, and the data management unit 170 in the motor control device 100 are realized by, for example, a program processing device (computer). More specifically, the program processing device includes a processor such as a CPU (Central Processing Unit), and various storage devices such as a RAM (Random Access Memory) and a ROM (Read Only Memory). Further, the program processing device includes peripheral circuits such as a counter (timer), an AD (Analog-to-digital) conversion circuit, a DA (Digital-to-analog) conversion circuit, a clock generation circuit, and an input / output I / F (Interface) circuit. For example, each of the processor, the storage device, and the peripheral circuit is connected to each other via a bus or a dedicated line. The program processing device is, for example, a microcontroller. In the program processing device, the CPU executes various arithmetic processes according to a program stored in the memory, thereby realizing the processes.

[0015] [Motor drive circuit 101] The motor drive circuit 101 drives the motor 10 based on the drive control signal Ctl generated by the drive control signal generation unit 120. The motor drive circuit 101 includes, for example, a pre-drive circuit and an inverter circuit.

[0016] The pre-drive circuit generates an output signal for driving the inverter circuit based on the drive control signal Ctl. The pre-drive circuit outputs the generated output signal to the inverter circuit. The pre-drive circuit generates and outputs, for example, a drive signal for driving each switch element of the inverter circuit based on the drive control signal Ctl.

[0017] The inverter circuit outputs a drive signal to the motor 10 based on the output signal output from the pre-drive circuit. The drive signal output by the inverter circuit energizes the coil provided in the motor 10. The inverter circuit is, for example, a pair of series circuits of two switch elements provided at both ends of a DC power supply, for example, transistors such as field effect transistors, connected to the coils of each phase. In each pair of two switch elements, the terminal of each phase of the motor 10 is connected to the connection point between the switch elements.

[0018] The drive signal generated by the pre-drive circuit turns on and off each switch element constituting the inverter circuit, thereby supplying power to each phase of the motor 10 and rotating the rotor of the motor 10.

[0019] The motor drive circuit 101 is supplied with power from the power supply 210 provided in the host device 200. The motor drive circuit 101 is connected to the power supply 210 provided in the host device 200. The motor drive circuit 101 converts the power supplied from the power supply 210 based on the drive control signal Ctl. Then, the motor drive circuit 101 supplies the converted power to the motor 10.

[0020] [Sensor unit 102] The sensor unit 102 detects the rotational position of the rotor of the motor 10. The sensor unit 102 includes, for example, a position sensor. The sensor unit 102 includes, for example, a Hall element. The Hall element of the sensor unit 102 detects the magnetic poles of the rotor. Then, the Hall element of the sensor unit 102 outputs a Hall signal whose voltage changes according to the rotation of the rotor.

[0021] Note that the position sensor of the sensor unit 102 is not limited to a Hall element. The position sensor may be any sensor that can detect the rotational position of the rotor of the motor. For example, an encoder or the like may be applied as the position sensor. When an encoder is used as the position sensor, the sensor unit 102 may be provided outside the motor control device 100 as a device independent of the motor control device 100 rather than as one of the components of the motor control device 100.

[0022] [FG signal generation unit 103] The FG signal generation unit 103 generates an FG signal as a rotation speed signal indicating the rotation speed of the motor 10. The FG signal generation unit 103 generates a signal (FG signal) having a period (frequency) proportional to the rotation speed of the motor 10 based on, for example, a detection signal (Hall signal) output from the Hall element of the sensor unit 102. The FG signal output from the FG signal generation unit 103 is input to the host device 200. Note that the FG signal generation unit 103 may be realized by, for example, an FG pattern formed on a substrate (printed circuit board) on which the motor 10 is mounted.

[0023] [Power supply voltage measurement unit 110] The power supply voltage measurement unit 110 measures the voltage V of the power supplied from the host device 200. In other words, the power supply voltage measurement unit 110 measures the power supply voltage. The power supply voltage measurement unit 110 outputs the measured voltage value Vm to the degradation diagnosis control unit 160.

[0024] [Drive control signal generation unit 120] The drive control signal generation unit 120 generates a drive control signal Ctl for controlling the drive of the motor 10. The drive control signal generation unit 120 receives, for example, a speed command signal Sv which is a drive command signal output from the host device 200 as a drive command. When the drive control signal generation unit 120 receives the speed command signal Sv, it generates the drive control signal Ctl so that the rotation speed of the motor 10 matches the target rotation speed specified by the speed command signal Sv.

[0025] The drive control signal Ctl is, for example, a PWM (Pulse Width Modulation) signal.

[0026] The drive control signal generation unit 120 includes a speed command analysis unit 121, a duty ratio determination unit 122, and a energization control unit 123.

[0027] (Speed command analysis unit 121) The speed command analysis unit 121 receives the speed command signal Sv output from the host device 200. Then, the speed command analysis unit 121 analyzes the target rotational speed specified by the speed command signal Sv. For example, when the speed command signal Sv is a PWM signal having a duty ratio corresponding to the target rotational speed, the speed command analysis unit 121 analyzes the duty ratio of the speed command signal Sv and outputs information on the rotational speed corresponding to the duty ratio as the target rotational speed.

[0028] (Duty ratio determination unit 122) The duty ratio determination unit 122 determines the duty ratio of the PWM signal as the drive control signal Ctl based on the target rotational speed output from the speed command analysis unit 121 and the measured value of the rotational speed of the motor 10 measured by the rotational speed measurement unit 150.

[0029] Specifically, the duty ratio determination unit 122 calculates the control value of the motor 10 so that the difference between the target rotational speed and the measured value of the rotational speed of the motor 10 becomes small. Then, the duty ratio determination unit 122 determines the duty ratio of the PWM signal corresponding to the calculated control value. For example, the duty ratio determination unit 122 calculates the control value by PID (Proportional-Integral-Differential) control so that the difference between the target rotational speed and the measured value of the rotational speed of the motor 10 becomes small. Note that the duty ratio determination unit 122 may calculate the control value by either PD (Proportional-Differential) control or PI (Proportional-Integral) control. Then, the duty ratio determination unit 122 determines the duty ratio Dty of the PWM signal corresponding to the control value.

[0030] The duty ratio determination unit 122 outputs the determined duty ratio Dty to the degradation diagnosis control unit 160.

[0031] (Power supply control unit 123) The energization control unit 123 generates a PWM signal having the duty ratio determined by the duty ratio determination unit 122. Then, the energization control unit 123 outputs the generated PWM signal to the motor drive circuit 101 as a drive control signal Ctl.

[0032] [Communication unit 130] The communication unit 130 communicates with the outside. The communication unit 130 communicates with the host device 200. Specifically, the communication unit 130 transmits and receives data to and from the host device 200 as a control device. The communication unit 130 includes a transmission unit 131, a reception unit 132, and a communication control unit 133.

[0033] The transmission unit 131 transmits data to the host device 200. The reception unit 132 receives data from the host device 200. Each of the transmission unit 131 and the reception unit 132 is controlled by the communication control unit 133. The transmission unit 131 is, for example, a serial communication interface circuit that generates a predetermined serial signal and transmits it to the communication line. The reception unit 132 is, for example, a serial communication interface circuit that receives a predetermined serial signal from the communication line.

[0034] The communication control unit 133 controls each of the transmission unit 131 and the reception unit 132. The communication control unit 133 sends the encoded data to the transmission unit 131. The communication control unit 133 also decodes the data received from the reception unit 132. By the communication control unit 133 controlling the transmission unit 131 and the reception unit 132, data is transmitted and received to and from the host device 200. The communication control unit 133 is realized, for example, by program processing by a processor included in the motor control device 100.

[0035] The communication control unit 133 receives the speed command signal Sv output as a drive command from the host device 200. Then, the communication control unit 133 transmits the received speed command signal Sv to the speed command analysis unit 121.

[0036] [Current measurement unit 140] The current measurement unit 140 measures the current of the power supplied from the motor drive circuit 101 to the motor 10. The current measurement unit 140 includes, for example, a current transformer. The current measurement unit 140 outputs the measured current value Im of the current of the power supplied from the motor drive circuit 101 to the motor 10 to the degradation diagnosis control unit 160. The current measurement unit 140 acquires the current value Im, which is an example of a characteristic value related to the motor, for each sampling period and outputs it to the degradation diagnosis control unit 160.

[0037] [Rotation speed measurement unit 150] The rotation speed measurement unit 150 measures the rotation speed of the motor 10. The rotation speed measurement unit 150 measures the rotation speed of the motor 10 based on, for example, the detection signal (Hall signal) of the Hall element in the sensor unit 102. The rotation speed measurement unit 150 outputs the measured rotation speed Rm to the degradation diagnosis control unit 160.

[0038] [Degradation diagnosis control unit 160] The degradation diagnosis control unit 160 detects an abnormality of the motor 10. The degradation diagnosis control unit 160 diagnoses the degradation of the motor 10 based on any one of the voltage value Vm, the current value Im, the rotation speed Rm of the motor 10, and the duty ratio Dty.

[0039] [Data management unit 170] The data management unit 170 manages data.

[0040] [Upper device 200] Next, the upper device 200 will be described. The upper device 200 supplies power to the motor control device 100. In addition, the upper device 200 instructs the motor control device 100 of the rotation speed. The upper device 200 includes a power supply 210, a data processing control unit 220, and a communication unit 230.

[0041] [Power supply 210] The power supply 210 supplies power for operating the motor 10 to the motor control device 100. The power supply 210 is a DC power supply. The power supply 210 supplies, for example, 12V (volts) of power to the motor control device 100.

[0042] [Data processing control unit 220] The data processing control unit 220 instructs the motor control device 100 of the target rotational speed (target rotational speed) of the motor 10. The data processing control unit 220 transmits a speed command signal Sv to the motor control device 100 via the communication unit 230. By transmitting the speed command signal Sv to the motor control device 100, the data processing control unit 220 instructs the motor control device 100 of the target rotational speed (target rotational speed).

[0043] [Communication unit 230] The communication unit 230 communicates with the motor control device 100. The communication unit 230 communicates with the communication unit 130 in the motor control device 100. The communication unit 230 receives the signal transmitted from the transmission unit 131 in the communication unit 130 as a received signal Rx. Also, the communication unit 230 transmits a transmission signal Tx to the reception unit 132 in the communication unit 130. The communication unit 230 is, for example, a serial communication interface circuit that generates a predetermined serial signal and transmits and receives the serial signal from the communication line.

[0044] [Processing in the deterioration diagnosis control unit] Next, the processing performed by the deterioration diagnosis control unit 160 will be described. By describing the processing performed by the deterioration diagnosis control unit 160, the steps included in the motor deterioration diagnosis method for diagnosing the deterioration of the motor 10 performed by the motor control device 100 will be described. Also, the procedure of the program executed by the computer included in the motor control device 100 will be described. FIG. 2 is a flowchart for explaining the processing in the motor control device 100 which is an example of the motor control device according to the present embodiment.

[0045] The inventors have found that in order to diagnose the deterioration of the motor 10, regarding the characteristic values related to the motor 10, during operation, the coefficient of variation of the characteristic values is calculated, and the difference between the coefficient of variation and the average of the coefficient of variation is calculated, whereby the deterioration state can be diagnosed.

[0046] In the motor control device 100, the deterioration diagnosis control unit 160 executes an inspection data acquisition step (step S10), a statistic calculation step (step S20), and a coefficient of variation calculation step (step S30). Further, the deterioration diagnosis control unit 160 subsequently executes a coefficient of variation average calculation step (step S40), a coefficient of variation absolute deviation calculation step (step S50), and a diagnosis step (step S60). Note that the deterioration diagnosis control unit 160 repeatedly executes steps S10 to S60 while the motor 10 is operating.

[0047] (Step S10) When the motor 10 is operating, the deterioration diagnosis control unit 160 acquires, as inspection data, characteristic values of the sampled motor 10 (inspection data acquisition step). Examples of the characteristic values of the motor 10 include any one of the current value, voltage value, rotation speed, and duty ratio of the power supplied to the motor 10.

[0048] Here, the inspection data acquired by the deterioration diagnosis control unit 160 for the nth time is denoted as inspection data xi(n). However, n is an integer of 1 or more.

[0049] (Step S20) Next, the deterioration diagnosis control unit 160 calculates a statistic using the acquired inspection data (statistic calculation step). The deterioration diagnosis control unit 160 calculates the standard deviation of the inspection data as an example of the statistic. To calculate the standard deviation, the deterioration diagnosis control unit 160 calculates the average value of the inspection data and the average value of the squared values of the inspection data (square average value).

[0050] A specific calculation method will be described. The deterioration diagnosis control unit 160 updates and calculates the nth average value Xa(n) using the nth inspection data xi(n) and the (n - 1)th average value Xa(n - 1) based on Equation 1. However, N is an integer of 2 or more. N is, for example, any integer from 100 to 1000.

[0051]

Equation

[0052] Further, the deterioration diagnosis control unit 160 calculates the n-th mean square value Xsa(n) using the n-th inspection data xi(n) and the (n-1)-th mean square value Xsa(n-1) based on Equation 2.

[0053]

Number

[0054] Note that the mean square value Xsa(n) corresponds to the average value of the squared values of the inspection data xi, as shown in Equation 3.

[0055]

Number

[0056] Then, the deterioration diagnosis control unit 160 calculates the n-th standard deviation σi(n) using the n-th average value Xa(n) and the n-th mean square value Xsa(n) based on Equation 4.

[0057]

Number

[0058] When calculating the standard deviation, if the standard deviation is calculated using the variance for a plurality of data, it is necessary to temporarily store the data used for the calculation. As the amount of data increases, the area for storing the data increases and the memory consumption increases.

[0059] Therefore, the deterioration diagnosis control unit 160 calculates the average value and the mean square value using the recurrence formulas (exponential moving average) shown in Equation 1 and Equation 2 to obtain the standard deviation. By using the recurrence formula (exponential moving average), the standard deviation can be calculated by sequential calculation, so that the memory consumption can be reduced.

[0060] (Step S30) Next, the deterioration diagnosis control unit 160 calculates the coefficient of variation CV based on the statistic calculated in step S20 (coefficient of variation calculation step). Specifically, the deterioration diagnosis control unit 160 calculates the n-th coefficient of variation CV(n) based on Equation 5 using the n-th average value Xa(n) and the standard deviation σi(n).

[0061]

Number

[0062] (Step S40) Next, the deterioration diagnosis control unit 160 calculates the average value of the coefficient of variation using the coefficient of variation CV(n) calculated in step S30 (average coefficient of variation calculation step).

[0063] The deterioration diagnosis control unit 160 calculates the average coefficient of variation value CVave(n), which is the average value of the coefficient of variation CV, based on Equation 6 using the coefficient of variation CV(n) calculated in step S30.

[0064]

Number

[0065] (Step S50) Next, the deterioration diagnosis control unit 160 calculates the absolute deviation of the coefficient of variation AD(n), which is the absolute deviation of the coefficient of variation CV, based on the coefficient of variation CV(n) and the average coefficient of variation value CVave(n) that is the average value of the coefficient of variation CV (absolute deviation of coefficient of variation calculation step).

[0066]

Number

[0067] Furthermore, the deterioration diagnosis control unit 160 smoothes the coefficient of variation absolute deviation AD(n) to calculate a smoothed coefficient of variation absolute deviation ADs(n). The smoothing is calculated by a recurrence formula (exponential moving average), for example, as shown in Equation 1 and Equation 2. The deterioration diagnosis control unit 160 updates the smoothed coefficient of variation absolute deviation ADs(n) to a value obtained by dividing the sum of the coefficient of variation absolute deviation AD(n) and the value obtained by multiplying the smoothed coefficient of variation absolute deviation ADs(n−1) by a smoothing coefficient Ns by a value obtained by adding 1 to the smoothing coefficient Ns. Specifically, the deterioration diagnosis control unit 160 calculates the coefficient of variation absolute deviation ADs(n) based on Equation 8.

[0068] [Number]

[0069] The smoothing coefficient Ns is desirably set to a value equivalent to 24 hours or more, for example. For example, when the sampling period is 50 milliseconds, the smoothing coefficient Ns is desirably set to 172,800 or more. Also, for example, when the sampling period is 1 second, the smoothing coefficient Ns is desirably set to 86,400 or more.

[0070] (Step S60) Next, the deterioration diagnosis control unit 160 diagnoses the deterioration of the motor 10 based on the smoothed coefficient of variation absolute deviation ADs(n) (diagnosis step). The deterioration diagnosis control unit 160 determines the deterioration of the motor 10 based on the smoothed coefficient of variation absolute deviation ADs(n). The deterioration diagnosis control unit 160 determines that it is normal (less deterioration), for example, when the smoothed coefficient of variation absolute deviation ADs(n) is smaller than a first threshold value. Also, the deterioration diagnosis control unit 160 determines that abnormal noise may occur, for example, when the smoothed coefficient of variation absolute deviation ADs(n) is larger than the first threshold value and smaller than a second threshold value larger than the first threshold value. Furthermore, the deterioration diagnosis control unit 160 determines that it is on the verge of failure, for example, when the smoothed coefficient of variation absolute deviation ADs(n) is larger than the second threshold value.

[0071] (Step S70) The deterioration diagnosis control unit 160 determines whether to end the process. If it is determined to end the process (YES in step S70), the deterioration diagnosis control unit 160 ends the process. If the process is not ended, in other words, if the process is to be continued (NO in step S70), the deterioration diagnosis control unit 160 returns to step S10 and repeats the process.

[0072] <Operating results of the motor control device> Next, the operating results when operating a motor control device 100, which is an example of the motor control device according to the present embodiment, will be described. Each of FIGS. 3, 4, and 5 is a diagram for explaining the operating results of a motor control device 100, which is an example of the motor control device according to the present embodiment. Note that, in the operating results shown in each of FIGS. 3, 4, and 5, the current value of the power supplied to the motor 10 is used as a characteristic value regarding the motor 10.

[0073] FIGS. 3 and 4 show different samples. In each of FIGS. 3 and 4, the time (unit: hour) when the data was acquired, the measured current value and the average value (broken line) (unit: arbitrary unit), the coefficient of variation absolute deviation (unit: arbitrary unit), and the smoothed coefficient of variation absolute deviation (unit: arbitrary unit) are shown in a table. FIG. 5 is a graph with the horizontal axis representing time and the vertical axis representing the smoothed coefficient of variation absolute deviation for the sample of FIG. 4.

[0074] As shown in FIGS. 3, 4, and 5, it can be seen that in the motor control device 100, as time passes, the motor 10 deteriorates and the smoothed coefficient of variation absolute deviation increases. Therefore, according to the motor control device according to the present embodiment, the deterioration of the motor can be diagnosed by using the smoothed coefficient of variation absolute deviation.

[0075] As shown in FIG. 6 as the state diagnosis (spectrum), the deterioration diagnosis control unit 160 may, for example, normalize the smoothed absolute deviation of the coefficient of variation to a value from 0% to 100% and perform diagnosis based on the normalized value. For example, when the normalized absolute deviation of the coefficient of variation is less than 45%, the deterioration diagnosis control unit 160 may determine that it is normal. Also, for example, when the normalized absolute deviation of the coefficient of variation is 45% or more and less than 70%, the deterioration diagnosis control unit 160 may determine that the andelon value is greater than 2. Further, for example, when the normalized absolute deviation of the coefficient of variation is 70% or more and less than 90%, the deterioration diagnosis control unit 160 may determine that the andelon value is greater than 10 and determine that there is a possibility that abnormal noise occurs. Furthermore, for example, when the normalized absolute deviation of the coefficient of variation is 90% or more, the deterioration diagnosis control unit 160 may determine that it is on the verge of failure.

[0076] <Summary> According to the motor control device according to the present embodiment, the deterioration state of the motor can be diagnosed.

[0077] Note that, for example, when using the current value as a characteristic value, the current measurement unit 140 is an example of an acquisition unit that acquires characteristic values related to the motor. Also, the deterioration diagnosis control unit 160 is an example of a processing unit that processes the characteristic values acquired by the acquisition unit.

[0078] While showing an example of the operation of the motor control device according to the present embodiment, the effects of the motor control device according to the present embodiment will be described. In the motor control device, when using the value of the effective current value acquired at regular time intervals, abnormalities in the data can be detected. By detecting abnormalities in the data, abnormalities in the motor can be detected. On the other hand, it is difficult to accurately determine the deterioration state of the motor by detecting abnormalities in the data.

[0079] The deterioration and lifespan of a motor are mainly caused by bearings. As the operating time of the motor increases, the wear and deterioration of the bearings progress. During the process of bearing wear and deterioration, local flaking and seizure occur. The resistance caused by flaking and seizure is reflected in the current value. However, if the resistance is removed during subsequent operation even if resistance occurs due to flaking, seizure, etc., the data will indicate normalcy.

[0080] Here, an explanation will be given while showing the current value when the motor control device according to this embodiment is operated. Each of FIGS. 7 and 8 is a diagram for explaining the operation result of a motor control device 100 which is an example of the motor control device according to this embodiment. In FIGS. 7 and 8, the samples of the motor 10 are different.

[0081] For example, FIG. 7 is a diagram showing a period Pa indicating an abnormal location where the current shows a value larger than the average (outlier value), and a period Pn showing a normal value after the period Pa.

[0082] In an algorithm where the magnitude of the outlier value is reflected in the abnormality score, for example, an algorithm using the coefficient of variation as the abnormality score, a very large abnormality score is shown during the period Pa. However, just because a large abnormality score is shown, it cannot be determined that the bearing condition has deteriorated considerably and the lifespan is near. For example, in the case of the sample shown in FIG. 7, the andelon value of the bearing is about 8.

[0083] On the other hand, the sample shown in FIG. 8 shows almost no large outlier value. However, the andelon value is close to 50.

[0084] That is, although the outlier value is a phenomenon that occurs during the deterioration process of the bearing, it does not indicate what percentage of the deterioration state it is when the failure state is set to 100%. Therefore, when it is desired to accurately diagnose the deterioration state with respect to a failure, using the index for anomaly detection as the index for deterioration diagnosis will rather hinder the diagnosis.

[0085] The bearings in a motor deteriorate over the operating time. In particular, the bearing deterioration accelerates after the grease decreases or deteriorates. Therefore, when it is desired to diagnose the deterioration state of the motor, as in the image diagram shown in Fig. 9, it is desirable to find in the data a variable whose value gradually increases with deterioration by the end of the life Te and use it as an index.

[0086] As shown in Fig. 5, the inventors found that the absolute deviation of the coefficient of variation is a variable whose value gradually increases with deterioration as in the image diagram shown in Fig. 9.

[0087] For example, the results using the average value, standard deviation, skewness, and kurtosis of current data are shown in Figs. 10 to 13. Each of Figs. 10 to 13 is a diagram for explaining an example of a variable for diagnosing the state of the motor control device. Fig. 10 is a diagram showing the average value (mean) of current data. Fig. 11 is a diagram showing the standard deviation of current data. Fig. 12 is a diagram showing the skewness of current data. Fig. 13 is a diagram showing the kurtosis of current data.

[0088] As shown in each of Figs. 10 to 13, in actual use, no matter which statistic of the average value, standard deviation, skewness, and kurtosis of current data is used, it is greatly affected by disturbances and the tendency as in the image diagram shown in Fig. 9 cannot be obtained.

[0089] Also, for example, a method of directly monitoring the vibration level of the bearing using a vibration sensor for state diagnosis can be considered. However, attaching a vibration sensor to the motor is not desirable in terms of cost. It is desirable to be able to perform state diagnosis by utilizing only data such as the current of the motor control device.

[0090] According to the motor control device according to the present embodiment, the deterioration state of the motor can be diagnosed using inspection data indicating characteristics of the motor such as current data. Also, according to the motor control device according to the present embodiment, the deterioration state of the motor can be diagnosed while suppressing the calculation cost.

Explanation of Signs

[0091] 1 Motor system 10 Motor 20 Motor drive control system 100 Motor control device 110 Power supply voltage measurement unit 120 Drive control signal generation unit 130 Communication unit 140 Current measurement unit 150 Rotational speed measurement unit 160 Deterioration diagnosis control unit 170 Data management unit 200 Host device

Claims

1. A deterioration diagnosis device for diagnosing deterioration of a motor, comprising: an acquisition unit that acquires characteristic values related to the motor for each sampling period; a processing unit that processes the characteristic values acquired by the acquisition unit, wherein the processing unit performs: (a) a procedure of acquiring characteristic values related to the motor as inspection data; (b) a procedure of updating the coefficient of variation of the inspection data; (c) a procedure of updating the average value of the coefficient of variation; and (d) a procedure of updating the absolute deviation of the difference between the coefficient of variation and the average value of the coefficient of variation. Deterioration diagnosis device.

2. The processing unit after the step (d), further performs: (e) a procedure of smoothing the absolute deviation; and (f) a procedure of determining deterioration of the motor based on the smoothed absolute deviation. The deterioration diagnosis device according to claim 1.

3. The characteristic value is a current value of the electric power supplied to the motor. The deterioration diagnosis device according to any one of claims 1 or 2.

4. In the step (e), the smoothed absolute deviation is updated to a value obtained by dividing the sum of the absolute deviation and the value obtained by multiplying the smoothed absolute deviation by a smoothing coefficient by a value obtained by adding 1 to the smoothing coefficient. The deterioration diagnosis device according to claim 2.

5. The smoothing coefficient is 86,400 or more. The deterioration diagnosis device according to claim 4.

6. A motor and a deterioration diagnosis device for diagnosing deterioration of the motor, wherein the deterioration diagnosis device comprises: an acquisition unit that acquires characteristic values related to the motor for each sampling period; a processing unit that processes the characteristic values acquired by the acquisition unit, and the processing unit performs: a) a procedure of acquiring characteristic values related to the motor as inspection data; b) a procedure of updating the coefficient of variation of the inspection data; c) a procedure of updating the average value of the coefficient of variation; and d) a procedure of updating the absolute deviation of the difference between the coefficient of variation and the average value of the coefficient of variation. Motor system.

7. A deterioration diagnosis method for diagnosing deterioration of a motor, comprising: a) a step of acquiring characteristic values related to the motor as inspection data; b) a step of updating the coefficient of variation of the inspection data; c) a step of updating the average value of the coefficient of variation; and d) a step of updating the absolute deviation of the difference between the coefficient of variation and the average value of the coefficient of variation. Deterioration diagnosis method. ​

Images