Abnormality detection device, motor system, and abnormality detection method

Abstract

To provide an abnormality detection device suppressing erroneous detection in an abnormality determination of a motor.SOLUTION: An abnormality detection device detecting an abnormality of a motor has an acquisition part acquiring a characteristic value with respect to the motor per sampling period, and a processing part processing the characteristic value acquired by the acquisition part. The processing part executes steps of (a) acquiring the characteristic value with respect to the motor as inspection data, (b) updating an average value of the inspection data, (c) updating a standard deviation of the inspection data, (d) updating an abnormality degree by dividing squares of a difference between the inspection data and the average value by squares of the standard deviation, and (e) calculating a cumulative sum of the abnormality degree based on a threshold value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an abnormality detection device, a motor system, and an abnormality detection method.

Background Art

[0002] Patent Document 1 discloses an abnormality determination device that determines a mechanical abnormality of a motor drive mechanism. Patent Document 1 discloses that the abnormality determination device includes a data abnormality determination unit that determines a data abnormality of time-series data, and a mechanical abnormality determination unit that determines a mechanical abnormality of the motor drive mechanism based on the acquisition mode of the time-series data determined to have a data abnormality.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an abnormality detection algorithm, there may be a case where it is assumed that the data follows a normal distribution. When it is assumed that the data follows a normal distribution, if the data deviates from the normal distribution, an abnormality may be misdetected.

[0005] The present disclosure provides an abnormality detection device that suppresses misdetection in the abnormality determination of a motor.

Means for Solving the Problems

[0006] In one aspect of the present disclosure, there is provided an abnormality detection device for detecting an abnormality of a motor, the device comprising: an acquisition unit that acquires characteristic values related to the motor for 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 of acquiring characteristic values related to the motor as inspection data; (b) a procedure of updating an average value of the inspection data; (c) a procedure of updating a standard deviation of the inspection data; (d) a procedure of updating an abnormality degree by dividing a square of a difference between the inspection data and the average value by a square of the standard deviation; and (e) a procedure of calculating a cumulative sum of the abnormality degrees based on a threshold value.

Advantages of the Invention

[0007] According to the motor abnormality detection device of the present disclosure, false detection in motor abnormality determination can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out 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 an abnormality detection device that detects an abnormality 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, an abnormality detection 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 abnormality detection 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 circuits are 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 the program stored in the memory to realize the processing.

[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 the 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 abnormality detection 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 abnormality detection 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 abnormality detection 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 abnormality detection 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 abnormality detection control unit 160.

[0038] [Abnormality detection control unit 160] The abnormality detection control unit 160 detects an abnormality of the motor 10. The abnormality detection control unit 160 estimates and detects the occurrence of an abnormality 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 abnormality detection control unit> Next, the processing performed by the abnormality detection control unit 160 will be described. By describing the processing performed by the abnormality detection control unit 160, the steps included in the motor abnormality detection method for detecting the abnormality 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 by calculating the Z-score for the characteristic values related to the motor 10 and calculating the cumulative sum of the Z-scores, false detection can be suppressed in detecting the abnormality of the motor 10.

[0046] The abnormality detection control unit 160 in the motor control device 100 executes an inspection data acquisition step (step S10), a statistic calculation step (step S20), and a Z-score calculation step (step S30). Subsequently, the abnormality detection control unit 160 continuously executes an abnormality degree calculation step (step S40), an abnormality determination value calculation step (step S50), and an abnormality determination step (step S60). Note that the abnormality detection control unit 160 repeatedly executes steps S10 to S60 when the motor 10 is operating.

[0047] (Step S10) When the motor 10 is operating, the abnormality detection control unit 160 acquires, as inspection data, the 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, let the inspection data acquired by the abnormality detection control unit 160 for the nth time be inspection data xi(n). However, n is an integer of 1 or more.

[0049] (Step S20) Next, the abnormality detection control unit 160 calculates a statistic using the acquired inspection data (statistic calculation step). As an example of the statistic, the abnormality detection control unit 160 calculates the standard deviation of the inspection data. To calculate the standard deviation, the abnormality detection 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 abnormality detection control unit 160 updates and calculates the nth average value Xa(n) based on Equation 1 using the nth inspection data xi(n) and the (n - 1)th average value Xa(n - 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 abnormality detection 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]

Equation

[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]

Equation

[0056] Then, the abnormality detection 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]

Equation

[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 becomes larger, and the memory consumption increases.

[0059] Therefore, the abnormality detection control unit 160 calculates the average value and the mean square value and obtains the standard deviation by using the recurrence formulas (exponential moving average) shown in Equation 1 and Equation 2. By using the recurrence formulas (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 abnormality detection control unit 160 calculates a Z-score Zs based on the statistic calculated in step S20 (Z-score calculation step). Specifically, the abnormality detection control unit 160 calculates the nth Z-score Zs(n) based on Equation 5 using the nth average value Xa(n) and standard deviation σi(n).

[0061]

Number

[0062] Note that the Z-score for the inspection data xi is a value obtained by converting the inspection data xi so that the average value is 0 and the standard deviation is 1.

[0063] (Step S40) Next, the abnormality detection control unit 160 calculates the degree of abnormality using the Z-score Zs(n) calculated in step S30 (degree of abnormality calculation step).

[0064] The abnormality detection control unit 160 calculates the degree of abnormality Xt(n) based on Equation 6 using the Z-score Zs(n) calculated in step S30. That is, the abnormality detection control unit 160 updates the degree of abnormality Xt(n) by dividing the square of the difference between the inspection data xi(n) and the average value Xa(n) by the square of the standard deviation σi(n).

[0065]

Number

[0066] (Step S50) Next, the abnormality detection control unit 160 calculates an abnormality determination value based on the degree of abnormality Xt(n) (abnormality determination value calculation step). The abnormality detection control unit 160 calculates the nth abnormality determination value Sd(n) based on the (n - 1)th abnormality determination value Sd(n - 1) and the degree of abnormality Xt(n). The abnormality detection control unit 160 updates the abnormality determination value Sd(n) based on Equation 7. That is, the abnormality detection control unit 160 calculates the abnormality determination value Sd(n), which is the cumulative sum of the degree of abnormality Xt(n), based on the threshold th.

[0067] When the abnormality degree Xt(n) is greater than or equal to a threshold value (threshold value th or more), the abnormality detection control unit 160 updates the abnormality determination value Sd(n), which is the cumulative sum of the abnormality degree Xt(n), to a value obtained by adding the abnormality degree Xt(n) as the abnormality determination value Sd(n). Further, when the abnormality degree Xt(n) is less than the threshold value (less than the threshold value th), the abnormality detection control unit 160 updates the abnormality determination value Sd(n) to a value obtained by subtracting the abnormality degree Xt(n) from the abnormality determination value Sd(n), which is the cumulative sum of the abnormality degree Xt(n).

[0068] Note that the abnormality detection control unit 160 calculates the threshold value th based on the significance level and the chi-square distribution.

[0069]

Equation

[0070] (Step S60) Next, the abnormality detection control unit 160 detects an abnormality of the motor 10 based on the abnormality determination value Sd(n) (abnormality detection step). When the abnormality determination value Sd(n) is greater than a predetermined threshold value, the abnormality detection control unit 160 detects that an abnormality has occurred in the motor 10.

[0071] (Step S70) The abnormality detection control unit 160 determines whether to end the process. When ending the process (YES in Step S70), the abnormality detection control unit 160 ends the process. When not ending the process, in other words, when continuing the process (NO in Step S70), the abnormality detection control unit 160 returns to Step S10 and repeats the process.

[0072] <Operation Result of Motor Control Device> Next, the operation results when operating the motor control device 100, which is an example of the motor control device according to this embodiment, will be described. FIGS. 3 and 4 are diagrams for explaining the degree of abnormality in the motor control device 100, which is an example of the motor control device according to this embodiment. Note that the degree of abnormality shown in FIGS. 3 and 4 is calculated using the current value of the power supplied to the motor 10 as a characteristic value related to the motor 10.

[0073] FIG. 3 is a diagram showing the degree of abnormality calculated in the motor control device 100. The horizontal axis in FIG. 3 is the time elapsed from a predetermined time, and the vertical axis is the degree of abnormality. Note that the unit of time is hours (h), and the unit of the degree of abnormality is an arbitrary unit. FIG. 4 is a diagram showing the frequency distribution of the degree of abnormality shown in FIG. 3. The horizontal axis in FIG. 4 is the abnormality distribution, and the vertical axis is the frequency. Note that the unit of the abnormality distribution is an arbitrary unit.

[0074] It is known that the value obtained by squaring the Z-score obtained by standardizing the data distributed in a normal distribution follows a chi-square distribution with 1 degree of freedom. The degree of abnormality Xt(n), which is the square of the Z-score Zs(n) calculated in the motor control device 100, approximately follows a chi-square distribution as shown in FIG. 4.

[0075] For example, in the chi-square distribution, the value at a significance level of 5% is 3.84, and the value at a significance level of 1% is 6.63. Therefore, in the motor control device 100, for example, when the significance level is set to 1% and the threshold th is set to 6.63, since the values larger than the threshold th are probabilistically rare (1% or less), if the values larger than the threshold th are continuous, there is a high possibility of abnormality. Therefore, the motor control device 100 calculates the cumulative sum of the values larger than the threshold th as the abnormality determination value.

[0076] Explaining with FIG. 3 as an example, the motor control device 100 performs a cumulative sum of the degree of abnormality larger than the threshold th with the degree of abnormality as the original value. And the motor control device 100 performs a cumulative sum of the degree of abnormality less than or equal to the threshold th with the value obtained by making the degree of abnormality negative.

[0077] Furthermore, the results when the motor control device 100 is operated over a long period of time will be described. FIGS. 5 and 6 are diagrams for explaining the operation results of the motor control device 100 which is an example of the motor control device according to the present embodiment. In the operation results shown in FIGS. 5 and 6, as the characteristic value regarding the motor 10, the current value of the power supplied to the motor 10 is used.

[0078] In each of FIGS. 5 and 6, the time (unit: hour) when the data was acquired, the current measurement value and the average value (broken line) (unit: arbitrary unit), and the abnormality determination value (unit: arbitrary unit) are shown in a table. As shown in FIGS. 5 and 6, as time passes, the abnormality determination value increases, and it can be seen that the abnormality determination is approximately correctly performed.

[0079] As described above, by calculating the abnormality determination value, the motor control device 100 executes a cumulative sum based on the chi-square distribution. By the motor control device 100 executing a cumulative sum based on the chi-square distribution, even if the distribution of the characteristic value deviates from the normal distribution, the deviation in accuracy can be suppressed and false detection of an abnormality can be suppressed.

[0080] <Summary> According to the motor control device according to the present embodiment, false detection in the abnormality determination of the motor can be suppressed.

[0081] For example, when the current value is used as the characteristic value, the current measurement unit 140 is an example of an acquisition unit that acquires the characteristic value regarding the motor. Also, the abnormality detection control unit 160 is an example of a processing unit that processes the characteristic value acquired by the acquisition unit.

[0082] The variation of characteristic values in the motor control device according to this embodiment will be described. Each of FIGS. 7 and 8 is a diagram for explaining the variation of characteristic values in the motor control device according to this embodiment. In FIG. 7, the time (unit: hour) when data was acquired, the current measurement value and the average value (broken line) (unit: arbitrary unit), the histogram and the skewness (unit: arbitrary unit) are shown in a table. FIG. 8 shows that the vertical axis represents the ratio (unit: %), and the horizontal axis represents the time (unit: hour). FIG. 8 shows the ratio of data below -3σ, above +3σ, below -3σ and above +3σ.

[0083] As shown in FIG. 8, disturbances occur at arrow A and arrow B. That is, disturbances occur between time 230 and time 774 and between time 774 and time 1537 in FIG. 7 respectively.

[0084] As shown in FIGS. 7 and 8, when a disturbance occurs, the skewness is reversed. When the skewness is reversed by the disturbance, the histogram of the current measurement value deviates from the normal distribution. When the skewness is reversed by the disturbance, the characteristic values of the motor may deviate from the normal distribution. That is, the reversal of the skewness due to the disturbance is a factor in the deviation of the accuracy of the anomaly detection algorithm when it is assumed that the data follows a normal distribution.

[0085] According to the motor control device according to this embodiment, by using the cumulative sum based on the chi-square distribution, even if the characteristic values of the motor deviate from the normal distribution, the deviation of the accuracy can be eliminated.

[0086] As described above, the motor control device has been described according to the embodiment, but the present invention is not limited to the above embodiment. Various modifications and improvements such as combinations or replacements with some or all of other embodiments are possible within the scope of the present invention.

Explanation of Signs

[0087] 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 Rotation speed measurement unit 160 Abnormality detection control unit 170 Data management unit 200 Higher-level device

Claims

1. An abnormality detection device for detecting an abnormality 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 an average value of the inspection data; (c) a procedure of updating a standard deviation of the inspection data; (d) a procedure of updating an abnormality degree by dividing a square of a difference between the inspection data and the average value by a square of the standard deviation; (e) a procedure of calculating a cumulative sum of the abnormality degree based on a threshold value; and is an abnormality detection device.

2. The characteristic value is any one of a current value of electric power supplied to the motor, a voltage value, a rotation speed of the motor, and a duty ratio, The abnormality detection device according to claim 1.

3. In the procedure (e), when the abnormality degree is greater than or equal to the threshold value, a value obtained by adding the abnormality degree to the cumulative sum of the abnormality degree is updated as the cumulative sum of the abnormality degree; when the abnormality degree is less than the threshold value, a value obtained by subtracting the abnormality degree from the cumulative sum of the abnormality degree is updated as the cumulative sum of the abnormality degree, The abnormality detection device according to any one of claim 1 or claim 2.

4. In the procedure (e), the threshold value is calculated based on a significance level and a chi-square distribution, The abnormality detection device according to claim 3.

5. a motor; an abnormality detection device for detecting an abnormality of the motor; and the abnormality detection 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, wherein the processing unit performs: (a) a procedure of acquiring characteristic values related to the motor as inspection data; (b) a procedure of updating an average value of the inspection data; (c) a procedure of updating a standard deviation of the inspection data; (d) a procedure of updating an abnormality degree by dividing a square of a difference between the inspection data and the average value by a square of the standard deviation; (e) a procedure of calculating a cumulative sum of the abnormality degree based on a threshold value; and is a motor system.

6. An abnormality detection method for detecting an abnormality of a motor, comprising: (a) a step of acquiring characteristic values related to the motor as inspection data; (b) a step of updating an average value of the inspection data; (c) a step of updating a standard deviation of the inspection data; (d) a step of updating an abnormality degree by dividing a square of a difference between the inspection data and the average value by a square of the standard deviation; (e) A step of calculating a cumulative sum of the abnormality degree based on a threshold value; including: An abnormality detection method.

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