JP7541307B2 - Diagnostic device, diagnostic system, baseboard, diagnostic method and program - Google Patents

Description

The present invention relates to a diagnostic device, a diagnostic system, a baseboard, a diagnostic method, and a program.

Conventionally, a technique is known in which an AC voltage is applied to an electric circuit, the impedance is measured, and the deterioration state of the electric circuit is diagnosed based on the measured impedance.

For example, Patent Document 1 discloses a technique for applying an AC voltage to a capacitor, measuring the impedance, and determining the deterioration of the capacitor based on the measured impedance.

JP 2006-47283 A

However, the technology described in Patent Document 1 limits the target of degradation diagnosis to a specific circuit element, the capacitor, and is not highly versatile. In addition, the technology described in Patent Document 1 is premised on measuring the impedance when the capacitor is not in use, and is not capable of accurately diagnosing the degradation state of a capacitor being used in an operating circuit.

Therefore, there was room for improvement in technology for diagnosing the deterioration state of electrical equipment.

In light of these circumstances, the objective of the present invention is to improve technology for diagnosing the deterioration state of electrical equipment.

A diagnostic device according to an embodiment of the present invention comprises:
A diagnostic device for diagnosing a deterioration state of an electrical device, comprising:
an AC voltage application unit capable of applying an AC voltage or passing an AC current to a power supply line connected to a circuit module included in the electrical device;
an impedance calculation means for calculating an impedance of the circuit module based on a voltage and a current of the power supply line to which an AC voltage is applied by the AC voltage application unit while the electrical device is in operation;
a determination means for determining a deterioration state of the circuit module based on the calculated impedance,
The AC voltage application unit applies an AC voltage having an amplitude determined according to the electrical device to the power supply line.

A diagnostic system according to an embodiment of the present invention comprises:
A diagnostic system for diagnosing a deterioration state of an electrical device, comprising:
an AC voltage application unit capable of applying an AC voltage or passing an AC current to a power supply line connected to a circuit module included in the electrical device;
an impedance calculation means for calculating an impedance of the circuit module based on a voltage and a current of the power supply line to which an AC voltage is applied by the AC voltage application unit while the electrical device is in operation;
a determination means for determining a deterioration state of the circuit module based on the calculated impedance,
The AC voltage application unit applies an AC voltage having an amplitude determined according to the electrical device to the power supply line.

A diagnostic device according to an embodiment of the present invention comprises:
A diagnostic system for diagnosing a deterioration state of an electrical device, comprising: an AC voltage application unit capable of applying an AC voltage or passing an AC current to a power supply line connected to a circuit module included in the electrical device; impedance calculation means for calculating an impedance of the circuit module based on the voltage and current of the power supply line to which an AC voltage is applied by the AC voltage application unit while the electrical device is in operation; and determination means for determining a deterioration state of the circuit module based on the calculated impedance, wherein the AC voltage application unit applies an AC voltage of an amplitude determined according to the electrical device to the power supply line,
The power supply device includes at least one of the AC voltage application unit, the impedance calculation unit, and the determination unit.

The base board according to one embodiment of the present invention includes:
A diagnostic system for diagnosing a deterioration state of an electrical device, comprising: an AC voltage application unit capable of applying an AC voltage or passing an AC current to a power supply line connected to a circuit module included in the electrical device; impedance calculation means for calculating an impedance of the circuit module based on the voltage and current of the power supply line to which an AC voltage is applied by the AC voltage application unit while the electrical device is in operation; and determination means for determining a deterioration state of the circuit module based on the calculated impedance, wherein the AC voltage application unit applies an AC voltage of an amplitude determined according to the electrical device to the power supply line,
The power supply device includes at least one of the AC voltage application unit, the impedance calculation unit, and the determination unit.

A diagnostic method according to one embodiment of the present invention comprises:
A diagnostic method for diagnosing a deterioration state of an electrical device, comprising:
applying an AC voltage or passing an AC current through a power supply line connected to a circuit module included in the electrical device;
calculating an impedance of the circuit module based on a voltage and a current of the power supply line to which an AC voltage is applied while the electrical device is in operation;
determining a deterioration state of the circuit module based on the calculated impedance;
The amplitude of the AC voltage applied to the power supply line is determined according to the electrical device.

A program according to an embodiment of the present invention includes:
A diagnostic device for diagnosing a deterioration state of an electrical device, the diagnostic device including an AC voltage application unit capable of applying an AC voltage or flowing an AC current to a power supply line connected to a circuit module included in the electrical device,
an impedance calculation means for calculating an impedance of the circuit module based on a voltage and a current of the power supply line to which an AC voltage is applied by the AC voltage application unit while the electrical device is in operation;
a determining unit that determines a deterioration state of the circuit module based on the calculated impedance,
The AC voltage application unit applies an AC voltage having an amplitude determined according to the electrical device to the power supply line.

According to one embodiment of the present invention, technology for diagnosing the deterioration state of electrical equipment is improved.

1 is a diagram showing a schematic configuration of a diagnostic system according to an embodiment of the present invention; 1 is a diagram showing a state in which a diagnostic device according to an embodiment of the present invention is incorporated into an electrical device. 1 is a block diagram showing a schematic configuration of a diagnostic device according to an embodiment of the present invention; FIG. 2 is a block diagram showing a schematic configuration of the terminal device shown in FIG. 1 . FIG. 2 is a diagram showing a state in which an AC voltage is applied to a circuit module. 5A and 5B are diagrams illustrating examples of voltage signals and current signals when impedance is calculated. FIG. 1 is a diagram illustrating an example of a Nyquist diagram. FIG. 2 is a diagram illustrating an example of an equivalent circuit of a circuit module. 4 is a flowchart showing the operation of the diagnostic device according to the embodiment of the present invention. FIG. 13 is a diagram illustrating an example of a determination result in a state in which hyperparameters are not optimized. FIG. 13 is a diagram illustrating an example of a determination result in a state in which hyperparameters are optimized.

The following describes an embodiment of the present invention.

With reference to FIG. 1, a diagnostic system 1 according to one embodiment of the present invention will be described. The diagnostic system 1 is a system that diagnoses the deterioration state of an electrical device 10. The diagnostic system 1 includes a diagnostic device 20 and a terminal device 30. In the example shown in FIG. 1, the diagnostic device 20 is incorporated in the electrical device 10 that is the target of the diagnosis of the deterioration state. In FIG. 1, a configuration in which one diagnostic device 20 is incorporated in one electrical device 10 is shown, but a configuration in which multiple diagnostic devices 20 are incorporated in one electrical device 10 may also be used. Also, a configuration in which one or more diagnostic devices 20 are incorporated in each of multiple electrical devices 10 may also be used.

The diagnostic device 20 and the terminal device 30 can communicate with each other via a network 40. The network 40 may be a network capable of wireless communication or a network capable of wired communication. Alternatively, the network 40 may be a network that includes both a network capable of wireless communication and a network capable of wired communication.

The electrical equipment 10 is an equipment that is the subject of diagnosis of the deterioration state by the diagnostic system 1 or the diagnostic device 20. The electrical equipment 10 may be any equipment that operates using electricity. For example, the electrical equipment 10 may be any equipment that incorporates a DC circuit, such as a programmable logic controller (PLC) that can control equipment installed in a plant, a sensor, an inverter, a monitoring computer, etc.

The diagnostic device 20 is a device capable of diagnosing the deterioration state of the electrical device 10. The diagnostic device 20 may be pre-installed in the electrical device 10, or may be installed as an additional device in the electrical device 10 after shipment.

The terminal device 30 is an information processing device capable of receiving information on the deterioration state of the electrical equipment 10 from the diagnostic device 20. The terminal device 30 may be a general-purpose information processing device, or an information processing device dedicated to the diagnostic system 1. When the terminal device 30 is a general-purpose information processing device, the terminal device 30 may be, for example, a smartphone, a tablet terminal, a notebook PC (Personal Computer), a desktop PC, or a server. By the terminal device 30 receiving information on the deterioration state of the electrical equipment 10 from the diagnostic device 20, the operator of the terminal device 30 can know the deterioration state of the electrical equipment 10 even in a remote location of the electrical equipment 10.

Referring to FIG. 2, the diagnostic device 20 is shown incorporated into the electrical device 10. In the example shown in FIG. 2, the electrical device 10 includes circuit modules 11-1 to 11-N and a base board 12. Hereinafter, when there is no need to distinguish between the circuit modules 11-1 to 11-N, they may simply be referred to as circuit modules 11.

In FIG. 2, the electrical device 10 is shown to have N circuit modules 11-1 to 11-N, but the electrical device 10 may have any number of circuit modules 11.

The circuit module 11 includes a circuit for realizing a specific function. The circuit module 11 may be, for example, a power supply module, a CPU (Central Processing Unit) module, an I/O module, an analog input module, a digital input module, or a motor control module. The circuit module 11 may include, for example, resistors, capacitors, inductors, diodes, transistors, or transformers as circuit components.

The circuit module 11 is connected to the base board 12 via a power supply line 13 and a GND line 14. The power supply line 13 is a wiring to which a DC voltage generated by the circuit module 11 or a DC voltage supplied to the circuit module 11 is applied. For example, if the circuit module 11-1 is a power supply module, the circuit module 11-1 is connected to the base board 12 via the power supply line 13 to which the DC voltage generated by the circuit module 11-1 is applied. Also, for example, if the circuit module 11-2 is a CPU module, the circuit module 11-2 is connected to the base board 12 via the power supply line 13 to which the DC voltage supplied to the circuit module 11-2 is applied.

The base board 12 is electrically connected to each circuit module 11. Each circuit module 11 may be electrically connected to each other via the base board 12. For example, circuit module 11-1 and circuit module 11-2 may be electrically connected via the base board 12. In FIG. 2, only the power supply line 13 and the GND line 14 are shown as wiring connecting the circuit module 11 and the base board 12, but there may also be a signal line as wiring connecting the circuit module 11 and the base board 12.

In the example shown in FIG. 2, the diagnostic device 20 is installed inside the electrical device 10 so as to detect the voltage and current of the power supply line 13 connecting the circuit module 11-1 and the base board 12. In this case, the diagnostic device 20 can diagnose the deterioration state of the circuit module 11-1. The configuration shown in FIG. 2 is one example, and the diagnostic device 20 may be installed so as to detect the voltage and current of the power supply line 13 connecting other circuit modules 11 and the base board 12. Furthermore, multiple diagnostic devices 20 may be installed inside the electrical device 10.

In FIG. 2, the diagnostic device 20 is shown installed inside the electrical device 10, but the installation location of the diagnostic device 20 is not limited to inside the electrical device 10. The diagnostic device 20 may be installed outside the electrical device 10 as long as it can detect the voltage and current of the power line 13 connecting the circuit module 11, which is the subject of the diagnosis of the deterioration state, and the base board 12.

(Hardware configuration of diagnostic device)
3, a hardware configuration of the diagnostic device 20 will be described. The diagnostic device 20 includes an AC voltage application unit 21, a voltage detection unit 22, a current detection unit 23, a filter 24, a communication unit 25, a storage unit 26, and a control unit 27.

The AC voltage application unit 21 is a voltage application means capable of applying an AC voltage to the power line 13. When the AC voltage application unit 21 applies an AC voltage to the power line 13, an AC current flows in the power line 13. The AC voltage application unit 21 may be a current application means capable of flowing an AC current in the power line 13. When the AC voltage application unit 21 flows an AC current in the power line 13, an AC voltage is applied to the power line 13. That is, whether the AC voltage application unit 21 applies an AC voltage to the power line 13 or flows an AC current in the power line 13, the same event occurs in the power line 13. Therefore, the fact that the AC voltage application unit 21 is capable of applying an AC voltage to the power line 13 is synonymous with the fact that the AC voltage application unit 21 is capable of flowing an AC current in the power line 13. Hereinafter, the AC voltage application unit 21 will be described as applying an AC voltage to the power line 13. However, the same effect can be obtained if the AC voltage application unit 21 passes an AC current through the power supply line 13. This is because, in this case, an AC voltage is ultimately applied to the power supply line 13.

The AC voltage application unit 21 includes a signal generator capable of generating an AC voltage. The AC voltage application unit 21 is connected to the power supply line 13 to which the circuit module 11 to be diagnosed is connected, and to the GND line 14 to which the circuit module 11 to be diagnosed is connected. The AC voltage application unit 21 is capable of applying an AC voltage to the power supply line 13 to which the circuit module 11 to be diagnosed is connected.

The voltage detection unit 22 is a voltage detection means capable of detecting the voltage of the power supply line 13. The voltage detection unit 22 may be any type of voltage sensor. The voltage detection unit 22 is connected to the power supply line 13 to which the circuit module 11 to be diagnosed is connected, and to the GND line 14 to which the circuit module 11 to be diagnosed is connected. The voltage detection unit 22 detects the voltage of the power supply line 13 to which the circuit module 11 to be diagnosed is connected.

The current detection unit 23 is a current detection means capable of detecting the current flowing through the power supply line 13. The current detection unit 23 may be any type of current sensor. The current detection unit 23 is connected to the power supply line 13 to which the circuit module 11 to be diagnosed is connected. The current detection unit 23 detects the current flowing through the power supply line 13 to which the circuit module 11 to be diagnosed is connected.

The filter 24 is a filter capable of attenuating signals of frequency components other than a predetermined frequency range. The filter 24 may be, for example, a band-pass filter or a low-pass filter. The filter 24 attenuates frequency components of the noise voltage generated in the power supply line 13 to which the circuit module 11 to be diagnosed is connected, the frequency components other than the predetermined frequency range. Here, the predetermined frequency range is the frequency range of the AC voltage applied to the power supply line 13 by the AC voltage application unit 21. For example, when the AC voltage application unit 21 applies AC voltages of multiple frequencies between 10 Hz and 100 kHz to the power supply line 13, the predetermined frequency range is 10 Hz to 100 kHz. The filter 24 may be connected in parallel, for example, between the power supply line 13 to which the circuit module 11 to be diagnosed is connected and the GND line 14 to which the circuit module 11 to be diagnosed is connected. The filter 24 may also be arranged, for example, in the front or rear stage of the AC voltage application unit 21. When placed in front of the AC voltage application unit 21, the filter 24 may be a low-pass filter.

When the filter 24 is a bandpass filter, the filter 24 may be configured to switch between multiple bandpass filters. In this case, the filter 24 may switch the bandpass filter to be used depending on the frequency of the AC voltage that the AC voltage application unit 21 applies to the power line 13.

When the filter 24 is a low-pass filter and the low-pass filter is placed in front of the AC voltage application unit 21, the filter 24 can be configured as a single low-pass filter. In this case, the filter 24 can be realized with a simple configuration.

The communication unit 25 is one or more communication interfaces that communicate with external devices wirelessly or via wires. The communication unit 25 includes a communication interface that communicates with the terminal device 30 via the network 40.

The storage unit 26 is one or more memories. In this embodiment, the "memory" is, for example, a semiconductor memory, a magnetic memory, or an optical memory, but is not limited to these and can be any memory. The storage unit 26 may function as, for example, a main memory device, an auxiliary memory device, or a cache memory. The storage unit 26 is, for example, built into the diagnostic device 20, but can also be configured to be connected externally to the diagnostic device 20 via any interface.

The control unit 27 is one or more processors. In this embodiment, the "processor" may be a general-purpose processor, a dedicated processor specialized for a specific process, or the like, but is not limited to these and may be any processor. The control unit 27 controls the operation of the entire diagnostic device 20. The operation of the diagnostic device 20 will be described in detail later.

(Hardware configuration of terminal device)
The hardware configuration of the terminal device 30 will be described with reference to Fig. 4. The terminal device 30 includes a communication unit 31, a storage unit 32, a display unit 33, and a control unit 34.

The communication unit 31 is one or more communication interfaces that communicate with an external device wirelessly or via a wired connection. The communication unit 31 includes a communication interface that communicates with the diagnostic device 20 via the network 40.

The storage unit 32 is one or more memories. The storage unit 32 may function as, for example, a main storage device, an auxiliary storage device, or a cache memory. The storage unit 32 is, for example, built into the terminal device 30, but may also be configured to be connected externally to the terminal device 30 via any interface.

The display unit 33 is any display. For example, the display unit 33 may be a liquid crystal display or an OEL (Organic Electro-luminescence) display.

The control unit 34 is one or more processors. The control unit 34 controls the operation of the entire terminal device 30.

(Software configuration of diagnostic device)
The software configuration of the diagnostic device 20 will be described with reference to Fig. 3. One or more programs used to control the operation of the diagnostic device 20 are stored in the storage unit 26. When the one or more programs are loaded by the control unit 27, they cause the control unit 27 to function as an impedance calculation means 271, a determination means 272, a noise voltage detection means 273, and a parameter estimation means 274.

An overview of each means of the control unit 27 is given below.

The impedance calculation means 271 is a means for calculating the impedance of the circuit module 11 connected to the power supply line 13 based on the voltage of the power supply line 13 detected by the voltage detection unit 22 and the current of the power supply line 13 detected by the current detection unit 23.

The determination means 272 is a means for determining the deterioration state of the circuit module 11 based on the impedance calculated by the impedance calculation means 271.

The noise voltage detection means 273 is a means for detecting the maximum value of the noise voltage occurring on the power supply line 13 based on the voltage of the power supply line 13 detected by the voltage detection unit 22 while the electrical device 10 is operating.

The parameter estimation means 274 estimates the parameters of each circuit component of the circuit module 11 represented as an equivalent circuit based on the impedance calculated by the impedance calculation means 271.

(Operation of diagnostic device)
The following describes the operation of the diagnostic device 20. In this embodiment, as shown in FIG. 2, a case will be described in which the diagnostic device 20 diagnoses the circuit module 11-1 for its degradation state.

The AC voltage application unit 21 applies an AC voltage to the power supply line 13 to which the circuit module 11-1 is connected, based on instructions from the control unit 27, while the electrical device 10 is operating. FIG. 5 shows a conceptual diagram of when an AC voltage V (hereinafter also simply referred to as "voltage V") is applied to the power supply line 13 to which the circuit module 11-1 is connected. As shown in FIG. 5, when voltage V is applied to the power supply line 13, an AC current I (hereinafter also simply referred to as "current I") flows through the power supply line 13.

The current I flowing through the power supply line 13 depends on the impedance Z of the circuit module 11-1 to which the power supply line 13 is connected. The impedance calculation means 271 calculates the impedance Z of the circuit module 11-1 based on the voltage V detected by the voltage detection unit 22 and the current I detected by the current detection unit 23, using the following formula (1).
Z = V / I (1)

6 shows an example of the voltage V detected by the voltage detection unit 22 and the current I detected by the current detection unit 23. The impedance calculation means 271 may calculate the absolute value |Z| of the impedance Z of the circuit module 11-1 based on the amplitude |V| of the voltage V detected by the voltage detection unit 22 and the amplitude |I| of the current I detected by the current detection unit 23, using the following formula (2).
|Z|=|V|/|I| (2)

In addition, the impedance calculation means 271 may calculate the phase θ of the impedance Z of the circuit module 11-1 based on the phase ArgV of the voltage V detected by the voltage detection unit 22 and the phase ArgI of the current I detected by the current detection unit 23 using the following equation (3).
θ=ArgV−ArgI (3)

The AC voltage application unit 21 applies AC voltages of multiple frequencies to the power supply line 13 while the electrical device 10 is operating, based on instructions from the control unit 27. The multiple frequencies applied by the AC voltage application unit 21 may be frequencies that are preset as appropriate frequencies for measuring the impedance Z of the circuit module 11-1. For example, the AC voltage application unit 21 applies AC voltages of multiple frequencies within a frequency range of 10 Hz to 100 kHz to the power supply line 13.

The impedance calculation means 271 can calculate the impedance if the voltage detection unit 22 and the current detection unit 23 detect the voltage and current for at least one wavelength, respectively. The AC voltage application unit 21 may apply an AC voltage for a predetermined number of wavelengths to the power line 13 so that the impedance calculation means 271 can calculate the average value of the impedance. The AC voltage application unit 21 may apply an AC voltage for, for example, 10 wavelengths to the power line 13. In this way, by calculating the average value of the impedance using the voltage and current for multiple wavelengths, the impedance calculation means 271 can calculate the impedance of the power line 13 with high accuracy.

When applying an AC voltage of, for example, 10 wavelengths to the power supply line 13, the AC voltage application unit 21 applies an AC voltage of 10 wavelengths at a certain frequency, and then applies an AC voltage of 10 wavelengths at the next set frequency. In this way, by applying an AC voltage of a predetermined number of wavelengths at any frequency setting, the AC voltage application unit 21 can optimize the measurement time, and can calculate the average impedance value in a necessary and sufficient time at any frequency setting.

For example, consider a case where the AC voltage application unit 21 applies an AC voltage of a certain frequency to the power line 13 for a fixed period of time regardless of the frequency setting. In this case, for example, if the frequency of the AC voltage applied by the AC voltage application unit 21 is low, only a small number of wavelengths of AC voltage can be applied to the power line 13, and it may happen that the impedance calculation means 271 cannot calculate the average impedance value with high accuracy. Also, for example, if the frequency of the AC voltage applied by the AC voltage application unit 21 is high, a very large number of wavelengths of AC voltage may be applied to the power line 13, and it may happen that the impedance calculation means 271 takes an excessively long time to measure the impedance than is necessary to calculate the average impedance value.

In contrast, by applying an AC voltage for a predetermined number of wavelengths at any frequency setting, the AC voltage application unit 21 can optimize the measurement time and calculate the average impedance value in a sufficient amount of time at any frequency setting.

The AC voltage application unit 21 applies an AC voltage to the power supply line 13, the amplitude of which is determined according to the electrical device 10 and does not affect the operation of the electrical device 10. In this way, by setting the amplitude of the AC voltage applied to the power supply line 13 by the AC voltage application unit 21 to an amplitude that does not affect the operation of the electrical device 10, the AC voltage application unit 21 can apply an AC voltage to the power supply line 13 without affecting the operation of the electrical device 10, even when the electrical device 10 is in operation.

The amplitude of the AC voltage applied by the AC voltage application unit 21 to the power supply line 13 may be, for example, an amplitude determined according to the magnitude of the DC voltage of the power supply line 13. For example, when the electrical device 10 is a PLC, the DC voltage of the power supply line 13 is often about 24 V. In this case, the amplitude of the AC voltage applied by the AC voltage application unit 21 to the power supply line 13 may be determined with an upper limit of about ±0.1% (24 mV) of DC 24 V, taking into consideration the position of application.

The amplitude of the AC voltage applied by the AC voltage application unit 21 to the power supply line 13 may be, for example, an amplitude smaller than the maximum value of the noise voltage generated on the power supply line 13 while the electrical device 10 is operating. In this way, if the AC voltage has an amplitude smaller than the maximum value of the noise voltage originally generated on the power supply line 13 while the electrical device 10 is operating, the operation of the electrical device 10 is not affected even if it is applied to the power supply line 13 while the electrical device 10 is operating.

The magnitude of the noise voltage generated on the power line 13 while the electrical device 10 is operating may be detected by the noise voltage detection means 273 when the electrical device 10 is operating in an environment in which the electrical device 10 is actually used, and stored in the memory unit 26. Alternatively, the magnitude of the noise voltage may be stored in advance in the memory unit 26 as a value determined according to the specifications of the electrical device 10. The noise voltage detection means 273 may also calculate a value corresponding to the electrical device 10 based on these noise voltages stored in the memory unit 26. In this case, the noise voltage detection means 273 may use a learning function to calculate a value corresponding to the electrical device 10 based on these noise voltages stored in the memory unit 26, for example.

The impedance calculation means 271 may plot the impedances calculated at multiple frequencies on a complex plane to create a Nyquist diagram. FIG. 7 shows an example of a Nyquist diagram created by the impedance calculation means 271. The Nyquist diagram shown in FIG. 7 is a Nyquist diagram when the impedance calculation means 271 calculates the impedance of a circuit module 11 whose equivalent circuit has the configuration shown in FIG. 8.

The complex plane shown in FIG. 7 has Re(Z) on the horizontal axis and -Im(Z) on the vertical axis. In the example shown in FIG. 7, the AC voltage application unit 21 applies AC voltages to the power supply line 13 at five frequencies f1 to f5. The impedance calculation means 271 calculates five impedances Z1 to Z5 for each of the five frequencies f1 to f5, and creates a Nyquist diagram by plotting these five impedances Z1 to Z5 on the complex plane.

In the example shown in Figure 7, Z1 is the impedance when the frequency is low, and Z5 is the impedance when the frequency is high. Referring to the equivalent circuit shown in Figure 8, when the frequency is low, capacitor Cp approaches open, so the impedance of the equivalent circuit when the frequency is low approaches Rs + Rp. Also, when the frequency is high, capacitor Cp approaches short, so the impedance of the equivalent circuit when the frequency is high approaches Rs. Referring to Figure 7, at low frequencies the impedance approaches Rs + Rp, and at high frequencies the impedance approaches Rs.

The parameter estimation means 274 has a function of performing calculations using the equivalent circuit model and the parameters of the given equivalent circuit, and simulating the Nyquist diagram. Furthermore, the parameter estimation means 274 repeats the simulation of the Nyquist diagram while gradually changing the parameters of the equivalent circuit model so as to reduce the error with the actually measured Nyquist diagram created by the impedance calculation means 271. In this way, the parameter estimation means 274 estimates the parameters of the actual equivalent circuit.

The equivalent circuit of the circuit module 11 is created in advance based on the circuit configuration of the circuit module 11 and is stored in the storage unit 26. In addition, the initial values of the parameters of the equivalent circuit of the circuit module 11 are also stored in advance in the storage unit 26.

The determination means 272 calculates the difference between the parameter estimated by the parameter estimation means 274 and the initial value of the parameter for each circuit component of the equivalent circuit of the circuit module 11. Here, the "initial value of the parameter" may be the parameter value of a new PLC, for example, when the electrical device 10 is a PLC. The determination means 272 compares the calculated difference with a threshold value set for each circuit component. If the parameter difference calculated for a certain circuit component is greater than the threshold value, the determination means 272 determines that the circuit component is degraded. Note that the object for which the determination means 272 calculates the difference for the estimated parameter is not limited to the initial value of the parameter. For example, the determination means 272 may calculate the difference between the estimated parameter and the most recent past value of the parameter, or may calculate the difference between the estimated parameter and the average value of multiple most recent past data of the parameter.

The determination means 272 may transmit the determination result as to whether or not each circuit component of the equivalent circuit of the circuit module 11 has deteriorated to the terminal device 30 via the communication unit 25.

The terminal device 30 receives the judgment result by the judgment means 272 from the diagnostic device 20. The terminal device 30 may display the received judgment result on the display unit 33. In this way, by receiving the judgment result by the judgment means 272 from the diagnostic device 20, the operator of the terminal device 30 can know whether or not there is deterioration in the electrical device 10 even in a remote location.

Next, the operation of the diagnostic device 20 according to one embodiment of the present invention will be described with reference to the flowchart shown in FIG.

The flowchart shown in FIG. 9 shows the process by which the diagnostic device 20 diagnoses the electrical device 10 to be diagnosed. The diagnostic device 20 may execute the process shown in FIG. 9 periodically, or may execute it on demand in response to an instruction from a user. When executed periodically, the diagnostic device 20 may execute the process shown in FIG. 9 with a frequency of, for example, once a week or once a month.

Step S101: The control unit 27 sets the frequency of the AC voltage to be applied to the power supply line 13 to which the circuit module 11 to be diagnosed is connected to the first frequency of multiple frequencies to be applied.

Step S102: The AC voltage application unit 21 applies an AC voltage of the frequency instructed by the control unit 27 to the power line 13.

Step S103: The voltage detection unit 22 detects the voltage of the power supply line 13. The current detection unit 23 detects the current flowing through the power supply line 13.

Step S104: The impedance calculation means 271 calculates the impedance of the circuit module 11 to be diagnosed based on the voltage detected by the voltage detection unit 22 and the current detected by the current detection unit 23. At this time, the impedance calculation means 271 may calculate an average value of the impedance based on the voltage detected by the voltage detection unit 22 and the current detected by the current detection unit 23 for the AC voltage applied for a predetermined number of wavelengths. The impedance calculation means 271 stores the calculated impedance in the memory unit 26.

Step S105: The control unit 27 determines whether all of the multiple frequencies to be applied to the power line 13 have been applied to the power line 13. If all of the frequencies have not yet been applied to the power line 13 (No in step S105), the control unit 27 proceeds to step S106. If all of the frequencies have been applied to the power line 13, the control unit 27 proceeds to step S107.

Step S106: The control unit 27 sets the frequency of the AC voltage applied to the power line 13 to the next frequency and returns to step S102.

Step S107: The impedance calculation means 271 creates a Nyquist diagram based on the multiple impedances stored in the memory unit 26.

Step S108: The parameter estimation means 274 repeats the simulation of the Nyquist diagram while gradually changing the parameters of the equivalent circuit model so as to reduce the error with the Nyquist diagram created in step S107. In this way, the parameter estimation means 274 estimates the parameters of the equivalent circuit of the circuit module 11.

Step S109: The determination means 272 calculates the difference between the parameters estimated by the parameter estimation means 274 and the initial values of the parameters for each circuit component of the equivalent circuit of the circuit module 11.

Step S110: The determination means 272 determines whether the difference calculated for each circuit component of the equivalent circuit in step S109 is greater than the threshold value set for each circuit component. If the difference is equal to or less than the threshold value (No in step S110), the determination means 272 proceeds to step S111. If the difference is greater than the threshold value (Yes in step S110), the determination means 272 proceeds to step S112.

Step S111: If there is no circuit component whose difference is greater than the threshold, the determination means 272 determines that there is no degraded circuit component.

Step S112: If there is a circuit component whose difference is greater than the threshold, the determination means 272 determines that there is a degraded circuit component.

After step S111 or step S112, the determination means 272 may transmit the determination result as to whether or not there is a degraded circuit component to the terminal device 30 via the communication unit 25.

(Determination using machine learning)

When judging the degradation state of the circuit module 11 based on the impedance calculated by the impedance calculation means 271, the judgment means 272 may judge the degradation state of the circuit module 11 based on a learning model machine-learned using the impedance of the circuit module 11. In this way, by making a judgment using the machine-learned learning model, the judgment means 272 can improve the accuracy of judging the degradation state of the circuit module 11.

The impedance data obtained by measuring the impedance of the circuit module 11 while the circuit module 11 is actually operating can be used as learning data for machine learning the learning model used by the determination means 272 when determining the deterioration state of the circuit module 11.

When measuring the impedance of the circuit module 11, an AC voltage is applied to the circuit module 11 while the circuit module 11 is operating, and the impedance is measured based on the voltage and current detected at that time. When measuring the impedance of the circuit module 11, AC voltages of multiple frequencies may be applied to the circuit module 11. The frequency range of the AC voltage applied to the circuit module 11 may be, for example, from 10 Hz to 100 kHz.

When the impedance of a circuit module 11 that has been confirmed to be operating normally is measured, the measured impedance data can be used as learning data that corresponds to the impedance of the circuit module 11 under normal conditions.

When the impedance of a circuit module 11 that has been confirmed to be operating abnormally is measured, the measured impedance data can be used as learning data that corresponds to the impedance of the circuit module 11 when it is abnormal.

The learning model used by the determination means 272 when determining the degradation state of the circuit module 11 may be machine-learned using learning data measured using the circuit module 11. The learning model is machine-learned using learning data corresponding to the impedance of the circuit module 11 when it is normal and learning data corresponding to the impedance of the circuit module 11 when it is abnormal.

When the determination means 272 determines the deterioration state of the circuit module 11 based on the impedance calculated by the impedance calculation means 271, the determination means 272 may determine the deterioration state of the circuit module 11 based on a learning model that has been machine-learned using a simulated circuit of the circuit module 11, instead of a learning model that has been machine-learned using the impedance of the circuit module 11.

The simulated circuit of the circuit module 11 is a circuit in which a circuit equivalent to the equivalent circuit of the circuit module 11 is implemented on a substrate or the like using actual circuit elements. The circuit elements included in the simulated circuit may be, for example, resistors, capacitors, inductors, diodes, transistors, transformers, etc. The simulated circuit may be, for example, a general-purpose printed circuit board on which general-purpose resistors, capacitors, inductors, diodes, transistors, transformers, etc. are implemented.

The simulation circuit is configured to be able to simulate failures that are expected to occur in the circuit module 11.

For example, consider a case where a capacitor is included in the equivalent circuit of the circuit module 11, and a failure in the circuit module 11 that increases the internal resistance of the capacitor is assumed to occur. In this case, the simulated circuit includes a configuration in which a capacitor and a resistor are connected in series. The capacitor included in the simulated circuit corresponds to the capacitor assumed to fail. The resistor connected in series to the capacitor corresponds to the internal resistance of the capacitor assumed to fail. The resistance value of the resistor corresponding to the internal resistance can be changed. The resistance value of the resistor corresponding to the internal resistance can be switched between at least the resistance value of the internal resistance of the capacitor in normal times and the resistance value of the internal resistance of the capacitor assumed to fail. The state in which the resistance value of the resistor included in the simulated circuit that corresponds to the internal resistance of the capacitor is switched to the resistance value of the internal resistance of the capacitor assumed to fail is also referred to as a "simulated failure".

The impedance data obtained by measuring the impedance of the simulated circuit while the simulated circuit is actually operating can be used as learning data for machine learning the learning model used by the determination means 272 when determining the deterioration state of the circuit module 11.

When measuring the impedance of the simulated circuit, an AC voltage is applied to the simulated circuit while the simulated circuit is operating, and the impedance is measured based on the voltage and current detected at that time. When measuring the impedance of the simulated circuit, AC voltages of multiple frequencies may be applied to the simulated circuit. The frequency range of the AC voltage applied to the simulated circuit may be, for example, from 10 Hz to 100 kHz.

When the impedance of the simulated circuit is measured with the resistance value of the resistor included in the simulated circuit set to the resistance value of the internal resistance of the capacitor under normal conditions, the measured impedance data can be used as learning data equivalent to the impedance of the circuit module 11 under normal conditions.

When the impedance of the simulated circuit is measured with the resistance value of the resistor included in the simulated circuit set to the resistance value of the internal resistance of the capacitor expected in the event of a failure, the measured impedance data can be used as learning data equivalent to the impedance of the circuit module 11 in the event of an abnormality.

The learning model used by the determination means 272 when determining the degradation state of the circuit module 11 may be machine-learned using learning data measured using a simulated circuit. The learning model is machine-learned using learning data corresponding to the impedance of the circuit module 11 in a normal state measured using a simulated circuit, and learning data corresponding to the impedance of the circuit module 11 in an abnormal state measured using a simulated failure of the simulated circuit.

To increase the amount of learning data, the temperature of the environment in which the circuit module 11 or simulated circuit is installed may be changed to measure the impedance of the circuit module 11 or simulated circuit at various temperatures. For example, the temperature of the environment in which the circuit module 11 or simulated circuit is installed can be changed by placing the circuit module 11 or simulated circuit in a thermostatic chamber. The range in which the temperature is changed may be the range of temperatures expected as the temperature of the environment in which the circuit module 11 is installed. The range in which the temperature is changed may be, for example, 10°C to 50°C.

When increasing the amount of learning data to be measured with the simulated circuit, multiple pieces of learning data corresponding to the impedance in the normal state can be obtained by changing the temperature and measuring the impedance of the simulated circuit while the resistance value of the resistor included in the simulated circuit is set to the resistance value of the internal resistance of the capacitor in the normal state. Also, multiple pieces of learning data corresponding to the impedance in the abnormal state can be obtained by changing the temperature and measuring the impedance of the simulated circuit while the resistance value of the resistor included in the simulated circuit is set to the resistance value of the internal resistance of the capacitor assumed in the event of a failure.

The learning data obtained by changing the temperature may be used in the machine learning of the learning model as data not associated with temperature. In other words, when using the learning data in the machine learning of the learning model, the learning data does not need to include information on the temperature at which the learning data was obtained. This is because the range in which the temperature is changed is the range of temperatures expected as the temperature of the environment in which the circuit module 11 is installed, so that, for example, all of the learning data obtained by changing the temperature in a state where the resistance value of the internal resistance of the capacitor is normal can be used as learning data for normal times. By not including temperature information in the learning data in this way, it is possible to reduce the dimension of the learning data by the temperature parameter, and it is possible to speed up the machine learning processing.

A learning model that has been machine-trained based on normal learning data and abnormal learning data acquired using the circuit module 11 or the simulated circuit may be stored in the memory unit 26 of the diagnostic device 20. The determination means 272 determines the deterioration state of the circuit module 11 based on the learning model stored in the memory unit 26.

The machine learning algorithm may be, for example, OCSVM (One Class Support Vector Machine). In this case, the machine learning algorithm has parameters called hyperparameters. The hyperparameters include nu (ν) and gamma (γ) as parameters. Nu is a parameter related to the proportion of abnormal data contained in the training data. Gamma is a parameter that determines the complexity of the boundary surface, and the larger gamma is, the greater the complexity of the boundary surface.

The hyperparameters of the learning model used by the determination means 272 may be optimized based on normal learning data and abnormal learning data acquired using a simulated circuit. By optimizing the hyperparameters, the determination means 272 can further improve the accuracy in determining the deterioration state of the circuit module 11.

The difference in judgment accuracy between a state in which hyperparameters are not optimized and a state in which hyperparameters are optimized will be described with reference to Figures 10 and 11. Figure 10 is a diagram showing an example of a judgment result in a state in which hyperparameters are not optimized. Figure 11 is a diagram showing an example of a judgment result in a state in which hyperparameters are optimized.

In Figures 10 and 11, the horizontal axis indicates the data number. The data number is a number assigned to each piece of impedance data obtained using a simulated circuit. For example, a data number of "1" indicates that it is the first piece of data obtained. In the example shown in Figures 10 and 11, data with data numbers 1 to 38 are impedance data measured when the resistance value of the resistor included in the simulated circuit is set to the resistance value of the internal resistance of the capacitor under normal conditions. Data with data numbers 39 to 73 are impedance data measured when the resistance value of the resistor included in the simulated circuit is set to the resistance value of the internal resistance of the capacitor assumed to be in the event of a failure.

In Figures 10 and 11, the vertical axis indicates the normality value output by the machine learning algorithm. If the normality is equal to or greater than a predetermined threshold, the determination means 272 determines that the impedance is normal. If the normality is less than the predetermined threshold, the determination means 272 determines that the impedance is abnormal.

The symbols of white circles, black circles, white triangles, and black triangles shown in FIG. 10 and FIG. 11 respectively have the following meanings.
Open circles: Data measuring normal impedance is judged to be normal. Closed circles: Data measuring normal impedance is judged to be abnormal. Open triangles: Data measuring abnormal impedance is judged to be abnormal. Closed triangles: Data measuring abnormal impedance is judged to be normal. In other words, the higher the proportion of open circles and open triangles compared to the proportion of closed circles and closed triangles, the higher the judgment accuracy.

Fig. 10 is a diagram showing an example of a determination result in a state in which the hyperparameters are not optimized. In the example shown in Fig. 10, the hyperparameters are set as follows.
Nu (ν): 0.3
Gamma (γ): 0.1
10, there are many black circles and black triangles, which means that the accuracy of the determination is low.

Fig. 11 is a diagram showing an example of a determination result in a state in which hyperparameters are optimized. In the determination shown in Fig. 11, the hyperparameters are set as follows.
Nu (ν): 0.01
Gamma (γ): 0.5
11, there is only one black circle and zero black triangles. In other words, the accuracy of the determination is high. In this way, the accuracy of the determination can be improved by optimizing the hyperparameters.

As described above, according to the diagnostic device 20 of this embodiment, when the impedance calculation means 271 calculates the impedance of the circuit module 11, an AC voltage having an amplitude determined according to the electrical device 10 is applied to the power supply line 13 by the AC voltage application unit 21. In this way, since the AC voltage application unit 21 applies an AC voltage having an amplitude determined according to the electrical device 10 to the power supply line 13, which does not affect the operation of the electrical device 10, the diagnostic device 20 can diagnose the deterioration state of the electrical device 10 based on the calculated impedance while the electrical device 10 is in operation. Therefore, the technology related to diagnosing the deterioration state of the electrical device 10 can be improved.

Although the present invention has been described based on the drawings and embodiments, it should be noted that a person skilled in the art would easily be able to make various modifications and corrections based on this disclosure. Therefore, it should be noted that these modifications and corrections are included in the scope of the present invention. For example, the functions included in each means, step, etc. can be rearranged so as not to cause logical inconsistencies, and multiple means and steps, etc. can be combined into one or divided.

For example, the diagnostic system 1 may be equipped with multiple information processing devices, and each configuration or each means of the diagnostic device 20 or terminal device 30 according to the above-mentioned embodiment may be distributed among the multiple information processing devices. For example, among the multiple information processing devices, a first information processing device may function as some of the means of the impedance calculation means 271, the determination means 272, the noise voltage detection means 273, and the parameter estimation means 274, and a second information processing device may function as the remaining means. The above examples of distributed arrangement of the multiple means are not limited to this, and the means may be distributed among any number of information processing devices.

The storage unit 32 of the terminal device 30 may store at least one of the programs that cause the control unit 34 to function as the impedance calculation means 271, the determination means 272, the noise voltage detection means 273, and the parameter estimation means 274. In this case, the terminal device 30 may execute the functions of at least one of the impedance calculation means 271, the determination means 272, the noise voltage detection means 273, and the parameter estimation means 274, instead of the diagnostic device 20.

In addition, in the above-described embodiment, the diagnostic device 20 may be configured as an integral part of the base board 12 of the electrical device 10.

REFERENCE SIGNS LIST 1 diagnostic system 10 electrical device 11 circuit module 12 base board 13 power supply line 14 GND line 20 diagnostic device 21 AC voltage application section 22 voltage detection section 23 current detection section 24 filter 25 communication section 26 memory section 27 control section 271 impedance calculation means 272 determination means 273 noise voltage detection means 274 parameter estimation means 30 terminal device 31 communication section 32 memory section 33 display section 34 control section 40 network

Claims (11)

A diagnostic device for diagnosing a deterioration state of an electrical device, comprising:
an AC voltage application unit capable of applying an AC voltage or passing an AC current to a power supply line connected to a circuit module included in the electrical device;
an impedance calculation means for calculating an impedance of the circuit module based on a voltage and a current of the power supply line to which an AC voltage is applied by the AC voltage application unit while the electrical device is in operation;
a determining means for determining a deterioration state of the circuit module based on the calculated impedance;
a voltage detection unit capable of detecting a voltage of the power supply line;
a noise voltage detection means for detecting a maximum value of a noise voltage occurring on the power supply line based on the voltage of the power supply line detected by the voltage detection unit;
Equipped with
The AC voltage application unit applies, to the power supply line, an AC voltage having an amplitude smaller than a maximum value of the noise voltage detected by the noise voltage detection means. 2. The diagnostic device according to claim 1,
The diagnostic device further comprises a filter that attenuates frequency components occurring in the power supply line that are outside a frequency range of the AC voltage applied by the AC voltage application unit. 3. The diagnostic device according to claim 1,
The AC voltage application unit is
Applying AC voltages of multiple frequencies to the power supply line;
A diagnostic device that switches the frequency of the applied AC voltage to the next frequency when an AC voltage of each of the plurality of frequencies has been applied for a predetermined number of wavelengths. The diagnostic device according to any one of claims 1 to 3,
The determination means determines the deterioration state of the circuit module based on a learning model machine-learned using the impedance of the circuit module. 5. The diagnostic device according to claim 4,
A diagnostic device in which the hyperparameters of the learning model are optimized using the impedance of a simulated circuit of the circuit module. 6. The diagnostic device according to claim 4 or 5,
The learning data used by the determination means to perform machine learning of the learning model is generated by changing a temperature,
A diagnostic device, wherein the learning data is used for machine learning of the learning model as data not associated with temperature. A diagnostic system for diagnosing a deterioration state of an electrical device, comprising:
an AC voltage application unit capable of applying an AC voltage or passing an AC current to a power supply line connected to a circuit module included in the electrical device;
an impedance calculation means for calculating an impedance of the circuit module based on a voltage and a current of the power supply line to which an AC voltage is applied by the AC voltage application unit while the electrical device is in operation;
a determining means for determining a deterioration state of the circuit module based on the calculated impedance;
a voltage detection unit capable of detecting a voltage of the power supply line;
a noise voltage detection means for detecting a maximum value of a noise voltage occurring on the power supply line based on the voltage of the power supply line detected by the voltage detection unit;
Equipped with
The AC voltage application unit applies, to the power supply line, an AC voltage having an amplitude smaller than a maximum value of the noise voltage detected by the noise voltage detection means. a voltage detecting unit capable of detecting a voltage of the power supply line; and a noise voltage detecting unit for detecting a maximum value of a noise voltage generated on the power supply line based on the voltage of the power supply line detected by the voltage detecting unit, wherein the AC voltage applying unit applies an AC voltage to the power supply line , the AC voltage applying unit applying an AC voltage to the power supply line, the noise voltage detecting unit detecting a maximum value of a noise voltage generated on ...
A diagnostic device comprising at least the voltage detection unit, the noise voltage detection unit, and the AC voltage application unit out of the AC voltage application unit, the impedance calculation unit, the determination unit, the voltage detection unit , and the noise voltage detection unit. a base board constituting a diagnostic system for diagnosing a deterioration state of an electrical device, comprising: an AC voltage application unit capable of applying an AC voltage or passing an AC current to a power supply line connected to a circuit module included in an electrical device; impedance calculation means for calculating an impedance of the circuit module based on the voltage and current of the power supply line to which an AC voltage is applied by the AC voltage application unit while the electrical device is in operation; determination means for determining a deterioration state of the circuit module based on the calculated impedance; a voltage detection unit capable of detecting a voltage of the power supply line ; and noise voltage detection means for detecting a maximum value of a noise voltage generated on the power supply line based on the voltage of the power supply line detected by the voltage detection unit, wherein the AC voltage application unit applies to the power supply line an AC voltage having an amplitude smaller than the maximum value of the noise voltage detected by the noise voltage detection means,
a base board including at least the voltage detection unit, the noise voltage detection unit, and the AC voltage application unit out of the AC voltage application unit, the impedance calculation unit, the determination unit, the voltage detection unit , and the noise voltage detection unit; A diagnostic method for diagnosing a deterioration state of an electrical device, comprising:
applying an AC voltage or passing an AC current through a power supply line connected to a circuit module included in the electrical device;
calculating an impedance of the circuit module based on a voltage and a current of the power supply line to which an AC voltage is applied while the electrical device is in operation;
determining a degradation state of the circuit module based on the calculated impedance;
detecting a voltage on the power supply line;
detecting a maximum value of a noise voltage occurring on the power supply line based on the detected voltage of the power supply line ;
Including,
The amplitude of the AC voltage applied to the power line is smaller than a maximum value of the detected noise voltage. A diagnostic device for diagnosing a deterioration state of an electrical device, the diagnostic device including an AC voltage application unit capable of applying an AC voltage or flowing an AC current to a power supply line connected to a circuit module included in the electrical device,
an impedance calculation means for calculating an impedance of the circuit module based on a voltage and a current of the power supply line to which an AC voltage is applied by the AC voltage application unit while the electrical device is in operation;
a determining means for determining a deterioration state of the circuit module based on the calculated impedance;
a voltage detection unit capable of detecting a voltage of the power supply line;
a noise voltage detection means for detecting a maximum value of a noise voltage occurring on the power supply line based on the voltage of the power supply line detected by the voltage detection unit;
Function as a
The AC voltage application unit applies, to the power supply line, an AC voltage having an amplitude smaller than a maximum value of the noise voltage detected by the noise voltage detection means.

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