JP2023023861A - Diagnostic device, power conversion device, diagnostic method, and program - Google Patents

Abstract

To provide a technique capable of diagnosing the degree of deterioration of an AC motor.SOLUTION: A control circuit 70 of a power conversion device 100 according to an embodiment includes: a diagnostic information acquisition unit 701 that acquires information about an electrical physical quantity representing a driving state of an electrical motor EM; a feature quantity acquisition unit 704 that acquires a feature quantity related to temporal changes due to harmonic components of the electrical physical quantity representing the driving state of the electrical motor EM; and a diagnostic unit 706 that diagnoses degree of deterioration of the electrical motor EM based on the feature quantity.SELECTED DRAWING: Figure 6

Description

The present disclosure relates to diagnostic devices and the like.

Conventionally, techniques for diagnosing abnormalities in AC motors are known (see Patent Documents 1 and 2, for example).

JP 2020-114084 A WO2014/156386

However, with the above technology, although it is possible to know the occurrence of an abnormality in the AC motor, it is not possible to know the degree of deterioration (progress of deterioration) of the AC motor.

Therefore, in view of the above problems, it is an object of the present invention to provide a technique capable of diagnosing the degree of deterioration of an AC motor.

To achieve the above objectives, in one embodiment of the present disclosure,
a first information acquisition unit that acquires information about an electrical physical quantity representing the drive state of the AC motor;
a feature quantity acquisition unit that acquires a feature quantity related to the time change of the electrical physical quantity;
a diagnostic unit that diagnoses the degree of progress of deterioration of the AC motor based on the feature amount;
A diagnostic device is provided.

Also, in other embodiments of the present disclosure,
A power conversion device that supplies driving power to the AC motor based on power input from the outside,
comprising a diagnostic device as described above,
A power converter is provided.

In yet another embodiment of the present disclosure,
a first information acquisition step in which the diagnostic device acquires information about an electrical physical quantity representing the driving state of the AC motor;
a feature quantity acquiring step in which the diagnostic device acquires a feature quantity relating to the time change of the electrical physical quantity;
a diagnostic step in which the diagnostic device diagnoses the degree of progress of deterioration of the AC motor based on the feature quantity;
A diagnostic method is provided.

In yet another embodiment of the present disclosure,
diagnostic equipment,
a first information acquisition step of acquiring information about an electrical physical quantity representing the drive state of the AC motor;
a feature amount acquiring step of acquiring a feature amount related to the time change of the electrical physical quantity;
a diagnostic step of diagnosing the degree of progress of deterioration of the AC motor based on the feature quantity;
A program is provided.

According to the above-described embodiments, it is possible to diagnose the degree of deterioration of the AC motor.

It is a figure which shows an example of the hardware constitutions of a diagnostic system. It is a figure which shows an example of the hardware constitutions of a management apparatus. It is a functional block diagram showing an example of functional composition about a diagnostic function of a power converter (control circuit). It is a figure which shows an example of the result of a waveform counting process and a feature-value acquisition process. FIG. 7 is a diagram showing an example of the distribution of the number of occurrences of cycle change values when an abnormality occurs due to deterioration of an electric motor; 4 is a main flowchart schematically showing an example of diagnostic processing; 4 is a sub-flowchart schematically showing an example of diagnostic processing;

Embodiments will be described below with reference to the drawings.

[Hardware configuration of diagnostic system]
A hardware configuration of a diagnostic system 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG.

FIG. 1 is a diagram showing an example of a hardware configuration of a diagnostic system 1 according to this embodiment. FIG. 2 is a diagram showing an example of the hardware configuration of the management device 200 according to this embodiment.

Since the hardware configuration of the terminal device 300 is the same as that of the management device 200, illustration and detailed description thereof will be omitted.

As shown in FIG. 1 , diagnostic system 1 includes electric motor EM, power conversion device 100 , management device 200 , and terminal device 300 .

An electric motor EM (an example of an AC motor) drives, for example, production equipment and mechanical equipment installed in a factory. The electric motor EM is, for example, an induction motor.

Power conversion device 100 converts three-phase AC power (eg, R-phase, S-phase, and T-phase) input from commercial power source PS into three-phase AC power (eg, U-phase, V phase, and W phase) to drive the motor EM.

The power converter 100 includes a rectifier circuit 10, a smoothing circuit 20, an inverter circuit 30, a current sensor 40, a voltage sensor 50, a gate drive circuit 60, a control circuit 70, a display section 80, and a communication section 90. including.

Rectifier circuit 10 is configured to rectify three-phase AC power input from commercial power supply PS and output DC power. The rectifier circuit 10 has positive and negative output terminals connected to one end of a positive line PL and a negative line NL, respectively, and can output DC power to the smoothing circuit 20 through the positive line PL and the negative line NL. . The rectifier circuit 10 is, for example, a bridge-type full-wave rectifier circuit including six semiconductor diodes SD and having three sets of series-connected bodies of two semiconductor diodes SD forming upper and lower arms connected in parallel.

The smoothing circuit 20 suppresses and smoothes the pulsation of the DC power output from the rectifier circuit 10 and the DC power regenerated from the inverter circuit 30 .

The smoothing circuit 20 includes, for example, a smoothing capacitor 21 .

The smoothing capacitor 21 may be provided in a path connecting the positive line PL and the negative line NL in parallel with the rectifier circuit 10 and the inverter circuit 30 .

The smoothing capacitor 21 smoothes the DC power output from the rectifier circuit 10 and the DC power output (regenerated) from the inverter circuit 30 while repeating charging and discharging as appropriate.

The number of smoothing capacitors 21 may be one. A plurality of smoothing capacitors 21 may be arranged, and the plurality of smoothing capacitors 21 may be connected in parallel or in series between the positive line PL and the negative line NL. Also, the plurality of smoothing capacitors 21 may be configured such that two or more smoothing capacitors connected in series are connected in parallel between the positive line PL and the negative line NL.

Also, the smoothing circuit 20 may include, for example, a reactor.

The reactor may be provided, for example, on the positive line PL between the rectifier circuit 10 and the smoothing capacitor 21 (specifically, the branch point of the path where the smoothing capacitor 21 is arranged).

The reactor smoothes the DC power output from the rectifier circuit 10 and the DC power output (regenerated) from the inverter circuit 30 while appropriately generating a voltage so as to prevent a change in current.

The inverter circuit 30 has positive and negative input terminals connected to the other ends of the positive line PL and the negative line NL. The inverter circuit 30 converts the DC power supplied from the smoothing circuit 20 into three-phase AC power (for example, U-phase, V-phase, and W-phase) having a predetermined frequency and a predetermined voltage through switching operations of the semiconductor switches SW. It is converted and output to the electric motor EM. The semiconductor switch SW may be, for example, an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) made of silicon (Si). Also, the semiconductor switch SW may be a semiconductor element using a wide bandgap semiconductor such as silicon carbide (SiC) or gallium nitride (GaN).

The inverter circuit 30 includes, for example, six semiconductor switches SW, and three series-connected bodies (switch legs) of the two semiconductor switches SW forming upper and lower arms are connected in parallel between the positive line PL and the negative line NL. It is configured to include a bridge circuit. The inverter circuit 30 may output three-phase AC power through three output lines drawn from the connection points of the three sets of upper and lower arms. A free wheel diode may be connected in parallel to each of the six semiconductor switches SW.

The current sensor 40 detects the respective currents of the three-phase (three) output lines of the power conversion device 100, that is, the respective three-phase currents of the electric motor EM. The current sensor 40 outputs signals corresponding to current values of the three phases of the electric motor EM.

It should be noted that the current sensor 40 may detect only arbitrary two-phase currents among the three-phase output lines of the power converter 100 . In this case, the control circuit 70 may acquire (calculate) the remaining one-phase current value from the detected values of the two-phase currents. In addition, the control circuit 70 acquires the current values of the three-phase output lines of the power converter 100 based on, for example, the current values of the DC links (positive line PL and negative line NL) and the switching patterns of the semiconductor switches SW. (Calculation) may be performed. In this case, the control circuit 70 may acquire (calculate) the current value of the DC link based on the output of the voltage sensor 50 .

Voltage sensor 50 detects a voltage (DC link voltage) between positive line PL and negative line NL of power converter 100 . Voltage sensor 50 outputs a signal corresponding to the voltage value between positive line PL and negative line NL, and the output signal of voltage sensor 50 is taken into control circuit 70 .

Under the control of the control circuit 70, the gate drive circuit 60 outputs drive signals for switching (ON/OFF) the six semiconductor switches SW of the inverter circuit 30 to respective gate terminals of the six semiconductor switches SW.

A control circuit 70 (an example of a diagnostic device) controls the power conversion device 100 .

The functions of the control circuit 70 may be realized by arbitrary hardware or a combination of arbitrary hardware and software. For example, as shown in FIG. 1, the control circuit 70 is mainly a computer including an auxiliary storage device 71, a memory device 72, a CPU (Central Processing Unit) 73, and an interface device 74, which are connected to each other via a bus B1. configured to

The auxiliary storage device 71 is non-volatile storage means, and stores, for example, various installed programs and data necessary for various processes. The auxiliary storage device 71 is, for example, a flash memory.

The memory device 72 reads the program from the auxiliary storage device 71 and stores it in response to a program activation instruction. The memory device 72 is, for example, an SRAM (Static Random Access Memory).

The CPU 73 executes various programs loaded from the auxiliary storage device 71 to the memory device 72 and implements various functions related to the power converter 100 according to the programs. Accordingly, the control circuit 70 can perform various controls by loading the program installed in the auxiliary storage device 71 into the memory device 72 and causing the CPU 73 to execute the program.

The interface device 74 is used as an interface for communicably connecting to an external device of the control circuit 70 . The interface device 74 may have a plurality of types of interface devices depending on the communication method with the device to be connected. As a result, the control circuit 70 can receive data and signals from the outside and output (transmit) data and signals to the outside through the interface device 74 .

The control circuit 70 controls the inverter circuit 30, for example, so that the electric motor EM operates under predetermined operating conditions. Specifically, by outputting a control signal to the gate drive circuit 60, the control circuit 70 outputs a drive signal such as a PWM (Pulse Width Modulation) signal to the semiconductor switch SW via the gate drive circuit 60. and the inverter circuit 30 may be controlled.

Further, the control circuit 70 performs processing related to, for example, a diagnosis function of deterioration and life of the electric motor EM. Deterioration of the electric motor EM includes, for example, insulation deterioration such as layer shorts of coils. Details of the diagnostic function will be described later.

Note that the functions of the control circuit 70 may be implemented in a distributed manner by a plurality of control circuits mounted on the power converter 100 . For example, the control function of the inverter circuit 30 and the diagnostic function described above may be implemented by different control circuits. Also, part of the functions of the control circuit 70 may be transferred to the management device 200 or the terminal device 300 . For example, the diagnostic function described above may be transferred to the management device 200 and the terminal device 300 (both of which are examples of diagnostic devices). In this case, data necessary for the diagnostic function (eg, detection data of the current sensor 40, etc.) is transmitted (uploaded) to the management device 200 and the terminal device 300 through the communication section 90. FIG.

Under the control of the control circuit 70, the display unit 80 displays information about the power converter 100 to a user (for example, a worker in a factory where production equipment driven by the electric motor EM or mechanical equipment is installed). . The display unit 80 includes, for example, a warning light, an electronic bulletin board, a liquid crystal display, an organic EL (Electroluminescence) display, and the like.

The communication unit 90 communicates with an external device of the power conversion device 100 through a predetermined communication line.

The predetermined communication line may be, for example, a one-to-one communication line. Further, the predetermined communication line includes, for example, a local network (LAN: Local Area Network) such as a field network constructed in a facility (factory) where production equipment and mechanical equipment driven by the electric motor EM are installed. may be included. The local network may be constructed by wire, may be constructed by radio, or may include both. Further, the predetermined communication line may include, for example, a wide area network (WAN) outside a facility (factory) where production equipment driven by the electric motor EM and mechanical equipment are installed. The wide area network may include, for example, a mobile communication network with base stations as terminals, a satellite communication network using communication satellites, the Internet network, and the like. Further, the predetermined communication line may include, for example, a short-range communication line based on a predetermined wireless communication standard such as Bluetooth (registered trademark) or WiFi.

Note that the function of the communication unit 90 may be incorporated in the control circuit 70 as the function of the interface device 74 .

The management device 200 is provided outside the power conversion device 100 and manages (monitors) the power conversion device 100 and the electric motor EM as a host device of the power conversion device 100 .

The functions of the management device 200 are realized by arbitrary hardware or a combination of arbitrary hardware and software. For example, as shown in FIG. 2, the management device 200 includes an external interface 201, an auxiliary storage device 202, a memory device 203, a CPU 204, a communication interface 206, an input device 207, and a display device 208, which are connected to each other via a bus B2. include.

The external interface 201 functions as an interface for reading data from the recording medium 201A and writing data to the recording medium 201A. The recording medium 201A includes, for example, a flexible disk, a CD (Compact Disc), a DVD (Digital Versatile Disc), a BD (Blu-ray (registered trademark) Disc), an SD memory card, a USB memory, and the like. As a result, the management device 200 can read various data used in processing through the recording medium 201A, store the data in the auxiliary storage device 202, and install programs that implement various functions.

Note that the management device 200 may acquire various data and programs from an external computer through the communication interface 206 .

The auxiliary storage device 202 stores various installed programs, as well as files and data required for various processes. The auxiliary storage device 202 includes, for example, an HDD (Hard Disc Drive), SSD (Solid State Drive), flash memory, and the like.

The memory device 203 reads out and stores the program from the auxiliary storage device 202 when a program activation instruction is received. The memory device 203 includes, for example, a DRAM (Dynamic Random Access Memory) and an SRAM.

The CPU 204 executes various programs loaded from the auxiliary storage device 202 to the memory device 203, and implements various functions related to the management device 200 according to the programs.

The high-speed arithmetic device 205 works in conjunction with the CPU 204 and performs arithmetic processing at a relatively high speed. The high-speed arithmetic unit 205 includes, for example, a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), and the like.

Note that the high-speed arithmetic unit 205 may be omitted depending on the required arithmetic processing speed.

A communication interface 206 is used as an interface for communicably connecting to an external device. Thereby, the management device 200 can communicate with an external device such as the power conversion device 100 through the communication interface 206 . Also, the communication interface 206 may have a plurality of types of communication interfaces depending on the communication method with the connected device.

The input device 207 receives various inputs from the user. For example, the input device 207 includes an input device (operating device for remote control) for remote control by the operator.

The input device 207 includes, for example, an operation input device that receives mechanical operation input from the user. Operation input devices include, for example, buttons, toggles, levers, and the like. Further, the operation input device includes, for example, a touch panel mounted on the display device 208, a touch pad provided separately from the display device 208, and the like.

Also, the input device 207 includes, for example, a voice input device capable of accepting voice input from the user. The voice input device includes, for example, a microphone capable of collecting the user's voice.

Also, the input device 207 includes, for example, a gesture input device capable of accepting gesture input from the user. The gesture input device includes, for example, a camera capable of capturing an image of a user's gesture.

Also, the input device 207 includes, for example, a biometric input device capable of accepting biometric input from the user. A biometric input device includes, for example, a camera capable of acquiring image data containing information about a user's fingerprint or iris.

The display device 208 displays information screens and operation screens for the user. For example, display device 208 may include the remote display device described above. The display device 208 is, for example, a liquid crystal display, an organic EL display, or the like.

The management device 200, for example, acquires data on the states of the power converter 100 and the electric motor EM from the power converter 100, and monitors the states of the power converter 100 and the electric motor EM. Moreover, the management apparatus 200 outputs a control signal to the power converter device 100, for example, and controls the power converter device 100 and the electric motor EM. The management device 200 also provides information on the power conversion device 100 and the electric motor EM to users such as workers and administrators, receives input from the user, and transmits the information to the power conversion device 100 .

Moreover, as described above, the management device 200 may diagnose deterioration and life of the electric motor EM instead of the power conversion device 100 (control circuit 70).

The management device 200 is, for example, an edge controller such as a PLC (Programmable Logic Controller) that manages field devices including the power conversion device 100 in a factory or the like where machinery and production equipment driven by the electric motor EM are installed. Also, the management device 200 is, for example, a terminal device for management. The management terminal device may be, for example, a stationary computer terminal such as a desktop PC (Personal Computer) installed in an office such as a factory. In addition, the terminal device for management may be a portable terminal device (portable terminal) that can be carried by managers, workers, etc. of factories such as tablet terminals, smartphones, laptop PCs, etc. . Also, the management device 200 is, for example, a server device. The server device may be, for example, an on-premises server or a cloud server installed remotely, such as in a factory where production equipment or mechanical equipment driven by the electric motor EM is installed. Further, the server device may be an edge server installed in the premises of a factory or the like where production equipment or mechanical equipment electrically driven by the electric motor EM is installed, or in facilities in the vicinity thereof.

The terminal device 300 is a user terminal provided outside the power conversion device 100 and used by a user of the diagnostic system 1 . Users of the diagnostic system 1 are workers, administrators, and the like of factories in which production equipment and mechanical equipment driven by the electric motor EM are installed. The terminal device 300 , for example, provides the user with various types of information regarding the power electronics device 100 and the electric motor EM, accepts various inputs from the user, and transmits them to the power electronics device 100 .

The terminal device 300 may be, for example, a stationary terminal device such as a desktop PC. Also, the terminal device 300 may be, for example, a portable terminal device (mobile terminal) such as a smart phone, a tablet terminal, or a laptop PC.

[Function configuration related to diagnostic function]
Next, with reference to FIG. 3, a functional configuration relating to a diagnostic function of the power converter 100 (control circuit 70) will be described.

FIG. 3 is a functional block diagram showing an example of a functional configuration relating to the diagnostic function of the power converter 100 (control circuit 70).

As shown in FIG. 3, the control circuit 70 includes, as functional units related to diagnostic functions, a diagnostic information acquisition unit 701, a peak detection unit 702, a waveform counting unit 703, a feature amount acquisition unit 704, and an operating time acquisition unit. 705 , a diagnosis unit 706 and a notification unit 707 . The functions of the diagnostic information acquisition unit 701, the peak detection unit 702, the waveform counting unit 703, the feature amount acquisition unit 704, the operating time acquisition unit 705, the diagnosis unit 706, and the notification unit 707 are installed in the auxiliary storage device 71, for example. The program is loaded into the memory device 72 and executed by the CPU 73 .

The diagnostic information acquisition unit 701 acquires information (hereinafter referred to as “diagnostic information”) for diagnosing deterioration and life of the electric motor EM.

A diagnostic information acquisition unit 701 (an example of a first information acquisition unit) acquires information on an electrical physical quantity (hereinafter referred to as “diagnostic physical quantity”) representing the driving state of the electric motor EM as diagnostic information.

The information about the diagnostic physical quantity is, for example, information about the electric current of the electric motor EM. That is, the diagnostic physical quantity may be the electric current of the electric motor EM. Information about the current of the electric motor EM is obtained based on the output of the current sensor 40 . The information about the current of the electric motor EM is, for example, information about the phase current of the electric motor EM. The information about the electric current of the electric motor EM is, for example, information about two-phase alternating current (α-axis current and β-axis current) in the stationary coordinate system obtained by αβ conversion based on the three-phase phase current of the electric motor EM. There may be. Further, the information about the current of the electric motor EM is, for example, information about the two-phase alternating current (d-axis current and q-axis current) in the fixed coordinate system obtained by dq transformation based on the two-phase alternating current in the stationary coordinate system. may be

Also, the information about the diagnostic physical quantity may be, for example, information about the voltage of the electric motor EM. That is, the diagnostic physical quantity may be the voltage of the electric motor EM. Information about the voltage of the electric motor EM is acquired based on, for example, command values for the three-phase output voltages of the inverter circuit 30 generated by the control function of the control circuit 70 for the inverter circuit 30 . Further, the information about the voltage of the electric motor EM is acquired based on the detection information of the three-phase phase voltage and interphase voltage of the power converter 100, for example. In this case, the power conversion device 100 is equipped with a voltage sensor that detects the three-phase phase voltages and interphase voltages of the power conversion device 100 . The information about the voltage of the electric motor EM is, for example, information about the three phase voltages of the electric motor EM. The information about the voltage of the electric motor EM is, for example, information about the two-phase AC voltage (α-axis voltage and β-axis voltage) in the stationary coordinate system obtained by αβ conversion based on the three-phase phase voltage of the electric motor EM. There may be. Further, the information about the voltage of the electric motor EM is, for example, information about the two-phase AC voltage (d-axis voltage and q-axis voltage) in the fixed coordinate system obtained by dq conversion based on the two-phase AC voltage in the stationary coordinate system. may be

Also, the information about the diagnostic physical quantity may be information about the electric power of the electric motor EM, for example. That is, the diagnostic physical quantity may be the power of the electric motor EM. The information about the electric power of the electric motor EM is acquired based on the information about the current of the electric motor EM and the information about the voltage of the electric motor, for example. The information about the power of the electric motor EM is, for example, information about at least one of active power and reactive power of the electric motor EM.

In addition, the diagnostic information acquisition unit 701 (an example of a second information acquisition unit) acquires information on the rotation speed of the electric motor EM as diagnostic information in conjunction with (in synchronization with) acquisition of information on the diagnostic physical quantity. You may

Information about the rotation speed of the electric motor EM is acquired based on detection information of the rotation speed of the electric motor EM, for example. In this case, the electric motor EM is equipped with a sensor (for example, an encoder) or the like that detects the rotation speed of the electric motor EM. Further, the information about the rotation speed of the electric motor EM may be calculated (estimated) based on the output of the current sensor 40, that is, the detected value of the phase current of the electric motor EM.

Further, the diagnostic information acquisition unit 701 may correct the information related to the diagnostic physical quantity based on the rotation speed information, and acquire information related to the corrected diagnostic physical quantity (hereinafter, “corrected diagnostic physical quantity”). Specifically, the diagnostic information acquisition unit 701 corrects the diagnostic physical quantity information based on the rotation speed information so that the diagnostic physical quantity becomes a value corresponding to the reference rotation speed of the electric motor EM. Information about the corrected physical quantity may be obtained. This is because the diagnostic physical quantity changes according to the rotation state of the electric motor EM. Thereby, the control circuit 70 can suppress the influence of the rotation speed of the electric motor EM on the physical quantity for diagnosis, and as a result, the degree of deterioration of the electric motor EM can be diagnosed with higher accuracy. For example, the diagnostic information acquisition unit 701 corrects the information about the diagnostic physical quantity based on the rotation speed information using table data, maps, relational expressions, etc. that represent the correlation between the diagnostic physical quantity and the rotation speed of the electric motor EM. and information on the diagnostic correction physical quantity may be obtained. Table data, maps, relational expressions, and the like representing the correlation between the diagnostic physical quantity and the rotation speed of the electric motor EM may be defined in advance through, for example, experiments and simulations regarding the electric motor EM.

The peak detection unit 702 detects peaks, ie, peaks or troughs, of components corresponding to harmonics in time-series data (waveform data) of a diagnostic physical quantity or a diagnostic correction physical quantity for a predetermined period, and detects the value ( Hereafter, "peak value") Aj is detected. The subscript j represents the order of appearance of peak values in time series from the smallest. The peak detection unit 702, for example, applies various filters to the time-series data of the physical quantity for diagnosis or the correction physical quantity for diagnosis, removes the fundamental wave component, or removes a specific harmonic component (for example, the second harmonic component) may be extracted. As a result, the peak detection unit 702 can extract components corresponding to harmonics of time-series data of diagnostic physical quantities or diagnostic correction physical quantities. However, if the physical quantity for diagnosis or the correction physical quantity for diagnosis is a two-phase alternating current or voltage in a rotating coordinate system, the peak detection unit 702 detects the current (d-axis current and q-axis current) or voltage (d-axis voltage and q axis voltage) can be used as it is. Due to the dq transformation, the fundamental wave components of the phase currents and phase voltages become direct currents, and as a result, only the components corresponding to the distortion (harmonic components) appear as changes in the two-phase alternating currents and voltages in the rotating coordinate system. It is from. Specifically, the peak detection unit 702 monitors the time change of the component corresponding to the harmonic in the time-series data (waveform data) of the physical quantity for diagnosis or the correction physical quantity for diagnosis during a predetermined period. , or the value of the change point (trough) from descent to rise is detected as the peak value Aj.

A waveform counting unit 703 (an example of a cycle detecting unit) counts ( To detect. Cycles detected may include, for example, one cycle from peak to valley and back to peak, or from valley to peak and back to valley, plus half cycles of one half cycle. This is because, for example, the diagnostic physical quantity and the diagnostic correction physical quantity may change with time such that the mountain does not return to the original mountain level through the valley, or the diagnostic physical quantity and the diagnostic correction physical quantity do not return to the original valley level from the valley to the mountain. Hereinafter, a numerical value indicating whether the detected cycle is one cycle or a half cycle may be referred to as a "cycle value". The cycle value may be, for example, "1.0" for one cycle and "0.5" for half a cycle. The waveform counting unit 703 outputs a change width (hereinafter referred to as “cycle change value”) ΔAj of the diagnostic physical quantity or the diagnostic correction physical quantity in the detected cycle.

Specifically, the waveform counting unit 703 arbitrarily applies a known waveform coefficient method, and counts the cycle of change due to the components corresponding to harmonics in the time change of the physical quantity for diagnosis or the correction physical quantity for diagnosis. good. Applicable waveform counting methods include, for example, maximum-minimum method, maximum-minimum method, amplitude method, level crossing method, range pair method, rainflow method, three-point cycle counting method, and the like.

A feature amount acquisition unit 704 acquires a feature amount related to a change due to a component corresponding to a harmonic of a diagnostic physical quantity or a diagnostic correction physical quantity based on the time-series data of the cycle change value ΔAj output from the waveform counting unit 703. . The feature quantity acquisition unit 704 acquires, for example, a feature quantity that increases as the change due to components corresponding to harmonics of the diagnostic physical quantity or the diagnostic correction physical quantity increases. Thereby, the control circuit 70 (diagnostic unit 706) can diagnose the degree of deterioration of the electric motor EM so that the degree of deterioration of the electric motor EM increases as the feature amount increases, as will be described later.

Specifically, the feature amount may be a statistic obtained by statistical processing of the time-series data of the cycle change value ΔAj. The statistics relating to the time-series data of the cycle change values ΔAj are, for example, the mean value, median value, variance, standard deviation, etc. of the cycle change values ΔAj. Also, the statistic regarding the time-series data of the cycle change value ΔAj may be, for example, the number of occurrences or the frequency of occurrence of the cycle change value ΔAj equal to or greater than a predetermined reference. The predetermined reference may be, for example, the lower limit value of the cycle change value ΔAj that is assumed to cause an abnormality in the electric motor EM, and may be defined in advance through experiments and simulations regarding the electric motor EM. Also, the statistic related to the time-series data of the cycle change value ΔAj may be, for example, the value of an evaluation function whose argument is part or all of the time-series data of the cycle change value ΔAj.

The operating time acquisition unit 705 (an example of the operating time acquisition unit) acquires the cumulative operating time from the start of use of the electric motor EM at the time of acquisition of information on diagnostic physical quantities. The cumulative operating time of the electric motor EM means, for example, the cumulative operating time from the start of use of the electric motor EM in a new state after shipment from the factory. The cumulative operating time of the electric motor EM at the time of acquisition of the diagnostic physical quantity may be the cumulative operating time of the electric motor EM at the start of acquisition of the diagnostic physical quantity, or the cumulative operating time of the electric motor EM at the end of acquisition. It may be the cumulative operation time of the electric motor EM at intermediate times.

Specifically, the control circuit 70 may measure the operation time each time from the start of operation of the electric motor EM to the stop of the operation, and accumulatively record the measured operation time each time in the auxiliary storage device 71 or the like. As a result, the operating time acquisition unit 705 can acquire the cumulative operating time of the electric motor EM by accumulating the operating time each time from the start of use of the electric motor EM recorded in the auxiliary storage device 71 or the like.

The diagnosis unit 706 diagnoses the degree of progress of deterioration of the electric motor EM (hereinafter referred to as “deterioration degree”) based on the feature amount output from the feature amount acquisition unit 704 . Specifically, the diagnosis unit 706 may diagnose the degree of deterioration of the electric motor EM such that the degree of deterioration increases (higher) as the feature amount increases. The following description is based on the premise that the diagnosis unit 706 diagnoses the degree of deterioration in the range of 0% to 100%.

The diagnosis unit 706, for example, based on the feature amount output from the feature amount acquisition unit 704, uses a plurality of thresholds provided within the range of the feature amount corresponding to the degree of deterioration of 0% to 100% to determine the degree of deterioration of the electric motor EM. Diagnose the degree of deterioration. Specifically, different deterioration degree values may be specified for each of the plurality of threshold values in such a manner that the higher the threshold value, the higher the deterioration degree. A plurality of thresholds may be defined in advance through, for example, experiments or simulations regarding deterioration of the electric motor EM. As a result, when the feature quantity output from the feature quantity acquisition section 704 changes from below or below a certain threshold to above or above the threshold, the diagnosis unit 706 determines that the electric motor EM is at a degree of deterioration corresponding to the threshold. condition can be diagnosed. Therefore, the diagnosis unit 706 can diagnose the degree of deterioration of the electric motor EM so that the degree of deterioration increases stepwise in a relatively large range as the feature amount increases.

Further, the diagnosis unit 706 diagnoses the degree of deterioration of the electric motor EM based on, for example, the feature quantity output from the feature quantity acquisition unit 704 and using table data, a map, or the like representing the correlation between the feature quantity and the degree of deterioration. You may Table data, maps, and the like representing the correlation between the feature amount and the degree of deterioration may be set in advance through, for example, experiments, simulations, or the like regarding the deterioration of the electric motor EM. Thereby, the diagnosis unit 706 can diagnose the degree of deterioration of the electric motor EM so that the degree of deterioration increases stepwise in a relatively small range as the feature amount increases.

Further, the diagnosis unit 706 diagnoses the degree of deterioration of the electric motor EM, for example, based on the feature amount output from the feature amount acquisition unit 704, using an approximation expression representing the correlation between the feature amount and the degree of deterioration. good. The approximation expression representing the correlation between the feature quantity and the degree of deterioration may be set in advance through, for example, experiments or simulations regarding the deterioration of the electric motor EM. As a result, the diagnosis unit 706 can diagnose the degree of deterioration of the electric motor EM such that the degree of deterioration changes substantially continuously as the feature amount increases.

Incidentally, instead of using the information related to the above-described diagnostic correction physical quantity, on the premise of the diagnostic physical quantity, an approximation formula, table data, etc. representing the correlation between the above-described plurality of threshold values, the feature quantity, and the degree of deterioration are used. It may be corrected based on information about the rotational speed of the EM.

Further, the diagnosis unit 706 may diagnose the life of the electric motor EM based on the diagnosis result of the degree of deterioration of the electric motor EM and the accumulated operating time of the electric motor EM corresponding to the diagnosis result. Specifically, the diagnosis unit 706 may diagnose (estimate) the remaining life of the electric motor EM, that is, the remaining operable time. The cumulative operating time of the electric motor EM corresponding to the diagnosis result means the cumulative operating time of the electric motor EM at the time of acquisition of the physical quantity for diagnosis that is directly or indirectly used for the diagnosis through the correction physical quantity for diagnosis.

For example, the diagnosis unit 706 may estimate the remaining operable time of the electric motor EM based on the latest diagnosis result of the degree of deterioration of the electric motor EM and the cumulative operating time of the electric motor EM corresponding to the diagnosis result. Specifically, the diagnosis unit 706 uses the parameters of the table data and the approximation formula of the reference representing the correlation between the elapsed cumulative operating time of the electric motor EM and the progress of the degree of deterioration as the latest diagnosis result of the degree of deterioration of the electric motor EM. , and the accumulated operating time corresponding to the diagnostic result. Then, the diagnosis unit 706 acquires the cumulative operating time of the electric motor EM when the degree of deterioration of the electric motor EM becomes 100% based on the adjusted approximation formula and table data, and reduces the cumulative operating time corresponding to the diagnosis result. Thus, the remaining operable time of the electric motor EM may be estimated.

Further, for example, the diagnosis unit 706 estimates the remaining operable time of the electric motor EM using not only the latest diagnosis result of the deterioration degree of the electric motor EM but also the past diagnosis result of the deterioration degree of the electric motor EM. good too. That is, the diagnosis unit 706 estimates the remaining operable time of the electric motor EM based on the history of the diagnosis result of the degree of deterioration of the electric motor EM and the history of the accumulated operating time of the electric motor EM corresponding to the diagnosis result. good. Specifically, the diagnosis unit 706 calculates the degree of deterioration of the electric motor EM using a known extrapolation method based on the history of the diagnosis result of the degree of deterioration of the electric motor EM and the history of the accumulated operating time corresponding to the diagnosis result. The accumulated operating time of the electric motor EM when becomes 100% may be obtained. Then, the diagnosis unit 706 subtracts the accumulated operating time corresponding to the latest diagnosis result from the accumulated operating time of the electric motor EM when the degree of deterioration of the electric motor EM reaches 100%, thereby obtaining the remaining operable time of the electric motor EM. You can guess.

The notification unit 707 notifies the user of the diagnostic system 1 of the diagnosis result by the diagnosis unit 706 . This allows the user to grasp the degree of deterioration of the electric motor EM and the remaining operable time. Therefore, the user can make a plan for maintenance or replacement of the electric motor EM before a failure occurs in the electric motor EM. As a result, the control circuit 70 can perform maintenance according to the state of the electric motor EM, and reduce the risk of sudden stoppage of the equipment driven by the electric motor EM and long-term stoppage of the equipment accompanying restoration work. can do.

The notification unit 707 notifies the user of the diagnosis result of the diagnosis unit 706 by displaying the diagnosis result of the diagnosis unit 706 on the display unit 80, for example.

Also, the notification unit 707 may transmit the diagnosis result of the diagnosis unit 706 to the management device 200 and the terminal device 300 through the communication unit 90, for example. Thereby, the management device 200 can notify the user of the diagnosis result through the display device 208 or the like. Similarly, the terminal device 300 can notify the user of the diagnosis result through a display device or the like. That is, the notification unit 707 can notify the user of the diagnosis result by the diagnosis unit 706 through the management device 200 and the terminal device 300 .

[Concrete example when abnormality occurs due to motor deterioration]
Next, a specific example when an abnormality occurs due to deterioration of the electric motor EM will be described with reference to FIGS. 4 and 5. FIG.

FIG. 4 is a diagram showing an example of results of waveform counting processing and feature amount acquisition processing by the waveform counting unit 703 and feature amount acquiring unit 704. As shown in FIG. FIG. 5 is a diagram showing an example of the distribution of the number of occurrences of the cycle change value ΔAj when an abnormality occurs due to deterioration of the electric motor EM.

In FIG. 4, along the passage of time, from top to bottom, the cycle change value ΔAj of the cycle detected by the waveform counting unit 703, the cycle value, and the statistics of the time-series data of the cycle change value ΔAj (average, variance and median) are represented as time-series data. The statistic of the time-series data of the cycle change value ΔAj corresponds to the feature quantity acquired by the feature quantity acquisition unit 704 . The statistics of the time-series data of the cycle change values ΔAj are calculated based on the time-series data of the cycle change values ΔAj before the target cycle.

FIG. 5 shows the distribution of the number of occurrences of the cycle change value ΔAj corresponding to the results of the waveform counting process and the feature value acquisition process shown in FIG. The distribution of the number of occurrences of the cycle change value ΔAj after the occurrence of an abnormality is shown. Specifically, graph 501 represents the distribution of the number of occurrences of cycle change value ΔAj for time series data 401 in FIG. Represents the distribution of the number of times.

As shown in FIG. 4, in the range of time-series data 401 out of the entire time-series data 400, cycle change value ΔAj is relatively small, and electric motor EM is in a normal state. In this case, the statistics (average, variance, and median) of the time-series data of cycle change values ΔAj are relatively small values. On the other hand, within the range of the time series data 402 of the entire time series data 400, the cycle change value ΔAj is relatively large, and the electric motor EM is in an abnormal state due to deterioration. In this case, the statistics (average, variance, and median) of the time-series data of the cycle change values ΔAj are relatively large values. Therefore, the diagnosis unit 706 can diagnose the degree of deterioration of the electric motor EM based on the size of the statistic of the cycle change value ΔAj as the characteristic amount.

Further, as shown in FIG. 5, when an abnormality due to deterioration of the electric motor EM occurs, the number of occurrences of the cycle change value ΔAj in a relatively large range increases. Therefore, the diagnosis unit 706 can diagnose the degree of deterioration of the electric motor EM based on the number and frequency of occurrence of the cycle change value ΔAj equal to or greater than a predetermined reference (“12” or “14” in this example).

[Specific example of diagnosis processing]
Next, a specific example of diagnostic processing by the control circuit 70 will be described with reference to FIGS. 6 and 7. FIG.

FIG. 6 is a main flowchart schematically showing an example of diagnostic processing. FIG. 7 is a sub-flowchart schematically showing an example of diagnostic processing. Specifically, FIG. 7 is a sub-flowchart showing the details of the process of step S114 in FIG.

The main flowchart of FIG. 6 is automatically executed at predetermined timings, for example. The predetermined timing may be, for example, the start of operation after the power conversion device 100 and the electric motor EM are started. Further, the main flowchart of FIG. 6 is started, for example, when a predetermined input requesting diagnostic processing is received from the user. A predetermined input requesting diagnostic processing from the user may be received, for example, through a predetermined input unit provided in the power conversion device 100 . Further, a predetermined input requesting diagnostic processing from the user is accepted by the communication unit 90 receiving a signal representing a predetermined input by the user at the input device 207 of the management device 200 or the input device of the terminal device 300. may be

As shown in FIG. 6, in step S102, the diagnostic information acquisition unit 701 acquires time-series data for a predetermined period of the detected values of the three phase currents of the electric motor EM based on the output of the current sensor 40. FIG.

After completing the process of step S102, the control circuit 70 proceeds to step S104.

In step S104, the operating time acquisition unit 705 acquires the cumulative operating time of the electric motor EM at the time of acquiring the time-series data of the phase current detection values in step S102.

When the process of step S104 is completed, the control circuit 70 proceeds to step S106.

In step S106, the diagnostic information acquisition unit 701 acquires two-phase alternating current values (d-axis current value and q-axis voltage) for a predetermined period of time.

When the process of step S106 is completed, the control circuit 70 proceeds to step S108.

In step S108, the peak detection unit 702 detects a peak portion from the time-series data of the d-axis current value and the q-axis current value for a predetermined period, and detects the peak value Aj.

When the process of step S108 is completed, the control circuit 70 proceeds to step S110.

In step S110, the waveform counting unit 703 detects the cycle of time change of the d-axis current value or the q-axis current value, and obtains the cycle change value ΔAj.

When the process of step S110 is completed, the control circuit 70 proceeds to step S112.

In step S112, the feature amount acquisition unit 704 acquires a feature amount F related to the time change of the d-axis current value or the q-axis current value.

After completing the process of step S112, the control circuit 70 proceeds to step S114.

At step S114, the diagnosis unit 706 diagnoses the degree of deterioration of the electric motor EM based on the feature amount F obtained at step S112. For example, the degree of deterioration of the electric motor EM is diagnosed through the processing of the sub-flowchart of FIG.

As shown in FIG. 7, in step S1141, the diagnosis unit 706 determines whether or not the feature amount F is equal to or greater than the threshold value F1. The diagnosis unit 706 proceeds to step S1142 if the feature amount F is not equal to or greater than the threshold F1 (>0), and proceeds to step S1143 if the feature amount F is equal to or greater than the threshold F1.

At step S1142, the diagnosis unit 706 diagnoses that the electric motor EM has no deterioration, that is, the degree of deterioration is 0%.

When the process of step S1142 is completed, the control circuit 70 ends the process of the sub-flowchart.

On the other hand, in step S1143, the diagnosis unit 706 determines whether or not the feature amount F is a threshold value F2 (>F1). The diagnosis unit 706 proceeds to step S1144 if the feature amount F is not equal to or greater than the threshold F2, and proceeds to step S1145 if the feature amount F is equal to or greater than the threshold F2.

In step S1144, diagnosis unit 706 diagnoses that the degree of deterioration of electric motor EM is X1[%] (>0%).

When the process of step S1144 is completed, the control circuit 70 ends the process of the current sub-flowchart.

On the other hand, in step S1145, the diagnosis unit 706 determines whether or not the feature amount F is equal to or greater than the threshold value F3 (>F2). The diagnosis unit 706 proceeds to step S1146 if the feature amount F is not equal to or greater than the threshold F3, and proceeds to step S1147 if the feature amount F is equal to or greater than the threshold F3.

In step S1146, diagnosis unit 706 diagnoses that the degree of deterioration of electric motor EM is X2[%] (>X1[%]).

When the process of step S1146 is completed, the control circuit 70 ends the process of the current sub-flowchart.

On the other hand, in step S1147, diagnosis unit 706 diagnoses that the degree of deterioration of electric motor EM is 100% (>X2[%]).

When the process of step S1147 is completed, the control circuit 70 ends the process of this flowchart.

Returning to FIG. 6, when the process of step S114 is completed, the control circuit 70 proceeds to step S116.

In step S116, the diagnosis unit 706 diagnoses the life of the electric motor EM based on the diagnosis result of the degree of deterioration of the electric motor EM and the accumulated operating time acquired in step S104.

Note that the process of step S116 may be omitted.

When the process of step S116 is completed, the control circuit 70 proceeds to step S118.

In step S118, the notification unit 707 notifies the user of the diagnosis results in steps S114 and S116 through the display unit 80, the management device 200, the terminal device 300, and the like.

When the process of step S118 is completed, the control circuit 70 ends the process of the main flowchart.

[Action]
Next, the operation of the power conversion device 100 (control circuit 70) according to this embodiment will be described.

In this embodiment, the power conversion device 100 (control circuit 70) includes a diagnostic information acquisition section 701, a feature amount acquisition section 704, and a diagnosis section 706. FIG. Specifically, the diagnostic information acquisition unit 701 acquires information about an electrical physical quantity (diagnostic physical quantity) representing the driving state of the electric motor EM. In addition, the feature amount acquisition unit 704 acquires feature amounts related to temporal changes in electrical physical quantities. Then, the diagnosis unit 706 diagnoses the degree of deterioration (degree of deterioration) of the electric motor EM based on the feature amount.

As a result, the control circuit 70 can detect the degree of deterioration (progress of deterioration) leading to failure of the electric motor EM before the electric motor EM fails and equipment driven by the electric motor EM suddenly stops. User can be notified. Therefore, the control circuit 70 can appropriately prompt the user to formulate and execute a maintenance plan according to the state of the electric motor EM, and as a result, it is possible to reduce the frequency of maintenance of equipment including the electric motor EM. In addition, the control circuit 70 can reduce risks such as sudden stoppage of the equipment including the electric motor EM and long-term stoppage of the equipment accompanying restoration work.

Further, for example, it is possible to diagnose the deterioration of the electric motor EM by focusing on the frequency component of the electric physical quantity of the electric motor EM. is required. As a result, the spectrum analysis or the like increases the processing load for diagnosing an abnormality, which puts pressure on the resources of the control circuit 70. In order to suppress the pressure on the resources of the control circuit 70, an expensive measuring device is required. An introduction may be required.

On the other hand, in the present embodiment, the processing load for diagnosing the electric motor EM can be reduced by using the feature amount related to the temporal change of the electric physical quantity of the electric motor EM.

Further, in the present embodiment, the diagnosis unit 706 may diagnose the degree of progress of deterioration of the electric motor EM so that the degree of progress of deterioration increases as the feature amount increases.

Thereby, the control circuit 70 can specifically diagnose the degree of progress of deterioration of the electric motor EM in accordance with an increase in the feature amount.

Also, in this embodiment, a plurality of thresholds may be provided. Then, the diagnosing unit 706 may diagnose the degree of progression of deterioration so that the degree of progression of deterioration increases each time the feature value exceeds one of the plurality of thresholds, starting with the smallest threshold.

Thereby, the control circuit 70 can specifically diagnose the degree of progress of deterioration of the electric motor EM in accordance with an increase in the feature amount.

Further, in this embodiment, the control circuit 70 may include a peak detector 702 and a waveform counter 703 . Specifically, the peak detection unit 702 may detect a peak in temporal change of an electrical physical quantity representing the drive state of the electric motor EM. Further, the waveform counting unit 703 may detect the cycle of time change of the electrical physical quantity representing the driving state of the electric motor EM based on the history of the peak values (peak value Aj) detected by the peak detecting unit 702. . Then, the feature amount acquisition unit 704 acquires the feature amount based on the history of the change width (cycle change value ΔAj) of the electrical physical quantity representing the driving state of the electric motor EM in the cycle detected by the waveform counting unit 703. good too.

Thereby, the control circuit 70 can specifically acquire the feature amount.

Further, in the present embodiment, the control circuit 70 may include an operating time acquisition section 705 . Specifically, the operating time acquisition unit 705 may acquire the operating time from the start of use of the electric motor EM. Then, the diagnosis unit 706 may diagnose the life of the electric motor EM based on the diagnosis result of the degree of progress of deterioration and the operation time of the electric motor EM corresponding to the diagnosis result.

Thereby, the control circuit 70 can notify the user of the remaining life (remaining operable time) of the electric motor EM in addition to the degree of deterioration of the electric motor EM. Therefore, the control circuit 70 can more appropriately prompt the user to formulate and execute a maintenance plan according to the state of the electric motor EM.

Further, in the present embodiment, the diagnosis unit 706 may diagnose the life of the electric motor EM based on the history of the diagnosis result of the degree of deterioration and the history of the operation time of the electric motor EM corresponding to the history of the diagnosis result. good.

This allows the control circuit 70 to more accurately estimate the remaining life (remaining operable time) of the electric motor EM.

Further, in the present embodiment, the electrical physical quantity representing the drive state of the electric motor EM may be the electric current, voltage, or power of the electric motor EM.

As a result, the control circuit 70 can detect the time change of the current, voltage, or power of the electric motor EM, and specifically diagnose the deterioration of the electric motor EM.

Further, in the present embodiment, the diagnostic information acquisition unit 701 may acquire information regarding the rotation speed of the electric motor EM. Then, the diagnosis unit 706 may diagnose the degree of progress of deterioration of the electric motor EM based on the information regarding the rotation speed.

Thus, the control circuit 70 can diagnose the degree of progress of deterioration of the electric motor EM by taking into account changes in the electric physical quantity representing the driving state of the electric motor EM due to the rotational state (rotational speed) of the electric motor EM. Therefore, the control circuit 70 can more accurately diagnose the progress of deterioration of the electric motor EM.

Although the embodiments have been described in detail above, the present disclosure is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the claims.

Reference Signs List 1 diagnostic system 10 rectifier circuit 20 smoothing circuit 21 smoothing capacitor 30 inverter circuit 40 current sensor 50 voltage sensor 60 gate drive circuit 70 control circuit 71 auxiliary storage device 72 memory device 73 CPU
74 interface device 80 display unit 90 communication unit 100 power conversion device 200 management device 201 external interface 201A recording medium 202 auxiliary storage device 203 memory device 204 CPU
205 high-speed arithmetic unit 206 communication interface 207 input device 208 display device 300 terminal device 701 diagnostic information acquisition unit 702 peak detection unit 703 waveform counting unit 704 feature amount acquisition unit 705 operating time acquisition unit 706 diagnosis unit 707 notification unit B1 bus B2 bus EM Electric motor NL Negative line PL Positive line PS Commercial power supply SD Semiconductor diode SW Semiconductor switch

Claims (11)

a first information acquisition unit that acquires information about an electrical physical quantity representing the drive state of the AC motor;
a feature quantity acquisition unit that acquires a feature quantity related to the time change of the electrical physical quantity;
a diagnostic unit that diagnoses the degree of progress of deterioration of the AC motor based on the feature amount;
diagnostic equipment. The diagnosis unit diagnoses the degree of progression of the deterioration so that the degree of progression of the deterioration increases as the feature amount increases.
A diagnostic device according to claim 1 . Multiple thresholds are set,
The diagnosis unit diagnoses the degree of progression of the deterioration so that the degree of progression of the deterioration increases each time the feature amount exceeds the threshold, starting from the smaller one of the plurality of thresholds.
A diagnostic device according to claim 2. a peak detection unit that detects a peak in the time change of the electrical physical quantity;
a cycle detection unit that detects a cycle of time change of the electrical physical quantity based on a history of peak values detected by the peak detection unit;
The feature amount acquisition unit acquires the feature amount based on a history of the change width of the electrical physical quantity in the cycle detected by the cycle detection unit.
4. A diagnostic device according to any one of claims 1-3. An operating time acquisition unit that acquires an operating time from the start of use of the AC motor,
The diagnosis unit diagnoses the life of the AC motor based on the diagnosis result of the degree of progress of deterioration and the operation time of the AC motor corresponding to the diagnosis result.
5. A diagnostic device according to any one of claims 1-4. The diagnosis unit diagnoses the life of the AC motor based on a history of diagnosis results of the degree of progress of deterioration and a history of the operation time of the AC motor corresponding to the history of the diagnosis results.
A diagnostic device according to claim 5 . the electrical physical quantity is the current, voltage, or power of the AC motor;
7. A diagnostic device according to any one of claims 1-6. A second information acquisition unit that acquires information about the rotation speed of the AC motor,
The diagnosis unit diagnoses the degree of progress of the deterioration of the AC motor based on the information about the rotation speed.
A diagnostic device according to any one of the preceding claims. A power conversion device that supplies driving power to the AC motor based on power input from the outside,
A diagnostic device according to any one of claims 1 to 8,
Power converter. a first information acquisition step in which the diagnostic device acquires information about an electrical physical quantity representing the driving state of the AC motor;
a feature quantity acquiring step in which the diagnostic device acquires a feature quantity relating to the time change of the electrical physical quantity;
a diagnostic step in which the diagnostic device diagnoses the degree of progress of deterioration of the AC motor based on the feature quantity;
diagnostic method. diagnostic equipment,
a first information obtaining step of obtaining information about an electrical physical quantity representing the drive state of the AC motor;
a feature amount obtaining step of obtaining a feature amount related to the time change of the electrical physical quantity;
a diagnostic step of diagnosing the degree of progress of deterioration of the AC motor based on the feature quantity;
program.

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