Control device, electrical device, and control method of electrical device

Abstract

To realize a stable operation of an electrical device.SOLUTION: A control device according to an embodiment includes a failure detection unit configured to detect a failure. The failure detection unit is configured to perform frequency analysis on an electrical signal for driving an electric motor, calculate a phase of the electrical signal, calculate a phase difference between a phase of a fundamental wave of a power supply frequency of the electrical signal and the calculated phase of the electrical signal, extract a first signal indicating an outflow component from the electric motor based on a calculation result of the phase difference, extract a second signal indicating an inflow component to the electric motor based on the calculation result of the phase difference, and detect the failure based on the first signal.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a control device, an electric device, and a method for controlling an electric device. [Background technology]

[0002] An apparatus for detecting motor faults is incorporated into equipment that includes an electric motor powered by an AC power source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6585979 specification [Patent Document 2] Patent No. 3823248 specification [Patent Document 3] Special Publication No. 2023-542056 Summary of the Invention [Problem to be solved by the invention]

[0004] Ensure stable operation of electrical equipment. [Means for solving the problem]

[0005] The control device of the embodiment includes a control unit that controls an electric motor, and a fault detection unit that detects a fault in the electric motor, wherein the fault detection unit performs frequency analysis on an electric signal that drives the electric motor, calculates the phase of the electric signal, calculates the phase difference between the phase of the fundamental wave of the power supply frequency of the electric signal and the calculated phase of the electric signal, extracts a first signal that indicates an outflow component from the electric motor based on the calculation result of the phase difference, extracts a second signal that indicates an inflow component to the electric motor based on the calculation result of the phase difference, and detects the fault based on the first signal. [Brief explanation of the drawings]

[0006] [Figure 1]1 is a circuit diagram showing an example of the configuration of an electric device including a control device according to a first embodiment. [Figure 2] FIG. 2 is a block diagram showing an example of the configuration of a failure detection unit in the control device of the first embodiment. [Figure 3] FIG. 4 is a diagram showing experimental results regarding the control device of the first embodiment. [Figure 4] FIG. 4 is a diagram showing experimental results regarding the control device of the first embodiment. [Figure 5] 4 is a flowchart showing an example of the operation of the control device of the first embodiment. [Figure 6] FIG. 10 is a diagram showing an example of the configuration of an electrical device including a control device according to a second embodiment. [Figure 7] FIG. 10 is a diagram showing experimental results regarding the control device of the second embodiment. [Figure 8] FIG. 10 is a diagram showing experimental results regarding the control device of the second embodiment. [Figure 9] FIG. 10 is a diagram showing an example of the configuration of an electrical device including a control device according to a third embodiment. [Figure 10] FIG. 10 is a diagram showing a modified example of the control device of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] 1 to 10, a control device, an electrical device, and a control method for an electrical device according to an embodiment will be described. In the following description, elements having the same function and configuration will be given the same reference numerals. Furthermore, in each of the following embodiments, when components (e.g., circuits, wiring, various voltages and signals, etc.) are given reference numerals with distinguishing numbers / letters at the end, and do not need to be distinguished from one another, the reference numerals will be omitted.

[0008] (Embodiment) (1) First embodiment A control device and an electric device according to a first embodiment will be described with reference to FIGS.

[0009] (a) Configuration example An example of the configuration of the control device and electrical equipment of this embodiment will be described with reference to FIGS.

[0010] Fig. 1 is a circuit diagram showing an example of the configuration of an electric device 1 including a control device 30 of this embodiment. In Fig. 1, the electric device 1 of this embodiment has a configuration for controlling a three-phase induction motor using a three-phase AC power supply.

[0011] As shown in FIG. 1, the electrical device 1 of this embodiment includes an AC power supply 10, a motor (electric motor) 11, a switch (breaker circuit) 15, a voltage sensor circuit 20, a voltage detection circuit 21, a current sensor circuit 22, a current detection circuit 23, and a control device 30.

[0012] The AC power supply 10 is connected to the motor 11 via a three-phase wiring. The AC power supply 10 supplies a three-phase AC voltage (and AC current) including a U phase, a V phase, and a W phase to the motor 11. The AC power supply 10 may be an external component of the electric device 1.

[0013] The motor 11 is driven by an electrical signal from the AC power supply 10. The motor 11 is driven by receiving voltages (and currents) of U-phase, V-phase, and W-phase via a three-phase connection. The motor 11 generates mechanical energy by the AC voltage from the AC power supply 10. For example, the output shaft of the motor 11 is connected to a load device (not shown) and a drive device (not shown).

[0014] The switch 15 is provided between the AC power supply 10 and the motor 11. The switch 15 controls the supply of voltage from the AC power supply 10 to the motor 11 under the control of the control device 30. For example, if a failure of the motor 11 is detected, the switch 15 cuts off the supply of voltage from the AC power supply 10 to the motor 11.

[0015] The voltage sensor circuit 20 is connected to the three-phase wiring. The voltage sensor circuit 20 senses the voltage supplied to the wiring of each phase that forms the three-phase wiring. The voltage sensor circuit 20 includes a voltage sensor such as a volt transformer (VT) to detect the voltage of each phase.

[0016] The voltage detection circuit 21 is connected to the voltage sensor circuit 20. The voltage detection circuit 21 receives a voltage signal corresponding to the sensed result of the voltage of each phase by the voltage sensor circuit 20. The voltage detection circuit 21 detects the state of the voltage of each phase of the three-phase connection based on the sensed result of the voltage sensor circuit 20. The voltage detection circuit 21 has a function of converting the voltage signal from the voltage sensor circuit 20 into a signal corresponding to the input voltage of an ADC 310 of the control device 30, which will be described later.

[0017] The current sensor circuit 22 is connected to the three-phase wiring. The current sensor circuit 22 senses the current (phase current) flowing through the wiring of each phase that forms the three-phase wiring. The current sensor circuit 22 includes a current sensor such as a current transformer (CT) to detect the phase current.

[0018] The current detection circuit 23 is connected to the current sensor circuit 22. The current detection circuit 23 receives a current signal corresponding to the result of sensing the current of each phase by the current sensor circuit 22. The current detection circuit 23 detects the state of the current of each phase of the three-phase connection based on the sensed result of the current sensor circuit 22. The current detection circuit 23 has a function of performing voltage conversion or impedance matching in order to apply the current signal from the current sensor circuit 22 to the input of the ADC 310, which will be described later.

[0019] The control device 30 controls the internal operation of the electric device 1. In the electric device 1 of this embodiment, the control device 30 includes an ADC (analog-digital converter) 310, a fault detection unit 320, a control unit 330, and the like.

[0020] The ADC 310 converts into digital signals (digital values) various analog signals (analog values) detected in the electric device 1. For example, the ADC 310 converts into digital signals the signals from the voltage detection circuit 21 and the current detection circuit 23.

[0021] The failure detection unit (also called a failure detection circuit) 320 detects a malfunction of the electric device 1, such as a malfunction of the motor 11 or a fault in the AC power supply 10, based on various signals detected in the electric device 1.

[0022] The control unit (also called a control circuit) 330 monitors the operating state of each component in the electric device 1 and controls the operation of each component. The control unit 330 can control the function and processing of the failure detection unit 320. The control unit 330 is, for example, a processor.

[0023] The control device 30 may further include a memory 390. The memory 390 stores various types of data. For example, the memory 390 can store data of the voltage and current sensing results (e.g., data of electrical signals) and programs (software and applications) for controlling the electric motor.

[0024] The electric device 1 of this embodiment is driven by a three-phase AC power supply 10. The electric device 1 controls the rotation of the motor 11 by a control device 30 while sensing the voltage and current values ​​generated by the three-phase AC power supply 10.

[0025] For example, if a fault such as an overcurrent, a short circuit, or a ground fault occurs in the motor 11, the electrical device 1 shuts off the AC power supply 10 using the switch 15 based on an instruction from the control device 30. For example, if an abnormality such as an open phase, an imbalance, a dip, or a swell occurs in the AC power supply 10, the electrical device 1 protects the motor 11 by shutting off the switch 15 based on an instruction from the control device 30.

[0026] The electric device 1 of this embodiment communicates with a higher-level device 9 such as a PLC (Programmable Logic Controller). The higher-level device 9 communicates with the control devices 30 of a plurality of electric devices 1. The higher-level device 9 monitors the operating status of the electric device 1 based on the results of the communication. For example, the higher-level device 9 periodically monitors the power consumption and a status signal obtained in real time from the fault detection unit 320. In this way, the higher-level device 9 grasps the status of the motor 11 in the electric device 1 and the status of the load device (not shown).

[0027] In this embodiment, the control device 30 detects a fault on the motor 11 side and a fault on the power supply 10 side through analysis processing by the fault detection unit 320.

[0028] Fig. 2 shows an example of the configuration of the fault detection unit 320 of the control device 30 in the electric device 1 of this embodiment. Note that Fig. 2 shows an example of the configuration of a signal calculator for electric signals (voltage signal and current signal) of one phase of a three-phase system. Substantially the same calculations are performed for the current signals (current values) and voltage signals (voltage values) of the other phases.

[0029] The fault detection unit 320 performs various types of arithmetic processing. The arithmetic processing by the fault detection unit 320 includes frequency analysis of the electric signal between the AC power supply 10 and the motor 11. The fault detection unit 320 has various configurations (functional blocks) for distinguishing information about the phase of the electric signal in order to detect the phase difference of the detected electric signal.

[0030] The failure detection unit 320 includes one or more arithmetic units (processors) configured by a microcomputer unit (MCU) or an application specific integrated circuit (ASIC) in the control device 30. The failure detection unit 320 can use data and programs in the memory 390.

[0031] As shown in FIG. 2, the fault detection unit 320 includes an LPF (low pass filter) 321, an FFT (fast Fourier transform) calculator 322, a phase angle calculator 323, an amplitude calculator 324, a comparison classifier 325, an in-phase signal analyzer 326, and an anti-phase signal analyzer 327.

[0032] The voltage detection circuit 21 and the current detection circuit 23 are connected to the control device 30. The voltage detection circuit 21 detects a voltage signal (analog signal) based on the sense result of the voltage sensor circuit 20. The voltage detection circuit 21 sends a voltage signal corresponding to the detection result to the ADC 310 of the control device 30. The current detection circuit 23 detects a current signal (analog signal) based on the sense result of the current sensor circuit 22. The current detection circuit 23 sends a current signal corresponding to the detection result to the ADC 310 of the control device 30.

[0033] In the control device 30, the ADC 310 performs analog-to-digital conversion (AD conversion) on the signal from the voltage detection circuit 21 and the signal from the current detection circuit 23. The ADC 310 sends the digital signal obtained by the AD conversion to the LPF 321 in the failure detection unit 320.

[0034] The LPF 321 passes signals having frequencies equal to or lower than the cutoff frequency of the digital signal from the ADC 310. The LPF 321 sends the filtered signal (LPF-processed signal) to the FFT calculator 322. The LPF 321 performs LPF processing to limit the band of the digital signal to a signal band for monitoring the state of the motor 11 (the state of the electrical device 1). This enables the fault detection unit 320 to block, for example, harmonic noise and disturbance noise contained in the signal resulting from the power supply 10 in the electrical signal indicating the detection results of the current and voltage.

[0035] It should be noted that the filtering process for the digital signal from the ADC 310 may employ LPF processing as decimation filtering (averaging and thinning) in order to improve the signal-to-noise ratio of the signal.

[0036] The FFT calculator 322 performs an FFT on the signal from the LPF 321. The FFT is a signal processing method that performs a Fourier transform at high speed. The FFT calculator 322 performs a fast Fourier transform on the signal from the LPF 321. This results in a complex function of the electrical signal. The FFT calculator 322 sends a signal indicating the result of the FFT to the phase angle calculator 323 and the amplitude calculator 324. The FFT result from the FFT calculator 322 is separated into information on the phase angle component of the electrical signal and information on the amplitude component, which are extracted. The FFT calculator 322 sends information on the phase angle based on the result of the FFT to the phase angle calculator 323. The FFT calculator 322 supplies information on the amplitude component based on the result of the FFT to the amplitude calculator 324.

[0037] The computational load in processing by FFT calculator 322 varies depending on the number of input samples. Because the signal band of an induction motor is up to around 1 kHz, FFT calculator 322 often performs computations using a sample count of 1024 to 2048 points. Note that in order to clearly capture the peaks of sideband waves that occur due to deterioration of the bearings of motor 11, the number of samples in the FFT computation and the signal band may be adjusted to set the frequency resolution to 1 Hz or less.

[0038] The FFT calculator 322 can be implemented by software or by a hardware accelerator.

[0039] The phase angle calculator 323 calculates the phase angle (phase) of the electrical signal and sends the calculated phase angle to the comparison classifier 325.

[0040] The amplitude calculator 324 calculates the amplitude of the electrical signal and sends the calculated amplitude to the comparison classifier 325.

[0041] The comparison classifier 325 receives the phase angle calculation result from the phase angle calculator 323 and the amplitude calculation result from the amplitude calculator 324. The comparison classifier 325 compares the phase angle of the fundamental wave of the power supply frequency of the electrical signal (hereinafter simply referred to as the fundamental wave) with the phase angle of each electrical signal. The comparison classifier 325 classifies the multiple electrical signals according to the magnitude of the compared phase angles. The comparison classifier 325 compares the amplitude of the fundamental wave of the power supply frequency of the electrical signal with the amplitude of each electrical signal. The comparison classifier 325 classifies the multiple electrical signals according to the magnitude of the compared amplitudes.

[0042] Based on the information on the phase angle component of the FFT calculation result, the comparison classifier 325 classifies the signals into in-phase signals (also called inflow signals) that have a phase difference that is the same as the phase of the fundamental wave of the electrical signal corresponding to the power supply frequency, and anti-phase signals (also called outflow signals) that have a phase difference that is the opposite phase to the phase of the fundamental wave of the electrical signal corresponding to the power supply frequency. Based on the classification result of the electrical signals according to the magnitude of the phase difference, the comparison classifier 325 sends the classified signals to the in-phase signal analyzer 326 and the anti-phase signal analyzer 327, respectively.

[0043] For example, the comparison classifier 325 calculates and compares the phase difference between the phase of the fundamental wave of the voltage signal and the phase of the current signal (or voltage signal) using the phase of the fundamental wave of the voltage signal at the power supply frequency as a reference, and classifies the electrical signal based on the comparison result.

[0044] Based on the classification result of the comparison classifier 325, the in-phase signal analyzer 326 analyzes the electrical signal (inflow signal, in-phase signal) having the same phase as the phase of the fundamental wave of the electrical signal (here, voltage signal).

[0045] The incoming signal is a signal (frequency component) having a phase difference of less than ±90 degrees. More specifically, the incoming signal is a signal having a phase difference within the range of 0 degrees to 360 degrees, with respect to the phase of the fundamental wave, within the range of 0 degrees to +90 degrees and within the range of 0 degrees to -90 degrees. The incoming signal is a signal that indicates the incoming component to the motor 11. The incoming component (frequency component) is a component that represents the characteristics of the electrical signal of the power source 10, and a change in the incoming component in the incoming signal represents a change in the state of the power source 10. In other words, the incoming signal is a signal that originates from the power source 10.

[0046] Based on the classification result of the comparison classifier 325, the antiphase signal analyzer 327 analyzes an electrical signal (outflow signal, antiphase signal) having an antiphase to the electrical signal (here, voltage signal).

[0047] The outflow signal is a signal (frequency component) having a phase difference of ±90 degrees or more and 180 degrees or less. More specifically, the outflow signal is a signal having a phase difference of +90 degrees to +180 degrees and -90 degrees to -180 degrees relative to the phase of the fundamental wave, within a phase difference range of 0 degrees to 360 degrees. The outflow signal is a signal indicating the outflow component from the motor 11. The outflow component (frequency component) is, for example, a component generated by changes in the mutual inductance of the rotor of the motor 11 and is generated by mechanical vibration. If vibration increases due to deterioration of components of the motor 11, such as bearings, the outflow component signal increases. In other words, the outflow signal is a signal originating from the motor 11 and can be used to monitor the fault state of the motor 11.

[0048] The in-phase signal analyzer 326 generates a control signal based on the analysis result of the inflow signal. The anti-phase signal analyzer 327 generates a control signal based on the analysis result of the outflow signal. For example, the control unit 330 controls the operation of the motor 11 and the electric device 1 based on the control signal from the in-phase signal analyzer 326 and the control signal from the anti-phase signal analyzer 327. The fault detection unit 320 may directly control the operation of the motor 11 and the electric device 1 using the control signal based on the analysis result.

[0049] The electric device 1 of this embodiment can grasp the fault state of the motor 11 by analyzing the outflow signal by the fault detection unit 320. The electric device 1 of this embodiment can grasp the fault state of the AC power supply 10 (and the system) by analyzing the inflow signal by the fault detection unit 320.

[0050] The failure detection unit 320 may have a computing unit independent of the control device 30 as a circuit or device including the above-described functions of the failure detection unit 320. This allows the failure detection unit 320 to execute various types of computational processing for detecting a failure of the electric device 1, independent of the normal control of the electric device 1 by the control device 30.

[0051] (b) Experiments and verification 3 and 4, the results of an experiment on failure detection by the failure detection unit 320 in the electric device 1 of this embodiment will be described.

[0052] Fig. 3 is a graph showing experimental results of the electric device 1 of this embodiment. Fig. 3 shows an example of an experiment in which an experiment was conducted in which a failure of a bearing of an induction motor was accelerated, and an example in which an inflow signal and an outflow signal were compared in frequency analysis.

[0053] Figure 3(a) shows the motor current spectrum in the early stage of bearing deterioration of an induction motor. In Figure 3(a), the horizontal axis of the graph corresponds to frequency, and the vertical axis of the graph corresponds to signal magnitude.

[0054] 3(a), for the electrical signal shown in the motor current spectrum, the 50 Hz peak 90 is the fundamental wave. Note that the second and higher harmonic peaks of the fundamental wave 90 are not outflow components.

[0055] Here, we assume that the phase difference of the phase current with respect to the power supply voltage is small. Based on this assumption, the inflow component (inflow signal) and outflow component (outflow signal) are distinguished based on the phase difference of the current signal with respect to the fundamental wave (50 Hz) of the power supply voltage (voltage signal).

[0056] As shown in (a) of Figure 3, in the waveform of the electrical signal in the initial state of deterioration (when the motor 11 is in a substantially normal state), the phase change of the harmonic component 99 of the power supply is small relative to the 50 Hz fundamental wave 90 in the voltage signal, and it can be seen that it is the same phase component as the fundamental wave.

[0057] The dotted plots in Figure 3(a) (and (b)) show outflow component signals (outflow signals). In addition to harmonics of the power supply frequency, outflow signals represent signals corresponding to mechanical vibrations and signals that have become antiphase components due to inductive fluctuations for other reasons. In the initial state of deterioration of the electrical equipment 1, most of the outflow component signals are signals equivalent to noise.

[0058] Figure 3(b) shows the motor current spectrum in the final stage of deterioration of the induction motor bearings. In Figure 3(b), the horizontal axis of the graph corresponds to frequency, and the vertical axis of the graph corresponds to signal magnitude.

[0059] In FIG. 3(b), a sideband 95 appears at a portion shifted by the rotation frequency (here, 25 Hz) from the fundamental wave 90 of the voltage signal.

[0060] Of the harmonic components 99 of the power supply frequency, the third harmonic component 99a is modulated by vibration and becomes an outflow component.

[0061] Generally, the final stage of deterioration is when the deterioration of the bearings in the induction motor has progressed to the point where the motor needs to be replaced.

[0062] The sideband wave 95 component, which is a mechanical fault signal caused by bearing vibration, is detected as an outflow signal. In motor current spectrum analysis, it is usually determined that the induction motor is in a fault state when the difference in peak level of the sideband wave 95 is 40 dB or less.

[0063] In FIG. 3(b), the peak level of the sideband wave 95 in the initial state and periodic state of the electrical device 1 differs by approximately 20 dB to 30 dB from the peak level of the fundamental wave 90 of the power supply frequency, which indicates that the bearings of the induction motor are deteriorating.

[0064] In the electric device 1 of this embodiment, the failure detection unit 320 uses the increase in the peak value of this sideband wave 95 as a guideline to monitor the failure state of the bearings of the motor 11.

[0065] In this embodiment, it can be estimated that even in the harmonic component 99 of the power supply frequency, the third harmonic component 99a becomes an outflow component, and due to electromagnetic influence, a phase difference occurs between the fundamental wave of the voltage signal and the measured current signal.

[0066] The above experimental results show that a fault signal due to a mechanical vibration component or an electrical fault signal can be distinguished from a signal due to a leakage component.

[0067] Fig. 4 shows the results of continuous monitoring of the deterioration state of the motor bearings from the initial state in the electric device 1 of this embodiment. In Fig. 4, the horizontal axis of the graph indicates the number of measurements at a certain unit time interval, which corresponds to the elapsed time. In Fig. 4, the vertical axis of the graph corresponds to THD (total harmonic distortion) and Ratio. For example, the THD value and Ratio value are expressed as a percentage (%).

[0068] THD is a value that evaluates the motor current spectrum according to the degree of harmonic distortion. Ratio indicates the ratio of the sum of the amplitudes of the outflow components to the RMS value (sum of the spectrum amplitudes) (i.e., sum of outflow components / RMS value). The ratio for the amplitude of the outflow components is calculated using the RMS value as the denominator. This allows the magnitude of the outflow components to be normalized with respect to amplitude fluctuations.

[0069] It is generally understood that as harmonic distortion increases, the motor is in a more severe state of failure. However, not all cases in which high harmonic distortion is detected are indicative of a motor failure.

[0070] THD does not show much change with bearing deterioration, and THD alone is not suitable for monitoring fault conditions.

[0071] In contrast, as shown in Figure 4, the ratio of outflow components to the RMS value tends to increase as the bearing deteriorates.

[0072] As shown in FIG. 4, in the analysis of the outflow component in this embodiment, it is found that the deterioration state of the motor bearing is well reflected in the ratio of the outflow component.

[0073] (c) Example of operation An example of the operation of the electric device 1 of this embodiment will be described with reference to Fig. 5. The operation of the electric device 1 of this embodiment relates to a method for controlling the electric device 1.

[0074] FIG. 5 is a flowchart showing an example of the operation of the electrical device 1 of this embodiment.

[0075] As shown in FIG. 5, when the electric device 1 of this embodiment is operating, the control device 30 performs frequency analysis of the electric signals (voltage signal and current signal) that drive the motor 11 (S1).

[0076] The control device 30 receives signals from the voltage detection circuit 21 and the current detection circuit 23. The control device 30 converts the signals from the voltage detection circuit 21 and the current detection circuit 23 into digital signals using the ADC 310. The ADC 310 sends the converted digital signals to the LPF 321. The LPF 321 performs LPF processing on the digital signals. The FFT calculator 322 performs FFT calculations on the LPF-processed digital signals.

[0077] The control device 30 calculates the phase angle and amplitude of the electrical signal that has been subjected to various processes through frequency analysis (S2).

[0078] The control device 30 compares the phase angle of the fundamental wave of the power supply frequency of the electrical signal (for example, a voltage signal) with the calculated phase angle of the electrical signal (for example, a current signal) (S3).

[0079] The control device 30 extracts and analyzes (S4) an outflow signal (anti-phase signal) indicating an outflow component from the motor 11. The outflow signal is a signal in which the phase angle of the current signal has a phase difference of ±90 degrees or more and 180 degrees or less with respect to the phase angle of the fundamental wave of the voltage signal.

[0080] The control device 30 extracts and analyzes (S5) an inflow signal (in-phase signal) indicating an inflow component to the motor 11. The inflow signal is a signal in which the phase angle of the current signal has a phase difference of less than ±90 degrees with respect to the phase angle of the fundamental wave of the voltage signal.

[0081] The control device 30 monitors the state inside the electric device 1 based on the analysis results of the outgoing signal and the incoming signal (S6). The control device 30 detects a failure of the motor 11 based on the outgoing signal. The control device 30 detects a failure on the AC power supply 10 side based on the incoming signal.

[0082] For example, the control device 30 calculates and analyzes the ratio of the sum of the inflow components to the RMS value (S60). For example, the control device 30 analyzes the sidebands of the fundamental wave of the voltage signal. For example, the control device 30 analyzes the harmonics of the fundamental wave (e.g., the third harmonic component). Based on the results of these analyses, the control device 30 detects a fault in the motor 11 and a malfunction in the AC power supply 10.

[0083] Through the above processing, the electric appliance 1 of this embodiment ends the operation for monitoring the inside of the electric appliance 1 by the control device 30. The control device 30 controls the operation of the electric appliance 1 based on the result of monitoring the electric appliance 1.

[0084] (d) Summary As described above, the electric device 1 of this embodiment acquires a signal indicating the outflow component that serves as a guide for detecting a failure of the motor 11 in the electric device 1 and a signal indicating the inflow component that grasps the state of the power source 10.

[0085] As a result, the electric device 1 of this embodiment can obtain feature quantities that enable accurate understanding of the fault conditions of the motor body, the motor load device, and the drive device. Furthermore, the electric device 1 of this embodiment can distinguish the effects of a fault on the power supply side from the effects of a fault occurring on the motor side.

[0086] As a result, the electric device 1 of this embodiment can achieve stable operation of the electric device.

[0087] (2) Second embodiment A control device and an electric device according to a second embodiment will be described with reference to FIGS.

[0088] In the above embodiment, an example was shown in which the outflow component of the electrical signal changes due to mechanical vibration in the induction motor. In this embodiment, an example in which the outflow component changes due to failure and deterioration on the stator side will be described.

[0089] As described above, in the electric device 1 of this embodiment, the failure detection unit 320 of the control device 30 monitors the ratio of the outflow component to the RMS value. In this way, in the electric device 1 of this embodiment, the control device 30 detects a failure of the motor 11.

[0090] FIG. 6 is a circuit diagram showing a circuit model of one phase of an induction motor (motor).

[0091] The motor 11 includes a stator 50 , an excitation circuit 51 , and a rotor 52 .

[0092] The stator 50 includes a resistance component 501 and an inductive reactance component 502 of the winding. The resistance component 501 and the inductive reactance component 502 are connected in series between the input node NDa and the node ND1. The resistance component 501 has a resistance value of "r1". The inductive reactance component 502 has a reactance value of "jx1".

[0093] The excitation circuit 51 includes an inductive reactance component 511 and a resistance component 512. The inductive reactance component 511 and the resistance component 512 are connected in parallel between a node ND1 and a node ND2. The node ND2 is connected to the input node NDb.

[0094] The rotor 52 is connected to the nodes ND1 and ND2 and includes an inductive reactance component 521, an inductive reactance component 522, an inductive reactance component 523, and a resistance component 524 of the winding.

[0095] The inductive reactance component 521 exists between the node ND1 and the node ND2. The inductive reactance component 522 is electromagnetically coupled to the inductive reactance component 521. The inductive reactance components 522 and 523 and the resistance component 524 are connected in series.

[0096] Inductive reactance components 521 and 522 have mutual inductance occurring between inductive reactance component 521 and inductive reactance component 522. Inductive reactance component 521 generates an excitation voltage of "E1". Inductive reactance component 522 generates an induced voltage of "E2". Inductive reactance component 523 has a reactance value of "jx2". Resistance component 524 has a resistance value of "r2 / s", where "s" is the slip.

[0097] The stator 50, the excitation circuit 51, and the rotor 52 are driven by the drive voltage Vin applied between the nodes NDa and NDb.

[0098] In the circuit model of FIG. 6, the inductive load changes due to the occurrence of a fault in the induction motor.

[0099] 6, the state of rotor 52 changes in accordance with the change in mutual inductance caused by mechanical vibration between inductive reactance components 521 and 522. This causes inductive fluctuations to appear in the current signal.

[0100] When a short circuit or partial discharge occurs on the stator 50 side, the magnitude of the resistance component or the magnitude of the inductive reactance component of the winding changes, which causes a change in current due to the inductive fluctuation.

[0101] These changes in current result in changes in the outflow component of the electrical signal, which can be detected.

[0102] Fig. 7 shows the change in motor current when a short circuit occurs in the winding of stator 50. In Fig. 7, the horizontal axis of the graph corresponds to the time (seconds) from the start of measurement, and the vertical axis of the graph corresponds to the amplitude value of the motor current.

[0103] In Fig. 7, the windings are forcibly (intentionally) short-circuited at time tx. As shown in Fig. 7, when a short circuit occurs in the windings, the value of the motor current increases after time tx.

[0104] At time tz, the short circuit in the winding is removed, causing the motor current to decrease from time tz onwards.

[0105] In this way, the amplitude of the motor current varies depending on whether or not the winding is short-circuited.

[0106] Fig. 8 shows the results of frequency analysis of motor current data for each unit time under the conditions of Fig. 7. Fig. 8 shows the results of comparing the ratio of the outflow component to the RMS value (RMS value / outflow component).

[0107] In Fig. 8, the horizontal axis of the graph corresponds to time (seconds), and the vertical axis of the graph corresponds to the ratio of the outflow component to the RMS value. In Fig. 8, the ratio of the outflow component to the RMS value for each of the U phase, V phase, and W phase is shown.

[0108] In this embodiment, the fault detection unit 320 continuously monitors the inflow signal, the outflow signal, and the ratio of the outflow component to the RMS value. The fault detection unit 320 monitors various values ​​in chronological order for each unit time, and determines the status of the power supply 10 and the motor 11 based on the frequency of changes in the various values.

[0109] 8, the induction motor maintains a normal state during a period T1 from the start of measurement to approximately time tx. During this period T1, the ratio of the loss component to the RMS value is small.

[0110] As shown in FIG. 7 above, immediately after a short circuit occurs in the induction motor at a certain time tx, a large change appears in the waveform of the motor current.

[0111] Therefore, as shown in Figure 8, the ratio of the outflow component to the RMS value also changes significantly.

[0112] During the period from time tx to time tz, a current imbalance occurs in the induction motor when a steady short circuit occurs. The ratio of the outflow component to the RMS value during this short circuit condition is greater than the ratio of the outflow component to the RMS value during normal current conditions.

[0113] At time tz, when the short circuit in the induction motor is cleared and the induction motor returns to normal, the change in the current waveform becomes significant. As a result, the ratio of the outflow component to the RMS value increases immediately after time tz.

[0114] As a result of the above changes, if a partial discharge occurs due to a partial short circuit in the wiring caused by poor insulation in the windings of the motor's stator 50, a change in inductance will occur, resulting in a large change in the outflow component of current.

[0115] Therefore, by observing the ratio of the outflow component to the RMS value, the fault detection unit 320 can sensitively detect the occurrence of partial discharge in the stator 50.

[0116] Furthermore, if a short circuit in a winding occurs continuously, the current waveform changes due to the occurrence of a current imbalance, and the ratio of the outflow component to the RMS value becomes larger than the ratio under normal conditions.

[0117] As described above, the electric device 1 of this embodiment can detect the presence or absence of a short circuit in the induction motor by constantly monitoring the ratio of the outflow component to the RMS value. As a result, the electric device 1 of this embodiment can accurately grasp the deterioration state caused by partial discharges and shocks that occur intermittently in the electric device 1.

[0118] Therefore, the electric device 1 of this embodiment can realize stable operation of the electric device.

[0119] (3) Third embodiment A control device and an electric device according to the third embodiment will be described with reference to FIG.

[0120] FIG. 9 is a circuit diagram showing an example of the configuration of the electric device 1 of this embodiment.

[0121] 9, the electric device 1 of this embodiment includes a power conversion device 40. The electric device 1 of this embodiment recognizes the fault state of the electric motor by the configuration of FIG.

[0122] The power conversion device 40 drives the motor 11 by converting power from the AC power supply 11. The power conversion device 40 includes a rectifier circuit 410, a switching circuit 420, and a smoothing capacitor 430.

[0123] The rectifier circuit 410 rectifies the supplied AC voltage. The rectifier circuit 410 outputs the rectified voltage (DC voltage). The rectifier circuit 410 includes a plurality of diodes 411. Two diodes 411 are connected in series between a high-potential node and a low-potential node of the power conversion device 40. The two diodes 411 connected in series form a leg. The multiple legs are connected in parallel with each other. The rectifier circuit 410 includes three legs corresponding to the U-phase, V-phase, and W-phase of the AC power supply 10.

[0124] The smoothing capacitor 430 smoothes the voltage (DC voltage) output from the rectifier circuit 410. The smoothing capacitor 430 is connected in parallel to the rectifier circuit 410 and the switching circuit 420 between the high-potential side node and the low-potential side node of the power conversion device 40.

[0125] The switching circuit 420 converts the supplied DC voltage into an AC voltage. The switching circuit 420 includes a plurality of switching elements 421. The switching elements 421 include an IGBT (Insulated Gate Bipolar Transistor) and a diode. Two switching elements 421 are connected in series between a high-potential node and a low-potential node of the power conversion device 40. The two switching elements 421 connected in series form a leg. The multiple legs are connected in parallel with each other. The switching circuit 420 includes three legs corresponding to the U-phase, V-phase, and W-phase of the motor 11.

[0126] Power converter 40 may include other components such as a DC reactor (not shown).

[0127] The AC power supply 10 is connected to a rectifier circuit 410 of the power conversion device 40. Wiring for each phase of the AC power supply 10 is connected to a corresponding one of three legs of the rectifier circuit 410.

[0128] The motor 11 is connected to a switching circuit 420 of the power conversion device 40. Wiring for each phase of the motor 11 is connected to a corresponding one of three legs of the switching circuit 420.

[0129] The voltage sensor circuit 20A senses the state of the voltage signal of each phase of the AC power supply 10. The voltage sensor circuit 20A monitors the input power supply voltage.

[0130] The voltage sensor circuit 20B senses the state of the DC voltage output from the rectifier circuit 410. The voltage sensor circuit 20B monitors the DC voltage after rectification.

[0131] The voltage detection circuit 21 transmits a voltage signal indicating the sensed result of the voltage sensor circuits 20A and 20B to the control device 30. The voltage signal is an analog signal.

[0132] The current sensor circuit 22 senses the drive current output from the switching circuit 420. The current sensor circuit 22 monitors the value of the drive current supplied to the motor 11.

[0133] The current detection circuit 23 transmits a current signal indicating the sensed result of the current sensor circuit 22 to the control device 30. The current signal is an analog signal.

[0134] The driver control circuit 25 generates a PWM (pulse width modulation) signal or a PAM (pulse amplitude modulation) signal in accordance with instructions from the control device 30. The driver control circuit 25 sends the PWM signal or the PAM signal to each switching element 421 of the switching circuit 420. In this way, the driver control circuit 25 drives the switching elements 421 of the switching circuit 420. The driver control circuit 25 is connected to the gate (control terminal) of each switching element 421.

[0135] The control device 30 converts the analog signals transmitted from the voltage detection circuit 21 and the current detection circuit 23 into digital signals using the ADC 310. The obtained digital signals are used to control the power conversion device 40.

[0136] The control device 30 generates a command signal for controlling the rotation state of the motor 11 in accordance with a command from the higher-level device 9. The control device 30 transmits the generated command signal to the driver control circuit 25. In this way, the control device 30 controls the operation of the motor 11 via the driver control circuit 25.

[0137] In this embodiment, the fault detection unit 320 of the control device 30 acquires a digital signal corresponding to the sensed result of the voltage sensor circuits 20A and 20B, and a digital signal corresponding to the sensed result of the current sensor circuit 22. In this way, the fault detection unit 320 constantly monitors the state of the power conversion device 40 and the state of the motor 11.

[0138] For example, the signal obtained from the voltage sensor circuit 20B includes a ripple voltage generated by the rectifier circuit 410. The ripple voltage appears as a second, fourth, or sixth harmonic of the power supply frequency.

[0139] In this embodiment, a signal (ripple signal) related to a ripple voltage included in a DC voltage is used as a fundamental frequency (fundamental wave), and the phase difference between the phase of the fundamental wave of the voltage signal and the phase of the current signal is compared. This allows the fault detection unit 320 of the control device 30 in the electrical device 1 of this embodiment to distinguish between an outflow signal and an inflow signal.

[0140] Generally, if the switching circuit 420, the smoothing capacitor 430, or the DC reactor (not shown) is operating normally, the outflow component of the electrical signal will not become large in the frequency analysis of the voltage signal.

[0141] However, when a failure occurs in a circuit component, a change in the outflow component of the electrical signal is observed as an inductive load fluctuation, and therefore the failure detection unit 320 can detect the occurrence of a failure in a circuit component by analyzing the outflow component of the electrical signal.

[0142] In the signal obtained from the current sensor circuit 22, the signal component of the drive frequency is the main component of the signal related to the current when driving the motor 11. However, the signal related to the current also contains harmonics or switching noise from the switching circuit 420 as signal components.

[0143] When detecting a bearing failure by analyzing the motor current, sidebands shifted by the rotation frequency with the drive frequency as the center are observed.

[0144] Because the observed switching noise occurs in synchronization with the drive frequency, the switching noise can be detected as an inflow component that is approximately in phase with the drive frequency. Because the phase of the sideband wave signal generated by the mechanical vibration of the motor 11 differs from the phase of the drive frequency, the signal caused by the sideband wave can be detected as an outflow component.

[0145] As a result, in this embodiment, the control device 30 can separate noise caused by the power conversion device 40 using the failure detection unit 320, and can clearly detect the failure state of the motor 11.

[0146] When the signal obtained from voltage sensor circuit 20A or voltage sensor circuit 20B is considered as an inflow component in phase with the power supply frequency, it is possible to monitor the state of defects and failures on the AC power supply 10 side. In other words, the inflow component separated by frequency analysis of the voltage signal represents the signal state on the AC power supply 10 side.

[0147] This allows the control device 30 to detect external noise, harmonics, and the occurrence of faults such as partial discharge or short circuit in the electrical wiring.

[0148] Therefore, in the electric device 1 of this embodiment, the control device 30 including the failure detection unit 320 can distinguish between failures on the motor 11 and power conversion device 40 side and defects due to failures on the power supply 10 side, i.e., the system and power transmission side.

[0149] As described above, the electric device 1 of this embodiment can realize stable operation of the electric device.

[0150] In the control device 30 of the electric device 1 of this embodiment, the fault detection unit 320 calculates and analyzes the inflow component signal and the outflow component signal. In this way, the fault detection unit 320 detects a fault state that has occurred in the electric device 1.

[0151] (4) Variations A modified example of the electric device of the embodiment will be described with reference to FIG.

[0152] FIG. 10 is a circuit diagram showing a modified example of the electric device 1 of the embodiment.

[0153] In the above-described embodiment, the higher-level device 9 may perform the calculation and analysis of the inflow component signal and the outflow component signal to grasp the fault state, instead of the fault detection unit 320 (and the control device 30).

[0154] That is, the failure detection unit 320 in the electric device 1 only has the function of communicating various electric signals to the higher-level device 9 in the electric device 1 .

[0155] 10 , the higher-level device 9 includes a fault detection unit 320X. The higher-level device 9 uses the fault detection unit 320X to perform frequency analysis, calculate the phase angle and amplitude, compare the fundamental wave with the electrical signal and the phase difference, extract the inflow component, and extract the outflow component based on the signal from the fault detection unit 320 of the electrical device 1.

[0156] In this way, the host device 9 can grasp the fault state in the electric device 1 from outside the electric device 1. Therefore, the host device 9 functions as a control device for the motor 11 and the electric device 1.

[0157] In the higher-level device 9, the various functions implemented as the failure detection unit 320 as shown in FIG. 2 are implemented and operated by software as algorithms and analysis methods.

[0158] This reduces the computational load of the edge device (electrical device 1) in a system (network) including the electric device 1 and the higher-level device 9.

[0159] When the detection of electrical equipment failures based on the above-mentioned outflow and inflow components is applied to an existing system, as in this modified example, the upper level device 9 capable of detecting failures in the embodiment can operate the entire system in a highly scalable state without adding a failure detection unit 320 to the existing electrical equipment.

[0160] As described above, this modification allows the system including the electric device 1 to operate stably.

[0161] (5) Other The electric device 1 and the control device 30 of the above-described embodiment can be applied to railway vehicles, industrial plants, transport systems, or the like.

[0162] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0163] 1: Electrical equipment, 10: AC power supply, 11: Motor, 20: Voltage sensor circuit, 21: Voltage detection circuit, 22: Current sensor circuit, 23: Current detection circuit, 25: Driver control circuit, 30: Control device, 310: ADC, 320: Fault detection unit, 330: Control unit, 40: Power conversion device, 410: Rectifier circuit, 411: Diode, 420: Switching circuit, 421: Switching element, 430: Smoothing capacitor

Claims

1. a control unit that controls the electric motor; a failure detection unit that detects a failure of the electric motor; Equipped with The failure detection unit performing a frequency analysis on an electrical signal that drives the electric motor; calculating the phase of the electrical signal; calculating a phase difference between the phase of a fundamental wave of a power supply frequency of the electrical signal and the calculated phase of the electrical signal; extracting a first signal indicating an outflow component from the electric motor based on a calculation result of the phase difference; extracting a second signal indicating an inflow component to the electric motor based on the calculation result of the phase difference; detecting the fault based on the first signal; Control device.

2. the outflow component is a component in which a phase difference between a phase of a fundamental wave of a voltage signal included in the electrical signal and a phase of the calculated current signal included in the electrical signal has a value within a range from 0 degrees to +90 degrees and a range from 0 degrees to −90 degrees; The inflow component is a component in which the phase difference between the phase of the fundamental wave of the voltage signal and the phase of the current signal has a value within a range from +90 degrees to +180 degrees and from −90 degrees to −180 degrees. The control device according to claim 1 .

3. The failure detection unit comparing the first signal with a third signal indicative of a normal condition of the motor; monitoring a state of the electric motor based on a result of comparing the first signal with the third signal; The control device according to claim 1 .

4. The failure detection unit comparing the second signal with a third signal indicative of a normal condition of the motor; monitoring a state of a power supply based on a result of a comparison between the second signal and the third signal; The control device according to claim 1 .

5. The failure detection unit calculating the amplitude of the electrical signal; monitoring a state of the electric motor based on a first ratio between a first value indicating a spectrum sum obtained by the frequency analysis and a second value indicating a sum of amplitudes of the first signals; The control device according to claim 1 .

6. The failure detection unit monitoring the first ratio; monitoring a state of the electric motor based on a frequency of changes in the first ratio within a certain period of time; The control device according to claim 5 .

7. The failure detection unit monitoring a DC voltage in a power converter that drives the electric motor; Using a ripple signal included in the DC voltage as the fundamental wave, calculate the phase difference between the phase of the fundamental wave of the electrical signal and the calculated phase of the electrical signal; extracting the first signal and the second signal based on the calculation result of the phase difference; The control device according to claim 1 .

8. the failure detection unit monitors a state of the power conversion device based on a change in the first signal obtained from a monitoring result of the DC voltage. The control device according to claim 7.

9. the failure detection unit monitors the state of the power supply based on a change in the second signal obtained from a monitoring result of the DC voltage. The control device according to claim 7.

10. an electric motor connected to a power source; a control device according to claim 1 that controls the electric motor and detects a failure of the electric motor; Electrical equipment equipped with:

11. performing a frequency analysis on an electrical signal that drives an electric motor; calculating the phase of the electrical signal; calculating a phase difference between a phase of a fundamental wave of a power supply frequency of the electrical signal and the calculated phase of the electrical signal; extracting a first signal indicating an outflow component from the electric motor based on a calculation result of the phase difference; detecting a fault based on the first signal; A method for controlling an electrical device comprising:

Images