JP5622670B2 - Insulation deterioration diagnosis device - Google Patents

Description

  The present invention relates to an insulation deterioration diagnosis apparatus.

  In general, as a technique for diagnosing insulation deterioration of motor circuits such as motors, inverters, and electric wires that connect the two, a method of diagnosing insulation deterioration using a current flowing by applying a voltage from the outside, or a zero detected by a current transformer A method for diagnosing insulation deterioration by phase current is known. When these methods are applied to a motor system in which a plurality of inverters and motors are connected to a direct current power supply (or one converter) to diagnose insulation deterioration, a diagnosis circuit and a diagnosis device corresponding to the number of motors to be diagnosed. Therefore, the apparatus tends to be enlarged.

  On the other hand, in Patent Document 1, in a motor drive device in which a plurality of inverter units are connected to one converter unit, an electromagnetic wave between a three-phase AC power source and the converter unit is detected when insulation deterioration is detected. It is described that the contactor is turned off, one end of the smoothing capacitor in each inverter unit is grounded by a first switch, and the other end of the smoothing capacitor is connected to the winding of the motor by a second switch. Thus, according to Patent Document 1, since the motor insulation resistance is calculated from the current value measured by the current measurement circuit attached to each motor and the voltage value measured by the voltage measurement circuit in the converter, the minimum circuit configuration In addition, it is supposed that the insulation resistance deterioration can be detected by the component parts.

  In Patent Document 2, a detection resistance element is connected to a circuit between a plurality of inverters driven at mutually different PWM carrier frequencies and a high-voltage battery via a coupling capacitor. It is described that a ground insulation failure of a motor circuit system is detected based on a drop. Specifically, only the AC voltage component corresponding to the PWM carrier frequency of each inverter in the voltage drop of the detection resistor element is individually extracted by each tuning filter, and the magnitude of the output voltage of each tuning filter is set to a predetermined value. The presence or absence of ground insulation failure of a plurality of inverter control motors is determined by comparison with a threshold value. Thereby, according to patent document 2, it is supposed that the inverter control motor in which the ground insulation failure has occurred can be specified while suppressing an increase in cost and space.

Japanese Patent No. 4565036 Japanese Patent No. 4098069

  In the motor driving device described in Patent Document 1, since it is necessary to switch the electric circuit in order to detect insulation deterioration, it is necessary to completely stop a load device such as a motor when switching the electric circuit. It is difficult to detect insulation deterioration. For this reason, it is difficult to prevent deterioration of insulation particularly in devices that require continuous operation for a long time.

  Moreover, in the motor drive device described in Patent Document 1, it is necessary to provide a current measurement circuit for measuring the current flowing through the motor by the number corresponding to the number of motors, so that the number of motors to be connected increases. Cost tends to increase.

  On the other hand, the insulation failure detection circuit described in Patent Document 2 is applied to a configuration in which a plurality of inverters having the same PWM carrier frequency are connected to separate AC voltage components corresponding to the PWM carrier frequency. In addition, it is not possible to specify a motor that is in an insulating deterioration state.

  In addition, since the insulation failure detection circuit described in Patent Document 2 needs to design a tuning filter having a frequency corresponding to the PWM carrier frequency in advance, when newly installing an inverter having a different PWM carrier frequency, the tuning filter must be re-installed. It is necessary to design and it is difficult to flexibly change the operating frequency of the motor. It is also difficult to change the system configuration flexibly.

  Assuming a configuration in which tuning filter processing is performed by digital signal processing so that the motor operating frequency can be flexibly changed, frequency components with a high band such as PWM carrier frequency are sampled and frequency separation is performed. For this purpose, a fine sampling period is required. For example, in order to separate an AC voltage component having a PWM frequency of 10 kHz, a sampling frequency of at least 20 kHz or more (sampling period is 50 μs) or more is required, and the sampling period is fine and a filter such as a bandpass filter (bandpass filter) is used. If processing is to be performed, the processing load increases, which is not suitable for real-time detection.

  The present invention has been made in view of the above, and an object of the present invention is to obtain an insulation deterioration diagnosis apparatus that can specify an insulation deterioration axis without switching an electric circuit and can flexibly change an operating frequency of a motor.

  In order to solve the above-described problems and achieve the object, an insulation deterioration diagnosis device according to one aspect of the present invention includes a leakage current detection unit that detects a leakage current flowing in an electric circuit between a plurality of motors and a power supply. A frequency component classification unit that classifies a plurality of frequency components corresponding to a plurality of angular frequencies calculated by an angular frequency calculation unit that calculates an angular frequency of an electrical angle of the plurality of motors from the detected leakage current; and the classification And an insulation deterioration axis specifying unit that specifies an insulation deterioration axis among a plurality of axes corresponding to the plurality of motors based on the current amplitudes of the plurality of frequency components.

  According to the present invention, since the insulation deterioration axis is specified using the detection result of the leakage current flowing in the electric circuit between the plurality of motors and the AC power supply, the insulation deterioration axis can be specified without switching the electric circuit. In addition, since the insulation deterioration axis is specified by using the result of separating the plurality of frequency components corresponding to the plurality of angular frequencies calculated by the angular frequency calculation unit from the leakage current, instead of the predetermined frequency, the insulation deterioration axis It is easy to flexibly change the operating frequency of the motor when specifying the motor. That is, it is possible to specify the insulation deterioration axis without switching the electric circuit and to flexibly change the operating frequency of the motor.

FIG. 1 is a diagram illustrating a configuration of the insulation deterioration diagnosis apparatus according to the first embodiment. FIG. 2 is a flowchart showing the operation of the insulation deterioration diagnosis apparatus in the first embodiment. FIG. 3 is a diagram illustrating a configuration of the insulation deterioration diagnosis apparatus according to the second embodiment. FIG. 4 is a flowchart illustrating the operation of the insulation deterioration diagnosis apparatus according to the second embodiment.

  Embodiments of an insulation deterioration diagnosis apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
An insulation deterioration diagnosis apparatus 10 according to the first embodiment will be described.

  The insulation deterioration diagnosis device 10 is a device for diagnosing an insulation deterioration state in an inverter-driven device, and can be used particularly for diagnosing insulation deterioration in a shaft corresponding to a motor.

  FIG. 1 is a diagram showing an example when the insulation deterioration diagnosis device 10 is attached to the motor system MS. The motor system MS has an AC power supply AC and a converter CV, and includes n inverters INV-1 to INV-n, motors M-1 to Mn, and position detectors ENC-1 to ENC as the n shafts connected thereto. -N for each axis. Each motor M-1 to M-n is, for example, an AC motor. In the motor system MS, an AC power source AC is connected to one converter CV on one end side, and a plurality of motors M-1 to M- are connected to the other end side via a plurality of inverters INV-1 to INV-n. n is connected. Each position detector ENC-1 to ENC-n detects the position of the rotor (or mover) in the corresponding motor M-1 to Mn, and outputs position information P1 to Pn indicating the detected position. To do. Each position detector ENC-1 to ENC-n is, for example, an encoder or a resolver. Note that the number after the hyphen “-” in the member number corresponds to the axis number.

  As shown in FIG. 1, the motor system MS further includes a leakage current detection unit 20 and an angular frequency calculation unit 30.

  Leakage current detection unit 20 detects a leakage current IL flowing in the electric path between AC power supply AC and a plurality of motors M-1 to M-n. The leakage current detection unit 20 includes a current transformer 21. The current transformer 21 is, for example, disposed between the AC power supply AC and the converter CV, and detects a leakage current IL that flows in an electric path between the AC power supply AC and the converter CV. The leakage current detection unit 20 supplies the detected leakage current IL to the insulation deterioration diagnosis device 10.

  The leakage current detection unit 20 is not limited to the above path as long as the leakage current IL is generated when the shaft subjected to the insulation deterioration state diagnosis is in the insulation deterioration state. . For example, in the case where one converter CV is connected to the AC power supply AC shown in FIG. 1 and the converter CV and a plurality of inverters INV-1 to INV-n are connected, the AC power supply AC and the converter CV A zero-phase current transformer as a current transformer 21 may be attached to the electric circuit between them, and the zero-phase current measured from the zero-phase current transformer may be detected as the leakage current IL, or the converter CV and the inverters INV-1 to INV- You may detect the direct current which flows between the electric circuit between n, and the earth as leakage current IL.

  In addition, since a leakage breaker is usually attached to an electrical device, a signal from a current transformer built in the leakage breaker may be used as the leakage current IL.

  Furthermore, when the zero-phase current obtained by the zero-phase current transformer as the current transformer 21 is a minute current, the leakage current detection unit 20 may further include an amplifier circuit 22. That is, the leakage current IL detected by the current transformer 21 and amplified through the amplifier circuit 22 may be supplied to the insulation deterioration diagnosis device 10. On the other hand, if the zero-phase current obtained by the zero-phase current transformer is not very small, it is not necessary to provide an amplifier circuit.

  The angular frequency calculator 30 calculates the angular frequencies F1 to Fn of the electrical angles of the plurality of motors from the position information P1 to Pn output from the position detectors ENC-1 to ENC-n. Specifically, the angular frequency calculation unit 30 includes n angular frequency calculation units 31-1 to 31-n corresponding to n axes. Each angular frequency calculation unit 31-1 to 31-n receives position information P1 to Pn output from the corresponding position detectors ENC-1 to ENC-n, and corresponds from the received position information P1 to Pn. The angular frequency of the electrical angle of the motors M-1 to M-n is calculated. Each angular frequency calculation unit 31-1 to 31-n supplies the calculated angular frequency to the insulation deterioration diagnosis device 10. That is, the angular frequency calculation unit 30 supplies the calculated plurality (n) of angular frequencies to the insulation deterioration diagnosis device 10.

  In addition, each angular frequency calculation part 31-1 to 31-n outputs the output signals (position feedback value and speed feedback value) of the position detectors ENC-1 to ENC-n attached to the motors M-1 to M-n. The actual motor angular velocity (the angular frequency of the mechanical angle) is calculated from the motor, and the frequency obtained by multiplying the motor angular velocity by the number of pole pairs (or 1/2 of the number of poles) that is unique to the motors M-1 to M-n is used as the motor. You may output as angular frequency F1-Fn of the electrical angle of M-1 to M-n.

  Further, each of the angular frequency calculation units 31-1 to 31-n does not use the output signals of the position detectors ENC-1 to ENC-n, and sets the motor M- to the command angular velocity to the motors M-1 to M-n. A frequency obtained by multiplying the number of pole pairs (or ½ of the number of poles), which is a value unique to 1 to M−n, may be used as the angular frequency of the electrical angle of the motor M−1 to M−n.

  However, when using the motor angular velocity or the value calculated from the commanded angular velocity for the motor as the angular frequencies F1 to Fn of the electrical angles of the motors M-1 to M-n, and the motors M-1 to M- In the case of a motor in which n has slip (such as an induction motor), the angular frequency of the electrical angle of the motors M-1 to M-n considering slip is used.

  Further, the angular frequencies F1 to Fn of the electrical angles of the motors M-1 to Mn change the alternating currents flowing through the motors M-1 to Mn connected to the inverters INV-1 to INV-n, respectively. The angular frequency of the electrical angle of the motor obtained from a signal measured by a measuring means such as the fluency device 21 using a known frequency separation technique (bandpass filter, tuning filter, resonance filter, frequency analysis (FFT analysis), etc.) It may be used.

  Next, the configuration of the insulation deterioration diagnosis device 10 will be described.

  The insulation deterioration diagnosis device 10 includes a frequency component sorting unit 11 and an insulation deterioration axis specifying unit 12.

  The frequency component classification unit 11 receives the detected leakage current IL from the leakage current detection unit 20 and receives the calculated angular frequencies F1 to Fn from the angular frequency calculation unit 30. The frequency component classification unit 11 classifies a plurality of frequency component signals FL1 to FLn corresponding to the plurality of angular frequencies F1 to Fn calculated by the angular frequency calculation unit 30 from the leakage current IL detected by the leakage current detection unit 20. To do. Then, the frequency component sorting unit 11 outputs the frequency component signals FL1 to FLn and current amplitudes AL1 to ALn that are the amplitudes of FL1 to FLn to the insulation degradation axis specifying unit 12. Here, the frequency component corresponding to the angular frequency may be separated by a configuration obtained by improving a known frequency separation technique (bandpass filter, tuning filter, resonance filter, frequency analysis (FFT analysis), etc.).

  For example, the frequency component classification unit 11 may include a control signal generation unit 11a, n band pass filters 11b-1 to 11b-n each having a variable pass band, and an arithmetic circuit 11c. For example, when the frequency component corresponding to the angular frequency F1 is separated using a bandpass filter, the control signal generation unit 11a performs a predetermined calculation (for example, a predetermined coefficient) on the angular frequency F1, A control signal for adjusting the passband to one corresponding to the angular frequency F1 is generated and supplied to the control terminal of the bandpass filter 11b-1. Accordingly, the leakage current IL is passed through the band-pass filter 11b-1 whose pass band is adjusted to correspond to the angular frequency F1. Thereby, the frequency component signal FL1 is obtained. At this time, since the frequency component signal FL1 is an AC signal, the arithmetic circuit 11c calculates the maximum value or the minimum value of the frequency component signal FL1 and outputs it as the current amplitude AL1. The same applies to the separation of the frequency components corresponding to the other angular frequencies F2 to Fn, and the arithmetic circuit 11c calculates the maximum value or the minimum value of the frequency component signals FL2 to FLn and outputs them as current amplitudes AL2 to ALn.

  The insulation deterioration axis specifying unit 12 receives the calculated angular frequencies F <b> 1 to Fn from the angular frequency calculating unit 30. Further, the insulation degradation axis specifying unit 12 receives the frequency component signals FL1 to FLn of the separated leakage current IL and the current amplitudes AL1 to ALn from the frequency component sorting unit 11. The insulation deterioration axis specifying unit 12 divides the calculated angular frequencies F1 to Fn, the frequency component signals FL1 to FLn of the separated leakage current IL, and the current amplitudes AL1 to ALn of the divided frequency components. Based on the plurality of shafts corresponding to the plurality of motors M-1 to Mn, the insulation deterioration axis is specified. For example, the insulation deterioration axis specifying unit 12 compares each absolute value of the current amplitudes AL1 to ALn of a plurality of frequency components with a predetermined threshold value, and extracts a frequency component having an absolute value of a current amplitude larger than the predetermined threshold value. Then, the axis corresponding to the frequency component is specified as the insulation deterioration axis. The insulation deterioration axis specifying unit 12 outputs an insulation deterioration axis specification result, that is, an insulation deterioration diagnosis result to the display device 40. Thereby, the insulation deterioration diagnosis result is displayed on the screen of the display device 40.

  Next, the operation of the insulation deterioration diagnosis apparatus 10 will be described with reference to FIG. FIG. 2 is a flowchart showing the operation of the insulation deterioration diagnosis apparatus 10.

  In step ST21, the insulation deterioration axis specifying unit 12 has a current amplitude greater than or equal to the threshold by comparing the current amplitudes AL1 to ALn of the frequency component signals FL1 to FLn sorted by the frequency component sorting unit 11 with a predetermined threshold. Extract all angular frequencies of electrical angle.

  Specifically, the insulation deterioration axis specifying unit 12 receives the calculated angular frequencies F <b> 1 to Fn from the angular frequency calculating unit 30. Further, the insulation degradation axis specifying unit 12 receives the frequency component signals FL1 to FLn of the separated leakage current IL and the current amplitudes AL1 to ALn from the frequency component sorting unit 11. The insulation deterioration axis specifying unit 12 compares each of the current amplitudes AL1 to ALn of the plurality of frequency components with a predetermined threshold value, and extracts a frequency component having a current amplitude larger than the predetermined threshold value.

  The magnitude of each frequency component AL1 to ALn of the leakage current IL depends on the voltage applied to the motors M-1 to Mn, and the voltage applied to the motors M-1 to Mn is the number of rotations of the motor. For example, it is desirable to change the threshold value for detecting the deterioration of insulation in accordance with the number of rotations of the motor. Specifically, the electrical angles of the motors M-1 to M-n are desirable. As the frequency increases, the threshold for detecting insulation deterioration is increased.

  However, depending on the motor output characteristics, the voltage applied to the motor may not increase (saturate) even if the motor speed is increased. Therefore, the motor output characteristics should be taken into account and change depending on the motor speed. It is desirable to make it.

  Further, instead of extracting the angular frequency of the electrical angle by comparing the current amplitude and the threshold as described above, the voltage applied to the motors M-1 to Mn is divided by the angular frequency components AL1 to ALn. The insulation resistance values of the motors M-1 to Mn may be calculated, and determination may be made based on whether or not the insulation resistance values of the motors M-1 to Mn are equal to or greater than a threshold value.

  In step ST22, the insulation deterioration axis specifying unit 12 determines whether there is a frequency component having a current amplitude larger than a predetermined threshold. If there is a frequency component having a current amplitude larger than a predetermined threshold value, the insulation deterioration axis specifying unit 12 determines that there is an insulation deterioration state axis, and proceeds to step ST23. Further, the insulation deterioration axis specifying unit 12 does not have a frequency component having a current amplitude larger than a predetermined threshold, and all the axes corresponding to the rotating motors M-1 to M-n are not in the insulation deterioration state (a healthy state). ), The process proceeds to step ST24.

  Note that the shaft state determination (determination of whether the state is healthy or abnormal) corresponding to a motor that is not in a rotating state is not performed, and the determination is suspended until a rotating operation is performed.

  In step ST23, the insulation deterioration axis specifying unit 12 compares the angular frequencies FL1 to FLn extracted in step ST21 with the angular frequencies F1 to Fn of the electrical angles of the motors M-1 to Mn, and insulation deterioration occurs. The axis corresponding to the motor rotating at the same electrical angular frequency as the angular frequencies FL1 to FLn extracted as being specified is specified as the insulation deterioration axis.

  In step ST24, the insulation deterioration axis specifying unit 12 outputs the determination result in step ST22 or the insulation deterioration diagnosis result specified in step ST23 to the display device 40, for example. Thereby, the insulation deterioration diagnosis result is displayed on the screen of the display device 40, for example.

  Here, in order to detect insulation deterioration, the connection between the AC power source AC and the converter CV is turned off, and one end of the smoothing capacitor in each inverter unit is grounded by the first switch and the other end of the smoothing capacitor is connected to the other end. Consider a case in which the insulation resistance of a motor is calculated from a current value measured by a current measurement circuit attached to each motor and a voltage value measured by a voltage measurement circuit in a converter, connected to the motor winding by a second switch. In this case, it is necessary to completely stop the load device such as a motor at the time of switching the electric circuit, and it is difficult to detect insulation deterioration while the load device is being driven. For this reason, it is difficult to prevent deterioration of insulation particularly in devices that require continuous operation for a long time.

  On the other hand, in the first embodiment, the frequency component sorting unit 11 uses the leakage current detection unit 20 that detects the leakage current IL flowing in the electric path between the plurality of motors M-1 to Mn and the AC power supply AC. A plurality of frequency components (a plurality of frequency components corresponding to the plurality of angular frequencies calculated by the angular frequency calculating unit 30 that calculates the angular frequency of the electrical angle of the plurality of motors M-1 to M-n from the detected leakage current IL. The frequency component signals FL1 to FLn) are separated. And the insulation degradation axis | shaft specific | specification part 12 is insulation degradation among the some axes | shafts corresponding to several motors M-1 to Mn based on the current amplitude of the several frequency component sorted by the frequency component classification | category part 11. FIG. Identify the axis. As a result, even in an electric device that operates continuously for a long time, the insulation deterioration axis can be identified without switching the electric circuit, and it is easy to prevent the insulation deterioration. That is, it is possible to always detect the insulation deterioration axis.

  In addition, when switching the electric circuit and calculating the insulation resistance of the motor from the current value measured by the current measurement circuit attached to each motor and the voltage value measured by the voltage measurement circuit in the converter, the number of motors corresponding to the number of motors Since it is necessary to provide a current measurement circuit for measuring the current flowing in the circuit, the cost tends to increase as the number of connected motors increases.

  On the other hand, in the first embodiment, the leakage current detection unit 20 that detects the leakage current IL flowing in the electric path between the plurality of motors M-1 to Mn and the AC power supply AC is common to the plurality of axes. Therefore, even if the number of shafts corresponding to the motor to be connected increases, an increase in cost can be suppressed.

  In addition, when switching the electric circuit and calculating the insulation resistance of the motor from the current value measured by the current measurement circuit attached to each motor and the voltage value measured by the voltage measurement circuit in the converter, connections to multiple motors are made sequentially. Since it is necessary to detect insulation deterioration by switching, the processing time for detecting insulation deterioration tends to be longer.

  On the other hand, in Embodiment 1, the process for the insulation deterioration with respect to the some axis | shaft corresponding to a some motor is performed in parallel. That is, since a plurality of axes corresponding to a plurality of motors can be collectively checked, it is possible to shorten the processing time for detecting insulation deterioration.

  Alternatively, suppose that a detection resistance element is connected to a circuit between a plurality of inverters INV-1 to INV-n driven by a plurality of PWM carrier frequencies and an AC power supply AC via a coupling capacitor. Consider a case in which insulation deterioration of each axis is detected by separating an AC voltage component corresponding to each PWM carrier frequency from the voltage drop. In this case, if one of the plurality of inverters INV-1 to INV-n is driven at the same PWM carrier frequency, one of the two or more axes corresponding to the inverter driven at the same PWM carrier frequency When insulation deterioration has occurred on one shaft and insulation deterioration has not occurred on the remaining shafts, it cannot be specified which shaft has undergone insulation deterioration.

  On the other hand, in the first embodiment, the insulation deterioration axis specifying unit 12 performs insulation deterioration diagnosis using the angular frequency of the electrical angle of the motor. For this reason, even when a plurality of inverters having the same PWM carrier frequency are used, if the angular frequency of the electrical angle of the motor is different, it is possible to identify the shaft that has undergone insulation degradation.

  Further, the AC voltage component corresponding to each PWM carrier frequency is separated from the voltage drop of the detection resistance element connected via a coupling capacitor to the electric circuit between the plurality of inverters INV-1 to INV-n and the AC power supply AC. In order to perform the separation, it is necessary to design a tuning filter having a frequency corresponding to the PWM carrier frequency in advance. When newly installing an inverter having a different PWM carrier frequency, it is necessary to redesign the tuning filter, and it is difficult to flexibly change the operating frequency of the motor. It is also difficult to change the system configuration flexibly.

  On the other hand, in the first embodiment, the frequency component classification unit 11 is not a predetermined frequency, but a plurality of frequency components (a plurality of frequency components) corresponding to a plurality of angular frequencies calculated by the angular frequency calculation unit 30. The signals FL1 to FLn) are separated from the leakage current IL. Thereby, it is easy to flexibly change the operating frequency of the motor. It is also easy to change the system configuration flexibly.

  Further, the AC voltage component corresponding to each PWM carrier frequency is separated from the voltage drop of the detection resistance element connected via a coupling capacitor to the electric circuit between the plurality of inverters INV-1 to INV-n and the AC power supply AC. Consider that the tuning filter used for the separation is digital signal processing so that the operating frequency of the motor can be flexibly changed when performing the above. In this case, in order to sample a frequency component having a high band like the PWM carrier frequency and perform frequency separation, a fine sampling cycle is required. For example, in order to separate an AC voltage component having a PWM frequency of 10 kHz, a sampling frequency of at least 20 kHz or more (sampling period is 50 μs) or more is required, and the sampling period is fine and a filter such as a bandpass filter (bandpass filter) is used. If processing is to be performed, the processing load increases, which is not suitable for real-time detection.

  On the other hand, in the first embodiment, the frequency component classification unit 11 performs diagnosis using the angular frequency of the electrical angle of the motor, and thus performs frequency classification with a frequency signal lower than the PWM carrier frequency. As a result, the processing load can be reduced even when the frequency separation of the leakage current is performed by digital processing.

Embodiment 2. FIG.
An insulation deterioration diagnosis apparatus 10i according to the second embodiment will be described with reference to FIG. FIG. 3 is a diagram showing an example when the insulation deterioration diagnosis device 10i is attached to the motor system MS. Below, it demonstrates focusing on a different part from Embodiment 1. FIG.

  In the second embodiment, when there are a plurality of axes having the same angular frequency of the electrical angle among a plurality of axes corresponding to the plurality of motors M-1 to M-n, an axis specifying operation command is generated. Then, using the axis specifying operation command, the angular frequencies of the axes having the same angular frequency are changed to different ones, and the insulation deterioration axis is specified in this state.

  Specifically, the insulation deterioration diagnosis device 10i further includes an axis specifying operation command generation unit 13i. The axis specifying operation command generating unit 13i receives the identification results (insulation deterioration diagnosis result) of the plurality of angular frequencies F1 to Fn and the insulating deterioration axis from the insulating deterioration axis specifying unit 12. The axis specifying operation command generation unit 13i is insulated on two or more axes corresponding to two or more motors operating at the same angular frequency among the plurality of angular frequencies F1 to Fn according to the identification result of the insulation deterioration axis. When it is determined that there is deterioration, an axis specifying operation command is given to one or more motors out of two or more motors operating at the same angular frequency via the inverters INV-1 to INV-n. The axis specifying operation command is a command for operating two or more motors operating at an angular frequency of the same electrical angle at different angular frequencies.

  Further, as shown in FIG. 4, the operation of the insulation deterioration diagnosis device 10i is different from that of the first embodiment in the following points. FIG. 4 is a flowchart showing the operation of the insulation deterioration diagnosis device 10i.

  In the flowchart shown in FIG. 4, the processes of step ST33 and step ST35 are further performed.

  In step ST33, the insulation deterioration axis specifying unit 12 performs processing branching according to the number of motors rotating at the angular frequency extracted in step ST21. That is, when the number of motors rotating at the angular frequency extracted in step ST21 is 1, the insulation deterioration axis specifying unit 12 determines that the corresponding motor is in an insulation deterioration state, and the process is performed in step ST23. Proceed to Moreover, the insulation deterioration axis | shaft specific | specification part 12 advances a process to step ST35, when the number of the motors rotated with the angular frequency extracted by step ST21 is two or more.

  In step ST35, in order to instruct | indicate the operation | movement for specifying the axis | shaft in an insulation degradation state from two or more motors which the insulation degradation axis | shaft specific | specification part 12 rotates with the same angular frequency, several angular frequency F1- The result of specifying Fn and the insulation deterioration axis is output to the axis specifying operation command generator 13i. The axis specifying operation command generation unit 13i generates an axis specifying operation command for specifying an axis in an insulation deterioration state from two or more motors operating at an angular frequency of the same electrical angle. And the process similar to step ST23 is performed and an insulation degradation axis | shaft is specified.

  Here, the generation of the axis specifying operation command is performed by isolating the original operation command (positioning command, constant velocity command, etc.) from at least one of the axes operating at the same electrical angular frequency. The inverter INV-1 to INV-n is instructed to change to the operation command for specifying the deteriorated axis or to superimpose the operation command for specifying the insulation axis on the original operation command.

  For example, a command that includes a frequency component other than a frequency that is an integral multiple of the commercial power supply frequency or a frequency component other than a frequency that is an integer multiple of the electrical frequency (F1 to Fn) of the motors is superimposed on the original command. This command is given as an axis specifying operation command. As a result, the inverters INV-1 to INV-n of the motors M-1 to M-n instructed to perform the axis specifying operation perform inverter control based on the instructed commands and drive the motors M-1 to M-n. To do.

  The axis specifying operation command superimposed on the original operation command is, for example, any one of a D-axis current command, a Q-axis current command, a speed command, and a position command. When instructing the operation, the commands having different frequencies are issued.

  When superimposing a command on one of the axes corresponding to a motor rotating at the same frequency, a combination of a number of frequency signals such as a triangular wave, a sawtooth wave, a rectangular wave, and an M-sequence signal is combined. May be determined, and based on a change from the frequency characteristics of the original leakage current command, it may be determined that the insulation deterioration state.

  Also, the axis specifying operation command for changing the original operation command is such that when it is determined that there are a plurality of shafts having the same electric angular frequency of the motor, the speed command to the motor is moved with different frequencies. By changing, the angular frequency of the current angle of the motor for each motor may not be the same value. For example, when a plurality of motors are rotating at 3000 rpm (50 Hz), the rotational frequency of one motor can be set to 2900 rpm (48.3 Hz) to obtain different angular frequencies of electrical angles.

  As described above, in the second embodiment, when the axis specifying operation command generating unit 13i is specified by the insulation deterioration axis specifying unit 12 that there are two or more motors operating at the same angular frequency, two or more An axis specifying operation command is issued to one or more of the two or more motors so that the motors operate at different angular frequencies. Thereby, even when there are a plurality of axes that operate at an angular frequency of the same electrical angle, it is possible to specify an insulation deterioration axis.

  In the second embodiment, the axis specifying operation command is, for example, a frequency component other than a frequency that is an integral multiple of the commercial power supply frequency, or a frequency other than an integer multiple of the angular frequency of the electrical angle of the rotating AC motor. This command includes frequency components. As a result, when there are two or more motors operating at the same angular frequency, it is easy to issue an axis specifying operation command so that the two or more motors operate at different angular frequencies.

  In the second embodiment, the axis specifying operation command is superposed on any of the D axis current, Q axis current, speed, and position commands, or the D axis current, Q axis current, speed, This is a command to change any command of position. As a result, when there are two or more motors operating at the same angular frequency, it is easy to issue an axis specifying operation command so that the two or more motors operate at different angular frequencies.

  As described above, the insulation deterioration diagnosis device according to the present invention is useful for diagnosis of insulation deterioration with respect to a plurality of axes.

DESCRIPTION OF SYMBOLS 10 Insulation deterioration diagnostic apparatus 11 Frequency component classification part 12 Insulation deterioration axis | shaft specific part 20 Leakage current detection part 30 Angular frequency calculation part AC AC power supply AL1-ALn Current amplitude CV converter F1-Fn Angular frequency FL1-FLn Frequency component signal IL Leakage current INV-1 to INV-n Inverter M-1 to M-n Motor P1 to Pn Position information

Claims (4)

Calculated by the angular frequency calculation unit that calculates the angular frequency of the electrical angle of the plurality of motors from the leakage current detected by the leakage current detection unit that detects the leakage current flowing in the electric path between the plurality of motors and the power source. A frequency component separation unit for separating a plurality of frequency components corresponding to a plurality of angular frequencies;
Among the plurality of axes corresponding to the plurality of motors, the one with the current amplitude in the plurality of separated frequency components larger than the threshold is extracted, and the axis corresponding to the extracted frequency components is specified as the insulation deterioration axis. An insulation deterioration axis identifying part;
An insulation deterioration diagnosis device characterized by comprising: One of the two or more motors is operated so that the two or more motors operate at different angular frequencies when the insulation deterioration axis specifying unit specifies that there are two or more motors operating at the same angular frequency. The insulation deterioration diagnosis apparatus according to claim 1, further comprising: an axis specifying operation command generation unit that issues an axis specifying operation command to the motor. The axis specifying operation command is a command including a frequency component other than an integer multiple of the commercial power supply frequency or a frequency component other than an integer multiple of the angular frequency of the electrical angle of the rotating AC motor. The insulation deterioration diagnosis apparatus according to claim 2, wherein The axis specifying operation command is a command to be superimposed on any of the D-axis current, Q-axis current, speed, and position commands, or any command of D-axis current, Q-axis current, speed, and position. The insulation deterioration diagnosis apparatus according to claim 2, wherein the instruction is a command to be changed.

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