JP2013221843A - Failure detection device and failure detection method for multiaxial three-phase servo motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a failure detection device and a failure detection method for a multiaxial three-phase servo motor, which require no A/D converter, and perform failure detection for respective three-phase servo motors with a small number of components, and moreover enable correct failure determination in the failure detection.SOLUTION: One electric conduction detection circuit part (330) is used for applying a DC voltage between winding circuits of respective three-phase servo motors and the earth, and failure detection of the three-phase servo motors is performed based on current flowing through the electric conduction detection circuit part (330).

Description

  The present invention relates to a failure detection apparatus and a failure detection method for a multi-axis three-phase servomotor for detecting a failure of a three-phase servomotor with high accuracy while suppressing an increase in the number of parts.

  As a method for detecting a failure of a three-phase servo motor, a conventional technique using an instantaneous value of a three-phase phase voltage and an instantaneous value of a phase current is known (for example, Patent Document 1).

  The fault detection device for a three-phase inverter as shown in Patent Document 1 is configured to provide an instantaneous value of a three-phase phase voltage and an instantaneous value of a phase current in a three-phase inverter via a sample hold circuit and a detection target switching unit. An analog value is converted into a digital value by an A / D converter.

  Next, the addition value of the phase voltage and the addition value of the phase current of each phase after conversion into a digital value are calculated by the microprocessor. When each added value is close to 0, it is determined as “normal”, and when it deviates from near 0, it is determined as “abnormal” to detect a failure.

Japanese Patent No. 2902455

However, the prior art has the following problems.
The failure detection apparatus as shown in Patent Document 1 requires a high-speed and high-precision A / D converter in order to measure a rectangular inverter output voltage waveform. Furthermore, in a system in which a plurality of servo motors are combined, a failure detection circuit is required for each motor, so a large number of component configurations are required. As a result, there has been a problem that the apparatus cost becomes high.

  Also, in a system that combines multiple servo motors, due to the influence of induced current or leakage current, accurate failure determination cannot be performed, or when the neutral point of the receiving transformer is ungrounded or high resistance grounding, There was also a problem of reliability that an accurate failure judgment could not be made.

  The present invention has been made to solve the above-described problems, and does not require an A / D converter, detects a failure with a small number of components, and further performs an accurate failure determination in the failure detection. An object of the present invention is to obtain a failure detection apparatus and failure detection method for a multi-axis three-phase servo motor.

  The failure detection device for a multi-axis three-phase servo motor according to the present invention is a failure detection device for a multi-axis three-phase servo motor that performs failure detection of a plurality of three-phase servo motors with a single device. A DC power supply for applying a DC voltage for fault diagnosis to the winding circuit of a certain three-phase servo motor, and detecting whether a current exceeding a predetermined value flows through the winding circuit when a DC voltage is applied Are connected between the energization detection circuit unit and the winding circuit of each of the plurality of three-phase servo motors, and based on the switching command from the outside, A detection target switching unit that enables selection and switching of a winding circuit to which a DC voltage is applied from among the line circuits, and each drive output unit of a plurality of three-phase servo motors when detecting a failure of a three-phase servo motor After stopping the operation In order to identify the three-phase servo motor that is the target of failure detection from multiple three-phase servo motors, a switching command is output to the detection target switching unit, and failure detection is performed based on the measurement results of the current detection unit. A failure determination unit that determines that a ground fault has occurred in the three-phase servo motor that is a failure detection target when it is determined that a current of a predetermined value or more has flowed through the winding circuit of the target three-phase servo motor. It is to be prepared.

  The failure detection method according to the present invention is a failure detection method executed by a failure detection apparatus for a multi-axis three-phase servo motor that performs failure detection of a plurality of three-phase servo motors by one unit. The first step of stopping the operation of each drive output unit of the three-phase servo motor, and the winding circuit of the three-phase servo motor that is a failure detection target from among the respective winding circuits of the plurality of three-phase servo motors The second step of applying a DC voltage for fault diagnosis to the selected winding circuit and the detection of whether or not a current of a predetermined value or more flows through the winding circuit when the DC voltage is applied. If it is determined that a current greater than or equal to a predetermined value has flowed through the winding circuit of the three-phase servo motor that is the failure detection target based on the detection result of the third step and the third step, Phase servo motor In which and a fourth step of determining a ground fault occurs in data.

  According to the failure detection apparatus and the failure detection method for a multi-axis three-phase servo motor in the present invention, a DC voltage is applied between the winding circuit of each three-phase servo motor and the ground using one energization detection circuit unit. In addition, by performing failure detection using the current flowing through the energization detection circuit unit, it is possible to perform failure detection with a small number of components without requiring an A / D converter, and to perform accurate failure determination. A failure detection apparatus and failure detection method for a multi-axis three-phase servomotor can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram when applying the failure detection apparatus for three-phase servomotors in Embodiment 1 of this invention to a system. It is a block diagram when applying the failure detection apparatus for a three-phase servo motor in Embodiment 2 of the present invention to a system using one three-phase servo motor. It is a block diagram of the electricity supply detection circuit part in Embodiment 3 of this invention. It is a block diagram of the electricity supply detection circuit part in Embodiment 4 of this invention.

  Hereinafter, preferred embodiments of a failure detection apparatus and failure detection method for a multi-axis three-phase servo motor according to the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram when a failure detection apparatus for a three-phase servo motor according to Embodiment 1 of the present invention is applied to a system. FIG. 1 shows an example of a configuration in which one failure detection device is applied to a system that drives eight three-phase servo motors.

  The system in FIG. 1 includes a drive output unit (three-phase inverter unit) 100 for a three-phase servo motor, a three-phase servo motor unit 200, and a failure detection device 300.

  The drive output unit 100 includes drive output circuits 101 to 108 corresponding to each of the eight three-phase servo motors as illustrated. The three-phase servo motor unit 200 includes three-phase servo motors 201 to 208.

  The failure detection apparatus 300 includes a high voltage isolation circuit unit 310, a detection target switching unit 320, an energization detection circuit unit 330, and a failure determination unit 340. The energization detection circuit unit 330 includes a DC power source 331 and a current detection unit 332.

  The high voltage isolation circuit unit 310 includes circuit open / close units 311 to 318 that can open and close each of the three-phase servo motors 201 to 208 as illustrated. In addition, the detection target switching unit 320 includes circuit selection units 321 to 328 that can individually select the three-phase servomotors 201 to 208, respectively.

  The high voltage isolation circuit unit 310 is installed between the three-phase servo motor unit 200 and the detection target switching unit 320 as illustrated. The high voltage isolation circuit unit 310 connects or disconnects them as necessary.

  The detection target switching unit 320 switches from the failure determination unit 340 to select one of the three-phase servomotors 201 to 208 as the three-phase servomotor that is the target of failure detection in the three-phase servomotor unit 200. Select and switch according to the command.

  The energization detection circuit unit 330 applies a DC voltage for fault diagnosis between the winding circuit of the three-phase servo motor and the ground by the DC power source 331 with respect to one selected three-phase servo motor. The current detection unit 332 detects whether or not a current of a predetermined value or more flows through the winding circuit when a DC voltage is applied.

  The failure determination unit 340 stops driving output of the driving output unit 100 by a driving control unit (not shown), opens and closes by the high voltage isolation circuit unit 310, selection by the detection target switching unit 320, and DC voltage by the energization detection circuit unit 330. By controlling each of the application and current detection, failure determination of each of the three-phase servomotors 201 to 208 in the three-phase servomotor unit 200 is performed.

  Here, the failure detection apparatus for the multi-axis three-phase servo motor in the first embodiment has the following technical features as compared with the prior art.

[First Technical Feature] Superiority in Cost The failure detection apparatus 300 according to the first embodiment does not require a high-speed and high-precision A / D converter. Furthermore, as illustrated in FIG. 1, by providing the detection target switching unit 320 in the failure detection device 300, only one energization detection circuit unit 330 (failure detection circuit) may be provided as the entire system. Accordingly, the component configuration can be minimized. As a result, it is superior in cost compared with the prior art.

[Second Technical Feature] High Reliability The failure detection apparatus 300 according to the first embodiment applies a DC voltage between the winding circuit of the three-phase servomotor and the ground, and the current flowing through the energization detection circuit unit 330 Failure is being judged. For this reason, even when the neutral point of the power receiving transformer is ungrounded or high-resistance grounded without being affected by an induced current or a leakage current, an accurate failure determination can be performed. As a result, a highly reliable system can be realized as compared with the prior art.

  Next, a series of operations in which the failure detection apparatus 300 detects a failure of the three-phase servo motor will be specifically described. Here, a case where the current detection unit 332 in the energization detection circuit unit 330 is configured by a small relay 333 will be described.

  First, the failure determination unit 340 in the failure detection apparatus 300 causes the drive control unit (not shown) to stop the operation of the drive output unit 100. In this case, all the gates of the inverter output circuit of the drive output unit 100 are turned off, and the output voltage to each of the three-phase servomotors 201 to 208 in the three-phase servomotor unit 200 is 0V.

  Next, the failure determination unit 340 closes the circuit open / close units 311 to 318 in the high voltage isolation circuit unit 310 in a closed state so that a gap between the three-phase servo motor unit 200 and the detection target switching unit 320 is established. Connecting.

  In addition, when the drive output unit 100 is in operation, the circuit open / close units 311 to 318 in the high voltage isolation circuit unit 310 are provided to protect the energization detection circuit unit 330 from a rectangular high voltage drive voltage. It is open all at once. That is, the three-phase servo motor unit 200 and the detection target switching unit 320 are disconnected.

  Next, in order to select the three-phase servo motor that performs failure detection in the three-phase servo motor unit 200, the failure determination unit 340 is a circuit in the detection target switching unit 320 corresponding to the three-phase servo motor that performs failure detection. Any one of the selectors 321 to 328 is selected and closed.

  When the circuit selection unit corresponding to the three-phase servo motor that performs failure detection is closed, the three-phase servo motor that is a failure detection target and the energization detection circuit unit 330 are connected, and failure determination can be performed.

  Then, the failure determination unit 340 sequentially closes (selects and switches) the circuit selection unit corresponding to the three-phase servo motor that performs failure detection, thereby determining the failure determination of all three-phase servo motors in the system. This can be done with one unit.

  Next, a specific failure detection method will be described with reference to an example in which failure determination of the first three-phase servomotor 201 is performed. The same applies to the second and subsequent three-phase servo motors (three-phase servo motors 202 to 208).

  First, the failure determination unit 340 causes a drive control unit (not shown) to stop the operation of the drive output unit 100 to detect the failure, and collects the circuit open / close units 311 to 318 in the high voltage isolation circuit unit 310 collectively. To the closed state. Then, the failure determination unit 340 closes only the circuit selection unit 321 corresponding to the first three-phase servomotor 201. At this time, the other circuit selection units 322 to 328 are in an open state.

  As a result, the three-phase servo motor 201 and the energization detection circuit unit 330 are connected. A DC voltage is applied between the three-phase servo motor 201 and the ground by the DC power source 331 in the energization detection circuit unit 330.

  Further, the small relay 333 in the energization detection circuit unit 330 is turned on when a current of a predetermined value or more (for example, about 10 mA) flows through the energization detection circuit unit 330 by application of a DC voltage, and is turned off when it does not flow. It becomes a state.

  If a part of the winding circuit or wiring of the three-phase servo motor 201 is short-circuited to the frame or the like when a DC voltage is applied, a circuit is formed via the ground, such as a part of the winding circuit or wiring, the frame, or the like. Therefore, a current of a predetermined value or more flows in the energization detection circuit unit 330, and the small relay 333 is turned on.

  Therefore, the failure determination unit 340 can determine that a failure such as a ground fault has occurred in the three-phase servo motor 201 and issue a warning when the small relay 333 is on. This warning is for notifying that the normal operation is not performed in order to protect the three-phase servo motor 201 determined to be malfunctioning.

  On the other hand, if a fault such as a ground fault has not occurred in the three-phase servo motor 201 when a DC voltage is applied, a current exceeding a predetermined value does not flow in the energization detection circuit unit 330, and the small relay 333 is in an OFF state. It becomes. Therefore, the failure determination unit 340 determines that the three-phase servo motor 201 is normal when the small relay 333 is in the off state.

  The winding circuit of the three-phase servo motor 201 has inductance, but since a DC voltage is applied, the impedance in the circuit is almost 0 ohms. Therefore, the failure determination unit 340 is not affected by the inductance of the winding circuit, and performs an accurate failure determination according to the current value even if a failure such as a ground fault occurs in any of the three-phase windings. be able to.

  In addition, after the failure determination unit 340 determines the failure of the first three-phase servomotor 201, only the circuit selection units 322 to 328 corresponding to the second and subsequent three-phase servomotors 202 to 208 are sequentially sequentially changed. By making the closed state, it is possible to make a failure determination for all the three-phase servomotors 201 to 208 with one unit.

  The failure determination unit 340 determines the failure of all the three-phase servo motors 201 to 208 in the three-phase servo motor unit 200 in this way, and then collectively sets the circuit open / close units 311 to 318 in the high voltage isolation circuit unit 310. Open. As a result, the three-phase servo motor unit 200 and the detection target switching unit 320 are disconnected. Thereafter, the three-phase servo motor determined to be normal can be normally operated by the corresponding drive output circuits 101 to 108.

  As described above, according to the first embodiment of the present invention, in a system in which a plurality of three-phase servo motors are combined, the energization detection circuit unit is configured as a whole system by performing selection switching by the detection target switching unit. You only need one. Furthermore, it is possible to make a failure determination by applying a DC voltage between the winding circuit of the three-phase servo motor and the ground and using a current flowing through the energization detection circuit unit.

  Thereby, a high-speed and highly accurate A / D converter is not required, and the component configuration can be minimized. Furthermore, an accurate failure determination can be made even when the neutral point of the power receiving transformer is ungrounded or high-resistance grounded without being affected by an induced current or a leakage current.

  In the first embodiment, the failure detection apparatus 300 can obtain the same effect without the high voltage isolation circuit unit 310. In addition, as a device constituting the current detection unit 332, another device other than the small relay 333 may be used as long as it is a device that detects a current exceeding a predetermined value flowing in the circuit.

Embodiment 2. FIG.
In the first embodiment, the failure detection apparatus 300 applied to a system (large-scale system) in which a plurality of three-phase servo motors are combined has been described. On the other hand, in Embodiment 2 of the present invention, a failure detection apparatus 300 applied to a system (small system) using one three-phase servo motor will be described.

  FIG. 2 is a configuration diagram when the failure detection apparatus 300 for a three-phase servo motor in Embodiment 2 of the present invention is applied to a system using one three-phase servo motor. The system in FIG. 2 includes a drive output unit 100, a three-phase servo motor unit 200, and a failure detection device 300.

  The drive output unit 100 has one drive output circuit 101 as shown in the figure. The three-phase servo motor unit 200 has a single three-phase servo motor 201 driven by one drive output circuit 101.

  The failure detection apparatus 300 includes a high voltage isolation circuit unit 310, an energization detection circuit unit 330, and a failure determination unit 340. As shown in the figure, the high voltage isolation circuit unit 310 includes a circuit opening / closing unit 311 corresponding to the three-phase servo motor 201 and is limited to one circuit. In addition, the energization detection circuit unit 330 includes a DC power source 331 and a small relay 333 as in the first embodiment.

  Further, unlike the first embodiment, the detection target switching unit 320 is not provided. That is, since the failure detection apparatus 300 in FIG. 2 is applied to a system using a single three-phase servo motor, the failure detection apparatus 300 includes only the high voltage isolation circuit unit 310 without including the detection target switching unit 320. Thus, the same effect can be obtained. Since a series of operations for detecting a failure of the three-phase servo motor 201 is the same as that in the first embodiment, the description thereof is omitted.

  Further, in the case of a system using a single three-phase servomotor, since there is no switching by the detection target switching unit 320 in the failure detection apparatus 300, a failure can be detected easily in a short time.

  As described above, according to the second embodiment of the present invention, in the system using one three-phase servo motor, the circuit open / close unit in the failure detection apparatus is limited to one circuit, and further, the detection target switching unit is not provided. It is possible to make a failure determination. As a result, the number of components can be reduced, and the operation time of the detection target switching unit is omitted, so that accurate failure determination can be performed easily in a short time.

  In the second embodiment, the failure detection apparatus 300 includes a detection target switching unit 320 in which the circuit selection unit is limited to one circuit instead of the high voltage isolation circuit unit 310 in which the circuit opening / closing unit is limited to one circuit. However, the same effect can be obtained.

Embodiment 3 FIG.
In the first and second embodiments, the failure detection method using the energization detection circuit unit 330 having the small relay 333 has been described. On the other hand, in the third embodiment of the present invention, a failure detection apparatus 300 including an energization detection circuit unit 330 having a configuration different from those of the first and second embodiments will be described.

  FIG. 3 is a configuration diagram of the energization detection circuit unit 330 according to the third embodiment of the present invention. The energization detection circuit unit 330 in FIG. 3 includes a DC power source 331 as well as the energization detection circuit unit 330 in FIGS. 1 and 2, and includes a shunt resistor 334 and a current measuring device 335 in place of the small relay 333. Prepare.

  The shunt resistor 334 in the energization detection circuit unit 330 is inserted in series between the detection target switching unit 320 and the DC power source 331, and the current measuring device 335 measures the value of the current flowing through the shunt resistor 334. .

  Next, the failure detection apparatus 300 including the energization detection circuit unit 330 in FIG. 3 will be described. The failure detection apparatus 300 according to the third embodiment is different in the configuration of the energization detection circuit unit 330 of the failure detection apparatus 300 in FIGS. 1 and 2, and the other components are the same.

  Therefore, here, the operation of the energization detection circuit unit 330 according to the third embodiment will be mainly described. The failure detection apparatus 300 for a multi-axis three-phase servo motor according to the third embodiment has a technical feature of performing failure determination by measuring a change in current value in a circuit with time.

  That is, in the energization detection circuit unit 330 in the first and second embodiments, whether or not a current of a predetermined value or more flows in the circuit by detecting the binary value (on state / off state) of the small relay 333. The failure was determined for the three-phase servo motor.

  On the other hand, the energization detection circuit unit 330 according to the third embodiment accurately measures the current value in the circuit and confirms the change with time of the current value flowing in the circuit, so that the three-phase servo motor Failure determination can be performed with higher accuracy.

  For example, the current value is measured every week, and the data is plotted with the elapsed time on the horizontal axis and the current value on the vertical axis for the measured data. The shape of the graph thus obtained makes it possible to check how the current value changes over time every week, and the state of the three-phase servo motor with time can be understood.

  In addition, as a criterion for judging a failure of a three-phase servo motor, for example, when the slope obtained by linear approximation of the data in the graph becomes a certain value or more, or when the current value becomes more than a predetermined threshold value In addition, the failure determination unit 340 can determine whether or not a ground fault has occurred based on the measurement results over time by the energization detection circuit unit 330.

  As described above, according to the third embodiment of the present invention, an energization detection circuit unit having a shunt resistor and a current measuring device is provided instead of the small relay, and a change with time of the current value flowing in the circuit is confirmed. Therefore, failure detection is performed. This makes it possible to detect a failure with higher accuracy and stop the three-phase servo motor compared to the first and second embodiments where the failure was detected based on the ON / OFF state of the small relay. An abnormal condition can be determined before a serious accident.

Embodiment 4 FIG.
In the third embodiment, the failure detection apparatus 300 including the energization detection circuit unit 330 including the shunt resistor 334 and the current measuring device 335 has been described. On the other hand, in the fourth embodiment of the present invention, a failure detection apparatus 300 including an energization detection circuit unit 330 having a configuration different from that of the third embodiment will be described.

  FIG. 4 is a configuration diagram of the energization detection circuit unit 330 according to the fourth embodiment of the present invention. 4 includes a DC power source 331, a shunt resistor 334, and a current measuring device 335, as well as an AC power source 336, in the same manner as the energization detection circuit unit 330 in FIG.

  Next, the failure detection apparatus 300 including the energization detection circuit unit 330 in FIG. 4 will be described. The failure detection apparatus 300 according to the fourth embodiment is different in the configuration of the energization detection circuit unit 330 of the failure detection apparatus 300 in FIG. 3, and the other components are the same.

  Therefore, here, the operation of the energization detection circuit unit 330 according to the fourth embodiment will be mainly described. The failure detection apparatus 300 for a three-phase servo motor in the fourth embodiment further includes an AC power source 336, so that the AC current is superimposed on the DC current and the inductance of the winding circuit of the three-phase servo motor is taken into account. Therefore, the technical feature is that the failure determination is performed.

  In the energization detection circuit unit 330 according to the fourth embodiment, the current value in the circuit is accurately measured, and the time-dependent change of the current value flowing in the circuit is confirmed, so that the failure determination is performed with higher accuracy. Can do. Further, by taking into account the inductance of the winding circuit of the three-phase servo motor, it is possible to estimate at which position of the winding the ground has occurred in the frame.

  For example, consider a case where a voltage is applied between the U phase of the winding circuit of a three-phase servo motor that is a failure detection target and the ground. In this case, if the magnitudes of the DC current value and the effective value of the AC current (hereinafter referred to as AC current values) are substantially equal in the circuit, it can be determined that the U phase is grounded in the frame.

  In the circuit, when the direct current value is larger than the alternating current value and the alternating current value is reduced by the inductance in the U phase, the neutral point portion or the connection between the U phase and the V phase It can be judged that there is a ground fault near the club.

  In this way, by comparing the magnitudes of the direct current value and the alternating current value, it is possible to estimate at which position of the winding circuit the ground is in the frame (location of occurrence of the ground fault).

  Note that the failure determination unit 340 is configured to apply the voltage obtained by superimposing the DC voltage and the AC voltage between the U phase and the ground of the winding circuit and measure the current in the circuit using the current measuring device 335. It becomes possible to read the measurement result of the alternating current value and the direct current value. As a result, component parts can be reduced as a whole system.

  The same effect can be obtained when a voltage is applied between the V phase or W phase of the winding circuit of the three-phase servomotor and the ground.

  As described above, according to the fourth embodiment of the present invention, the value of the direct current flowing in the circuit is compared with the value of the alternating current using the energization detection circuit unit provided with the alternating current power supply in addition to the direct current power supply. And fault detection is performed. Thereby, in addition to the presence or absence of a ground fault, it is possible to estimate at which position of the winding circuit the ground is in the frame.

  DESCRIPTION OF SYMBOLS 100 Drive output part, 101-108 Drive output circuit, 200 Three-phase servo motor part, 201-208 Three-phase servo motor, 300 Fault detection device, 310 High voltage isolation circuit part, 311-318 Circuit opening / closing part, 320 Detection object switching Unit, 321-328 circuit selection unit, 330 energization detection circuit unit, 331 DC power supply, 332 current detection unit, 333 small relay, 334 shunt resistance, 335 current measurement device, 336 AC power supply, 340 failure determination unit.

Claims (6)

A failure detection device for a multi-axis three-phase servo motor that detects a failure of a plurality of three-phase servo motors with one unit,
A DC power source for applying a DC voltage for fault diagnosis to the winding circuit of the three-phase servo motor that is a fault detection target, and when the DC voltage is applied, a current of a predetermined value or more is applied to the winding circuit. An energization detection circuit unit having a current detection unit for detecting whether or not to flow;
Connected between the energization detection circuit unit and the respective winding circuits of the three-phase servo motors, and applies the DC voltage from the respective winding circuits based on an external switching command. A detection target switching unit that enables selective switching of a winding circuit to be performed;
When detecting the failure of the three-phase servo motor, after stopping the operation of the drive output unit of each of the plurality of three-phase servo motors, a failure detection target is selected from the plurality of three-phase servo motors. In order to identify a certain three-phase servomotor, the switching command is output to the detection target switching unit, and the winding of the three-phase servomotor that is the fault detection target based on the measurement result of the current detection unit A multi-axis three-way motor, comprising: a failure determination unit that determines that a ground fault has occurred in the three-phase servomotor that is the target of failure detection when it is determined that a current of a predetermined value or more has flowed through the circuit. Fault detection device for phase servo motor. In the failure detection apparatus for a multi-axis three-phase servo motor according to claim 1,
The current detection unit is configured by a small relay that is turned on when a current of a predetermined value or more flows through the winding circuit when the DC voltage is applied,
The failure determination unit determines that a ground fault has occurred in the three-phase servomotor that is the failure detection target when the small relay is in the on state. Failure detection device for motors. In the failure detection apparatus for a multi-axis three-phase servo motor according to claim 1,
The current detection unit includes a shunt resistor inserted in series between the detection target switching unit and the DC power source, and a current measuring device that measures a current value flowing through the shunt resistor,
The failure determination unit determines whether or not a ground fault has occurred in the three-phase servomotor that is the target of failure detection according to the magnitude of the DC current value measured by the current measuring instrument and the change over time. A failure detection device for a multi-axis three-phase servo motor characterized by: In the failure detection apparatus for a multi-axis three-phase servo motor according to claim 3,
The energization detection circuit unit further includes an AC power source for applying an AC voltage superimposed on the DC voltage for failure diagnosis to the winding circuit of the three-phase servo motor that is the target of failure detection,
The failure determination unit estimates the location of occurrence of the ground fault by comparing the effective value of the alternating current measured by the current measuring device and the magnitude of the direct current value. Failure detection device for multi-axis three-phase servo motor. In the failure detection apparatus for a multi-axis three-phase servomotor according to any one of claims 1 to 4,
It is connected between the detection target switching unit and the respective winding circuits of the plurality of three-phase servo motors, and when the failure detection of the three-phase servo motor is performed, it is collectively closed and the three-phase A failure detection apparatus for a multi-axis three-phase servo motor, further comprising a high voltage isolation circuit section that is collectively opened during normal operation of the servo motor. A failure detection method executed by a failure detection apparatus for a multi-axis three-phase servo motor that performs failure detection of a plurality of three-phase servo motors by one unit,
A first step of stopping operation of each drive output unit of the plurality of three-phase servomotors;
By selecting and switching the winding circuit of the three-phase servo motor that is the target of failure detection from among the respective winding circuits of the plurality of three-phase servo motors, a DC voltage for fault diagnosis is selected in the selected winding circuit. A second step of applying
A third step of detecting whether a current of a predetermined value or more flows through the winding circuit when the DC voltage is applied;
If it is determined that a current of a predetermined value or more has flowed through the winding circuit of the three-phase servomotor that is the failure detection target based on the detection result of the third step, the three-phase servomotor that is the failure detection target And a fourth step of determining that a ground fault has occurred.

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