JP2009033938A - Electric vehicle controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely detect a semiconductor failure due to a ground fault in a power converter caused, and prevent the spread of the failure in the power converter. <P>SOLUTION: A comparison circuit 23a compares a current value detected by current detectors 3, 4, which are provided on an AC motor output side of an inverter device 1, with a ground current detection set value IS1 and detects the ground fault of the AC motor side wiring in the inverter device 1 based on the comparison result. A fault detector unit 55a detects the fault of a semiconductor element 18 which constitutes the inverter device 1. When the comparison circuit 23a detects the ground fault and the fault detector unit 55a detects a fault at the same time, an open processing unit 24a disconnects the an overhead wire from the inverter device 1 with an electromagnetic contactor 9. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric vehicle control device that drives an AC motor by a power conversion device that converts power supplied from an overhead wire. For example, when the AC motor side wiring of the power conversion device has a ground fault, the power conversion device is disconnected from the overhead wire. The present invention relates to an electric vehicle control device that is separated and prevents an electric power converter from causing an extended failure due to a ground fault current.

  In an electric vehicle control device equipped with a power conversion device that converts power from an overhead wire, if an AC motor side wiring of the power conversion device has a ground fault, an excessive ground that flows from the overhead wire to the ground fault point via the power conversion device The fault current has caused a failure of the semiconductor element used in the power conversion device.

Therefore, conventionally, when a ground fault is detected, the operation of the power converter is stopped in order to prevent an extended failure of the power converter (Patent Documents 1 and 2).
JP 2002-159102 A JP-A-6-245301

  When a semiconductor element of the power converter fails due to a ground fault or other reasons, the failure is detected, a warning is displayed on the cab, and the power converter is stopped to prevent an extended failure of the power converter. Can do.

  Such an operation stop and warning display of the power converter is not limited to a semiconductor element failure due to a ground fault. For example, in order to protect the semiconductor element even when an input voltage (feed voltage) of the power converter is excessively increased. To be done. By accepting a reset command from the cab, it is possible to restart the operation of the power converter.

  From the cab, it cannot be determined whether or not the warning display is caused by a semiconductor element failure of the power conversion device, and therefore a reset operation may be performed immediately after the semiconductor element failure is detected. As a result, the operation of the power converter is resumed, and when a ground fault occurs, the ground fault current flows again into the power converter, and the ground fault current causes an extended failure.

  Therefore, an object of the present invention is to reliably detect a semiconductor failure of a power conversion device due to a ground fault and prevent an extended failure of the power conversion device.

  The present invention uses a current detector attached to the overhead wire input side or the AC motor side of the power conversion device in addition to the semiconductor element failure detection of the power conversion device, and the current value detected from the current detector is a predetermined value. It has a function to determine a ground fault when exceeding the limit, and when both a semiconductor element failure and a ground fault are detected, the power converter is automatically disconnected from the input overhead line and does not accept a reset command from the cab By adopting the configuration, an extended failure due to the power converter operating again is prevented.

  It is possible to reliably detect a semiconductor failure of the power conversion device due to a ground fault and prevent an extended failure of the power conversion device. In addition, after the ground fault occurs and the power conversion device stops, it is possible to prevent the power conversion device from restarting operation and expanding the failure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a first embodiment of an electric vehicle control apparatus according to the present invention.

  The voltage supplied from the pantograph 17 is subjected to noise removal by the filter reactors 11 and 12 and the filter capacitors 13 and 16 after passing through the electromagnetic contactors 9 and 10 and supplied to the positive input terminals of the inverter devices 1 and 2. The inverter devices 1 and 2 convert the input DC voltage into a three-phase AC voltage and drive the AC motors 7 and 8. The electromagnetic contactors 9 and 10 are opened in the event of an accident or vehicle failure, and cut off the power supply to the inverter devices 1 and 2. The negative input terminals of the inverter devices 1 and 2 pass through the input current detectors 15 and 16 and are grounded via wheels and rails (not shown).

  U-phase current detectors 3 and 5 and W-phase current detectors 4 and 6 are provided between the inverter devices 1 and 2 and the AC motors 7 and 8, and the detected current value is input to the comparison circuit 23a. . The comparison circuit (ground fault detection means) 23a is based on the current value detected by the U-phase current detectors 3 and 5 and the W-phase current detectors 4 and 6 and the ground fault current detection set value IS1 (described later). The ground fault detection signal GS1 is output.

  The inverter device 1 is configured by bridge-connecting a plurality of switching circuits each connecting a semiconductor element 18 and an antiparallel diode 20. In the inverter device 1, a plurality of semiconductor elements 18 are on / off controlled by a gate command signal from an inverter control circuit (not shown), and a three-phase AC voltage having a desired magnitude and frequency is generated. The failure detection unit 55a checks whether each semiconductor element 18 is normally on / off in accordance with the gate command signal. For example, the failure detection unit 55a fails a semiconductor element in which a malfunction occurs, such as when the semiconductor element is off, even though the gate command signal to the semiconductor element 18 indicates on. Judge. When there is such a failed semiconductor element, the failure detection unit 55a outputs a semiconductor element failure signal MS1 (for example, a high level signal) to the release processing unit 24a. The inverter device 2 is configured in the same manner as the inverter device 1. The failure detection unit 55b is configured in the same manner as the failure detection unit 55a, and determines that there is a failure when there is a malfunctioning semiconductor element 19 and outputs a semiconductor element failure signal MS2 to the release processing unit 24a.

  The opening processing unit 24a outputs opening command signals (for example, high level signals) OS1 and OS2 based on the semiconductor element failure signals MS1 and MS2 and the ground fault detection signal GS1. The electromagnetic contactor 9 is opened by the opening command signal OS1, and all the semiconductor elements 18 constituting the inverter device 1 are turned off. Further, the electromagnetic contactor 10 is opened by the opening command signal OS2, and all of the plurality of semiconductor elements 19 constituting the inverter device 2 are turned off.

  Next, the ground fault current detection set value will be described.

  The ground fault current detection set value is a current reference value for determining whether or not a ground fault has occurred. When a current flows exceeding the ground fault current detection set value, it is determined that a ground fault has occurred. For example, when a ground fault occurs between the inverter device and the AC motor, the output side inductance and resistance component of the inverter device are only due to the wiring between the inverter device and the ground fault point.

  When a ground fault occurs and a semiconductor element failure is detected, the ground fault current I flowing into the current detector is the potential difference E between the DC input voltage of the inverter device and the ground fault point, the output side wiring or the AC motor winding. Using the inductance L, the resistance component R, and the time t until the semiconductor element failure is detected, the following equation (1) is obtained.

I = E / R (1−ε− ^{(R / L) * t} ) (1)
That is, in the conventional circuit as shown in FIG. 2, a ground fault is experimentally generated like the ground fault point 22, and the resistance component R and the inductance L of each wiring are measured. The measured R and L are substituted into the ground fault current formula (1) to estimate the ground fault current characteristics. For example, when a current of 1000 A is estimated at t = 10 μsec from this current characteristic, the ground fault current detection set value is set to 1000 A. Thus, the ground fault current detection set value when a ground fault occurs between the inverter device and the AC motor is determined.

  Next, the operation relating to the first embodiment of the electric vehicle control apparatus shown in FIG. 1 will be described.

  For example, when a ground fault occurs in any phase wiring between the inverter device 1 and the AC motor 7, a large current is detected from the U-phase current detector 3 or the W-phase current detector 4. The comparison circuit 23a compares the detected large current with the ground fault current detection set value IS1, and detects the occurrence of a ground fault when a large current exceeding the set value IS1 flows. When a ground fault occurs, the semiconductor element 18 of the inverter device 1 generally fails, and the release processing unit 24a inputs the element failure signal MS1 and stops the inverter device 1.

  In other words, the comparison circuit 23a determines that any one of the current values detected by the U-phase current detectors 3 and 5 and the W-phase current detectors 4 and 6 exceeds the ground fault current detection set value IS1. The ground fault detection signal GS1 (for example, a high level signal) is output. Upon receiving the ground fault detection signal GS1, the opening processing unit 24a stops the inverter device outputting the semiconductor element failure signal MS1 or MS2 (drops all gate signals to a low level), and the corresponding electromagnetic contactor 9 Or let 10 be an open state.

  As described above, when the ground fault detection by the U-phase current detector or the W-phase current detector and the element failure are detected at the same time, the opening processing unit 24a opens the corresponding electromagnetic contactor, and the failed inverter device is connected from the DC input side. Automatically opened.

  With such a configuration, for example, when a ground fault occurs between the inverter device 1 and the AC motor 7, the inverter device 1 is automatically opened, the inverter device 1 is restarted (described later), and an extended failure occurs. Can be prevented.

(Second embodiment)
FIG. 3 is a block diagram showing the configuration of the second embodiment of the electric vehicle control apparatus according to the present invention. In the second embodiment, the ground fault is detected based on the input current value of the inverter device.

  Similar to the first embodiment, for example, when a ground fault occurs between the inverter device 1 and the AC motor 7, a large current is detected from the input current detector 15. The comparison circuit 23b compares the detected large current with the ground fault current detection set value IS2, and detects a ground fault when a large current exceeding the set value IS2 flows. When a ground fault occurs, the semiconductor element 18 of the inverter device 1 generally fails, and the release processing unit 24b detects the semiconductor element failure and stops the inverter device 1.

  That is, when a ground fault occurs, the comparison circuit 23b outputs a ground fault detection signal GS2 (for example, a high level signal) when the current value detected by the current detector 15 is larger than the ground fault current detection set value IS2. When the current value detected by the current detector 16 is larger than the ground fault current detection set value IS2, the ground fault detection signal GS3 is output.

  The release processing unit 24b outputs the logical product (AND) of the ground fault detection signal GS2 and the semiconductor element failure signal MS1 as the release command signal OS1, and outputs the logical product of the ground fault detection signal GS3 and the semiconductor element failure signal MS2 to the release command signal OS2. Output as.

  Therefore, when the ground fault detection by the input current detector 15 or 16 and the failure of the semiconductor element are detected at the same time, the open processing unit 24b opens the corresponding electromagnetic contactor, and all the gate signals of the failed inverter device are lowered to a low level and the operation is performed. Stop.

  By adopting such a configuration, it can be determined that a ground fault has occurred between the AC output of the inverter device and the AC motor even from an input current detector provided on the DC input side of the inverter device. The failed inverter device is automatically opened, and it is possible to prevent the inverter device from restarting and expanding.

(Third embodiment)
FIG. 4 is a block diagram showing the configuration of a third embodiment of the electric vehicle control apparatus according to the present invention. In the third embodiment, a configuration for detecting a ground fault based on an input current value and an output current value of an inverter device, and specific examples of the comparison circuit 23 and the open processing unit 24 will be described.

  The comparators 30a to 30d and the logical sum circuits 31a and 31b constitute a comparison circuit 23c. The logical product circuits 32a and 32b, the SR flip-flops 35a and 35b, the inverting circuits 53a and 53b, and the logical product circuits 54a and 54b 24c is configured.

  The comparators 30a and 30c compare the input currents of the inverter devices 1 and 2 with the ground fault current detection set value IS2, respectively, and detect the current exceeding the ground fault current set value IS2 to the OR circuits 31a and 31b. Outputs a ground fault detection signal. The comparators 30b and 30d respectively compare the output currents of the inverter devices 1 and 2 with the ground fault current detection set value IS1, and when a current exceeding the ground fault current set value IS1 is detected, to the OR circuits 31a and 31b. Outputs a ground fault detection signal.

  The ground fault can be detected independently on the inverter device 1 side and the inverter device 2 side. For example, when the ground fault is detected on the inverter device 1 side (OR circuit 31a output: high level) and the semiconductor element failure signal MS1 is output at the same time, the SR flip-flop 35a is set by the AND circuit 32a, and the open command signal OS1 is output.

  Thus, when the SR flip-flop 35a is set and a high level signal is output from the output terminal Q, the reset terminal R side of the SR flip-flop 35a is held at the low level by the inverting circuit 53a and the AND circuit 54a. Is done. As a result, the SR flip-flop 35a does not accept or invalidate the cab reset, so that the release command OS1 is not cleared. This operation is the same for the inverter device 2 side. That is, when both a ground fault and a semiconductor failure are detected (logical product circuit 32b output: high level), the SR flip-flop 35b is set and the release command OS2 is output. Not cleared when entered.

  When the release command OS1 is output, the semiconductor element 18 is turned off and the inverter device 1 is stopped. Further, the electromagnetic contactor 9 is opened, and the inverter device 1 is disconnected from the DC input side overhead wire. Similarly, when the release command S2 is output, the semiconductor element 19 is turned off and the inverter device 2 is stopped. Further, the electromagnetic contactor 10 is opened, and the inverter device 2 is disconnected from the DC input side overhead wire.

  Thus, according to the present embodiment, when a ground fault and a semiconductor failure are detected, the inverter device is automatically disconnected from the overhead wire on the DC input side, and then the release command is not reset by the cab reset signal. Restart of the inverter device can be prevented. Therefore, it is possible to prevent an extended failure of the semiconductor elements constituting the inverter device.

(Fourth embodiment)
FIG. 5 is a block diagram showing the configuration of a fourth embodiment of the electric vehicle control apparatus according to the present invention. The fourth embodiment is an electric vehicle control device applied to an AC feeding system. That is, the electric vehicle control device includes a converter device 36 that converts AC power from the pantograph 17 into DC power, and an inverter device 37 that drives the AC motor 47 by converting the DC output of the converter device 36 to AC.

  Based on the current values detected from the AC current detector 40, the DC current detector 41, and the inverter output current detector 42, when the AC motor 47 is driven by the inverter device 37, the AC motor 47 is switched from the converter device 36. The ground fault occurring between the first and third embodiments is detected by the same method as in the first to third embodiments. When a ground fault occurs, the semiconductor element 48 of the converter device 36 and the semiconductor element 50 of the inverter device 37 fail, and when the failure is detected, the converter device 36 and the inverter device 37 are stopped.

  That is, the comparison circuit 23d compares the current value detected by the AC current detector 40, the DC current detector 41, and the inverter output current detector 42 with the ground fault current detection set value IS3, and the ground fault current detection set. When a current value larger than the value IS3 is detected, a corresponding ground fault detection signal GS4, GS5 or GS6 is output. When the release processing unit 24d receives one of the ground fault detection signals GS4 to GS6 and the semiconductor element failure signal MSC or MSI at the same time, it outputs the release command signal OS3. As a result, the electromagnetic contactor 38 is opened, all the semiconductor elements 48 and 50 are turned off, and the converter device 36 and the inverter device 37 are stopped.

  As described above, when the ground fault detection by the AC current detector 40, the DC current detector 41 or the inverter output current detector 42 and the semiconductor element failure are detected at the same time, the open processing unit 24d opens the electromagnetic contactor 38, thereby converting the converter device. 36 and the inverter device 37 are stopped, and reset from the driver's cab is not accepted thereafter as described with reference to FIG.

  According to the fourth embodiment, the AC current detector 40 can determine a ground fault occurring between the DC side output of the converter device 36 and the AC motor 47, and the DC current detector 41 and the inverter output current detector 42 can be determined. Thus, a ground fault generated between the output of the inverter device 37 and the AC motor 47 can be detected. When a ground fault is detected, the converter device 36 and the inverter device 37 are automatically opened, and an extended failure due to restart can be prevented.

  In this embodiment, the power conversion device including the converter device and the inverter device is configured to drive one AC motor. However, a plurality of power conversion devices each including the converter device and the inverter device are a plurality of AC motors. May be configured to drive each. In that case, each power converter is provided with current detectors 40, 41, and 42 as in FIG. 5, and the comparison circuit compares the current value detected by each current detector with the ground fault current detection set value IS1. Then, the release processing unit independently shuts off the overhead wire and each power converter based on the detection results of the comparison circuit and the plurality of failure detection units.

(5th Example)
FIG. 6 is a diagram showing the concept of the fifth embodiment of the present invention.

  In the fifth embodiment, a plurality of ground fault current detection set values IS4 to IS6 are output from the control software unit 29 of the electric vehicle control device to the comparison circuit. The control software unit 29 can set the plurality of ground fault current detection set values IS4 to IS6 to arbitrary values.

  FIG. 7 shows a configuration in which the fifth embodiment is applied to the electric vehicle control apparatus shown in FIG.

  From the control software unit 29, the input side ground fault current detection set value IS4 and the output side ground fault current detection set value IS5 of the inverter device 37 can be set to arbitrary values. Further, from the control software unit 29, the input side ground fault current detection set value IS6 of the converter device 36 can be set to an arbitrary value.

  Further, the fifth embodiment can be applied to the electric vehicle control device shown in FIG. 1 or FIG. 3 so that the ground fault current set values IS1 and IS2 can be arbitrarily set. In that case, when the detection set values other than the ground fault detected by the U-phase current detectors 3 and 5, the W-phase current detectors 4 and 6, and the input current detectors 15 and 16 are changed, the comparison circuit 23 a, The ground fault current detection set value can be arbitrarily changed without changing the hardware of 23b. The detection setting value other than the ground fault is, for example, an overcurrent protection current setting value for protecting the inverter device or the converter device. That is, in the overcurrent protection circuit (not shown), for example, the U-phase current and W-phase current overcurrent protection current set values are initially set to 800A, and the ground fault current detection set value is set to 900A. However, when the overcurrent protection current set value is changed to 900A for reasons such as changing the AC motor, the ground fault current set value can be easily changed to a value such as 1100A.

(Sixth embodiment)
FIG. 8 is a block diagram showing the configuration of the sixth embodiment of the electric vehicle control apparatus according to the present invention. The sixth embodiment uses the U-phase current detectors 3 and 5, the W-phase current detectors 4 and 6, and the inverter output current detector 42 of FIG. 1 or FIG. 5, and the semiconductor elements 18, 19, and 50 fail. Therefore, the AC motor is protected from overcurrent by detecting a current value lower than the ground fault current detection set value.

  The comparison circuit 23f has a current detection value obtained from the U-phase current detectors 3 and 5 in FIG. 1, the W-phase current detectors 4 and 6, or the inverter output current detector 42 in FIG. When the set value AMS is exceeded, an overcurrent detection signal GS7 (for example, a high level signal) is output. This AC motor overcurrent protection set value AMS is a value set based on the maximum allowable current value of the AC motor. When the overcurrent detection signal GS7 and the semiconductor element failure signal MS3 are input, the open processing unit 24f outputs an open command signal OS4. As a result, the operation of the inverter device and the converter device is stopped, and the corresponding electromagnetic contactor is opened. As described above, when the open circuit processing unit 24f detects the AC motor overcurrent detection signal GS7 and the semiconductor element failure signal MS3 at the same time, it opens the electromagnetic contactors 9, 10 or the electromagnetic contactors 38 and 39, and opens the inverter devices 1, 2 or The inverter device 36 and the converter device 36 are disconnected from the overhead line and automatically opened. This open state is not reset by the cab reset signal.

  That is, the sixth embodiment is equivalent to a configuration in which, for example, in the configuration of FIG. 1 or FIG. 5, the AC motor overcurrent protection set value is set in the comparison circuit instead of the ground fault current detection set value. By detecting the AC motor overcurrent instead of the ground fault current in this way, an inverter device and a conventional overcurrent protection circuit comparison circuit can be used without newly providing a comparison circuit for ground fault detection. The converter device can be opened.

  The above description is an embodiment of the present invention, and does not limit the apparatus and method of the present invention, and various modifications can be easily implemented.

The block diagram which shows the structure of 1st Example of the electric vehicle control apparatus by this invention. The block diagram which shows the conventional structure of the electric vehicle control apparatus used in order to obtain | require the current characteristic of a ground fault current. The block diagram which shows the structure of 2nd Example of the electric vehicle control apparatus by this invention. The block diagram which shows the structure of 3rd Example of the electric vehicle control apparatus by this invention. The block diagram which shows the structure of 4th Example of the electric vehicle control apparatus by this invention. The figure which shows the concept of 5th Example of this invention. The figure which shows the structure which applied 5th Example to the electric vehicle control apparatus shown in FIG. The block diagram which shows the structure of 6th Example of the electric vehicle control apparatus by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2 ... Inverter device, 3, 5 ... U-phase current detector, 4, 6 ... W-phase current detector, 7, 8 ... AC motor, 9, 10 ... Electromagnetic contactor, 11, 12 ... Filter reactor, 13 , 14 ... Filter capacitors, 15, 16 ... Input current detectors, 17 ... Pantographs, 18, 19 ... Semiconductor elements, 20, 21 ... Anti-parallel diodes, 23a-23f ... Comparison circuits, 24a-24f ... Opening processing unit, 29 ... control software section, 30a to 30d ... comparators, 31a and 31b ... OR circuits, 32a and 32b ... AND circuits, 35a and 35b ... SR flip-flops, 36 and 37 ... inverter devices, 38 and 39 ... electromagnetic contactors , 40 ... AC current detector, 41 ... DC current detector, 42 ... Inverter output current detector 42, 43 ... Filter reactor, 44 ... Filter capacitor, 47 AC motor, 48 ... semiconductor device, 49, 51 ... anti-parallel diode, 50 ... semiconductor device, 52 ... transformer.

Claims (10)

In the electric vehicle control device that converts the DC power supplied from the overhead line through the pantograph into AC power and drives the AC motor,
A power conversion device that includes a plurality of semiconductor elements as components and controls the plurality of semiconductor elements to convert the DC power into the AC power;
A current detector provided on the AC motor output side of the power converter;
A ground fault detection means for comparing a current value detected by the current detector with a reference value, and detecting a ground fault of the AC motor side wiring of the power converter based on the comparison result;
Failure detection means for detecting a failure of the semiconductor element constituting the power conversion device;
A current breaker provided between the pantograph and the power converter;
When the ground fault detection by the ground fault detection means and the failure detection by the failure detection means occur at the same time, a shut-off means for shutting off the overhead wire and the power converter by the breaker,
An electric vehicle control device comprising: In the electric vehicle control device that converts the DC power supplied from the overhead line through the pantograph into AC power and drives the AC motor,
A power conversion device that includes a plurality of semiconductor elements as components and controls the plurality of semiconductor elements to convert the DC power into the AC power;
A current detector provided on the DC input side of the power converter;
A ground fault detection means for comparing the current value detected by the current detector with a reference value, and detecting a ground fault of the AC motor side wiring of the power converter, based on the comparison result;
A failure detection means for detecting a failure of the semiconductor element constituting the power converter;
A current breaker provided between the pantograph and the power converter;
When the ground fault detection by the ground fault detection means and the failure detection by the failure detection means occur at the same time, a shut-off means for shutting off the overhead wire and the power converter by the breaker,
An electric vehicle control device comprising:   3. The electric vehicle control device according to claim 1, further comprising means for arbitrarily setting a reference value of the ground fault detection means.   After the overhead wire and the power converter are shut off by the shut-off means, and the operation of the semiconductor element constituting the power converter is stopped, the shut-off state by the shut-off means input from the cab of the electric vehicle 3. The electric vehicle control device according to claim 1, further comprising means for invalidating a reset command for canceling the motor. The electric vehicle control device has a plurality of power conversion devices,
The current detector, the failure detection means and the breaker are provided for each power converter,
The ground fault detection means compares the current value detected by each current detector with the reference value,
The electric vehicle according to claim 1 or 2, wherein the shut-off means shuts off the overhead wire and each power converter independently based on detection results of the ground fault detection means and the plurality of failure detection means. Control device. A power conversion device comprising: a converter device that converts AC power supplied from an overhead line through a pantograph into DC power; and an inverter device that is connected to a DC output side of the converter device and converts the DC power into AC power. An electric vehicle control device for driving an AC motor by the inverter device,
A first current detector provided on the AC motor output side of the inverter device;
A second current detector provided between the converter device and the inverter device;
A third current detector provided on the AC input side of the converter device;
A ground fault detection means for comparing each current value detected by the first to third current detectors with a reference value, and detecting a ground fault of the power converter based on the comparison result;
First failure detection means for detecting a failure of the inverter device;
Second failure detection means for detecting a failure of the converter device;
A current breaker provided between the pantograph and the converter device;
When ground fault detection by the ground fault detection means and failure detection by the first or second failure detection means occur at the same time, a shut-off means for shutting off the overhead wire and the power converter by the breaker,
An electric vehicle control device comprising: After the interruption means and the power converter are interrupted by the interruption means, and the operation of the inverter device and the converter apparatus is stopped, the reset command for canceling the interruption state by the interruption means input from the cab of the electric vehicle is invalidated And means to
The electric vehicle control device according to claim 6, further comprising: The ground fault detection means compares the current value detected by the first to third current detectors with the first to third reference values, respectively.
7. The electric vehicle control device according to claim 6, further comprising means for arbitrarily setting the first to third reference values. The electric vehicle control device has a plurality of power conversion devices each composed of a converter device and an inverter device,
The first to third current detectors, the first and second failure detection means, and the breaker are provided for each of the plurality of power conversion devices,
The ground fault detection means compares the current value detected by each current detector with a reference value,
The electric vehicle control device according to claim 6, wherein the shut-off means shuts off the overhead line and each power converter independently based on detection results of the ground fault detection means and the plurality of failure detection means. .   The electric vehicle control device according to claim 1, wherein the reference value is a protection current value for protecting the AC motor from an overcurrent.

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