JP2010041806A - Power supply for electric railcar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply for an electric railcar, which detects a short circuit failure of a backflow preventing element for preventing current from flowing backward from a filter capacitor to an overhead contact line. <P>SOLUTION: When power is turned on, an initial charging circuit 19 turns off a short circuit switch 7 and charges the filter capacitor 9 via a charging resistor 6. When the charging of the filter capacitor 9 is completed, the initial charging circuit 19 turns on the short circuit switch 7 and suppresses a rush current to the filter capacitor 9 when the power is turned on. When operation stops, a discharging circuit 20 discharges the filter capacitor 9 via the initial charging circuit 19. When operation stops, a current detecting sensor 5 disposed between the initial charging circuit 19 and the discharging circuit 20 detects a discharging current from the filter capacitor 9 via the initial charging circuit 19. If the discharging current detected by the current detecting sensor 5 exceeds a predetermined value when the operation stops, a failure detecting section 18 determines that the backflow preventing element 8 of the initial charging circuit 19 is short-circuited. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric vehicle power supply device that receives electric power from an overhead wire and supplies electric power to a load of the electric vehicle.

  In general, in an electric vehicle power supply device, electric power is received from an overhead line, and electric power such as lighting and an air conditioner is supplied to the electric vehicle. This electric vehicle power supply device acquires the presence or absence of an overhead wire voltage with a voltage detector, and starts operation when a voltage is applied. A main converter for supplying electric power to a traveling motor for traveling on the electric vehicle is also connected to the electric vehicle power supply device under the pantograph.

The main converter is composed of a VVVF inverter, converted to AC power by the VVVF inverter to drive the electric motor of the train, the electric vehicle power supply device is composed of an inverter unit, and converted to AC power by the inverter unit, and the in-car load of the train There is one configured to supply electric power to (see, for example, Patent Document 1). The inverter unit inputs DC power through a filter capacitor, converts it into AC power, and supplies power to the in-vehicle load.
JP-A-6-261403

  However, since the electric vehicle power supply device and the main converter are connected to the same pantograph in parallel in the same manner, if the pantograph is disconnected from the overhead line, a power failure occurs. When the time for the pantograph to be disconnected from the overhead wire is short, the electric vehicle power supply device can supply electric power to the load side using the electric charge accumulated in the filter capacitor, and can prevent the fluorescent lamp and the like from being turned off. .

  Therefore, in order to prevent the electric charge of the filter capacitor of the electric vehicle power supply device from flowing out from the pantograph to the main converter connected in parallel, in general, the input circuit of the electric vehicle power supply device has a backflow prevention element ( For example, a diode or a thyristor is provided.

  If this backflow prevention element is short-circuited and the short-circuit failure is left as it is, the breakage in the backflow prevention element proceeds and eventually becomes a dielectric breakdown in the backflow prevention element. When a dielectric breakdown occurs in the backflow prevention element, a ground fault occurs, and in the worst case, a substation trip may be caused, resulting in a serious power outage situation. As for this backflow prevention element, since it is confirmed whether or not the short circuit is guaranteed by periodic inspection, there is no particular problem in terms of safety, but it is desirable to be able to detect short circuit failure of the backflow prevention element positively. It is.

  An object of the present invention is to provide a power supply device for an electric vehicle that can detect a short-circuit failure of a backflow prevention element that prevents a current from flowing from a filter capacitor to an overhead line.

  An electric vehicle power supply device according to the present invention is connected in parallel to a series circuit of an inverter having a filter capacitor for converting a direct current input from an overhead wire via a pantograph and a contactor into a sinusoidal PWM alternating current, a short-circuit switch, and a backflow prevention element. When the power is turned on, the short-circuit switch is turned off and the filter capacitor is charged through the charge resistor. When the filter capacitor is fully charged, the short-circuit switch is turned on and the filter capacitor is turned on. An initial charging circuit for suppressing an inrush current to the battery, a discharging circuit for discharging the charge of the filter capacitor through the initial charging circuit during a stop operation, and the initial charging circuit and the discharging circuit. A current for detecting a discharge current from the filter capacitor through the initial charging circuit during a stop operation An output sensor, and a failure detection unit that determines a short-circuit failure of the backflow prevention element of the initial charging circuit when the discharge current detected by the current detection sensor during a stop operation exceeds a predetermined value. It is characterized by.

  According to the present invention, it is possible to detect a short-circuit failure of a backflow prevention element that prevents current from flowing from the filter capacitor to the overhead line side.

  FIG. 1 is a configuration diagram of an electric vehicle power supply device 13 according to the first embodiment of the present invention. A direct current is inputted from the overhead line 1 through the pantograph 2 and inputted to the electric vehicle power supply device 13 and the main converter 14. The main converter 14 drives an electric motor that drives a train.

  In the electric vehicle power supply device 13, the DC input is input to the initial charging circuit 19 through the contactor 3 and the input reactor 4 that are turned ON / OFF. The initial charging circuit 19 is formed by connecting a charging resistor 6 in parallel to a series circuit of the short-circuit switch 7 and the backflow prevention element 8. When the power is turned on, the short-circuit switch 7 is open, and the current from the overhead wire 1 is supplied to the filter capacitor 9 described later through the charging resistor 6. Thereby, the inrush current to the filter capacitor 9 is suppressed. After the filter capacitor 9 is charged, the short-circuit switch 7 of the initial charging circuit 19 is closed.

  The direct current that has passed through the initial charging circuit 19 is input to the inverter 10. The AC filter 11 shapes the output of the inverter 10 into a sine wave, and obtains a vehicle power supply via the transformer 12. That is, the transformer 12 insulates the output of the AC filter 11 from the DC circuit, converts it to an arbitrary voltage, and supplies power to the train load.

  In addition, a discharge circuit 20 is provided for discharging the electric charge of the filter capacitor 9 via the initial charging circuit 19 when the electric vehicle power supply device 13 is stopped. The discharge circuit 20 is formed by a series circuit of a discharge resistor 15 and a discharge contactor 16.

  A current detection sensor 5 is provided between the initial charging circuit 19 and the discharging circuit 20, and the current detection sensor 5 passes through the initial charging circuit 19 from the filter capacitor 9 when the electric vehicle power supply device 13 is stopped. The detected discharge current is detected, and the detected discharge current is input to the failure detection unit 18. The failure detection unit 18 is a short circuit failure of the backflow prevention element 8 of the initial charging circuit 19 when the discharge current detected by the current detection sensor 5 exceeds the predetermined value during the stop operation of the electric vehicle power supply device 13. Is determined. Further, the contactor 3, the short-circuit switch 7 of the initial charging circuit 19, and the discharge contactor 16 of the discharge circuit 20 are controlled to open and close according to commands from the control unit 11.

  FIG. 2 is a waveform diagram of the discharge current detected by the current detection sensor 5 when the backflow prevention element 8 of the initial charging circuit 19 is normal during the stop operation of the electric vehicle power supply device 13. When the electric vehicle power supply device 13 is stopped, the control unit 17 turns off the discharge contactor 16 of the discharge circuit 20 (the contact of the discharge contactor 16 is on). When the discharge contactor 16 is turned off, the contact of the discharge contactor 16 is turned on. Therefore, when the backflow prevention element 8 of the initial charging circuit 19 is normal, the charge of the filter capacitor 9 is charged with the charging resistor 6 of the initial charging circuit 19. It is discharged through the discharge resistor 15 and the discharge contactor 16 of the discharge circuit 20. The peak value I1 of the current i1 detected by the current detection sensor 5 at this time is a value obtained by dividing the voltage of the filter capacitor 9 by the total value of the charging resistor 6 and the discharging resistor 15.

  FIG. 3 is a waveform diagram of the discharge current detected by the current detection sensor 5 when the backflow prevention element 8 of the initial charging circuit 19 has a short circuit failure during the stop operation of the electric vehicle power supply device 13. When the electric vehicle power supply device 13 is stopped, the discharge contactor 16 is turned off and the contact of the discharge contactor 16 is turned on. When the backflow prevention element 8 of the initial charging circuit 19 has a short circuit failure, the charge of the filter capacitor 9 passes through the shorted back prevention element 8 and the shorting switch 7 of the initial charging circuit 19 and the discharge resistor 15 of the discharge circuit 20. It is discharged through the discharge contactor 16. The peak value I2 of the current i2 detected by the current detection sensor 5 at this time is a value obtained by dividing the voltage of the filter capacitor 9 by the value of the discharge resistor 15.

  Therefore, when the current detected by the current detection sensor 5 is larger than the peak value I1 when the backflow prevention element 8 of the initial charging circuit 19 is normal, a short circuit failure occurs in the backflow prevention element 8 of the initial charging circuit 19. Can be determined to have occurred. Therefore, the failure detection unit 18 monitors the peak value of the discharge current of the filter capacitor 9 detected by the current detection sensor 5 during the stop operation of the electric vehicle power supply device 13 and short-circuits the backflow prevention element 8 of the initial charging circuit 19. Determine if there is a failure.

  FIG. 4 is a flowchart showing an example of processing contents of the failure detection unit 18 in the first embodiment. The failure detection unit 18 determines whether or not the electric vehicle power supply device 13 is in a stop operation (S1). If the electric vehicle power supply device 13 is in a stop operation, it is determined whether or not there is an off command for the discharge contactor 16 of the discharge circuit 20. (S2). When there is an off command for the discharge contactor 16, whether the peak value of the discharge current of the filter capacitor 9 detected by the current detection sensor 5 exceeds a predetermined value (a value greater than the peak value I1 and smaller than the peak value I2). (S3), if it exceeds, a notification that the backflow prevention element 8 is in failure is output (S4). Thereby, it is possible to easily detect a short circuit failure of the backflow prevention element 8 during the stop operation of the electric vehicle power supply device 13.

  In the above description, the short circuit failure of the backflow prevention element 8 is detected during the stop operation of the electric vehicle power supply device 13, but the short circuit failure of the backflow prevention element 8 is detected during the normal operation of the electric vehicle power supply device 13. You may make it do.

  FIG. 5 is a waveform diagram of the discharge current detected by the current detection sensor 5 when the backflow prevention element 8 of the initial charging circuit 19 is normal and the overhead wire voltage is lowered during the normal operation of the electric vehicle power supply device 13. FIG. 6 is a waveform diagram of the discharge current detected by the current detection sensor 5 when the overhead wire voltage is lowered while the backflow prevention element 8 of the initial charging circuit 19 is short-circuited during normal operation of the electric vehicle power supply device 13. .

  When the voltage of the overhead line 1 decreases during the normal operation of the electric vehicle power supply device 13, the filter capacitor 9 is charged, so that the short time until the voltage of the overhead line 1 and the voltage of the filter capacitor 9 become the same is the input current. No longer flows. As shown in FIG. 5, assuming that the voltage of the overhead line 1 drops at time t1, when the backflow prevention element 8 of the initial charging circuit 19 is in a normal state, the backflow prevention element 8 causes the charge of the filter capacitor 9 to be There is no flow to the side. When the voltage of the overhead line 1 and the voltage of the filter capacitor 9 become the same, in order to make the supplied power constant, a larger current flows than usual when the overhead line voltage 1 is decreasing, and the voltage of the overhead line 1 at time t2 When is recovered, the input current returns to the normal value.

  On the other hand, when the backflow prevention element 8 of the initial charging circuit 19 is in a short-circuit fault state, as shown in FIG. 6, if the voltage of the overhead line 1 drops at the time t1, the voltage of the overhead line 1 and the voltage of the filter capacitor 9 In a short period until they become the same, the charge of the filter capacitor 9 flows toward the overhead line 1 side. That is, since the electric charge of the filter capacitor 9 is also discharged to the overhead wire 1 side, a current flows in the minus direction with respect to the input.

  Therefore, when the current detected by the current detection sensor 5 flows from the filter capacitor 9 toward the overhead wire 1 during the normal operation, it can be determined that a short circuit failure has occurred in the backflow prevention element 8 of the initial charging circuit 19. Therefore, the failure detection unit 18 monitors the direction of the discharge current of the filter capacitor 9 detected by the current detection sensor 5 during the stop operation of the electric vehicle power supply device 13, and short-circuit failure of the backflow prevention element 8 of the initial charging circuit 19. Judgment of the presence or absence of.

  FIG. 7 is a flowchart showing another example of processing contents of the failure detection unit 18 in the first embodiment. The failure detection unit 18 determines whether or not the voltage of the overhead line 1 has decreased during the normal operation of the electric vehicle power supply device 13 (S11). When it is determined that the voltage of the overhead line 1 has decreased, the current detection sensor 5 It is determined whether or not the direction of the detected current is on the overhead line 1 side (S12), and when the current direction is on the overhead line side 1, a notification that the backflow prevention element 8 is faulty is output (S13). Thereby, it is possible to easily detect a short circuit failure of the backflow prevention element 8 during the normal operation of the electric vehicle power supply device 13.

  According to the first embodiment, the current detection sensor 5 is installed between the initial charging circuit 19 and the discharge circuit 20, and the current detection sensor 5 is used when the electric vehicle power supply device 13 is stopped or operated normally. Since the short-circuit failure of the backflow prevention element 8 of the initial charging circuit 19 can be detected based on the magnitude or direction of the detected current, the short-circuit failure of the backflow prevention element can be reliably detected with a simple configuration.

  FIG. 8 is a configuration diagram of a power supply device for an electric vehicle according to the second embodiment of the present invention. This second embodiment is different from the first embodiment shown in FIG. 1 in that the current detection sensor 5 is replaced with an initial charge circuit 19 and a discharge circuit 20 instead of the current detection sensor 5. 5 is installed in the series circuit of the short-circuit switch 7 and the backflow prevention element 8 of the initial charging circuit 19, and the series circuit of the short-circuit switch 7 and the backflow prevention element 8 of the initial charging circuit 19 is stopped when the electric vehicle power supply device 13 is stopped. When the electric current detected by the current detection sensor 5 during the stop operation of the electric vehicle power supply device 13 exceeds a predetermined value, the failure determination unit 18 detects the flowing current. It is determined that it is a short circuit failure. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 8, the current detection sensor 5 is installed in a series circuit of the short-circuit switch 7 and the backflow prevention element 8 in the initial charging circuit 19. The current detection sensor 5 detects the current flowing in the series circuit of the short-circuit switch 7 and the backflow prevention element 8 of the initial charging circuit 19 during the stop operation of the electric vehicle power supply device 13 and outputs it to the failure detection unit 18.

  FIG. 9 is a waveform diagram of the discharge current detected by the current detection sensor 5 when the backflow prevention element 8 of the initial charging circuit 19 is normal during the stop operation of the electric vehicle power supply device 13, and FIG. 7 is a waveform diagram of the discharge current detected by the current detection sensor 5 when the backflow prevention element 8 of the initial charging circuit 19 has a short circuit failure during the stop operation of the power supply device 13 for electric power.

  During the stop operation of the electric vehicle power supply device 13, when the discharge contactor 16 of the discharge circuit 20 is turned off, the contact of the discharge contactor 16 is turned on. When the backflow prevention element 8 of the initial charging circuit 19 is normal, the charge of the filter capacitor 9 is discharged through the charging resistor 6 of the initial charging circuit 19, the discharging resistor 15 of the discharging circuit 20, and the discharging contactor 16. . Since the current detection sensor 5 is not arranged in this current path, when the backflow prevention element 8 of the initial charging circuit 19 is normal, the current detected by the current detection sensor 5 is zero as shown in FIG. is there.

  On the other hand, when the backflow prevention element 8 of the initial charging circuit 19 is short-circuited, the charge of the filter capacitor 9 passes through the backflow prevention element 8 and the shorting switch 7 of the initial charging circuit 19 and the discharge resistor 15 of the discharge circuit 20. It is discharged through the discharge contactor 16. Therefore, when the backflow prevention element 8 of the initial charging circuit 19 has a short circuit failure, the current detection sensor 5 detects the current detected by the current detection sensor 5 as the voltage of the filter capacitor 9 as shown in FIG. The current value I2 is a value obtained by dividing by the value of. Accordingly, when the current detected by the current detection sensor 5 of the second embodiment exceeds a predetermined value (a set value for detecting the presence of the current value I2) during the stop operation, the initial charging circuit 19 is used. It can be determined that the backflow prevention element 8 is a short circuit failure.

  FIG. 11 is a flowchart showing the processing contents of the failure detection unit 18 in the second embodiment. The failure detection unit 18 determines whether or not the electric vehicle power supply device 13 is in a stop operation (S21). If the electric vehicle power supply device 13 is in a stop operation, it is determined whether or not there is an off command for the discharge contactor 16 of the discharge circuit 20. (S22). When there is an off command for the discharge contactor 16, it is determined whether or not the peak value of the current detected by the current detection sensor 5 exceeds a predetermined value (a value greater than zero and less than the peak value I2) (S23). When it exceeds, the backflow prevention element 8 outputs a notification that it is a failure (S24). Thereby, it is possible to easily detect a short circuit failure of the backflow prevention element 8 during the stop operation of the electric vehicle power supply device 13.

  According to the second embodiment, the current detection sensor 5 is installed in a series circuit of the short-circuit switch 7 and the backflow prevention element 8 of the initial charging circuit 19, and the initial charging circuit 19 is stopped when the electric vehicle power supply device 13 is stopped. When the current flowing through the series circuit of the short-circuit switch 7 and the backflow prevention element 8 exceeds a predetermined value, it is determined that the backflow prevention element 8 of the initial charging circuit 19 is a short-circuit failure, so that it can be reliably achieved with a simple configuration. It is possible to detect a short circuit failure of the backflow prevention element.

  FIG. 12 is a block diagram of an electric vehicle power supply apparatus according to the third embodiment of the present invention. This third embodiment is different from the first embodiment shown in FIG. 1 in that the current detection sensor 5 is replaced with an initial charge circuit 19 and a discharge circuit 20 instead of the current detection sensor 5. 5 is installed in series with the charging resistor 6 of the initial charging circuit 19 to detect a current flowing through the charging resistor 6 of the initial charging circuit 19 when the electric vehicle power supply device 13 is stopped. When the current detected by the current detection sensor 5 during the stop operation 13 is less than a predetermined value, it is determined that a short circuit failure has occurred in the backflow prevention element 8 of the initial charging circuit 19. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 12, the current detection sensor 5 is installed in series with the charging resistor 6 in the initial charging circuit 19. The current detection sensor 5 detects the current flowing through the charging resistor 6 of the initial charging circuit 19 during the stop operation of the electric vehicle power supply device 13 and outputs it to the failure detection unit 18.

  FIG. 13 is a waveform diagram of the discharge current detected by the current detection sensor 5 when the backflow prevention element 8 of the initial charging circuit 19 is normal during the stop operation of the electric vehicle power supply device 13, and FIG. 7 is a waveform diagram of the discharge current detected by the current detection sensor 5 when the backflow prevention element 8 of the initial charging circuit 19 has a short circuit failure during the stop operation of the power supply device 13 for electric power.

  During the stop operation of the electric vehicle power supply device 13, when the discharge contactor 16 of the discharge circuit 20 is turned off, the contact of the discharge contactor 16 is turned on. When the backflow prevention element 8 of the initial charging circuit 19 is normal, the charge of the filter capacitor 9 is discharged through the charging resistor 6 of the initial charging circuit 19, the discharging resistor 15 of the discharging circuit 20, and the discharging contactor 16. . Since the current detection sensor 5 detects the current flowing through the charging resistor 6, when the backflow prevention element 8 of the initial charging circuit 19 is normal, the current detected by the current detection sensor 5 is a filter as shown in FIG. The current value I1 is a value obtained by dividing the voltage of the capacitor 9 by the total value of the charging resistor 6 and the discharging resistor 15.

  On the other hand, when the backflow prevention element 8 of the initial charging circuit 19 is short-circuited, the charge of the filter capacitor 9 passes through the backflow prevention element 8 and the shorting switch 7 of the initial charging circuit 19 and the discharge resistor 15 of the discharge circuit 20. It is discharged through the discharge contactor 16. Since the current detection sensor 5 is not arranged in this current path, the current detected by the current detection sensor 5 is zero. Therefore, when the current detected by the current detection sensor 5 of the third embodiment is less than a predetermined value (a value smaller than the current value I1) during the stop operation, it is a short circuit failure of the backflow prevention element 8 of the initial charging circuit 19. Can be determined.

  FIG. 15 is a flowchart showing the processing contents of the failure detection unit 18 in the third embodiment. The failure detection unit 18 determines whether or not the electric vehicle power supply device 13 is in a stop operation (S31). If the electric vehicle power supply device 13 is in a stop operation, it is determined whether or not there is an off command for the discharge contactor 16 of the discharge circuit 20. (S32). When there is an off command of the discharge contactor 16, it is determined whether or not the current detected by the current detection sensor 5 is less than a predetermined value (a value smaller than the current value I1) (S33). The backflow prevention element 8 outputs a notification indicating that there is a failure (S34). Thereby, it is possible to easily detect a short circuit failure of the backflow prevention element 8 during the stop operation of the electric vehicle power supply device 13.

  According to the third embodiment, the current detection sensor 5 is installed in series with the charging resistor 6 of the initial charging circuit 19, and the current detected by the current detection sensor 5 during the stop operation of the electric vehicle power supply device 13 is a predetermined value. If it is less than this, it is a short circuit failure of the backflow prevention element 8 of the initial charging circuit 19, and therefore a short circuit failure of the backflow prevention element 8 can be reliably detected with a simple configuration.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram of the electric vehicle power supply device concerning the 1st Embodiment of this invention. The wave form diagram of the discharge current detected with the current detection sensor when the backflow prevention element of the initial stage charging circuit is normal at the time of the stop operation of the electric vehicle power supply device according to the first embodiment of the present invention. The wave form diagram of the discharge current detected with the current detection sensor when the backflow prevention element of the initial stage charging circuit is a short circuit failure at the time of the stop operation of the electric vehicle power supply device according to the first embodiment of the present invention The flowchart which shows an example of the processing content of the failure detection part 18 in the 1st Embodiment of this invention. The waveform of the discharge current detected by the current detection sensor when the backflow prevention element of the initial charging circuit is normal and the overhead line voltage is reduced during the normal operation of the electric vehicle power supply apparatus according to the first embodiment of the present invention Figure. The discharge detected by the current detection sensor when the overhead line voltage is lowered in a state where the backflow prevention element of the initial charging circuit is short-circuited during normal operation of the electric vehicle power supply apparatus according to the first embodiment of the present invention. Waveform diagram of current. The flowchart which shows another example of the processing content of the failure detection part in the 1st Embodiment of this invention. The block diagram of the electric vehicle power supply device concerning the 2nd Embodiment of this invention. The wave form diagram of the discharge current detected with the electric current detection sensor when the backflow prevention element of the initial stage charging circuit is normal at the time of the stop operation | movement of the electric vehicle power supply device concerning the 2nd Embodiment of this invention. The wave form diagram of the discharge current detected with the electric current detection sensor when the backflow prevention element of the initial stage charging circuit at the time of the stop operation | movement of the electric vehicle power supply device concerning the 2nd Embodiment of this invention has failed. The flowchart which shows the processing content of the failure detection part 18 in the 2nd Embodiment of this invention. The block diagram of the power supply device for electric vehicles concerning the 3rd Embodiment of this invention. The wave form diagram of the discharge current detected with the current detection sensor when the backflow prevention element of the initial stage charging circuit is normal at the time of the stop operation | movement of the electric vehicle power supply device concerning the 3rd Embodiment of this invention. The wave form diagram of the discharge current detected with the electric current detection sensor when the backflow prevention element of the initial stage charging circuit at the time of the stop operation | movement of the electric vehicle power supply device concerning the 3rd Embodiment of this invention has failed. The flowchart which shows the processing content of the failure detection part in the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Overhead wire, 2 ... Pantograph, 3 ... Contactor, 4 ... Input reactor, 5 ... Current detection sensor, 6 ... Charging resistance, 7 ... Short-circuit switch, 8 ... Backflow prevention element, 9 ... Filter capacitor, 10 ... Inverter, 11 DESCRIPTION OF SYMBOLS ... AC filter, 12 ... Transformer, 13 ... Electric vehicle power supply device, 14 ... Main converter, 15 ... Discharge resistor, 16 ... Discharge contactor, 17 ... Control part, 18 ... Fault detection part, 19 ... Initial charging circuit 20 ... Discharge circuit

Claims (4)

It is formed by connecting a charging resistor in parallel to a series circuit of a short-circuit switch and a backflow prevention element, and an inverter having a filter capacitor that converts a direct current input from an overhead line via a pantograph and a contactor into a sinusoidal PWM alternating current. Sometimes the short-circuit switch is turned off, the filter capacitor is charged via a charging resistor, and when the filter capacitor is fully charged, the short-circuit switch is turned on and initial charging for suppressing the inrush current to the filter capacitor when the power is turned on. A circuit, a discharge circuit that discharges the charge of the filter capacitor via the initial charge circuit during a stop operation, and the initial charge from the filter capacitor that is installed between the initial charge circuit and the discharge circuit during the stop operation A current detection sensor for detecting a discharge current through the circuit, and the current during stop operation An electric vehicle power supply device comprising: a failure detection unit that determines that a short circuit failure has occurred in the backflow prevention element of the initial charging circuit when the discharge current detected by the output sensor exceeds a predetermined value . When the current detected by the current detection sensor during normal operation is flowing from the filter capacitor toward the overhead wire side, the failure detection unit is a short circuit failure of the backflow prevention element of the initial charging circuit. The electric vehicle power supply device according to claim 1, wherein the determination is made. It is formed by connecting a charging resistor in parallel to a series circuit of a short-circuit switch and a backflow prevention element, and an inverter having a filter capacitor that converts a direct current input from an overhead line via a pantograph and a contactor into a sinusoidal PWM alternating current. Sometimes the short-circuit switch is turned off, the filter capacitor is charged via a charging resistor, and when the filter capacitor is fully charged, the short-circuit switch is turned on and initial charging for suppressing the inrush current to the filter capacitor when the power is turned on. An initial charging circuit installed in a series circuit of a circuit, a discharging circuit for discharging the charge of the filter capacitor through the initial charging circuit during a stop operation, and a short circuit switch and a backflow prevention element of the initial charging circuit Current detection sensor that detects the current flowing in the series circuit of the short-circuit switch and the backflow prevention element And a failure detection unit that determines that a short-circuit failure has occurred in the backflow prevention element of the initial charging circuit when the discharge current detected by the current detection sensor during a stop operation exceeds a predetermined value. An electric vehicle power supply device. It is formed by connecting a charging resistor in parallel to a series circuit of a short-circuit switch and a backflow prevention element, and an inverter having a filter capacitor that converts a direct current input from an overhead line via a pantograph and a contactor into a sinusoidal PWM alternating current. Sometimes the short-circuit switch is turned off, the filter capacitor is charged via a charging resistor, and when the filter capacitor is fully charged, the short-circuit switch is turned on and initial charging for suppressing the inrush current to the filter capacitor when the power is turned on. A circuit, a discharging circuit for discharging the charge of the filter capacitor through the initial charging circuit during the stop operation, and a current that flows in the charging resistor of the initial charging circuit during the stop operation that is installed in series with the charging resistor of the initial charging circuit A current detection sensor for detecting current and a discharge detected by the current detection sensor during a stop operation Flow electric vehicle power supply device being characterized in that a and determining fault detection unit when less than the predetermined value is a short circuit fault back current prevention elements of said initial charging circuit.

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