JP2017050999A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply capable of determining a failure of an opening/closing element without providing a dedicated discharge circuit.SOLUTION: The power supply includes: a capacitor connected to a charging time output terminal of a charge/discharge circuit; a voltage detection part for detecting voltage of the charging time output terminal; a control part for controlling to open/close an opening/closing element interposed in an electric path between the charging time output terminal and a storage battery; and a determination part for determining a failure of the opening/closing element on the basis of voltage detected by the voltage detection part when the control part controls the opening/closing element from close to open and the charge/discharge circuit is operated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply apparatus including a charge / discharge circuit that performs a charging operation for charging a storage battery and a discharging operation for discharging the storage battery.

  In recent years, vehicles such as HEV (Hybrid Electric Vehicle) and EV (Electric Vehicle) are becoming widespread. Such a vehicle is equipped with a power supply device that includes a charging operation for charging the storage battery and a charging / discharging circuit that performs a discharging operation for discharging the storage battery to supply power to the load. In such a power supply device, a relay is interposed in the electric path between the storage battery and the charge / discharge circuit so that the storage battery and the charge / discharge circuit can be shut off. In addition, a capacitor for suppressing voltage fluctuation is provided at the charging output terminal of the charge / discharge circuit in parallel with the storage battery.

  Further, when an electric circuit through which a large current flows is interrupted by a relay, the contact may be welded by arc discharge when the relay is turned on / off. For this reason, the relay is periodically turned on and off to determine the failure of the relay. The determination of failure is, for example, that after the relay is turned off (interruption of the electric circuit), the voltage of the output terminal at the time of charging of the charge / discharge circuit decreases, so that the relay has not failed (can be normally disconnected). Can be determined. However, even if the circuit between the storage battery and the charging / discharging circuit is cut off, if the capacity of the capacitor is large, it takes a relatively long time until the voltage at the output terminal during charging drops due to the spontaneous discharge of the capacitor. The failure of the relay cannot be determined in time.

  In view of this, a device provided with a dedicated discharge circuit is disclosed in order to quickly discharge the electric charge stored in the capacitor provided in the power supply device for suppressing voltage fluctuation (see Patent Documents 1 to 5). .

JP 2013-31259 A JP 2013-38903 A JP 2013-38895 A JP2013-132129A JP 2010-252475 A

  However, when a dedicated discharge circuit is provided, the size of the device may increase due to an increase in the number of parts, or the cost may increase. A failure of the relay (switching element) can be prevented for a short time without providing a dedicated discharge circuit. It is desirable that it can be determined.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a power supply device capable of determining a failure of an opening / closing element without providing a dedicated discharge circuit.

  A power supply device according to the present invention includes a charge / discharge circuit that performs a charging operation for charging a storage battery and a discharging operation for discharging, and a capacitor connected to an output terminal during charging of the charge / discharge circuit, and the output during charging. A voltage detection unit that detects a voltage of the terminal; a control unit that controls opening and closing of an open / close element interposed in an electric circuit between the output terminal during charging and the storage battery; and the control unit closes the open / close element And a determination unit that determines a failure of the switching element based on a voltage detected by the voltage detection unit when the charging and discharging circuit is operated.

  In the present invention, a capacitor is connected to the output terminal during charging of the charge / discharge circuit. In addition, an open / close element (for example, a relay) is interposed in the electric path between the output terminal during charging and the storage battery. That is, the storage battery and the capacitor are connected in parallel via the switching element. A voltage detection part detects the voltage of the output terminal at the time of charge. The control unit controls opening / closing of the opening / closing element. When the control unit controls the switching element from closed to open and operates the charge / discharge circuit, the determination unit determines a failure of the switching element based on the voltage detected by the voltage detection unit.

  For example, when the switching element is opened and the charging / discharging circuit is discharged, if the switching element is normal, the electric circuit between the storage battery and the capacitor is cut off (opened), so the voltage of the capacitor is short. Decrease during. However, when the switching element is faulty (short circuit), the electric circuit between the storage battery and the capacitor remains connected, so the voltage of the storage battery does not drop in a short time even when the discharge operation is started. The capacitor voltage does not change much.

  For example, when the charge / discharge circuit is charged by opening the switch element, if the switch element is normal, the electric circuit between the storage battery and the capacitor is cut off (open), so the capacitor voltage is short. Rise during. However, if the switching element is faulty (short-circuited), the electric circuit between the storage battery and the capacitor remains connected, so the voltage of the storage battery does not rise in a short time even when the charging operation is started. The capacitor voltage does not change much.

  As described above, when the control unit controls the opening / closing element from closed to open, when the charge / discharge circuit is operated, the voltage of the capacitor is detected without detecting the voltage of the capacitor. A failure can be determined.

  In the power supply device according to the present invention, the determination unit determines a failure of the switching element based on a voltage detected by the voltage detection unit after a predetermined time has elapsed since the charge / discharge circuit was operated.

  In the present invention, the determination unit determines the failure of the switching element based on the voltage detected by the voltage detection unit after a predetermined time has elapsed since the charge / discharge circuit was operated. The predetermined time can be, for example, 300 ms, but is not limited thereto. For example, when the charging / discharging circuit is discharged, the charging / discharging circuit becomes a discharging circuit that discharges the charge accumulated in the capacitor in a short time. Can be determined.

  In the power supply device according to the present invention, the determination unit includes a voltage detected by the voltage detection unit before operating the charge / discharge circuit, and a voltage detected by the voltage detection unit after operating the charge / discharge circuit. When the absolute value of the voltage difference is within a predetermined voltage threshold, the switch element is determined to be faulty.

  In the present invention, the determination unit is the absolute value of the voltage difference between the voltage detected by the voltage detection unit before operating the charge / discharge circuit and the voltage detected by the voltage detection unit after operating the charge / discharge circuit. Is within a predetermined voltage threshold, it is determined that the switching element is faulty.

  For example, when the switching element is opened and the charging / discharging circuit is discharged, if the switching element is faulty (short-circuited), the electric circuit between the storage battery and the capacitor remains connected. Even if it starts, the voltage of the storage battery does not drop in a short time, so the voltage difference between the capacitors before and after the charge / discharge circuit is operated is small. That is, when the absolute value of the voltage difference between the capacitors before and after the charge / discharge circuit is discharged is within a predetermined voltage threshold, it is possible to determine that the switching element is faulty.

  In addition, when the charge / discharge circuit is charged with the switch element open, if the switch element is faulty (short circuit), the electric circuit between the storage battery and the capacitor remains connected. Since the voltage of the storage battery does not rise in a short time even if it is started, the voltage difference between the capacitors before and after the charge / discharge circuit is operated is small. That is, when the absolute value of the voltage difference between the capacitors before and after the charging / discharging circuit is charged is within a predetermined voltage threshold, it is possible to determine that the switching element is faulty.

  In the power supply device according to the present invention, the determination unit detects the voltage detected by the voltage detection unit after operating the charging / discharging circuit and the voltage detection unit before performing the charging operation of the charging / discharging circuit. If the voltage difference from the voltage is within the voltage threshold, the switch element is determined to be faulty.

  In the present invention, the determination unit has a voltage difference between the voltage detected by the voltage detection unit after the charge / discharge circuit is charged and the voltage detected by the voltage detection unit before the charge / discharge circuit is charged. If it is within the voltage threshold, the switch element is determined to be faulty. When the switching element is faulty (short-circuited), the electric circuit between the storage battery and the capacitor remains connected, so the voltage of the storage battery does not rise in a short time even when the charging operation is started. That is, when the voltage difference between the voltage detected by the voltage detection unit after the charging operation and the voltage detected by the voltage detection unit before the charging operation is within the voltage threshold value, the switching element can be determined as a failure. .

  In the power supply device according to the present invention, the determination unit detects the voltage detected by the voltage detection unit before discharging the charge / discharge circuit, and the voltage detection unit after discharging the charge / discharge circuit. If the voltage difference from the voltage is within the voltage threshold, the switch element is determined to be faulty.

  In the present invention, the determination unit has a voltage difference between the voltage detected by the voltage detection unit before the charge / discharge circuit is discharged and the voltage detected by the voltage detection unit after the charge / discharge circuit is discharged. If it is within the voltage threshold, the switch element is determined to be faulty. When the switching element is faulty (short-circuited), the electric circuit between the storage battery and the capacitor remains connected, so that the voltage of the storage battery does not drop in a short time even when the discharge operation is started. That is, when the voltage difference between the voltage detected by the voltage detection unit before the discharge operation and the voltage detected by the voltage detection unit after the discharge operation is within the voltage threshold value, the switching element can be determined as a failure. .

  According to the present invention, it is possible to determine a failure of a switching element without providing a dedicated discharge circuit.

It is a block diagram which shows an example of a structure of a vehicle-mounted apparatus provided with the power supply device of this Embodiment. It is explanatory drawing which shows an example of the discharge operation of the power supply device of this Embodiment. It is explanatory drawing which shows an example of the charging operation of the power supply device of this Embodiment. It is explanatory drawing which shows an example of the failure determination of the relay by the power supply device of this Embodiment. It is a flowchart which shows an example of the procedure of the failure determination process of the power supply device of this Embodiment.

  Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof. FIG. 1 is a block diagram illustrating an example of a configuration of an in-vehicle device including the power supply device according to the present embodiment. As shown in FIG. 1, the in-vehicle device includes a DC / DC converter 50 as a power supply device, a relay 70 as an opening / closing element, a storage battery 81, a battery 82, a generator 83, a load 84, and the like. The DC / DC converter 50 includes a control unit 10, voltage detection units 21 and 22, a charge / discharge circuit 30, a capacitor 60, and the like, and discharges the storage battery 81 to charge the storage battery 81 and supply power to the load 84. The discharge operation is performed.

  The DC / DC converter 50 includes a control terminal 1 that controls the opening and closing of the contact 71 of the relay 70, an output terminal 2 that outputs a required voltage during a charging operation, and an output terminal 3 that outputs a required voltage during a discharging operation. A ground terminal 4 is provided. The capacitor 60 is connected between the output terminal 2 and the ground terminal 4 during charging.

  A relay 70 is interposed in the electric path between the charging output terminal 2 and the storage battery 81. That is, the storage battery 81 and the capacitor 60 are connected in parallel via the relay 70. The storage battery 81 is a secondary battery such as a lithium ion battery, for example. In addition, a battery 82, a generator 83, and a load 84 are connected to the discharge output terminal 3. Further, the control unit 10 controls the opening / closing of the contact 71 of the relay 70.

  The generator 83 generates electric power in conjunction with an engine (not shown), or generates regenerative electric power in conjunction with a vehicle braking operation. The generator 83 includes a rectifier (not shown), rectifies the generated power into direct current, and outputs the rectified direct current to the load 84, the battery 82, and the charge / discharge circuit 30.

  The charging / discharging circuit 30 converts the DC voltage output from the generator 83 into a required voltage under the control of the control unit 10, and outputs the converted voltage from the charging output terminal 2 to charge the storage battery 81 (charging). Operation). Moreover, the charging / discharging circuit 30 converts the voltage of the storage battery 81 into a required voltage under the control of the control unit 10, and outputs the converted voltage from the output terminal 3 during discharging (discharge operation).

  The charge / discharge circuit 30 includes transistors 31, 32, 33, and 34, diodes 41, 42, 43, and 44, an inductor 35, and the like connected in antiparallel between the collector and emitter of each transistor. The transistors 31 to 34 may be FETs or the like.

  More specifically, the collector of the transistor 31 is connected to the output terminal 2 during charging, the emitter of the transistor 31 is connected to the collector of the transistor 32, and the emitter of the transistor 32 is connected to the ground level. The collector of the transistor 33 is connected to the output terminal 3 during discharge, the emitter of the transistor 33 is connected to the collector of the transistor 34, and the emitter of the transistor 34 is connected to the ground level. One end and the other end of the inductor 35 are connected to the connection point between the emitter of the transistor 31 and the collector of the transistor 32 and the connection point between the emitter of the transistor 33 and the collector of the transistor 34, respectively. In addition, the structure of the charging / discharging circuit 30 is not limited to what is shown in FIG. 1, The structure of another buck-boost circuit may be sufficient.

  The voltage detector 21 detects the voltage of the output terminal 2 during charging. The voltage of the capacitor 60 is represented as Vcon. Moreover, the voltage of the storage battery 81 is represented as Vcap. The voltage detection unit 21 detects the voltage Vcon of the capacitor 60. The voltage detection unit 21 outputs the detected voltage to the control unit 10.

  The voltage detector 22 detects the voltage at the output terminal 3 during discharge. The voltage at the output terminal 3 during discharge is represented as Vbat. The voltage detection unit 22 outputs the detected voltage to the control unit 10.

  The control unit 10 includes a determination unit 11. When the control unit 10 controls the contact point 71 of the relay 70 from closed to open, the determination unit 11 detects the failure of the relay 70 based on the voltage detected by the voltage detection unit 21 when the charge / discharge circuit 30 is operated. Determine. In the example of FIG. 1, the control unit 10 includes the determination unit 11. However, the configuration is not limited thereto, and the determination unit 11 may be configured separately from the control unit 10.

  When determining the failure of the relay 70, the control unit 10 causes the charging / discharging circuit 30 to perform a discharging operation or a charging operation. More specifically, the magnitude of the voltage Vcon detected by the voltage detection unit 21 and the voltage Vbat detected by the voltage detection unit 22 is determined. When Vcon ≦ Vbat, the control unit 10 controls the charge / discharge circuit 30. Discharge operation. When Vcon> Vbat, the control unit 10 causes the charge / discharge circuit 30 to perform a charging operation.

  For example, when the contact point 71 of the relay 70 is opened and the charging / discharging circuit 30 is discharged, if the relay 70 is normal, the electric circuit between the storage battery 81 and the capacitor 60 is cut off (open). The voltage Vcon of the capacitor 60 decreases in a short time. However, since the electric circuit between the storage battery 81 and the capacitor 60 remains connected when the relay 70 is out of order (short circuit), the voltage of the storage battery 81 remains within a short time even when the discharge operation is started. Since the voltage does not decrease, the voltage Vcon of the capacitor 60 does not change much.

  Further, when the charge / discharge circuit 30 is charged by opening the contact point 71 of the relay 70, if the relay 70 is normal, the electric circuit between the storage battery 81 and the capacitor 60 is cut off (open). The voltage Vcon of the capacitor 60 rises in a short time. However, since the electric circuit between the storage battery 81 and the capacitor 60 remains connected when the relay 70 is out of order (short circuit), the voltage of the storage battery 81 remains within a short time even when the charging operation is started. Since the voltage does not rise, the voltage Vcon of the capacitor 60 does not change much.

  As described above, when the control unit 10 controls the contact point 71 of the relay 70 from closed to open, the dedicated discharge circuit is detected by detecting the voltage Vcon of the capacitor 60 when the charge / discharge circuit 30 is operated. It is possible to determine the failure of the relay 70 without providing a relay.

  Further, the determination unit 11 determines the failure of the relay 70 based on the voltage detected by the voltage detection unit 21 after a predetermined time has elapsed from the time when the charge / discharge circuit 30 is operated. The predetermined time can be, for example, 300 ms, but is not limited thereto. For example, when the charging / discharging circuit 30 is discharged, the charging / discharging circuit 30 becomes a discharging circuit that discharges the electric charge accumulated in the capacitor 60 in a short time. Therefore, the failure of the relay 70 without providing a dedicated discharging circuit. Can be determined in a short time.

  FIG. 2 is an explanatory diagram showing an example of the discharge operation of the power supply device 50 of the present embodiment. In FIG. 2, only a main part of the power supply device 50 is illustrated for simplicity. When the charging / discharging circuit 30 is discharged, the control unit 10 sets the transistor 31 to ON, sets the transistors 32 and 33 to OFF, and switches the transistor 34 at a predetermined cycle (repeats ON / OFF). For example, the switching frequency can be any numerical value of 100 kHz to 200 kHz, but is not limited thereto.

  When the electric circuit between the storage battery 81 and the charge / discharge circuit 30 is interrupted, when the charge / discharge circuit 30 is discharged, as shown by the solid line in FIG. It is discharged to the ground level through the transistor 31, inductor 35, and transistor 34. As a result, the voltage Vcon of the capacitor 60 can be reduced in a short time (for example, 300 ms or less) by the discharging operation of the charging / discharging circuit 30 without providing a dedicated discharging circuit, and can be almost 0V.

  FIG. 3 is an explanatory diagram showing an example of the charging operation of the power supply device 50 of the present embodiment. In FIG. 3, only a main part of the power supply device 50 is illustrated for simplicity. When the charging / discharging circuit 30 is charged, the control unit 10 sets the transistor 33 to ON, sets the transistors 31 and 34 to OFF, and switches the transistor 32 at a predetermined cycle (repeats ON / OFF). For example, the switching frequency can be any numerical value of 100 kHz to 200 kHz, but is not limited thereto.

  When the electric circuit between the storage battery 81 and the charge / discharge circuit 30 is interrupted, the charge / discharge circuit 30 is charged. First, when the transistor 32 is turned on, current flows to the ground level through the transistor 33, the inductor 35, and the transistor 32 as shown by the broken line in FIG. Next, when the transistor 32 is turned off, current flows through the diode 44, the inductor 35, and the diode 41 by the energy accumulated in the inductor 35 as shown by the solid line in FIG. Thereby, the charging operation of the charging / discharging circuit 30 can increase the voltage Vcon of the capacitor 60 in a short time (for example, 300 ms or less), and can be set to a predetermined value (for example, an output voltage value during charging).

  FIG. 4 is an explanatory diagram illustrating an example of failure determination of the relay 70 by the power supply device 50 according to the present embodiment. As shown in FIG. 4, the failure determination of the relay 70 has different determination results depending on the operating state of the charge / discharge circuit 30 and the voltage Vcon of the capacitor 60. This will be specifically described below.

  First, the case where the charging / discharging circuit 30 is discharged will be described. When the relay 70 is opened and the charging / discharging circuit 30 is discharged, if the relay 70 is out of order (short circuit failure of the contact 71), the electric circuit between the storage battery 81 and the capacitor 60 remains connected. Therefore, even if the discharge operation is started, the voltage of the storage battery 81 does not drop in a short time, so the voltage difference of the capacitor 60 before and after the charge / discharge circuit 30 is operated is small.

  The determination unit 11 determines that the voltage difference between the voltage Vcon detected by the voltage detection unit 21 before the charge / discharge circuit 30 is discharged and the voltage Vcon detected by the voltage detection unit 21 after the charge / discharge circuit 30 is discharged. When the voltage threshold is exceeded, it is determined that the relay 70 is normal. For example, when the voltage Vcon detected by the voltage detection unit 21 after the charge / discharge circuit 30 is discharged, the electric circuit between the storage battery 81 and the capacitor 60 is considered to be cut off. 70 can be determined to be normal.

  On the other hand, the determination unit 11 has a voltage Vcon detected by the voltage detection unit 21 before the charge / discharge circuit 30 is discharged and a voltage Vcon detected by the voltage detection unit 21 after the charge / discharge circuit 30 is discharged. If the difference is within the voltage threshold, the relay 70 is determined to be faulty. When the relay 70 is faulty (short-circuit fault of the contact point 71), the electric circuit between the storage battery 81 and the capacitor 60 remains connected, so that the voltage of the storage battery 81 is short for a short time even when the discharge operation is started. The voltage Vcon of the capacitor 60 does not decrease in a short time. That is, if the voltage difference between the voltage Vcon detected by the voltage detection unit 21 before the discharge operation and the voltage Vcon detected by the voltage detection unit 21 after the discharge operation is within the voltage threshold, the relay 70 is determined to be faulty. can do.

  Next, a case where the charge / discharge circuit 30 is charged will be described. When the charge / discharge circuit 30 is charged by opening the relay 70, if the relay 70 is faulty (short circuit fault of the contact point 71), the electric circuit between the storage battery 81 and the capacitor 60 remains connected. Therefore, even if the charging operation is started, the voltage of the storage battery 81 does not rise in a short time, so the voltage difference of the capacitor 60 before and after the charge / discharge circuit 30 is operated is small.

  The determination unit 11 has a voltage difference between the voltage Vcon detected by the voltage detection unit 21 after the charge / discharge circuit 30 is charged and the voltage Vcon detected by the voltage detection unit 21 before the charge / discharge circuit 30 is charged. When the voltage threshold is exceeded, it is determined that the relay 70 is normal. For example, when the voltage Vcon detected by the voltage detector 21 rises after exceeding the voltage threshold after the charging / discharging circuit 30 is charged, it is considered that the electric circuit between the storage battery 81 and the capacitor 60 is cut off. The relay 70 can be determined to be normal.

  On the other hand, the determination unit 11 is a voltage between the voltage Vcon detected by the voltage detection unit 21 after the charge / discharge circuit 30 is charged and the voltage Vcon detected by the voltage detection unit 21 before the charge / discharge circuit 30 is charged. If the difference is within the voltage threshold, the relay 70 is determined to be faulty. When the relay 70 is faulty (short-circuit fault of the contact point 71), the electric circuit between the storage battery 81 and the capacitor 60 remains connected, so the voltage of the storage battery 81 is short for a short time even when the charging operation is started. The voltage Vcon of the capacitor 60 does not rise in a short time. That is, if the voltage difference between the voltage Vcon detected by the voltage detection unit 21 after the charging operation and the voltage Vcon detected by the voltage detection unit 21 before the charging operation is within the voltage threshold, the relay 70 is determined to be a failure. can do.

  Next, the operation of the power supply device 50 of the present embodiment will be described. FIG. 5 is a flowchart illustrating an example of a procedure of failure determination processing of the power supply device 50 according to the present embodiment. Hereinafter, for the sake of convenience, the processing subject will be described as the control unit 10. The control unit 10 turns off the relay 70 (S11), and detects the voltage Vcon and the voltage Vbat (S12).

  The control unit 10 determines whether or not Vcon ≦ Vbat (S13). If Vcon ≦ Vbat (YES in S13), the control unit 10 performs a discharging operation (S14) and performs a process of step S16 described later. When Vcon ≦ Vbat is not satisfied (NO in S13), the control unit 10 performs a charging operation (S15), and performs a process of step S16 described later.

  The control unit 10 determines whether or not a predetermined time (for example, 300 ms) has elapsed since the start of the operation (S16). If the predetermined time has not elapsed (NO in S16), the process of step S16 is continued. When the predetermined time has elapsed (YES in S16), the control unit 10 determines whether or not the absolute value of the voltage difference of Vcon ≦ the voltage threshold before and after the start of the operation such as the discharging operation or the charging operation (S17). ).

  When the absolute value of the voltage difference ≦ the voltage threshold (YES in S17), the control unit 10 determines that the relay has failed (S18) and ends the process. When the absolute value of the voltage difference is not equal to or less than the voltage threshold (NO in S17), the control unit 10 determines that the relay is normal (S19), and ends the process.

  As described above, according to the present embodiment, it is possible to determine the failure of the relay 70 in which the contact 71 is short-circuited within a short time (for example, about 300 ms). In addition, the capacitor 60 can be stored in the capacitor 60 without providing a dedicated discharge circuit (for example, in order to discharge within a short time with the discharge resistor, the rated power of the discharge resistor increases and the size of the discharge resistor also increases). The generated charge can be discharged in a short time. Further, since it is not necessary to add a dedicated discharge circuit, an increase in cost can be avoided.

  The embodiments and examples disclosed above should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above embodiments and examples but by the scope of claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of claims. .

DESCRIPTION OF SYMBOLS 1 Control terminal 2 Output terminal at the time of charging 3 Output terminal at the time of discharge 4 Grounding terminal 10 Control part 11 Judgment part 21, 22 Voltage detection part 30 Charge / discharge circuit 31, 32, 33, 34 Transistor 35 Inductor 41, 42, 43, 44 Diode 50 DC / DC converter 60 Capacitor 70 Relay (open / close element)
71 Contact 81 Storage Battery 82 Battery 83 Generator 84 Load

Claims (5)

In a power supply device comprising a charging / discharging circuit that performs a charging operation for charging a storage battery and a discharging operation for discharging the storage battery,
A capacitor connected to the charge output terminal of the charge / discharge circuit;
A voltage detector for detecting the voltage at the charging output terminal;
A control unit for controlling opening and closing of an opening / closing element interposed in an electric circuit between the output terminal at the time of charging and the storage battery;
A determination unit configured to determine a failure of the switching element based on a voltage detected by the voltage detection unit when the control unit controls the switching element from closed to open and operates the charge / discharge circuit; A power supply device characterized by that. The determination unit
The power supply device according to claim 1, wherein a failure of the switching element is determined based on a voltage detected by the voltage detection unit after a predetermined time has elapsed from the time when the charge / discharge circuit is operated. The determination unit
The absolute value of the voltage difference between the voltage detected by the voltage detector before operating the charge / discharge circuit and the voltage detected by the voltage detector after operating the charge / discharge circuit is within a predetermined voltage threshold. 3. The power supply device according to claim 1, wherein if there is, the power supply device determines that the switching element is faulty. The determination unit
When the voltage difference between the voltage detected by the voltage detector after the charge / discharge circuit is charged and the voltage detected by the voltage detector before the charge / discharge circuit is charged is within the voltage threshold The power supply device according to claim 3, wherein the switch element is determined to be faulty. The determination unit
When the voltage difference between the voltage detected by the voltage detector before the charge / discharge circuit is discharged and the voltage detected by the voltage detector after the charge / discharge circuit is discharged is within the voltage threshold. The power supply device according to claim 3 or 4, wherein the switch element is determined to be faulty.

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