JP2019009934A - Charging/discharging device - Google Patents

Abstract

To achieve pre-charging of a smoothing capacitor at the start of power supply from the direct current power supply to the load and discharging of the smoothing capacitor at the stop of power supply in a compact configuration.SOLUTION: When accumulated charge of a smoothing capacitor C is discharged, the smoothing capacitor C is disconnected from a DC power supply V by turning off a first to third switches SW1 to SW3, by turning on a fourth switch SW4 of a discharge line 5, a resistor R1, the fourth switch SW4, a discharging circuit by a negative electrode line N on the side of the smoothing capacitor C rather than a second switch SW2 are connected between both poles of the smoothing capacitor C to discharge the accumulated charge of the smoothing capacitor C. At the time of pre-charging the smoothing capacitor C, the DC power supply V is separated by turning off the first to third switches SW1 to SW3, and the smoothing capacitor C disconnected from the discharging circuit by turning off the fourth switch SW4 is connected to the DC power supply V via the resistor R1 of a pre-charge line 3 by turning on the second and third switches SW2 and SW3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a smoothing capacitor charging / discharging device that smoothes power from a DC power supply to a load.

  When the supply of the power smoothed by the smoothing capacitor to the load from the DC power supply is stopped, the switch is turned on, and a discharge circuit having a discharge resistor is connected to the smoothing capacitor. A discharge control device that discharges residual charges is known (for example, Patent Document 1).

Japanese Patent Laid-Open No. 2006-86578

  By the way, the above-described smoothing capacitor is connected to the DC power supply via a precharge resistor when starting the power supply from the DC power supply to the load. By using the precharge resistor, the inrush current can be prevented from flowing to the smoothing capacitor at the start of power supply, and the smoothing capacitor can be gradually charged.

  Instead, two resistors for precharging and discharging are required for charging and discharging the smoothing capacitor. Moreover, it is necessary to use resistance elements having higher performance than originally required for these resistors in order to provide a margin for resistance against large currents and heat dissipation performance. Therefore, a configuration that requires two resistors for precharging and discharging is likely to increase the size of the device.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to precharge the smoothing capacitor when starting the power supply from the DC power source to the load and the residual charge of the smoothing capacitor when stopping the power supply. Is to be able to be realized with a compact configuration.

In order to achieve the above object, a charge / discharge device according to one aspect of the present invention comprises:
Smoothing the power supplied from the DC power supply and outputting it to the load, and a smoothing capacitor that discharges when the power supply from the DC power supply stops,
A shut-off module capable of shutting off power supply from the DC power source to the smoothing capacitor;
A resistor element connected in parallel with the cutoff module between the DC power source and the smoothing capacitor, and a current flowing at the time of precharging and discharging of the smoothing capacitor;
An open module that includes the smoothing capacitor and the resistance element, and that is provided closer to the smoothing capacitor than the shut-off module and that can open a discharge circuit through which the current during discharge flows.
Is provided.

  According to the present invention, the smoothing capacitor precharge when the power supply from the DC power supply to the load is started and the discharge of the residual charge of the smoothing capacitor when the power supply is stopped are realized with a compact configuration. Can do.

It is explanatory drawing which shows the structure of the circuit part of the charging / discharging apparatus which concerns on 1st Embodiment of this invention. It is a block diagram which shows schematic structure of the control system of the electric vehicle containing the control part of the charging / discharging apparatus of FIG. It is a flowchart which shows the procedure of the control which the motor controller of FIG. 1 performs at the time of the precharge of a smoothing capacitor. FIG. 4 is an explanatory diagram showing an open / close state of each switch when the smoothing capacitor of FIG. 1 is precharged by the procedure of FIG. 3. It is explanatory drawing which shows the open / close state of each switch after the precharge of the smoothing capacitor of FIG. 1 by the procedure of FIG. It is a flowchart which shows the procedure of the control which the motor controller of FIG. 1 performs at the time of discharge of a smoothing capacitor. It is explanatory drawing which shows the opening / closing state of each switch at the time of discharging the smoothing capacitor of FIG. 1 in the procedure of FIG. It is explanatory drawing which shows the case where the discharge switch of the charging / discharging apparatus of FIG. 1 made into the open / close state of FIG. 2 is a flowchart showing a control procedure including determination of ON fixation of a discharge switch performed by the motor controller of FIG. 1 when a smoothing capacitor is precharged. It is explanatory drawing which shows the state of the circuit part of a charging / discharging apparatus in case the discharge switch is not on-fixed at the time of the on-fixation determination of FIG. It is explanatory drawing which shows the state of the circuit part of a charging / discharging apparatus in case the discharge switch is fixed on at the time of the on fixation determination of FIG. It is explanatory drawing which shows the structure of the circuit part of the charging / discharging apparatus which concerns on 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a configuration of a circuit portion of a power control device for an electric vehicle according to a first embodiment of the present invention to which the charge / discharge device of the present invention is applied, and FIG. 2 is a control system of the power control device of FIG. It is a block diagram which shows schematic structure.

  The power control apparatus of this embodiment is mounted on an electric vehicle such as an electric vehicle (EV) or a hybrid vehicle (HEV).

  As shown in FIG. 1, this power control device has a charging / discharging device 1 for a smoothing capacitor C connected between a positive electrode line P and a negative electrode line N that supply power from a DC power source V to an inverter INV. . The smoothing capacitor C discharges the electric charge accumulated while smoothing the power of the DC power supply V and outputting it to the inverter INV after stopping the output of the smoothing power to the inverter INV.

  The charging / discharging device 1 includes a positive electrode line P and a negative electrode line N, a precharge line 3, a discharge line 5, first to fourth switches SW1 to SW4, a resistor R1, a voltage sensor 7, and a motor controller 9. .

  The positive electrode line P and the negative electrode line N are paths for supplying the power of the DC power source V to the inverter INV, and both electrodes of the smoothing capacitor C are connected to the positive electrode line P and the negative electrode line N, respectively.

  The first switch SW1 and the second switch SW2 (corresponding to the cutoff module in the claims) are provided between the DC power source V and the smoothing capacitor C of the positive line P and the negative line N. The first switch SW1 and the second switch SW2 can be turned off to cut off the power supply from the DC power source V to the inverter INV.

  The third switch SW3 (corresponding to the precharge switch in the claims) is provided on the precharge line 3 of the smoothing capacitor C. The precharge line 3 connects the positive electrode of the DC power source V and the positive electrode of the smoothing capacitor C in parallel with the portion between the DC power source V and the smoothing capacitor C of the positive electrode line P provided with the first switch SW1. ing.

  A fourth switch SW4 (corresponding to an open module and a discharge switch in the claims) is provided in the discharge line 5 that connects the precharge line 3 and the negative electrode line N in parallel with the smoothing capacitor C to the DC power source V. Yes.

  The discharge line 5 is connected to the positive electrode side of the smoothing capacitor C with respect to the third switch SW3 of the precharge line 3. Further, the discharge line 5 is connected to the negative electrode side of the smoothing capacitor C from the second switch SW2 of the negative electrode line N. Therefore, the fourth switch SW4 of the discharge line 5 is connected in series with the third switch SW3 of the precharge line 3 with respect to the DC power supply V.

  The resistor R1 (corresponding to the resistor element in the claims) is provided on the positive electrode side of the smoothing capacitor C with respect to the connection portion of the discharge line 5 of the precharge line 3. Therefore, the series circuit of the resistor R1 and the smoothing capacitor C is connected in parallel with the discharge line 5 with respect to the DC power supply V.

  The voltage sensor 7 is connected in parallel with the smoothing capacitor C between the positive electrode line P and the negative electrode line N. The voltage sensor 7 measures a potential difference between both electrodes of the smoothing capacitor C.

  The potential difference between both electrodes of the smoothing capacitor C measured by the voltage sensor 7 described above is input to the motor controller 9 shown in FIG. The motor controller 9 operates the inverter INV in a pattern that causes the electric motor M for propulsion to output torque corresponding to a torque command value input from an ECU (Electronic Control Unit or Engine Control Unit) of the electric vehicle.

  Further, the motor controller 9 controls the on / off of the first to fourth switches SW1 to SW4 during precharging or discharging of the smoothing capacitor C, thereby forming a precharging circuit or discharging circuit for the smoothing capacitor C. Note that the measured value of the voltage sensor 7 is referred to when the on-fixation diagnosis of the fourth switch SW4 is performed by the motor controller 9 when the discharge circuit is formed.

  The precharging of the smoothing capacitor C is executed under the control of the motor controller 9 when an ignition switch (not shown) of the electric vehicle is turned on. Hereinafter, the procedure of the precharge process of the smoothing capacitor C performed by the motor controller 9 when the ignition switch is turned on will be described with reference to the flowchart of FIG.

  First, when an ignition switch (not shown) is turned on, the motor controller 9 starts from the state where all of the first to fourth switches SW1 to SW4 are turned off, and then the third switch SW3 of the precharge line 3 and the second switch of the negative line N. SW2 is switched on (step S1).

  Thereby, as shown in FIG. 4, the precharge circuit that returns to the DC power supply V through the DC power supply V, the third switch SW3 of the precharge line 3, the resistor R1, the smoothing capacitor C, and the second switch SW2 of the negative electrode line N is provided. It is formed.

  Then, as shown in FIG. 3, the motor controller 9 confirms whether or not the voltage applied between both electrodes of the smoothing capacitor C measured by the voltage sensor 7 has sufficiently increased to precharge the smoothing capacitor C (step). S3).

  At this time, the potential of the negative electrode of the smoothing capacitor C is 0 V, which is the same as the negative electrode of the DC power supply V, because the second switch SW2 of the negative electrode line N is off. For this reason, a voltage of the potential of the positive electrode of the smoothing capacitor C is applied between both electrodes of the smoothing capacitor C.

  If the voltage applied across the smoothing capacitor C is not sufficiently increased and the smoothing capacitor C has not yet been precharged (NO in step S3), the motor controller 9 determines whether the third switch SW3 and the second switch SW2 The on state is maintained (step S5), and the precharge circuit is formed and maintained.

  On the other hand, when the voltage applied between both electrodes of the smoothing capacitor C is sufficiently increased and the smoothing capacitor C is precharged (NO in step S3), the motor controller 9 turns off the third switch SW3 of the precharge line 3. (Step S7), then, the first switch SW1 of the positive line P is turned on (Step S9), and the sequence of the precharge process is ended.

  Thereby, the charging / discharging apparatus 1 switches from the precharge state of the smoothing capacitor C to a normal power supply state. In a normal power supply state, as shown in FIG. 5, the power of the DC power source V is smoothed by the smoothing capacitor C through the first switch SW1 of the positive line P and the second switch SW2 of the negative line N, and then the inverter. Output to INV.

  Further, the discharge of the electric charge accumulated in the smoothing capacitor C while the power of the DC power supply V is supplied to the inverter INV is executed under the control of the motor controller 9 when an ignition switch (not shown) is turned off. Hereinafter, the procedure of the discharge process of the smoothing capacitor C performed by the motor controller 9 when the ignition switch is turned off will be described with reference to the flowchart of FIG.

  First, when an ignition switch (not shown) is turned off, the motor controller 9 switches on the fourth switch SW4 of the discharge line 5 from the state where all of the first to fourth switches SW1 to SW4 are turned off (step S11) ( Step S13).

  As a result, as shown in FIG. 7, a discharge circuit is formed that returns to the negative electrode of the smoothing capacitor C via the positive electrode of the smoothing capacitor C, the resistor R1 of the precharge line 3, the fourth switch SW4 of the discharge line 5, and the negative electrode line N. The

  Then, as shown in FIG. 6, the motor controller 9 confirms whether or not the potential difference between both electrodes of the smoothing capacitor C measured by the voltage sensor 7 has sufficiently decreased and the smoothing capacitor C has sufficiently discharged the accumulated charge ( Step S15).

  When the potential difference between the two electrodes of the smoothing capacitor C is not sufficiently lowered and the smoothing capacitor C has not been sufficiently discharged (NO in step S15), the motor controller 9 maintains the ON state of the fourth switch SW4. (Step S17), the discharge circuit is kept formed.

  On the other hand, when the potential difference between both electrodes of the smoothing capacitor C is sufficiently lowered and the smoothing capacitor C is sufficiently discharged (NO in step S15), the motor controller 9 turns off the fourth switch SW4 of the discharge line 5 ( Step S19), the sequence of the discharge process is terminated.

  As described above, according to the charging / discharging device 1 of the present embodiment, the smoothing capacitor C that smoothes the power supplied from the DC power source V to the inverter INV accumulates when the power supply from the DC power source V to the inverter INV is stopped. When discharging the electric charge, the smoothing capacitor C is disconnected from the DC power source V by turning off the first to third switches SW1 to SW3.

  Then, when the fourth switch SW4 of the discharge line 5 existing on the smoothing capacitor C side from the first to third switches SW1 to SW3 is turned on, the resistor R1, the fourth switch SW4, and the second switch SW2 are on the smoothing capacitor C side. The discharge circuit using the negative electrode line N is used to connect both electrodes of the smoothing capacitor C to discharge the accumulated charge of the smoothing capacitor C.

  Further, when the smoothing capacitor C is precharged, the smoothing capacitor is disconnected from the DC power source V by turning off the first to third switches SW1 to SW3 and also disconnected from the discharge circuit by turning off the fourth switch SW4. C is connected to the DC power source V via the resistor R1 of the precharge line 3 when the second and third switches SW2 and SW3 are turned on.

  Therefore, one resistor R1 serves as both a precharging resistor and a discharging resistor of the smoothing capacitor C. Therefore, even if a high-performance resistance element is used for the pre-charging resistor or discharging resistor of the smoothing capacitor C in order to satisfy the resistance against large current and the heat radiation performance, the single resistor R1 serves both purposes. Thus, the apparatus can be miniaturized with a minimum configuration.

  By the way, when the third switch SW3 and the second switch SW2 are switched on to precharge the smoothing capacitor C, if the fourth switch SW4 of the discharge line 5 is fixed on, as shown in FIG. In addition, the DC power supply V is short-circuited.

  Therefore, in the charging / discharging device 1 of the present embodiment, the motor controller 9 performs the on-fixation diagnosis of the fourth switch SW4 at the beginning of the precharge process of the smoothing capacitor C shown in FIG.

  Specifically, the motor controller 9 executes the process of each procedure of steps S01 to S07 shown in FIG. 9 instead of step S1 of the precharge process of FIG.

  That is, when an ignition switch (not shown) is turned on, the motor controller 9 switches on the third switch SW3 of the precharge line 3 from the state where all of the first to fourth switches SW1 to SW4 are off (step S01). .

  As a result, as shown in FIG. 10, the positive electrode of the DC power supply V is connected to the positive electrode of the smoothing capacitor C via the third switch SW3 of the precharge line 3 and the resistor R1.

  Here, the smoothing capacitor C passes through the resistor R1, the discharge line 5 and the negative line N formed in the precharge line 3 when the fourth switch SW4 of the discharge line 5 is turned on when the ignition switch was turned off last time. The accumulated charge is discharged through the discharge circuit.

  Therefore, the smoothing capacitor C (smoothing capacitor C in a state where the discharge has been completed) immediately before the positive electrode of the DC power source V is connected to the positive electrode of the smoothing capacitor C when the third switch SW3 is turned on has no potential difference between the two electrodes. It has become.

  Further, while the smoothing capacitor C discharges the accumulated charge through the discharge circuit, the positive and negative electrodes of the smoothing capacitor C are connected to the direct current line because the first switch SW1 of the positive line P and the second switch SW2 of the negative line N are off. It is insulated from the positive and negative electrodes of the power supply V.

  For this reason, the potential of the positive electrode and the negative electrode of the smoothing capacitor C, which has no potential difference between the two electrodes due to the end of the discharge, has a potential difference with respect to both the positive electrode and the negative electrode of the DC power supply V.

  Therefore, when the third switch SW3 of the precharge line 3 is switched on and the positive electrode of the smoothing capacitor C is connected to the positive electrode of the DC power supply V, the potential of the positive electrode of the smoothing capacitor C is changed from the same potential as that of the negative electrode to DC. It changes toward the potential of the positive electrode of the power supply V.

  At this time, if the fourth switch SW4 of the discharge line 5 is not fixed on (off) and the electrodes of the smoothing capacitor C are insulated from each other, the potential of the negative electrode of the smoothing capacitor C is the same as that after the end of the discharge. Kept at potential. Therefore, the potential difference between both electrodes of the smoothing capacitor C changes according to the change in the potential of the positive electrode of the smoothing capacitor C.

  On the other hand, if the fourth switch SW4 of the discharge line 5 is fixed on and both electrodes of the smoothing capacitor C are short-circuited by the fourth switch SW4, the positive electrode of the smoothing capacitor C is connected to the positive electrode of the DC power source V. When the potential changes, the potential of the negative electrode of the smoothing capacitor C changes in the same way, and the potential difference between both electrodes of the smoothing capacitor C does not change.

  Therefore, in the charging / discharging device 1 of the present embodiment, the smoothing from the time when the motor controller 9 switches on the third switch SW3 from the state where all of the first to fourth switches SW1 to SW4 are turned off on control is performed. The voltage sensor 7 measures the transition of the potential difference between the two poles of the capacitor C.

  Then, the motor controller 9 determines that the fourth switch SW4 is not fixed on when the potential difference between both electrodes of the smoothing capacitor C is changed, and if not, the fourth switch SW4 is fixed on. Judge.

  That is, the motor controller 9 confirms whether or not the potential difference between both electrodes of the smoothing capacitor C, which the voltage sensor 7 has started to measure from the time when the third switch SW3 is turned on, is changed in step S03 in FIG. .

  If the potential difference between both electrodes of the smoothing capacitor C has not changed (NO in step S03), the motor controller 9 determines that the fourth switch SW4 is fixed on, and determines the failure of the fourth switch SW4. (Step S05), and the smoothing capacitor C precharge processing sequence is terminated.

  On the other hand, if the potential difference between both electrodes of the smoothing capacitor C has changed (YES in step S03), the motor controller 9 determines that the fourth switch SW4 is not fixed on, and the negative line N 2 Switch SW2 is switched on (step S07). Then, the precharge process is executed in the procedure after step S3 in FIG.

  Thereby, the motor controller 9 controls the third switch SW3 and the second switch SW2 to be turned on for the precharge process, so that the DC power supply V is supplied via the fourth switch SW4 of the discharge line 5 that is fixed on. Can be prevented from short-circuiting.

  In the first embodiment described above, the precharge line 3 is connected in parallel with the portion of the positive electrode line P that supplies the power of the DC power supply V to the inverter INV where the first switch SW1 is provided. However, like the charging / discharging device 13 according to the second embodiment of the present invention applied to the electric power control device for the electric vehicle shown in the explanatory diagram of FIG. 12, the portion of the negative electrode line N provided with the second switch SW2 is pre-set. The charge lines 3 may be connected in parallel.

  In this case, the discharge line 5 is connected to the negative electrode side of the smoothing capacitor C with respect to the third switch SW3 of the precharge line 3. Further, the discharge line 5 is connected to the positive electrode side of the smoothing capacitor C rather than the first switch SW1 of the positive electrode line P. Accordingly, the fourth switch SW4 of the discharge line 5 is connected in series with the third switch SW3 of the precharge line 3 with respect to the DC power supply V.

  The resistor R1 is provided on the negative electrode side of the smoothing capacitor C with respect to the connection portion of the precharge line 3 to the discharge line 5. Therefore, the series circuit of the smoothing capacitor C and the resistor R1 is connected in parallel with the discharge line 5 with respect to the DC power supply V.

  When precharging the smoothing capacitor C in the charging / discharging device 13, when an ignition switch (not shown) is turned on, the motor controller 9 switches from the state where all the first to fourth switches SW1 to SW4 are turned off to the positive electrode. The first switch SW1 on the line P and the third switch SW3 on the precharge line 3 are switched on.

  Thus, a precharge circuit is formed which returns to the DC power supply V via the DC power supply V, the first switch SW1 of the positive line P, the smoothing capacitor C, the resistor R1 of the precharge line 3, and the third switch SW3.

  The motor controller 9 turns off the third switch SW3 of the precharge line 3 when the potential difference between both electrodes of the smoothing capacitor C measured by the voltage sensor 7 is sufficiently increased and the smoothing capacitor C is precharged. Then, the second switch SW2 of the negative line N is turned on to switch from the precharge process to the normal power supply state.

  Further, when discharging the accumulated charge of the smoothing capacitor C, when an ignition switch (not shown) is turned off, the motor controller 9 switches from the state where all the first to fourth switches SW1 to SW4 are turned off to the discharge line 5. The fourth switch SW4 is turned on.

  This forms a discharge circuit that returns to the negative electrode of the smoothing capacitor C through the positive electrode of the smoothing capacitor C, the positive electrode line P, the fourth switch SW4 of the discharge line 5, and the resistor R1 of the precharge line 3.

  The motor controller 9 turns off the fourth switch SW4 of the discharge line 5 when the potential difference between the two electrodes of the smoothing capacitor C measured by the voltage sensor 7 has sufficiently decreased and the smoothing capacitor C has sufficiently discharged the accumulated charge. Then, the discharge process is terminated.

  When pre-charging the smoothing capacitor C and performing the on-fixation diagnosis of the fourth switch SW4, the motor controller 9 switches the first to fourth switches SW1 to SW4 when the ignition switch (not shown) is turned off. The third switch SW3 of the precharge line 3 is switched on from the state where all are turned off.

  Then, the potential of the negative electrode of the smoothing capacitor C, which has no potential difference with the positive electrode due to the end of the discharge, changes toward the negative electrode potential (0 V) of the DC power supply V connected when the third switch SW3 is turned on.

  Therefore, the motor controller 9 connects the negative electrode potential of the smoothing capacitor C that changes from the potential at the end of discharge to the negative electrode potential of the DC power source V and the positive electrode potential of the smoothing capacitor C by connecting to the negative electrode of the DC power source V. Whether or not the fourth switch SW4 is on-fixed is determined depending on whether or not the potential difference changes.

  For this purpose, the motor controller 9 changes the potential difference between the two electrodes of the smoothing capacitor C from the time point when the first to fourth switches SW1 to SW4 are all turned off for control and the third switch SW3 is turned on. Is measured by the voltage sensor 7.

  When the motor controller 9 determines that the potential difference between the two electrodes of the smoothing capacitor C has changed, the motor controller 9 determines that the fourth switch SW4 is fixed on, and proceeds to a failure determination process for the fourth switch SW4. Then, the precharge process for the smoothing capacitor C is completed.

  Further, when the motor controller 9 determines that the potential difference between both electrodes of the smoothing capacitor C has not changed, the motor switch 9 turns on the fourth switch SW4 to determine that the fourth switch SW4 is not fixed on, and the smoothing capacitor C The precharge process is executed.

  In the charging / discharging device 13 of the second embodiment configured as described above, a high-performance resistive element is used for the pre-charging resistor and the discharging resistor of the smoothing capacitor C as in the charging / discharging device 1 of the first embodiment. Even in the case of using the device, the miniaturization of the device can be realized with the minimum configuration by making it possible to achieve both purposes with one resistor R1.

  Moreover, also by the charging / discharging apparatus 13 of 2nd Embodiment, similarly to the charging / discharging apparatus 1 of 1st Embodiment, the motor controller 9 controls the 1st switch SW1 and 3rd switch SW3 for a precharge process on control. By switching on, it is possible to prevent the DC power supply V from being short-circuited through the fourth switch SW4 of the discharge line 5 that is fixed on.

  In each of the above-described embodiments, a smoothing capacitor that smoothes the power supplied from the DC power source V to the inverter INV in a power control device mounted on an electric vehicle such as an electric vehicle (EV) or a hybrid vehicle (HEV). The case where the present invention is applied to the C charge / discharge devices 1 and 13 has been described.

  However, the present invention can be widely applied to a smoothing capacitor charging / discharging device that smoothes power to a load from a DC power supply.

  INDUSTRIAL APPLICABILITY The present invention can be used in a smoothing capacitor charging / discharging device that smoothes power to a load from a DC power supply.

1,13 Charge / Discharge Device 3 Precharge Line 5 Discharge Line 7 Voltage Sensor 9 Motor Controller (Discharge Control Unit, Precharge Control Unit)
C Smoothing capacitor INV Inverter (load)
M Electric motor N Negative electrode line P Positive electrode line R1 Resistance (resistance element)
SW1 1st switch (shut-off module)
SW2 Second switch (shut-off module)
SW3 3rd switch (precharge switch)
SW4 4th switch (open module, discharge switch)
V DC power supply

Claims (7)

A smoothing capacitor (C) that smoothes the power supplied from the DC power supply (V) and outputs it to the load (INV), and discharges when the power supply from the DC power supply (V) stops;
Shut-off modules (SW1, SW2) capable of shutting off power supply from the DC power supply (V) to the smoothing capacitor (C);
A resistive element connected between the DC power source (V) and the smoothing capacitor (C) in parallel with the shut-off modules (SW1, SW2) and through which current flows when the smoothing capacitor (C) is precharged and discharged. (R1),
An open module (SW4) including the smoothing capacitor (C) and the resistance element (R1) and capable of opening a discharge circuit through which the current during discharge flows;
A charge / discharge device (1, 13).   The charging / discharging device (1, 2) according to claim 1, wherein the open module (SW4) includes a discharge switch (SW4) for opening and closing the discharge circuit, and the discharge switch (SW4) is closed during the discharge. 13).   The charge / discharge device (1, 13) according to claim 2, wherein the discharge switch (SW4) is opened during the precharge.   A precharge switch (SW3) connected in series with the resistance element (R1) and connected in parallel with the cutoff modules (SW1, SW2) between the DC power supply (V) and the smoothing capacitor (C). The discharge switch (SW4) is further connected in series with the precharge switch (SW3) with respect to the DC power supply (V) and in parallel with the resistance element (R1), The said interruption | blocking module (SW1, SW2) interrupts | blocks the electric power supply from the said DC power supply (V) to the said smoothing capacitor (C) at the time of the said discharge, and the said precharge switch (SW3) is open | released. The charge / discharge device as described (1, 13).   At the time of the discharge, the electric power supply from the DC power source (V) to the smoothing capacitor (C) is cut off by the cut-off modules (SW1, SW2) and the precharge switch (SW3) is opened. 5. The charging / discharging device (1) according to claim 4, further comprising a discharge control unit (9) that closes the switch (SW 4) and opens the discharge switch (SW 4) after the smoothing capacitor (C) is discharged. 13).   At the time of the precharge, the power supply from the DC power supply (V) to the smoothing capacitor (C) is cut off by the cut-off modules (SW1, SW2) and the discharge switch (SW4) is opened. The charge switch (SW3) is closed, and the electric power from the DC power supply (V) is supplied to the smoothing capacitor (C) through the precharge switch (SW3), and the precharge of the smoothing capacitor (C) is performed. Later, the precharge switch (SW3) is opened, and the power from the DC power supply (V) is supplied to the smoothing capacitor (C) by the cutoff module (SW1, SW2). The charge / discharge device (1, 13) according to claim 4 or 5, further comprising:   The precharge control unit (9) shuts off the power supply from the DC power supply (V) to the smoothing capacitor (C) by the cut-off modules (SW1, SW2) and the discharge switch (9) during the precharge. When the precharge switch (SW3) is closed with the SW4) being opened, voltage fluctuations according to the difference between the charge stored in the smoothing capacitor (C) and the DC power supply (V) are caused by the smoothing capacitor (C The charge / discharge device (1, 13) according to claim 6, wherein the discharge switch (SW4) is determined to be in an on-fixed state if it does not occur.

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