JPH08168250A - Power converter - Google Patents

Abstract

(57) [Abstract] [Purpose] By using a common resistor to obtain the function of suppressing the inrush current when the power is turned on and the function of discharging to prevent the terminal voltage of the capacitor from rising due to regenerative current, the entire device can be used. Realize downsizing and cost reduction. [Structure] The power conversion device 21 includes a rectifier circuit 23 that receives an output of a three-phase AC power supply 22, and a rectifying output smoothing capacitor 24. Power is supplied to a motor 26 from both ends of the capacitor 24 through an inverter device 25. . An energizing path changeover switch 27 is interposed between the rectifier circuit 23 and the capacitor 24, and a discharge circuit 28 including a series circuit of a resistor 29 and an IGBT 30 is connected to both ends of a series circuit of the capacitor 24 and the path changeover switch 27. . Resistance 29
A diode for flowing a charging current from the rectifier circuit 23 to the capacitor 24 through the resistor 29 between the common connection point of the IGBT 30 and the positive terminal of the capacitor 24 with the energization path switching switch 27 turned off. 31 is connected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter provided with a rectifier circuit for rectifying an AC power supply output and a capacitor for smoothing the rectified output and giving it to a load, particularly a regenerative device such as a motor. The present invention relates to a power conversion device suitable as a power supply device for a load exhibiting a state.

[0002]

2. Description of the Related Art In this type of power converter, it is desirable to suppress the inrush current flowing into the capacitor when the power is turned on, and when the load is a motor, the regenerative current from the motor is required. As a result, the terminal voltage of the capacitor may rise above the allowable voltage, so it is desirable to provide a circuit that discharges such regenerative current.

FIG. 9 shows an example of a conventional power converter that satisfies the above requirements. That is, in FIG. 9, the power conversion device 1 is for smoothing the output of the three-phase full-wave rectifier circuit 3 including a diode bridge circuit provided so as to receive the output of the three-phase AC power supply 2. And a pair of output terminals 1a connected to both ends of the capacitor 4,
The motor 6 which is a load from 1b through the inverter device 5
It is designed to supply power to.

In this case, a rush current suppressing resistor 7 is connected between the positive side output terminal of the rectifying circuit 3 and the positive electrode terminal of the capacitor 4, and is connected in parallel with the resistor 7 such as an electromagnetic switch or a relay switch. A normally closed energizing circuit changeover switch 8 is connected. Further, in parallel with the capacitor 4, a regenerative current discharging resistor 9 and a discharging circuit 11 including a series circuit of a semiconductor switching element capable of self-extinguishing, for example, an IGBT 10, are connected. Further, a diode 12 for suppressing a surge voltage generated due to an inductance component in the system when the IGBT 10 is off is connected to the discharge circuit 11 in parallel with the resistor 9. The diode 12 is connected so that its cathode is on the positive electrode terminal side of the capacitor 4.

In the power conversion device 1 having such a configuration, the energization path selector switch 8 is normally kept on and the IGBT 10 is kept off, but when the power is turned on, the energization path selector switch 8 is kept. Is held in the off state by a control means (not shown). As a result, when the power is turned on, the charging current for the capacitor 4 flows through the resistor 7, and the inrush current can be suppressed. Further, when the terminal voltage of the capacitor 4 becomes equal to or higher than a predetermined threshold value due to the regenerative current from the motor 6, the IGBT 10 is turned on by the control means (not shown), and accordingly, the charged charge of the capacitor 4 is changed. As the regenerative current is consumed in the resistor 9 while being discharged through the resistor 9, it is possible to prevent the terminal voltage of the capacitor 4 from rising above the allowable voltage.

On the other hand, in the past, in addition to the circuit configuration as described above, a reactor, a semiconductor switching element and a diode are combined in the subsequent stage of the rectifier circuit 3 in order to reduce the power source harmonics and increase the output voltage. It is also practiced to provide a boost chopper circuit having a well-known configuration.

[0007]

In the power converter 1 configured as shown in FIG. 9, suppression of inrush current at power-on,
In addition, two resistors 7 and 9 are required for the regenerative current discharge, and as the resistors 7 and 9, a large and expensive one having a large heat capacity must be used, which is a device. It was a cause of increasing the overall size and cost. Further, when the step-up chopper circuit is provided, a semiconductor switching element for the step-up chopper circuit is separately required in addition to the semiconductor switching element (IGBT 10) that constitutes the regenerative current discharging circuit 11, and therefore, also in this case. The cost of the entire device has risen.

The present invention has been made in view of the above circumstances, and an object thereof is to obtain a function of suppressing an inrush current when the power is turned on and a discharge function of preventing an increase in the terminal voltage of the capacitor due to a regenerative current. It is an object of the present invention to provide a power conversion device which can utilize a common resistor for the above, and can realize downsizing of the entire device and cost reduction. Also, when the terminal voltage of the capacitor is boosted, it is not necessary to add a switching element required for boosting the voltage, and from this aspect also downsizing of the entire device and cost reduction are realized. An object of the present invention is to provide a power conversion device capable of doing the above.

[0009]

In order to achieve the above-mentioned object, the present invention provides a power conversion device provided with a rectifying circuit for rectifying an AC power supply output and a capacitor for smoothing the rectified output and giving it to a load. In the above, a switch element interveningly connected to one of a pair of power supply paths connecting the rectifier circuit and the capacitor, and a series circuit of a resistor and a switching element at both ends of the series circuit of the capacitor and the switch element. And a discharge circuit formed by connecting the resistor so that the resistor is located on the switch element side, and connecting a charging current from the rectifier circuit to the capacitor through the resistor when the switch element is off. And a diode provided with the diode (claim 1).

In this case, a reactor may be inserted into one or both of a pair of power supply paths connecting the rectifier circuit and the discharge circuit (claim 2), and a reactor may be provided on the input side of the rectifier circuit. It may be inserted (claim 3).

When the reactor is provided as described above, the switch element is held in the OFF state at the initial charging of the capacitor by the output from the rectifier circuit, and the terminal voltage of the capacitor rises above the set voltage. The operation of turning on and off the switching element at times may be repeated until charging of the capacitor is completed (claim 4).

Further, when the reactor is provided as described above, after connecting the auxiliary switch element in parallel with the resistor, the switching element is turned off and the auxiliary switch element is turned on, and the switching is performed. It can also be configured to perform on / off control of the element (claim 5).

[0013]

In the power converter according to the first aspect of the present invention, for example, the switching element is normally turned on and the switching element is turned off at all times, and the switching element is turned off when the power is turned on. Therefore, in the steady state, the output of the rectifier circuit that rectifies the output of the AC power source is given to the capacitor through the switch element, and the smoothed output of the capacitor is given to the load. Further, when the switch element is turned off at the time of power-on, the diode starts flowing the charging current from the rectifier circuit to the capacitor through the resistor,
Inrush current to the capacitor when the power is turned on is suppressed. Then, for example, if the switch element is returned to the ON state when charging of the capacitor is completed after this, the charging current for the capacitor will flow through the switch element, and the current will not flow through the resistor. In the steady state, it is not necessary to consider the energy loss in the resistance.

In a steady state in which the switch element is turned on, for example, when the terminal voltage of the capacitor rises due to the regenerative current from the load, the switching element in the discharge circuit is turned on only during that time. Switch. When such switching is performed, the charged electric charge of the capacitor is discharged through the switch element, the resistor and the switching element, and the regenerative current is consumed in the resistor, so that the terminal voltage of the capacitor is equal to or higher than the allowable voltage. The situation that rises to the next level will be prevented.

In the power converter according to the second aspect of the present invention, since the reactor is inserted in one or both of the pair of power feeding paths that connect the rectifying circuit and the discharging circuit, the reactor causes a rush when the power is turned on. The current peak can be suppressed. For this reason, the switch element can be returned to the ON state at a stage before the charging of the capacitor is completed, and the initial charging time can be shortened.

In the power converter according to the third aspect of the present invention, since the reactor is inserted on the input side of the rectifier circuit, the peak of the inrush current when the power is turned on can be suppressed and the initial charging period can be shortened. The AC power line current waveform can be approximated to a sine wave.

According to another aspect of the power converter of the present invention, the switch element is held in the off state during the initial charging of the capacitor by the output from the rectifier circuit, so that the charging current to the capacitor flows through the resistor. become,
Inrush current to the capacitor when the power is turned on is suppressed. After that, when the terminal voltage of the capacitor rises above the set voltage, that is, when the charging current of the capacitor is reduced, the operation of turning on / off the switching element in the discharge circuit is performed until the charging of the capacitor is completed. It will be repeated.

Then, the current input through the reactor increases during the ON period of the switching element, and the energy stored in the reactor increases during the OFF period of the switching element after the input current has increased. Will flow into the battery as a charging current. As a result, the initial charging current for the capacitor does not become extremely small, which makes it possible to accelerate the shortening of the initial charging period.

According to another aspect of the power conversion device of the present invention, the on / off control of the switching element is performed with the switch element turned off and the auxiliary switch element turned on. Then, the energy accumulated in the reactor during the ON period of the switching element flows into the capacitor as the charging current via the diode during the OFF period of the switching element, and the terminal voltage of the capacitor is boosted. .

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. In FIG. 1 showing an electric circuit configuration, a power converter 21 includes a three-phase full-wave rectifier circuit 23 including a diode bridge circuit provided so as to receive an output of a three-phase AC power source 22 via input terminals 21a to 21c. , A capacitor 24 for smoothing the output of the rectifier circuit 23, and a pair of output terminals 21d, 21e connected to both ends of the capacitor 24.
From the inverter 26 via the motor 26 which is a load
It is designed to supply power to.

In this case, the rectifying circuit 23 and the capacitor 24
Of the pair of power supply paths that connect between the
An energization path changeover switch 27 (corresponding to a switch element in the present invention), which is composed of, for example, an electromagnetic switch or a relay switch, is interposed between the positive side output terminal of 1) and the positive terminal of the capacitor 24. A discharge circuit 28 for causing a regenerative current from the motor 26 to flow into both ends (corresponding to the positive and negative output terminals of the rectifier circuit 23) of the series circuit of the capacitor 24 and the passage changeover switch 27. Connected. In this case, the discharge circuit 28 includes a resistor 29 and an I
It is composed of a series circuit between the collector and emitter of the GBT 30 (corresponding to the switching element in the present invention), and the resistor 29 is connected so as to be located on the side of the energization path changeover switch 27.

Further, a diode 31 is connected between the common connection point of the resistor 29 and the IGBT 30 (collector of the IGBT 30) and the positive terminal of the capacitor 24 so that the cathode is on the positive terminal side of the capacitor 24.
As a result, the charging current from the rectifying circuit 23 to the capacitor 24 flows through the resistor 29 and the diode 31 when the energizing path changeover switch 27 is turned off.

The power converter 21 configured as described above.
In this case, the energization path changeover switch 27 is kept on and the IGBT 30 is kept off at all times. When the power is turned on, the energization path changeover switch 27 is turned off by a control means (not shown), and when the capacitor 24 is charged to a predetermined level (for example, the level at which the charging is almost completed), the energization path is switched on. The changeover switch 27 is returned to the ON state. As a result, the charging current from the rectifier circuit 23 to the capacitor 24 flows through the resistor 29 and the diode 31 during the period in which the capacitor 24 is initially charged when the power is turned on.

When the charging of the capacitor 24 is started in this way, the charging current and the terminal voltage of the capacitor 24 change as shown in FIG. As shown in FIG. 2, the charging current for the capacitor 24 rapidly increases immediately after the power is turned on, reaches the maximum value, and then gradually decreases. This maximum current value is almost determined by a value obtained by dividing the output voltage of the rectifier circuit 23 by the resistance value of the resistor 29. Therefore, by appropriately selecting the resistance value of the resistor 29, the capacitor 24 at the time of power-on is turned on. It becomes possible to suppress the inrush current to the.

After this, when the capacitor 24 is charged to a predetermined level, the energizing path changeover switch 27
Returns to the on state and both ends of the resistor 29 are short-circuited, so that it is not necessary to consider the energy loss in the resistor 29 in the steady state.

On the other hand, when the terminal voltage of the capacitor 24 rises above the set upper limit value due to the regenerative current from the motor 26 in the steady state in which the energizing circuit changeover switch 27 is turned on, the discharge circuit 28 is supplied through the control means not shown. The IGBT 30 therein is turned on. Then, the charge charged in the capacitor 24 is discharged through the conduction path changeover switch 27, the resistor 29, and the IGBT 30, and the regenerative current is consumed in the resistor 29.
The situation in which the terminal voltage of the capacitor 24 rises above the allowable voltage is prevented in advance. In this case, the IG
The BT 30 is turned off when the terminal voltage of the capacitor 24 is sufficiently lowered, and accordingly the function of the discharging circuit 28 is returned to the original state in which the function of the discharging circuit 28 is stopped.

When the IGBT 30 is off, there is some inductance component in the resistor 29 so that a current flows continuously, but this current circulates through the diode 31 and the energization path changeover switch 27. Therefore, there is no fear that a large surge voltage is applied between the collector and the emitter of the IGBT 30.

In summary, the present embodiment described above utilizes the common resistor 29 in order to obtain the function of suppressing the inrush current when the power is turned on and the function of discharging to prevent the terminal voltage of the capacitor 24 from rising due to the regenerative current. It has a major feature in that it is configured to do so. As a result of adopting such a configuration, according to the present embodiment, the resistance which requires a large heat capacity is
The number can be reduced from one to one, and the miniaturization of the entire device and cost reduction can be realized.

In the first embodiment, of the pair of power feeding paths connecting the rectifying circuit 23 and the capacitor 24, the power feeding path is provided between the positive side output terminal of the rectifying circuit 23 and the positive terminal of the capacitor 24. Although the changeover switch 27 is interposed, as shown in FIG. 3 showing the second embodiment of the present invention, the energization path changeover switch 27 is provided between the negative side output terminal of the rectifier circuit 23 and the negative terminal of the capacitor 24. The same effect can be obtained even with the interposition. However, in this case, the arrangement of the resistor 29 and the IGBT 30 in the discharge circuit 28 is opposite to that in the first embodiment, and the diode 31 has a common connection point (emitter of the IGBT 30) of the resistor 29 and the IGBT 30 and a negative terminal of the capacitor 24. Is connected so that the anode is on the negative electrode terminal side of the capacitor 24.

FIG. 4 and FIG. 5 show a third embodiment of the present invention, and only the parts different from the first embodiment will be described below. That is, in the present embodiment, as shown in FIG. 4, one of a pair of power supply paths connecting the rectifier circuit 23 and the discharge circuit 28, for example, between the positive output terminal of the rectifier circuit 23 and the discharge circuit 28. It is characterized by the configuration in which the reactor 32 is inserted. Further, in the present embodiment, during the initial charging period of the capacitor 24 (the off period of the energization path switching switch 27) when the power is turned on, the time when the charging current of the capacitor 24 decreases below the set current, that is, the terminal voltage of the capacitor 24 changes. When the voltage rises above the set voltage, the operation of turning on the IGBT 30 and then turning off the IGBT 30 when the input current through the reactor 32 increases is repeated until the charging of the capacitor 24 is completed. There is.

In this embodiment having such a structure, the presence of the reactor 32 makes it possible to suppress the peak of the inrush current when the power is turned on.
Before the charging of 4 is completed, the energizing circuit changeover switch 2
7 can be returned to the ON state, and as a result, the initial charging period can be shortened and the loss in the resistor 29 can be suppressed as much as possible.

During the initial charging of the capacitor 24 when the power is turned on, the energizing path changeover switch 27 is turned off when the charging current for the capacitor 24 is the capacitor 24 and the resistor 29 as shown in FIG. Although it gradually decreases at a rate according to the constant, in the present embodiment, the IGBT 30 is turned on when the charging current decreases below the set current, the input current through the reactor 32 increases, and such an increase in the input current occurs. Later, the IGBT 30 is turned off, and the energy stored in the reactor 32 flows into the capacitor 24 as a charging current. As a result, the initial charging current for the capacitor 24 does not become extremely small, and in this respect as well, the reduction of the initial charging period can be promoted.

Further, in the present embodiment, the peak of the input current is suppressed and the effective value of the rectifier circuit is reduced due to the presence of the reactor 32 even during the steady operation in which the energization path changeover switch 27 is returned to the ON state. The conduction loss of the capacitor 23 is reduced, and the ripple current in the capacitor 24 is reduced, so that the temperature rise of the capacitor 24 is reduced.

Moreover, in the structure in which the reactor 32 is provided as described above, the harmonic current flowing in the AC power line from the three-phase AC power source 22 also decreases. Specifically, when the reactor 32 is provided as in the present embodiment, the AC power line current waveform per line becomes the state shown by the solid line in FIG. 5 and the harmonic current decreases. In FIG. 5, the AC power line current waveform when the reactor 32 is not provided is shown by a broken line). As a result, harmonic interference with other devices receiving power from the three-phase AC power supply 22 can be reduced.

In the third embodiment, the reactor 32 is inserted into one of the pair of power feed paths connecting the rectifier circuit 23 and the discharge circuit 28. However, the reactor is inserted into the other of the power feed paths. Alternatively, the same effect can be obtained even if the reactor is inserted in both power supply paths. In particular, when the reactor is inserted in both of the pair of power supply paths that connect the rectifier circuit 23 and the discharge circuit 28, switching noise generated in the IGBT 30 and the inverter device 25 and flowing out to the three-phase AC power supply 22 side is generated. The effect of reduction is obtained.

FIG. 6 shows a fourth embodiment of the present invention, and only the parts different from the first embodiment will be described below. That is, as shown in FIG. 6, the present embodiment is characterized in that the reactor 33 is inserted in the input side of the rectifier circuit 23, that is, in each of the three AC power lines from the three-phase AC power supply 22.

Also in this embodiment having such a configuration,
The peak of the inrush current at the time of turning on the power can be suppressed, the initial charging period can be shortened, and the AC power line current waveform can be approximated to a sine wave. In the case of the configuration of this embodiment, the terminal voltage of the capacitor 24 during the steady operation also decreases with the decrease of the AC voltage applied to the rectifier circuit 23. In such a situation, If the reactor 32 as in the third embodiment is inserted in the output side of the rectifier circuit 23, it can be improved to some extent.

FIG. 7 shows a fifth embodiment of the present invention, which is a modification of the above fourth embodiment, and will be described below. That is, as shown in FIG. 7, the present embodiment is characterized in that the auxiliary changeover switch 34 (corresponding to the auxiliary switch element in the present invention) composed of an electromagnetic switch or a relay switch is connected in parallel with the resistor 29. in this case,
The auxiliary changeover switch 34 is turned off during the initial charge period and the discharge period of the capacitor 24, and when the terminal voltage of the capacitor 24 is boosted or when the harmonic component of the AC power line current is reduced, the auxiliary switch 34 is turned on. The switching control is performed such that the IGBT 30 is periodically turned on and off with the electric path changeover switch 27 turned off and the auxiliary changeover switch 34 turned on.

When such switching control is performed, the energy stored in the reactor 33 during the ON period of the IGBT 30 begins to flow into the capacitor 24 as a charging current via the diode 31 during the OFF period of the IGBT 30, and By capacitor 2
The terminal voltage of 4 is boosted. In this case, if the output current from the rectifier circuit 23 is adjusted to be substantially constant while the inductance of the reactor 33 is set to be relatively small, the AC power line current waveform becomes the state shown in FIG. Therefore, in this case, even if the reactor 33 is downsized, the harmonic components of the AC power line current can be suppressed, and the conduction loss in the rectifier circuit 23 and the ripple current in the capacitor 24 can be reduced. Become.

As a result, there is no problem even if the reactor 33 is miniaturized, the capacity of the capacitor 24 can be reduced, and a self-turn-off semiconductor switching element for boosting the terminal voltage of the capacitor 24 is provided. , The IGB originally provided in the discharge circuit 28
Since the T30 can also be used, it is possible to realize the downsizing of the entire apparatus and the reduction of cost.
Furthermore, as a result of the boosting function being added as described above, the output voltage when the motor 26 is driven can be increased to suppress the load current in the state where the motor 26 is rotated at high speed. Also, the loss in the inverter device 25 can be reduced.

Although the reactor 33 is provided on the AC side in this embodiment, the same effect as described above can be obtained by using the reactor on the DC side as in the third embodiment. It is a thing.

In addition, the present invention is not limited to the above embodiment, and the following modifications and expansions are possible. As in the second embodiment shown in FIG. 3, the configuration in which the conduction path changeover switch 27 is interposed between the negative side output terminal of the rectifier circuit 23 and the negative terminal of the capacitor 24 is shown in FIGS.
It is also possible to apply to each circuit configuration of FIG. Although the IGBT 30 which is a semiconductor switching element capable of self-extinguishing is used as the switching element, other semiconductor switching elements may be used, and the output voltage of the capacitor 24 may be utilized by using the semiconductor switching element. When it is not necessary to boost the voltage, a mechanical switch such as an electromagnetic switch or a relay switch can be used as the switching element.

[0043]

As is apparent from the above description, according to the invention described in claim 1, the function of suppressing the inrush current when the power is turned on and the function of discharging to prevent the terminal voltage of the capacitor from rising due to the regenerative current are provided. Since the configuration is obtained by using a common resistor, it is possible to realize the downsizing of the entire device and the cost reduction. Of course, it is not necessary to consider the energy loss in the resistor in the steady state. is there.

According to the second aspect of the present invention, the reactor is inserted into one or both of the pair of feed lines of the rectifier circuit, and the third aspect of the present invention is such that the reactor is inserted into the input side of the rectifier circuit. The peak of the inrush current at the time of turning on the power can be suppressed and the initial charging period can be shortened.

According to the fourth aspect of the present invention, the operation of turning on / off the switching element in the discharge circuit when the terminal voltage of the capacitor rises above the set voltage during the initial charging of the capacitor by the output from the rectifier circuit, Since the energy stored in the reactor is made to flow into the capacitor as charging current by repeating the configuration until the capacitor is completely charged, the initial charging current for the capacitor does not become extremely small, It becomes possible to promote shortening of the charging period.

In the power converter according to the fifth aspect of the present invention, when the terminal voltage of the capacitor can be boosted, a switching element required for boosting the voltage and a switching element provided for discharging the regenerative current are provided. Since it is configured to be used for both, it is not necessary to newly add a switching element, and from this aspect, it is possible to realize the downsizing of the entire device and the cost reduction.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an example of changes in capacitor charging current and terminal voltage.

FIG. 3 is a circuit configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram showing a third embodiment of the present invention.

FIG. 5 is a diagram showing an AC power line current waveform.

FIG. 6 is a circuit configuration diagram showing a fourth embodiment of the present invention.

FIG. 7 is a circuit configuration diagram showing a fifth embodiment of the present invention.

FIG. 8 is a diagram showing an AC power line current waveform.

FIG. 9 is a circuit configuration diagram showing a conventional example.

[Explanation of symbols]

In the drawing, 21 is a power converter, 22 is a three-phase AC power supply, and 2
3 is a three-phase full-wave rectifier circuit, 24 is a capacitor, 25 is an inverter device, 26 is a motor (load), 27 is an energization path changeover switch (switch element), 28 is a discharge circuit, 29 is a resistor, and 30 is an IGBT (switching). 31) is a diode, 32 and 33 are reactors, and 34 is an auxiliary changeover switch (auxiliary switch element).

Claims (5)

[Claims] 1. A power conversion device comprising a rectifier circuit for rectifying an AC power supply output and a capacitor for smoothing the rectified output and applying the rectified output to a load, wherein a pair of power feeds connecting the rectifier circuit and the capacitor. A switch element that is interposed in one of the paths so that it can be intermittently connected, and both ends of the series circuit of the capacitor and the switch element
A discharge circuit formed by connecting a series circuit of a resistor and a switching element such that the resistor is located on the switch element side; and a charging current from the rectifier circuit to the capacitor when the switch element is off. And a diode connected so as to flow through the power converter. 2. The power conversion device according to claim 1, wherein a reactor is inserted in one or both of a pair of power supply paths that connect the rectifier circuit and the discharge circuit. 3. The power converter according to claim 1, wherein a reactor is inserted on the input side of the rectifier circuit. 4. An operation of holding the switch element in an off state at the time of initial charging of the capacitor by an output from the rectifier circuit and turning on / off the switching element when a terminal voltage of the capacitor rises above a set voltage. The power conversion device according to claim 2 or 3, wherein the above is repeated until charging of the capacitor is completed. 5. An auxiliary switch element is connected in parallel with the resistor, and the switching element is turned on and off in a state in which the switch element is turned off and the auxiliary switch element is turned on. The power conversion device according to claim 2 or 3.