JP5528858B2 - Power converter - Google Patents

Description

  The present invention provides a grid-connected inverter device provided between a DC power source such as a secondary battery, a solar battery, or a fuel cell and a power system, or a DC load driven by DC power and a power system. The present invention relates to a power conversion device including a converter device.

  In a grid-connected inverter device or the like provided between a DC power source such as a secondary battery, a solar cell, or a fuel cell and a commercial power system, the DC power obtained from the DC power source is switched by the switching operation of the inverter circuit. It is converted into three-phase AC power suitable for the electric power system and is inserted into the electric power system.

  By the way, a DC side capacitor is connected between the DC power supply and the inverter circuit to smooth the DC power input from the DC power supply to the inverter circuit. If the DC side capacitor is not sufficiently charged when connecting the inverter circuit and the power system, for example, if the inverter circuit and the power system are connected first, the inverter from the power system There is a risk that excessive inrush current will occur in the DC side capacitor via the diode, which is reversely connected to the semiconductor switching element that constitutes the circuit, more specifically the inverter circuit, causing damage to the switching element and noise in the power system. It was. In the case where the DC power supply and the inverter circuit are connected first, an excessive inrush current is generated from the DC power supply to the DC-side capacitor, which may cause damage to the DC power supply.

  Therefore, for example, the apparatus disclosed in Patent Document 1 includes an initial charging circuit that performs initial charging of the DC-side capacitor while the inverter circuit is stopped before starting the fuel cell. The initial charging circuit draws in AC power from the power system based on the turning on of the charging switch, converts it into predetermined DC power via a rectifier circuit and a charging resistor, and supplies it to the DC side capacitor. Is to do. Then, the fuel cell is started after waiting for the charging of the DC side capacitor, and after the fuel cell is started, the inverter circuit is operated using the power of the fuel cell and the interconnection switch is turned on, so that the fuel cell side Generation of an excessive inrush current as described above is prevented.

JP-A-8-321319

  By the way, although not illustrated in Patent Document 1, a filter circuit including a coil and a capacitor that passes AC power of a system frequency on the output side of the inverter circuit and absorbs AC power other than the system frequency as noise is provided. However, if the filter capacitor is not sufficiently charged, an inrush current is generated when the interconnection switch is turned on, and a large noise is generated in the power system.

  In Patent Document 1, since the switching operation of the inverter circuit is started before the interconnection switch is turned on, if a filter circuit (filter capacitor) is provided on the output side of the inverter circuit, the operation of the inverter circuit is not performed. The filter capacitor can be charged in advance, but in the case where it is replaced with a DC power source with a slow rise like a fuel cell, or a DC power source such as a secondary battery or a solar cell that can sometimes have zero voltage. In particular, if the inverter circuit is simply operated before turning on the interconnection switch, the voltage and phase before and after the interconnection switch cannot be adjusted due to insufficient charge of the filter capacitor due to insufficient power supply from the DC power supply. There was a risk that an inrush current would occur when the switch was turned on.

  In addition, when the DC capacitor is charged by the initial charging circuit described above, for example, by switching the inverter circuit, the filter capacitor is charged without involving the DC power supply, so the reliability is improved. , The charging voltage is reduced by the voltage drop across the charging resistor of the initial charging circuit, and an inrush current still occurs when the interconnection switch is turned on.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a power converter that can sufficiently suppress an inrush current generated in a starting process.

In order to solve the above problems, the invention according to claim 1 is provided between a DC power source in which DC power is generated or a DC load driven by DC power and a power system in which three-phase AC power flows, A power converter provided with a switching circuit for performing DC-AC conversion or AC-DC conversion between each other, a connection switch for connecting the DC power source or the DC load and the switching circuit, and the switching circuit An interconnection switch for connecting to the electric power system; a DC-side capacitor for smoothing the DC power between the connection switch and the switching circuit; and a predetermined frequency between the switching circuit and the interconnection switch. A filter capacitor constituting a filter circuit for passing the AC power in the band, and An initial charging circuit that rectifies AC power from the power system that is input without going through a switch to generate DC power, and supplies the generated DC power to the DC capacitor via a charging resistor for charging. And at the time of start-up, first the connection switch and the interconnection switch are turned off to generate DC power by the rectification operation of the initial charging circuit and the operation of the switching circuit to charge the DC-side capacitor, and Charging the filter capacitor via the switching circuit, and then when each capacitor rises to a predetermined charging voltage, the switching circuit is temporarily stopped to further charge the DC side capacitor to the rectified voltage of the power system, then in said switching circuit according to on of the previous SL interconnection switch and connection to the power system, the connection Sui When the DC power supply or the DC load and the switching circuit are connected by turning on the switch, the operation of the switching circuit is restarted, and the DC power supply or the DC load and the power system are connected via the switching circuit. A startup control unit that controls the connection to achieve the connection, and the startup control unit stops the switching circuit at a timing at which a zero crossing of any one-phase AC voltage occurs, and thereafter When the system switch is turned on , the gist is that it is turned on at the timing of the zero-crossing of the AC voltage in phase with the stop state and connected to the power system .

In this invention, at the time of start-up, first, the connection switch between the DC power source or the DC load and the interconnection switch between the power system are turned off, the generation of the DC power in the initial charging circuit and the switching circuit The DC capacitor is charged and the filter capacitor is charged via the switching circuit. Next, when each capacitor rises to a predetermined charging voltage, the switching circuit is temporarily stopped and the DC side capacitor is further charged to the rectified voltage of the power system. Then, a connection between the switching circuit and the power system due to the turn-on of the interconnection switch at the timing of the zero crossing of the AC voltage is stopped during the same phase of the switching circuits, a DC power supply or a DC load and a switching circuit according to on of the connection switch And restarting the operation of the switching circuit, and the connection between the DC power source or the DC load and the power system through the switching circuit is performed satisfactorily. That is, when the interconnection switch is turned on, the DC side capacitor is precharged up to the rectified voltage of the power system, so that almost no inrush current flows from the power system side to the DC side capacitor via the inverter circuit. Further, the charging is performed by operating the switching circuit at a time even in the filter capacitor, after temporarily stopping the switching circuit due to an increase in the charging voltage of the DC side capacitor, communication at a timing when the zero crossing of the AC voltage of the stop and the phase Since the system switch is turned on, the potential difference between the charging voltage of the filter capacitor for each phase at the time of turning on and the AC voltage of each phase of the power system is extremely small, and the inrush current toward the filter capacitor is suppressed to be extremely small. As a result, the burden on the switching elements of the inverter circuit can be reduced, and the change (noise) in the system current can be sufficiently suppressed.

  In the present invention, when the switching circuit is temporarily stopped, it is stopped at the timing when any one-phase AC voltage is zero-crossed, and when the subsequent interconnection switch is turned on, the AC voltage is zero-crossed in the same phase as when the switching is stopped. It is turned on at the timing to connect to the power system. In other words, since the potential difference between the charging voltage of the filter capacitor for each phase and the AC voltage of each phase of the power system when the interconnection switch is on is minimized at zero crossing, the inrush current toward the filter capacitor can be minimized. .

The invention according to claim 2, in the power conversion device according to claim 1, wherein the starting control means, the timing of stopping the charging of the capacitor was set later than the timing of turning on the interconnection switch Is the gist.

  In the present invention, the timing for stopping the charging of the capacitor is set after the timing for turning on the interconnection switch. As a result, the inrush current that is generated when the capacitor on the direct current side is slightly discharged preceded by the timing of stopping charging of the capacitor is surely prevented.

According to a third aspect of the present invention, in the power conversion device according to the first or second aspect , the start-up control means sets a timing for turning on the connection switch after a timing for turning on the interconnection switch. This is the gist.

  In the present invention, the timing for turning on the connection switch is set after the timing for turning on the interconnection switch. As a result, the inrush current that is generated when the direct current side capacitor is slightly discharged first when the connection switch is turned on is surely prevented.

The invention according to claim 4, in the power conversion apparatus according to any one of claims 1 to 3, a DC power supply DC power occurs, provided between the electric power system through which 3-phase AC power, The gist of the present invention is that it is constituted by a grid-connected inverter device including an inverter circuit that performs DC-AC conversion between each other.

  According to the present invention, in a grid-connected inverter device provided between a DC power supply and a power system, an inrush current generated when connecting to the power system at startup is sufficiently suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the power converter device which can fully suppress the inrush current which arises in a starting process can be provided.

It is a circuit diagram which shows the power converter device in this embodiment. It is a voltage-current waveform figure of each location accompanying operation | movement of a power converter device.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
FIG. 1 shows a grid interconnection inverter device 10 as a power conversion device of the present embodiment. The grid-connected inverter device 10 of the present embodiment is provided between the secondary battery 11 and the power system 12, and the DC power of the secondary battery 11 is converted into commercial three-phase (U phase, V phase, W phase) AC. It is configured as a device that converts power. An AC load 13 driven by three-phase AC power is connected to the power system 12.

  The grid interconnection inverter device 10 includes an inverter circuit 20 formed of a full bridge of a semiconductor switching element Tr such as an IGBT in order to perform DC-AC power conversion. The input side of the inverter circuit 20 is connected to the secondary battery 11 via the connection switch 21. The connection switch 21 is controlled to be turned on and off by the control circuit 30 so that the connection timing between the inverter circuit 20 and the secondary battery 11 is optimized. Between the connection switch 21 and the inverter circuit 20, a DC-side capacitor C1 that smoothes DC power from the secondary battery 11 is provided. The inverter circuit 20 converts the input DC power into predetermined three-phase AC power suitable for the power system 12 based on the ON / OFF operation of the switching element Tr by PWM control of the control circuit 30.

  The output side of the inverter circuit 20 is connected to the power system 12 via the filter circuit 22 and the interconnection switch 23. The filter circuit 22 and the interconnection switch 23 are provided for each of the U phase, the V phase, and the W phase. The filter circuit 22 is composed of a low-pass filter circuit (LPF circuit) in which a capacitor (filter capacitor) C2 is connected between the two coils L1 and L2, and the AC circuit outputs the AC power output from the inverter circuit 20. Among them, AC power having a system frequency (50 Hz or 60 Hz) conforming to the commercial power system 12 is passed, and power in a frequency band not conforming to the power system 12 is absorbed as noise. The connection switch 23 is controlled to be turned on and off by the control circuit 30, and the connection timing between the inverter circuit 20 and the power system 12 is optimized.

  Further, the grid interconnection inverter device 10 is provided with an initial charging circuit 24. The initial charging circuit 24 includes a charging switch 25, a rectifying circuit 26, and a charging resistor (current limiting resistor) R1. The input side of the rectifier circuit 26 is connected between the interconnection switch 23 and the power system 12, and the output side of the rectifier circuit 26 is connected between the connection switch 21 and the inverter circuit 20 via the charging resistor R1. . On / off of the charging switch 25 is controlled by the control circuit 30, and the charging operation in the circuit 30 is controlled. While the charging switch 25 is on, the rectifier circuit 26 composed of a full-wave rectifier circuit converts the AC power of the power system 12 into DC power, and supplies the DC power to the inverter circuit 20 side.

  The grid-connected inverter device 10 is provided with a DC voltage sensor 27 between the connection switch 21 and the inverter circuit 20, and a detection signal corresponding to the detected DC voltage is input to the control circuit 30. Further, an AC voltage sensor 28 is provided between the interconnection switch 23 and the power system 12, and a detection signal for each phase corresponding to the detected AC voltage is input to the control circuit 30. Furthermore, a start switch 29 for starting the grid-connected inverter device 10 is provided, and a start signal from the switch 29 is input to the control circuit 30.

  The control circuit 30 starts the operation related to the grid connection of the grid interconnection inverter device 10 based on the input of the activation signal from the activation switch 29. In the following, description will be made with reference to the operating states of the switches 21, 23 and 25 and the inverter circuit 20 shown in FIG. 2 and the changes in voltage value and current value at each location. In the present embodiment, the AC voltage of the power system 12 is set to 440 [Vac].

  First, before the start switch 29 is turned on, the connection switch 21, the interconnection switch 23, and the charge switch 25 are all off, and the DC-side capacitor C1 and the filter capacitor C2 are in a discharged state (zero charge voltage).

  <Time t1>: When the start switch 29 is turned on, the control circuit 30 starts the switching operation of the inverter circuit 20. The inverter circuit 20 converts the input DC power into AC power by a switching operation. However, when the connection switch 21 and the charging switch 25 are in the OFF state, there is no DC power input to the inverter circuit 20, and the inverter circuit 20 There is no AC power output.

  <Time t2>: Next, the control circuit 30 turns on the charging switch 25 of the initial charging circuit 24. Then, AC power from the power system 12 is input to the rectifier circuit 26 via the switch 25. The rectifier circuit 26 converts the input AC power into DC power, and the converted DC power is supplied to the inverter circuit 20 via the charging resistor R1. Since the connection switch 21 is turned off, the DC power from the rectifier circuit 26 is not input to the secondary battery 11 side.

  The voltage value of the DC power from the rectifier circuit 26 is gradually increased, and accordingly, the voltage value of the AC power output from the inverter circuit 20 is also gradually increased. As these voltage values rise, the DC side capacitor C1 is charged and its charging voltage gradually rises, and the filter capacitor C2 is also charged and its charging voltage gradually rises.

  Eventually, with respect to the AC voltage 440 [Vac] of the power system 12, the DC side capacitor C1 is charged to a charge voltage (input voltage of the inverter circuit 20) of 570 [Vdc]. The output voltage of the rectifier circuit 26 (the full-wave rectified voltage of the power system 12) is 620 [Vdc]. At this time, the charging voltage of the DC side capacitor C1 is 570, which is a voltage value lower by the voltage drop of the charging resistor R1. Up to [Vdc]. Accordingly, the filter capacitor C2 is charged to a charge voltage (output voltage of the inverter circuit 20) of 400 [Vac].

  <Time t3>: Next, when the rectifier circuit 26 detects that the charging voltage of the DC side capacitor C1 has reached 570 [Vdc] based on the detection of the DC voltage sensor 27, the control circuit 30 The switching operation of the circuit 20 is temporarily stopped. Then, since the DC power from the rectifier circuit 26 is not input to the inverter circuit 20, the DC-side capacitor C1 is further charged to increase the charging voltage, and the output voltage 620 [Vdc] of the rectifier circuit 26, that is, The battery is charged up to the rectified voltage of the power system 12.

  Regarding the stop timing of the inverter circuit 20, the control circuit 30 is configured so that, for example, the U-phase AC voltage is zero-crossed in the AC power output from the inverter circuit 20 based on the detection of the AC voltage sensor 28. 20 switching operation is stopped. Therefore, the filter capacitor C2 for each phase is held in the charged state when the inverter circuit 20 is stopped.

  <Time t4>: Next, when the control circuit 30 detects that the charging voltage of the DC-side capacitor C1 has reached 620 [Vdc] based on the detection of the DC voltage sensor 27, the control circuit 30 is connected The system switch 23 is turned on. In this case, the control circuit 30 turns on the interconnection switch 23 at the timing when the U-phase AC voltage becomes zero crossing, as in the case of the previous stop of the inverter circuit 20. That is, since the filter capacitor C2 of each phase is held in the charged state when the inverter circuit 20 is stopped, the filter capacitor C2 of each phase and the power system 12 side are connected at a timing at which the potential difference is minimized.

  This causes a slight inrush current to the capacitor C2 from a slight potential difference generated between the charging voltage 400 [Vac] of the filter capacitor C2 other than the U-phase and the AC voltage 440 [Vac] of the power system 12, but the potential difference Is set to the minimum, the inrush current is extremely small. In addition, since the charging voltage of the DC side capacitor C1 is charged in advance up to 620 [Vdc] of the rectified voltage of the power system 12 so as not to cause a potential difference, switching from the power system 12 side via the inverter circuit 20 (switching) Inrush current flowing into the DC capacitor C1 side (via a diode reversely connected to the element Tr) hardly occurs.

  Therefore, when the interconnection switch 23 is turned on, the inrush current is suppressed to a slight inrush current corresponding to the amount flowing into the filter capacitor C2, and the inrush current to the DC side capacitor C1 through the inverter circuit 20 is suppressed. As a result, the burden on the switching element Tr and the like of the inverter circuit 20 is reduced, and the change (noise) of the system current is also suppressed to a slight change that flows into the filter capacitor C2.

  <Time t5>: Next, the control circuit 30 turns off the charging switch 25. Then, the supply of DC power from the initial charging circuit 24 to the inverter circuit 20 side is stopped, but the DC voltage generated via the inverter circuit 20 from the power system 12 side based on the previous connection switch 23 being turned on. Thus, the charging voltage of the DC side capacitor C1 is maintained.

  In this case, the charging switch 25 can be turned off at the same time as the connection switch 23 is turned on. However, the charging switch 25 is turned off at a time t5 delayed by a predetermined time from the time t4 when the connection switch 23 is turned on. The charging switch 25 is surely turned off after the connection switch 23 is turned on. In other words, if the charge switch 25 is turned off first, the DC capacitor C1 is slightly discharged, and a slight potential difference is generated from the power system 12 side when the interconnection switch 23 is turned on, so that a slight inrush current via the inverter circuit 20 is generated. Therefore, the charging switch 25 is surely turned off later to prevent the inrush current from occurring.

<Time t6>: Next, the control circuit 30 turns on the connection switch 21. Then, DC power from the secondary battery 11 is supplied to the inverter circuit 20.
In this case, the connection switch 21 is turned on at the same time as the connection switch 23 is turned on. However, when the connection switch 21 is turned on at a time t6 delayed by a predetermined time from the time t4 when the connection switch 23 is turned on. The connection switch 21 is surely turned on after the connection switch 23 is turned on. That is, if the connection switch 21 is turned on first, the DC-side capacitor C1 is slightly discharged, causing a slight potential difference from the power system 12 side when the interconnection switch 23 is turned on. Therefore, the connection switch 21 is surely turned on later to prevent the occurrence of the inrush current.

  <Time t7>: The control circuit 30 resumes the switching operation of the inverter circuit 20. In this case, since the AC voltage from the power system 12 is applied to the output terminal of the inverter circuit 20 based on the previous connection switch 23 being turned on, the control circuit 30 indicates that, for example, the U-phase AC voltage is zero-crossed. At that timing, the switching operation is resumed. As a result, the AC power output from the inverter circuit 20 is input to the power system 12 together.

  In this way, the grid interconnection inverter device 10 is started based on the control of the control circuit 30, and after time t7, the DC voltage and AC voltage values detected by the voltage sensors 27 and 28, respectively. Then, the inverter circuit 20 is switched at an optimal timing based on the phase and the three-phase AC power generated by switching from the DC power of the secondary battery 11 is inserted into the power system 12. ing.

Next, characteristic effects of the present embodiment will be described.
(1) In the present embodiment, at the time of start-up, first, the connection switch 21 between the secondary battery 11 and the interconnection switch 23 between the power system 12 are turned off, and the direct current in the initial charging circuit 24 is Generation of electric power and operation of the inverter circuit 20 are performed to charge the DC-side capacitor C1 and charge the filter capacitor C2 via the inverter circuit 20. Next, when each of the capacitors C1 and C2 rises to a predetermined charging voltage, the inverter circuit 20 is temporarily stopped and the DC side capacitor C1 is further charged to the rectified voltage of the power system 12. Next, the connection between the inverter circuit 20 and the power system 12 when the interconnection switch 23 is turned on at the same timing as when the inverter circuit 20 is stopped, and the connection between the secondary battery 11 and the inverter circuit 20 when the connection switch 21 is turned on. The operation of the inverter circuit 20 is restarted, and the connection between the secondary battery 11 and the power system 12 via the inverter circuit 20 is performed well. That is, when the interconnection switch 23 is turned on, the DC-side capacitor C1 is precharged up to the rectified voltage of the power system 12, so that the inrush current from the power system 12 side to the DC-side capacitor C1 via the inverter circuit 20 is Almost does not occur. Also, the filter capacitor C2 is charged by operating the inverter circuit 20 once. After the inverter circuit 20 is temporarily stopped due to an increase in the charging voltage of the DC side capacitor C1, the interconnection switch 23 is turned on at the same timing as the stop. Since it is turned on, the potential difference between the charging voltage of the filter capacitor C1 for each phase at the time of turning on and the AC voltage of each phase of the power system 12 is extremely small, and the inrush current toward the filter capacitor C1 is also extremely small. As a result, in the grid-connected inverter device 10 of the present embodiment, the burden on the switching element Tr of the inverter circuit 20 and the like can be reduced, and a change (noise) in the grid current can be sufficiently suppressed.

  (2) In the present embodiment, when the inverter circuit 20 is temporarily stopped, the inverter circuit 20 is stopped at the timing when the U-phase AC voltage is zero-crossed, and when the subsequent interconnection switch 23 is turned on, the AC voltage having the same phase as that at the time of the stop It is turned on at the timing of the zero crossing and is connected to the power system 12. That is, since the potential difference between the charging voltage of the filter capacitor C1 for each phase when the interconnection switch 23 is on and the AC voltage of each phase of the power system 12 is zero-crossed, the inrush current toward the filter capacitor C1 is also reduced. It can be minimized.

  (3) In the present embodiment, the timing of turning off the charging switch 25 that stops the charging of the DC side capacitor C1 is set after the timing of turning on the interconnection switch 23. As a result, it is possible to reliably prevent an inrush current that is generated when the capacitor C1 is slightly discharged first when the charging of the DC-side capacitor C1 is stopped first.

  (4) In this embodiment, the timing for turning on the connection switch 21 is set after the timing for turning on the interconnection switch 23. Thus, it is possible to reliably prevent an inrush current that is generated when the DC-side capacitor C1 is slightly discharged toward the secondary battery 11 at the timing when the connection switch 21 is turned on first.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the secondary battery 11 is applied to the grid-connected inverter device 10 in which the DC power source is used. However, as shown by the broken line in FIG. 1, it is replaced with another DC power source such as a solar cell 15 or a fuel cell. You may apply to a grid connection inverter apparatus.

  In addition to the grid-connected inverter device that connects the DC power supply (secondary battery 11 and the like) and the power system 12, the DC power supply is replaced with a DC load 16 driven by DC power, so that the inverter circuit 20 is originally used. It may be applied to a converter device that operates like a converter circuit that performs AC-DC conversion from DC-AC conversion, generates DC power from AC power of the power system 12 and supplies the DC power to the DC load 16.

  In the above embodiment, when the inverter circuit 20 is temporarily stopped, it is stopped at the timing when the U-phase AC voltage is zero-crossed, and when the subsequent interconnection switch 23 is turned on, the zero-cross of the AC voltage in the same phase as when the inverter is stopped However, the zero-cross point of the AC voltage of the V phase and W phase other than the U phase may be used.

  Further, the inverter circuit 20 is temporarily stopped not only at the zero cross point but also at an arbitrary phase, and when the connection switch 23 is subsequently turned on, the connection switch 23 is turned on at the same phase as that at the time of the stop and connected to the power system 12. You may do it.

  In the above embodiment, the configuration of each circuit constituting the grid interconnection inverter device 10 such as the filter circuit 22 and the initial charging circuit 24 may be appropriately changed.

  DESCRIPTION OF SYMBOLS 10 ... Grid connection inverter apparatus, 12 ... Electric power system, 16 ... DC load, 20 ... Inverter circuit (switching circuit), 21 ... Connection switch, 22 ... Filter circuit, 23 ... Connection switch, 24 ... Initial charge circuit, 30 ... control circuit (startup control means), C1 ... DC side capacitor, C2 ... filter capacitor, R1 ... charging resistor.

Claims (4)

A switching circuit that is provided between a DC power source that generates DC power or a DC load driven by DC power and a power system through which three-phase AC power flows, and performs DC-AC conversion or AC-DC conversion between each other. A power conversion device comprising:
A connection switch for connecting the DC power supply or the DC load and the switching circuit; a connection switch for connecting the switching circuit and the power system; and the DC switch between the connection switch and the switching circuit. A DC side capacitor for smoothing the power, and a filter capacitor constituting a filter circuit for passing the AC power in a predetermined frequency band between the switching circuit and the interconnection switch,
AC power from the power system that is input without going through the interconnection switch at the time of start-up is generated to generate DC power, and the generated DC power is supplied to the DC-side capacitor via a charging resistor for charging. With an initial charging circuit to perform,
At the time of starting, first, the connection switch and the interconnection switch are turned off to generate DC power by the rectifying operation of the initial charging circuit and the operation of the switching circuit to charge the DC-side capacitor, and the switching circuit and charges of the filter capacitor through, then the further charging the DC side capacitor temporarily stopping the switching circuit and the capacitor rises to a predetermined charging voltage to the rectified voltage of the electric power system, then at and the switching circuit according to on of the previous SL interconnection switch and connection to the power system, the connection switch the DC power supply or the DC load by turning on the connection with the switching circuit, the resumption of operation of the switching circuit and The DC power supply or the DC load and the power system It includes a starting control means for controlling to reduce the connection through the etching circuit,
When the switching circuit is temporarily stopped, the start-up control means stops at the timing when any one-phase AC voltage becomes a zero cross, and then turns on the interconnection switch when the switching circuit is turned on. A power conversion device that is turned on at a timing at which a voltage zero crossing is established to connect to the power system. The power conversion device according to claim 1 ,
The start-up control means sets the timing for stopping the charging of the DC-side capacitor after the timing for turning on the interconnection switch. The power conversion device according to claim 1 or 2 ,
The start-up control means sets the timing for turning on the connection switch after the timing for turning on the interconnection switch. In the power converter device according to any one of claims 1 to 3 ,
It is provided between a DC power source that generates DC power and a power system through which three-phase AC power flows, and is composed of a grid-connected inverter device that includes an inverter circuit that performs DC-AC conversion between them. A power converter.

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