JP4370965B2 - Power converter - Google Patents

Description

  The present invention relates to a power converter that supplies a constant voltage to a load while suppressing voltage fluctuations of an AC power supply.

Conventionally, a number of power conversion devices for supplying a stable voltage from a power source to a load have been proposed. For example, as a general circuit system, a circuit having a so-called double converter configuration in which an AC power supply is once converted into DC and then converted into AC again is used (for example, see Patent Document 1).
As a circuit of such a double converter configuration, for example, a circuit system shown in FIG. 6 has been proposed (see, for example, Non-Patent Document 1).

  In this method, as shown in FIG. 6, the switching elements 10 and 11 are connected in parallel with the switching elements 10 and 11 by the PWM control of the switching elements 10 and 11 connected in series from the AC power source 1 via the reactor 40 and Energy is stored in the capacitors 31 and 32 connected in series, and the voltage Vdc of the capacitors 31 and 32 is controlled and converted so as to be DC, and then connected in parallel with the switching elements 10 and 11 and the capacitors 31 and 32. In addition, a stable arbitrary AC voltage is generated from the DC voltage of the smoothed capacitors 31 and 32 by the inverter circuit by PWM control of the switching elements 14 and 15 connected in series, and this is supplied to the load 6. It has become.

Note that the capacitor 33 in FIG. 6 is a filter capacitor. The reactor 41 and the capacitor 34 constitute an LC filter. Further, diodes 16 and 17, 20 and 21 are connected in antiparallel to the switching elements 10 and 11, 14 and 15, respectively.
On the other hand, for example, a circuit system shown in FIG. 7 has been proposed as a circuit system that compensates for power supply voltage fluctuations and supplies a stable voltage to a load (see, for example, Patent Document 2).

In this method, as shown in FIG. 7, if the voltage fluctuation of the AC power supply 1 occurs, the inverter circuit by PWM control of the switching elements 10 and 11 connected in series, a switching element 10及beauty 1 1 Parallel The AC voltage equivalent to the voltage fluctuation is output from the DC power source of the capacitors 31 and 32 connected in series to the AC power source 1 via the transformer 42 connected in series with the AC power source 1. Control is performed so that the sum of the voltages output via is constant. At this time, energy is stored in the capacitors 31 and 32 from the AC power supply 1 via the reactor 41 by the rectification operation by PWM control of the switching elements 14 and 15 connected in parallel with the capacitors 31 and 32 in series. However, the voltages of the capacitors 31 and 32 are controlled and converted so as to become direct current.

In FIG. 7, a capacitor 34 is a filter capacitor. In addition, the reactor 40 and the condenser 33 constitute an LC filter. Further, diodes 16 and 17, 20 and 21 are connected in antiparallel to the switching elements 10 and 11, 14 and 15, respectively.
Patent No. 3203464 JP-A-11-178216 JP-A-2-231965 OHM November 1999 issue "Power Electronics Guidebook" Ohm

  Here, as shown in FIG. 6, the operation principle of the circuit of the double converter configuration in which the AC power source is once converted to DC and then converted back to AC is as shown in FIG. Since the converter composed of the switching elements 10 and 11, the diodes 16 and 17 connected in antiparallel to the switching elements 10 and 11, and the capacitors 31 and 32 functions as a rectifier circuit, the rectifier circuit Can be regarded as a parallel current source 5 through which all energy required for the load 6 passes.

The converter composed of the switching elements 14 and 15 on the load 6 side, the diodes 20 and 21 connected in antiparallel to the switching elements 14 and 15, respectively, and the capacitors 31 and 32 operate as a so-called inverter circuit. Since a predetermined voltage is supplied to the load 6, it can be regarded as a parallel voltage source 3 through which all energy required by the load 6 passes. The capacitors 31 and 32 function as a common part of the rectifier circuit and the inverter circuit and as a power source.
As described above, in the double converter type circuit, all the energy for supplying the load 6 passes through the converter on either the AC power source 1 side or the load 6 side. It becomes a big thing, it becomes one factor which reduces conversion efficiency, and becomes a factor which increases running cost.

  On the other hand, the operation principle of the circuit system as shown in FIG. 7 is as shown in FIG. That is, in FIG. 9, the parallel current source 4 represents a rectifier circuit by PWM control of the switching elements 14 and 15 in FIG. 7, and the series voltage source 2 is an inverter circuit by PWM control of the switching elements 10 and 11 in FIG. Represents. At this time, when the series voltage source 2 generates an arbitrary voltage, a voltage obtained by adding the voltages of the two voltage sources of the AC voltage source 1 and the series voltage source 2 is applied to the load 6. . As a result, it can be seen that a constant voltage can be supplied to the load 6 by adding the voltage of the series voltage source 2 even when the voltage of the AC voltage source 1 is lowered. That is, it can be seen that each circuit configured in series and parallel is responsible for only energy for compensating for power supply fluctuations, and therefore has less loss than the double converter circuit shown in FIGS.

Further, in the conventional circuit system shown in FIGS. 6 and 7, both the rectifier circuit and the inverter circuit operate as a half bridge circuit, and therefore, it is necessary to select an applicable element having a high withstand voltage.
For example, when the AC power supply voltage is 200 [V], the voltage applied to both ends of the capacitors 31 and 32 is “√2 × 200 + √2 × 200 (note that √2 is the square root of 2). ”) And 565.7 [V]. Therefore, an element having a high withstand voltage of 1000 [V] is required, and the cost is increased due to lack of general versatility, and the element loss increases because the switching speed of the element becomes slower as the withstand voltage increases. Furthermore, since the converter circuit becomes high voltage, there is a problem that the circuit configuration becomes large.

In order to avoid this, for example, a converter circuit composed of a half bridge may be made into a full bridge. For example, as described in Patent Document 3, a double converter circuit is simplified. In addition, a method for making a full bridge has been proposed.
However, when the circuit as shown in FIG. 7 is simply made into a full bridge, both the inverter circuit and the rectifier circuit must have a full bridge configuration, and a transformer is required. The problem remains.
Therefore, the present invention has been made paying attention to the above-mentioned conventional unsolved problems, and suppresses running costs when applying a constant voltage to a load by suppressing voltage fluctuations of an AC voltage source and applying it. It aims at providing the power converter device which can reduce the proof pressure of an element.

In order to achieve the above object, a power generator according to claim 1 of the present invention is interposed between an AC power supply and a load, and applies a constant voltage to the load regardless of fluctuations in the power supply voltage of the AC power supply. In the power conversion apparatus to be supplied, the first arm and the second arm in which two switching elements each having a diode connected in anti-parallel are connected in series and the storage capacitor are connected in parallel. A first converter connected in series between the AC power supply and the load, and two switching elements connected in parallel to the second arm and connected in reverse parallel to the diode, respectively. and a third arm and the second arm and the energy storage capacitor that is, a second converter connected in parallel with said load to said load side of said first converter It includes data and, the, the first converter, said operated to compensate the variation of power supply voltage, and, the second converter, and is operated to perform the charge and discharge of the power storage capacitor It is characterized in that to operate so as to compensate for the energy consumption equivalent with the compensation operation of the first converter.

According to a second aspect of the present invention, there is provided a power converter that is interposed between an AC power supply and a load and supplies a constant voltage to the load regardless of fluctuations in the power supply voltage of the AC power supply. A first arm and a second arm in which two switching elements each having a diode connected in anti-parallel are connected in series, and a storage capacitor, and from the AC power source side, the first arm and the of the power storage capacitor and the second arm and the AC power supply first reactor is interposed between the and connected to be constructed and the alternating current power supply in parallel in this order first arm load a first converter connected in series between one end, said second arm and connected in parallel且Tsuda diodes respectively connected two switching elements in inverse parallel are connected in series It has three arms, said from the AC power supply side to the power storage for Konden'nsa and the second arm and the third arm is constituted by connecting in parallel in this order, said third arm is a second reactor A second converter connected to the other end of the load via a first filter capacitor , a first filter capacitor connected in parallel with the AC power source between the AC power source and the first reactor, and the load. A second filter capacitor connected in parallel with the load between the second reactor, the first converter is operated to compensate for fluctuations in the power supply voltage, and wherein the second converter, characterized in that to operate so as to compensate for the energy consumption equivalent with the compensation operation of the operation is allowed and the first converter so as to perform charging and discharging of the power storage capacitor It is.

  A power conversion device according to claim 3 is the power conversion device according to claim 1 or 2, wherein a cutoff means interposed between the AC power source and the first converter, and the first Switching means interposed between the converter and the load, and the switching means is configured to switch the load between the second converter, the cutoff means, and the first converter. It is characterized by being connected to.

A power conversion device according to a fourth aspect is the power conversion device according to any one of the first to third aspects, wherein the power storage device is connected in parallel to the power storage capacitor; And charging / discharging means for accommodating energy between the capacitor and the energy storage means.
Furthermore, the power converter device which concerns on Claim 5 is the power converter device in any one of the said Claims 1-4. The energy storage means connected in parallel with the said capacitor | condenser for electrical storage, The said alternating current It is characterized by comprising charging means connected in parallel with a power source for charging the energy storage means, and discharging means for charging the storage capacitor with the energy of the energy storage means.

  According to the power conversion device according to claim 1 and claim 2 of the present invention, the first and second converters are made into a full bridge, and the first converter is compensated for the voltage fluctuation of the AC power supply, In addition, since only the energy required for compensation for the voltage fluctuation is compensated by the second converter, the voltage fluctuation of the AC power supply is suppressed and the constant voltage is supplied to the load to increase the efficiency. Thus, the running cost can be suppressed and the withstand voltage of the applied element can be reduced.

  Moreover, according to the power converter device which concerns on Claim 3, the interruption | blocking means inserted between the said alternating current power supply and the said 1st converter, and the said 2nd converter, and the said load are inserted. Since the switching means is provided, the voltage supply to the load is continuously performed by operating the shut-off means or the switching means according to the abnormality occurrence state of the AC power supply voltage of the power conversion device or the AC power supply. Can do.

According to a fourth aspect of the present invention, there is provided an energy storage device connected in parallel with the storage capacitor, and energy is exchanged between the storage capacitor and the energy storage device by the charge / discharge device. Thus, the voltage supply to the load can be extended by an amount corresponding to the energy storage amount of the energy storage means.
Further, according to the power conversion device of the fifth aspect, the energy storage means connected in parallel with the power storage capacitor is provided, and the energy storage means is charged using the power supply voltage from the AC power supply. Since the power storage capacitor is charged by the energy of the energy storage means, the voltage supply to the load can be extended by an amount corresponding to the energy storage amount of the energy storage means.

Hereinafter, embodiments of the present invention will be described.
First, a first embodiment will be described.
FIG. 1 is a circuit diagram showing a configuration of a power converter according to the present invention. As shown in FIG. 1, switching elements 10 and 11, switching elements 12 and 13, and switching elements 14 and 15, each composed of, for example, a transistor, are connected in series to form arms A <b> 1 to A <b> 3. The arms A1 to A3 are connected in parallel, and a capacitor 30 is connected in parallel between the arm A1 composed of the switching elements 10 and 11 and the arm A2 composed of the switching elements 12 and 13. Further, diodes 16 to 21 are connected to the switching elements 10 to 15 in antiparallel.

A capacitor 33 as a filter capacitor is connected in parallel with the AC power source 1, and a capacitor 34 as a filter capacitor is connected in parallel with the load 6, and one terminal of the AC power source 1 and one terminal of the load 6 are connected. And are connected. The other terminal of the AC power supply 1 is connected to the series connection point of the switching elements 10 and 11 via the reactor 40, and the other terminal of the load 6 is connected to the series connection point of the switching elements 12 and 13. A series connection point of the switching elements 14 and 15 is connected to a connection point between the AC power source 1 and the load 6 via a reactor 41.
The switching elements 10 to 15 are PWM-controlled by a control circuit 90. The control circuit 90 performs PWM control according to the power supply voltage of the AC power supply 1.

In the configuration shown in FIG. 1, when the capacitor 30 is considered as a power source of a converter composed of an arm A1 composed of switching elements 10 and 11 and an arm A2 composed of switching elements 12 and 13, this converter is an AC power source. 1 and the load 6 are connected in series. Hereinafter, this converter is referred to as a serial converter X.
On the other hand, when the capacitor 30 is considered as an output of a converter composed of an arm A2 composed of switching elements 12 and 13 and an arm A3 composed of switching elements 14 and 15, this converter is connected in parallel to the AC power source 1. Will be connected. Hereinafter, this converter is referred to as a parallel converter Y.

FIG. 2 is a waveform diagram for explaining the operation of the series converter X of FIG. 1, and is an output voltage waveform of each arm when the N point on the emitter side of the switching element 11 of FIG. 1 is used as a reference.
The control circuit 90 monitors the power supply voltage of the AC power supply 1 and, when this power supply voltage is higher than a desired output voltage, causes the series converter X and the parallel converter Y to perform step-down operation.
Specifically, the switching elements 12 and 13 are controlled to be turned on in synchronization with the power supply voltage from the AC power supply 1. As a result, the output voltage waveform of the arm A2 composed of the switching elements 12 and 13 becomes a rectangular wave synchronized with the power supply voltage as shown in FIG.

  At this time, in order to step down the power supply voltage of the AC power supply 1, the switching elements 10 and 11 are synchronized with the power supply voltage when the output voltage waveform of the arm A1 composed of the switching elements 10 and 11 is shown in FIG. In addition, PWM control is performed so that the amplitude of the power supply voltage is reduced by a sine wave corresponding to the required step-down voltage.

  As a result, a sine wave having a small amplitude is output between the series connection points of the switching elements 10 and 11 of the arm A1 and the switching elements 12 and 13 of the arm A2 in the opposite phase to the power supply voltage. That is, it corresponds to a value obtained by subtracting the output voltage waveform of the arm A2 including the switching elements 12 and 13 illustrated in FIG. 2B from the output voltage waveform of the arm A1 including the switching elements 10 and 11 illustrated in FIG. It becomes a waveform. For this reason, a voltage corresponding to the required step-down voltage is subtracted from the power supply voltage, and as a result, the power supply voltage is stepped down.

  At this time, the switching elements 14 and 15 are operated as a parallel converter Y to charge and discharge the energy of the capacitor 30 consumed by the step-down operation while generating a counter voltage corresponding to the input voltage, and the voltage across the capacitor 30 is set to a predetermined direct current. The voltage Vdc is maintained. As a result, the parallel converter Y exchanges energy for compensation.

On the other hand, when the power supply voltage of the AC power supply 1 is lower than the desired output voltage, the series converter X and the parallel converter Y are boosted.
Specifically, as shown in FIG. 2A, the switching elements 10 and 11 are controlled to be turned on in synchronization with the power supply voltage from the AC power supply 1. As a result, the output waveform of the arm A1 including the switching elements 10 and 11 is a rectangular wave synchronized with the power supply voltage.

  At this time, as shown in FIG. 2 (b), the switching elements 12 and 13 are PWMed so as to output a compensation voltage in synchronization with the power supply voltage and to have a waveform reduced by a sine wave corresponding to the compensation voltage. Control. As a result, a sine wave having the same phase as the power supply voltage and a small amplitude is output between the series connection points of the switching elements 10 and 11 of the arm A1 and the switching elements 12 and 13 of the arm A2. For this reason, the compensation voltage in the power supply voltage is added, and the power supply voltage is boosted.

At this time, the switching elements 14 and 15 are operated as a parallel converter Y, and while generating a counter voltage corresponding to the output voltage, the energy of the capacitor 30 consumed by the boosting operation is charged and discharged. Is maintained at a predetermined DC voltage Vdc.
By doing so, the energy supplied to the load 6 passes only through the series converter X, and only the energy used for voltage compensation passes through the parallel converter Y. Therefore, compared with the conventional double converter system. Thus, the loss of the parallel converter Y can be reduced, and high efficiency can be achieved.

Further, by changing the PWM operation of the switching elements 10 to 15 according to the state of the power supply voltage of the AC power supply 1, both the step-up operation and the step-down operation can be realized without using a transformer.
In addition, since each of the series converter X and the parallel converter Y is configured by a full bridge circuit, the withstand voltage of each switching element can be reduced as compared with the case where the series converter X and the parallel converter Y are configured by a half bridge circuit. Can be reduced.

  Here, in the first embodiment, the arm A1 corresponds to the first arm, the arm A2 corresponds to the second arm, the arm A3 corresponds to the third arm, and the capacitor 30 is for power storage. Corresponding to the capacitor, the serial converter X corresponds to the first converter, the parallel converter Y corresponds to the second converter, the reactor 40 corresponds to the first reactor, and the reactor 41 corresponds to the second reactor. , Capacitors 33 and 34 correspond to the first and second filter capacitors, respectively.

Next, a second embodiment of the present invention will be described.
In the second embodiment, a blocking circuit 51 (blocking means) for blocking the connection between the AC power supply 1 and the reactor 40 is added to the AC power supply 1 side in the first embodiment, Further, a changeover switch 50 (switching means) is added to the load 6 side. The changeover switch 50 has movable contacts 50a and 50b. The movable contact 50a is connected to a series connection point of the switching elements 12 and 13 and a connection point of the capacitor 34. The movable contact 50b is connected to the breaking circuit. 51 and the reactor 40, and the fixed contact 50 c is connected to one terminal of the load 6.

  The changeover switch 50 and the cutoff circuit 51 are driven by the control circuit 90a. Similar to the control circuit 90 in the first embodiment, the control circuit 90a controls driving of the switching elements 10 to 15 in accordance with the power supply voltage, and controls the changeover switch 50 and the cutoff circuit 51, thereby providing power. When each part of the converter 100 is operating normally, the changeover switch 50 is controlled so that the fixed contact 50c and the movable contact 50a are in a conductive state, and the interruption circuit 51 is in a conductive state. By controlling, a circuit equivalent to the first embodiment is configured.

  On the other hand, when an abnormality occurs in the power conversion device 100, for example, when a switching element or a diode breaks down, the changeover switch 50 is controlled to be in a conductive state between the fixed setting 50c and the movable contact 50b. As a result, the AC power supply 1 and the load 6 are directly connected, and voltage supply to the load 6 can be secured. Further, when a load short circuit or the like occurs and the load 6 and the power conversion device 100 or the load 6 and the AC power supply 1 are to be disconnected, the changeover switch 50 is controlled to be in an open state. As a result, the load 6 is disconnected from the power converter 100 and the AC power supply 1, and the load 6 is adversely affected by an abnormality of the power converter 100 or the AC power supply 1. Can be avoided.

In addition, when the power supply voltage of the AC power supply 1 decreases beyond the compensation range, the cutoff circuit 51 is controlled to be in the cutoff state. In this state, voltage supply to the load 6 can be continued by operating the parallel converter Y as an inverter using the capacitor 30 as a power source.
In this way, the AC power source 1 is provided with the cutoff circuit 51 for separating the AC power source 1 and the power converter 100, and the load 6 and the AC power source 1 are directly connected to the load 6 side. Alternatively, since the changeover switch 50 for disconnecting the load 6 and the power conversion device 100 is provided, even if an abnormality of the power conversion device 100, an abnormality of the AC power source 1 or the like occurs, depending on the situation By controlling the changeover switch 50 and the cutoff circuit 51, the voltage supply to the load 6 can be continued, and the trouble of the load 6 due to the abnormality of the power converter 100 or the AC power supply 1 is avoided. be able to.

  In the second embodiment, there is provided a case in which both a cutoff circuit 51 for disconnecting the AC power source 1 from the power converter 100 and a changeover switch 50 for directly connecting the load 6 to the AC power source 1 are provided. Although described, it is not always necessary to provide both the cutoff circuit 51 and the changeover switch 50. However, by providing both, it becomes possible to cope with both the abnormality on the AC power supply 1 side or the abnormality of the power conversion device 100, and the voltage supply to the load 6 can be continued in more scenes. The reliability of the conversion device 100 can be improved.

Next, a third embodiment of the present invention will be described.
In the third embodiment, an energy storage element 60 (energy storage means) is connected in parallel with the capacitor 30 via the charge / discharge means 61 in the second embodiment. As the energy storage element 60, for example, a secondary battery such as a battery, a flywheel, or the like can be applied. As the charge / discharge means 61, for example, a current reversible chopper circuit (two-quadrant chopper circuit) or the like can be applied.

When the power conversion apparatus 100 is normal and the power supply voltage from the AC power supply 1 is within the compensation voltage range that can be compensated by the power conversion apparatus 100, the operation is the same as in the second embodiment. The parallel converter Y charges and discharges energy to and from the capacitor 30.
At this time, the charging / discharging means 61 charges the energy storage element 60 from the capacitor 30 with energy.
From this state, when an abnormality occurs in the AC power supply 1 and, for example, a power failure occurs, the control circuit 90a switches the cutoff circuit 51 to the cutoff state and disconnects the AC power supply 1 from the power converter 100. Then, by using the capacitor 30 as a power source, an AC voltage is generated by the parallel converter Y and supplied to the load 6, so that the voltage supply to the load 6 is continued.

At this time, the charging / discharging means 61 starts charging the capacitor 30 using the energy storage element 60 as an energy source when the control circuit 90a detects that the power supply using the capacitor 30 as a power source is started.
In this way, the voltage supply to the load 6 can be continued by the capacitor 30 and not only the energy equivalent to the energy stored in the capacitor 30 but also the energy equivalent to the energy stored in the energy storage element 60. The voltage supply to the load 6 can be continued, and the voltage supply time to the load 6 can be extended.

Next, a fourth embodiment of the present invention will be described.
In the fourth embodiment, in the third embodiment, a discharge unit 63 is provided instead of the charge / discharge unit 61, and the energy storage element 60 ( The charging means 62 for charging the energy storage means) is provided. As the charging means 62, for example, an AC-DC conversion circuit such as a diode rectification circuit or a PWM rectification circuit can be applied. As the discharging means 63, for example, a DC-DC conversion such as a boost chopper circuit or a flyback converter. A circuit can be applied.

  That is, also in the fourth embodiment, as in the second embodiment, when the AC power supply 1 is within the compensation voltage range, or when the power conversion device 100 is normal, a predetermined value is used. A voltage is supplied to the load 6 and the capacitor 30 is charged and discharged by the parallel converter Y. At this time, the charging means 62 charges the energy storage element 60 using the AC voltage from the AC power supply 1 as energy.

From this state, when an abnormality occurs in the AC power supply 1 and, for example, a power failure occurs, the control circuit 90a switches the cutoff circuit 51 to the cutoff state and disconnects the AC power supply 1 from the power converter 100. Then, by using the capacitor 30 as a power source, an AC voltage is generated by the parallel converter Y and supplied to the load 6, so that the voltage supply to the load 6 is continued.
At this time, the charging unit 62 finishes charging the energy storage element 60, and when the discharging unit 63 detects that the power supply using the capacitor 30 as a power source is started by the control circuit 90a, the energy storage element 60 is detected. Is used as an energy source to start charging the capacitor 30.

  In this case, as in the third embodiment, the predetermined voltage of the load 6 can be supplied while using the series converter X and the parallel converter Y, and at the time of a power failure, etc. Thus, the voltage supply to the load 6 can be continued by the capacitor 30, and at this time, not only the energy equivalent amount stored in the capacitor 30 but also the energy equivalent amount stored in the energy storage element 60. The voltage supply to the load 6 can also be continued, and the voltage supply time to the load 6 can be extended.

It is an example of the circuit diagram of the power converter device showing the 1st Embodiment of this invention. It is a wave form diagram with which it uses for operation | movement description of 1st Embodiment. It is an example of the circuit diagram of the power converter device showing 2nd Embodiment. It is an example of the circuit diagram of the power converter device showing 3rd Embodiment. It is an example of the circuit diagram of the power converter device showing 4th Embodiment. It is a circuit diagram which shows an example of the conventional power converter device. It is a circuit diagram which shows the other example of the conventional power converter device. It is explanatory drawing for demonstrating the principle of operation of the power converter device of FIG. It is explanatory drawing for demonstrating the principle of operation of the power converter device of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 6 Load 10-15 Switching element 16-21 Diode 30 Capacitor 33, 34 Filter capacitor 50 Changeover switch 51 Cutoff circuit 60 Energy storage element (energy storage means)
61 Charging / discharging means 62 Charging means 63 Discharging means 90, 90a Control circuits A1 to A3 Arm X Series converter (first converter)
Y Parallel converter (second converter)

Claims (5)

In a power conversion device that is inserted between an AC power supply and a load, and supplies a constant voltage to the load regardless of fluctuations in the power supply voltage of the AC power supply.
A first arm and a second arm connected in series with two switching elements each having a diode connected in anti-parallel, and a storage capacitor connected in parallel, and between the AC power supply and the load A first converter connected in series with
Two switching elements connected in parallel with the second arm and diodes connected in anti-parallel, respectively, are composed of a third arm connected in series, the second arm, and the storage capacitor. A second converter connected in parallel with the load on the load side of the first converter ,
The first converter is operated so as to compensate the fluctuation of the power supply voltage, and the second converter is operated so as to charge / discharge the storage capacitor, and the first converter A power conversion device that is operated so as to compensate for an amount corresponding to energy consumption accompanying the compensation operation. In a power conversion device that is inserted between an AC power supply and a load, and supplies a constant voltage to the load regardless of fluctuations in the power supply voltage of the AC power supply.
Two switching elements, each of which is connected in antiparallel with a diode, have a first arm and a second arm connected in series, and a storage capacitor, and the first arm and the power storage from the AC power supply side. one end of the first reactor is interposed in the AC power supply and the load between the use capacitor and said second arm is constituted by connecting in parallel in this order and said AC power supply and the first arm A first converter connected in series between
A third arm and the second arm and is connected in parallel且Tsuda diode connected in antiparallel have been two switching elements connected in series, and said power storage for Konden'nsa from the AC power supply side A second converter in which the second arm and the third arm are connected in parallel in this order, and the third arm is connected to the other end of the load via a second reactor; ,
A first filter capacitor connected in parallel with the AC power source between the AC power source and the first reactor ;
A second filter capacitor connected in parallel with the load between the load and the second reactor;
The first converter is operated so as to compensate the fluctuation of the power supply voltage, and the second converter is operated so as to charge / discharge the storage capacitor, and the first converter A power conversion device that is operated so as to compensate for an amount corresponding to energy consumption accompanying the compensation operation. Shut-off means interposed between the AC power source and the first converter;
Switching means interposed between the second converter and the load,
3. The switching means is configured to connect the load to any one of the second converter and between the cutoff means and the first converter. The power converter described. Energy storage means connected in parallel with the storage capacitor;
The power converter according to any one of claims 1 to 3, further comprising charge / discharge means for accommodating energy between the storage capacitor and the energy storage means. Energy storage means connected in parallel with the storage capacitor;
Charging means connected in parallel with the AC power source to charge the energy storage means;
5. The power conversion device according to claim 1, further comprising: a discharging unit that charges the power storage capacitor with the energy of the energy storage unit.

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