JP3967706B2 - Power converter - Google Patents

Description

  The present invention relates to a power converter capable of combining a plurality of inverters and obtaining a desired output waveform by gradation control.

Power converters that combine multiple inverters and output by gradation control, for example, voltage fluctuations that compensate for voltage drops by monitoring voltage fluctuations such as instantaneous voltage drops (hereinafter referred to as instantaneous drops) in the power system. Used in compensation devices.
A conventional voltage fluctuation compensator is configured by a plurality of voltage compensation circuits that are connected in series to a power system and output a compensation voltage with either positive or negative polarity. Each voltage compensation circuit is provided with a full bridge inverter composed of four semiconductor switching elements with diodes connected in antiparallel, and a charging capacitor, which converts the DC voltage of the charging capacitor into AC and outputs it. In addition, a high-speed mechanical steady short-circuit switch is provided in parallel at the output terminal of each voltage compensation circuit. The charging capacitors in each voltage compensation circuit are charged with different voltages by a charging diode and a charging transformer (see, for example, Patent Document 1).

JP 2002-359928 A

  In such a conventional power converter, the AC sides of a plurality of independent single-phase inverters are connected in series, and each charging capacitor on the DC input side of each single-phase inverter is charged with a different voltage. The Each charging capacitor is charged with a voltage by a charging diode, a charging resistor, and a secondary winding of the charging transformer provided independently, and the primary winding of the charging transformer is connected to the power system. In this way, the plurality of energy storage means (charging capacitors) that are input to each single-phase inverter are each provided with a charging circuit independently, and the number of charging circuits increases as the series number of single-phase inverters increases. In addition, there is a problem that a large capacity charging transformer is required.

  The present invention was made to solve the above-described problems, and is a power conversion device in which the AC sides of a plurality of single-phase inverters are connected in series and multiplexed, and the input of each single-phase inverter The charging circuit for charging a plurality of energy storage means is prevented from increasing in size as the number of single inverters connected in series is increased, and the circuit required for charging is simplified and the device configuration is reduced. It aims at miniaturization and simplification.

The power conversion device according to the present invention includes:
A power converter that outputs AC power to a connected load,
A plurality of single-phase inverters connected in series on the AC side ;
A plurality of energy storage means respectively connected to the DC side of the plurality of single-phase inverters ;
A charging circuit for outputting DC power to the energy storage means;
A control circuit for controlling the plurality of single-phase inverters and controlling the power output to the load at a predetermined AC voltage ;
The plurality of single-phase inverters can output the electric power stored in the energy storage means connected to the AC side based on the control of the control circuit,
The charging voltage of the plurality of energy storage means is set for each energy storage means,
One end of the charging circuit is connected to a first energy storage unit among the plurality of energy storage units,
The other end of the charging circuit is connected to a line parallel to the plurality of single-phase inverters ,
The control circuit, when storing power in a plurality of energy storage means other than the first energy storage means, a plurality of energy storage means to be subjected to a storage operation among the plurality of other energy storage means. Is connected in series with the charging circuit, and the energy storage means farthest from one end of the charging circuit among the plurality of energy storage means to be stored is connected to the line. A plurality of single-phase inverters and the charging circuit are controlled.

  In such a power converter, each energy storage means of each single-phase inverter in the single-phase multiple converter can be charged using a charging circuit connected to one single-phase inverter in the single-phase multiple converter. Regardless of the number of single inverters connected in series, the charging circuit can be reduced in size and simplified, and the device configuration can be reduced in size and simplified.

Embodiment 1 FIG.
Hereinafter, a power converter according to Embodiment 1 of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram in which a power conversion device according to Embodiment 1 of the present invention is applied to a voltage fluctuation compensation device. As shown in FIG. 1, a single-phase multiple converter 110 is configured by connecting the AC sides of a plurality (in this case, three) of single-phase inverters 11, 12, and 13 in series. Each of the single-phase inverters 11 to 13 is composed of a full-bridge inverter including four MOS transistors 9sw11 to 9sw14, 9sw21 to 9sw24, and 9sw31 to 9sw34 having diodes connected in antiparallel, and a charging capacitor 10 as an energy storage unit. (10pn1 to 10pn3) are provided to constitute each voltage compensation unit 15.

The single-phase multiple converter 110 is connected in series to an AC power supply such as a power system, and the charging voltages V1 to V3 of the charging capacitor 10 are ON / OFF of the MOS transistors 9 (9sw11 to 9sw14, 9sw21 to 9sw24, 9sw31 to 9sw34). It is output from each single-phase inverter 11-13 with either positive or negative polarity by the off control and is connected to the AC power supply.
In addition, a mechanical steady short-circuit switch 8 is provided in parallel at the output end of the single-phase multiple converter 110, and electric power is supplied to the load side through the steady short-circuit switch 8 in normal times. The single-phase inverters 11 to 13 may be constituted by self-extinguishing semiconductor switching elements other than the MOS transistor 9.

Among the single-phase inverters 11 to 13, the single-phase inverter 13 that receives the charging capacitor 10 pn 3 having the largest capacitor voltage is connected to a switching regulator 120 as a DC / DC converter for charging each charging capacitor 10. . The ratio of the voltage charged in each charging capacitor 10 is set to a power ratio of about 2. That is, the following relationship is satisfied.
V3 = 2 × V2 = 2 × 2 × V1
The details of the charging method will be described later.

The steady short-circuit switch 8 and each MOS transistor 9 are connected to the control circuit 30 and operated by command signals z, g11 to g14, g21 to g24, and g31 to g34 from the control circuit 30. The configuration and operation of the control circuit 30 will be described below with reference to FIG.
When the AC voltage V from the AC power source is input to the control circuit 30 and an instantaneous voltage drop (hereinafter abbreviated as “instantaneous voltage drop”) occurs, the instantaneous voltage drop detection unit 37 detects the instantaneous voltage drop, and the signal z indicates the single-phase multiple converter 110. The steady short-circuit switch 8 is turned off. Then, the compensation voltage calculation unit 33 calculates the compensation voltage Via based on the AC voltage V and the set voltage 31 so as to compensate for the voltage fluctuation of the AC voltage V. At this time, the set voltage 31 is a normal voltage.

  When the compensation voltage Via is calculated, as shown in FIG. 2, the signal is amplified by the amplifier circuit 35, further subjected to absolute value conversion, and then converted into a 3-bit digital signal (D1 to D3) by the A / D converter 36. Convert to When the magnitude of the compensation voltage Via becomes equal to the charging voltage V1 of the charging capacitor 10pn1, only the least significant bit D1 in the output signal from the A / D converter 36 becomes 1, that is, “001”. In the case of “010” to “111”, the gain of the amplifier circuit 35 is adjusted in advance so as to be equal to the combination of the charging voltages of the charging capacitor 10.

On the other hand, the calculated compensation voltage Via is also input to the polarity determination circuit 38 to determine the polarity. Thereafter, the drive signal generator 39 selects an active signal among the digital signals D1 to D3 depending on whether the polarity of the compensation voltage Via is positive or negative, and the drive signal to the single-phase multiple converter 110 is selected. g11 to g14, g21 to g24, and g31 to g34 are generated, respectively.
For example, in the voltage fluctuation compensation device shown in FIG. 1, when the least significant bit D1 = 1, when the voltage polarity is positive, the MOS transistors 9sw11 and 9sw14 are turned on and the MOS transistors 9sw12 and 9sw13 are turned off. The charging voltage V1 is output with a positive polarity. When the voltage polarity is negative, the MOS transistors 9sw12 and 9sw13 are turned on and the MOS transistors 9sw11 and 9sw14 are turned off, so that the charging voltage V1 is output with a negative polarity. When D1 = 0, one of the upper arm side 9sw12 and 9sw14 or the lower arm side 9sw11 and 9sw13 of the MOS transistors 9sw11 to 9sw14 is turned on, the other is turned off, and the output terminal is short-circuited. 11 output is set to almost zero.

  As shown in FIG. 3, the outputs G1 to G3 of the single-phase inverters 11 to 13 are combined, and the single-phase multiple converter 110 may generate voltage outputs of eight gradations “000” to “111”. The maximum compensation voltage is V1 + V2 + V3. Here, for example, in the case of voltage output in all 8 gradations, a simulated AC voltage can be generated by combining the outputs G1 to G3 of the single-phase inverters 11 to 13 as shown in FIG.

Next, a method for charging each charging capacitor 10 will be described below.
As described above, of the single-phase inverters 11 to 13, the single-phase inverter 13 that receives the charging capacitor 10 pn 3 having the largest capacitor voltage is connected to the switching regulator 120 for charging each charging capacitor 10.
As shown in FIG. 1, the switching regulator 120 includes a half-wave rectifier circuit including a diode 41, a charge limiting resistor 42, and a smoothing capacitor 43, a reactor 44, a MOS transistor 45 in which a diode is connected in antiparallel, and a charge. And a chopper circuit composed of a diode 46 for the circuit. The cathode side of the charging diode 46 is connected to the plus side of the charging capacitor 10pn3 that is the DC input of the single-phase inverter 13, and supplies charging power. Note that a semiconductor switching element other than the MOS transistor 45 may be used for the switch of the chopper circuit.

Next, the detailed operation of charging will be described below with reference to FIGS. 4 to 7 showing the flow of current during each operation.
First, the AC power supply is DC smoothed by the half-wave rectifier circuits 41 to 43, the MOS transistor 45 is turned on, and a current is passed from the smoothing capacitor 43 to the reactor 44 as shown in FIG. Thereby, energy is accumulated in the reactor 44.
Thereafter, when the MOS transistor 45 is turned off, the current flowing out of the smoothing capacitor 43 becomes zero. Here, when all the MOS transistors 9 (9sw11 to 9sw14, 9sw21 to 9sw24, 9sw31 to 9sw34) of the single-phase inverters 11 to 13 are turned off, the reactor 44 works to keep the current flowing. As shown, the energy stored in the reactor 44 supplies power to the charging capacitor 10pn3 through the charging diode 46, and a charging current flows through the antiparallel diode of the MOS transistor 9sw34 of the single-phase inverter 13. Thereby, charging capacitor 10pn3 is charged.

  Next, when the voltage V3 of the charging capacitor 10pn3 is charged to a predetermined value, the MOS transistor 9sw31 of the single-phase inverter 13 is turned on. As a result, as shown in FIG. 6, the charging current passes from the charging diode 46 through the MOS transistor 9sw31 of the single-phase inverter 13, through the single-phase inverters 12 and 11, the charging capacitors 10pn2 and 10pn1, and the steady short circuit switch 8. The charging capacitors 10pn2 and 10pn1 are charged through a closed loop returning to the reactor 44. Details of the charging current path at this time are as follows: MOS transistor 9sw31 of single-phase inverter 13 to anti-parallel diode of MOS transistor 9sw23 of single-phase inverter 12 to charging capacitor 10pn2 to anti-parallel diode of MOS transistor 9sw22 to single-phase inverter 11 The reverse parallel diode of the MOS transistor 9sw13 to the charging capacitor 10pn1 to the reverse parallel diode of the MOS transistor 9sw12 to the steady short-circuit switch 8 to the reactor 44. Note that the steady short-circuit switch 8 is closed when the charging capacitor 10 is charged.

At this time, since the two charging capacitors 10pn1 and 10pn2 are charged in series, the ratio of the charged voltages V1 and V2 is determined by the capacitance ratio of the charging capacitors 10pn1 and 10pn2. Therefore, when the predetermined voltage ratio between V1 and V2 and the capacitance ratio between the charging capacitor 10pn1 and the charging capacitor 10pn2 are different, the charging time until the predetermined voltage is different.
When the voltage V1 of the charging capacitor 10pn1 is charged to a predetermined voltage first, the MOS transistor 9sw11 of the single-phase inverter 11 is turned on. As a result, the charging current flowing through the path shown in FIG. 6 flows through the MOS transistor 9sw11 in the single-phase inverter 11 as shown in FIG. 7, and the charging capacitor 10pn1 is out of the charging current path and is not charged. Therefore, only the charging capacitor 10pn2 that is the DC input of the single-phase inverter 12 is charged.

Thereafter, when the voltage V2 of the charging capacitor 10pn2 is also charged to a predetermined voltage, the on / off operation of the MOS transistor 45 is stopped and the charging operation is terminated. The rise of the capacitor voltage in the above charging method is as shown in FIG.
When the voltage V2 of the charging capacitor 10pn2 is charged up to a predetermined voltage before the voltage V1 of the charging capacitor 10pn1, the MOS transistor 9sw21 of the single-phase inverter 12 is turned on so that the charging capacitor 10pn2 is removed from the charging current path. After that, only the charging capacitor 10pn1 is charged.

  As described above, the MOS transistor 45 of the switching regulator 120 is turned on, energy is stored in the reactor 44, the MOS transistor 45 is turned off, and the charging current is supplied from the reactor 44 to charge each charging capacitor 10. This is repeated by turning on and off the MOS transistor 45. At this time, the MOS transistor 45 controls the on / off DUTY by PWM control, and when all the voltages V1, V2, and V3 of the respective charging capacitors 10 become predetermined voltages, the charging ends by stopping the off-off operation.

  As described above, the switching regulator 120 is connected to the single-phase inverter 13, and the operation of the switching regulator 120 causes the charging capacitors 10pn1 to be DC inputs of all the single-phase inverters 11 to 13 in the single-phase multiple converter 110. 10pn3 is charged. Thus, since all the charging capacitors 10pn1 to 10pn3 can be charged by one charging circuit (switching regulator 120), even if the number of single inverters connected in series increases, the number of charging circuits may be one, The circuit required for this can be simplified, and the apparatus configuration can be reduced in size and simplified.

In addition, since charging is performed by the switching regulator 120, the effective value of the charging power can be increased as compared with the conventional case where a transformer is used, so that charging can be performed at high speed.
Furthermore, since switching regulator 120 is connected to single-phase inverter 13 having charging capacitor 10pn3 having the highest capacitor voltage as input, each charging capacitor 10 can be reliably charged to a predetermined voltage. Further, when the voltage of the charging capacitor 10 becomes a predetermined voltage, the predetermined MOS transistor 9 of the corresponding single-phase inverter 11 to 13 is turned off, and the charging capacitor 10 is removed from the path of the charging current. The battery can be charged to a desired voltage with high reliability.
Furthermore, since the on / off DUTY of the MOS transistor 45 in the switching regulator 120 is changed using PWM control, the effective charging current value can be increased by highly reliable control, and the charging time can be shortened.

Further, in this embodiment, the AC power source of the main circuit of the voltage fluctuation compensator is used, and the DC input obtained by rectifying the AC is used as the input of the chopper circuits 44 to 46 in the switching regulator 120 constituting the charging circuit. For this reason, the charging circuit of the voltage fluctuation compensator can be easily and simply configured. However, the DC input of the chopper circuits 44 to 46 may be configured independently of the power supply of the main circuit. The arrangement position of the single-phase inverter 13 to which the charging circuit configured is connected is not limited to the end on the AC power supply side, and may be any position in the single-phase multiple converter 110. Moreover, although the switching regulator 120 of the charging circuit has been described with the configuration of the chopper circuit, it may have a configuration other than the chopper circuit, such as a flyback converter.
Further, the case where the present invention is applied to a voltage fluctuation compensation device has been described, but the present invention is not limited to this, and a single-phase multiple converter is configured by connecting AC sides of a plurality of single-phase inverters having energy storage means in series. Any device using a power converter for gradation control can be applied.

Embodiment 2. FIG.
In the first embodiment, when charging of each charging capacitor 10 is started, the MOS transistors 9 (9sw11 to 9sw14, 9sw21 to 9sw24, 9sw31 to 9sw34) of the single-phase inverters 11 to 13 are all turned off, and the single-phase inverter 13 is turned off. After the voltage V3 of the charging capacitor 10pn3 reached the predetermined value, the MOS transistor 9sw31 of the single-phase inverter 13 was turned on to charge the charging capacitors 10pn1 and 10pn2.
In the second embodiment, a case where charging capacitors 10pn1 to 10pn3 are charged simultaneously from the start of charging will be described. The circuit configuration of the voltage fluctuation compensator including the switching regulator 120 is the same as that in the first embodiment.

  As shown in FIG. 9, only the MOS transistor 9sw31 of the single-phase inverter 13 is turned on from the start of charging. As a result, the charging current flowing from the reactor 44 in which energy is stored branches into two, one of which returns from the charging diode 46 to the charging capacitor 10pn3 of the single-phase inverter 13 to the reverse parallel diode to the reactor 44 of the MOS transistor 9sw34, Charging capacitor 10pn3 is charged. The other is from the charging diode 46 to the MOS transistor 9sw31 of the single-phase inverter 13 to the reverse-parallel diode of the MOS transistor 9sw23 of the single-phase inverter 12 to the charging capacitor 10pn2 to the reverse-parallel diode of the MOS transistor 9sw22 to the MOS transistor of the single-phase inverter 11. Returning from the reverse parallel diode of 9sw13 to the charging capacitor 10pn1 to the reverse parallel diode of the MOS transistor 9sw12 to the steady short circuit switch 8 to the reactor 44, the charging capacitors 10pn2 and 10pn1 are charged.

That is, charging is performed in parallel with charging capacitor 10pn3 and charging capacitors 10pn2, 10pn1.
FIG. 10 is a diagram showing a voltage increase of each charging capacitor 10 in this embodiment. In this case, as shown in FIG. 10, the voltage increases from the start of charging while maintaining the relationship of V3 = V1 + V2, and one of them reaches a predetermined value.
Here, a case where the voltage V1 first reaches a predetermined value will be described as an example. When the voltage V1 of the charging capacitor 10pn1 is charged to a predetermined voltage first, the MOS transistor 9sw11 of the single-phase inverter 11 is turned on. As a result, the charging current flowing through the path shown in FIG. 9 flows through the MOS transistor 9sw11 in the single-phase inverter 11 as shown in FIG. 11, and the charging capacitor 10pn1 is out of the charging current path and is not charged. Therefore, the charging is changed to parallel charging of the charging capacitor 10pn3 and the charging capacitor 10pn2.

At this time, since V3> V2, only the charging capacitor 10pn2 is charged until V3 = V2. After V3 = V2, while maintaining this relationship, charging is performed through the charging current path shown in FIG. 11 until V2 reaches a predetermined voltage.
After V2 reaches a predetermined voltage, all the MOS transistors 9 are turned off, so that the state shown in FIG. 5 shown in the first embodiment is obtained and only the charging capacitor 10pn3 is charged.
When the voltages V1, V2, and V3 of the respective charging capacitors 10 all become predetermined voltages, the charging is terminated by stopping the on / off operation of the MOS transistor 45 of the chopper circuit.

  Also in this embodiment, all charging capacitors 10pn1 to 10pn3 can be charged by one charging circuit (switching regulator 120), and the same effect as in the first embodiment can be obtained.

Embodiment 3 FIG.
In the first and second embodiments, the cathode side of the charging diode 46 is connected to the plus side of the charging capacitor 10pn3 that is the DC input of the single-phase converter 13. In this embodiment, as shown in FIG. 12, the polarities of the diode 41a and the smoothing capacitor 43a of the half-wave rectifier circuit constituting the switching regulator 120a are reversed from those of the first embodiment, and similarly, the chopper circuit The polarities of the charging diode 46a and the MOS transistor 45a were reversed, and the anode side of the charging diode 46a was connected to the negative side of the charging capacitor 10pn3.

Even with such a circuit configuration, each charging capacitor 10 can be charged, which will be described below.
First, the AC power supply is DC smoothed by the half-wave rectifier circuits 41a, 42, and 43a, the MOS transistor 45a is turned on, and a current is passed from the smoothing capacitor 43a to the reactor 44 as shown in FIG. Thereby, energy is accumulated in the reactor 44.
Thereafter, when the MOS transistor 45a is turned off, the current flowing out of the smoothing capacitor 43a becomes zero. Here, when all the MOS transistors 9 (9sw11 to 9sw14, 9sw21 to 9sw24, 9sw31 to 9sw34) of the single-phase inverters 11 to 13 are turned off, the reactor 44 works to keep the current flowing. As shown, the energy accumulated in the reactor 44 supplies power to the charging capacitor 10pn3 through the antiparallel diode of the MOS transistor 9sw33 of the single-phase inverter 13, and a charging current flows through the charging diode 46a. Thereby, charging capacitor 10pn3 is charged.

  Next, when the voltage V3 of the charging capacitor 10pn3 is charged to a predetermined value, the MOS transistor 9sw32 of the single-phase inverter 13 is turned on. As a result, as shown in FIG. 15, the charging current is changed from the reactor 44 to the steady short-circuit switch 8 to the reverse parallel diode of the MOS transistor 9sw11 of the single phase inverter 11 to the reverse parallel diode of the charging capacitor 10pn1 to MOS transistor 9sw14 to the single phase inverter 12. The reverse parallel diode of the MOS transistor 9sw21 to the charging capacitor 10pn2, the reverse parallel diode of the MOS transistor 9sw24, the MOS transistor 9sw32 of the single-phase inverter 13, the charging diode 46a to the reactor 44, and the charging capacitors 10pn2 and 10pn1 are charged. The Note that the steady short-circuit switch 8 is closed when the charging capacitor 10 is charged.

At this time, since the two charging capacitors 10pn1 and 10pn2 are charged in series, the ratio of the charged voltages V1 and V2 is determined by the capacitance ratio of the charging capacitors 10pn1 and 10pn2.
When voltage V1 of charging capacitor 10pn1 is charged to a predetermined voltage first, MOS transistor 9sw13 of single-phase inverter 11 is turned on. As a result, the charging current flowing in the path shown in FIG. 15 flows through the MOS transistor 9sw13 in the single-phase inverter 11 as shown in FIG. 16, and the charging capacitor 10pn1 is out of the charging current path and is not charged. Therefore, only the charging capacitor 10pn2 that is the DC input of the single-phase inverter 12 is charged.

  Thereafter, when the voltage V2 of the charging capacitor 10pn2 is also charged to a predetermined voltage, the on / off operation of the MOS transistor 45a is stopped and the charging operation is terminated. The rise of each capacitor voltage in the above charging method is the same as that in FIG. 8 shown in the first embodiment.

  As in the second embodiment, the charging capacitors 10pn1 to 10pn3 can be charged simultaneously from the start of charging. In this case, by turning on only the MOS transistor 9sw32 of the single-phase inverter 13 from the start of charging. Charging is possible, and the rise of each capacitor voltage is the same as in FIG. 10 described in the second embodiment.

Embodiment 4 FIG.
In the first to third embodiments, the on / off DUTY of the MOS transistors 45 and 45a in the switching regulators 120 and 120a is changed so that the charging current is constant. However, the on / off DUTY of the MOS transistors 45 and 45a is constant. However, since adjustment of the charging voltage of each charging capacitor 10 is performed by the MOS transistors 9 (9sw11 to 9sw14, 9sw21 to 9sw24, 9sw31 to 9sw34) of the single-phase inverters 11 to 13, each charging capacitor 10 has a desired voltage. Can be charged.
In this case, since the ON / OFF DUTY of the MOS transistors 45 and 45a may be fixed, control by the PWM control or the like is not necessary, and the control of the switching regulators 120 and 120a can be simplified.

It is the schematic block diagram which showed the power converter device by Embodiment 1 of this invention about the voltage fluctuation compensation apparatus. It is a block diagram which shows the control circuit by Embodiment 1 of this invention. It is a figure explaining operation | movement of the power converter device by Embodiment 1 of this invention. It is a figure explaining the charging operation by Embodiment 1 of this invention. It is a figure explaining the charging operation by Embodiment 1 of this invention. It is a figure explaining the charging operation by Embodiment 1 of this invention. It is a figure explaining the charging operation by Embodiment 1 of this invention. It is a figure which shows the change of the charging voltage by Embodiment 1 of this invention. It is a figure explaining the charging operation by Embodiment 2 of this invention. It is a figure which shows the change of the charging voltage by Embodiment 2 of this invention. It is a figure explaining the charging operation by Embodiment 2 of this invention. It is the schematic block diagram which showed the power converter device by Embodiment 3 of this invention about the voltage fluctuation compensation apparatus. It is a figure explaining the charging operation by Embodiment 3 of this invention. It is a figure explaining the charging operation by Embodiment 3 of this invention. It is a figure explaining the charging operation by Embodiment 3 of this invention. It is a figure explaining the charging operation by Embodiment 3 of this invention.

Explanation of symbols

8 Short-circuit switch
10 (10 pn1 to 10 pn3) charging capacitor as energy storage means,
11-13 single phase inverter, 41, 41a diode,
43, 43a Smoothing capacitor, 44 reactors,
45, 45a MOS transistor, 46, 46a charging diode,
110 single phase multiple converter,
120, 120a Switching regulator as a DC / DC converter,
G1 to G3 Single-phase inverter output.

Claims (9)

A power converter that outputs AC power to a connected load,
A plurality of single-phase inverters connected to the AC side in series,
A plurality of energy storage means respectively connected to the DC side of the plurality of single-phase inverters ;
A charging circuit for outputting DC power to the energy storage means;
A control circuit for controlling the plurality of single-phase inverters and controlling the power output to the load at a predetermined AC voltage ;
The plurality of single-phase inverters can output the electric power stored in the energy storage means connected to the AC side based on control of the control circuit,
The charging voltage of the plurality of energy storage means is set for each energy storage means,
One end of the charging circuit is connected to a first energy storage unit among the plurality of energy storage units,
The other end of the charging circuit is connected to a line parallel to the plurality of single-phase inverters ,
The control circuit, when storing power in a plurality of energy storage means other than the first energy storage means, a plurality of energy storage means to be subjected to a storage operation among the plurality of other energy storage means. Is connected in series with the charging circuit, and the energy storage means farthest from one end of the charging circuit among the plurality of energy storage means to be stored is connected to the line. A power conversion device that controls a plurality of single-phase inverters and the charging circuit. The charging voltage of the first energy storage means to which the charging circuit is connected is:
The power conversion device according to claim 1, wherein the power conversion device is equal to or higher than a charging voltage of the plurality of other energy storage units. The control circuit includes:
The timing of starting storage when storing power in the first energy storage means is different from the timing of starting storage when storing power in the other plurality of energy storage means.
Power converter according to claim 1 or 2, characterized in that for controlling said charging circuit and said plurality of single-phase inverters. The control circuit includes:
4. The power conversion device according to claim 3, wherein when the storage voltage of the first energy storage unit reaches a predetermined value, the storage of power in the plurality of other energy storage units is started. The control circuit includes:
The storage start timing when storing power in the first energy storage means is the same as the storage start timing when storing power in the plurality of other energy storage means.
The power converter according to claim 1, wherein the plurality of single-phase inverters and the charging circuit are controlled. The control circuit includes:
When the storage voltage of the predetermined energy storage means reaches a predetermined value, the predetermined single-phase inverter connected to the predetermined energy storage means is controlled so that the predetermined energy storage means is excluded from the target of the storage operation. The power conversion device according to any one of claims 1 to 5, wherein: The charging circuit is
A rectifier circuit that rectifies input AC power into DC power;
A switching circuit that outputs the rectified DC power,
The power converter according to any one of claims 1 to 6, wherein the rectifier circuit rectifies AC power output from an AC power supply connected to an AC side of the plurality of single-phase inverters . The control circuit includes:
The power converter according to claim 7, wherein the switching circuit is controlled by PWM control. The single-phase inverter is
Power converter according to any one of the switching elements from claim 1, characterized in that it comprises a circuit configured to connect to the full-bridge 8.

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