JP2002084763A - Inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To significantly increase electric energy to be taken out. SOLUTION: This inverter device comprises a plurality of DC-DC converting sections 39-42, and a plurality of DC-AC inverting sections 43-36. The DC-DC converting sections 39-42 take out maximum power separately from each DC power supply to increase the generated power. The plurality of DC-AC inverting sections 43-36 operate in minimum number necessary for the inversion of the power that the DC-DC converting sections 39-42 take out to conduct linkage to a system and stop the other DC-DC converting sections 39-42, thereby suppressing the circuit loss.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC power supply such as a solar cell or a fuel cell, and an inverter device for converting DC power obtained by rectifying AC power generated by wind power generation or wave power generation into AC power. It is.

[0002]

2. Description of the Related Art In recent years, it has been said that energy saving and resource saving have been described in the background of the problem of global warming due to increased carbon dioxide emission and the problem of depletion of fossil energy. Power generation using energy and power generation that does not emit carbon dioxide, such as fuel cells, are being promoted, and it is also necessary to develop an inverter device that links such energy to a commercial power supply system and injects power.

A conventional inverter device generally has a configuration as shown in FIG. Hereinafter, the configuration and operation will be described with reference to FIGS.

As shown in FIG. 10, 201 is a conventional 4k
The inverter device 201 is provided with a 4 kW rated DC-DC converter 239 and a 4 kW rated DC-AC converter 243. The output point of the DC-DC converter 239 and the DC-DC An electrolytic capacitor 247 is connected to a connection point between the input points of the AC converter 243. The input of the DC-DC converter 239 is provided with a current transformer 252 for detecting an input current and an input voltage detection circuit 256 for detecting an input voltage. The output of the current transformer 252 and the output of the input voltage detection circuit 256 ,
The DC-DC converter control circuit 248 is input to the DC-DC converter control circuit 248, and the output of the DC-DC converter control circuit 248 is connected to the DC-DC converter 239. DC-AC converter 243
Is connected to the commercial power system 206 via the system interconnection protection device 263, and the DC-AC converter 243 is connected to the DC-AC converter control circuit 262.

[0005] A solar cell array 300, which is a DC power supply input to the inverter device 201, is configured by connecting four solar cell strings 202 to 205 in parallel.
Each of the four solar cell strings 202 to 205 is configured by connecting eight solar cell modules in series. Solar cell string 202 and solar cell string 2
03 has a half area completely covered by the shadow. The power (P) -voltage (V) characteristics in this state are as shown in FIG. 11, respectively. The PV characteristics of the solar cell string 204 and the solar cell string 205 are shown in FIG.
It is as shown. As a result, the PV characteristics of the solar cell array 300 in which the solar cell strings 202 to 205 are connected in parallel are as shown in FIG.

When the inverter 201 operates, the DC-DC converter control circuit 248 causes the current transformer 25 to operate.
2, the DC-DC converter 239 controls the DC-DC converter 239 to extract the maximum power 2 kW of the solar cell array 300, and detects the input power from the output of the input voltage detection circuit 256. The DC power extracted and converted by the DC-DC converter 239 is converted into AC power and output to the system 206 via the system interconnection protection circuit 263.

[0007] Four solar cell strings 202 to 205
Is 3 kW by adding 0.5 kW of the solar cell string 202, 0.5 kW of the solar cell string 203, 1 kW of the solar cell string 204, and 1 kW of the solar cell string 205. The maximum generated power of the solar power array 300 taken out by the device 201 is 2 kW as shown in FIG.

[0008]

In such a conventional inverter device, only one DC-DC converter is provided irrespective of the number of solar cell strings, and the DC-DC converter is extracted from a solar cell array which is a DC power supply. The maximum power that can be obtained is 2 kW, and the maximum power of the individual solar cell strings constituting the solar cell array cannot be taken out individually, so that the power generation output from the inverter device is significantly reduced from the total power generation of the solar cells. was there.

Also, since there is only one input of the inverter device to which the DC power supply is connected, there are several types of DC power supplies, for example, a solar cell, and a power supply that rectifies and stores the output of wind power generation. However, there is also a problem that a system using the fuel cell and the fuel cell cannot be constructed. what if,
When these three DC power supplies are connected to each other via a reverse blocking diode and input to the inverter device, there is the same problem of reduction in the amount of power generation as described above.

Also, since only one DC-AC converter for converting the DC power converted by the DC-DC converter into AC power is provided, the DC-AC converter is rated for the inverter device. It is necessary to provide a rating equal to or higher than the maximum power of the DC power supply input to the power supply.

When the power smaller than the rated power of the DC-AC converter is converted, the operating frequency of the DC-AC converter increases, the loss of the DC-AC converter increases, and the power conversion efficiency decreases. is there. Also, when designing inverter devices with various power capacities corresponding to the power rating capacity of the inverter, or when slightly increasing the power rating capacity of the inverter after installation, the same rated capacity as the existing inverter device is used. For example, there is a problem that it is difficult to increase the number of units, and it becomes uneconomical.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and effectively draws out the power of a DC power supply, improves the power conversion efficiency as compared with the prior art, increases the amount of power generation output to the system, and provides various rated capacities. An object of the present invention is to provide an inverter device that can be easily coped with and can be easily added.

[0013]

In order to solve the above-mentioned problems, the present invention provides a plurality of DC-DC converters for converting a DC input into a DC output, and at least two or more of the plurality of DC-DC converters. The output and at least two or more inputs of a plurality of DC-AC converters are collectively connected.

[0014]

According to the first aspect of the present invention, a plurality of inputs to which a plurality of DC power supplies can be connected are provided, and a plurality of DC-DC converters corresponding to the respective DC power supplies operate independently. Therefore, the maximum power can be individually extracted from each DC power supply.

Further, the power of the plurality of DC power supplies is converted into a DC voltage by a DC-DC converter, and two or more outputs are connected together, so that the connected DC powers are summed up.
The total DC power is converted into divided AC power by a DC-AC converter connected to at least two or more inputs.

According to the second aspect of the present invention, if the outputs of the DC-AC converter are connected together, a plurality of DC powers can be collectively taken out as AC power.

According to the third aspect of the present invention, the plurality of DC power supplies are respectively connected to the inputs of the plurality of DC-DC converters, and each DC-DC converter follows the maximum power point of the plurality of DC power supplies. Therefore, the maximum power of the plurality of DC power supplies is always drawn.

According to the fourth aspect of the present invention, the divided DC-AC converter converts the DC power into AC power according to the output power of the plurality of DC-DC converters. Operate as many DC-AC converters as necessary to
Some DC-AC converters can be stopped, and as a result, the power conversion efficiency of the DC-AC converter can be improved.

According to the fifth aspect of the present invention, the module of the DC-DC converter and the module of the DC-AC converter divided into a plurality are provided so as to be attachable / detachable. -By changing the number of modules of the DC converter and the number of modules of the DC-AC converter, it is possible to cope with a system having various capacities, and the system can be easily added.

[0020]

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a 4 kW rated inverter device of the present invention. In the inverter device 1, DC-DC converters 39 to 42 divided into 1 kW rated portions,
DC-to-AC converters 43 to 46 divided into four W ratings are provided. Outputs of the four DC-to-DC converters 39 to 42 are collectively connected at point a, and four DC-to-AC converters are provided. The inputs of the units 43 to 46 are collectively connected at point x, and the outputs (point a) of the four connected DC-DC converters 39 to 42 and the four DC-AC converters 43 to 46 are connected together. (X point) are connected.

An electrolytic capacitor 47, which is a capacitor, is connected to a connection point b between the output points a of the four DC-DC converters 39 to 42 and the input points x of the four DC-AC converters 43 to 46. The collective connection of the four DC-DC converters 39 to 42 and the four DC-AC converters 43 to 46 is connected via an electrolytic capacitor. Inputs of the four DC-DC converters 39 to 42 are provided with current transformers 52 to 55 for detecting input current and input voltage detection circuits 56 to 59 for detecting input voltage, respectively. 55 output and input voltage detection circuit 56
To 59 are output from the DC-DC converter control circuit 4 respectively.
8 to 51, and the respective DC-DC converter control circuits 48 to 51 are connected to the DC-DC converter 3 respectively.
9 to 42.

A current transformer 60 is provided on a line connecting a point a to which the outputs of the four DC-DC converters 39 to 42 are connected together and a point b on the plus side of the electrolytic capacitor 47. An intermediate voltage detecting circuit 61 for detecting the voltage of the intermediate voltage detecting circuit 47 is provided.
The DC-AC converter control circuit 62 is input to the AC converter control circuit 62, and is connected to the four DC-AC converters 43 to 46. Also, four DC-AC converters 43-
The outputs 46 are collectively connected at a point y and input to the grid interconnection protection circuit 63.

The inverter device 1 according to the first embodiment is used in a photovoltaic power generation system using a solar cell as a DC power supply. Reference numeral 2 denotes a solar cell in which eight solar cell modules 7-14 are connected in series. 3 is a solar cell string in which eight solar cell modules 15 to 22 are connected in series, and 4 is an eight solar cell module 23 to 30
Is a solar cell string connected in series, 5 is a solar cell string in which eight solar cell modules 31 to 38 are connected in series, and among the eight solar cell modules 7 to 14 constituting the solar cell string 2, The photovoltaic modules 11 to 14 corresponding to half the area are completely covered with shadows, and half the area of the eight photovoltaic modules 15 to 22 constituting the photovoltaic string 3. Are in a state of being completely covered with shadows.

The solar cell string 2 is connected to input terminals 64 and 65 of the inverter 1, the solar cell string 3 is connected to input terminals 66 and 67 of the inverter 1, and the solar cell string 4 is connected to the inverter 1 Are connected to the input terminals 68 and 69 of the
Are connected to the input terminals 70 and 71 of the inverter device 1, and the solar cell strings 2 to 5 correspond to different DC power supplies, respectively. The output terminals 72 and 73 of the inverter device 1 are connected to the commercial power system 6.

Next, a specific schematic configuration of the DC-DC converter 39 and the DC-AC converter 43 will be described with reference to FIG.

In FIG. 2, an electrolytic capacitor 100 is connected to an input portion of the DC-DC converter 39. The positive side of the electrolytic capacitor 100 is connected to one end of a step-up coil 101. The collector terminal of the transistor 102, which is a switching element, is connected to the collector terminal of the transistor 102.
It is connected to the negative side of 0. The connection point between the coil 101 and the collector terminal of the transistor 102 is connected to the anode terminal of the diode 103, and the cathode terminal of the diode 103 is the output of the DC-DC converter 39.

A drive circuit 104 is connected to the base terminal of the transistor 102, and the drive circuit 104 is connected to the DC-DC converter control circuit 48. The configuration of the three DC-DC converters 40 to 42 other than the DC-DC converter 39 is the same as that of the DC-DC converter 39 in this embodiment.

Next, the configuration of the DC-AC converter 43 will be described. An arm in which a transistor 105 with a built-in flywheel diode as a switching element and a transistor 106 with a flywheel diode are connected in series, and an arm in which a transistor 107 with a built-in flywheel diode and a transistor 108 with a built-in flywheel diode are connected in series Two sets of arms are electrically connected in parallel with the electrolytic capacitor 47. The emitter terminal of the transistor 105 and the transistor 106
Is connected to one end of a coil 109, the other end of the coil 109 is connected to one end of a capacitor 110, and the other end of the capacitor 110 is connected to the emitter terminal of the transistor 107 and the collector terminal of the transistor 108. Connected to the connection point. Drive circuits 111 to 114 are connected to respective base terminals of the four transistors 105 to 108, and the four drive circuits 111 to 114 are connected to a DC-AC converter control circuit 62.

The operation of the inverter apparatus 1 using the four solar cell strings 2 to 5 configured as described above as a DC power supply will be described.

In the solar cell string 2, the four solar cell modules 7 to 10 are irradiated with solar radiation of a predetermined intensity, and the four solar cell modules 11 to 14 are not irradiated with solar radiation and are completely shaded. Covered. FIG. 3 is a characteristic diagram of the power P with respect to the voltage V of the solar cell string 2 in the solar radiation state.
The maximum is 5 kW. When the inverter device 1 operates in this state, the current transformer 52 detects the output current of the solar cell string 2 and outputs it to the DC-DC converter control circuit 48, and the input voltage detection circuit 56 outputs the output voltage of the solar cell string 2. And outputs it to the DC-DC converter control circuit 48.

The DC-DC converter control circuit 48 calculates the output power of the photovoltaic string 2 from the output of the current transformer 52 and the output of the input voltage detection circuit 56, and the output of the photovoltaic string 2 has a maximum power of 0.5 kW. The DC-DC converter 39 is controlled so that In the solar cell string 3, the four solar cell modules 15 to 18 are irradiated with solar radiation having the same intensity as described above, and the four solar cell modules 19 to 22 are not irradiated with solar radiation and are completely covered with shadows. Have been done.

FIG. 4 is a characteristic diagram of the electric power P with respect to the voltage V of the solar cell string 3 under the solar radiation condition. When the voltage is 100 V, the electric power is 0.5 kW, which is the maximum. The current transformer 53 detects the output current of the solar cell string 3 and outputs it to the DC-DC converter control circuit 49. The input voltage detection circuit 57 outputs
And outputs it to the DC-DC converter control circuit 49. The DC-DC converter control circuit 49 calculates the output power of the photovoltaic string 3 from the output of the current transformer 53 and the output of the input voltage detection circuit 57 so that the output of the photovoltaic string 3 has a maximum power of 0.5 kW. To control the DC-DC converter 40. Solar cell string 4
, All the solar cell modules 23 to 30 are exposed to the same intensity of solar radiation as described above.

FIG. 5 is a characteristic diagram of the electric power P with respect to the voltage V of the solar cell string 4 under the solar radiation conditions. Unlike the solar cell string 2 and the solar cell string 3, all the solar cell modules 23 to 30 are irradiated with the solar radiation. Therefore, when the voltage is 200 V, the electric power reaches a maximum of 1 kW. The current transformer 54 includes the solar cell string 4
, And outputs the output current to the DC-DC converter control circuit 50. The input voltage detection circuit 58 detects the output voltage of the solar cell string 4 and outputs the DC-DC converter control circuit 50.
Output to The DC-DC converter control circuit 50 calculates the output power of the photovoltaic string 4 from the output of the current transformer 54 and the output of the input voltage detection circuit 58, and controls the DC power so that the output of the photovoltaic string 4 has a maximum power of 1 kW. Control the DC converter 41; In the photovoltaic string 5, all the photovoltaic modules 31 to 38 are exposed to solar radiation having the same intensity as described above.

FIG. 6 is a characteristic diagram of the electric power P with respect to the voltage V of the solar cell string 5 under this solar radiation condition.
kW and the maximum. The current transformer 55 detects the output current of the solar cell string 5 and outputs it to the DC-DC converter control circuit 51. The input voltage detection circuit 59 detects the output voltage of the solar cell string 5 and controls the DC-DC converter. Output to the circuit 51. The DC-DC converter control circuit 51 calculates the output power of the solar cell string 5 based on the output of the current transformer 55 and the output of the input voltage detection circuit 59, and controls the DC power so that the output of the solar cell string 5 has a maximum power of 1 kW. Control the DC converter 42; Therefore,
The total value of the power that the inverter device 1 takes out from the solar cell strings 2, 3, 3, and 5 that are DC power supplies is 3 kW.
Becomes

The DC-DC converter 39 converts the power of 0.5 kW extracted from the solar cell string 2 into DC power having a voltage higher than the peak value of the commercial power supply system voltage.
The DC converter 40 converts the power 0.5 kW extracted from the solar cell string 3 into DC power having a voltage higher than the peak value of the commercial power system voltage, and the DC-DC converter 41
The power of 1 kW extracted from the solar cell string 4 is converted into DC power having a voltage higher than the peak value of the commercial power supply system voltage, and the DC-DC converter 42 converts the power of 1 kW extracted from the solar cell string 5 to the commercial power supply system voltage. The DC power is converted into a DC power having a voltage higher than the peak value, and the outputs of the four DC-DC converters 39 to 42 are connected together and output to the electrolytic capacitor 47.

The current transformer 60 detects the total output current of the four DC-DC converters 39 to 42 connected collectively and inputs the detected output current to the DC-AC converter control circuit 62.
The intermediate voltage detecting circuit 61 detects the voltage of the electrolytic capacitor 47 and inputs it to the DC-AC converter control circuit 62,
The AC converter control circuit 62 outputs four DC-DC signals based on the output of the current transformer 60 and the output of the intermediate voltage detection circuit 61.
Calculate the total output power of the DC converters 39 to 42,
Among the four DC-AC converters 43 to 46 rated at 1 kW divided into four according to the magnitude of the power, the DC-
The number of AC converters is controlled to the minimum necessary. That is, since the total output power of the four DC-DC converters 39 to 42 is 3 kW, the DC-AC converter control circuit 62 determines that the DC-AC converter 43, the DC-AC converter 44 and the DC-AC Three of the converters 45 are operated, and one of the DC-AC converters 46 is stopped. The three DC-AC converters 43 to 45 convert the DC power of the electrolytic capacitor 47 into AC power, and output the AC power to the commercial power system 6 connected to the output terminals 72 and 73 via the system interconnection protection circuit 63. Is done.

As described above, according to the inverter device 1 of the first embodiment of the present invention, the four DC-DC converters 3
Four solar cell strings 2 in which 9 to 42 are DC power supplies
5 can be individually taken out, and the DC-AC converter control circuit 62 does not need to operate the DC-AC converters among the four DC-AC converters 43 to 46. Since it is possible to stop and reduce useless circuit loss, the amount of power output to the commercial power supply system 6 can be significantly increased.

In the first embodiment, as the plurality of DC power supplies, a solar cell string in which eight solar cell modules of the same specification are all connected in series is used, but the solar cell modules constituting the solar cell string are different. The solar cell modules may be of different specifications, and the number of solar cell modules connected in series may be different for each solar cell string.
Also, as the plurality of DC power supplies, not all need to be solar cell strings, and some are different DC power supplies, for example,
A fuel cell or a device that rectifies the output of wind power or wave power and stores the power may be used.

Further, as the plurality of DC-DC converters,
There is no need to have four, and the plurality of DC-AC converters need not have four.

Further, in the first embodiment, the ratings of the four DC-DC converters are the same at 1 kW, but they are not required to be 1 kW, nor do they need to be the same. Although the ratings of the four DC-AC converters were the same at 1 kW, they did not need to be 1 kW nor did they need to be the same.

There are no particular restrictions on the specific configuration of each of the DC-DC converter and the DC-AC converter, and any configuration may be used.
Any component such as T may be used.

The DC-DC converter control circuit may have any function of following the maximum power of the DC power supply, and other control functions may be used.

Further, the DC-AC converter control circuit performs power detection for determining the number of DC-AC converters to be operated on the output side of the four DC-DC converters. The power may be detected on the input side of the DC converter and the number of DC-AC converters to be operated may be determined using the sum of the detected power.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to FIGS.

In FIG. 7, reference numeral 100 denotes a housing of the inverter device rated at 4 kW according to the present invention.
Four DC-DC converter modules 101 to 1 with W rating
04 and four DC-AC converters 105-1 kW rated.
108 are provided. The DC-DC converter module 101 includes a DC-DC converter 109 and a DC-DC converter control circuit 110.
Reference numeral 02 denotes a DC-DC converter 111 and a DC-DC converter controller 112, and the DC-DC converter module 10
Reference numeral 3 denotes a DC-DC converter 113 and a DC-DC converter control circuit 114.
Comprises a DC-DC converter 115 and a DC-DC converter control circuit 116, and the DC-AC converter module 105 comprises a DC-AC converter 117 and a DC-AC converter control circuit 1.
The DC-AC converter module 106 includes a DC-AC converter 119 and a DC-AC converter control circuit 12.
0, the DC-AC converter module 107 includes a DC-AC converter 121 and a DC-AC converter control circuit 122.
The DC-AC converter module 108 is a DC-AC converter.
It comprises an AC converter 123 and a DC-AC converter control circuit 124.

The input of the power line of the DC-DC converter module 101 is connected to wiring in the housing 100 by plug-in connectors 125 and 126, and the output of the power line of the DC-DC converter module 101 is plug-in connector 127. And 128, the signal lines of the DC-DC converter control circuit 110 for controlling the DC-DC converter 109 are connected to the wires in the housing 100 by plug-in connectors 129. , DC-DC converter module, these plug-in connectors 125-
129 can be freely attached and detached. Similarly, the DC-DC converter module 102 can be freely attached and detached by plug-in connectors 130 to 134, and the DC-DC converter module 103 can be freely attached and detached by plug-in connectors 135 to 139. The DC-DC converter module 104 includes plug-in connectors 140 to 1
Attachment / removal is made freely by 44.

The DC-AC converter module 105
Power line inputs are plug-in connectors 145 and 1
46 is connected to the wiring in the housing 100, and the output of the power line of the DC-AC converter module 105 is connected to the wiring in the housing 100 by plug-in connectors 147 and 148 to control the DC-AC converter 117. The signal line of the DC-AC converter control circuit 118 is connected to the plug-in connector 1.
The DC-AC converter module is connected to the wiring in the housing 100 at 49.
The attachment and detachment can be freely performed by using 45 to 149.

Similarly, the DC-AC converter module 10
6 can be freely attached and detached by plug-in connectors 150 to 154, and the DC-AC converter module 107 is provided with plug-in connectors 155 to 159.
Can be attached and detached freely.
The AC converter module 108 includes the plug-in connector 1
The attachment / detachment is made freely by 60 to 164. Four DC-DC converter modules 101 to 10
4 are collectively connected, the respective inputs of the four DC-AC converters 105 to 108 are also collectively connected, and the four DC-DC converter modules 101 to 104 connected collectively are connected. The output and the inputs of the four DC-AC converter modules 105 to 108 are connected,
A capacitor 165 is connected to the connection point.

Four DC-AC converter modules 105
To 108 are collectively connected to the system interconnection protection circuit 1
66 has been entered. The housing 100 includes a control circuit 167 for controlling the entire system interconnection DC-AC converter unit.
The control circuit 167 includes four DC-DC converter control circuits 110, 112, 114, and 116 and four DC-AC converter control circuits 118, 120, 122,
124.

The operation of the system interconnection DC-AC converter unit thus configured will be described.

Four DC-DC converter modules 101
１０４104 take out the maximum power of the DC power supply (not shown) connected to each, convert it to another DC power and output it to the capacitor 165, and the four DC-AC converter modules 105 to 108 Is converted to AC and output to a system (not shown). The control circuit 167 includes four DC-DC converter modules 101 to 101
The number of DC-AC converters to be activated or deactivated is controlled in accordance with the magnitude of the total output power of 104. The basic operation of the grid-connected DC-AC converter is the same as that of the first embodiment, and the second embodiment is characterized by the mounting of the grid-connected DC-AC converter.

As described above, according to the second embodiment of the present invention,
A DC-DC converter and a DC-DC converter control circuit for controlling the same are integrated into a detachable DC-DC converter module, and a DC-AC converter and a DC-AC converter for controlling the same. The DC-AC converter module, which can be easily attached and detached, is integrated with the power supply control circuit, so that the rating of the DC-AC converter unit can be easily changed according to the system capacity, and the system capacity can be changed. Can be easily added.

For example, when constructing a solar power generation system in which three 1 kW-rated solar cells 168 to 170 as shown in FIG.
Case 10 of system interconnection DC-AC converter unit shown in FIG.
By removing the DC-DC converter module 104 and the DC-AC converter module 108 within 0, a 3 kW rated system interconnection DC-AC converter device can be easily configured using the same casing 100, , Add more solar cells 1
It can be easily realized in the kW range.

Note that, as shown in FIG.
In the case where three of the kW-rated solar cell 168 and two 0.5 kW-rated fuel cells are input, three DC-DC converter modules 101 to 103 are used, and a DC-DC converter is used.
If the AC converter module is configured to use two of 105 and 106, unnecessary circuit loss can be eliminated and the cost of the device can be reduced.

The DC-DC converter module and the DC-AC converter module may be integrated on a printed wiring board, and the connection between these modules and the wiring in the housing may be made by a connector, a screw, or the like. May be used.

[0057]

As described above, according to the first aspect of the present invention, a plurality of DC-DC converters are provided corresponding to DC power supplies having different ratings (voltage, power, etc.). A plurality of DC-DC converters can individually extract the maximum power of the DC power supply that is input to each,
The amount of power to be extracted can be greatly increased as compared with the conventional case where power is extracted by a single DC-DC converter from DC power supplies of different ratings connected together.

Further, the conventional configuration comprising one DC-DC converter and one DC-AC converter is divided into a plurality of parts respectively to constitute the DC-DC converter and the DC-AC converter. Therefore, it is possible to use general mass-produced components, and it is also possible to reduce the cost of the system interconnection DC-AC converter.

According to the fourth aspect of the present invention, the DC-AC converters of a number required for converting the power among the plurality of DC-AC converters in accordance with the power of the DC power supply. Since the DC-AC converter can be operated and the other DC-AC converters can be stopped, the circuit loss can be reduced, and the efficiency of the grid-connected DC-AC converter can be improved as compared with the related art.

In particular, according to the fifth aspect of the present invention, a DC-DC converter in which a DC-DC converter is integrated with its controller is provided.
A DC-to-DC converter module, and a DC-to-AC converter module that integrates a DC-to-AC converter and its controller are provided.
Since the unit can be freely attached to and detached from the main unit, if a DC-DC converter module and a DC-AC converter module with a predetermined unit power are designed and prepared, the rating of the device can be freely adjusted in a predetermined unit. It can be constructed and can be easily expanded.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram when a system interconnection DC-AC converter unit according to a first embodiment of the present invention is used in a solar power generation system;

FIG. 2 is a specific schematic circuit configuration diagram of a DC-DC converter and a DC-AC converter of the device.

FIG. 3 is a characteristic graph of power with respect to the voltage of a solar cell string 2 which is a DC power supply input to the device.

FIG. 4 is a characteristic graph of power with respect to the voltage of a solar cell string 3 which is a DC power supply input to the device.

FIG. 5 is a characteristic graph of power with respect to the voltage of a solar cell string 4 which is a DC power supply input to the device.

FIG. 6 is a characteristic graph of power with respect to the voltage of a solar cell string 5 which is a DC power supply input to the device.

FIG. 7 is a configuration diagram of a system interconnection DC-AC converter unit according to a second embodiment of the present invention;

FIG. 8 is a system configuration diagram when the same device is used for a solar power generation system.

FIG. 9 is another system configuration diagram when the same device is used for a solar power generation system.

FIG. 10 is a system configuration diagram when a conventional system interconnection DC-AC converter unit is used in a solar power generation system.

FIG. 11 is a characteristic graph of power with respect to the voltage of a solar cell string constituting a solar cell array which is a DC power supply input to the device.

FIG. 12 is a characteristic graph of power with respect to the voltage of a solar cell string constituting a solar cell array which is a DC power supply input to the device.

FIG. 13 is a characteristic graph of power with respect to the voltage of a solar cell array which is a DC power supply input to the device.

[Explanation of symbols]

 39-42 DC-DC converter 43-46 DC-AC converter 1 Grid-connected DC-AC converter 2-5 Solar cell string (DC power supply) 47 ... Electrolytic capacitor (capacitor of claim) 6 Commercial power system (system of claims) 48-51 DC-DC converter control circuit 62 DC-AC converter control circuit 168-170 Solar cell (DC power) 172, 173 Fuel cell (DC power) ) 109, 111, 113, 115 DC-DC converter 117, 119, 121, 123 DC-AC converter 165 Capacitor 100 Housing 171 System 101-104 DC-DC converter module 105-108 ... DC-AC converter module

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02M 3/155 H02M 3/155 WF 7/5387 7/5387 Z (72) Inventor Hideki Omori Kadoma, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Shinichiro Sumiyoshi 1006 Ojimon Kadoma, Osaka Pref.Matsushita Electric Industrial Co., Ltd. (72) Inventor Takahiro Miyauchi 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term (reference) 5G066 HA06 HB03 HB05 5H007 AA04 AA07 BB07 CA01 CB05 CC05 CC12 DA04 DC02 DC05 GA05 GA06 GA08 GA09 HA04 5H420 BB14 CC03 CC06 DD02 EA11 EA48 EB04 EB37 FF03 FF04 FF22 5H730 AA14 BB14 BB57 BB82 DD02 FD11 FD41

Claims (5)

[Claims] 1. A plurality of DC-DC converters for converting a DC input into a DC output, at least two or more outputs of the plurality of DC-DC converters, and at least two of the plurality of DC-AC converters Inverter device with the above inputs connected together. 2. The inverter device according to claim 1, wherein outputs of the plurality of DC-AC converters are collectively connected, and a sum of output powers of the plurality of DC-DC converters is converted into AC power and output. 3. The inverter device according to claim 1, wherein the plurality of DC-DC converters are controlled so as to extract the maximum power of the DC power supplied to each of the DC-DC converters. 4. A plurality of DC-DC converters according to a total value of input powers of the plurality of DC-DC converters or a total value of output powers of the plurality of DC-DC converters. 2. The inverter device according to claim 1, further comprising a DC-AC converter control unit that controls the number of DC-AC converters operated by the AC converter and the number of inverters of the DC-AC converter that is stopped. 5. A plurality of DC-DC converters and DC-AC converters, each of which is constituted by a module which can be easily attached / detached one by one. An inverter device in which the power rating of the inverter device is determined by adjusting the number of attached modules of the AC converter, and the module is housed in the housing.