JP2004200326A - Power conversion apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power conversion apparatus which can be connected to DC power supplies of different output voltages. <P>SOLUTION: The power conversion apparatus receives electric power sent from a plurality of DC power supplies including solar cells and converts them to output. The power conversion apparatus is equipped with a plurality of switches connected to corresponding DC power supplies 5, 6, and 7; a switching control circuit 16 driving the switches by signals synchronizing with a single signal source; a transformer 19 equipped with a plurality of primary windings connected to the corresponding switches and a secondary winding; and a plurality of switching circuits which connect the DC power supplies, the switches, and the primary windings so as to form an electrically independent current loop. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to power conversion for converting powers input from a plurality of DC power supplies including solar cells, collecting the powers, and outputting the collected powers.
[0002]
[Prior art]
In recent years, a photovoltaic power generation system has been developed in which a distributed power supply using solar power and a commercial power supply system are interconnected, and when the power cannot be provided solely by the distributed power supply, the power is supplied from the grid side. I have.
[0003]
FIG. 9 is a diagram showing an example of a schematic configuration of such a conventional solar power generation system 50. The photovoltaic power generation system 50 configures a photovoltaic cell array by connecting a plurality of photovoltaic modules 55 arranged in, for example, a roof of a general house in series and parallel as shown in FIG. It is configured to convert DC power into AC power synchronized with a commercial power supply and to be connected to the grid via a solar inverter 51 having a grid connection protection function. (For example, see Patent Document 1)
[0004]
FIG. 10 is a diagram showing a connection configuration between the plurality of solar cell modules 55 of FIG. 9 and the solar inverter 51. In this conventional example, two solar cell strings 56-1 and 56-2 in which eight solar cell modules 55 are connected in series are connected in parallel to each other via backflow prevention diodes 58-1 and 58-2. It is configured to be connected to the inverter 51.
[0005]
In the solar inverter 51, a DC / DC converter in which the output voltage is suppressed for safety reasons and the output voltage of the solar cell strings 56-1 and 56-2 that fluctuates due to solar radiation and temperature is increased to a constant voltage; A DC / AC converter for converting the output into a cross-current is built in, and the output of the solar inverter 51 is connected to a commercial power supply system.
[0006]
Here, the upper limit of the voltage, that is, the number of series solar cell modules of the solar cell strings 56-1 and 56-2 is limited for safety reasons, and the number of solar cell modules of each solar cell string is also limited. Must be the same.
[0007]
This is because, when different numbers of solar cell strings are connected in parallel, the output voltage of each string is different, and the solar inverter 51 is supplied with power only from the string with the higher output voltage and supplied with power from the string with the lower output voltage. It is because it is not done.
[0008]
In addition, when a plurality of solar cell strings of the same serial number are installed on a roof or the like while satisfying the upper limit of the number of solar cell modules connected in series, an odd region is generated. That is, although several solar cell modules can be installed, an area insufficient for installing one solar cell string occurs.
[0009]
Usually, dummy solar cell modules are installed in such an odd area. That is, from an aesthetic point of view, a dummy solar cell module for decorative purposes having no power generation function is installed in an odd area.
[0010]
On the other hand, in order to reduce such an odd area, the boost converter is connected to a small number of solar cell strings in series without using the same number of solar cell strings in series, and the voltage of each solar cell string is the same. A method of collecting current in parallel is known. For example, in Patent Literature 1, as shown in FIGS. 11 and 12, by connecting a solar cell string 57 having a small number of solar cell modules to a boost converter 59 and boosting the voltage, other solar cell strings 56-1 and 56 are obtained. The current is collected in parallel by setting the same voltage as -2.
[0011]
However, the above prior art has the following problems.
[0012]
First, regarding the method of installing a dummy solar cell module, despite the area where the solar cell module can be installed, there is an area that does not generate electricity, so that the generated power cannot be obtained for that area. There is a problem that the power generation per unit is reduced.
[0013]
In addition, as in Patent Document 1 shown in FIGS. 11 and 12, in a system in which the boost converter 59 is attached to a solar cell string 57 having a small number of solar cell modules 55 in series, the DC / DC converter 51 included in the solar inverter 51 is used. This necessitates the use of the boost converter 59 in addition to −1, which may cause an increase in the cost of the device and an increase in space.
[0014]
Another problem is that since the solar cell strings are not insulated (for example, between 56-1 and 56-2 in FIG. 10A), a ground fault occurs at a place where the potential between different solar cell strings is different. In this case, there is also a problem that a power generation loss occurs due to a ground fault circulating current flowing.
[0015]
[Patent Document 1]
JP-A-9-261949
[0016]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the related art, and an object of the present invention is to provide a power conversion device capable of connecting a DC power supply having a different output voltage.
[0017]
Means for Solving the Invention
The power converter of one embodiment according to the present invention for achieving the above object has the following configuration. That is, a power converter that is connected in parallel to a plurality of DC power supplies including a solar cell, converts power input from each DC power supply, collectively outputs the plurality of switches, and a plurality of switches corresponding to the plurality of DC power supplies. A switching control circuit that drives the plurality of switches with a signal synchronized with a single signal source; a plurality of primary windings corresponding to the plurality of DC power supplies; and a single secondary winding. And forming a current loop connecting the DC power supply, the switch, and the primary winding for several of the plurality of DC power supplies.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is a power converter that is connected in parallel to a plurality of DC power supplies including a solar cell, converts power input from each DC power supply, and collectively outputs the plurality of DC power supplies. At least a switch, a switching control circuit that drives the plurality of switches with signals synchronized with a single signal source, a plurality of primary windings corresponding to a plurality of DC power supplies, and a single secondary winding And a current loop connecting the DC power supply, the switch, and the primary winding for several DC power supplies.
[0019]
The present invention as described above can be specifically realized in the configuration shown in FIGS. 1 to 12 in correspondence with the following first to fourth embodiments.
[0020]
[First Embodiment]
Embodiments of the present invention will be described in detail with reference to the drawings.
[0021]
FIG. 1 shows a system configuration diagram of a photovoltaic power generation system employing the present invention.
[0022]
[System configuration of solar power generation system: Fig. 1]
The system of FIG. 1 includes a solar cell unit 1 that receives sunlight and outputs power energy, a power collection / power conversion unit 2 that collects power generated by the solar cell unit 1 and converts the power to a commercial system frequency, / The power output from the power conversion unit can be broadly classified into a system interconnection unit 3 for flowing into a commercial system. Hereinafter, the configuration will be described step by step.
[0023]
(Constitution)
[Solar cell part 1]
The solar cell unit 1 according to the present embodiment is installed on the roof of a house, and is configured as follows.
[0024]
● Solar cell module 4
As the solar battery cell used in the present invention, those using an amorphous silicon-based photoelectric conversion unit, those using polycrystalline silicon, or crystalline silicon are preferably used. A solar cell module 4 is configured by connecting a plurality of these solar cells in series. In the present embodiment, the amorphous solar cell modules 4 (nominal output 50 W, maximum output operating voltage = 25 V) are used and connected in series to form solar cell strings 5, 6 and 7.
[0025]
● Solar cell strings 5, 6, 7
By connecting a plurality of solar cell modules 4 in series, solar cell strings 5, 6, 7 are configured. The number of series solar cells constituting the solar cell string may be appropriately set so as to obtain a voltage required for a solar power generation device, but in a system for a private house, a voltage of about 200 V is set. Often.
[0026]
The roof on which the solar cells are installed in the present embodiment has an area where 20 solar cell modules 4 can be installed, and the upper limit voltage of the solar cell string is set to about 200 V. , 8 solar cell strings in series and 2 solar cell strings in 4 series.
[0027]
Each of the solar cell strings 5 and 6 has an output voltage of 200 V by connecting eight solar cell modules 4 in series. (Output 400W)
The solar cell string 7 is configured by connecting four solar cell modules left in an odd space left on the roof in series, and has an output voltage of 100 V and an output of 200 W.
[0028]
In this way, solar cells of a total of 1 kW (400 W × 2 + 200 W) for the solar cell strings 5, 6, and 7 are installed in the power collection / power conversion unit 2, and the generated power is supplied to the power collection / power conversion unit 2. Sent out.
[0029]
[Current collection / power conversion unit 2]
The power collection / power conversion unit 2 collects the power generated by the solar cell unit 1 including a plurality of solar cell strings 5, 6, 7 as shown in FIG. Output to The operation of the power collection / power conversion unit 2 will be described in detail separately.
[0030]
[System interconnection section 3]
The grid interconnection unit 3 sells AC power of the commercial frequency output from the photovoltaic power generation system to the commercial grid or transmits the power to the home power load, and also uses the power used by the power load as the power generated by the photovoltaic power generation system. In the event that it cannot be covered, it is responsible for purchasing power from the commercial system and supplying it to the load.
[0031]
The switchboard 8 is installed in a building (consumer), and indoor wiring is branched from the switchboard 8 so as to supply power from the switchboard 8 to lighting equipment in the building section and a domestic load 10 connected to an outlet 9 or the like. ing. A main breaker 8-1 for separating the indoor wiring from the commercial power system 12 is installed on the switchboard 3, and a branch breaker 8-2 is installed on each of the indoor wiring branches off from the switchboard 8.
[0032]
The commercial power system 12 is supplied into the building via a power path, and a power trading meter 11 is installed on the way. Inside the power buying and selling meter 11, a power buying meter 11-1 for integrating the amount of power supplied from the power path into the building, and an amount of power flowing backward from the photovoltaic power generator to the commercial power system 12 are stored. The power selling meters 11-2 to be integrated are connected in series.
[0033]
[Configuration of power collection / power conversion unit 2: FIG. 2]
FIG. 2 shows the configuration of the power collection / power conversion unit 2.
[0034]
The power generated by the solar cell strings 5, 6, 7 is input to the power collection / power conversion unit 2 in an insulated state. They are magnetically coupled to the transformer 19 by different windings P1, P2, P3, respectively, via switching circuits 13-1, 13-2, 13-3, respectively.
[0035]
Each switching circuit 13-1, 13-2, 13-3 of the transformer winding corresponding to each solar cell string 5, 6, 7 has a backflow prevention diode 14-1, 14-2 in series with the transformer winding, respectively. , 14-3, switching elements 18-1, 18-2, 18-3, and smoothing capacitors 15-1, 15-2, 15-3 connected in parallel with the transformer windings, respectively.
[0036]
Each of the switching circuits 13-1, 13-2, and 13-3 in FIG. 2 has a reset winding and a diode for emitting a reset current, not shown, and constitutes a forward circuit.
[0037]
The windings are magnetically coupled to each other by an iron core of a transformer 19, and the windings P1, P2, and P3 are wound at a turn ratio of 2: 2: 1. This is because the following equation (1) is established between the output voltage of the solar cell string and the number of windings.
[0038]
V1: V2: V3 = P1: P2: P3-(1)
V1: Output voltage of solar cell string 5 (200V)
V2: output voltage of solar cell string 6 (200 V)
V3: output voltage of solar cell string 7 (100 V)
P1: the number of windings of the circuit to which the solar cell string 5 is connected
P2: the number of windings of the circuit to which the solar cell string 6 is connected
P3: number of windings of the circuit to which the solar cell string 7 is connected
[Transformer configuration: Fig. 3]
FIG. 3 shows the configuration of the transformer 19.
[0039]
The transformer 19 has a winding P1 to which the solar cell string 5 is connected, a winding P2 to which the solar cell string 6 is connected, a winding P3 to which the solar cell string 7 is connected, and a winding S for extracting the energy thereof. By being wound around the same iron core, it is magnetically coupled. The insulation between the windings is maintained by the interphase tape 40.
[0040]
Further, the windings P1 to P3 are wound with the number of windings satisfying the relationship of the expression (1), and since the ratio of V1: V2: V3 is 200V: 200V: 100V, the winding ratio of P1: P2: P3 is 2: 2: 1. In addition, since the transformer output voltage is 320 V, V1: output voltage = 200 V: 320 V, and the windings are wound with the number of windings at a ratio of P1: S of 5: 8. In the present embodiment, the number of windings is set as follows from the relationship between the core loss of the transformer and the winding conduction loss.
[0041]
P1 = 200 turns, P2 = 200 turns,
P3 = 100 turns, S = 320 turns
Each of the switching elements 18 is constituted by, for example, an FET or a bipolar transistor, and is switched on / off in synchronization with each other by a switching control circuit 16. Further, the drive signal from the switching control circuit 16 is configured to be insulated by the photocoupler 17 in order to maintain the insulation of each circuit.
A high frequency signal of several tens to several hundreds of kHz is transmitted from the switching control circuit 16, and the switching elements 18-1, 18-2, and 18-3 are switched at high speed by the same frequency and the same duty signal, and the transformer 19 generates power. Energy is transmitted.
[0042]
(Operation of power collection / power conversion unit 2)
The optimal operating point of the solar cell changes depending on the solar radiation and the temperature.
The optimal operating point voltage of the solar cell string 7 having four solar cell module series is の of the optimal operating point voltage of the solar cell strings 5 and 6 having eight solar cell module series. This is because the amount of solar radiation applied to the solar cell modules arranged on the same roof surface and the solar cell module temperature are equal.
[0043]
[Relationship between series number of solar cell modules, optimum operating voltage, and number of windings: FIG. 4]
FIG. 4 is a schematic diagram showing the relationship between the number of solar cell modules 4 connected in series, the optimum operating point voltage, and the number of transformer windings.
[0044]
Therefore, the switching elements 18-1, 18-2, 18-3 are operated with the same switching signal, and the winding ratio is made equal to the ratio of the solar cell string voltage, so that the solar cell strings 5, 6, 7 The power can be operated at the respective optimum operating point voltages.
[0045]
The generated power of the solar cell transformed and collected by the transformer is subjected to high-frequency switching in each of the switching circuits 13-1, 13-2, and 13-3, and then rectified by the rectifier circuit 20.
[0046]
The secondary winding of the transformer 19 is output to a single-phase 200V commercial power system via a rectifier circuit 20 and an inverter circuit 21.
[0047]
As described above, in this device, the output voltage of the solar cell string operates while maintaining the ratio of the expression (1) by making the switching signal of each switching element the same while having a simple configuration. Since the series number of the modules is different, it is possible to operate the solar cell strings 5, 6, 7 having different output voltages at the optimum operating point voltage.
[0048]
With such a configuration, it is possible to collect and output the power generated by the solar cell strings 5, 6, and 7 having different output voltages by the power collection / power conversion unit 2.
[0049]
As described above, in the power conversion device according to the first embodiment of the present invention, it is preferable that each of the plurality of DC power supplies be composed of a solar cell.
[0050]
Further, for example, the solar cell is preferably constituted by a solar cell string in which a plurality of solar cell modules having substantially the same output voltage are connected in series.
[0051]
Further, for example, different numbers of solar cell modules are connected in series to the solar cell strings, respectively, and the number of turns of the primary winding connected to each solar cell string is equal to the number of the connected solar cell modules. Preferably, it is determined accordingly.
[0052]
Further, for example, it is preferable to use the output in connection with a commercial power system.
[0053]
Note that the present invention can take an embodiment as a system, for example. Specifically, the present invention provides a solar light including a plurality of DC power supplies including a solar cell, and a power converter connected to the plurality of DC power supplies, converting power input from each DC power supply, and collecting and outputting the combined power. A power generation system, wherein the power conversion device supports a plurality of switches corresponding to a plurality of DC power supplies, a switching control circuit driving the plurality of switches by a signal synchronized with a single signal source, and a plurality of DC power supplies Having a plurality of primary windings and a transformer having at least a single secondary winding, and forming a current loop connecting the DC power supply, the switch, and the primary winding for several DC power supplies. It is characterized by doing.
[0054]
The power converter of the present embodiment can collect and output power in parallel even for solar cells having different output voltages by setting the input winding ratio to the voltage ratio of the solar cell string. Therefore, even when the output voltages of the plurality of solar cell strings are different from each other, it is not necessary to use the dummy solar cell module or the boost converter to equalize the output voltages of the respective solar cell strings.
[0055]
According to the present invention corresponding to the above-described embodiment, for example, there is obtained an effect that it is possible to provide a power converter capable of connecting DC power supplies having different output voltages.
[0056]
[Second embodiment]
Next, the power collection / power conversion unit 65 having a configuration similar to that described in the first embodiment is replaced with a system (hereinafter, a simple coating system) in which the insulation coating of the solar cell is simplified to reduce the cost. An embodiment to be applied will be described.
[0057]
In the present embodiment, in an environment where there is no risk of a user accidentally contacting a solar cell (hereinafter referred to as a management environment), a photovoltaic power generation system in which the current collection / power conversion unit 65 of the present invention is connected to a simple coating system. The system will be described.
[0058]
In the following description, the description common to that described in the first embodiment will be omitted, and only different points will be described. In the following description of the drawings, the same components in the drawings used in the description of the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted.
[0059]
[Problems of conventional simple coating system: FIG. 5]
First, problems of the conventional simple coating system will be described.
[0060]
The simple coating system simplifies the insulating coating of an expensive solar cell module to reduce the cost of the system. For this reason, the cost of the solar cell module can be reduced, but on the other hand, there is a high risk that the live parts of the solar cell module are exposed over time and the probability of a ground fault increases.
[0061]
FIG. 5 shows an example of a conventional simple coating system in which solar cell strings are electrically connected in parallel. It is assumed that a point A of the solar cell string 61 is R1Ω and a point B of the solar cell string 62 is R2Ω due to aging. In such a case, a closed circuit is formed with (R1 + R2) Ω for the entire solar cell array. Assuming that the output voltage of the solar cell array is 200 V, a power loss of 200 (V) × 200 (V) / (R1 + R2) always occurs in this case.
[0062]
[Application to simple coating system: Fig. 6]
On the other hand, FIG. 6 shows an example in which the current collection / power conversion unit 65 of the present invention is applied to a simple coating system. In the example of FIG. 6, a plurality (two) of solar cell strings (5 and 6) having the same output voltage are connected to the current collecting / power converting unit 65 such that current loops that are electrically independent of each other are formed. You.
[0063]
Note that the power collection / power conversion unit 65 of the present embodiment is different from the power collection / power conversion unit 2 because the two switching circuits (13-1 and 13-2) correspond to the two solar cell strings. The only difference is that the number of solar cell modules in each of the solar cell strings 5 and 6 is equal in series (eight in each case), so that the turns ratios of P4 and P5 are equal.
[0064]
In the configuration of FIG. 6, each of the solar cell strings 5 and 6 is magnetically connected in parallel while maintaining insulation, and power is collected and output. Therefore, even if the points A and B in FIG. 6 are respectively grounded, the solar cell strings 5 and 6 are kept insulated, and a closed circuit is formed in the entire solar cell array as shown in FIG. It is not formed. Therefore, even when the points A and B are grounded, there is no power loss due to the formation of a closed circuit, so that the power generated by the solar cell can be efficiently converted.
[0065]
As described above, in the power converter according to the second embodiment of the present invention, the same number of solar cell modules are connected in series to the solar cell strings, and the primary windings connected to the respective solar cell strings are wound. The numbers may all be equal.
[0066]
By using the power converter of the present invention corresponding to the above-described embodiment, even if the insulation coating of the solar cell is simplified and the cost is reduced, a ground fault occurs at a plurality of solar cell strings. Also, the effect of reducing the degree of power generation loss caused by the ground fault between the solar cell strings can be obtained.
[0067]
[Third Embodiment]
Next, the current collecting / power conversion unit 66 having a configuration similar to that described in the first embodiment is formed by stacking and insulating two types of solar cells having different light wavelength sensitivities, and without using a separate series connection. An embodiment in which the present invention is applied to a solar cell from which output is taken as a solar cell will be described.
[0068]
In the following description, the description common to that described in the first embodiment will be omitted, and only different points will be described. In the following description of the drawings, the same components in the drawings used in the description of the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted.
[0069]
In the present embodiment, the solar cell 100 according to the present invention is configured such that two types of solar cells having different light wavelength sensitivities are stacked and insulated, and an output can be taken out as a separate solar cell without being connected in series. The photovoltaic power generation system to which the / power conversion unit 66 is connected will be described.
[0070]
[Application to solar cells having different output voltages: FIG. 7]
As shown in the cross-sectional view of FIG. 7A, the power generation layer 101 has two power generation layers 101 and 111, electrodes 102 and 103 are provided on both surfaces of the power generation layer 101, and electrodes 112 and 113 are provided on both surfaces of the power generation layer 111. A structure in which an insulating layer 115 is provided and stacked between the electrode 103 and the electrode 112 is employed. The power generation layer 101 and the power generation layer 102 are electrically insulated by the insulating layer 115.
[0071]
By using materials having different wavelength sensitivities for the materials of the two power generation layers 101 and 111, the optical spectrum can be effectively used. In such a solar cell 100, the two types of solar cells (power generation layers 101 and 111) can be separately connected to the current collection / power conversion unit 66 without being connected in series, so that no IV mismatch occurs and the power generation layer It is not necessary to consider the current balance of 101 and 111. That is, as shown in FIG. 7B, two types of solar cells (power generation layers 101 and 111) can be used at different optimum operating point voltages.
[0072]
Therefore, when the present invention is applied to such a solar cell, by setting the ratio of the optimum operating point voltage of the two types of solar cells to the winding ratio of the first winding, both solar cells are always operated at the optimum operating point. It is possible to operate with a voltage.
[0073]
[Current collection / power conversion unit: Fig. 8]
The power collection / power conversion unit 66 in FIG. 8 is configured to output DC / DC by setting the ratio of the optimum operating point voltages of 101 and 111 to the ratio of the number of turns P6 and P7. The configuration such as driving the other switching elements with the same drive signal is the same as the configuration of the first embodiment and the second embodiment.
[0074]
As described above, in the power conversion device according to the third embodiment of the present invention, the solar cell is formed by stacking solar cells having power generation layers having different photoelectric conversion sensitivities to light wavelengths. It is preferable to take out different output voltages separately and use them as each DC power supply.
[0075]
Further, for example, it is preferable that the number of windings of the primary winding connected to each DC power supply is determined according to the output voltage output from the power generation layer.
[0076]
As described above, the present invention is applied to a solar cell in which two types of solar cells having different light wavelength sensitivities are stacked and insulated, and output is obtained as a separate solar cell without being connected in series. In one power converter, it is possible to provide a device capable of collecting and outputting power in parallel.
[0077]
[Fourth embodiment]
The power collection / power conversion unit having the configuration described in the first embodiment can be applied to a configuration in which current collection is performed in parallel by combining a solar cell and another energy source, for example, a storage battery. For example, in the case where a solar cell and a storage battery are combined, the solar cell and the storage battery are insulated, and as described in the first embodiment, each voltage ratio is set to the first winding ratio, so that one unit is collected. A system for collecting current in parallel while maintaining insulation in the power / power conversion unit can be configured. Note that the configuration of the switching circuit (the number of switching circuits, the number of windings, and the like) of the power collection / power conversion unit may be appropriately changed according to the number of solar cells and storage batteries that collect current in parallel.
[0078]
As described above, the power converters according to the first to fourth embodiments collect parallel currents even for solar cells having different output voltages by setting the input winding ratio to the voltage ratio of the solar cell string. , Can be output. Therefore, even when the output voltages of the plurality of solar cell strings are different from each other, it is not necessary to use the dummy solar cell module or the boost converter to equalize the output voltages of the respective solar cell strings.
[0079]
In addition, since it is possible to collect and output power while maintaining the insulation of a plurality of solar cell strings, for example, it is possible to simplify the covering of the solar cell, and even if a ground fault occurs in a plurality of Since no current flows, power loss can be reduced.
[0080]
In addition, by collecting current in parallel with a single current collection / power conversion unit while maintaining the insulation of a plurality of solar cells, the size and cost can be reduced compared to a device that performs power conversion with multiple current collection / power conversion units. Can be. Further, by using the same drive signal for the switch means, it is possible to further reduce the cost.
[0081]
【The invention's effect】
As described above, according to the power converter of the present invention, it is possible to connect DC power supplies having different output voltages.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a solar power generation system according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating details of a current collection / power conversion unit.
FIG. 3 is a diagram illustrating a configuration of a transformer.
FIG. 4 is a schematic diagram showing the relationship between the number of series solar cell modules and the turn ratio.
FIG. 5 is a diagram showing a problem at the time of parallel connection in a conventional solar power generation system.
FIG. 6 is a configuration diagram of a solar power generation system (Embodiment 2) according to one embodiment of the present invention.
FIG. 7 is a cross-sectional view of a solar cell used in a solar power generation system (Embodiment 3) according to one embodiment of the present invention.
FIG. 8 is a configuration diagram of a photovoltaic power generation system (Embodiment 3) according to an embodiment of the present invention.
FIG. 9 is a diagram schematically showing a conventional solar power generation system.
FIG. 10 is a diagram schematically showing a conventional solar power generation system.
FIG. 11 is a view schematically showing a conventional solar power generation system.
FIG. 12 is a diagram schematically showing a conventional solar power generation system.
[Explanation of symbols]
1. Solar cell part
2. Power collection / power conversion unit
3: Grid connection
4: Solar cell module
5, 6, 7 ... solar cell string
8. Distribution board
9… Outlet
10… Home load
11 ... Trading meter
12 ... Commercial system
14 ... Backflow prevention diode
15 ... Input smoothing capacitor
16 Switching control unit
17 ... Photo coupler
18 Switching element
19 ... Insulation transformer
20: Secondary side rectifier circuit
21 ... Inverter circuit
51… Solar inverter
55… Solar cell module
56-1, 56-2 ... solar cell string
58-1, 58-2 ... Backflow prevention diode
65, 66 ... power conversion device

Claims (1)

A power converter that is connected in parallel to a plurality of DC power supplies including solar cells, converts power input from each DC power supply, and collectively outputs the power.
A plurality of switches corresponding to the plurality of DC power supplies;
A switching control circuit that drives the plurality of switches with a signal synchronized with a single signal source;
A plurality of primary windings corresponding to the plurality of DC power supplies, and a transformer having at least a single secondary winding,
A power converter, comprising: a current loop connecting the DC power supply, the switch, and the primary winding for several of the plurality of DC power supplies.

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