KR101954195B1 - Power converting apparatus, and photovoltaic module - Google Patents

Abstract

The present invention relates to a power conversion device and a solar module. A power conversion apparatus according to an exemplary embodiment of the present invention includes a switching unit having a switching device and for switching the input DC power to selectively output the DC power, a power supply unit having a tap inductor and a switching device, And an inverter for converting the level-converted DC power into an AC power, wherein the converter operates in a first power conversion mode during a turn-off period of the switching element of the switching unit, During the turn-on period of the negative switching element, the converter operates in the second power conversion mode. As a result, the output current quality can be improved.

Description

Power conversion apparatus, and photovoltaic module (Power converting apparatus, and photovoltaic module)

The present invention relates to a power conversion device and a solar module, and more particularly, to a power conversion device and a solar module capable of improving output current quality.

With the recent depletion of existing energy sources such as oil and coal, interest in alternative energy to replace them is increasing. Among them, solar cells are attracting attention as a next-generation battery that converts solar energy directly into electrical energy using semiconductor devices.

On the other hand, the photovoltaic module means that solar cells for solar power generation are connected in series or parallel, and the photovoltaic module can include a junction box for collecting the electricity produced by the solar cell.

An object of the present invention is to provide a power conversion device and a solar module capable of improving output current quality.

According to an aspect of the present invention, there is provided a power conversion apparatus comprising: a switching unit having a switching device for switching an input DC power to selectively output a DC power; The converter includes a plurality of switching elements and an inverter for converting the level-converted DC power into an AC power. During a turn-off period of the switching element of the switching part, Mode, and during the turn-on period of the switching element of the switching unit, the converter operates in the second power conversion mode.

According to another aspect of the present invention, there is provided a solar module including: a solar cell module having a plurality of solar cells; a power conversion unit converting a DC power supplied from the solar cell module and converting the DC power into an AC power Wherein the power conversion unit includes a switching unit having a switching device for switching the input DC power and selectively outputting the DC power, a converter having a tap inductor and a switching device, for level-converting the DC power from the switching unit, And an inverter which has a plurality of switching elements and converts the level-converted DC power into AC power. During the turn-off period of the switching element of the switching part, the converter operates in the first power conversion mode, During the turn-on period, the converter operates in the second power conversion mode.

According to the embodiment of the present invention, the converter connected to the switching section is divided into the boost mode or the buck mode in accordance with the turn-on or turn-off of the switching element of the switching section in the power conversion apparatus or the solar module, Quality can be improved.

Particularly, when the converter outputs the pseudo direct current power and the constant voltage maintaining section occurs, the constant voltage is lowered to the ground voltage, so that a desired output AC power source waveform can be obtained and the output current quality can be improved. Particularly, the influence of the harmonic current component can be reduced.

The ripple of the current component output from the converter is reduced, and thus the reliability of the capacitor disposed at the front end of the converter can be ensured.

On the other hand, the power conversion device or the solar module is provided with the tap inductor boost converter, thereby ensuring a high-efficiency high-voltage direct current power source.

On the other hand, the power conversion device or the solar module may include a plurality of tap-inductor boost converters connected in parallel with each other, thereby reducing the ripple of the current component output from the converter, It is possible to secure the reliability of the capacitor disposed at the negative end.

On the other hand, the power conversion device or the solar module may include a plurality of tap inductor boost converters connected in parallel with each other, and each converter can perform an adaptive operation according to the required power, thereby improving the power efficiency.

1 is a front view of a solar module according to an embodiment of the present invention.
Fig. 2 is a rear view of the solar module of Fig. 1;
3 is an exploded perspective view of the solar cell module of FIG.
4 is an example of a bypass diode configuration of the solar module of FIG.
Fig. 5 illustrates a voltage versus current curve of the solar module of Fig.
6 illustrates a voltage versus power curve of the solar module of FIG.
7 is an example of an internal circuit diagram of a power conversion apparatus according to an embodiment of the present invention.
8 is a simplified block diagram of the power converter of FIG.
9A and 9B illustrate an embodiment and a comparative example of the output current outputted from the power conversion apparatus of FIG.
10A to 10D are diagrams for explaining the operation of the switching unit and the converter in the power conversion apparatus of FIG.
11 to 13 are views referred to for explaining the operation of the power conversion apparatus of FIG.
14 is another example of the internal circuit diagram of the power conversion apparatus according to the embodiment of the present invention.
15 is another example of the internal circuit diagram of the power conversion apparatus according to the embodiment of the present invention.
16 illustrates an internal circuit diagram of a junction box of the solar module of Fig.
17 is an example of a configuration diagram of a solar photovoltaic system according to an embodiment of the present invention.
FIG. 18 is another example of the configuration diagram of the solar photovoltaic system according to the embodiment of the present invention.
19A to 19B are views referred to explain power optimization of a solar photovoltaic system according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The suffix " module " and " part " for components used in the following description are given merely for convenience of description, and do not give special significance or role in themselves. Accordingly, the terms " module " and " part " may be used interchangeably.

FIG. 1 is a front view of a solar module according to an embodiment of the present invention, FIG. 2 is a rear view of the solar module of FIG. 1, and FIG. 3 is an exploded perspective view of the solar module of FIG.

1 to 3, a solar module 50 according to an embodiment of the present invention includes a solar cell module 100 and a junction box 200 located on one side of the solar cell module 100 . The solar module 50 may further include a heat dissipating member (not shown) disposed between the solar cell module 100 and the junction box 200.

First, the solar cell module 100 may include a plurality of solar cells 130. The first sealing material 120 and the second sealing material 150 located on the lower surface and the upper surface of the plurality of solar cells 130 and the rear substrate 110 and the second sealing material 120 located on the lower surfaces of the first sealing material 120, And may further include a front substrate 160 positioned on the top surface of the sealing member 150.

First, the solar cell 130 is a semiconductor device that converts solar energy into electrical energy. The solar cell 130 includes a silicon solar cell, a compound semiconductor solar cell, A tandem solar cell, a dye-sensitized solar cell, or a CdTe or CIGS type solar cell.

The solar cell 130 is formed of a light receiving surface on which solar light is incident and a rear surface opposite to the light receiving surface. For example, the solar cell 130 includes a silicon substrate of a first conductivity type, a second conductivity type semiconductor layer formed on the silicon substrate and having a conductivity type opposite to that of the first conductivity type, An antireflection film formed on the second conductive type semiconductor layer and having at least one opening exposing a part of the surface of the second conductive type semiconductor layer; And a rear electrode formed on the rear surface of the silicon substrate.

Each solar cell 130 may be electrically connected in series, parallel, or series-parallel. Specifically, a plurality of solar cells 130 can be electrically connected by a ribbon 133. [ The ribbon 133 may be bonded to the front electrode formed on the light receiving surface of the solar cell 130 and the rear electrode collecting electrode formed on the rear surface of another adjacent solar cell 130. [

In the figure, it is illustrated that the ribbon 133 is formed in two lines, and the solar cell 130 is connected in series by the ribbon 133 to form the solar cell string 140. By this, six strings 140a, 140b, 140c, 140d, 140e and 140f are formed, and each string includes ten solar cells. Unlike the drawings, various modifications are possible.

On the other hand, each solar cell string can be electrically connected by a bus ribbon. 1 shows a first solar cell string 140a and a second solar cell string 140b respectively formed by bus ribbons 145a, 145c and 145e disposed under the solar cell module 100, The battery string 140c and the fourth solar cell string 140d illustrate that the fifth solar cell string 140e and the sixth solar cell string 140f are electrically connected. 1 shows the second solar cell string 140b and the third solar cell string 140c respectively by the bus ribbons 145b and 145d disposed on the top of the solar cell module 100, And that the battery string 140d and the fifth solar cell string 140e are electrically connected.

On the other hand, the ribbon connected to the first string, the bus ribbons 145b and 145d, and the ribbon connected to the fourth string are electrically connected to the first through fourth conductive lines 135a, 135b, 135c, and 135d, respectively The first to fourth conductive lines 135a to 135d are connected to the bypass diodes Da, Db, and Dc in the junction box 200 disposed on the back surface of the solar cell module 100. In the drawing, the first through fourth conductive lines 135a, 135b, 135c, and 135d extend through the openings formed on the solar cell module 100 to the back surface of the solar cell module 100. FIG.

It is preferable that the junction box 200 is disposed closer to an end of the solar cell module 100 where the conductive lines extend.

1 and 2, since the first to fourth conductive lines 135a, 135b, 135c, and 135d extend from the top of the solar cell module 100 to the back surface of the solar cell module 100, ) Is located at the upper part of the back surface of the solar cell module 100. FIG. Thereby, the length of the conductive line can be reduced, and the power loss can be reduced.

1 and 2, when the first to fourth conductive lines 135a, 135b, 135c, and 135d extend from the bottom of the solar cell module 100 to the back surface of the solar cell module 100, The solar cell module 200 may be positioned at the lower part of the back surface of the solar cell module 100.

The back substrate 110 may be, but is not limited to, a TPT (Tedlar / PET / Tedlar) type having a waterproof, insulating and ultraviolet shielding function as a back sheet. 3, the rear substrate 110 may be formed in various shapes such as a circular shape or a semicircular shape depending on the environment in which the solar cell module 100 is installed.

The first sealing member 120 may be attached to the rear substrate 110 to have the same size as the rear substrate 110 and a plurality of solar cells 130 may be formed on the first sealing member 120 And can be positioned adjacent to each other so as to achieve the same.

The second sealing member 150 may be positioned on the solar cell 130 and may be laminated to the first sealing member 120.

Here, the first sealant 120 and the second sealant 150 allow each element of the solar cell to chemically bond. The first sealing material 120 and the second sealing material 150 can be various examples such as an ethylene vinyl acetate (EVA) film.

On the other hand, the front substrate 160 is preferably placed on the second sealing material 150 so as to transmit sunlight, and is preferably made of tempered glass in order to protect the solar cell 130 from an external impact or the like. Further, it is more preferable to use a low-iron-content tempered glass containing a small amount of iron in order to prevent the reflection of sunlight and increase the transmittance of sunlight.

The junction box 200 is mounted on the back surface of the solar cell module 100 and can be power-converted using the DC power supplied from the solar cell module 100. Specifically, the junction box 200 may include a capacitor portion (520 in FIG. 7) for storing DC power. Further, the junction box 200 may further include a converter (530 in Fig. 7) for level-converting and outputting a DC power source. In addition, the junction box 200 may further include bypass diodes (Da, Db, Dc) that prevent the current between the solar cell strings from flowing backward. Further, it may further include an inverter (540 in Fig. 7) for converting the direct current power into the alternating current power. This will be described later with reference to FIG.

Thus, the junction box 200 according to the embodiment of the present invention includes at least bypass diodes Da, Db, and Dc, a capacitor unit 520 (FIG. 7) 530).

When the junction box 200 is formed integrally with the solar cell module 100, the loss of the DC power generated in each solar cell module 100 is minimized as in the solar cell system shown in FIG. 17 or FIG. So that it can be efficiently managed. On the other hand, the junction box 200 integrally formed can be called a MIC (Module Integrated Converter) circuit.

On the other hand, in order to prevent moisture penetration of the circuit elements in the junction box 200, a coating for preventing moisture permeation may be performed using silicon or the like inside the junction box.

An opening (not shown) is formed in the junction box 200 so that the first to fourth conductive lines 135a, 135b, 135c and 135d are connected to the bypass diodes Da, Db and Dc in the junction box Can be connected.

On the other hand, during operation of the junction box 200, high heat is generated from the bypass diodes Da, Db, and Dc, and the generated heat is transmitted to the specific solar cell 130 Can be reduced.

In order to prevent this, the solar module 50 according to the embodiment of the present invention may further include a heat dissipating member (not shown) disposed between the solar cell module 100 and the junction box 200. In order to disperse the heat generated in the junction box 200, the cross sectional area of the heat dissipating member (not shown) is preferably larger than the cross sectional area of the plate (not shown). For example, on the entire rear surface of the solar cell module 100. The heat dissipating member (not shown) is preferably formed of a metal material such as gold (Au), silver (Ag), copper (Cu), aluminum (Al), tungsten (W) or the like with good thermal conductivity.

On the other hand, an external connection terminal (not shown) for outputting a power-converted DC power or an AC power to the outside may be formed on one side of the junction box 160.

4 is an example of a bypass diode configuration of the solar module of FIG.

Referring to the drawings, bypass diodes Da, Db, and Dc may be connected corresponding to six solar cell strings 140a, 140b, 140c, 140d, 140e, and 140f. Specifically, the first bypass diode Da is connected between the first solar cell string and the first bus ribbon 145a, and is connected to the first solar cell string 140a or the second solar cell string 140b When the reverse voltage is generated, the first solar cell string 140a and the second solar cell string 140b are bypassed.

For example, when a voltage of approximately 0.6 V generated in a normal solar cell is generated, the potential of the cathode electrode is approximately 12 V (= 0.6 V * 20), as compared with the potential of the anode electrode of the first bypass diode Da Lt; / RTI > That is, the first bypass diode Da operates normally, not bypass.

On the other hand, when a hot spot occurs due to shading or foreign matter adhering to any solar cell of the first solar cell string 140a, the voltage generated in any one solar cell is approximately 0.6V (About -15 V), rather than a voltage of about < / RTI > Accordingly, the potential of the anode electrode of the first bypass diode Da becomes higher by about 15 V than that of the cathode electrode. Accordingly, the first bypass diode Da performs the bypass operation. Therefore, the voltage generated in the solar cell in the first solar cell string 140a and the second solar cell string 140b is not supplied to the junction box 200. [ In this way, when a reverse voltage generated in some solar cells is generated, it is possible to prevent destruction of the solar cell or the like by bypassing. In addition, except for the hotspot area, it is possible to supply the generated DC power.

Next, the second bypass diode Db is connected between the first bus ribbon 145a and the second bus ribbon 145b, and is connected to the third solar cell string 140c or the fourth solar cell string 140d When the reverse voltage is generated, the third solar cell string 140c and the fourth solar cell string 140d are bypassed.

Next, the third bypass diode Dc is connected between the first solar cell string and the first bus ribbon 145a, and is connected to the first solar cell string 140a or the second solar cell string 140b When the voltage is generated, the first solar cell string and the second solar cell string are bypassed.

4, unlike FIG. 4, six bypass diodes can be connected corresponding to six solar cell strings, and various other modifications are possible.

FIG. 5 illustrates a voltage vs. current curve of the solar module of FIG. 1, and FIG. 6 illustrates a voltage versus power curve of the solar module of FIG.

Referring to FIG. 5, as the open-circuit voltage Voc supplied from the solar cell module 100 increases, the short current supplied from the solar cell module 100 becomes smaller. According to the voltage-current curve L, the voltage Voc is stored in the capacitor unit 520 provided in the junction box 200.

Referring to FIG. 6, the maximum power Pmpp supplied from the solar cell module 100 may be calculated by a maximum power point tracking algorithm (MPPT). For example, while the open-circuit voltage Voc is decreased from the maximum voltage V1, power is calculated for each voltage, and it is determined whether the calculated power is the maximum power. Since the power increases from the voltage V1 to the voltage Vmpp, the calculated power is updated and stored. Then, the power decreases from the voltage Vmpp to the voltage V2, so that Pmpp corresponding to the voltage Vmpp is determined as the maximum power.

As described above, when hot spots do not occur, only one inflection point occurs in the voltage power curve L. Therefore, the maximum power can be easily calculated only by exploring the V2 section in the V1 section.

FIG. 7 is an example of an internal circuit diagram of the power conversion apparatus according to the embodiment of the present invention, FIG. 8 is a simplified block diagram of the power conversion apparatus of FIG. 7, Figs. 10A to 10D are diagrams for explaining the operation of the switching unit and the converter in the power conversion apparatus of Fig. 7, and Fig. 11 to Fig. 13 are diagrams for explaining the power conversion And is a drawing referred to for explaining the operation of the apparatus.

7, a power conversion apparatus 700 according to an embodiment of the present invention includes a bypass diode 510, a capacitor 520, a converter 530, an inverter 540, a controller 550 ), A filter unit 560, and a switching unit 570.

The power conversion apparatus 700 receives the direct current power, converts the direct current power, and outputs the alternating current power. Particularly, according to the embodiment of the present invention, the power conversion apparatus 700 receives the DC power generated by the solar cell module 100, converts the DC power, and outputs the AC power.

The power inverter 700 can be called a micro inverter since an AC power output is possible. On the other hand, the power conversion apparatus 700 can be mounted in the junction box 200 of FIG. 2 as described above. That is, it is possible to integrally attach to the back surface of the solar cell module 100.

The bypass diode section 510 is connected to the first to fourth conductive lines 135a, 135b, 135c and 135d arranged between the respective angles of the a-node, b-node, c- And third bypass diodes Da, Db, and Dc.

The capacitor unit 520 stores the DC power supplied from the solar cell module 100. Although three capacitors Ca, Cb and Cc are connected in parallel in the figure, they may be connected in series or in series-parallel combination. It is also possible that the number thereof is variable.

The switching unit 570 switches the DC power stored in the capacitor unit 520 and selectively outputs the DC power. To this end, the switching unit 570 may include a second switching device S2 and a diode D2. When the second switching device S2 is turned on, the DC power stored in the capacitor 520 is transferred to the converter 530. When the second switching device S2 is not turned off, the capacitor 520 Is not transmitted to the converter 530. [0050]

In accordance with the operation of the switching unit 570, the converter 530 operates in a boost mode or operates in a buck mode. This will be described later.

The converter 530 performs the level conversion using the DC power supplied from the switching unit 570. In the embodiment of the present invention, a tapped inductor boost converter is connected to the converter 530 so as to boost the DC power supplied from the solar cell module 100 and output a DC power having a higher level. For example. Compared to a boost converter or a flyback converter, a tap inductor boost converter can output a low voltage with high efficiency and high voltage.

Particularly, when a tap inductor boost converter is used for a solar cell module 100 that has about 50 to 60 solar cells and outputs a DC power of about 30 to 50 V, a high-voltage output voltage (about 300 V or more) Can be efficiently output.

Accordingly, the converter 530 includes a tap inductor T, a first switching device S1 that is connected between the tap inductor T and the ground terminal, a diode connected to the output terminal of the tap inductor and performing one- D1). Meanwhile, a capacitor C1 may be further provided between the output terminal of the diode D1, that is, between the cathode and the ground, for storing output power.

Specifically, the first switching device S1 may be connected between the taps of the tap inductor T and the ground terminal. The output terminal (secondary side) of the tap inductor T is connected to the anode of the diode D1 and the capacitor C1 is connected between the cathode terminal of the diode D1 and the ground terminal of the diode D1.

On the other hand, the primary side and the secondary side of the tap inductor T have opposite polarities. On the other hand, the tap inductor T may be referred to as a switching transformer.

The inverter 540 converts the level-converted DC power from the converter 530 to AC power. In the drawing, a full-bridge inverter is illustrated. Namely, the upper and lower arm switching elements Sa and Sb connected in series to each other and the lower arm switching elements S'a and S'b are paired, and two pairs of upper and lower arm switching elements are connected in parallel to each other (Sa & Sb & S'b). Diodes are connected in anti-parallel to each switching element Sa, S'a, Sb, S'b.

The switching elements in the inverter 540 are turned on / off based on the inverter switching control signal from the controller 550. [ As a result, AC power having a predetermined frequency is output. Preferably, it has a frequency (approximately 60 Hz or 50 Hz) that is equal to the alternating frequency of the grid.

The filter unit 560 performs smooth understanding of the AC power output from the inverter 540 and performs low pass filtering. To this end, in the figure, the inductors Lf1 and Lf2 are exemplified, but various examples are possible.

The input current sensing unit A senses an input current ic1 input to the converter 530. The input voltage sensing unit B senses an input voltage vc1 input to the converter 530 do. The sensed input current ic1 and the input voltage vc1 may be input to the control unit 550. [

The output current sensing unit C senses the output current ic2 output from the converter 530 and the output voltage sensing unit B senses the output voltage vc2 output from the converter 530 do. The sensed output current ic2 and the output voltage vc2 may be input to the control unit 550. [

Meanwhile, the control unit 550 may output a control signal for controlling the second switching device S2 of the switching unit 570 of FIG. In particular, the control unit 550 controls the first switching device 530 in the converter 530 based on at least one of the sensed input current ic1, the input voltage vc1, the output current ic2, or the output voltage vc2. The turn-on timing signal of the switch S1 can be outputted.

On the other hand, the control unit 550 can output a control signal for controlling the first switching device S1 of the converter 530 in Fig. In particular, the control unit 550 controls the switching unit 570 based on at least one of the sensed input current ic1, the input voltage vc1, the output current ic2, or the output voltage vc2. It is possible to output the turn-on timing signal of the element S2.

On the other hand, the control unit 550 may output an inverter control signal for controlling each of the switching elements Sa, S'a, Sb, S'b of the inverter 540. In particular, the control unit 550 controls each switching element of the inverter 540 based on at least one of the sensed input current ic1, the input voltage vc1, the output current ic2 or the output voltage vc2. Sa, S'a, Sb, S'b).

On the other hand, the control unit 550 can control the converter 530 to calculate the maximum power point for the solar cell module 100 and accordingly output the DC power corresponding to the maximum power.

8, the converter 530 of the power conversion apparatus 700 according to the embodiment of the present invention converts the DC power from the solar cell module 100 into a pseudo DC voltage can do.

The DC power supply output from the converter 530 by controlling the switching on / off of the first switching element S1 is controlled by a DC power supply having a constant level and having an envelope like a half-wave rectified DC power supply, It can be converted into a pseudo dc voltage. Accordingly, the pseudo DC power can be stored in the capacitor C1.

Meanwhile, the inverter 540 receives a pseudo DC voltage, performs a switching operation, and outputs the AC power.

On the other hand, when the pseudo direct current power source is output using the tap inductor boost converter 530 without the switching unit 570 in Fig. 7, the pseudo direct current power source Vcf is supplied with the half-wave rectified direct current power And has an offset according to the input power supply Vpv. That is, a constant voltage maintaining period corresponding to the input power supply Vpv is generated. As a result, a desired output AC power source waveform can not be obtained, the output current quality deteriorates, and in particular, the influence of the harmonic current component can be increased.

In the embodiment of the present invention, in order to prevent this, the operation mode (MODE 1, MODE 2) is distinguished from the constant voltage maintaining period of the DC power outputted from the converter 530 and the other section, So that the switching unit 570 is operated.

In particular, the control unit 550 determines whether or not the DC power source Vc2 sensed by the output voltage sensing unit B maintains the constant voltage and, if so, the switching unit 570 ). If not, the control unit 550 controls the switching unit 570 to operate in the second power conversion mode.

When the converter 530 and the inverter 540 are operated in the first power conversion mode and the second power conversion mode, an output AC power source waveform that falls to the ground voltage can be obtained as shown in FIG. 9A. That is, a desired output AC power source waveform can be obtained, and the output current quality is improved. Particularly, the influence of the harmonic current component can be reduced.

Hereinafter, the operation of the first power conversion mode and the second power conversion mode will be described with reference to Figs. 10A to 13.

10A to 10D are diagrams referred to explain the operation of the switching unit 570 and the tap inductor boost converter 530. In FIG.

10A and 10B illustrate a case where the second switching element S2 of the switching unit 560 is turned on and FIGS. 10C and 10D illustrate a case where the second switching element S2 of the switching unit 560 is turned on. Is turned off. When the second switching element S2 is turned on, the first diode D2 is turned off, and when the second switching element S2 is turned off, conduction is unidirectional.

When the first switching device S1 in the converter 530 is turned on with the second switching device S2 of the switching unit 560 turned on, A closed loop is formed through the voltage Vpv, the second switching element S2, the primary side of the tapped inductor T and the first switching element S1, and the first current I1 flows through the closed And flows on the loop. At this time, since the secondary side of the tap inductor T has the opposite polarity to the primary side, the diode D1 can not be turned on and is turned off. As a result, the energy due to the input voltage Ppv is stored in the primary side of the tapped inductor T. [

Next, when the first switching device S1 in the converter 530 is turned off in the state that the second switching device S2 of the switching unit 560 is turned on, A closed loop is formed through the input voltage Vpv, the second switching element S2, the primary side and the secondary side of the tap inductor T and the diode D1 and the capacitor C1, The second current I2 flows on the closed loop. That is, since the secondary side of the tap inductor T has the opposite polarity to the primary side, the diode D1 becomes conductive. Accordingly, the input voltage Ppv, the energy stored in the primary side and the secondary side of the tap inductor T can be stored in the capacitor C1 via the diode D1.

As described above, the converter 530 can output a high-efficiency and high-voltage direct-current power by using the input voltage Ppv, the energy stored in the primary side and the secondary side of the tapped inductor T. [ Accordingly, when the second switching device S2 of the switching unit 560 is turned on, the converter 530 can operate in a boost mode.

Next, when the first switching device S1 in the converter 530 is turned on with the second switching device S2 of the switching unit 560 turned off, the tap inductor T The second diode D2 of the switching unit 570 conducts in one direction as shown in FIG. 10C because of the energy stored in the primary side of the switching unit 570. FIG. Thereby, a closed loop is formed through the second diode D2, the primary side of the tapped inductor T, and the first switching device S1, and the third current I3 flows through the closed loop Flow. At this time, since the secondary side of the tap inductor T has the opposite polarity to the primary side, the diode D1 can not be turned on and is turned off. As a result, the energy stored in the primary side of the tap inductor T is consumed through the closed loop.

Next, when the first switching device S1 in the converter 530 is turned off in a state where the second switching device S2 of the switching unit 560 is turned off, , And the second diode D2 of the switching unit 570 conducts in one direction. Thereby, a closed loop through the primary diode, the secondary side, and the diode D1 and the capacitor C1 of the second diode D2, the second switching device S2, the tap inductor T, And the second current I2 flows on the closed loop. That is, since the secondary side of the tap inductor T has the opposite polarity to the primary side, the diode D1 becomes conductive. Accordingly, the energy stored in the primary side and the secondary side of the tap inductor T can be stored in the capacitor C1 via the diode D1.

At this time, since the energy stored in the primary side of the tap inductor T is reduced as described with reference to FIG. 10C, the energy stored in the secondary side is also reduced. As a result, the voltage stored in the capacitor C1 d is lowered Is stored. Accordingly, when the second switching device S2 of the switching unit 560 is turned off, the converter 530 may operate in a buck mode.

In the embodiment of the present invention, the converter 530 is operated in the buck mode with respect to the constant voltage maintaining period of the DC power outputted from the converter 530. [ And operate in the boost mode in the other sections.

Fig. 11 is a simplified circuit diagram of the power conversion apparatus of Fig. 7, Fig. 12 illustrates a waveform diagram of a switching element in a converter and an inverter, Fig. 13 shows a waveform diagram of a final output Output AC power source waveform.

The control unit 550 controls the switching unit 560 such that the constant voltage maintaining period corresponding to the input power source Vpv among the pseudo direct current power outputted from the converter 530 occurs in the first power conversion mode (MODE 1) The second switching element S2 can be controlled to be turned off.

Also, the control unit 550 can control the first switching device S1 in the converter 530 to perform high-speed switching during the first power conversion mode (MODE 1) as shown in FIG. For example, it can be controlled to perform high-speed switching at a frequency of 100 kHz.

As a result, the converter 530 operates in a buck mode, so that the DC power source in the constant voltage holding period falls to the ground power source of 0V, as shown in FIG. 9A. Therefore, the current quality of the output current outputted from the inverter 540 can be improved. In addition, the harmonic current component is significantly reduced.

12, the control unit 550 may control the first switching device S1 in the converter 530 to switch at low speed during the first power conversion mode (MODE 1) period. In particular, a pulse width modulation (PWM) based switching operation can be performed to output a pseudo direct current power.

Next, the control unit 550 can control the second switching element S2 of the switching unit 560 to be turned on as the second power conversion mode (MODE 2) in a period in which the constant voltage maintaining period does not occur .

In addition, the control unit 550 can control the first switching device S1 in the converter 530 to perform low-speed switching during the second power conversion mode (MODE 2) period. In particular, a pulse width modulation (PWM) based switching operation can be performed to output a pseudo direct current power.

As a result, the converter 530 operates in a boost mode, thereby outputting the voltage waveform corresponding to the pseudo direct current power source in the section excluding the constant voltage maintenance section as shown in FIG. 9A.

As a result, the output voltage waveform in the first power conversion mode (MODE 1 (a), MODE 1 (b)) and the output voltage waveform in the second power conversion mode (MODE 2) The output voltage Vout, as shown in Fig. 9A, can be output from the power inverter 700. [

On the other hand, the output AC power source waveform as shown in FIG. 9A or FIG. 13 is low-pass filtered through the filter unit 560 in FIG. 11, and is output as a smooth AC power source waveform.

Each of the switching elements Sa, S'a, Sb and S'b in the inverter 540 has a constant switching frequency regardless of the first power conversion mode (MODE 1) and the second power conversion mode (MODE 2) The switching operation can be performed. For example, switching operation can be performed at a low frequency of 100 Hz or 120 Hz.

On the other hand, Fig. 14 is similar to Fig. 7, except that two tap inductor boost converters 530a and 530b are used.

14 includes a capacitor unit 520, two tap inductor boost converters 530a and 530b, an inverter 540, a filter unit 560, and a switching unit 570 can do.

When the two tap inductor boost converters 530a and 530b are connected in parallel to each other as shown in the figure, that is, when an interleaving method is used, the capacitive part 520 and the switching part 570 The ripple of the current component output through each of the converters 530a and 530b is reduced. Accordingly, the reliability of the capacitor provided in the capacitor unit 520 can be secured.

On the other hand, Fig. 15 is similar to Fig. 7 except that three tap inductor boost converters 530a, 530b, and 530c are used.

14 includes a capacitor unit 520, three tap inductor boost converters 530a, 530b, and 530c, an inverter 540, a filter unit 560, and a switching unit 570 ).

At this time, the element characteristics of the tapped inductor and the switching element in each of the converters 530a, 530b, and 530c may be the same.

On the other hand, when the three tap inductor boost converters 530a and 530b are connected in parallel to each other as shown in the figure, that is, when the interleaving method is used, the capacitor unit 520 and the switching unit 570 , The current components to be delivered are branched in parallel so that the ripple of the current component output through each of the converters 530a, 530b, and 530c is reduced. Accordingly, the reliability of the capacitor provided in the capacitor unit 520 can be secured.

On the other hand, each of the converters 530a, 530b, and 530c can adaptively operate in accordance with the power required value of the AC power to be output.

For example, if only the first converter 530a is operating, or if the power requirement is approximately 200W, only the first and second converters 530a and 530b operate, or the power requirement is approximately 300W , All of the first to third converters 530a, 530b, and 530c can operate.

On the other hand, when at least two of the first to third converters 530a, 530b, and 530c operate, the turn-on / turn-off timings of the respective switching elements may be the same.

16 illustrates an internal circuit diagram of a junction box of the solar module of Fig.

16, a junction box 200 according to an embodiment of the present invention includes a bypass diode 510, a capacitor 520, a converter 530, a controller 550, and a switching unit 570, . ≪ / RTI > That is, the inverter 540 and the filter unit 560 of the power inverter 700 of FIG. 7 are not included. The inverter 540 and the filter unit 540, which are not included in the junction box 200, may be provided separately.

Accordingly, the junction box 200 of FIG. 16 can output DC power. In this case, when the junction box 200 performs a power optimizing function, the junction box 200 may be referred to as a power optimizer.

As shown in FIG. 16, the DC power source can be easily supplied through the junction box by including the capacitor unit for storing the DC power source in the junction box and the converter for level-converting the stored DC power source. In addition, it is easy to install the solar module, and it is advantageous to expand the capacity of the solar system including a plurality of solar modules and the system configuration.

7 and FIG. 16, the junction box 200 may include only the bypass diode 510 and the capacitor 520. Accordingly, the converter 530, the inverter 540, and the filter unit 560 may be separately disposed outside the junction box 200.

17 is an example of a configuration diagram of a solar photovoltaic system according to an embodiment of the present invention.

Referring to the drawings, the solar photovoltaic system of Fig. 17 includes a plurality of solar modules 50a, 50b, ..., 50n. Each solar module 50a, 50b, ..., 50n may include junction boxes 200a, 200b, ..., 200n for outputting AC power. The junction boxes 200a, 200b, ..., 200n may be referred to as junction boxes having microinverters. The alternating current power output from the junction boxes 200a, 200b, ..., as shown in FIG.

7 may be implemented in the junction box 200 and the internal circuit of the junction box 200 may be applied to the microinverter of FIG. 17 .

7, the junction box 200a, 200b, ..., 200n includes a bypass diode unit 510, a capacitor unit 520, a converter 530, an inverter 540 control unit 550, And a filter unit 560. In particular, converter 530 may be a tap inductor boost converter 530, including a tap inductor and a switching element, as in FIG.

FIG. 18 is another example of the configuration diagram of the solar photovoltaic system according to the embodiment of the present invention.

Referring to the drawings, the solar photovoltaic system of Fig. 18 includes a plurality of solar modules 50a, 50b, ..., 50n. Each solar module 50a, 50b, ..., 50n may include junction boxes 1200a, 1200b, ..., 1200n for outputting DC power. Further, a separate inverter 1210 for converting the direct current power outputted from each of the solar modules 50a, 50b, ..., 50n to the alternating current power source is further provided. At this time, the junction boxes 1200a, 1200b, ..., 1200n may be junction boxes having power optimizers for efficiently outputting DC power.

Meanwhile, the internal circuit of the junction box 200 of FIG. 16 according to the embodiment of the present invention can be applied to the power optimizer of FIG.

In other words, each of the junction boxes 200a, 200b, ..., 200n includes a bypass diode unit 510, a capacitor unit 520, a converter 530, and a control unit 550 . In particular, converter 530 may be a tap inductor boost converter 530, including a tap inductor and a switching element, as in FIG.

19A to 19B are views referred to explain power optimization of a solar photovoltaic system according to an embodiment of the present invention.

First, referring to FIG. 19A, a case where power optimizing is not applied will be described. In the case where a plurality of solar cell modules are connected in series as shown in the drawing, when hot spots are generated in some solar cell modules 1320 and some power loss occurs (for example, 70W power supply) A normal solar cell module 1310 also causes some power loss (for example, 70W power supply). Therefore, only 980W of power is supplied in total.

Next, referring to Fig. 19B, a case where power optimizing is applied will be described. When a hot spot occurs in some solar cell modules 1320 and some power loss occurs (for example, 70W power supply), the current supplied from the corresponding solar cell module 1320 is supplied to another solar cell module 1310, The voltage output from the solar cell module 1320 is lowered so as to be equal to the current supplied from the solar cell module 1320. [ Accordingly, in the solar cell module 1320 in which the hot spot has occurred, some power loss occurs (for example, 70W power supply), but in the normal solar cell module 1310, Power supply). Therefore, a total power of 1340 W can be supplied.

As described above, according to the power optimizing, the voltage supplied from the solar cell module in which the hot spot occurs can be adjusted in accordance with the current supplied from another solar cell module. To this end, each solar cell module receives a current value or a voltage value supplied from another solar cell module, and can control a voltage output in the solar cell module.

On the other hand, the junction box 200 of FIG. 16 according to the embodiment of the present invention can be applied to the power optimizer of FIG. 19B.

The power conversion apparatus or the solar module according to the present invention is not limited in the configuration and the method of the embodiments described above but the embodiments can be applied to all or some of the embodiments May be selectively combined.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention.

Claims (20)

A switching unit provided with a switching element, for switching and selectively outputting an input DC power;
A converter having a tap inductor and a switching element, the converter converting the DC power from the switching unit to a level; And
And an inverter that has a plurality of switching elements and converts the level-converted DC power into an AC power,
During the turn-off period of the switching element of the switching unit, the converter operates in a first power conversion mode,
During the turn-on period of the switching element of the switching unit, the converter operates in a second power conversion mode,
Wherein the switching frequency of the switching element in the converter during the first power mode conversion mode is higher than the switching frequency of the switching element in the converter during the second power mode conversion mode,
And an output AC power source that falls to a ground voltage is output during the first power mode conversion mode. The method according to claim 1,
Wherein the first power conversion mode is a buck mode,
And the second power conversion mode is a boost mode. delete The method according to claim 1,
The converter includes:
And converts the level of the direct current power to a level converted pseudo direct current power. The method according to claim 1 or 4,
And a filter unit that low-pass filters the AC power output from the inverter. The method according to claim 1,
Wherein the first power conversion mode section corresponds to a constant voltage maintenance section of the DC power source converted by the converter. The method according to claim 1,
The power conversion apparatus includes:
And a plurality of converters each having a tapped inductor and a switching element and connected in parallel to each other. 8. The method of claim 7,
Wherein at least a part of the plurality of converters operates in response to a power required value of the AC power outputted. The method according to claim 1,
And a control unit for controlling a switching operation of the switching unit of the switching unit, the switching device of the converter, and the switching devices of the inverter. A solar cell module comprising a plurality of solar cells; And
And a power conversion unit converting the DC power supplied from the solar cell module and converting the DC power into an AC power,
Wherein the power conversion unit comprises:
A switching unit provided with a switching element, for switching and selectively outputting an input DC power;
A converter having a tap inductor and a switching element, the converter converting the DC power from the switching unit to a level; And
And an inverter that has a plurality of switching elements and converts the level-converted DC power into an AC power,
During the turn-off period of the switching element of the switching unit, the converter operates in a first power conversion mode,
During the turn-on period of the switching element of the switching unit, the converter operates in a second power conversion mode,
Wherein the switching frequency of the switching element in the converter during the first power mode conversion mode is higher than the switching frequency of the switching element in the converter during the second power mode conversion mode,
And an output AC power source that falls to a ground voltage is output during the first power mode conversion mode. 11. The method of claim 10,
Wherein the first power conversion mode is a buck mode,
Wherein the second power conversion mode is a boost mode. delete 11. The method of claim 10,
The converter includes:
Converts the level of the direct current power to a level-converted pseudo direct current power. 14. The method according to claim 10 or 13,
Wherein the power conversion unit comprises:
And a filter unit that low-pass filters the AC power output from the inverter. 11. The method of claim 10,
Wherein the first power conversion mode section corresponds to a constant voltage maintenance section of the DC power source that is converted by the converter. 11. The method of claim 10,
Wherein the power conversion unit comprises:
A plurality of converters having a tapped inductor and a switching element and connected in parallel to each other,
Wherein at least a part of the plurality of converters operates in response to a power required value of the AC power outputted from the power conversion unit. 11. The method of claim 10,
Wherein the power conversion unit comprises:
And a control unit for controlling a switching operation of the switching unit of the switching unit, the switching device of the converter, and the switching devices of the inverter. 11. The method of claim 10,
Wherein the power conversion unit comprises:
And a bypass diode for bypassing a solar cell generating a reverse voltage among the plurality of solar cells. 11. The method of claim 10,
The converter and the inverter in the power conversion unit are mounted in a junction box,
Wherein the junction box is attached to the solar cell module and is integrally formed. 11. The method of claim 10,
The converter in the power conversion section is mounted in a junction box,
Wherein the junction box is attached to the solar cell module and is integrally formed.

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