KR20140010218A - Power converting apparatus, and photovoltaic module - Google Patents

Abstract

The present invention relates to a power conversion device and a sunlight module. The power conversion device according to the embodiment of the present invention comprises a switching unit which has a switching element and switches the inputted direct current power to be selectively outputted; a converter which has a tab inductor and a switching element and level converts the direct current power from the switching unit to be outputted; and an inverter which has a plurality of switching elements and converts the level converted direct current power to an alternating current power, wherein the converter operates in a first power conversion mode during the turn-off section of the switching element in the switching unit while operating in a second power conversion mode during the turn-on section of the switching element in the switching unit, thereby improving the output current quality. [Reference numerals] (550) Control unit

Description

Power converting apparatus, and photovoltaic module

The present invention relates to a power converter, and a solar module, and more particularly, to a power converter that can improve the output current quality, and a solar module.

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 spotlighted as next-generation cells that directly convert solar energy into electrical energy using semiconductor devices.

On the other hand, the photovoltaic module refers to a state in which solar cells for photovoltaic power generation are connected in series or in parallel, and the photovoltaic module may include a junction box for collecting electricity produced by the solar cells.

An object of the present invention is to provide a power converter and a solar module that can improve the output current quality.

Power conversion apparatus according to an embodiment of the present invention for achieving the above object, the switching unit having a switching element for switching the DC power input and selectively output, and having a tap inductor and a switching element from the switching unit And a converter for level converting and outputting the DC power, and an inverter having a plurality of switching elements and converting the level converted DC power to AC power, wherein the converter converts the first power during the turn-off period of the switching element of the switching unit. Mode, the converter operates in the second power conversion mode during the turn-on period of the switching element of the switching unit.

In addition, the solar module according to an embodiment of the present invention for achieving the above object, the solar cell module having a plurality of solar cells, and power conversion to convert the DC power supplied from the solar cell module to convert to AC power And a power converter including a switching element for switching the DC power input and selectively outputting the switching power supply, and a converter having a tap inductor and a switching element for level converting and outputting the DC power from the switching device. And an inverter for converting a level-converted DC power source into an AC power source, 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, the converter operates in the second power conversion mode.

According to an embodiment of the present invention, according to the turning on or off of the switching element of the switching unit in the power converter or the photovoltaic module, the converter connected to the switching unit is divided into the boost mode or the buck mode to operate the output current Quality can be improved.

In particular, when the converter outputs a pseudo DC power supply and a constant voltage holding section occurs, the desired output AC power waveform can be obtained by lowering the constant voltage to the ground voltage, thereby improving output current quality. In particular, the influence of the harmonic current component can be reduced.

The ripple of the current component output from the converter is reduced, thus ensuring the reliability of the capacitor disposed in front of the converter.

On the other hand, the power converter or the solar module, by providing a tap inductor boost converter, it is possible to ensure a high-efficiency high voltage DC power supply.

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

Meanwhile, the power converter or the solar module may include a plurality of tap inductor boost converters which are connected in parallel to each other, and each converter is capable of adaptive operation according to power requirements, thereby improving 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. 1.
4 is an example of a bypass diode configuration of the solar module of FIG. 1.
5 illustrates a voltage versus current curve of the solar module of FIG. 1.
6 illustrates a voltage versus power curve of the solar module of FIG. 1.
7 is an example of an internal circuit diagram of a power conversion apparatus according to an embodiment of the present invention.
FIG. 8 is a simplified block diagram of the power converter of FIG. 7.
9A to 9B illustrate examples and comparative examples of output currents output from the power converter of FIG. 7.
10A through 10D are views for explaining the operation of the switching unit and the converter in the power converter of FIG. 7.
11 to 13 are views for explaining the operation of the power converter of FIG.
14 is another example of an internal circuit diagram of a power conversion apparatus according to an embodiment of the present invention.
15 is another example of an internal circuit diagram of a power converter according to an embodiment of the present invention.
FIG. 16 illustrates an internal circuit diagram of a junction box of the solar module of FIG. 1.
17 is an example of configuration diagram of a solar system according to an embodiment of the present invention.
18 is another example of the configuration diagram of the solar system according to the embodiment of the present invention.
19A to 19B are views referred to for describing power optimization of a solar system according to an embodiment of the present invention.

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

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.

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

1 to 3, the solar module 50 according to the embodiment of the present invention includes a solar cell module 100 and a junction box 200 located on one surface of the solar cell module 100. . In addition, the solar module 50 may further include a heat dissipation 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. In addition, the first sealing member 120 and the second sealing member 150 positioned on the lower surface and the upper surface of the plurality of solar cells 130, the rear substrate 110 and the second positioned on the lower surface of the first sealing member 120. The apparatus may further include a front substrate 160 positioned on an upper surface of the sealant 150.

First, the solar cell 130, the solar cell 130 is a semiconductor device that converts solar energy into electrical energy, such as silicon solar cells, compound semiconductor solar cells, and stacked solar cells. It may be a tandem solar cell, dye-sensitized or CdTe, CIGS-type solar cell and the like.

The solar cell 130 is formed of a light receiving surface on which sunlight is incident and a rear surface opposite to the light receiving surface. For example, the solar cell 130 includes a first conductive silicon substrate, a second conductive semiconductor layer formed on the silicon substrate and having a conductivity opposite to the first conductive type, and the second conductive semiconductor layer. An anti-reflection film formed on the second conductivity-type semiconductor layer, the at least one opening exposing at least one surface thereof, and a front electrode contacting a part of the second conductivity-type semiconductor layer exposed through the at least one opening; It may include a back electrode formed on the back of the silicon substrate.

Each solar cell 130 may be electrically connected in series or in parallel or in parallel. Specifically, the plurality of solar cells 130 may be electrically connected by the 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 current collecting electrode formed on the back surface of another adjacent solar cell 130.

In the figure, the ribbon 133 is formed in two lines, by the ribbon 133, the solar cells 130 are connected in a row, illustrating that the solar cell string 140 is formed. As a result, 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. FIG. 1 shows that the first solar cell string 140a and the second solar cell string 140b are formed by the bus ribbons 145a, 145c, and 145e disposed under the solar cell module 100, respectively. 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. In addition, in FIG. 1, the 2nd solar cell string 140b and the 3rd solar cell string 140c are respectively comprised by the bus ribbon 145b, 145d arrange | positioned on the upper part of the solar cell module 100, The 4th aspect It illustrates 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 to fourth conductive lines 135a, 135b, 135c, and 135d, respectively. 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 200 disposed on the rear surface of the solar cell module 100. In the drawings, the first to fourth conductive lines 135a, 135b, 135c, and 135d extend to the rear surface of the solar cell module 100 through openings formed on the solar cell module 100.

On the other hand, it is preferable that the junction box 200 is further disposed adjacent to an end portion of which the conductive line extends from both ends of the solar cell module 100.

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 rear surface of the solar cell module 100, the junction box 200 may be used. ) Illustrates that the solar cell module 100 is located above the back of the solar cell module 100. As a result, the length of the conductive line can be reduced, and power loss can be reduced.

Unlike FIGS. 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 rear surface of the solar cell module 100, the junction box The 200 may be located at the lower side of the rear surface of the solar cell module 100.

The back substrate 110 is a back sheet, and functions as a waterproof, insulation, and UV protection, and may be a TPT (Tedlar / PET / Tedlar) type, but is not limited thereto. In addition, although the rear substrate 110 is shown in a rectangular shape in FIG. 3, the rear substrate 110 may be manufactured in various shapes such as a circle and a semi-circle according to an environment in which the solar cell module 100 is installed.

On the other hand, the first sealing material 120 may be attached to the same size as the rear substrate 110 on the rear substrate 110, the plurality of solar cells 130 on the first sealing material 120 is a few rows. Can be located next to each other to achieve.

The second sealing material 150 may be positioned on the solar cell 130 and bonded to the first sealing material 120 by lamination.

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

On the other hand, the front substrate 160 is located on the second sealing material 150 so as to transmit sunlight, it is preferable that the tempered glass in order to protect the solar cell 130 from an external impact. 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 attached to the rear surface of the solar cell module 100 and may convert power using a DC power supplied from the solar cell module 100. Specifically, the junction box 200 may include a capacitor unit 520 of FIG. 7 that stores a DC power. In addition, the junction box 200 may further include a converter (530 of FIG. 7) that converts and outputs the level of the DC power. In addition, the junction box 200 may further include bypass diodes Da, Db, and Dc that prevent current from flowing back between the strings of the solar cells. In addition, an inverter (540 of FIG. 7) for converting DC power into AC power may be further provided. This will be described later with reference to FIG.

As described above, 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 in FIG. 7) that stores a DC power supply, and a converter (FIG. 7). 530 may be provided.

When the junction box 200 is integrally formed with the solar cell module 100, as in the solar system of FIG. 17 or 18 to be described later, the loss of DC power generated in each solar cell module 100 is minimized. It can be managed efficiently. Meanwhile, the junction box 200 integrally formed may be referred to as a module integrated converter (MIC) circuit.

Meanwhile, in order to prevent moisture penetration of circuit elements in the junction box 200, the inside of the junction box may be coated with a moisture barrier to prevent moisture penetration.

On the other hand, an opening (not shown) is formed in the junction box 200, and the first to fourth conductive lines 135a, 135b, 135c, and 135d described above are connected to the bypass diodes Da, Db, and Dc in the junction box. Can be connected.

Meanwhile, during operation of the junction box 200, high heat is generated from the bypass diodes Da, Db, and Dc, and the generated heat is generated in the specific solar cell 130 arranged at the position where the junction box 200 is attached. ) Can reduce the efficiency.

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

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

4 is an example of a bypass diode configuration of the solar module of FIG. 1.

Referring to the drawings, the bypass diodes Da, Db, and Dc may be connected to the 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, so that the first solar cell string 140a or the second solar cell string 140b is connected. 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 0.6V generated in a normal solar cell occurs, the potential of the cathode electrode is about 12V (= 0.6V * 20) relative to the potential of the anode electrode of the first bypass diode Da. Becomes higher. That is, the first bypass diode Da performs normal operation instead of bypass.

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

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

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

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

First, referring to FIG. 5, as the open voltage Voc supplied from the solar cell module 100 increases, a short current supplied from the solar cell module 100 decreases. According to the voltage current curve L, the corresponding voltage Voc is stored in the capacitor unit 520 provided in the junction box 200.

Meanwhile, 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 reducing the open voltage Voc 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. In addition, since the power decreases from the Vmpp voltage to the V2 voltage, eventually, Pmpp corresponding to the Vmpp voltage is determined as the maximum power.

As such, when no hot spot occurs, only one inflection point is generated in the voltage power curve L, so that the maximum power can be simply calculated by simply exploring the V2 section in the V1 section.

7 is an example of an internal circuit diagram of a power converter according to an embodiment of the present invention, FIG. 8 is a simplified block diagram of the power converter of FIG. 7, and FIGS. 9A to 9B are output from the power converter of FIG. 7. 10A to 10D are views for explaining the operation of a switching unit and a converter in the power converter of FIG. 7, and FIGS. 11 to 13 are power conversions of FIG. 7. Reference is made to the description of the operation of the apparatus.

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

The power converter 700 receives DC power, converts DC power, and outputs AC power. In particular, the power converter 700 according to the embodiment of the present invention receives the DC power generated by the solar cell module 100, converts the DC power, and outputs AC power.

The power converter 700 may be referred to as a micro inverter because the AC power output is possible. On the other hand, as described above, the power converter 700 may be mounted in the junction box 200 of FIG. That is, it is possible to be integrally attached to the back of the solar cell module 100.

The bypass diode unit 510 includes the first to fourth nodes disposed between the a, b, c, and d nodes corresponding to the first to fourth conductive lines 135a, 135b, 135c, and 135d, respectively. Third bypass diodes Da, Db, and Dc are included.

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

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

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

The converter 530 performs level conversion by using the DC power supplied from the switching unit 570. In an embodiment of the present invention, a tapped inductor boost converter is used as the converter 530 to boost the DC power supplied from the solar cell module 100 to output the level-improved DC power. To illustrate. The tap inductor boost converter can output a low voltage at a high efficiency and a high voltage as compared to a boost converter or a flyback converter.

In particular, for a solar cell module 100 having approximately 50 to 60 solar cells and outputting a DC power of approximately 30 to 50 V, when using a tap inductor boost converter, a high voltage output voltage (about 300 V or more) Can be output efficiently.

Accordingly, the converter 530 is connected to the tap inductor T, the first switching element S1 connected between the tap inductor T and the ground terminal, and the diode connected to the output terminal of the tap inductor to perform one-way conduction ( D1). On the other hand, a capacitor (C1) for storing the output power may be further provided between the output terminal of the diode (D1), that is, between the cathode (cathod) and the ground terminal.

In detail, the first switching device S1 may be connected between the tab 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 dhk ground terminal of the diode D1.

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

The inverter 540 converts the DC power level converted by the converter 530 into AC power. In the figure, a full-bridge inverter is illustrated. That is, the upper arm switching elements Sa and Sb and the lower arm switching elements S'a and S'b, which are connected in series with each other, become a pair, and a total of two pairs of upper and lower arm switching elements are parallel to each other (Sa & S'a, Sb & S'b). Diodes are connected in anti-parallel to each of the switching elements Sa, S'a, Sb, and S'b.

The switching elements in the inverter 540 turn on / off based on the inverter switching control signal from the controller 550. As a result, an AC power supply having a predetermined frequency is output. Preferably, it is desirable to have the same frequency (approximately 60 Hz or 50 Hz) as the alternating frequency of the grid.

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

The input current detector A detects an input current ic1 input to the converter 530, and the input voltage detector B detects an input voltage vc1 input to the converter 530. do. The detected input current ic1 and the input voltage vc1 may be input to the controller 550.

The output current detector C detects the output current ic2 output from the converter 530, and the output voltage detector B detects the output voltage vc2 output from the converter 530. do. The sensed output current ic2 and output voltage vc2 may be input to the controller 550.

The controller 550 may output a control signal for controlling the second switching element S2 of the switching unit 570 of FIG. 7. In particular, the controller 550 may include the first switching element 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 S1 may be output.

The controller 550 may output a control signal for controlling the first switching element S1 of the converter 530 of FIG. 7. In particular, the controller 550 may switch the second switch of the switching unit 570 based on at least one of the detected input current ic1, the input voltage vc1, the output current ic2, or the output voltage vc2. The turn-on timing signal of the device S2 may be output.

The controller 550 may output an inverter control signal for controlling each of the switching elements Sa, S'a, Sb, and S'b of the inverter 540. In particular, the controller 550 is configured to switch each switching element of the inverter 540 based on at least one of the detected input current ic1, the input voltage vc1, the output current ic2, or the output voltage vc2. The turn-on timing signals of Sa, S'a, Sb, and S'b) may be output.

The controller 550 may control the converter 530 to calculate the maximum power point for the solar cell module 100 and to output a DC power corresponding to the maximum power.

Meanwhile, referring to FIG. 8, the converter 530 of the power converter 700 according to the embodiment of the present invention converts a DC power source from the solar cell module 100 into a pseudo DC power source. can do.

By controlling the switching on / off of the first switching element S1, the DC power output from the converter 530 has a envelope, such as a half-wave rectified DC power, not a DC power supply having a constant level, but a pseudo direct current. It can be converted to a pseudo dc voltage. Accordingly, a pseudo DC power source may be stored in the capacitor C1.

The inverter 540 receives a pseudo DC voltage, performs a switching operation, and outputs the alternating current to an AC power source.

On the other hand, when the pseudo DC power supply is output using the tap inductor boost converter 530 of FIG. 7 without the switching unit 570, as shown in FIG. 9B, the pseudo DC power supply Vcf is a half-wave rectified DC power supply. It has an envelope (Vdc) as shown, and has an offset according to the input power (Vpv). That is, a constant voltage sustain period corresponding to the input power source Vpv occurs. As a result, the desired output AC power supply waveform cannot be obtained, the output current quality becomes poor, 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) in the constant voltage maintenance section of the DC power output from the converter 530, and other sections, and corresponds to each operation mode Thus, the switching unit 570 is operated.

In particular, the control unit 550 determines whether the DC power supply Vc2 detected by the output voltage detecting unit B maintains a constant voltage, and if applicable, switches to the first power conversion mode. ) To operate. If not applicable, the controller 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, as shown in FIG. 9A, an output AC power supply waveform falling to the ground voltage can be obtained. That is, the desired output AC power waveform can be obtained, and the output current quality is improved. In particular, the influence of the harmonic current component can be reduced.

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

First, FIGS. 10A to 10D are views referred to for describing operations of the switching unit 570 and the tap inductor boost converter 530.

10A and 10B illustrate a case in which the second switching device S2 of the switching unit 560 is turned on, and FIGS. 10C and 10D illustrate a second switching device S2 of the switching unit 560. Illustrates a case in which is turned off. When the second switching device S2 is turned on, the first diode D2 is turned off. When the second switching device S2 is turned off, the first diode D2 is turned on.

When the first switching device S1 in the converter 530 is turned on in the state in which the second switching device S2 of the switching unit 560 is turned on, the input as shown in FIG. 10A A closed loop is formed through the voltage Vpv, the second switching element S2, the primary side of the tap inductor T, and the first switching element S1, and the first current I1 is closed. Flow on the loop. At this time, since the secondary side of the tap inductor T has a polarity opposite to that of the primary side, the diode D1 does not conduct and is turned off. Accordingly, the energy due to the input voltage Ppv is stored on the primary side of the tap inductor T.

Next, when the first switching device S1 in the converter 530 is turned off while the second switching device S2 of the switching unit 560 is turned on, as shown in FIG. 10B. A closed loop is formed through the input voltage Vpv, the second switching element S2, the primary side, the secondary side, and the diode D1 of the tap inductor T, 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 a polarity opposite to that of the primary side, the diode D1 becomes conductive. Accordingly, the energy stored in the input voltage Ppv and the primary side and the secondary side of the tap inductor T may be stored in the capacitor C1 via the diode D1.

As described above, the converter 530 can output a high efficiency and high voltage DC power supply by using energy stored in the primary side and the secondary side of the input voltage Ppv and the tap inductor T. Accordingly, in FIGS. 10A and 10B, when the second switching device S2 of the switching unit 560 is turned on, the converter 530 may operate in a boost mode.

Next, when the first switching device S1 in the converter 530 is turned on while the second switching device S2 of the switching unit 560 is turned off, the tap inductor T Due to the energy stored on the primary side of the Ns, as shown in FIG. 10C, the second diode D2 of the switching unit 570 conducts in one direction. Accordingly, a closed loop is formed through the second diode D2, the primary side of the tap inductor T, and the first switching element S1, and the third current I3 is formed on the closed loop. Will flow. At this time, since the secondary side of the tap inductor T has a polarity opposite to that of the primary side, the diode D1 does not conduct and is turned off. As a result, the energy stored on 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 while the second switching device S2 of the switching unit 560 is turned off, as shown in FIG. 10D. The second diode D2 of the switching unit 570 conducts in one direction. Accordingly, a closed loop through the second diode D2, the second switching element S2, the primary side, the secondary side of the tab inductor T, and the diode D1, and the capacitor C1 is formed. And a second current I2 flows on the closed loop. That is, since the secondary side of the tap inductor T has a polarity opposite to that of the primary side, the diode D1 becomes conductive. Accordingly, energy stored in the primary side and the secondary side of the tap inductor T may be stored in the capacitor C1 via the diode D1.

At this time, as described in FIG. 10C, since the energy stored in the primary side of the tap inductor T is reduced, the energy stored in the secondary side is also reduced, and as a result, the voltage stored in the capacitor C1 d is lowered in voltage. Will be saved. Accordingly, in FIGS. 10C and 10D, when the second switching element 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 for the constant voltage holding period of the DC power output from the converter 530. In other sections, operate in boost mode.

FIG. 11 is a simplified circuit diagram of the power converter of FIG. 7, FIG. 12 illustrates a waveform diagram of the switching elements in the converter and the inverter, and FIG. 13 shows the final output through the first power conversion mode and the second power conversion mode. Illustrate the output AC power waveform.

The controller 550, when a constant voltage holding section corresponding to the input power Vpv among the pseudo DC powers output from the converter 530 occurs, serves as the first power conversion mode MODE 1. The second switching device S2 may be controlled to be turned off.

In addition, the controller 550 may control the first switching device S1 in the converter 530 to be switched at high speed during the first power conversion mode MODE 1, as shown in FIG. 12. For example, it can be controlled to switch at high speed at a frequency of 100 kHz.

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

On the other hand, unlike FIG. 12, the controller 550 may control the first switching device S1 in the converter 530 to perform low speed switching during the first power conversion mode MODE 1. In particular, a pulse width modulation (PWM) based switching operation may be performed to output a pseudo DC power supply.

Next, the controller 550 may control the second switching device S2 of the switching unit 560 to be turned on in the second power conversion mode MODE 2 in the period where the constant voltage maintenance section does not occur. .

In addition, the controller 550 may control the low speed switching of the first switching device S1 in the converter 530 during the second power conversion mode MODE 2. In particular, a pulse width modulation (PWM) based switching operation may be performed to output a pseudo DC power supply.

As a result, the converter 530 operates in a boost mode. As a result, as illustrated in FIG. 9A, the converter 530 outputs a voltage waveform corresponding to the pseudo DC power supply in a section excluding the constant voltage holding section.

As a result, as shown in Fig. 13, 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) are synthesized. As shown in FIG. 9A, an output voltage Vout may be output from the power converter 700.

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

On the other hand, each switching element Sa, S'a, Sb, S'b in the inverter 540 has a constant switching frequency irrespective of the first power conversion mode MODE 1 and the second power conversion mode MODE 2. According to the switching operation can be performed. For example, the switching operation may be performed at a low frequency of 100 Hz or 120 Hz.

14 is similar to FIG. 7 except that the two tap inductor boost converters 530a and 530b are used.

That is, the power converter 1400 of FIG. 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 with each other, as shown in the figure, that is, when using an interleaving method, the capacitor unit 520 and the switching unit 570 transmit the same. Since the current components are branched in parallel, the ripple of the current components output through the converters 530a and 530b is reduced. Therefore, it is possible to ensure the reliability of the capacitor provided in the capacitor unit 520.

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

That is, the power converter 1400 of FIG. 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. ) May be included.

In this case, the device characteristics of the tap inductor and the switching element in each converter 530a, 530b, and 530c may be the same.

Meanwhile, when the three tap inductor boost converters 530a and 530b are connected in parallel to each other as shown in the drawing, that is, when using the interleaving method, the capacitor unit 520 and the switching unit 570 are provided. Since the transmitted current components are branched in parallel, the ripple of the current components output through the converters 530a, 530b, and 530c is reduced. Therefore, it is possible to ensure the reliability of the capacitor provided in the capacitor unit 520.

On the other hand, the converters 530a, 530b, and 530c can operate adaptively in response to the power required values of the AC power output.

For example, if the power requirement is approximately 100W, only the first converter 530a operates, or if the power requirement is approximately 200W, only the first and second converters 530a, 530b operate, or the power requirement is approximately 300W. In this case, all of the first to third converters 530a, 530b, and 530c may operate.

Meanwhile, when at least two converters among 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.

FIG. 16 illustrates an internal circuit diagram of a junction box of the solar module of FIG. 1.

Referring to FIG. 16, the junction box 200 according to an exemplary embodiment of the present invention may include a bypass diode unit 510, a capacitor unit 520, a converter 530, a control unit 550, and a switching unit 570. It may include. That is, the inverter 540 and the filter unit 560 of the power converter 700 of FIG. 7 are not included. Not included in the junction box 200, the inverter 540 and the filter unit 540 may be provided separately.

Accordingly, the junction box 200 of FIG. 16 may 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 capacitor unit stores the DC power in the junction box, and a converter for level converting and outputting the stored DC power. Thus, DC power can be simply supplied through the junction box. In addition, the installation of the solar module is facilitated, it is advantageous for capacity expansion in the configuration of the sun and a system comprising a plurality of solar modules.

7 and 16, the junction box 200 may include only the bypass diode unit 510 and the capacitor unit 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 configuration diagram of a solar system according to an embodiment of the present invention.

Referring to the drawings, the solar system of FIG. 17 includes a plurality of solar modules 50a, 50b, ..., 50n. Each solar module 50a, 50b, ..., 50n may be provided with junction boxes 200a, 200b, ..., 200n for outputting AC power. At this time, the junction boxes 200a, 200b, ..., 200n may be referred to as junction boxes having a micro inverter, and the AC power output from each junction box 200a, 200b, ..., 200n is a system. will be supplied to the grid.

Meanwhile, according to the embodiment of the present invention, all of the power converter 700 of FIG. 7 may be mounted in the junction box 200, and the internal circuit of the junction box 200 may be applied to the micro inverter of FIG. 17. .

That is, each junction box 200a, 200b,..., 200n includes the bypass diode unit 510, the capacitor unit 520, the converter 530, and the inverter 540, as shown in FIG. 7. It may include a filter unit 560. In particular, the converter 530 may be a tap inductor boost converter 530 including a tap inductor and a switching element, as shown in FIG. 7.

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

Referring to the drawings, the photovoltaic system of FIG. 18 includes a plurality of photovoltaic modules 50a, 50b, ..., 50n. Each solar module 50a, 50b, ..., 50n may be provided with junction boxes 1200a, 1200b, ..., 1200n for outputting DC power. In addition, a separate inverter 1210 for converting the DC power output from each of the solar modules 50a, 50b, ..., 50n into AC power is further provided. At this time, the junction boxes 1200a, 1200b, ..., 1200n may be referred to as junction boxes including a power optimizer for efficiently outputting DC power.

Meanwhile, according to an embodiment of the present invention, the internal circuit of the junction box 200 of FIG. 16 may be applied to the power optimizer of FIG. 18.

That is, each junction box 200a, 200b,..., 200n may include a bypass diode unit 510, a capacitor unit 520, a converter 530, and a controller 550 as shown in FIG. 16. Can be. In particular, the converter 530 may be a tap inductor boost converter 530 including a tap inductor and a switching element, as shown in FIG. 7.

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

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

Next, a case in which power optimization is applied will be described with reference to FIG. 19B. When a hot spot occurs in some solar cell modules 1320 and some power loss occurs (for example, 70W power supply), the solar cell module 1310 may have a different current supplied from the corresponding solar cell module 1320. To lower the voltage output from the solar cell module 1320 to be equal to the current supplied from. Accordingly, some power loss occurs (for example, 70 W power supply) in the solar cell module 1320 in which the hot spot occurs, but in the normal solar cell module 1310, there is no power loss (for example, 100 W). Power supply). Thus, it is possible to supply a total of 1340W of power.

As such, according to the power optimization, the voltage supplied from the solar cell module generating the hot spot may be adjusted according to the current supplied from the other solar cell module. To this end, each solar cell module may receive a current value or a voltage value supplied from another solar cell module, and control a voltage output of the solar cell module.

Meanwhile, the junction box 200 of FIG. 16 according to an embodiment of the present invention may be applied to the power optimizer of FIG. 19B.

The power conversion device or the solar module according to the present invention is not limited to the configuration and method of the embodiments described as described above, the embodiments are all or part of each embodiment so that various modifications can be made May be optionally 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 having a switching element, the switching unit selectively outputting a DC power input;
A converter having a tap inductor and a switching element, the converter converting and outputting the level power from the switching unit; And
An inverter having a plurality of switching elements and converting the level-converted DC power into AC power;
During the turn-off period of the switching element of the switching unit, the converter operates in the first power conversion mode,
And the converter operates in a second power conversion mode during a turn-on period of the switching element of the switching unit. The method of claim 1,
The first power conversion mode is a buck (buck) mode,
And the second power conversion mode is a boost mode. The method of claim 1,
The inverter includes:
And the switching operation is performed based on a constant switching frequency during the first power conversion mode and the second power conversion mode. The method of claim 1,
The converter,
And level converting the DC power, and outputting a level converted pseudo DC power. The method according to claim 1 or 4,
And a filter unit for low-pass filtering the AC power output from the inverter. The method of claim 1,
And the first power conversion mode section corresponds to a constant voltage maintenance section of the DC power converted by the converter. The method of claim 1,
The power converter,
And a plurality of converters having a tap inductor and a switching element and connected in parallel with each other. The method of claim 7, wherein
And at least a part of the plurality of converters in response to a power required value of the output AC power. The method of claim 1,
And a control unit for controlling a switching operation of the switching element of the switching unit, the switching element of the converter, and the switching elements of the inverter. A solar cell module having a plurality of solar cells; And
And a power converter converting the DC power supplied from the solar cell module and converting the DC power into AC power.
Wherein the power conversion unit comprises:
A switching unit having a switching element, the switching unit selectively outputting a DC power input;
A converter having a tap inductor and a switching element, the converter converting and outputting the level power from the switching unit; And
An inverter having a plurality of switching elements and converting the level-converted DC power into AC power;
During the turn-off period of the switching element of the switching unit, the converter operates in the first power conversion mode,
During the turn-on period of the switching element of the switching unit, the converter is characterized in that the operation in the second power conversion mode. The method of claim 10,
The first power conversion mode is a buck (buck) mode,
The second power conversion mode is a solar module, characterized in that the boost (boost) mode. The method of claim 10,
The inverter includes:
And a switching operation based on a constant switching frequency during the first power conversion mode and the second power conversion mode. The method of claim 10,
The converter,
And level converting the DC power, and outputting a level-converted pseudo DC power. 14. The method according to claim 10 or 13,
Wherein the power conversion unit comprises:
And a filter unit for low-pass filtering the AC power output from the inverter. The method of claim 10,
The first power conversion mode section, the solar module, characterized in that corresponding to the constant voltage maintenance section of the DC power converted by the converter. The method of claim 10,
Wherein the power conversion unit comprises:
It has a tap inductor and a switching element, and has a plurality of converters connected in parallel with each other,
And at least a portion of the plurality of converters in response to power requirements of the AC power output from the power converter. The method of claim 10,
Wherein the power conversion unit comprises:
And a control unit configured to control a switching operation of the switching elements of the switching unit, the switching elements of the converter, and the switching elements of the inverter. The method of claim 10,
Wherein the power conversion unit comprises:
And a bypass diode for bypassing a solar cell in which a reverse voltage is generated among the plurality of solar cells. The method of claim 10,
The converter and inverter in the power converter are mounted in a junction box,
The junction box is attached to the solar cell module, characterized in that the solar module, characterized in that integrally configured. The method of claim 10,
The converter in the power conversion unit is mounted in the junction box,
The junction box is attached to the solar cell module, characterized in that the solar module, characterized in that integrally configured.

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