KR20210130477A - Power converting apparatus and photovoltaic module including the same - Google Patents

Abstract

The present invention relates to a power conversion device and a photovoltaic module having the same. According to an embodiment of the present invention, the power conversion device comprises: a converter for varying a level of inputted DC power; an inverter for converting DC power from the converter into AC power and outputting AC power converted to an internal power network or system; and a control unit for controlling the converter and the inverter. The control unit turns the inverter off and restarts the inverter if an output voltage is out of a first range due to an increase of the output voltage outputted from the inverter. Accordingly, the present invention can reduce an overvoltage generated according to a change of a load connected to an output terminal of the inverter.

Description

Power converting apparatus, and a solar module having the same {Power converting apparatus and photovoltaic module including the same}

The present invention relates to a power converter, and a solar module having the same, and more particularly, to a power converter capable of reducing overvoltage generated according to a change in a load connected to an output terminal of an inverter, and a power converter having the same It relates to solar modules.

The power converter is a device capable of converting the level of input power or converting input DC power into AC power.

Recently, in order to reduce energy, research on power conversion devices has been actively conducted.

Such a power converter may be used in various electric devices, and in particular, may be used in an energy supply device for supplying renewable energy.

On the other hand, the power converter converts the input power to output the converted power. When the load, which is the output terminal of the power converter, is variable, the total harmonic distortion (THD) increases according to the change of the load, There is a problem in that the quality of the output AC power is deteriorated.

In particular, when the load connected to the output terminal of the power conversion device is instantaneously changed, an overvoltage is generated according to the sudden change of the load, and consequently, the possibility of damage to the circuit elements in the power conversion device is increased.

An object of the present invention is to provide a power converter capable of reducing overvoltage generated according to a change in a load connected to an output terminal of an inverter, and a solar module having the same.

Another object of the present invention is to provide a power converter capable of protecting a circuit element when there is no filter in the output terminal of the inverter, and a solar module having the same.

A power conversion device according to an embodiment of the present invention for achieving the above object, and a photovoltaic module having the same, include a converter for varying the level of input DC power, and converting the DC power from the converter into AC power inside An inverter for outputting AC power converted to a power grid or grid, and a control unit for controlling the converter and the inverter, wherein the control unit turns off the inverter when the output voltage output from the inverter rises and out of the first range control to restart.

Meanwhile, when the inverter is restarted, the controller may control the inverter to operate based on a second gain higher than the first gain before the inverter is turned off.

Meanwhile, the controller may control the inverter to operate based on the first gain when an output voltage output from the inverter is within a first range while driving the inverter based on the second gain after restarting the inverter.

Meanwhile, the controller may control the level of the second gain to increase after the inverter is restarted as the peak of the output voltage increases while the output voltage is out of the first range.

Meanwhile, the controller may control the second gain driving period based on the second gain to increase after restarting the inverter as the peak of the output voltage increases while the output voltage is out of the first range.

Meanwhile, when the output voltage output from the inverter is within the first range after the inverter is restarted, the controller may control the inverter to operate based on the same gain as the first gain before the inverter is turned off.

Meanwhile, when the output voltage output from the inverter is within the first range after restarting the inverter, the controller may control the inverter to operate based on a gain lower than the gain after restarting the inverter.

Meanwhile, when the output voltage output from the inverter rises and is out of the first range in a state in which the system is out of power, the control unit may control the inverter to be turned off and then restarted.

Meanwhile, when the output power output from the inverter increases and is within the second range, the control unit may control the inverter to be restarted after being turned off.

The power converter according to an embodiment of the present invention, and a solar module having the same, further include an output voltage detection unit for detecting an output voltage output from the inverter, and the control unit, based on the output voltage from the output voltage detection unit , it is possible to determine whether the output voltage output from the inverter rises, out of the first range.

Meanwhile, the controller may generate a current command value for controlling the converter based on the output voltage of the inverter, and output a converter switching control signal for controlling the converter based on the current command value.

On the other hand, the control unit, based on the output voltage of the inverter and the voltage command value, a voltage controller that generates a current command value for controlling the converter, and a converter controller that generates a converter switching control signal for controlling the converter based on the current command value. may include

Meanwhile, when the inverter is restarted, the voltage controller may generate a current command value for controlling the converter based on a second gain that is higher than the first gain before the inverter is turned off.

Meanwhile, the converter includes a first leg including a first switching element and a second switching element connected in series with each other, and a second leg including a third switching element and a fourth switching element connected in series with each other, A full-bridge switching unit for converting a DC voltage to be used, a transformer having an input side connected to an output terminal of the full-bridge switching unit, and a fifth switching element and a sixth switching element electrically connected to the output side of the transformer and connected in series with each other It may include a half-bridge switching unit having a third leg.

Meanwhile, the converter may further include a resonance inductor connected between the transformer and the half-bridge switching unit.

The power converter according to an embodiment of the present invention, and a photovoltaic module having the same, are connected to a dc terminal that is an output terminal of the half-bridge switching unit, and may further include a first capacitor and a second capacitor connected in series with each other.

Meanwhile, a first node on the output side of the transformer may be connected to the resonance inductor, and a second node on the output side of the transformer may be connected to a node between the first capacitor and the second capacitor.

On the other hand, the inverter is connected to a dc terminal that is an output terminal of the half-bridge switching unit, a fourth leg including a seventh switching element and an eighth switching element connected in series with each other, and a ninth switching element and a tenth switching element connected in series with each other A fifth leg including an element may be provided, and an AC voltage may be output by converting the voltage of the dc terminal.

On the other hand, the inverter converts and outputs the positive polarity dc terminal voltage to a positive polarity voltage by turning on the seventh switching element and the tenth switching element during the first period, and during the second period, the eighth switching element and the By turning on the ninth switching element, the positive dc terminal voltage may be converted into a negative voltage and output.

A power converter according to an embodiment of the present invention, and a photovoltaic module having the same, include a converter that varies the level of input DC power, and converts DC power from the converter into AC power to be converted into an internal power grid or grid An inverter for outputting AC power, and a control unit for controlling the converter and the inverter, wherein the control unit controls to restart the inverter after turning off the inverter when the output voltage output from the inverter rises and out of a first range. Accordingly, it is possible to reduce the overvoltage generated according to a change in the load connected to the output terminal of the inverter. In addition, when there is no filter at the output terminal of the inverter, it is possible to protect the circuit element.

Meanwhile, when the inverter is restarted, the controller may control the inverter to operate based on a second gain higher than the first gain before the inverter is turned off. Accordingly, it is possible to stably operate the inverter upon restart due to a sudden load change.

Meanwhile, the controller may control the inverter to operate based on the first gain when an output voltage output from the inverter is within a first range while driving the inverter based on the second gain after restarting the inverter. Accordingly, it is possible to stably operate the inverter upon restart due to a sudden load change.

Meanwhile, the controller may control the level of the second gain to increase after the inverter is restarted as the peak of the output voltage increases while the output voltage is out of the first range. Accordingly, it is possible to quickly and stably operate the inverter upon restart due to a sudden load change.

Meanwhile, the controller may control the second gain driving period based on the second gain to increase after restarting the inverter as the peak of the output voltage increases while the output voltage is out of the first range. Accordingly, it is possible to quickly and stably operate the inverter upon restart due to a sudden load change.

Meanwhile, when the output voltage output from the inverter is within the first range after the inverter is restarted, the controller may control the inverter to operate based on the same gain as the first gain before the inverter is turned off. Accordingly, it is possible to stably operate the inverter upon restart due to a sudden load change.

Meanwhile, when the output voltage output from the inverter is within the first range after restarting the inverter, the controller may control the inverter to operate based on a gain lower than the gain after restarting the inverter. Accordingly, it is possible to stably operate the inverter upon restart due to a sudden load change.

Meanwhile, when the output voltage output from the inverter rises and is out of the first range in a state in which the system is out of power, the control unit may control the inverter to be turned off and then restarted. Accordingly, it is possible to stably operate the inverter upon restart due to a sudden load change.

Meanwhile, when the output power output from the inverter increases and is within the second range, the control unit may control the inverter to be restarted after being turned off. Accordingly, it is possible to stably operate the inverter upon restart due to a sudden load change.

The power converter according to an embodiment of the present invention, and a solar module having the same, further include an output voltage detection unit for detecting an output voltage output from the inverter, and the control unit, based on the output voltage from the output voltage detection unit , it is possible to determine whether the output voltage output from the inverter rises, out of the first range. Accordingly, it is possible to quickly grasp a sudden change in load.

Meanwhile, the controller may generate a current command value for controlling the converter based on the output voltage of the inverter, and output a converter switching control signal for controlling the converter based on the current command value. Accordingly, it is possible to stably operate the power conversion device.

On the other hand, the control unit, based on the output voltage of the inverter and the voltage command value, a voltage controller that generates a current command value for controlling the converter, and a converter controller that generates a converter switching control signal for controlling the converter based on the current command value. may include Accordingly, it is possible to stably operate the power conversion device.

Meanwhile, when the inverter is restarted, the voltage controller may generate a current command value for controlling the converter based on a second gain that is higher than the first gain before the inverter is turned off.

Meanwhile, the converter includes a first leg including a first switching element and a second switching element connected in series with each other, and a second leg including a third switching element and a fourth switching element connected in series with each other, A full-bridge switching unit for converting a DC voltage to be used, a transformer having an input side connected to an output terminal of the full-bridge switching unit, and a fifth switching element and a sixth switching element electrically connected to the output side of the transformer and connected in series with each other It may include a half-bridge switching unit having a third leg. Accordingly, it is possible to stably perform power conversion.

Meanwhile, the converter may further include a resonance inductor connected between the transformer and the half-bridge switching unit. Accordingly, the inductor current flows according to the voltage difference between the both ends of the resonant inductor, and power converted by the phase difference control between the both ends of the inductor can be controlled.

The power converter according to an embodiment of the present invention, and a photovoltaic module having the same, are connected to a dc terminal that is an output terminal of the half-bridge switching unit, and may further include a first capacitor and a second capacitor connected in series with each other. Accordingly, it is possible to output a half-wave voltage or a pulsating voltage to the dc terminal.

Meanwhile, a first node on the output side of the transformer may be connected to the resonance inductor, and a second node on the output side of the transformer may be connected to a node between the first capacitor and the second capacitor. Accordingly, it is possible to stably perform power conversion.

On the other hand, the inverter is connected to a dc terminal that is an output terminal of the half-bridge switching unit, a fourth leg including a seventh switching element and an eighth switching element connected in series with each other, and a ninth switching element and a tenth switching element connected in series with each other A fifth leg including an element may be provided, and an AC voltage may be output by converting the voltage of the dc terminal. Accordingly, it is possible to output an AC voltage having a frequency corresponding to the system voltage by the unfolding switching.

On the other hand, the inverter converts and outputs the positive polarity dc terminal voltage to a positive polarity voltage by turning on the seventh switching element and the tenth switching element during the first period, and during the second period, the eighth switching element and the By turning on the ninth switching element, the positive dc terminal voltage may be converted into a negative voltage and output. Accordingly, it is possible to output an AC voltage having a frequency corresponding to the system voltage by the unfolding switching.

1A is a diagram illustrating an example of a photovoltaic system including a photovoltaic module according to an embodiment of the present invention.
1B is a diagram illustrating another example of a photovoltaic system including a photovoltaic module according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a circuit diagram inside a junction box in the solar module of FIG. 1A or 1B .
3a to 3d are diagrams referenced in the description of the power conversion device related to the present invention.
4 is an example of a circuit diagram of a power conversion device according to an embodiment of the present invention.
5 is a diagram referenced in the description of the power conversion device of FIG.
6 is an example of an internal block diagram of the control unit of FIG. 4 .
7A to 7B are diagrams referred to in the description of FIG. 6 .
8A to 8C are diagrams referenced in the description of the operation of the power converter of FIG. 4 .
9 is a flowchart illustrating a method of operating a power conversion device according to an embodiment of the present invention.
10A to 10B are diagrams referred to in the description of FIG. 9 .
11 is a circuit diagram of a power conversion device according to an embodiment of the present invention.
12A to 14C are diagrams referenced in the description of the power converter of FIG. 11 .
15 is a diagram referenced to describe a buck mode operation.
16 is a diagram referenced to describe a boost mode operation.
17 is an exploded perspective view of the solar cell module of FIG. 1A or 1B.

In the present specification, a method for reducing the ripple of the input current input to the converter in the solar module is proposed.

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

The suffixes "module" and "part" for the components used in the following description are given simply in consideration of the ease of writing the present specification, and do not give a particularly important meaning or role by themselves. Accordingly, the terms “module” and “unit” may be used interchangeably.

1A is a diagram illustrating an example of a photovoltaic system including a photovoltaic module according to an embodiment of the present invention.

Referring to the drawings, a photovoltaic system 10a according to an embodiment of the present invention may include a photovoltaic module 50 and a gateway 80 .

The solar module 50 is integrally provided with a junction box 200 including a solar cell module 100 and a power converter (500 in FIG. 2 ) that converts and outputs DC power from the solar cell module. can do.

In the drawings, the junction box 200 is attached to the rear surface of the solar cell module 100 , but is not limited thereto. The junction box 200 may be provided separately from the solar cell module 100 .

Meanwhile, a cable oln for supplying AC power output from the junction box 200 to the grid may be electrically connected to an output terminal of the junction box 200 .

Meanwhile, the gateway 80 may be located between the junction box 200 and the grid 90 .

Meanwhile, the gateway 80 may detect an AC current io and an AC voltage vo output from the solar module 50 flowing through the cable oln.

Meanwhile, the gateway 80 may output a power factor adjustment signal for power factor adjustment based on a phase difference between the AC current io and the AC voltage vo output from the solar module 50 .

To this end, the gateway 80 and the solar module 50 may perform power line communication (PLC communication), etc. using the cable 323 .

On the other hand, the power conversion device (500 in FIG. 2) in the solar module 50 may convert the DC power output from the solar cell module 100 into AC power and output it.

To this end, a converter (530 in FIG. 2 ) and an inverter (540 in FIG. 2 ) may be provided in the power conversion device ( 500 in FIG. 2 ) in the solar module 50 .

On the other hand, the power conversion device (500 in FIG. 2) may be called a micro-inverter. Accordingly, the micro-inverter may include a converter ( 530 in FIG. 2 ) and an inverter ( 540 in FIG. 2 ).

On the other hand, in the present invention, in the output terminal of the power conversion device 500, in a state in which a filter including an inductor and a capacitor is not disposed, when a load change rapidly changes, a method of preventing the output voltage from rising rapidly is proposed. do.

To this end, the power conversion device 500 according to an embodiment of the present invention includes a converter 530 for varying the level of an input DC power, and converts the DC power from the converter 530 into AC power to generate an internal power grid or It includes an inverter 540 that outputs AC power converted into a grid, and a controller 550 that controls the converter 530 and the inverter 540 , and the controller 550 includes an output voltage output from the inverter 540 . When this rises and is out of the first range Vrar, the inverter 540 is turned off and then restarted. Accordingly, it is possible to reduce the overvoltage generated according to a change in the load connected to the output terminal of the inverter 540 . In addition, when there is no filter at the output terminal of the inverter 540, it is possible to protect the circuit element.

Next, FIG. 1B is a view showing another example of a solar system including a solar module according to an embodiment of the present invention.

Referring to the drawings, a photovoltaic system 10b according to an embodiment of the present invention may include a plurality of photovoltaic modules 50a, 50b, ..., 50n, and a gateway 80 .

The photovoltaic system 10b of FIG. 1b is different from the photovoltaic system 10a of FIG. 1a in that a plurality of photovoltaic modules 50a, 50b, ..., 50n are serially connected to each other.

A plurality of photovoltaic modules (50a, 50b, ..., 50n) each, each solar cell module (100a, 100b, ..., 100n), and a circuit for converting the DC power from the solar cell module to power conversion Junction boxes 200a, 200b, ..., 200n including devices may be provided.

In the drawings, each junction box (200a, 200b, ..., 200n) is shown attached to the rear surface of each solar cell module (100a, 100b, ..., 100n), but is not limited thereto. Each of the junction boxes 200a, 200b, ..., 200n may be provided separately from each of the solar cell modules 100a, 100b, ..., 100n.

On the other hand, the cables 31a, 31b, ..., oln for supplying AC power output from each of the junction boxes 200a, 200b, ..., 200n to the grid, each of the junction boxes 200a, 200b, . .., 200n) can be electrically connected to the output terminal.

On the other hand, each power conversion device 500 in the plurality of photovoltaic modules 50a, 50b, ..., 50n of FIG. 1b, reduces the overvoltage generated according to a change in the load connected to the output terminal of the inverter 540 In order to do this, the converter 530 for varying the level of the input DC power, and the inverter 540 for converting the DC power from the converter 530 to AC power and outputting the AC power converted to the internal power grid or grid; A converter 530 and a control unit 550 for controlling the inverter 540 is provided, and the control unit 550 increases the output voltage output from the inverter 540 and, when out of the first range Vrar, the inverter After the 540 is turned off, it is controlled to be restarted. Accordingly, it is possible to reduce the overvoltage generated according to a change in the load connected to the output terminal of the inverter 540 . In addition, when there is no filter at the output terminal of the inverter 540, it is possible to protect the circuit element.

FIG. 2 is a diagram illustrating a circuit diagram inside a junction box in the solar module of FIG. 1A or 1B .

Referring to the drawings, the junction box 200 may convert DC power from the solar cell module 100 to output the converted power.

In particular, in relation to the present invention, the junction box 200 may include a power conversion device 500 for outputting AC power.

To this end, the power conversion device 500 may include a converter 530 , an inverter 540 , and a controller 550 for controlling the same.

In addition, the power converter 500 may further include a bypass diode unit 510 for bypassing and a capacitor unit 520 for storing DC power.

Meanwhile, the power conversion device 500 may further include a communication unit 580 for communication with the external gateway 80 .

On the other hand, the power converter 500, the input current detection unit (A), the input voltage detection unit (B), the converter output current detection unit (C), the converter output voltage detection unit (D), the inverter output current detection unit (E), the inverter output It may further include a voltage detection unit (F).

Meanwhile, the controller 550 may control the converter 530 , the inverter 540 , and the communication unit 580 .

The bypass diode unit 510 may include bypass diodes Dc, Db, and Da respectively disposed between the first to fourth conductive lines (not shown) of the solar cell module 100 . . At this time, the number of bypass diodes is one or more, and it is preferable that one is smaller than the number of conductive lines.

The bypass diodes Dc, Db, and Da receive solar DC power from the solar cell module 100 , in particular, from the first to fourth conductive lines (not shown) in the solar cell module 100 . In addition, the bypass diodes Dc, Db, and Da may be bypassed when a reverse voltage is generated from the DC power source from at least one of the first to fourth conductive lines (not shown).

Meanwhile, the DC power passing through the bypass diode unit 510 may be input to the capacitor unit 520 .

The capacitor unit 520 may store input DC power input through the solar cell module 100 and the bypass diode unit 510 .

Meanwhile, in the drawings, the capacitor unit 520 is exemplified as having a plurality of capacitors Ca, Cb, and Cc connected in parallel to each other. It is also possible to connect to the stage. Alternatively, the capacitor unit 520 may include only one capacitor.

The converter 530 may convert the level of the input voltage from the solar cell module 100 through the bypass diode unit 510 and the capacitor unit 520 .

In particular, the converter 530 may perform power conversion by using the DC power stored in the capacitor unit 520 .

Meanwhile, the switching elements in the converter 530 may be turned on/off based on a converter switching control signal from the controller 550 . Accordingly, the level-converted DC power may be output.

The inverter 540 may convert the DC power converted by the converter 530 into AC power and output the AC power converted to the internal power grid or grid. In this case, a filter including an inductor, a capacitor, etc. may not be disposed at the output terminal of the inverter 540 .

For example, the inverter 540 may be a full-bridge inverter.

That is, the upper-arm switching elements SW1 and SW3 and the lower-arm switching elements SW2 and SW4 respectively connected in series in the inverter 540 become a pair, and a total of two pairs of the upper and lower arm switching elements are parallel to each other (SW1, SW2). , SW3, SW4). Diodes D1 to D4 may be connected in anti-parallel to each of the switching elements SW1 to SW4.

The switching elements SW1 to SW4 in the inverter 540 may turn on/off based on an inverter switching control signal from the controller 550 . Thereby, AC power having a predetermined frequency can be output. Preferably, it has a frequency equal to the alternating frequency of the grid voltage (approximately 60 Hz or 50 Hz).

Meanwhile, the capacitor C may be disposed between the converter 530 and the inverter 540 .

The capacitor C may store the level-converted DC power of the converter 530 . Meanwhile, both ends of the capacitor C may be referred to as a dc terminal, and accordingly, the capacitor C may be referred to as a dc terminal capacitor.

In the drawings, one capacitor is exemplified, but it is possible that a plurality of capacitors are disposed in the dc terminal.

Meanwhile, the input current detection unit A may detect the input current ic1 supplied from the solar cell module 100 to the capacitor unit 520 .

Meanwhile, the input voltage detection unit B may detect the input voltage Vc1 supplied from the solar cell module 100 to the capacitor unit 520 . Here, the input voltage Vc1 may be the same as the voltage stored across the capacitor unit 520 .

The detected input current ic1 and input voltage vc1 may be input to the controller 550 .

Meanwhile, the converter output current detection unit C detects the output current ic2 output from the converter 530 , that is, a dc terminal current, and the converter output voltage detection unit D includes an output voltage output from the converter 530 . (vc2), that is, the dc terminal voltage is detected. The detected output current ic2 and output voltage vc2 may be input to the controller 550 .

Meanwhile, the inverter output current detection unit E detects a current ic3 output from the inverter 540 , and the inverter output voltage detection unit F detects a voltage vc3 output from the inverter 540 . The detected current ic3 and voltage vc3 are input to the control unit 550 .

Meanwhile, the controller 550 may output a control signal for controlling the switching elements of the converter 530 . In particular, the control unit 550, the detected input current (ic1), the input voltage (vc1), the output current (ic2), the output voltage (vc2), the output current (ic3), or at least one of the output voltage (vc3) Based on this, turn-on timing signals of the switching elements in the converter 530 may be output.

Meanwhile, the controller 550 may output an inverter control signal or an inverter switching control signal Sic for controlling each of the switching elements SW1 to SW4 of the inverter 540 . In particular, the control unit 550, the detected input current (ic1), the input voltage (vc1), the output current (ic2), the output voltage (vc2), the output current (ic3), or at least one of the output voltage (vc3) Based on the turn-on timing signal of each of the switching elements SW1 to SW4 of the inverter 540 may be output.

Meanwhile, the control unit 550 may control the converter 530 to calculate a maximum power point for the solar cell module 100 and, accordingly, output a DC power corresponding to the maximum power. This control may be called MPPT control.

Meanwhile, the communication unit 580 may communicate with the gateway 80 .

For example, the communication unit 580 may exchange data with the gateway 80 through power line communication.

Meanwhile, the communication unit 580 may transmit current information, voltage information, power information, and the like of the solar module 50 to the gateway 80 .

3a to 3d are diagrams referenced in the description of the power conversion device related to the present invention.

First, Figure 3a illustrates a circuit diagram of the power conversion device (500x) related to the present invention.

Referring to the drawings, the power conversion device 500x of FIG. 3A includes an inverter 540 , a controller 550 for controlling the inverter 540 , and an inverter 540 are disposed at an output terminal and output from the inverter 540 . It may be provided with a filter unit 570 for filtering the AC power.

The inverter 540 includes a fourth leg including a seventh switching element SW1 and an eighth switching element SW2 that are serially connected to each other, and a ninth and tenth switching element SW9 and a tenth that are connected in series with each other. A fifth leg including the switching element SW4 may be provided. At this time, the fourth leg and the fifth leg are connected in parallel to each other.

On the other hand, when the filter unit 570 is disposed, the AC power output from the inverter 540 is filtered, but due to the circuit elements in the filter unit 570, the size of the power conversion device 500x increases. Also, due to the filter unit 570, output power may be consumed.

3B is a diagram referenced to explain asynchronous pulse width variable control.

Referring to the drawing, during the Pd4 period before the Tzcx time point corresponding to the zero crossing point Zcx in which the output voltage waveform Vgx output from the inverter 540 changes from the positive polarity to the negative polarity, the The seventh switching element SW1 and the eighth switching element SW2 perform high-speed switching, and the ninth switching element SW3 and the tenth switching element SW4 of the fifth leg perform low-speed switching. can do.

Similarly, during the Pd3 period after the Tzcx time point corresponding to the zero crossing point Zcx, the seventh switching element SW1 and the eighth switching element SW2 of the fourth leg perform high-speed switching, , the ninth switching element SW3 and the tenth switching element SW4 of the fifth leg may perform low-speed switching.

According to FIG. 3B , during the Pdx period including the zero crossing point Zcx, all of the seventh to tenth switching elements SW1 to SW4 in the inverter 540 are not switched and are turned off. This Pdx period may be referred to as a dead time period.

Such a Pdx period may exist in order to reduce switching losses of the seventh to tenth switching elements SW1 to SW4.

On the other hand, as shown in FIG. 3c , when the current Igxa output from the inverter 540 lags behind the output voltage Vgxa and is on the ground, due to the dead time section of the Pdx section of FIG. 3b , the inverter 540 In the vicinity of the zero crossing point of the voltage Vgxa output from , a current peak Pka may occur due to current discontinuity or the like.

On the other hand, as shown in FIG. 3D , when the current Igxb output from the inverter 540 is ahead of the output voltage Vgxb, due to the dead time section of the Pdx section of FIG. 3B , the inverter 540 In the vicinity of the zero crossing point of the output voltage Vgxb, a current peak Pkb due to current discontinuity or the like may occur.

In the present invention, a method for improving current quality by reducing current peaks that may occur during asynchronous pulse width variable control of the inverter 540 is proposed. This will be described with reference to FIG. 4 and below.

4 is a circuit diagram of a power conversion device in a solar module according to an embodiment of the present invention, and FIG. 5 is a diagram referenced in the description of the power conversion device of FIG.

Referring to the drawings, the power conversion device 500 according to an embodiment of the present invention may include a converter 530 , an inverter 540 , and a controller 550 .

On the other hand, the control unit 550 according to the embodiment of the present invention, the control unit 550, when the output voltage output from the inverter 540 rises, out of the first range (Vrar), the inverter 540 is turned off After that, control to restart. Accordingly, it is possible to reduce the overvoltage generated according to a change in the load connected to the output terminal of the inverter 540 . In addition, when there is no filter at the output terminal of the inverter 540, it is possible to protect the circuit element.

Meanwhile, when the inverter 540 is restarted, the controller 550 may control the inverter 540 to operate based on a second gain higher than the first gain before the inverter 540 is turned off. Accordingly, it is possible to stably operate the inverter 540 when restarting according to a sudden load change.

On the other hand, the controller 550 drives the inverter 540 based on the second gain after the inverter 540 is restarted, and when the output voltage output from the inverter 540 is within the first range Vrar, Based on the first gain, the inverter 540 may be controlled to operate. Accordingly, it is possible to stably operate the inverter 540 when restarting according to a sudden load change.

The power conversion device 500 according to an embodiment of the present invention may further include an output voltage detection unit F for detecting the output voltage Vac output from the inverter 540 .

Meanwhile, the controller 550 may determine whether the output voltage output from the inverter 540 rises and is out of the first range Vrar, based on the output voltage from the output voltage detector. Accordingly, it is possible to quickly grasp a sudden change in load.

Meanwhile, the control unit 550 may calculate the load power of the output terminal of the inverter 540 based on the output voltage Vac of the output voltage detection unit F.

Power conversion device 500 according to an embodiment of the present invention, the output voltage detection unit (F) for detecting the output voltage (Vac) output from the inverter (540), and detecting the voltage (Vpv) of the DC power input An input voltage detection unit A1 may be further provided.

Meanwhile, the control unit 550 controls the converter 530 based on the output voltage Vac detected by the output voltage detection unit F and the input voltage Vpv detected by the input voltage detection unit A1 . signal can be output.

Power conversion device 500 according to an embodiment of the present invention, the output voltage detector (F) for detecting the output voltage (Vac) output from the inverter 540, and detecting the current (Ipv) of the DC power input An input current detection unit A2 may be further provided.

Meanwhile, the controller 550 is a converter for controlling the converter 530 based on the output voltage Vac detected by the output voltage detection unit F and the input current Ipv detected by the input current detection unit A2 . A switching control signal Scc may be output. Accordingly, it is possible to stably operate the power converter 500 .

Meanwhile, the control unit 550 generates a current command value for controlling the converter 530 based on the output voltage of the inverter 540 and the voltage command value, and based on the current command value, the converter for controlling the converter 530 . A switching control signal Scc may be output. Accordingly, it is possible to stably operate the power converter 500 .

On the other hand, the converter 530 according to an embodiment of the present invention, the full bridge switching unit 532 for converting the input DC voltage (Vpv), and the input side is connected to the output terminal of the full bridge switching unit 532, It includes a transformer 536 for outputting the converted voltage, and a half-bridge switching unit 538 electrically connected to an output side of the transformer 536 .

Accordingly, it is possible to improve the quality of the output AC power. In particular, it is possible to perform wide voltage gain output and zero voltage switching. In addition, high efficiency driving is possible even in a wide voltage range with low effective value (RMS) current and peak current. In addition, one-stage power conversion through half-wave rectification control becomes possible.

On the other hand, the converter 530 according to an embodiment of the present invention is connected between the half-bridge switching unit 538 connected to the output side of the transformer 536, and the transformer 536 and the half-bridge switching unit 538. , may further include a resonance inductor (Lk). Accordingly, an inductor current flows according to a voltage difference between both ends of the resonant inductor Lk, and power converted by the phase difference control between both ends of the inductor can be controlled.

On the other hand, due to resonance by the resonance inductor Lk and the transformer 536, the ripple of the input current can be reduced.

Meanwhile, each of the switching elements Q1 to Q4 in the full-bridge switching unit 532 may perform zero voltage switching (ZVS) and zero current switching (ZCS) by the resonance inductor Lk or the like.

On the other hand, the power conversion device 500 according to an embodiment of the present invention is connected to the dc terminal that is the output terminal of the half-bridge switching unit 538, the first capacitor C1 and the second capacitor C2 connected in series with each other. ) may be further included. Accordingly, it is possible to output a half-wave voltage or a pulsating voltage to the dc terminal.

On the other hand, the first node nb1 on the output side of the transformer 536 is connected to the resonance inductor Lk, and the second node nb2 on the output side of the transformer 536 is the first capacitor C1 and the second It is connected to the node n4 between the capacitors C2. Accordingly, it is possible to output a half-wave voltage or a pulsating voltage to the dc terminal.

Meanwhile, the converter 530 according to an embodiment of the present invention may further include a third capacitor Cm connected to both ends of the input terminal of the full-bridge switching unit 532 .

On the other hand, the first node na1 on the input side is connected to the node n1 between the first switching element Q1 and the second switching element Q2, and the second node na2 on the input side is the third It is connected to the node n2 between the switching element Q3 and the fourth switching element Q4.

As shown in the figure, the full-bridge switching unit 532 is a first leg having first to second switching elements Q1 and Q2 connected in series with each other, and third to fourth connected in series with each other. A second leg including switching elements Q3 and Q4 may be provided.

A first leg and a second leg may be connected in parallel to each other.

And, the first node n1 between the first switching element Q1 and the second switching element Q2, and the second node between the third switching element Q3 and the fourth switching element Q4) Between (n2), the input sides (na1, na2) of the transformer 536 may be connected.

Meanwhile, the inverter 540 includes a fourth leg having seventh and eighth switching elements SW1 and SW2 connected in series with each other, and ninth and tenth switching elements SW3 and SW4 connected in series with each other. ) may include a fifth leg (leg) having.

Through the fifth node n5 between the seventh switching element SW1 and the eighth switching element SW2 and the sixth node n6 between the ninth switching element SW9 and the tenth switching element SW4 , AC power may be output.

Meanwhile, as shown in the drawing, the half-bridge switching unit 538 may include a third leg including a fifth switching element S1 and a sixth switching element S2 connected in series to each other. .

Meanwhile, a first capacitor C1 and a second capacitor C2 connected in series to each other may be disposed at a dc terminal that is an output terminal of the half-bridge switching unit 538 .

In this case, the fifth switching element S1 , the sixth switching element S2 , the first capacitor C1 , and the second capacitor C2 may be connected in parallel to each other.

Between the third node n3 between the fifth switching element S1 and the sixth switching element S2 and the fourth node n4 between the first capacitor C1 and the second capacitor C2, Output sides nb1 and nb2 of the transformer 536 may be connected.

Meanwhile, since the half-bridge switching unit 538 amplifies and outputs the input voltage twice, it may be referred to as a voltage doubler.

Meanwhile, the controller 550 may control the converter 530 and the inverter 540 together.

In particular, the controller 550 may output the control signal Sfb to the full-bridge switching unit 532 in the converter 530 for maximum power point tracking control.

Meanwhile, the controller 550 may output a control signal Shb to the half-bridge switching unit 538 to control the half-bridge switching unit 538 .

Meanwhile, the controller 550 may output a control signal Sic to the inverter 540 for controlling the inverter 540 .

5 is a diagram referenced to explain the operation of the inverter.

Referring to the drawing, during the first period, by turning on the seventh switching element SW1 and the tenth switching element SW10 in the inverter 540, a positive dc terminal voltage Vdc is converted into a positive voltage. and output, and during the second period, by turning on the eighth switching element SW2 and the ninth switching element SW3 in the inverter 540, the positive dc terminal voltage Vdc is converted into a negative voltage. can be printed out.

By such unfolding switching, it is possible to convert the half-wave voltage or pulsating voltage Vdcm at both ends of the dc terminal into an AC voltage Vacm having a frequency corresponding to the grid voltage Vac and output it.

6 is an example of an internal block diagram of the control unit of FIG. 4 .

Referring to the drawing, the control unit 550 includes a voltage controller 920 that generates a current command value for controlling the converter 530 based on the output voltage of the inverter 540 and the voltage command value, and the current command value based on the current command value. , a converter controller 940 that generates a converter switching control signal Scc for controlling the converter 530 . Accordingly, it is possible to stably operate the power conversion device. In addition, by the operation of the converter 530, it is possible to perform a load operation corresponding to the load.

Meanwhile, when the inverter 540 is restarted, the voltage controller 920 may generate a current command value for controlling the converter 530 based on a second gain higher than the first gain before the inverter 540 is turned off. . Accordingly, it is possible to reduce the overvoltage generated according to a change in the load connected to the output terminal of the inverter 540 . In addition, when there is no filter at the output terminal of the inverter 540, it is possible to protect the circuit element.

Meanwhile, the controller 550 may further include a phase detector 905 that detects the phase θg based on the output voltage Vac from the output voltage detector F. FIG.

The phase θg detected by the phase detector 905 is input to the voltage controller 920 .

Meanwhile, the control unit 550 calculates the maximum power point for the solar cell module 100, and accordingly, the MPPT controller 910 that generates a voltage command value Vref for outputting a DC power corresponding to the maximum power. ) may be further provided.

The MPPT controller 910 calculates a maximum power point based on the input voltage Vpv or the input current Ipv from the input voltage detection unit A1 or the input current detection unit A2, and, accordingly, to the maximum power A voltage reference value Vref for outputting a corresponding DC power may be generated.

Meanwhile, the MPPT controller 910 may output a load voltage Vload.

At this time, the load voltage Vload may be generated based on the output voltage Vac detected by the output voltage detector F.

On the other hand, the converter controller 920 compares the load voltage (Vload) and the voltage command value (Vref), and based on the difference, the d-axis current command value (Ide,ref) and the q-axis current command value (Iqe,ref) You can create and print it.

In addition, the converter controller 940 may generate the converter switching control signal Scc based on the input current command values Ide, ref, Iqe, ref.

At this time, the converter switching control signal (Scc) is a full-bridge switching control signal (Sfb) for the full-bridge switching unit 532 of FIG. 4 and a half-bridge switching control signal (Shb) for the half-bridge switching unit 538 of FIG. may include

Meanwhile, the control unit 550 may further include a variable frequency controller 930 for varying the switching frequency of the full-bridge switching unit 532 .

For example, the variable frequency controller 930, when the voltage across the dc terminal is equal to or greater than the target voltage, the full-bridge switching unit 532 operates in the buck mode, and the full-bridge switching unit 532 operates in the first switching frequency. Control to operate, and when the voltage across the dc terminal is less than the target voltage, the half-bridge switching unit 538, which is the half-bridge switching unit, operates in the boost mode, and the full-bridge switching unit 532 and the half-bridge switching unit 538 may be controlled to operate at a second switching frequency lower than the first switching frequency.

Meanwhile, the controller 550 may further include an unfolding controller 950 for controlling the unfolding switching of the inverter 540 .

As shown in FIG. 5 , the unfolding controller 950 converts the positive dc terminal voltage Vdc to the positive polarity by turning on the seventh switching element SW1 and the tenth switching element SW10 during the first period. It is converted into a voltage and output, and during the second period, by turning on the eighth switching element SW2 and the ninth switching element SW3, the positive dc terminal voltage Vdc is converted to a negative voltage and output can be controlled to do so.

By such unfolding switching, it is possible to convert the half-wave voltage or pulsating voltage Vdcm at both ends of the dc terminal into an AC voltage Vacm having a frequency corresponding to the grid voltage Vac and output it.

7A is a diagram illustrating a load voltage Vacm, a load current Iacm, and a dc terminal voltage Vdcm when the load of the output terminal of the inverter 540 is the first power.

Referring to the drawings, when the first power is approximately 300W, the load voltage Vacm and the load current Iacm each correspond to an AC waveform, and the dc terminal voltage Vdcm may correspond to a pulsating waveform in the form of a half wave. .

7B is a diagram illustrating a load voltage Vacm2 and a load current Iacm2 when the load of the output terminal of the inverter 540 is no load.

Referring to the drawing, when the grid 90, which is the output terminal of the inverter 540, is out of power and there is no load, there is no load to consume the current flowing through the output terminal of the inverter 540, so the load current corresponding to the zero level DC current (Iacm2) is preferably output.

In this case, it is preferable that the load voltage Vacm2 is an AC voltage waveform, but the load current Iacm2 corresponds to a DC current of approximately zero level.

To this end, as described above, the controller 5500 controls the converter 530 through the converter controller 920 to perform a load corresponding operation. In addition, the quality of the output AC power can be improved according to the load response operation.

On the other hand, even when the system 90, which is an output terminal of the inverter 540, is out of power, it is possible to reduce unnecessary power consumption even when there is no load.

On the other hand, the control unit 550 of FIG. 4 may vary the switching frequency of the full-bridge switching unit 532 based on the input voltage of the converter 530 or the voltage across the dc terminal.

Specifically, the control unit 550 may control the full-bridge switching unit 532 to operate in a buck mode or a boost mode according to the voltage level of both ends of the dc terminal.

On the other hand, the control unit 550, when the voltage across the dc terminal is equal to or greater than the target voltage, the full bridge switching unit 532 controls to operate in the buck mode, and when the voltage across the dc terminal is less than the target voltage, half-bridge switching The negative half-bridge switching unit 538 may be controlled to operate in the boost mode.

On the other hand, the control unit 550, when the voltage across the dc terminal is equal to or greater than the target voltage, the full-bridge switching unit 532 operates in the buck mode, and controls the full-bridge switching unit 532 to operate at the first switching frequency, , when the voltage across the dc terminal is less than the target voltage, the half-bridge switching unit 538 that is the half-bridge switching unit operates in the boost mode, and the full-bridge switching unit 532 and the half-bridge switching unit 538 perform the first switching It can be controlled to operate at a second switching frequency lower than the frequency.

On the other hand, it is preferable that the switching frequency of the full bridge switching part 532 is larger than a system frequency.

For example, the first switching frequency may be 135 kHz, but the second switching frequency may be 90 Khz. Accordingly, since high-speed switching is performed, the circuit element in the converter 530 can be miniaturized. In particular, the transformer 536 can be downsized.

On the other hand, the control unit 550, through the buck mode or the boost mode, as a result, may control so that the ripple of the voltage across the dc terminal is reduced.

Meanwhile, the controller 550 performs switching among the plurality of switching elements SW1 to SW4 in the inverter 540 according to the third switching frequency, and the other part performs switching at a fourth switching frequency higher than the third switching frequency. It can be controlled to perform switching according to

That is, the controller 550 may perform asynchronous pulse width variable control for the inverter 540 .

At this time, since the third switching frequency corresponds to the grid frequency, and the fourth switching frequency is higher than the grid frequency, the inverter 540 can perform high-speed switching, thus reducing the size of the circuit element in the power conversion device becomes possible Accordingly, the power conversion device can be miniaturized.

Meanwhile, the control unit 550 controls the seventh and eighth switching elements SW1 and SW2 to operate at the fourth switching frequency, and the ninth and tenth switching elements SW3 and SW4 for the third It can be controlled to operate at a switching frequency.

Meanwhile, the control unit 550 controls the seventh switching element SW1 and the eighth switching element SW2 to perform switching by the pulse width variable control while the ninth switching element SW3 is turned on, 10 While the switching element SW4 is turned on, the eighth switching element SW2 and the seventh switching element SW1 may be controlled to perform switching according to the pulse width variable control.

On the other hand, some of the plurality of switching elements SW1 to SW4 in the inverter 540 (SW3, SW4) and the other part (SW1, SW2) of the plurality of switching elements (SW1 to SW4) are different types of switching elements can be

On the other hand, the other part (SW1, SW2) of the plurality of switching elements (SW1 ~ SW4) in the inverter 540, for example, as a switching element for performing high-speed switching, gallium nitride (GaN) transistor or silicon carbide A (SiC) transistor may be included, and thus, it is possible to reduce the reverse recovery loss during high-speed switching.

On the other hand, some of the plurality of switching elements SW1 to SW4 in the inverter 540 (SW3, SW4), for example, the switching element performing low-speed switching, a metal oxide semiconductor field effect transistor (MOSFET) can

8A to 8C are diagrams referenced in the description of the operation of the power converter of FIG. 4 .

8A is an example of an internal circuit diagram of a power conversion device according to an embodiment of the present invention.

Referring to the drawings, the power conversion device 500 according to an embodiment of the present invention includes a converter 530 for varying the level of input DC power, and converts DC power from the converter 530 into AC power inside It may include an inverter 540 that outputs AC power converted to a power grid or grid, and a controller 550 that controls the converter 530 and the inverter 540 .

In this case, a filter including an inductor or a capacitor is not provided at the output terminal of the inverter 540 . Accordingly, the size of the power conversion device 500 is reduced, it is possible to reduce unnecessary consumption of output power.

The converter 530, the full-bridge switching unit 532 for converting the input DC voltage (Vpv), the input side is connected to the output terminal of the full-bridge switching unit 532, a transformer 536 for outputting the converted voltage and a half-bridge switching unit 538 electrically connected to the output side of the transformer 536 .

Full-bridge switching unit 532, a first leg having a first to second switching elements (Q1, Q2) connected in series with each other, and third to fourth switching elements (Q3) connected in series with each other, Q4) with a second leg.

The half-bridge switching unit 538 may include a third leg including a fifth switching element S1 and a sixth switching element S2 connected in series to each other.

On the other hand, the converter 530, a half-bridge switching unit 538 connected to the output side of the transformer 536, and a resonant inductor (Lk) connected between the transformer 536 and the half-bridge switching unit 538 are further added can be provided

Accordingly, the converter 530 may convert the level of the input DC voltage Vpv to output a half-wave voltage or a pulsating voltage to the dc terminal.

The inverter 540 includes a fourth leg having seventh and eighth switching elements SW1 and SW2 connected in series with each other, and ninth and tenth switching elements SW3 and SW4 connected in series with each other. It may include a fifth leg (leg) provided with.

On the other hand, the inverter 540 converts the half-wave voltage or pulsating voltage (Vdcm) of both ends of the dc terminal into an alternating voltage (Vacm) of a frequency corresponding to the grid voltage (Vac) by unfolding switching and can be output. there will be

The output terminal of the inverter 540 is electrically connected to the internal power grid or system 90 , and the output voltage output from the inverter 540 may be supplied to the load 900 in the internal power grid or the system 90 . .

8B illustrates the waveform Vacm of the output voltage of the inverter 540 .

Referring to the drawings, it is exemplified that the output voltage of the inverter 540 is maintained within a first range Vrar between LVP and -LVP during the Pax period.

For example, when the level of the load 900 in the internal power grid of FIG. 8A is the first level, the output voltage of the inverter 540 may be maintained within the first range Vrar as shown in FIG. 8B .

On the other hand, at the time Tm1a, when the level of the load 900 in the internal power grid is lowered to the second level, which is much smaller than the first level, since the filter is not disposed at the output terminal of the inverter 540, the output voltage of the inverter 540 will rise sharply.

In the drawing, it is exemplified that the level of the output voltage of the inverter 540 at the time Tm1a is out of the first range Vrar and is Lv2. In particular, in the Ar region, it is exemplified that the level of the output voltage of the inverter 540 is Lv2 outside the first range Vrar.

In addition, during the Pbx period, the level of the output voltage of the inverter 540 may be out of the first range Vrar.

After the Pbx period, during the Pcx period, the level of the output voltage of the inverter 540 may be maintained within the first range Vrar again.

On the other hand, as the Pbx period becomes longer, that is, as the level of the output voltage of the inverter 540, the period out of the first range (Vrar) becomes longer, each circuit in the power conversion device 500 including the inverter 540 The possibility of damage to the element or the like increases.

Accordingly, in the present invention, when the level of the output voltage of the inverter 540 sharply rises according to a sudden load drop in a state in which the filter is not disposed at the output terminal of the inverter 540 , each circuit element in the power conversion device 500 . Suggests a method to reduce the possibility of burnout. This will be described with reference to FIG. 9 and below.

8C illustrates the waveform Pm of the output power of the inverter 540 .

Referring to the drawing, it is exemplified that the output power of the inverter 540 is out of the second range Prar between LP and -LP before the time Tm2. Accordingly, the output power is stably output.

On the other hand, when the level of the load 900 in the internal power grid is lowered to the second level, which is much smaller than the first level, at the time Tm2 , the filter is not disposed at the output terminal of the inverter 540 , so the output power of the inverter 540 . falls rapidly.

In the figure, it is exemplified that the level of the output power of the inverter 540 at the time Tm2 is maintained within the second range Prar. In particular, it is exemplified that the peak level of the output power of the inverter 540 after the time Tm2 is Lp2.

On the other hand, at the time Tm2, when the level of the output power of the inverter 540 is abruptly lowered, the possibility of damage to each circuit element in the power conversion device 500 including the inverter 540 increases.

Accordingly, in the present invention, when the level of the output power of the inverter 540 is abruptly lowered in a state where the filter is not disposed at the output terminal of the inverter 540, each circuit element in the power conversion device 500, etc. Suggest ways to reduce the possibility of burnout. This will be described with reference to FIG. 9 and below.

9 is a flowchart illustrating a method of operating a power conversion device according to an embodiment of the present invention.

Referring to the drawings, the control unit 550 in the power conversion device 500 according to an embodiment of the present invention determines whether the grid is off (S905).

For example, the control unit 550 in the power conversion device 500 may receive grid-off information or blackout information from a communication unit (not shown), and based on this, determine whether the grid 90 is off can judge

As another example, the control unit 550 in the power conversion device 500, while the operation of the inverter 540 is stopped, based on the level of the output voltage detected by the output voltage detection unit (A), whether the grid 90 is off can determine whether

Specifically, when the level of the output voltage detected by the output voltage detection unit A is less than or equal to the reference level while the inverter 540 is stopped, it may be determined that the grid 90 is in an off or blackout state.

On the other hand, in a grid-off or blackout state, and in a state in which the inverter 540 operates, the control unit 550 in the power conversion device 500 determines whether the output voltage rises (S910), and if applicable, It may be determined whether the output voltage is within a predetermined range, for example, out of the first range or within the first range ( S915 ).

For example, in a grid-off or power outage state, in a state in which the inverter 540 operates, when the level of the load 900 of FIG. 8A sharply decreases from the first level to the second level, the power conversion device 500 The controller 550 may determine whether the load level is rapidly reduced using the output voltage.

On the other hand, the control unit 550 in the power conversion device 500, when the output voltage is out of the first range, it is determined that the level of the load 900 is sharply reduced from the first level to the second level, the inverter 540 is turned off and then controlled to be restarted (S920).

Then, the control unit 550 in the power conversion device 500, when the inverter 540 is restarted, based on a second gain higher than the first gain before the inverter 540 is turned off, control the inverter 540 to operate It can be done (S925). Accordingly, it is possible to stably operate the inverter 540 when restarting according to a sudden load change.

On the other hand, the control unit 550 in the power conversion device 500, after the inverter 540 is restarted, based on the second gain, while driving the inverter 540, the output voltage output from the inverter 540 is in the first range It is determined whether it is within (Vrar) (S930), and when the output voltage output from the inverter 540 is within the first range (Vrar), the inverter 540 can be controlled to operate based on the first gain. There is (S935). Accordingly, it is possible to stably operate the inverter 540 when restarting according to a sudden load change.

10A to 10B are diagrams referred to in the description of FIG. 9 .

First, FIG. 10A illustrates a waveform Vacma of the output voltage of the inverter 540 .

Referring to the drawings, it is exemplified that the output voltage of the inverter 540 is maintained within a first range Vrar between LVP and -LVP during the Pa period.

For example, when the level of the load 900 in the internal power grid of FIG. 8A is the first level, the output voltage of the inverter 540 may be maintained within the first range Vrar as shown in FIG. 10A .

On the other hand, at the time Tm1a, when the level of the load 900 in the internal power grid is lowered to the second level, which is much smaller than the first level, since the filter is not disposed at the output terminal of the inverter 540, the output voltage of the inverter 540 will rise sharply.

In the figure, it is exemplified that the level of the output voltage of the inverter 540 at the time Tm1a is out of the first range Vrar. In particular, in the Ara region, it is exemplified that the level of the output voltage of the inverter 540 is out of the first range Vrar.

That is, during the Pb period, the level of the output voltage of the inverter 540 may be out of the first range Vrar.

When the output voltage output from the inverter 540 rises and is out of the first range Vrar at the time Tm1a, the controller 550 turns off the inverter 540 and then controls the inverter 540 to be restarted.

Accordingly, after the Pb period and during the Pc period, the level of the output voltage of the inverter 540 may be maintained within the first range Vrar again.

Meanwhile, when the inverter 540 is restarted during the Pb period, the controller 550 may control the inverter 540 to operate based on a second gain higher than the first gain before the inverter 540 is turned off. Accordingly, it is possible to stably operate the inverter 540 when restarting according to a sudden load change.

On the other hand, the controller 550 drives the inverter 540 based on the second gain after the inverter 540 is restarted, and in the Pc period, the output voltage output from the inverter 540 is within the first range (Vrar). , the inverter 540 may be controlled to operate based on the first gain. Accordingly, it is possible to stably operate the inverter 540 when restarting according to a sudden load change.

Meanwhile, at the time Tm1a, in a state in which the output voltage is out of the first range Vrar, as the peak of the output voltage increases, the level of the second gain increases after the inverter 540 is restarted. can be controlled Accordingly, when restarting according to a sudden load change, the inverter 540 can be operated quickly and stably.

Meanwhile, at the time Tm1a, in a state in which the output voltage is out of the first range Vrar, as the peak of the output voltage increases, after restarting the inverter 540 , the second gain based on the second gain The driving period Pb may be controlled to increase. Accordingly, when restarting according to a sudden load change, the inverter 540 can be operated quickly and stably.

On the other hand, when the output voltage output from the inverter 540 is within the first range Vrar after restarting the inverter 540 , that is, during the Pc period, the control unit 550 may Based on the gain equal to 1 gain, the inverter 540 may be controlled to operate. Accordingly, it is possible to stably operate the inverter 540 when restarting according to a sudden load change.

On the other hand, when the output voltage output from the inverter 540 is within a predetermined range after the restart of the inverter 540, the control unit 550, based on a gain lower than the gain after the restart of the inverter 540, the inverter ( 540) can be controlled to operate.

That is, it is possible to control so that the gain during the Pc period is lower than the gain during the Pb period. Accordingly, it is possible to stably operate the inverter 540 when restarting according to a sudden load change.

On the other hand, the control unit 550, when the output voltage output from the inverter 540 rises and out of the first range Vrar in a state in which the system is out of power, turns off the inverter 540 and then restarts the control. can Accordingly, it is possible to stably operate the inverter 540 when restarting according to a sudden load change.

Meanwhile, the above-described first gain, second gain, and the like may be gains used in the voltage controller 920 of FIG. 6 .

That is, when the inverter 540 is restarted, the voltage controller 920 may generate a current command value for controlling the converter 530 based on a second gain higher than the first gain before the inverter 540 is turned off. .

10B illustrates the waveform Pma of the output power of the inverter 540 .

Referring to the drawing, it is exemplified that the output power of the inverter 540 is out of the second range Prar between LP and -LP before the time Tm2. Accordingly, the output power is stably output.

On the other hand, when the level of the load 900 in the internal power grid drops to a second level that is much smaller than the first level at the time Tm2, the filter is not disposed at the output terminal of the inverter 540, so the output power of the inverter 540 falls rapidly.

Accordingly, when the output power output from the inverter 540 increases at the time Tm2 and is within the second range Prar, the controller 550 may turn off the inverter 540 and then restart the inverter 540 . Accordingly, it is possible to stably operate the inverter 540 when restarting according to a sudden load change.

11 is a circuit diagram of a power conversion device according to an embodiment of the present invention, and FIGS. 12A to 14C are diagrams referenced in the description of the power conversion device of FIG. 11 .

Referring to FIG. 11 , the power conversion device 500 according to an embodiment of the present invention may include an inverter 540 , a control unit 550 for controlling the inverter 540 , and a filter unit 570 .

The inverter 540 includes a fourth leg including a seventh switching element SW1 and an eighth switching element SW2 connected in series with each other, and a ninth switching element SW3 and a tenth element connected in series with each other. A fifth leg including the switching element SW4 may be provided. At this time, the fourth leg and the fifth leg are connected in parallel to each other.

Meanwhile, according to an embodiment of the present invention, the control unit 550 performs asynchronous pulse width variable control in which the switching frequencies of the fourth leg and the fifth leg of the inverter 540 are different, and the inverter output At the zero crossing point of the voltage, the switching elements SW3 and SW4 in the fifth leg are turned off, and the seventh switching element SW1 or the eighth switching element SW2 is controlled to switch.

On the other hand, the control unit 550, the seventh switching element (SW1) and the seventh switching element (SW1) in the fourth leg (legd) than the switching frequency of the ninth switching element (SW3) and the tenth switching element (SW4) in the fifth leg (legd) 8 The switching frequency of the switching element SW2 may be controlled to be larger.

Meanwhile, the controller 550 may control the switching frequencies of the ninth switching element SW3 and the tenth switching element SW4 in the fifth leg to be the same as the switching frequency.

For example, the switching frequency of the fourth leg is a high-speed switching frequency, and may be several KHz to several hundreds of KHz higher than the system frequency of 50 Hz or 60 Hz.

Meanwhile, the switching frequency of the fifth leg, as the magnetic flux switching frequency, may be 50 Hz or 60 Hz, which is a system frequency.

On the other hand, according to the embodiment of the present invention, while performing asynchronous pulse width variable control, near the zero crossing point of the inverter output voltage, peak current generation according to the turn-off of the switching elements SW1 to SW4 of the inverter 540, etc. In order to prevent this, the switching elements SW3 and SW4 in the fifth leg are turned off, and the seventh switching element SW1 or the eighth switching element SW2 is controlled to switch.

Accordingly, it is possible to improve the quality of the output AC power. In particular, it is possible to improve the current distortion of the AC power output while performing the asynchronous pulse width variable control. In addition, it is possible to perform power factor control while performing asynchronous pulse width variable control.

Meanwhile, the controller 550 performs asynchronous pulse width variable control in which the switching frequencies of the fourth leg and the fifth leg of the inverter 540 are different, and the inverter output voltage is changed from positive polarity to negative polarity. At the changing zero crossing time point (Tzca in FIGS. 12A and 12B or Tzcb in FIGS. 13A and 13B ), the switching elements SW3 and SW4 in the fifth leg are turned off, and the seventh switching element SW1 or the second switching element SW1 is turned off. 8 switching element SW2 may be controlled to switch. Accordingly, it is possible to improve the current distortion of the AC power output while performing the asynchronous pulse width variable control.

Meanwhile, the control unit 550 controls the inverter 540 to perform the reflux mode during a period between a first time point when the tenth switching element SW4 is turned off and a second time point when the ninth switching element SW3 is turned on. can be controlled Accordingly, it is possible to improve the current distortion of the AC power output while performing the asynchronous pulse width variable control.

On the other hand, the control unit 550, during a period between the first time when the tenth switching element (SW4) is turned off and the second time when the ninth switching element (SW3) is turned on, the seventh switching element (SW1) or the eighth switching element (SW1) The switching element SW2 may be controlled to switch. Accordingly, it is possible to improve the current distortion of the AC power output while performing the asynchronous pulse width variable control.

12A illustrates a case in which the current Igxa output from the inverter 540 is slower than the voltage Vgxa.

Meanwhile, as shown in the drawing, the output voltage Vgxa output from the inverter 540 may cross zero at Zca. In particular, the point Zca corresponds to a point in time when the output voltage Vgxa output from the inverter 540 has a positive voltage and is changed to a negative voltage.

The inverter output voltage detection unit F may detect a voltage vc3 output from the inverter 540 , and the control unit 550 includes a particularly zero crossing point Zca among the voltages vc3 output from the inverter 540 . ) can be detected.

12B is a diagram illustrating switching waveforms of switching elements of the inverter 540 when the current output from the inverter 540 is ground.

Referring to the drawing, when the current output from the inverter 540 is grounded, the controller 550 performs a ninth switching from a first time point Taa when the tenth switching element SW4 is turned off, as shown in FIG. 12B . During the period Pda between the second time points Tbb in which the element SW3 is turned on, the seventh switching element SW1 is turned on to control the switching.

In the drawing, at the time Ta1 of the period Pda between the first time point Taa and the second time point Tbb at which the ninth switching element SW3 is turned on, the seventh switching element SW1 is turned on to switch example of doing

According to this, compared with FIG. 3B , during the Pda period in which the switching in the inverter 540 is not performed, the seventh switching element SW1 is turned on and switched.

Meanwhile, during the Pd4a and Pd3a periods corresponding to the power supply mode for outputting AC power to the outside, a current path is formed through the switching element turned on according to the switching of each switching element.

And, during the Pda period, the reflux mode is performed, as shown in FIG. 12c or 12d , through the diode element D3 connected in parallel to the seventh switching element SW1 and the ninth switching element SW3, the first A current path path1 may be formed.

That is, the control unit 550, as shown in FIG. 12A , when the current output from the inverter 540 is grounded, the seventh switching element SW1 and the diode element D3 connected in parallel to the ninth switching element SW3. ), it is possible to control the formation of the first current path path1.

Accordingly, by performing power factor control while performing asynchronous pulse width variable control, it is possible to improve current distortion of the output AC power as shown in FIG. 12E . In particular, it is possible to improve the current distortion of the output AC power during the Pda section.

12E illustrates that the peak current is removed from the waveform of the ground current Iga and the voltage waveform Vga so that the current quality and the voltage quality are improved.

Meanwhile, when the current output from the inverter 540 is grounded, the controller 550 may control the eighth switching element SW2 to be turned off at the first time point Taa. Accordingly, it is possible to improve the current distortion of the output AC power by performing the power factor control while performing the asynchronous pulse width variable control.

On the other hand, the control unit 550, during the period Pda between the first time point Taa when the tenth switching element SW4 is turned off and the second time point Tbb when the ninth switching element SW3 is turned on, the second The switching frequency of the seventh switching element SW1 or the eighth switching element SW2 is controlled to be greater than the switching frequencies of the ninth switching element SW3 and the tenth switching element SW4 in the fifth leg can do. Accordingly, it is possible to improve the current distortion of the AC power output while performing the asynchronous pulse width variable control.

On the other hand, the power conversion device 500 according to the embodiment of the present invention, as shown in Figure 2, an output voltage detection unit (F) for detecting the output voltage (Vc3) output from the inverter 540, the inverter ( It may further include an output current detection unit (E) for detecting the output current (Ic3) output from the 540 (E). Accordingly, it is possible to perform power factor control while performing asynchronous pulse width variable control.

Meanwhile, the controller 550 may calculate a power factor based on the output voltage and the output current. Accordingly, it is possible to perform power factor control while performing asynchronous pulse width variable control.

For example, the controller 550 may perform power factor adjustment for adjusting a power factor between a voltage output from the inverter 540 and a current during the Pd4a and Pd3a sections.

Specifically, during the Pd4a period, the tenth switching element SW4 is turned on, the ninth switching element SW3 is turned off, and the seventh switching element SW1 and the eighth switching element SW2 are alternately switched.

Meanwhile, during the Pd3a period, the tenth switching element SW4 is turned off, the ninth switching element SW3 is turned on, and the seventh switching element SW1 and the eighth switching element SW2 are alternately switched.

Meanwhile, the controller 550 may perform power factor adjustment for adjusting a power factor between a voltage output from the inverter 540 and a current during the Pda period.

Meanwhile, the controller 550 may vary the switching frequencies of the seventh switching element SW1 and the eighth switching element SW2 in the fourth leg according to the calculated power factor. Accordingly, it is possible to perform power factor control while performing asynchronous pulse width variable control.

Meanwhile, according to the calculated power factor, the controller 550 is configured to be configured for a period between a first time point Taa when the tenth switching element SW4 is turned off and a second time point Tbb when the ninth switching element SW3 is turned on. The switching timing of the seventh switching element SW1 or the eighth switching element SW2 in Pda may be varied.

For example, the controller 550 may control the switching timing Ta1 of the seventh switching element SW1 or the eighth switching element SW2 to be closer to Taa as the calculated power factor is smaller. Accordingly, it is possible to improve the current distortion of the output AC power by performing the power factor control while performing the asynchronous pulse width variable control.

13A illustrates a case in which the current Igba output from the inverter 540 leads the voltage Vgba.

Meanwhile, as shown in the drawing, the output voltage Vgba output from the inverter 540 may cross zero at Zcb. In particular, the point Zcb corresponds to a point in time when the output voltage Vgba output from the inverter 540 has a positive polarity voltage and is changed to a negative polarity voltage.

The inverter output voltage detection unit F may detect a voltage vc3 output from the inverter 540 , and the control unit 550 may specifically include a zero crossing point Zcb among the voltages vc3 output from the inverter 540 . ) can be detected.

13B is a diagram illustrating switching waveforms of switching elements of the inverter 540 when the current output from the inverter 540 is forward.

Referring to the drawing, when the current output from the inverter 540 is leading, the controller 550 performs a ninth switching from a first time point Tba when the tenth switching element SW4 is turned off, as shown in FIG. 13B . During the period Pdb between the second time points Tbb in which the element SW3 is turned on, the eighth switching element SW2 is turned on to control the switching.

In the drawing, from the first time point Tba to the time Tb1 in the section Pdb between the second time point Tbb at which the ninth switching element SW3 is turned on, the eighth switching element SW2 continues to switch exemplify

According to this, compared to the conventional 3b, the eighth switching element SW2 switches during the Pdb period in which the switching in the inverter 540 is not performed.

Meanwhile, during the Pd4b and Pd3b periods corresponding to the power supply mode for outputting AC power to the outside, a current path is formed through the switching element turned on according to the switching of each switching element.

And, during the Pdb period, the reflux mode is performed, as shown in FIG. 13c or 13d , through the diode element D4 connected in parallel to the eighth switching element SW2 and the tenth switching element SW4, the second A current path (path2) may be formed.

That is, the control unit 550, as shown in FIG. 13A , when the current output from the inverter 540 is forward, the eighth switching element SW2 and the diode element D4 connected in parallel to the tenth switching element SW4. ), it is possible to control the formation of the second current path (path2).

Accordingly, by performing power factor control while performing asynchronous pulse width variable control, it is possible to improve current distortion of the output AC power as shown in FIG. 13E . In particular, it is possible to improve the current distortion of the output AC power during the Pdb period.

13E illustrates that the peak current is removed from the waveform of the leading current Igb and the voltage waveform Vgb to improve the current quality and the voltage quality.

Meanwhile, when the current output from the inverter 540 is leading, the controller 550 may control the seventh switching element SW1 to be turned on and switched at the second time point Tbb. Accordingly, it is possible to improve the current distortion of the output AC power by performing the power factor control while performing the asynchronous pulse width variable control.

On the other hand, the control unit 550, during the period Pdb between the first time point Tba when the tenth switching element SW4 is turned off and the second time point Tbb when the ninth switching element SW3 is turned on, the second The switching frequency of the seventh switching element SW1 or the eighth switching element SW2 is controlled to be greater than the switching frequencies of the ninth switching element SW3 and the tenth switching element SW4 in the fifth leg can do. Accordingly, it is possible to improve the current distortion of the AC power output while performing the asynchronous pulse width variable control.

Meanwhile, the control unit 550 may calculate a power factor based on the output voltage from the output voltage detection unit F and the output current from the output current detection unit E . Accordingly, it is possible to perform power factor control while performing asynchronous pulse width variable control.

For example, the controller 550 may perform power factor adjustment for adjusting a power factor between a voltage output from the inverter 540 and a current during the Pd4b and Pd3b sections.

Specifically, during the Pd4b period, the tenth switching element SW4 is turned on, the ninth switching element SW3 is turned off, and the seventh switching element SW1 and the eighth switching element SW2 are alternately switched.

Meanwhile, during the Pd3b period, the tenth switching element SW4 is turned off, the ninth switching element SW3 is turned on, and the seventh switching element SW1 and the eighth switching element SW2 are alternately switched.

Meanwhile, the controller 550 may perform power factor adjustment for adjusting a power factor between a voltage output from the inverter 540 and a current during the Pdb period.

Meanwhile, the controller 550 may vary the switching frequencies of the seventh switching element SW1 and the eighth switching element SW2 in the first leg according to the calculated power factor. Accordingly, it is possible to perform power factor control while performing asynchronous pulse width variable control.

Meanwhile, according to the calculated power factor, the control unit 550 is configured to perform a period between a first time point Tba when the tenth switching element SW4 is turned off and a second time point Tbb when the ninth switching element SW3 is turned on. The switching timing of the seventh switching element SW1 or the eighth switching element SW2 in Pdb may be varied.

For example, the controller 550 may control the turn-off timing Tb1 of the seventh switching element SW1 or the eighth switching element SW2 to be closer to Tbb as the calculated power factor is smaller. Accordingly, it is possible to improve the current distortion of the output AC power by performing the power factor control while performing the asynchronous pulse width variable control.

14A to 14C are diagrams illustrating a method of operating a power conversion device according to an embodiment of the present invention.

Referring to FIG. 14A , the power conversion device 500 according to an embodiment of the present invention may include an inverter 540, and the current and voltage output from the inverter 540 are connected to an external grid or an internal power grid. It can be output as a connected load.

14B is a diagram illustrating a zero crossing point Zc of a voltage output from the inverter 540 .

The controller 550 may control so that power factor control is performed in a section Pdc including the zero crossing point Zc of the inverter output voltage, and high-speed switching is performed near the zero crossing point Zc of the inverter output voltage. .

In particular, the controller 550 performs asynchronous pulse width variable control in which the switching frequencies of the fourth leg and the fifth leg of the inverter 540 are different, and the tenth switching element SW4 is turned off. During the period between the first time point (Taa in FIG. 12A ) and the second time point Tab at which the ninth switching element SW3 is turned on, the switching frequency of the fifth leg is before the first time point Taa It can be controlled to be higher than the switching frequency of the fifth leg of

That is, as shown in FIG. 14C , during the Pma section before the first time point Taa and the Pmb section after the second time point Tab, the control unit 550 controls the fourth leg and fifth leg of the inverter 540 . Asynchronous pulse width variable control with different leg switching frequencies is possible.

In this case, the switching frequency of the fourth leg may be between several KHz and several hundred KHz, and the switching frequency of the fifth leg may be the system frequency.

Meanwhile, during the period Po1 including the zero-crossing time point Tzc, the controller 550 performs power factor control while changing the switching frequency of the fifth leg in the Pma period before the first time point Taa. , may be controlled to be higher than the switching frequency during the Pmb period after the second time point Tab.

For example, the controller 550 may control the switching frequency of the fifth leg to be between several KHz and several hundred KHz during the period Po1 including the zero crossing time point Tzc. Accordingly, it is possible to improve the current distortion of the output AC power.

In addition, during the section Po1 including the zero crossing time point Tzc, it is possible to form a bidirectional current path in the system direction as well as in the inverter direction.

15 is a diagram referenced to explain a case in which the full-bridge switching unit 532 operates in the buck mode.

Referring to the drawings, (a) of FIG. 15 shows a dc terminal voltage waveform Vdca, which is a voltage across both ends of the dc terminal.

FIG. 15B illustrates switching control signals SQ1 and SQ4 applied to gates of the first switching element Q1 and the fourth switching element Q4.

FIG. 15C illustrates switching control signals SQ2 and SQ3 applied to gates of the second switching element Q2 and the third switching element Q3.

FIG. 15D illustrates a voltage waveform VQ4 at both ends and a current waveform IQ4 of the fourth switching element Q4.

In the case of the buck mode, the first switching element (Q1) and the fourth switching element (Q4), the second switching element (Q2) and the third switching element (Q3) in the full-bridge switching unit 532 are alternately turned on However, as shown in the figure, some overlap may occur due to a phase shift.

That is, the phase difference between the first switching element Q1 and the fourth switching element Q4 is not fixed by 180 degrees, but a phase or turn-on timing may be varied by a phase shift.

In the drawing, it is illustrated that the phase difference between the first switching element Q1 and the fourth switching element Q4 is DLa.

On the other hand, the control unit 550, in the case of the buck mode, may operate the full-bridge switching unit 532 at the maximum switching frequency, and may vary the phase difference (DLa) of the switching elements in the full-bridge switching unit 532.

On the other hand, the control unit 550, the voltage across the dc end is equal to or greater than the target voltage, the greater the difference between the voltage across the dc end and the target voltage, the greater the phase difference (DLa) of the switching element in the full bridge switching unit 532 You can control it to grow.

In particular, the controller 550 may control the phase difference DLa between the first switching element Q1 and the fourth switching element Q4 to increase as the difference between the voltage across the dc terminal and the target voltage increases. have.

On the other hand, the control unit 550, in the case of the buck mode, the turn-on timing of the fourth and third switching elements (Q4, Q3) in the full-bridge switching unit 532, the first and second switching elements (Q1, Q2) ) can be controlled to be delayed than the turn-on timing. Accordingly, it is possible to vary the dc terminal voltage (Vdc).

For example, when the first and fourth switching elements Q1 and Q4 are turned on, current flows, so that the resonance capacitor Cr and the resonance inductor Lr resonate.

Thereafter, when the fourth switching element Q4 is turned off and the third switching element Q3 is turned on, the current flowing through the transformer 536 falls to the ground GND or zero, and the converter 530 , the converter operates in a discontinuous mode (DCM Dis Continue Mode) while the secondary-side switch may operate for zero current switching (ZCS Zero Current Switching).

Meanwhile, the switching elements Q9 and Q10 in the half-bridge switching unit 538 may be switched in synchronization with the first and second switching elements Q1 and Q2 in the full-bridge switching unit 532 .

Meanwhile, the controller 550 may control the turn-on timing delay to increase as the voltage across the dc end is equal to or greater than the target voltage and the difference between the voltage across the dc end and the target voltage is greater.

Accordingly, the difference between the voltage across the dc terminal and the target voltage may be reduced, and as a result, a dc terminal voltage waveform Vdca having a small ripple as shown in FIG. 15A may be output.

On the other hand, the zero voltage turn-on switching (705a, 705b) of the switching element in the full-bridge switching unit 532 is performed, and the zero voltage turn-off switching (705a, 705b) is performed at the Ta time point, the Tb time point, and the like. Accordingly, high-efficiency and high-voltage power conversion are possible.

On the other hand, the control unit 550, in the case of the buck mode, the turn-on timing of the fourth and third switching elements (Q4, Q3) in the full-bridge switching unit 532, the first and second switching elements (Q1, Q2) ) can be controlled to be delayed than the turn-on timing. Accordingly, it is possible to vary the dc terminal voltage (Vdc).

For example, when the first and fourth switching elements Q1 and Q4 are turned on, current flows, so that the resonance capacitor Cr and the resonance inductor Lr resonate.

After that, when the fourth switching element Q4 is turned off and the third switching element Q3 is turned on, the current flowing through the transformer 536 falls to the ground GND or zero, and the converter 530 , the converter operates in a discontinuous mode (DCM Dis Continue Mode) while the secondary side switch may operate for zero current switching (ZCS Zero Current Switching).

Meanwhile, the switching elements S1 and S2 in the half-bridge switching unit 538 may be switched in synchronization with the first and second switching elements Q1 and Q2 in the full-bridge switching unit 532 .

Meanwhile, the controller 550 may control the turn-on timing delay to increase as the voltage across the dc end is equal to or greater than the target voltage and the difference between the voltage across the dc end and the target voltage is greater.

Accordingly, the difference between the voltage across the dc terminal and the target voltage may be reduced, and as a result, a dc terminal voltage waveform Vdca having a small ripple as shown in FIG. 15A may be output.

On the other hand, the zero voltage turn-on switching (705a, 705b) of the switching element in the full-bridge switching unit 532 is performed, and the zero voltage turn-off switching (705a, 705b) is performed at the Ta time point, the Tb time point, and the like. Accordingly, high-efficiency and high-voltage power conversion are possible.

16 is a diagram referenced to explain a case in which the half-bridge switching unit 538 operates in the boost mode.

Referring to the drawings, (a) of FIG. 16 shows a dc terminal voltage waveform (Vdcb) that is a voltage across the dc terminal.

FIG. 16B illustrates switching control signals SQ1 and SQ4 applied to gates of the first switching element Q1 and the fourth switching element Q4.

FIG. 16C illustrates switching control signals SQ2 and SQ3 applied to gates of the second switching element Q2 and the third switching element Q3.

FIG. 16D illustrates switching control signals SS1 and SS2 applied to gates of the fifth switching element S1 and the sixth switching element S10 in the half-bridge switching unit 538 .

FIG. 16E illustrates a voltage waveform VQ4 at both ends and a current waveform IQ4 of the fourth switching element Q4.

On the other hand, the control unit 550, in the case of the boost mode, the first switching element (Q1) and the fourth switching element (Q1) in the full bridge switching unit 532, as shown in FIGS. 16 (b) and 16 (c) ( Q4), the second switching element Q2 and the third switching element Q3 may be controlled to be turned on alternately.

On the other hand, in the case of the boost mode, the control unit 550 may operate the full-bridge switching unit 532 at the minimum switching frequency, and may vary the turn-on duty of the switching element in the half-bridge switching unit 538 . In (d) of FIG. 16 , DLb is exemplified as the turn-on duty.

For example, while the first switching element Q1 and the fourth switching element Q4, the second switching element Q2, and the third switching element Q3 are alternately turned on, the half-bridge switching unit 538 ) is turned on while the duties of the fifth switching element S1 and the tenth switching element S2 are varied.

Meanwhile, while the fifth switching element S1 and the tenth switching element S2 in the half-bridge switching unit 538 are turned on, energy is charged in the resonance inductor Lr. Thereby, the pressure increase is performed.

On the other hand, the control unit 550, the voltage across the dc terminal is less than the target voltage, the greater the difference between the voltage across the dc terminal and the target voltage, the fifth switching element (S1) in the half-bridge switching unit 538, and The turn-on duty DLb of the tenth switching element S2 may be controlled to increase.

On the other hand, the control unit 550, the voltage across the dc terminal is less than the target voltage, the greater the difference between the voltage across the dc terminal and the target voltage, the greater the turn-on duty of the switching element in the half-bridge switching unit 538. can be controlled

Accordingly, the difference between the voltage across the dc terminal and the target voltage may be reduced, and as a result, a dc terminal voltage waveform Vdca having a small ripple as shown in FIG. 16A may be output.

On the other hand, the zero voltage turn-on switching (715a, 715b) of the switching element in the full-bridge switching unit 532 is performed at the time T1 and the time T2, and the zero voltage turn-off switching (715a, 715b) is performed. Accordingly, high-efficiency and high-voltage power conversion are possible.

17 is an exploded perspective view of the solar cell module of FIG. 1A or 1B.

Referring to FIG. 17 , the solar cell module 100 of FIG. 2 may include a plurality of solar cells 130 . In addition, 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, the rear substrate 110 and the second located on the lower surface of the first sealing material (120) A front substrate 160 positioned on the upper surface of the sealing material 150 may be further included.

First, the solar cell 130 is a semiconductor device that converts solar energy into electrical energy, and includes a silicon solar cell, a compound semiconductor solar cell, and a tandem solar cell; It may be a dye-sensitized or CdTe, CIGS type solar cell, a thin film 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 may include 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 the first conductivity type, and a second conductivity type semiconductor layer. an anti-reflection film formed on the second conductivity-type semiconductor layer including at least one opening exposing a partial surface of the , may include 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, the plurality of solar cells 130 may be electrically connected by a ribbon 133 . The ribbon 133 may be bonded to a front electrode formed on the light receiving surface of the solar cell 130 and a rear electrode current collecting electrode formed on the rear surface of another adjacent solar cell 130 .

In the drawing, the ribbon 133 is formed in two rows, and the solar cells 130 are connected in a line by the ribbon 133 to illustrate that the solar cell string 140 is formed.

Accordingly, as described with reference to FIG. 2 , six strings 140a, 140b, 140c, 140d, 140e, and 140f are formed, and each string may include 10 solar cells.

The rear substrate 110, as a back sheet, functions to waterproof, insulate, and block UV rays, and may be a Tedlar/PET/Tedlar (TPT) type, but is not limited thereto. In addition, although the rear substrate 110 is shown in a rectangular shape in FIG. 4 , it may be manufactured in various shapes such as a circular shape or a semi-circular shape depending on the environment in which the solar cell module 100 is installed.

On the other hand, on the rear substrate 110, the first sealing material 120 may be attached to the same size as the rear substrate 110, and a plurality of solar cells 130 on the first sealing material 120 to generate several heat. They may be located adjacent to each other to achieve this.

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

Here, the first sealing material 120 and the second sealing material 150 allow each element of the solar cell to be chemically combined. Various examples of the first sealing material 120 and the second sealing material 150 are possible, such as an ethylene vinyl acetate (EVA) film.

Meanwhile, the front substrate 160 is positioned on the second sealing material 150 to transmit sunlight, and is preferably made of tempered glass to protect the solar cell 130 from external impact. In addition, in order to prevent the reflection of sunlight and to increase the transmittance of sunlight, it is more preferable that the glass is low-iron tempered glass containing less iron.

The power conversion device according to the present invention, and the solar module having the same, the configuration and method of the embodiments described above are not limitedly applicable, but the embodiments are each embodiment so that various modifications can be made All or part of them may be selectively combined and configured.

In addition, although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the present invention belongs without departing from the gist of the present invention as claimed in the claims Various modifications are possible by those of ordinary skill in the art, and these modifications should not be individually understood from the technical spirit or prospect of the present invention.

Claims (20)

a converter for varying the level of the input DC power;
an inverter converting the DC power from the converter into AC power and outputting the AC power converted to an internal power grid or grid;
a control unit for controlling the converter and the inverter; and
The control unit is
When the output voltage output from the inverter rises, out of a first range, the power converter, characterized in that the control to restart after turning off the inverter. According to claim 1,
The control unit is
When the inverter is restarted, based on a second gain higher than the first gain before the inverter is turned off, the inverter is controlled to operate. 3. The method of claim 2,
The control unit is
After restarting the inverter, while driving the inverter based on the second gain, when the output voltage output from the inverter is within the first range, controlling the inverter to operate based on the first gain A power converter characterized by the 3. The method of claim 2,
The control unit is
In a state in which the output voltage is out of the first range, as the peak of the output voltage increases, after restarting the inverter, the level of the second gain is controlled to increase. 3. The method of claim 2,
The control unit is
In a state in which the output voltage is out of the first range, as the peak of the output voltage increases, after restarting the inverter, a second gain driving period based on the second gain is controlled to increase. Device. According to claim 1,
The control unit is
After the inverter is restarted, when the output voltage output from the inverter is within the first range, based on the same gain as the first gain before the inverter is turned off, power conversion, characterized in that the inverter is controlled to operate Device. According to claim 1,
The control unit is
After the restart of the inverter, when the output voltage output from the inverter is within the first range, based on a gain lower than the gain after the restart of the inverter, power conversion device, characterized in that the control to operate the inverter . According to claim 1,
The control unit is
When the output voltage output from the inverter rises and deviates from a first range in a state in which the system is out of power, the inverter is turned off and then restarted. According to claim 1,
The control unit is
When the output power output from the inverter rises and is within a second range, the power conversion device, characterized in that the inverter is turned off and then controlled to be restarted. According to claim 1,
It further comprises; an output voltage detection unit for detecting the output voltage output from the inverter;
The control unit is
Based on the output voltage from the output voltage detection unit, the output voltage output from the inverter rises, the power conversion device, characterized in that it is determined whether out of a first range. According to claim 1,
The control unit is
Based on the output voltage of the inverter, generating a current command value for controlling the converter,
Power conversion device, characterized in that outputting a converter switching control signal for controlling the converter based on the current command value. 12. The method of claim 11,
The control unit is
a voltage controller configured to generate a current command value for controlling the converter based on an output voltage of the inverter and a voltage command value;
Based on the current command value, the converter controller for generating a converter switching control signal for controlling the converter; Power conversion device comprising a. 13. The method of claim 12,
The voltage controller is
When the inverter is restarted, based on a second gain higher than the first gain before the inverter is turned off, a current command value for controlling the converter is generated. According to claim 1,
The converter is
A first leg including a first switching element and a second switching element connected in series with each other, and a second leg including a third switching element and a fourth switching element connected in series with each other, converting an input DC voltage a full-bridge switching unit;
a transformer having an input side connected to an output terminal of the full-bridge switching unit;
and a half-bridge switching unit electrically connected to the output side of the transformer and having a third leg including a fifth switching element and a sixth switching element connected in series with each other. 15. The method of claim 14,
The converter is
Power conversion device further comprising a; resonant inductor connected between the transformer and the half-bridge switching unit. 15. The method of claim 14,
The power conversion device further comprising a; a first capacitor and a second capacitor connected to the dc terminal that is the output terminal of the half-bridge switching unit, which are connected in series with each other. 17. The method of claim 16,
A first node on the output side of the transformer is connected to a resonant inductor,
A second node on the output side of the transformer is connected to a node between the first capacitor and the second capacitor. 15. The method of claim 14,
The inverter is
A fourth leg connected to a dc terminal that is an output terminal of the half-bridge switching unit, the fourth leg including a seventh switching element and an eighth switching element connected in series with each other, and a ninth switching element and a tenth switching element connected in series with each other A power conversion device comprising a fifth leg, and converting the voltage of the dc terminal to output an AC voltage. 19. The method of claim 18,
The inverter is
During the first period, by turning on the seventh switching element and the tenth switching element, the positive polarity dc terminal voltage is converted to a positive voltage and output;
During the second period, by turning on the eighth switching element and the ninth switching element, the power conversion device, characterized in that the output by converting the voltage of the dc terminal of the positive polarity into a voltage of the negative polarity. A photovoltaic module comprising the power conversion device of any one of claims 1 to 19.

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