Power conversion device

Abstract

A power conversion apparatus according to an embodiment of the present invention includes a control unit that monitors an output signal of a photovoltaic module, the output signal being input from the photovoltaic module, in which the control unit controls the photovoltaic module by changing a pulse width of the output signal of the photovoltaic module.

Description

Technical Field

[0001] The present disclosure relates to a power conversion device, and more particularly, to a power conversion device and a photovoltaic system for controlling a photovoltaic module. Background Art

[0002] Photovoltaic power generation, as an environmentally friendly method of power generation, is widely used as an alternative to traditional chemical power generation and nuclear power generation. Photovoltaic power generation can be of a standalone type where a battery is connected to a converter, or a connection type where a battery is connected to the grid. Generally, a standalone power generation configuration includes a photovoltaic cell, a storage battery, and a power conversion device, while a connection type power generation configuration is connected to the commercial power grid so that power can be exchanged with the load grid line.

[0003] Photovoltaic cell components have different maximum power generation and operating points depending on the amount of sunlight, temperature, etc. A module-level power electronics device (MLPE) is used to control the maximum power point (MPPT) of each module so that the photovoltaic cell operates at the maximum power point. However, an independent signal transmission system must be configured to control the photovoltaic module to ensure stable countermeasures in case of an emergency. Summary of the Invention

[0004] Technical Problem

[0005] The technical problem to be solved by the present disclosure is to provide a power conversion device and a photovoltaic system for controlling a photovoltaic module.

[0006] Technical Solution

[0007] To solve this technical problem, a power conversion device according to an embodiment of the present disclosure includes a control unit configured to monitor an output signal of a photovoltaic module input from the photovoltaic module, wherein the control unit controls the photovoltaic module by changing a pulse width of the output signal of the photovoltaic module.

[0008] In addition, the output signal of the photovoltaic module may be an output current of the photovoltaic module.

[0009] In addition, the control unit may receive or block the output signal of the photovoltaic module to form a pulse, and may generate a control signal by changing a reception time or a blocking time.

[0010] In addition, the output signal of the photovoltaic module may include an output voltage or an output power of the photovoltaic module.

[0011] In addition, the photovoltaic module may include a plurality of photovoltaic modules connected in series, and the control unit may stop the operation of at least one of the plurality of photovoltaic modules or bypass it.

[0012] In addition, the varying pulse width can be detected by module-level power electronics (MLPE) included in the photovoltaic module.

[0013] In addition, the MLPE can include a current sensor configured to measure the current of the output sensor.

[0014] The power conversion device can include an inverter configured to convert the DC input from the photovoltaic module into AC, where the control unit can be formed outside the inverter.

[0015] When a rapid shutdown (RSD) situation occurs, the control unit can stop the operation of the photovoltaic module by changing the pulse width.

[0016] To solve the technical problem, a photovoltaic system according to an embodiment of the present disclosure includes at least one photovoltaic module and a power conversion device configured to convert the output of the photovoltaic module and output the converted output to the grid or a load, where the power conversion device controls the photovoltaic module by changing the pulse width of the output signal of the photovoltaic module.

[0017] Advantageous Effects

[0018] According to an embodiment of the present disclosure, the module-level power electronics (MLPE) can be controlled without an independent communication circuit. In addition, since the MLPE can only be controlled by current control, the inverter and the MLPE can be freely compatible. Description of the Drawings

[0019] Figure 1 is a block diagram of a power conversion device according to an embodiment of the present disclosure.

[0020] Figure 2 and Figure 3 is a block diagram of a power conversion device according to a comparative example of the present disclosure.

[0021] Figure 4 is a block diagram of a power conversion device according to an embodiment of the present disclosure.

[0022] Figure 5 and Figure 6 are views for describing a power conversion device according to an embodiment of the present disclosure.

[0023] Figure 7 is a block diagram of a photovoltaic system according to an embodiment of the present disclosure. Detailed Description of the Embodiments

[0024] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0025] However, the technical idea of the present invention is not limited to some embodiments to be described, but can be implemented in various forms, and within the scope of the technical idea of the present invention, one or more of the constituent elements can be selectively combined or replaced between the embodiments.

[0026] In addition, unless clearly defined and described, the terms (including technical terms and scientific terms) used in the embodiments of the present invention can be interpreted as the meanings commonly understood by those skilled in the art, and common terms can be interpreted in consideration of the meaning in the context of the related art, such as the terms defined in a dictionary.

[0027] In addition, the terms used in this specification are for describing the embodiments and are not intended to limit the present invention. In this specification, unless specifically stated in a phrase, the singular form may include the plural form, and when described as "at least one (or more than one) of A, B, and C", it may include one or more combinations of all the combinable ones of A, B, and C.

[0028] [In addition, when describing the components of the embodiments of the present invention, terms such as first, second, A, B, (a), and (b) may be used.

[0029] These terms are only intended to distinguish the components from other components, and these terms do not limit the nature, order, or sequence of the components.

[0030] And when a component is described as "connected", "coupled", or "interconnected" to another component, the component not only directly connects, couples, or interconnects to the other component, but may also include the case of being "connected", "coupled", or "interconnected" due to the presence of one or more other components between the other components.

[0031] In addition, when described as "formed on" or "disposed on" the "upper (above)" or "lower (below)" of each component, the "upper (above)" or "lower (below)" not only includes the case where the two components are in direct contact, but also includes the case where one or more other components are formed or disposed between the two components. In addition, the expression of "upper (above)" or "lower (below)" not only refers to the upward direction relative to a certain component, but may also include the meaning of the downward direction.

[0032] A modified embodiment according to this embodiment may include some components of each embodiment and some components of other embodiments. That is, the modified embodiment may include one of the various embodiments, but may omit some components and may include some components of the corresponding other embodiments. Or vice versa. The features, structures, effects, etc. described in the embodiments are included in at least one embodiment and are not necessarily limited to one embodiment. In addition, the features, structures, effects, etc. illustrated in each embodiment can be combined, modified, and implemented by those of ordinary skill in the art to which the embodiments belong in other embodiments. Therefore, the content related to such combinations and modifications should be construed as being included within the scope of the embodiments.

[0033] Figure 1 is a block diagram of a power conversion device according to an embodiment of the present disclosure, Figure 2 and Figure 3 is a block diagram of a power conversion device according to a comparative example of the present disclosure, Figure 4 is a block diagram of a power conversion device according to an embodiment of the present disclosure, Figure 5 and Figure 6 is a view for describing a power conversion device according to an embodiment of the present disclosure, and Figure 7 is a block diagram of a photovoltaic system according to an embodiment of the present disclosure.

[0034] The power conversion device 110 according to an embodiment of the present disclosure includes a control unit 114 that monitors an output signal of the photovoltaic module 120 input from the photovoltaic module 120. The control unit 114 controls the photovoltaic module 120 by changing the pulse width of the output signal of the photovoltaic module 120.

[0035] The power conversion device 110 according to an embodiment of the present disclosure may be an inverter. In a photovoltaic system, the power conversion device 110 may be an inverter that receives voltage or current from the photovoltaic module 120 or the module-level power electronics device (MLPE) 121 and converts the voltage required by the power grid 130 or the load 140.

[0036] The output of the photovoltaic module 120 may be input through the input unit 111. The input unit 111 receives the voltage generated by the photovoltaic module 120 or is connected to the MLPE 121 that optimizes the voltage of the photovoltaic module 120, and then receives the voltage from the MLPE 121. The maximum power point of the photovoltaic cells of the photovoltaic module 120 varies according to the amount of sunlight, temperature, etc. The module-level power electronics device (MLPE) may be used to perform maximum power point tracking (MPPT) control for each module so that the photovoltaic cells operate at the maximum power point. The power conversion device connected to the photovoltaic module 120 on which the MLPE 121 is installed receives the voltage through the MLPE 121.

[0037] The power conversion unit 112 converts the output signal of the photovoltaic module input to the input unit 111. The input signal is converted into a signal required by the power grid 130 or the load 140. Here, the output signal of the photovoltaic module can be the output current, output voltage, or output power of the photovoltaic module. The power conversion unit 112 can convert the input voltage, which is a first DC voltage, into a first AC voltage. Here, the first AC voltage can be the rated voltage of the power grid 130 or a voltage suitable for the load 140. Here, the load 140 can be a device driven by the voltage generated by the photovoltaic module. For example, the load 140 can be a building equipped with a photovoltaic module or a household device.

[0038] The power conversion unit 112 can include a DC-DC converter or an inverter. The DC-DC converter can convert the first DC signal into a second DC signal. Here, the input signal input to the input unit 111 can be a first DC voltage, and the DC-DC converter can convert the first DC voltage into a second DC voltage. The first DC voltage can vary according to the power generation level of the photovoltaic module 120 or can vary according to the maximum power point tracking of the MLPE 121. The second DC voltage can be the rated voltage of the power grid 130 or a voltage suitable for the load 140. Here, the load 140 can be a battery, and the second DC voltage can be the rated voltage of the battery.

[0039] The inverter can convert the second DC signal into a first AC signal. The inverter can convert the second DC voltage whose voltage level is converted in the DC-DC converter unit into a first AC voltage according to the voltage form of the power grid 130 and output it to the power grid. Since AC voltage is used in the power grid 130, the DC voltage must be converted into an AC voltage and then output.

[0040] When a battery is connected between the DC-DC converter and the inverter, the voltage generated by the DC-DC converter can be directly output to the power grid 130 through the inverter, and the battery can also be charged with the voltage generated by the DC-DC converter. And if necessary, the voltage of the battery can be converted by the inverter and output to the power grid. This realizes an efficient power supply.

[0041] The output unit 113 can output the voltage converted in the power conversion unit 112 to the power grid 130 or the load 140. The output unit 113 can include a switching unit and can be connected to one of the power grid 130 or the load 140 to output the signal converted in the power conversion unit 112.

[0042] The control unit 114 controls the photovoltaic module 120 by changing the pulse width of the output signal of the photovoltaic module 120. The control unit 114 can control the photovoltaic module 120 by changing the pulse width of the output signal of the photovoltaic module 120 without independent communication.

[0043] As Figure 2 or Figure 3 shown, a separate communication device may be required for communication. Figure 2 is a method using power line communication (PLC communication), which can be composed of a photovoltaic module PV, an MLPE (including a DC-DC converter and a communication receiving unit) installed on the photovoltaic module, a signal transmission unit for communication between power lines, and an inverter. A separate device for transmitting communication signals is required.

[0044] Figure 3 is a method using wireless communication, which can be composed of a photovoltaic module PV, an MLPE (including a DC-DC converter and a communication receiving unit) installed on the photovoltaic module, a wireless signal transmission unit for communication between power lines, and an inverter. This also requires a separate device to transmit communication signals and can be controlled by signals from the transmission unit. In this case, in order to control the MLPE, an independent communication circuit and a signal transmission unit are added, which results in an increase in installation cost, a decrease in efficiency, and power quality problems.

[0045] The control unit 114 can receive or block the output signal of the photovoltaic module 120 to form a pulse, and can generate a control signal by changing the reception time or the blocking time. As Figure 5 shown, the control unit 114 can generate a pulse 300 and control the pulse width. The control unit 114 can receive or block the output signal of the photovoltaic module 120 to form a pulse 300, and can generate a control signal by changing the blocking time 310 or the reception time 320. The blocking time 310 represents 0, the reception time 320 represents 1, and the blocking time 310 and the reception time 320 can represent a signal value per unit time. For example, when forming a pulse with a unit time of 1 second, a blocking time of 2 seconds, and a reception time of 3 seconds, a signal of 00111 can be displayed. In addition, various signals can be generated by using the pulse width change. In addition to the pulse width, various signals can also be generated by using the change in pulse size or by using the width and size of the pulse.

[0046] The power conversion device 110 can receive the output from the photovoltaic module 120, and the photovoltaic module 120 outputs power to the power conversion device 110 only when the power line is connected to the power conversion device 110. When the connection to the power conversion device 110 is cut off, the output from the photovoltaic module 120 to the power conversion device 110 is cut off. Utilizing this, the control unit 114 can generate pulses (square waves) by repeatedly disconnecting and connecting to the photovoltaic module 120.

[0047] In this way, when the control unit 114 changes the width of the generated pulses, the output side of the photovoltaic module 120 can output or block signals. The photovoltaic module 120 can detect the output signals, detect the signals from the control unit 114, and operate accordingly.

[0048] The changing pulse width can be detected in the MLPE 121 included in the photovoltaic module 120. The MLPE 121 can include a current sensor for measuring the output current. The MLPE 121 can be connected to the photovoltaic module 120 and can be connected to the power conversion device 110. It can include an input current sensor and an output current sensor. The input current sensor is connected to the photovoltaic module 120 to measure the input current input from the photovoltaic module 120, and the output current sensor is connected to the power conversion device 110 to measure the output current output to the power conversion device 110.

[0049] The photovoltaic module 120 can include a plurality of photovoltaic modules connected in series, and each photovoltaic module 120 can include an MLPE 121. The plurality of photovoltaic modules are connected in an array form, and the entire MLPE 121 forming the array is connected to an inverter which is the power conversion device 110. Using the current sensor of the MLPE 121, the input or output current information can be monitored in real time, and the inverter can control the input current in the form of a square wave under specific circumstances. The MLPE 121 can monitor the width of a specific current square wave and operate accordingly, thereby achieving operation control such as operation stop or bypass.

[0050] The control unit 114 can stop the operation or bypass at least one of the plurality of photovoltaic modules. The plurality of photovoltaic modules 120 can be connected in series to receive the same control signal. Each of the plurality of photovoltaic modules 120 can be assigned an identification number, and the control unit 114 can change the pulse width according to the signal differentiating the identification numbers, thereby controlling only the operation of the corresponding photovoltaic module 120.

[0051] As Figure 6 shown, the plurality of photovoltaic modules 120 and the MLPE 121 respectively installed thereon can be connected in series to form an array. The inverter which is the power conversion device 110 can generate pulses and can control the MLPE by changing the width of the pulses.

[0052] When a fast turn-off (RSD) situation occurs, the control unit 114 can stop the operation of the photovoltaic module 120 by changing the pulse width. The control unit 114 can monitor the photovoltaic module 120, and when an abnormal situation occurs, the control unit 114 can change the pulse width to stop the operation of the photovoltaic module 120. When an input signal in an abnormal range is input to the input unit 111, the control unit 114 can operate to quickly block the input signal. The input current or voltage input to the input unit 111 can be monitored, and when the range of the input signal is outside the abnormal range, the input can be discharged.

[0053] When an abnormality such as a fire occurs in the photovoltaic module 120, the level of the input current or voltage is reduced. Therefore, when an input current or input voltage within the abnormal range is input, the input to the photovoltaic module 120 may be quickly blocked. When a fire occurs, firefighters and other workers may approach the photovoltaic panel, but due to the high residual voltage, there is a risk of electric shock. By quickly reducing the residual voltage, the risk of electric shock can be eliminated.

[0054] The control unit 114 can be formed outside the inverter 112, and the inverter 112 converts the DC input from the photovoltaic module into AC. The control unit 114 can be formed in a standby box connected to the inverter or DC-DC converter of the battery.

[0055] Figure 7 It is a block diagram of a photovoltaic system 200 according to an embodiment of the present disclosure. Figure 7 The detailed description of each component of the photovoltaic system 200 corresponds to Figures 1 to 6 the detailed description of the power conversion device, so any repeated description thereof is omitted.

[0056] The photovoltaic system 200 according to an embodiment of the present disclosure includes at least one photovoltaic module 120 and a power conversion device 110. The power conversion device 110 converts the output of the photovoltaic module 120 and outputs the converted output to the power grid 130 or the load 140, and the power conversion device 110 controls the photovoltaic module 120 by changing the pulse width of the output signal of the photovoltaic module 120.

[0057] The photovoltaic module 120 may include an MLPE 121 that optimizes the voltage of the photovoltaic module 120. The input unit 111 can be connected to the MLPE 121 to receive an input signal. The power conversion module 110 may include a control unit 114, and the control unit 114 controls the photovoltaic module 120 by changing the pulse width of the output signal of the photovoltaic module 120 according to the state of the input signal.

[0058] The control unit 114 can monitor the input current. When the input current is lower or higher than the first voltage current, the control unit 114 can stop operating the photovoltaic module 120 and operate the voltage discharge unit.

[0059] The features, structures, effects, etc. described in the above embodiments are included in at least one embodiment and are not necessarily limited to one embodiment. In addition, the features, structures, effects, etc. shown in each embodiment can be combined, modified, and implemented by those of ordinary skill in the art to which the embodiments belong in other embodiments. Therefore, the content related to such combinations and modifications should be construed as being included within the scope of the embodiments.

[0060] Those skilled in the art related to this embodiment will understand that the above description can be implemented in a modified form without departing from its basic features. Therefore, the disclosed method should be considered from an illustrative rather than a restrictive perspective. The scope of the present invention is indicated by the claims rather than the above description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims

1. A power conversion device includes a control unit configured to monitor an output signal of a photovoltaic module, the output signal being input from the photovoltaic module. Among them, The control unit controls the photovoltaic module by changing a pulse width of the output signal of the photovoltaic module.

2. The power conversion device according to claim 1, wherein The output signal of the photovoltaic module is an output current of the photovoltaic module.

3. The power conversion device according to claim 1, wherein, The control unit receives or blocks the output signal of the photovoltaic module to form a pulse, and generates a control signal by changing a reception time or a blocking time.

4. The power conversion device according to claim 1, wherein, The output signal of the photovoltaic module includes an output voltage or an output power of the photovoltaic module.

5. The power conversion device according to claim 1, wherein, The photovoltaic module includes a plurality of photovoltaic modules connected in series, and wherein the control unit stops the operation of at least one of the plurality of photovoltaic modules or bypasses it.

6. The power conversion device according to claim 1, wherein The changed pulse width is detected by a module-level power electronics device (MLPE) included in the photovoltaic module.

7. The power conversion device according to claim 6, wherein, The MLPE includes a current sensor configured to measure an output sensor.

8. The power conversion device according to claim 1, including an inverter configured to convert a DC current from the photovoltaic module into an AC current. Among them, The control unit is formed outside the inverter.

9. The power conversion device according to claim 1, wherein, When a rapid shutdown (RSD) situation occurs, the control unit stops the operation of the photovoltaic module by changing the pulse width.

10. A photovoltaic system includes: at least one photovoltaic module; and a power conversion device configured to convert an output of the photovoltaic module and output the converted output to a power grid or a load. wherein the power conversion device controls the photovoltaic module by changing a pulse width of an output signal of the photovoltaic module.

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