Power conversion device with multi-stage structure

Abstract

A power conversion device according to an embodiment of the present application includes a plurality of converters connected to a plurality of battery strings, respectively, and a control unit for applying a control signal to each of the plurality of stage converters, wherein the plurality of converters constitute a plurality of stages.

Description

Technical Field

[0001] This invention relates to power conversion equipment, and more specifically, to power conversion equipment and solar modules using multiple converters having a multi-stage structure. Background Technology

[0002] Solar power generation is an environmentally friendly energy source that serves as a replacement for existing chemical or nuclear power generation and is widely distributed. Solar power generation includes stand-alone types where batteries are connected to a converter, and linked types connected to the power grid. Typically, stand-alone systems include solar cells, batteries, power conversion equipment, etc., while grid-connected systems are configured to interact with and supply power to loads via connections to commercial power sources.

[0003] Solar cell modules have different maximum power points (MPPs) depending on factors such as solar irradiance and temperature. To enable solar cells to operate at their MPPs, module-level power electronic devices (MLPEs) with module-based maximum power point tracking (MPPT) control can be used. However, when the solar irradiance and temperature differ for each cell within the module, it is difficult for an MLPE with a single converter to maintain the optimized MPP.

[0004] like Figure 1 As shown, in a method with a single converter, all cells are connected in series and input to an MLPE, which performs maximum power point tracking control on the entire solar cell module. In this case, when the maximum power point of each cell string differs due to variations in solar irradiance within the string, there is a problem that maximum power point tracking control cannot be performed on individual cell strings.

[0005] In addition, such as Figure 2 As shown, in an MLPE method with a single converter, the solar cell module, DC / DC converter, and controller are designed to have the same reference potential (potential). Therefore, when the controller detects the voltage of the solar cell module and the output voltage of the DC / DC converter, the voltage detection circuit can be implemented using only a resistor distribution circuit. However, in a multi-stage MLPE structure, the above method cannot be directly applied.

[0006] Furthermore, MLPE applications with a single converter use the same grounding for the solar cell module, DC / DC converter, controller, and auxiliary power supply. Therefore, as... Figure 3 and Figure 4 As shown, an auxiliary power supply circuit can be configured to receive power from the solar cell module and provide auxiliary power to the converter, controller, etc. However, the above method cannot be directly applied to multi-stage MLPE structures. Summary of the Invention

[0007] [Technical Topic]

[0008] The present invention, intended to solve technical problems, aims to provide a power conversion device and a solar module using multiple converters with a multi-stage structure.

[0009] [Technical Solutions]

[0010] To solve the above-mentioned technical problems, a power conversion device according to an embodiment of the present invention includes: a plurality of converters, each of the plurality of converters being connected to a plurality of battery strings; and a control unit for applying a control signal to each of the plurality of converters, wherein the plurality of converters constitute a multi-stage system.

[0011] In addition, multiple converters can receive control signals and perform maximum power point tracking control.

[0012] In addition, multiple converters can be cascaded.

[0013] In addition, the control unit can monitor at least one of the input signals, output signals, and current flowing in the inductors included in each converter.

[0014] In addition, the control unit can send the monitored information to the outside via power line communication (PLC).

[0015] In addition, the control unit may include: a first control unit for applying control signals to cause the plurality of converters to perform maximum power point tracking control; and a second control unit for monitoring at least one of the following and sending the monitored information to the outside: input signals of the plurality of converters; output signals of the plurality of converters; and current flowing in an inductor included in each converter.

[0016] Furthermore, the control unit can generate a control signal individually for each converter corresponding to each battery string among the multiple converters, based on the output signal of each battery string among the multiple battery strings.

[0017] In addition, control signals for multiple converters can be applied simultaneously.

[0018] In addition, control signals for multiple converters can be applied with a predetermined phase difference.

[0019] Furthermore, the phase difference can vary depending on the number of converters that make up the multi-stage system.

[0020] In addition, the control signal can be a PWM signal used for switching devices included in the converter.

[0021] In addition, each of the multiple battery strings may include at least one or more batteries.

[0022] To address the aforementioned technical problems, a solar module according to an embodiment of the present invention includes: a plurality of battery strings, each battery string including one or more solar cells; a plurality of converters respectively connected to each of the battery strings; and a control unit for monitoring information of each of the plurality of converters and applying control signals to each of the plurality of converters based on the monitored information, wherein the plurality of converters constitute a multi-stage system.

[0023] In addition, multiple converters can be cascaded.

[0024] In addition, the control unit may be an integrated IC: for applying control signals to enable multiple converters to perform maximum power point tracking control; and for monitoring at least one of the input signals and output signals of the multiple converters and the current flow in the inductors included in each converter, and sending the monitored information to the outside.

[0025] [Beneficial Effects]

[0026] According to embodiments of the present invention, the number of control units can be reduced by using an integrated control unit to control multiple converters. Furthermore, each converter can be linked for control, and in addition to maximum power point tracking control, additional functions such as monitoring and communication can be easily implemented using the integrated control unit. Moreover, when detecting voltages with different reference potentials in a multi-stage MLPE, the voltage can be detected using only a resistor distribution circuit in the same manner as conventional methods, without the need for additional devices. Furthermore, when using a multi-stage MLPE, auxiliary power can be smoothly supplied to each DC / DC converter, control circuit, PLC circuit, etc., by implementing an auxiliary power supply circuit. Here, multiple auxiliary power supplies can be generated by applying a single isolated converter to the auxiliary power supply circuit, which helps reduce material costs. Furthermore, when using a multi-stage MLPE, a more stable auxiliary power supply can be obtained by having each DC / DC converter have a separate auxiliary power supply circuit, and when the individual auxiliary power supply circuit is designed as a buck-boost type, material costs can be reduced by cascading a buck regulator and a boost regulator compared to a non-inverting buck-boost converter. Attached Figure Description

[0027] Figures 1 to 4 This is a block diagram of a solar module according to a comparative embodiment of the present invention.

[0028] Figure 5 This is a diagram used to illustrate maximum power point tracking control.

[0029] Figure 6This is a block diagram of a power conversion device according to a first embodiment of the present invention.

[0030] Figure 7 This is a block diagram of a solar module according to a first embodiment of the present invention.

[0031] Figures 8 to 10 This is a view used to illustrate the first embodiment of the present invention.

[0032] Figure 11 This is a block diagram of a power conversion device according to a second embodiment of the present invention.

[0033] Figure 12 This is a block diagram of a solar module according to a second embodiment of the present invention.

[0034] Figure 13 and Figure 14 This is a diagram used to illustrate the second embodiment of the present invention.

[0035] Figure 15 Another embodiment of the power converter according to the second embodiment of the present invention is shown.

[0036] Figure 16 This is a block diagram of a power conversion device according to a third embodiment of the present invention.

[0037] Figure 17 This is a block diagram of a solar module according to a third embodiment of the present invention.

[0038] Figure 18 and Figure 19 Various embodiments of the power conversion device according to the third embodiment of the present invention are shown.

[0039] Figures 20 to 24 Various embodiments of the power conversion device according to the fourth embodiment of the present invention are shown. Detailed Implementation

[0040] In the following, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0041] However, the technical concept of the present invention is not limited to the few embodiments described, but can be implemented in various forms, and within the scope of the technical concept of the present invention, one or more of the constituent elements can be selectively combined or substituted between embodiments.

[0042] Furthermore, unless explicitly defined and described, the terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as meanings that can be normally understood by those skilled in the art, and commonly used terms (e.g., terms defined in dictionaries) may be interpreted taking into account their contextual meaning in the relevant field.

[0043] Furthermore, the terminology used in this specification is for describing embodiments and is not intended to limit the invention. In this specification, unless specifically stated in the 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 of all combinations that can be combined with A, B, and C.

[0044] Furthermore, when describing components of embodiments of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended only to distinguish components from other components, and they do not limit the nature, order, or sequence of the components.

[0045] Furthermore, when a component is described as being “connected,” “coupled,” or “interconnected” to another component, the component is not only directly connected, coupled, or interconnected to the other component, but may also include situations where the component is “connected,” “coupled,” or “interconnected” to another component due to the other component.

[0046] Furthermore, when described as being formed or arranged "above" or "below" in relation to each component, "above" or "below" means not only the case where two components are in direct contact, but also the case where one or more other components are formed or arranged between the two components. Additionally, when expressed as "above" or "below," it can include meanings based on a component that include not only the upward direction but also the downward direction.

[0047] Modified embodiments according to this embodiment may include some components of each embodiment along with some components of other embodiments. That is, a modified embodiment may include one embodiment from various embodiments, but may omit some components, and may include some components of other corresponding embodiments. Alternatively, the reverse may also be true. Features, structures, effects, etc., described in the embodiments are included in at least one embodiment, and are not necessarily limited to one embodiment. Furthermore, the features, structures, and effects shown in each embodiment can be combined or modified by those skilled in the art to which each embodiment pertains relative to other embodiments. Therefore, content related to these combinations and modifications should be interpreted as being included within the scope of the embodiments.

[0048] Figure 6This is a block diagram of a power conversion device according to a first embodiment of the present invention; Figure 7 This is a block diagram of a solar module according to a first embodiment of the present invention; Figures 8 to 10 This is a diagram used to illustrate the first embodiment of the present invention.

[0049] According to a first embodiment of the present invention, a power converter 100 includes a plurality of battery strings 131 to 133, a plurality of converters 111 to 113, and a control unit 120.

[0050] Converters 111 to 113 are respectively connected to multiple battery strings 131 to 133.

[0051] Here, each of the multiple battery strings 131 to 133 may include at least one battery, and when multiple batteries are included, they may be connected in series. Battery strings 131 to 133 may be solar cell strings including solar cells. Solar cell strings may form a solar panel. Solar cells perform solar power generation (PV, photovoltaic) using the photoelectric effect. The photoelectric effect refers to the emission of electrons when light of a specific frequency or higher shines on a specific metallic material. P-type and n-type semiconductors are used to form a PN junction, and current is generated by using electrons generated by the photoelectric effect to produce electricity. Solar cells are formed using silicon and the like, and can be formed in the form of wafers. Solar cells are located in locations that can receive sunlight well, on building exteriors, or on roofs, and use sunlight to generate electricity. In this case, solar cells may be formed by building-integrated photovoltaics (BIPV), which is integrated with the building.

[0052] Since the amount of electricity generated by a single solar cell is insufficient for use in a load or power system, a suitable amount of electricity can be generated by connecting multiple solar cells in series to form a solar cell string (instead of a single solar cell). A solar cell string can be considered the basic unit for generating electricity. Solar panels can be formed by assembling multiple cell strings as basic units.

[0053] like Figure 5As shown, solar cells exhibit different voltage-current characteristics depending on factors such as solar irradiance and temperature, and their maximum power point (MPP) also varies (power generation = voltage × current). Power conversion equipment controls the solar cells to operate at their MPP, which is the point at which the solar cell generates the maximum power under various conditions. This is called maximum power point tracking (MPPT), and using MPPT can improve the efficiency of solar power generation. In solar power generation, based on the characteristics of the relationship between current and voltage, and the relationship between voltage and power, the maximum power may be at approximately 80% of the maximum voltage, rather than the maximum voltage itself. Because this maximum power point constantly changes depending on the magnitude of the voltage and current generated by the solar panel, it is necessary to continuously find the point where the maximum power can be generated. That is, to follow the maximum power rather than the maximum voltage, the magnitude of the voltage and current can be changed to achieve the maximum power. In other words, to increase power, the voltage can decrease and the current can increase, or the voltage can increase and the current can decrease.

[0054] The converter includes multiple converters 111 to 113 corresponding to the number of battery strings 111 to 113. Each of the converters 111 to 113 is connected to a corresponding battery string 131 to 133 to receive power generated from the battery strings 131 to 133, convert the voltage, and output the converted voltage. Figure 1 As shown, when all battery strings are connected in series and a single converter is used to perform maximum power point tracking (MPPT), it is difficult to follow the optimal maximum power point when there are differences in solar irradiance between the battery strings. To achieve effective MPPT, multiple converters, each connected to a specific battery string, are needed to perform MPPT on a per-string basis.

[0055] Converters 111 to 113 are DC-DC converters that can convert a signal with a first voltage into a signal with a second voltage and output the converted signal. Alternatively, they can convert a signal with a first current into a signal with a second current and then output it. In this case, multiple converters 111 to 113 constitute a multi-stage configuration. Multiple converters 111 to 113 can be cascaded to form a multi-stage configuration. Here, cascading means that the output terminals are connected in a multi-stage manner, and the output terminals of the converters are stacked according to the cascading connection to form a multi-stage configuration. A multi-stage configuration refers to a structure that combines the output signals of each converter and outputs a single signal. In this case, as shown... Figure 6 As shown, the (-) terminal of the output terminal of the higher-level converter 111 is sequentially connected to the (+) terminal of the output terminal of the adjacent lower-level converter 112, so that the outputs from the highest-level converter 111 to the lowest-level converter 113 are combined and output as a single signal.

[0056] Control unit 120 applies control signals to each of the plurality of converters 111 to 113. Control unit 120 generates control signals for controlling each of the plurality of converters 111 to 113. The plurality of converters 111 to 113 receive the control signals and perform maximum power point tracking control.

[0057] Each of the multiple converters 111 to 113 receives a control signal from the control unit 120 and performs maximum power point tracking (MPPT) to maximize the power output of the interconnected battery strings 131 to 133. When a solar module consisting of multiple battery strings is formed in a specific area, the MPPT values ​​of the battery strings differ depending on the amount of sunlight they receive. Therefore, each converter performs MPPT control on each battery string to generate maximum power in each string. In this way, optimized MPPT control for each battery string can be achieved.

[0058] In addition to generating control signals for maximum power point tracking control and applying these signals to multiple converters 111 to 113, the control unit 120 can perform other functions. The control unit 120 can monitor at least one of the input and output signals of the multiple converters 111 to 113 and the current flowing in the inductors included in each converter. When generating the control signals for maximum power point tracking control, the control unit 120 monitors the input and output signals of the converters since the input signals of the converters corresponding to the battery string voltages output from battery strings 131 to 133 should be used. At this time, the voltage and current of the input signals and the voltage and current of the output signals can be monitored. Furthermore, the current flowing in the inductors constituting the converters 111 to 113 can be monitored to detect overcurrent flow and can be used for overcurrent protection. In addition, the control unit 120 can monitor various information required for power conversion.

[0059] The control unit 120 can send the monitored information to an upper-level controller or externally. In this case, the control unit 120 can send the monitored information via power line communication (PLC). Power line communication is communication that uses power lines and can perform communication even without a separate communication line. Furthermore, various types of communication, such as wired or wireless, can naturally be used.

[0060] Control unit 120 may include: a first control unit for applying control signals to cause a plurality of converters 111 to 113 to perform maximum power point tracking control; and a second control unit configured to monitor at least one of the input signals and output signals of the plurality of converters and the current flowing in the inductors included in each converter, and to transmit the monitored information to an external source. Control unit 120 may include: a first control unit for performing maximum power point tracking control for each function; and a second control unit for performing monitoring and communication functions. The first and second control units may be formed as a module or as separate modules. The first and second control units may be formed for each functional block or may be formed as an integrated circuit.

[0061] Figure 8 An example implementation of the first embodiment of the present invention is shown, and the power conversion device 100 may be an MLPE. Maximum power point tracking control can be performed for each battery string by using a single control unit to control multiple converters constituting a multi-stage system. Figure 8 As shown, the functions of the MCU (Microcontroller Unit) for monitoring information related to maximum power point tracking (MPPT) and sending the monitored information to the outside world, and the controller for performing MPPT and applying control signals to each converter, can form a control unit. Naturally, separate functional blocks or modules can be formed on a single control unit.

[0062] Figure 9 This implementation includes multiple controllers for controlling the various converters that make up a multi-stage system. Since each converter requires a separate controller, the increased number of controllers leads to increased cost and potentially difficult manufacturing. Furthermore, a separate MCU is also needed for monitoring or communication. Figure 9 Compared to the implementation method, such as in Figure 8 In the implementation, efficient control becomes possible by controlling each of the converters 111 to 113 from a single control unit 120.

[0063] The control unit 120 generates a control signal individually for each of the multiple converters corresponding to each of the multiple battery strings based on the output signal of each of the multiple battery strings, thereby achieving maximum power point tracking for each battery string.

[0064] Converters 111 to 113 may include multiple switching elements, and here, the switching elements may include semiconductor switches such as MOSFETs. The control signal may be a pulse width modulation (PWM) signal used to drive the semiconductor switches in converters 111 to 113. A PWM signal is a signal whose pulse width is adjusted over one cycle. The larger the pulse width, the longer the switching element remains on. That is, the duty cycle increases, and the amount of power sent from converters 111 to 113 to the output increases. Conversely, when the pulse width decreases, the duty cycle decreases, and therefore the amount of power sent from converters 111 to 113 to the output decreases. By adjusting these, voltage and current can be controlled, and in this way, maximum power point tracking control becomes possible. That is, control unit 120 can perform maximum power point tracking control by adjusting the magnitude of the PWM signal.

[0065] When the control unit 120 applies control signals to multiple converters 111 to 113, the control signals can be applied synchronously or with a predetermined phase difference to the multiple converters. Since one control unit 120 controls multiple converters 111 to 113, coordinated control between the individual converters becomes possible. For example, each converter can be applied with a predetermined phase difference. Figure 10 The operation is performed using either the synchronization method or the interleaving method shown. For example... Figure 10 As shown, the synchronous method applies control signals to each converter simultaneously, while in the interleaved method, control signals are applied to each converter with a phase difference. When applying the interleaved method, the operation of the ADC or MCU, which acts as the control unit, is not concentrated at one point but distributed, allowing the application of lower-performance MCUs. The phase difference can vary depending on the number of converters constituting the multi-stage system. For example, when there are three converters, the control signal for each converter can be applied with a phase difference of 120 degrees (360 degrees divided by 3).

[0066] like Figure 7 As shown, the solar module according to the first embodiment of the present invention includes a plurality of battery strings 131 to 133, a plurality of converters 111 to 113, and a control unit 120. Figure 7 The detailed description of the solar module corresponds to the detailed description of the power conversion device according to the first embodiment, and overlapping descriptions will be omitted. Each of the plurality of battery strings 131 to 133 includes one or more solar cells, the plurality of converters 111 to 113 are respectively connected to the battery strings, and the control unit 120 is a control unit for monitoring information of each of the plurality of converters 111 to 113 and applying control signals to each of the plurality of converters 111 to 113 according to the monitored information. The plurality of converters constitute a multi-stage system.

[0067] The cascaded converters 111 to 113 and the control unit 120 may be an integrated IC that applies control signals to cause the converters 111 to 113 to perform maximum power point tracking control, and monitors at least one of the input signals and output signals of the converters 111 to 113 and the current flowing in the inductors included in each converter, and sends the monitored information to the outside.

[0068] Figure 11 This is a block diagram of a power conversion device according to a second embodiment of the present invention; Figure 12 This is a block diagram of a solar module according to a second embodiment of the present invention. Figure 13 and Figure 14 This is a diagram used to illustrate the second embodiment of the present invention.

[0069] The power converter 300 according to the second embodiment of the present invention comprises a plurality of converters 110, a voltage detection unit 140, and a control unit 120. In the detailed description of the power conversion device according to the second embodiment of the present invention, descriptions corresponding to the detailed description of the first embodiment will be omitted. The second embodiment of the present invention mainly describes the configuration for detecting the output voltage of the battery string and the output voltage of the converters in the multi-stage converters 110; therefore, naturally, even if some configuration descriptions are omitted, the configuration according to the embodiment of the present invention may be included.

[0070] Multiple converters 110 are connected to multiple battery strings 130 respectively, and are cascaded to configure multiple stages. The signals output from the multiple converters 110, from the highest level to the lowest level, are combined and output as a single signal.

[0071] The voltage detection unit 140 detects at least one of the input voltage and output voltage of each of the plurality of converters 110. The voltage detection unit 140 is formed at each input terminal and output terminal of the plurality of converters to detect the voltage at each location.

[0072] The voltage detection unit 140 includes two resistors connected in series between the input or output terminal of each converter and ground, and can detect the voltage applied to the node between the two resistors. Figure 13 As shown, at the corresponding location where voltage needs to be measured, i.e., the voltage between the input or output terminal of each converter and ground, it is detected using the voltage divider based on two resistors connected in series.

[0073] The control unit 120 uses the voltage detected by the voltage detection unit 140 to generate and apply control signals for each of the plurality of converters 110. Since the voltage detection unit 140 detects voltages relative to ground, voltages at higher levels (rather than the voltages at the lowest levels with ground as a reference potential) are difficult to detect accurately due to the different reference potentials. Therefore, the control unit 120 receives the voltage detected by each voltage detection unit 140 and uses the relationships at each level to calculate the voltage at each level.

[0074] The control unit 120 calculates the voltage measured in the lowest-level converter as the voltage of the lowest-level converter. Since the reference potential of the lowest-level converter is the same as the reference potential of the voltage detection unit 140, the voltage measured by the lowest-level converter can be used as is. The voltage measured at the output terminal of the highest-level converter can be calculated as the total output voltage. Since the voltage between the output terminal of the highest-level converter and ground is the same as the total output voltage, the voltage measured at the highest level can be used as is without separately detecting the total output voltage.

[0075] For voltages detected at levels other than the lowest level, the voltage at the corresponding level is calculated using the voltage difference measured at the adjacent lower level.

[0076] like Figure 14 As shown, the control unit 120 can calculate the voltage at each stage. For example... Figure 13 As shown, the battery string voltage measured at the input terminals in sequence is V. F1 V F2 and V F3 When the output voltage measured at the output terminal is V B1 V B2 and V B3 At that time, the battery string voltage 1 can be calculated as V. F1 -V F2 The battery string voltage 2 can be calculated as V. F2 -V F3 The battery string voltage 3 can be calculated as V based on its original value. F3 Furthermore, the output voltage 1 can be calculated as V. B1 -V B2 The output voltage 2 can be calculated as V. B2 -V B3 The output voltage 3 can be calculated as V based on its original value. B3 And the total output voltage can be calculated as V B1 Correspondingly.

[0077] The voltage detection unit 140 can also measure the voltage between adjacent input or output terminals, rather than the voltage between the input or output terminal to be measured and ground. In this case, the voltage detection unit 140 may include a reference potential conversion unit that converts the reference potential of the voltage applied to the node between two resistors connected in series between the input terminals of the lower-level converter adjacent to the input or output terminals of each converter into the same reference potential as the control unit. Figure 15 As shown, when measuring voltage, an adjacent lower-level reference level can be used instead of ground level.

[0078] like Figure 15 As shown, an MLPE is a cascaded multi-stage power conversion device, where each stage, consisting of battery strings and corresponding converters, has a different reference potential. That is, the lowest stage has the lowest reference potential, while the higher stages have higher reference potentials. Typically, the reference potential of the lowest stage can be ground. Since the controller, acting as a control unit, is designed to detect only potential differences higher than its own reference potential, in this multi-stage structure, the controller's reference potential is arranged to be the same as the lowest stage's reference potential. In this multi-stage structure and controller arrangement, the controller can detect only voltages with potential differences from its own reference potential. Therefore, the battery string voltage and converter output voltage of the lowest stage, which share the same reference potential, can be detected simply through a resistor distribution circuit. However, since the other higher stages have different reference potentials, a reference potential conversion unit (e.g., a separate circuit) is needed to convert the resistive voltage division at each reference potential into the same reference potential as the controller.

[0079] At this time, since the reference potential in the controller, which serves as the control unit 120, differs from the reference potentials at all levels except the lowest level, the controller includes a reference potential conversion unit for converting the reference potentials therein to the same reference potential. The reference potential conversion unit can make the reference potential equal to the reference potential of the control unit 120 relative to the value of a lower level adjacent to ground. Furthermore, various components or circuits can be used to adjust the reference potential of the voltage detected by the voltage detection unit to match the reference potential of the control unit 120.

[0080] The control unit 120 uses the voltage detected by the voltage detection unit 140 to generate and apply control signals for each of the plurality of converters 110. The control unit 120 can generate control signals individually for each of the plurality of converters corresponding to each of the plurality of battery strings, based on the output signal of each of the plurality of battery strings. The plurality of converters 110 can receive the control signals and perform maximum power point tracking control.

[0081] Control signals for multiple converters can be applied synchronously or with a predetermined phase difference. In this case, the control signal can be a PWM signal for the switching elements included in the converter.

[0082] The control unit 120 monitors at least one of the input and output signals of the multiple converters and the current flowing in the inductors included in each converter, and can transmit the monitored information to the outside via power line communication (PLC).

[0083] like Figure 12 As shown, the solar module according to the second embodiment of the present invention includes a plurality of battery strings 130, a plurality of converters 110, a voltage detection unit 140 and a control unit 120. Figure 12 The detailed description of the solar module corresponds to the detailed description of the power conversion device according to the second embodiment, therefore overlapping descriptions will be omitted.

[0084] Each of the plurality of battery strings 130 includes one or more solar cells, and a plurality of converters 110 are connected to each battery string to form a multi-stage structure. A voltage detection unit 140 detects at least one of the input voltage and output voltage of each of the plurality of converters, and a controller 120 uses the voltage detected by the voltage detection unit 140 to generate and apply control signals for each of the plurality of converters.

[0085] The voltage detection unit 140 includes two resistors connected in series between the input or output terminal of each converter and ground, and detects the voltage applied to the node between the two resistors, wherein the control unit 120 can calculate the voltage measured in each converter by using the voltage difference with the voltage detected in the adjacent lower-level converter.

[0086] Alternatively, the voltage detection unit 140 may include a reference potential conversion unit that converts a reference potential of the voltage applied to a node between two resistors connected in series between the input terminals of a lower-level converter adjacent to the input or output terminals of each converter into the same reference potential as the control unit.

[0087] Figure 16 This is a block diagram of a power conversion device according to a third embodiment of the present invention; Figure 17 This is a block diagram of a solar module according to a third embodiment of the present invention. Figure 18 and Figure 19 Various embodiments of the power conversion device according to the third embodiment of the present invention are shown.

[0088] The power conversion device 500 according to a third embodiment of the present invention includes a plurality of converters 110 and an auxiliary power supply unit 150, and may also include a control unit or a voltage detection unit. In the detailed description of the power conversion device according to the third embodiment of the present invention, descriptions corresponding to the detailed descriptions of the first and / or second embodiments will be omitted. The third embodiment of the present invention focuses on describing the configuration of the auxiliary power supply unit for generating auxiliary power to drive the converters, etc.; therefore, even if descriptions of some configurations are omitted, the configuration according to the embodiment of the present invention can naturally be included.

[0089] Multiple converters 110 are connected to multiple battery strings 130 respectively, and are cascaded to configure multiple stages. The signals output from the multiple converters 110, from the highest level to the lowest level, are combined and output as a single signal.

[0090] The auxiliary power supply unit 150 provides drive power to each of the multiple converters. Figure 3 and Figure 4 The difference lies in Figure 3 and Figure 4 The battery string, converter, controller and auxiliary power supply use the same grounding, while in a multi-stage configuration, the auxiliary power supply unit 150 must provide appropriate auxiliary power for each stage.

[0091] Therefore, the auxiliary power supply unit 150 of the power conversion device according to the third embodiment includes an isolation converter. The primary circuit of the isolation converter receives the voltage of at least one of the output terminals of a plurality of battery strings, the isolation converter outputs a voltage to the secondary circuit according to the voltage of the primary circuit, and the plurality of secondary circuits use the voltage output from the isolation converter to provide drive power to each of the plurality of converters.

[0092] At least one output terminal of a plurality of battery strings has its voltage applied to the primary-side circuit, and at this time, each of the output terminals of the plurality of battery strings in the primary-side circuit can be connected in parallel by a switching element. Here, the switching element can be, for example,... Figure 18 The diodes are shown. All output terminals of multiple battery strings are connected via diodes, allowing the highest voltage among the battery string voltages to be selectively applied. That is, even if some battery strings lack sunlight, the drive power for all converters can be provided by using the voltage of other battery strings that generate sufficient power. Redundancy is also ensured in this way. Alternatively, it is naturally possible to receive and use the voltage of a specific battery string to provide auxiliary power without diodes.

[0093] An isolation converter can include at least one of a flyback converter, a forward converter, and an LLC converter. The isolation converter can perform primary-side regulation (PSR). PSR can be performed with reference to the output voltage of a secondary circuit unit having the same reference potential as the primary circuit unit. The output of the secondary circuit unit can be controlled by referencing a voltage reflected to the primary side through a transformer. The isolation converter can use a third winding to control the output of the secondary circuit unit. The isolation converter can be controlled by referencing only the output voltage of a secondary circuit unit with the same potential as the primary circuit unit. For example, when the primary circuit unit is grounded, control can be performed by referencing the output voltage of a ground-based secondary circuit unit.

[0094] Auxiliary power can be generated by combining a separate converter with a linear regulator that takes the output of the secondary circuit as its input.

[0095] like Figure 19 As shown, the secondary-side circuitry may include: a first-stage circuitry for providing auxiliary power to the upper switch included in each converter; and a second-stage circuitry for providing auxiliary power to the lower switch included in each converter. The converter may include a high-side FET and a low-side FET, and may provide auxiliary power to each of the high-side FET and the low-side FET.

[0096] It includes a control unit for monitoring at least one of the input and output signals of a plurality of converters and the current flowing in the inductors included in each converter, transmitting the monitored information to an external source via power line communication (PLC), and generating and applying control signals for each of the plurality of converters. The secondary-side circuitry may include a tertiary-side circuitry that provides drive power to the control unit. In addition to the secondary circuitry units corresponding to each converter, secondary-level circuitry units may be additionally used for separate purposes. Furthermore, auxiliary power can be provided to various modules that require power (e.g., drive power).

[0097] After being driven by receiving auxiliary power, multiple converters 110 can receive control signals from the control unit to perform maximum power point tracking control.

[0098] like Figure 17 As shown, the solar module according to the third embodiment of the present invention includes a plurality of battery strings 130, a plurality of converters 110 and an auxiliary power supply unit 150. Figure 17 The detailed description of the solar module corresponds to the detailed description of the power conversion device according to the third embodiment, therefore overlapping descriptions will be omitted.

[0099] Each of the plurality of battery strings 130 includes one or more solar cells, and a plurality of converters 110 are connected to each battery string to form a multi-stage structure. An auxiliary power supply unit 150 provides drive power to each of the plurality of converters 110, wherein the auxiliary power supply unit 150 includes: a primary-side circuit for receiving a voltage from at least one output terminal of the plurality of battery strings; an isolation converter for outputting a voltage to a secondary circuit according to the voltage of the circuit; and a plurality of secondary circuits for providing drive power to each of the plurality of converters using the voltage output from the isolation converter.

[0100] In the primary-side circuit, the output terminals of multiple battery strings can be connected in parallel via diodes. The secondary circuit includes a primary circuit for providing auxiliary power to the upper switch included in each converter, and a secondary circuit for providing auxiliary power to the lower switch included in each converter.

[0101] It may include a control unit for monitoring at least one of an input signal, an output signal, and the current flowing in an inductor included in each converter, and for transmitting the monitored information to an external source via power line communication (PLC), or for generating and applying control signals for each of the plurality of converters, wherein the secondary side circuitry may include a tertiary side circuitry that provides drive power to the control unit.

[0102] The power conversion device according to the fourth embodiment of the present invention includes a plurality of converters 110 and an auxiliary power supply unit 150, and may further include a voltage detection unit or a control unit. In the detailed description of the power conversion device according to the fourth embodiment of the present invention, descriptions corresponding to the detailed descriptions of the first to third embodiments will be omitted. The fourth embodiment of the present invention focuses on describing the configuration of the auxiliary power supply unit for generating auxiliary power to drive the converters, etc.; therefore, even if descriptions of some configurations are omitted, the configurations according to the embodiments of the present invention can naturally be included.

[0103] A power conversion device according to a fourth embodiment of the present invention includes: a plurality of converters 110, wherein each converter is connected to a plurality of battery strings to configure multiple stages; and a plurality of auxiliary power supply units 150 for providing drive power to each of the plurality of converters using the voltage output from each battery string.

[0104] According to the configuration of the auxiliary power unit of the power conversion device according to the third embodiment, multiple auxiliary power supplies can be generated using a single isolated converter, which is advantageous in terms of reducing material costs. However, it is difficult to control the output voltage of a single secondary circuit unit, and since there is a possibility that the entire auxiliary power circuit may fail due to a failure of a part of the auxiliary power circuit, the power conversion device according to the fourth embodiment generates and provides auxiliary power to each converter individually.

[0105] In order to generate and provide auxiliary power independently, the auxiliary power supply unit 150 may include a single voltage regulator and at least one of two or more voltage regulators cascaded together.

[0106] Each auxiliary power supply unit 150, used to provide auxiliary power to each converter, may include a single voltage regulator. The single voltage regulator may include at least one of a linear regulator, a charge pump, a boost / buck converter, and a boost converter. The single voltage regulator may optionally use a linear regulator, a charge pump, a boost / buck converter, and a boost converter. If as... Figure 20 The auxiliary power unit shown is implemented as a single voltage regulator, which has the advantage of simple circuit configuration.

[0107] Because the battery string voltage varies frequently depending on the conditions of the solar cells, it is necessary to determine the range of string voltage variation and the target voltage V of the auxiliary power supply. AUX The relationship between the voltage applied to the battery string is used to apply the appropriate voltage. For example... Figure 21 As shown, when the target voltage V of the auxiliary power supply AUX When the voltage drops below the minimum battery string voltage, a step-down converter is required; therefore, a linear regulator or a step-down converter can be used in this situation. When the target voltage V of the auxiliary power supply... AUX When the voltage exceeds the maximum battery string voltage, a boost converter is required; therefore, a charge pump or boost converter can be used in this case. When only boost / buck or step-up is needed, the circuit configuration is relatively simple and can be implemented with low material costs.

[0108] However, when the target voltage V of the auxiliary power AUX When the voltage is below the highest battery string voltage but above the lowest battery string voltage, a boost and buck converter are required. In this case, a non-inverting buck-boost converter must be used, whose output voltage is not inverted to a negative voltage. A non-inverting buck-boost converter requires four semiconductor switches, which makes the circuit relatively complex and increases material costs.

[0109] The auxiliary power supply unit 150 may be a multi-output isolated converter, and in this case, the multi-output isolated converter may include: a first output for providing auxiliary power to the upper switch included in each converter, and a second output for providing auxiliary power to the lower switch included in each converter. Figure 22 As shown, a multi-output isolated converter can be used as a single regulator. By using a multi-output isolated converter, FET drive power can be supplied separately to the low-side FET (which acts as the lower switch) and the high-side FET (which acts as the upper switch) included in the converter. When supplying a single auxiliary power to the converter, the high-side FET drive power must be provided via a bootstrap circuit. Since the bootstrap circuit needs to intermittently turn on the low-side FET to charge the capacitor to maintain the output voltage, the high-side FET cannot be continuously turned on. Typically, during MLPE operation, continuous turning of the high-side FET occurs frequently to bypass the battery string voltage to the output voltage. When using an isolated converter to supply drive power to the low-side FET and the high-side FET separately, the high-side FET can be operated without a bootstrap circuit. This overcomes the disadvantages of the bootstrap circuit and allows for continuous turning of the high-side FET.

[0110] When configuring the auxiliary power supply unit, two or more voltage regulators can be cascaded. Two or more stages of voltage regulators can include at least two of linear regulators, charge pumps, boost / buck converters, and boost converters. The two stages of the voltage regulator can be of the same type or different types.

[0111] In implementing an auxiliary power supply circuit capable of boosting / buckling voltage, boost regulators and buck regulators can be cascaded. In this case, the circuit can be implemented regardless of the order in which the boost and buck regulators are arranged. In a two-stage regulator configuration, boost and buck types mean that the auxiliary power supply voltage V... AUX It can boost and buck voltages compared to the battery string voltage.

[0112] At this time, as Figure 23 As shown, a two- or more-stage voltage regulator may include a buck regulator and a boost regulator. Here, a buck regulator may include at least one of a linear regulator and a buck converter, and a boost regulator may include at least one of a charge pump and a boost converter.

[0113] As a two-stage voltage regulator, a linear regulator, charge pump, boost converter, boost / buck converter, and combination of boost converters can be used. Furthermore, when using a two-stage regulation device to achieve boost / buck functionality, a buck regulator and a boost regulator can be combined. For example... Figure 24As shown, the auxiliary power unit can be formed by a combination of a linear regulator charge pump, a linear regulator boost converter, a buck converter charge pump, and a buck converter boost converter. Combinations of 1 to 3 of these can reduce material costs compared to non-inverting buck-boost converters.

[0114] The power conversion device according to the fourth embodiment may include a control unit for monitoring at least one of an input signal, an output signal, and a current flowing in an inductor included in each converter, and for transmitting the monitored information to an external source via power line communication (PLC), or for generating and applying control signals for each of a plurality of converters, wherein the plurality of converters may receive control signals and perform maximum power point tracking control.

[0115] The solar module according to the fourth embodiment of the present invention comprises a plurality of battery strings 130, a plurality of converters 110, and an auxiliary power supply unit 150. The detailed description of the solar module according to the fourth embodiment of the present invention corresponds to the detailed description of the power conversion device according to the fourth embodiment; therefore, overlapping descriptions will be omitted.

[0116] Each of the plurality of battery strings 130 includes one or more solar cells, and a plurality of converters 110 are connected to each battery string to form a multi-stage structure. An auxiliary power supply unit 150 provides drive power to each of the plurality of converters 110 and provides drive power to each of the plurality of converters using the voltage output from each battery string. The auxiliary power supply unit may include a single voltage regulator and at least one of two or more voltage regulators cascaded together.

[0117] Those skilled in the art will understand that this embodiment can be implemented in modified forms without departing from the basic characteristics described above. Therefore, the disclosed methods should be considered in an illustrative rather than restrictive sense. The scope of the invention is shown in the claims rather than in the foregoing description, and all differences within the equivalent scope are to be interpreted as included in the invention.

Claims

1. A power conversion device, comprising: Multiple converters, each of which is connected to a multiple battery string; Multiple auxiliary power supply units are configured to provide drive power to each of the multiple converters; as well as The control unit is configured to apply a control signal to each of the plurality of converters. The multiple converters constitute a multi-stage system. Each of the plurality of auxiliary power supply units includes a cascaded two-stage voltage regulator. The two-stage voltage regulator includes a buck regulator and a boost regulator. When the preset target voltage of the auxiliary power supply unit is lower than the lowest voltage among the plurality of battery strings, the buck regulator operates, and The boost regulator operates when the preset target voltage of the auxiliary power supply unit is higher than the highest voltage among the plurality of battery strings.

2. The power conversion equipment according to claim 1, in, The plurality of converters receive the control signal and perform maximum power point tracking control.

3. The power conversion equipment according to claim 1, The plurality of converters are cascaded.

4. The power conversion equipment according to claim 1, in, The control unit monitors at least one of the following: the input signals of the plurality of converters; the output signals of the plurality of converters; and the current flowing in the inductor included in each converter.

5. The power conversion equipment according to claim 4, in, The control unit transmits the monitored information to the outside via power line communication (PLC).

6. The power conversion equipment according to claim 4, in, The control unit includes: A first control unit, configured to apply a control signal to cause the plurality of converters to perform maximum power point tracking control; and The second control unit is configured to monitor at least one of the currents flowing in the inductors included in each converter and to send the monitored information to the outside.

7. The power conversion equipment according to claim 1, in, The control unit generates a control signal individually for each converter among the plurality of converters corresponding to each battery string, based on the output signal of each of the plurality of battery strings.

8. The power conversion equipment according to claim 1, in, Control signals for the multiple converters are applied synchronously.

9. The power conversion equipment according to claim 1, in, Control signals are applied to the plurality of converters with a predetermined phase difference.

10. The power conversion device according to claim 9, in, The phase difference varies depending on the number of converters that make up the multi-stage.

11. The power conversion equipment according to claim 1, in, The control signals include PWM signals for the switching devices included in the converter.

12. The power conversion equipment according to claim 1, in, Each of the plurality of battery strings includes at least one or more batteries.

13. A solar module, comprising: Multiple battery strings, each of the multiple battery strings comprising one or more solar cells; Multiple converters, each of which is connected to each of the battery strings; Multiple auxiliary power supply units are configured to provide drive power to each of the multiple converters; as well as A control unit is configured to monitor information about each of the plurality of converters and to apply control signals to each of the plurality of converters based on the monitored information. The multiple converters constitute a multi-stage system. Each of the plurality of auxiliary power supply units includes a cascaded two-stage voltage regulator. The two-stage voltage regulator includes a buck regulator and a boost regulator. When the preset target voltage of the auxiliary power supply unit is lower than the lowest voltage among the plurality of battery strings, the buck regulator operates, and The boost regulator operates when the preset target voltage of the auxiliary power supply unit is higher than the highest voltage among the plurality of battery strings.

14. The solar module according to claim 13, in, The multiple converters are cascaded together.

15. The solar module according to claim 13, in, The control unit monitors at least one of the following: the input signals of the plurality of converters; the output signals of the plurality of converters; and the current flowing in the inductor included in each converter.

16. The solar module according to claim 15, in, The control unit transmits the monitored information to the outside via power line communication (PLC).

17. The solar module according to claim 15, in, The control unit includes: A first control unit, configured to apply a control signal to cause the plurality of converters to perform maximum power point tracking control; and A second control unit is configured to monitor at least one of the currents flowing in the inductors included in each converter and to send the monitored information to an external source.

18. The solar module according to claim 13, in, The control unit generates a control signal individually for each converter among the plurality of converters corresponding to each battery string, based on the output signal of each of the plurality of battery strings.

19. The solar module according to claim 13, in, Control signals for the plurality of converters are applied synchronously or with a predetermined phase difference.

20. The solar module according to claim 19, in, The phase difference varies depending on the number of converters that make up the multi-stage.

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