Direct current conversion circuit, power conversion device, and photovoltaic power generation system

Abstract

The application provides a direct current conversion circuit, a power conversion device and a photovoltaic power generation system. The direct current conversion circuit comprises: a switching module, the switching module being connected with a power generation direct current power supply and an energy storage direct current power supply, and the switching module being configured to control access to the power generation direct current power supply or the energy storage direct current power supply; a direct current conversion module, a first end of the direct current conversion module being connected with the switching module, and a second end of the direct current conversion module being connected with an alternating current-direct current conversion circuit; wherein when the switching module turns on a path between the first end of the direct current conversion module and the energy storage direct current power supply, the direct current conversion module converts a direct current voltage input by the energy storage direct current power supply, or the direct current conversion module converts a direct current voltage input by the alternating current-direct current conversion circuit. The direct current conversion circuit can make the photovoltaic panel and the energy storage direct current power supply share the same direct current converter, thereby being beneficial to reducing the power loop area of the photovoltaic power generation system.

Description

Technical Field

[0001] This application relates to the field of energy technology, specifically to a DC-DC converter circuit, a power conversion device, and a photovoltaic power generation system. Background Technology

[0002] Currently, photovoltaic (PV) and energy storage systems typically include a photovoltaic power source, an energy storage battery, an inverter, a first DC-DC converter that converts the DC voltage output from the PV panel, and a second DC-DC converter that converts the DC voltage output from the PV panel. These first and second DC-DC converters enable the PV panel to generate electricity, the energy storage battery to generate electricity, and the PV system to store energy. However, because separate first and second DC-DC converters are required, the power circuit of the PV power generation system occupies an excessively large area on the solar panels. Utility Model Content

[0003] This application provides a DC-DC converter circuit, a power conversion device, and a photovoltaic power generation system, aiming to solve the above-mentioned technical problems.

[0004] In a first aspect, this application provides a DC-DC converter circuit. The input terminal of the DC-DC converter circuit is used to connect to a DC power source for power generation and a DC power source for energy storage. The output terminal of the DC-DC converter circuit is used to connect to an AC-DC conversion circuit. The DC-DC converter circuit includes:

[0005] The switching module has its first terminal electrically connected to both the generating DC power supply and the energy storage DC power supply. The switching module is configured to control the generation DC power supply or the energy storage DC power supply to be connected to the second terminal of the switching module.

[0006] The DC-DC converter module has its first terminal electrically connected to the second terminal of the switching module, and its second terminal is connected to the AC-DC conversion circuit.

[0007] Specifically, when the switching module connects the first terminal of the DC-DC converter module to the energy storage DC power supply, the DC-DC converter module is used to convert the DC voltage input to the energy storage DC power supply, or the DC-DC converter module is used to convert the DC voltage input to the AC-DC conversion circuit.

[0008] In some embodiments, when the switching module connects the first terminal of the DC-DC converter module to the DC power supply, the DC-DC converter module is used to convert the DC voltage input to the DC power supply.

[0009] In some embodiments, the second terminal of the switching module is also connected to the second terminal of the DC-DC converter module;

[0010] When the switching module connects the second terminal of the DC-DC converter module to the DC power supply and the first terminal of the DC-DC converter module to the DC power supply, the DC-DC converter module is used to convert the DC voltage output by the DC power supply to the charging voltage of the DC power supply.

[0011] In some embodiments, the switch module includes a first switch and a second switch;

[0012] The first terminal of the first switch is connected to the DC power supply for generation, and the second terminal of the first switch is connected to the first terminal of the DC-DC converter module.

[0013] The first terminal of the second switch is connected to the energy storage DC power supply, and the second terminal of the first switch is connected to the first terminal of the DC-DC converter module.

[0014] In some embodiments, the switch module further includes a third switch;

[0015] The first terminal of the third switch is connected to the DC power supply for generation, and the second terminal of the third switch is connected to the second terminal of the DC-DC converter module.

[0016] In some embodiments, during the operation of the DC-DC converter circuit, at least one and at most two of the first switch, the second switch, and the third switch are closed.

[0017] In some embodiments, the first switch includes a first transistor and a second transistor;

[0018] The first terminal of the first transistor is connected to the DC power supply for power generation, the second terminal of the first transistor is connected to the second terminal of the second transistor, and the first terminal of the second transistor is connected to the first terminal of the DC-DC converter module.

[0019] In some embodiments, the second switch includes a third transistor and a fourth transistor;

[0020] The first terminal of the third transistor is connected to the energy storage DC power supply, the second terminal of the third transistor is connected to the second terminal of the fourth transistor, and the first terminal of the fourth transistor is connected to the first terminal of the DC-DC converter module.

[0021] In some embodiments, the third switch includes a fifth transistor and a sixth transistor;

[0022] The first terminal of the fifth transistor is connected to the DC power supply for power generation, the second terminal of the fifth transistor is connected to the second terminal of the sixth transistor, and the first terminal of the sixth transistor is connected to the second terminal of the DC-DC converter module.

[0023] Secondly, this application provides a power conversion device, comprising:

[0024] The DC-DC converter circuit as described in the first aspect;

[0025] An AC / DC conversion circuit is provided, wherein the output terminal of the AC / DC conversion circuit is electrically connected to the DC conversion circuit.

[0026] Thirdly, this application provides a photovoltaic power generation system, comprising:

[0027] The DC-DC converter circuit as described in the first aspect;

[0028] Photovoltaic panel, connected to the switching module of DC-DC converter circuit;

[0029] Energy storage battery, which is connected to the switching module of the DC-DC converter circuit;

[0030] Inverter, which is connected to the DC-DC converter circuit.

[0031] In this application, the DC-DC converter circuit, under the control of the switching module, can realize the power generation and charging / energy storage process of the energy storage DC power supply. Taking the application of the DC-DC converter circuit of this application in the field of photovoltaic power generation as an example, combined with... Figure 1 as well as Figure 2 It can be seen that the DC-DC converter circuit of this application allows the photovoltaic panel and the energy storage DC power supply to share the same DC-DC converter, which is beneficial to reducing the area occupied by the power circuit of the photovoltaic power generation system. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 A schematic diagram of a photovoltaic power generation system in related technologies is shown;

[0034] Figure 2 A schematic diagram of a DC-DC converter circuit in an embodiment of this application is shown;

[0035] Figure 3 A schematic diagram of a DC-DC converter circuit in an embodiment of this application is shown;

[0036] Figure 4 Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0037] Figure 5 Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0038] Figure 6Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0039] Figure 7 Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0040] Figure 8 Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0041] Figure 9 Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0042] Figure 10 Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0043] Figure 11 Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0044] Figure 12 Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0045] Figure 13 Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0046] Figure 14 Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0047] Figure 15 Another schematic diagram of the DC-DC converter circuit in an embodiment of this application is shown;

[0048] Figure 16 A schematic diagram of a photovoltaic power generation system according to an embodiment of this application is shown.

[0049] Among them, there are 100 DC-DC converter circuits, 10 switching modules, 20 DC-DC converter modules, 200 DC power generation power supplies, 300 DC power storage power supplies, and 400 AC-DC conversion circuits.

[0050] First switch S1, second switch S2, third switch S3, first transistor M1, second transistor M2, third transistor M4, fourth transistor M4, first capacitor C1, second capacitor C2, first switching transistor M01, second switching transistor M02, third switching transistor M03, fourth switching transistor M04. Detailed Implementation

[0051] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0052] In the description of this utility model, the term "exemplary" is used to mean "serving as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to implement and use this utility model. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this utility model can be implemented without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid obscuring the description of this utility model with unnecessary detail. Therefore, this utility model is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0053] Currently, see Figure 1 , Figure 1 A schematic diagram of a photovoltaic power generation system in related technologies is shown. The photovoltaic power generation system typically includes a DC bus capacitor C01, a DC bus capacitor C02, a photovoltaic panel, an energy storage battery, an inverter, a first DC converter, and a second DC converter. The photovoltaic power generation system has at least four operating modes: photovoltaic power generation, energy storage power generation, photovoltaic energy storage, and reverse charging.

[0054] Specifically, when the photovoltaic power generation system is in photovoltaic power generation mode, the second DC converter stops working, and the DC voltage output by the photovoltaic panel is converted into a DC voltage that meets the input requirements of the inverter by the first DC converter. Then, the inverter converts the DC voltage into AC voltage, thereby supplying power to AC loads or connecting to the grid through AC voltage.

[0055] When the photovoltaic power generation system is in energy storage power generation mode, the first DC converter stops working, and the DC voltage output by the energy storage battery is converted into a DC voltage that meets the input requirements of the inverter by the second DC converter. Then, the inverter converts the DC voltage into AC voltage, thereby supplying power to AC loads or connecting to the grid through AC voltage.

[0056] When the photovoltaic power generation system is in photovoltaic energy storage mode, the inverter stops working. The DC voltage output by the photovoltaic panel is converted into a DC voltage suitable for charging the energy storage battery by the first DC converter and / or the second DC converter, so that the electrical energy output by the photovoltaic panel from solar energy can be stored in the energy storage battery when it is not necessary to supply power to the load or connect to the grid.

[0057] When the photovoltaic power generation system is in reverse charging mode, the first DC converter stops working, the inverter converts the AC voltage output from the grid into DC voltage and inputs it into the second DC converter. The second DC converter outputs a DC voltage that is compatible with the charging of the energy storage battery, thereby storing the excess electrical energy of the grid in the energy storage battery to achieve the grid load regulation function of "peak shaving and valley filling".

[0058] However, achieving the above four operating conditions requires a first DC-DC converter and a second DC-DC converter, which leads to an excessively large power loop circuit area in the photovoltaic power generation system. Therefore, this application provides a DC-DC conversion circuit and a photovoltaic power generation system, which will be described in detail below.

[0059] First, refer to Figure 2 , Figure 2 A schematic diagram of a DC-DC converter circuit 100 in an embodiment of this application is shown. The input terminal of the DC-DC converter circuit 100 is used to connect to a DC power source 200 and a DC power source 300, and the output terminal of the DC-DC converter circuit 100 is used to connect to an AC-DC converter circuit 400. The DC-DC converter circuit 100 includes a switching module 10 and a DC-DC converter module 20.

[0060] Specifically, the DC power supply 200 refers to a device that can convert other forms of energy into DC power. For example, taking solar power generation as an example, the DC power supply 200 can include photovoltaic panels. Photovoltaic panels can be, but are not limited to, silicon-based photovoltaic panels, thin-film photovoltaic panels, or organic photovoltaic panels. Silicon-based photovoltaic panels include monocrystalline silicon photovoltaic panels and polycrystalline silicon photovoltaic panels, while thin-film photovoltaic panels include copper indium gallium selenide (CIGS) photovoltaic panels and perovskite photovoltaic panels. As another example, taking wind power generation, thermal power generation, and hydropower generation as examples, the DC power supply 200 can include a DC generator that outputs DC voltage.

[0061] The energy storage DC power supply 300 refers to a device that can perform DC voltage charging and DC voltage discharging. For example, the energy storage DC power supply 300 may include an energy storage battery, which may be, but is not limited to, lead-acid batteries, lithium-ion batteries, sodium-sulfur batteries, nickel-metal hydride batteries, nickel-cadmium batteries, etc.

[0062] The AC / DC converter circuit 400 can convert the DC voltage output from the DC converter circuit 100 into AC voltage, thereby supplying power to an AC load or connecting the AC power to the power grid PG; alternatively, the AC / DC converter circuit 400 can also convert the AC voltage of the power grid PG into DC voltage and input it into the DC converter circuit 100. Generally, the AC / DC converter circuit 400 includes multiple switching transistors (such as thyristors, IGBTs, etc.), and adjusts the output voltage waveform by controlling the on and off states of the switching transistors, thereby realizing the conversion of DC to AC or DC to AC.

[0063] For example, the AC / DC conversion circuit 400 may include, but is not limited to, a half-bridge inverter circuit, a full-bridge inverter circuit, or a push-pull inverter circuit.

[0064] The first terminal of the switching module 10 of the DC-DC converter circuit 100 is electrically connected to the DC power supply 200 and the DC power supply 300, respectively. The switching module 10 is configured to control the DC power supply 200 or the DC power supply 300 to be connected to the second terminal of the switching module 10. For example, the switching module 10 can control the connection of the DC power supply 200, so that the path between the first terminal of the DC-DC converter 20 and the DC power supply 200 is connected; or, for example, the switching module 10 can control the connection of the DC power supply 300, so that the path between the first terminal of the DC-DC converter 20 and the DC power supply 300 is connected.

[0065] For example, the switching module 10 may include, but is not limited to, mechanical switches such as relays and circuit breakers, or switching transistors with switching functions such as MOSFETs, transistors, IGBTs, or JEFTs.

[0066] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.

[0067] The first terminal of the DC-DC converter module 20 is electrically connected to the second terminal of the switch module 10, and the second terminal of the DC-DC converter module 20 is connected to the AC-DC conversion circuit 400. The DC-DC converter module 20 is configured to convert DC voltage. For example, when the switch module 10 controls the first terminal of the DC-DC converter module 20 to connect to the generator DC power supply 200, the DC-DC converter module 20 can convert the DC voltage output by the generator DC power supply 200 into a DC voltage that meets the input requirements of the AC-DC conversion circuit 400, so that the AC-DC conversion circuit 400 converts the DC voltage provided by the second terminal of the DC-DC converter module 20 into AC voltage. As another example, when the switch module 10 controls the first terminal of the DC-DC converter module 20 to connect to the energy storage DC power supply 300, the DC-DC converter module 20 can convert the DC voltage output by the AC-DC conversion circuit 400 into a DC voltage that meets the charging requirements of the energy storage DC power supply 300, so that the energy storage DC power supply 300 can be charged.

[0068] For example, the DC-DC converter module 20 may include, but is not limited to, DC-DC converter circuits such as BOOST boost circuit, BUCK buck circuit, BOOST-BUCK buck-boost circuit, and Cuk circuit.

[0069] In this embodiment, when the switch module 10 connects the first terminal of the DC-DC converter module 20 to the energy storage DC power supply 300, the DC-DC converter module 20 can convert the DC voltage input to the energy storage DC power supply 300, or the DC-DC converter module 20 can convert the DC voltage input to the AC-DC converter circuit 400; while when the switch module 10 connects the first terminal of the DC-DC converter module 20 to the power generation DC power supply 200, the DC-DC converter module 20 converts the DC voltage input to the power generation DC power supply 200.

[0070] For example, see Figure 3 , Figure 3 The diagram illustrates a working schematic of the DC-DC converter circuit 100 in an embodiment of this application. After the switching module 10 turns on the path between the first terminal of the DC-DC converter module 20 and the energy storage DC power supply 300, the DC voltage of the energy storage DC power supply 300 is output to the first terminal of the DC-DC converter module 20. The DC-DC converter module 20 can convert the DC voltage input to the energy storage DC power supply 300 and output a DC voltage that meets the input requirements of the AC-DC converter circuit 400 at the second terminal, so that the AC-DC converter circuit 400 outputs an AC voltage. Finally, the AC voltage output by the AC-DC converter circuit 400 is used to supply power to the AC load or to be connected to the power grid PG.

[0071] For example, see Figure 4 , Figure 4This illustration shows another working diagram of the DC-DC converter circuit 100 in an embodiment of this application. After the switching module 10 turns on the path between the first terminal of the DC-DC converter module 20 and the energy storage DC power supply 300, the AC-DC converter circuit 400 converts the AC voltage of the power grid PG into DC voltage. The AC-DC converter circuit 400 provides DC voltage to the second terminal of the DC-DC converter module 20. The DC-DC converter module 20 can convert the DC voltage input to the AC-DC converter circuit 400 and output a DC voltage that meets the charging requirements of the energy storage DC power supply 300 at the first terminal. Finally, the DC voltage output by the DC-DC converter module 20 is used to charge the energy storage DC power supply 300.

[0072] For example, see Figure 5 , Figure 5 This illustration shows another working diagram of the DC-DC converter circuit 100 in an embodiment of this application. After the switching module 10 turns on the path between the first terminal of the DC-DC converter module 20 and the DC power supply 200, the DC voltage of the DC power supply 200 is output to the first terminal of the DC-DC converter module 20. The DC-DC converter module 20 can convert the DC voltage input to the DC power supply 200 and output a DC voltage that meets the input requirements of the AC-DC converter circuit 400 at the second terminal. This allows the AC-DC converter circuit 400 to convert the DC voltage provided by the second terminal of the DC-DC converter module 20 into an AC voltage. Finally, the AC voltage output by the AC-DC converter circuit 400 is used to power AC loads or connect to the power grid PG.

[0073] It can be seen that the DC-DC converter circuit 100, under the control of the switching module 10, utilizes the same DC-DC converter to realize the power generation and charging energy storage process of the energy storage DC power supply 300, and can also realize the power generation process of the power generation DC power supply 200. Taking the DC-DC converter circuit 100 of this application as an example in the field of photovoltaic power generation, combined with... Figure 1 as well as Figure 2 It can be seen that the DC-DC converter circuit 100 of this application allows the photovoltaic panel and the energy storage DC power supply 300 to share the same DC-DC converter, which is beneficial to reducing the area occupied by the power circuit of the photovoltaic power generation system.

[0074] In some embodiments of this application, the second terminal of the switch module 10 is also connected to the second terminal of the DC-DC converter module 20. When the switch module 10 conducts the path between the second terminal of the DC-DC converter module 20 and the DC power supply 200, and conducts the path between the first terminal of the DC-DC converter module 20 and the DC power supply 300, the DC-DC converter module 20 converts the DC voltage output by the DC power supply 200 into the charging voltage of the DC power supply 300.

[0075] For example, see Figure 6 , Figure 6This illustration shows another working diagram of the DC-DC converter circuit 100 in an embodiment of this application. When the switching module 10 connects the second terminal of the DC-DC converter module 20 to the DC power generation power supply 200 and connects the first terminal of the DC-DC converter module 20 to the DC power storage power supply 300, the AC-DC converter circuit 400 stops working. At this time, the DC-DC converter module 20 converts the DC voltage provided by the DC power generation power supply 200 and outputs a DC voltage at the first terminal that meets the charging requirements of the DC power storage power supply 300, so that the DC power storage power supply 300 can charge and store energy.

[0076] As can be seen, after the switch module 10 is connected to the second end of the DC-DC converter module 20, the switch module 10 can enable the energy storage DC power supply 300 to be charged based on the electrical energy provided by the power generation DC power supply 200. Taking the DC-DC converter circuit 100 applied to the photovoltaic power generation field as an example, this is equivalent to the photovoltaic power generation system performing photovoltaic energy storage, so that the electrical energy output by the photovoltaic panel can be stored in the energy storage battery when the power grid is not required.

[0077] In some embodiments of this application, see Figure 7 , Figure 7 Another schematic diagram of the DC-DC converter circuit 100 in an embodiment of this application is shown, wherein the switching module 10 includes a first switch S1 and a second switch S2; the first end of the first switch S1 is connected to the DC power supply 200, and the second end of the first switch S1 is connected to the first end of the DC-DC converter module 20; the first end of the second switch S2 is connected to the DC power supply 300, and the second end of the first switch S1 is connected to the first end of the DC-DC converter module 20.

[0078] It should be noted that when the first switch S1 is closed and the second switch S2 is open, the switch module 10 connects the first terminal of the DC-DC converter module 20 and the DC power supply 200. At this time, the DC-DC converter module 20 can convert the DC voltage input to the DC power supply 200 and output a DC voltage that meets the input requirements of the AC-DC converter circuit 400 at the second terminal. When the first switch S1 is open and the second switch S2 is closed, if the DC voltage of the energy storage DC power supply 300 is output to the first terminal of the DC-DC converter module 20, the DC-DC converter module 20 can convert the DC voltage input to the energy storage DC power supply 300 and output a DC voltage that meets the input requirements of the AC-DC converter circuit 400 at the second terminal. If the AC-DC converter circuit 400 provides DC voltage to the second terminal of the DC-DC converter module 20, the DC-DC converter module 20 can convert the DC voltage input to the AC-DC converter circuit 400 and output a DC voltage that meets the charging requirements of the energy storage DC power supply 300 at the first terminal.

[0079] In some embodiments of this application, such as an embodiment where the switching module 10 is also connected to the second terminal of the DC-DC converter module 20, see [reference]. Figure 8 , Figure 8 Another schematic diagram of the DC-DC converter circuit 100 in an embodiment of this application is shown, wherein the switching module 10 further includes a third switch S3; the first end of the third switch S3 is connected to the DC power supply 200, and the second end of the third switch S3 is connected to the second end of the DC-DC converter module 20.

[0080] It should be noted that when the first switch S1 is open, the second switch S2 is closed, and the third switch S3 is closed, the AC / DC conversion circuit 400 stops working. At this time, the DC conversion module 20 converts the DC voltage provided by the generator DC power supply 200 and outputs a DC voltage at the first terminal that meets the charging requirements of the energy storage DC power supply 300, so that the energy storage DC power supply 300 can charge and store energy.

[0081] In some embodiments of this application, see Figure 9 , Figure 9 This illustration shows another schematic diagram of the DC-DC converter circuit 100 in an embodiment of this application. The DC-DC converter module 20 includes a first capacitor C1, a second capacitor C2, an inductor L0, a first switching transistor M01, and a second switching transistor M02. These components form a DC-DC converter. When a DC voltage is input to the first terminal of the DC-DC converter module 20, the DC-DC converter acts as a BOOST boost circuit, outputting a boosted DC voltage. When a DC voltage is input to the second terminal of the DC-DC converter module 20, the DC-DC converter acts as a BUCK buck circuit, outputting a bucked DC voltage to charge the energy storage DC power supply 300.

[0082] In some embodiments of this application, during the operation of the DC-DC converter circuit 100, at least one and at most two of the first switch S1, the second switch S2, and the third switch S3 are closed.

[0083] For example, see Figure 9 In this configuration, only the first switch S1 is closed among the first switch S1, the second switch S2, and the third switch S3, thereby enabling the DC-DC converter module 20 to convert the DC voltage provided by the generator DC power supply 200.

[0084] For example, see Figure 10 , Figure 10 The diagram shows another working schematic of the DC-DC converter circuit 100 in an embodiment of this application, wherein only the second switch S2 is closed among the first switch S1, the second switch S2 and the third switch S3, so that the DC-DC converter module 20 can convert the DC voltage provided by the energy storage DC power supply 300, or the DC-DC converter module 20 can output DC voltage to charge the energy storage DC power supply 300.

[0085] For example, see Figure 11 , Figure 11 Another schematic diagram of the operation of the DC-DC converter circuit 100 in this embodiment is shown, wherein only the second switch S2 and the third switch S3 are closed, thereby enabling the DC-DC converter module 20 to convert the DC voltage provided by the AC-DC converter circuit 400, and ultimately enabling the energy storage DC power supply 300 to charge and store energy.

[0086] It should be noted that in some possible embodiments, if the DC voltage output by the DC power supply 200 meets the input requirements of the AC-DC conversion circuit 400, then only the third switch S3 among the first switch S1, the second switch S2 and the third switch S3 can be closed, so that the AC-DC conversion circuit 400 can directly convert the DC voltage output by the DC power supply 200 into AC voltage.

[0087] In some embodiments of this application, see further reference. Figure 12 , Figure 12 Another schematic diagram of the DC-DC converter circuit 100 in an embodiment of this application is shown, wherein the first switch S1 includes a first transistor M1 and a second transistor M2; the first terminal of the first transistor M1 is connected to the DC power supply 200, the second terminal of the first transistor M1 is connected to the second terminal of the second transistor M2, and the first terminal of the second transistor M2 is connected to the first terminal of the DC-DC converter module 20.

[0088] It should be noted that in the embodiments of this application, the first terminal of each transistor is one of the source and the drain, and the second terminal of each transistor is the other of the source and the drain. Since the source and drain of a transistor can be structurally symmetrical, they can be structurally indistinguishable. That is, the first and second terminals of the transistors in the embodiments of this application can be structurally indistinguishable. For example, when the transistor is a P-type transistor, the first terminal is the source and the second terminal is the drain; for example, when the transistor is an N-type transistor, the first terminal is the drain and the second terminal is the source.

[0089] exist Figure 9Since the second terminal of the first transistor M1 is connected to the second terminal of the second transistor M2, the body diodes of the first transistor M1 and the second transistor M2 have opposite conduction directions. When the first transistor M1 and the second transistor M2 are in the off state, the body diodes with opposite conduction directions can disconnect the path between the DC power supply 200 and the first terminal of the DC-DC converter module 20, thus avoiding the phenomenon that the path between the DC power supply 200 and the first terminal of the DC-DC converter module 20 is unidirectionally connected due to the body diode of a single transistor.

[0090] In some embodiments of this application, see further reference. Figure 12 The second switch S2 includes a third transistor M4 and a fourth transistor M4; the first terminal of the third transistor M4 is connected to the energy storage DC power supply 300, the second terminal of the third transistor M4 is connected to the second terminal of the fourth transistor M4, and the first terminal of the fourth transistor M4 is connected to the first terminal of the DC-DC converter module 20.

[0091] Similarly, since the second terminal of the third transistor M4 is connected to the second terminal of the fourth transistor M4, the body diodes of the third transistor M4 and the fourth transistor M4 have opposite conduction directions. When the third transistor M4 and the fourth transistor M4 are in the off state, the body diodes with opposite conduction directions can disconnect the path between the energy storage DC power supply 300 and the first terminal of the DC-DC converter module 20, thus avoiding the phenomenon that the path between the energy storage DC power supply 300 and the first terminal of the DC-DC converter module 20 is unidirectionally connected due to the body diode of a single transistor.

[0092] In some embodiments of this application, see further reference. Figure 12 The third switch S3 includes a fifth transistor and a sixth transistor; the first terminal of the fifth transistor is connected to the DC power supply 200, the second terminal of the fifth transistor is connected to the second terminal of the sixth transistor, and the first terminal of the sixth transistor is connected to the second terminal of the DC-DC converter module 20.

[0093] Similarly, since the second terminal of the fifth transistor is connected to the second terminal of the sixth transistor, the body diodes of the fifth transistor and the sixth transistor have opposite conduction directions. When the fifth transistor and the sixth transistor are in the off state, the body diodes with opposite conduction directions can disconnect the path between the DC power supply 200 and the second terminal of the DC converter module 20, thus avoiding the phenomenon that the path between the DC power supply 200 and the second terminal of the DC converter module 20 is unidirectionally connected due to the body diode of a single transistor.

[0094] Those skilled in the art will understand that the above embodiments only show the switching configuration of the switching module 10 when there is only one generating DC power supply 200 and one energy storage DC power supply 300. When the number of generating DC power supplies 200 and / or energy storage DC power supplies 300 changes, the number of switches in the switching module 10 can be adaptively adjusted. For example, see [reference]. Figure 13 , Figure 13 Another schematic diagram of the DC-DC converter circuit 100 in this application embodiment is shown. When the number of parallel energy storage DC power supplies 300 increases, the switching module 10 can set the corresponding third transistor M4 and fourth transistor M4 to control the charging and discharging of the corresponding energy storage DC power supplies 300.

[0095] It is worth noting that the above description of the DC-DC converter circuit 100 is intended to clearly illustrate the implementation and verification process of this application. Those skilled in the art can also make equivalent modifications under the guidance of this application; for example, refer to... Figure 14 , Figure 14 This illustration shows another schematic diagram of the DC-DC converter circuit 100 in an embodiment of this application. The switching module 10 may further include a fourth switch S4. The fourth switch S4, in conjunction with the second switch S2, can control whether the positive and negative output terminals of the energy storage DC power supply 300 are turned on at the first terminal of the DC-DC converter module 20. For example, see [reference needed]. Figure 15 , Figure 15 Another schematic diagram of the DC-DC converter circuit 100 in an embodiment of this application is shown, wherein the DC-DC converter module 20 may include a BUCK-BOOST step-up / step-down circuit composed of a first capacitor C1, a second capacitor C2, an inductor L0, a first switching transistor M01, a second switching transistor M02, a third switching transistor M03, and a fourth switching transistor M04.

[0096] Furthermore, to better implement the DC-DC converter circuit 100 in the embodiments of this application, based on the DC-DC converter circuit 100, this application also provides a power conversion device. This power conversion device includes the DC-DC converter circuit 100 as described in any of the above embodiments and an AC-DC conversion circuit 400, with the AC-DC conversion circuit 400 electrically connected to the output terminal of the DC-DC converter circuit 100. Since the power conversion device in the embodiments of this application incorporates the DC-DC converter circuit 100 of the above embodiments, it possesses all the beneficial effects of the DC-DC converter circuit 100, which will not be elaborated further here.

[0097] Furthermore, to better implement the DC-DC converter circuit 100 in the embodiments of this application, this application also provides a photovoltaic power generation system based on the DC-DC converter circuit 100, see reference. Figure 16 , Figure 16A schematic diagram of a photovoltaic power generation system according to an embodiment of this application is shown. The photovoltaic power generation system includes a DC-DC converter circuit 100 as described in any of the above embodiments, a photovoltaic panel 500, an energy storage battery 600, and an inverter 700. The photovoltaic panel 500 is connected to the switching module 10 of the DC-DC converter circuit 100, the energy storage battery 600 is connected to the switching module 10 of the DC-DC converter circuit 100, and the inverter 700 is connected to the DC-DC converter circuit 100. Since the photovoltaic power generation system in this embodiment of the application has all the beneficial effects of the DC-DC converter circuit 100 described in the above embodiments, it will not be repeated here.

[0098] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the detailed descriptions of other embodiments above, which will not be repeated here.

[0099] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0100] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0101] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the utility model, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the present application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0102] The above provides a detailed description of a DC-DC converter circuit, a power conversion device, and a photovoltaic power generation system provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A DC-DC converter circuit, characterized in that, The input terminal of the DC-DC converter circuit is used to connect to both a DC power source for generation and a DC power source for energy storage. The output terminal of the DC-DC converter circuit is used to connect to an AC-DC conversion circuit. The DC-DC converter circuit includes: A switching module, wherein the first terminal of the switching module is electrically connected to the generating DC power supply and the energy storage DC power supply respectively, and the switching module is configured to control the generating DC power supply or the energy storage DC power supply to be connected to the second terminal of the switching module; A DC-DC converter module, wherein a first terminal of the DC-DC converter module is electrically connected to a second terminal of the switching module, and the second terminal of the DC-DC converter module is connected to the AC-DC conversion circuit; Specifically, when the switching module connects the first terminal of the DC-DC converter module to the energy storage DC power supply, the DC-DC converter module is used to convert the DC voltage input to the energy storage DC power supply, or the DC-DC converter module is used to convert the DC voltage input to the AC-DC conversion circuit.

2. The DC-DC converter circuit as described in claim 1, characterized in that, When the switching module connects the first terminal of the DC-DC converter module to the DC power supply, the DC-DC converter module is used to convert the DC voltage input by the DC power supply.

3. The DC-DC converter circuit as described in claim 1, characterized in that, The second terminal of the switching module is also connected to the second terminal of the DC-DC converter module; When the switching module connects the second terminal of the DC-DC converter module to the DC power supply and the first terminal of the DC-DC converter module to the DC power supply, the DC-DC converter module is used to convert the DC voltage output by the DC power supply into the charging voltage of the DC power supply.

4. The DC-DC converter circuit as described in claim 1, characterized in that, The switch module includes a first switch and a second switch; The first terminal of the first switch is connected to the DC power supply for power generation, and the second terminal of the first switch is connected to the first terminal of the DC-DC converter module. The first end of the second switch is connected to the energy storage DC power supply, and the second end of the first switch is connected to the first end of the DC-DC converter module.

5. The DC-DC converter circuit as described in claim 4, characterized in that, The switch module also includes a third switch; The first terminal of the third switch is connected to the DC power source, and the second terminal of the third switch is connected to the second terminal of the DC-DC converter module.

6. The DC-DC converter circuit as described in claim 5, characterized in that, During the operation of the DC-DC converter circuit, at least one and at most two of the first switch, the second switch, and the third switch are closed.

7. The DC-DC converter circuit as described in claim 4, characterized in that, The first switch includes a first transistor and a second transistor; The first terminal of the first transistor is connected to the DC power supply, the second terminal of the first transistor is connected to the second terminal of the second transistor, and the first terminal of the second transistor is connected to the first terminal of the DC-DC converter module.

8. The DC-DC converter circuit as described in claim 4, characterized in that, The second switch includes a third transistor and a fourth transistor; The first terminal of the third transistor is connected to the energy storage DC power supply, the second terminal of the third transistor is connected to the second terminal of the fourth transistor, and the first terminal of the fourth transistor is connected to the first terminal of the DC-DC converter module.

9. The DC-DC converter circuit as described in claim 5, characterized in that, The third switch includes a fifth transistor and a sixth transistor; The first terminal of the fifth transistor is connected to the DC power supply, the second terminal of the fifth transistor is connected to the second terminal of the sixth transistor, and the first terminal of the sixth transistor is connected to the second terminal of the DC-DC converter module.

10. A power conversion device, characterized in that, include: The DC-DC converter circuit as described in any one of claims 1 to 9; An AC / DC conversion circuit is provided, wherein the output terminal of the AC / DC conversion circuit is electrically connected to the DC conversion circuit.

11. A photovoltaic power generation system, characterized in that, include: The DC-DC converter circuit as described in any one of claims 1 to 9; A photovoltaic panel, wherein the photovoltaic panel is connected to the switching module of the DC-DC conversion circuit; An energy storage battery is connected to the switching module of the DC-DC converter circuit. An inverter, which is connected to the DC-DC converter circuit.

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