Control method of dc / dc conversion circuit and related device

Abstract

The application discloses a control method of a DC / DC conversion circuit and related devices, and relates to the technical field of power conversion. The DC / DC conversion circuit is characterized in that a corresponding voltage stabilizer is connected in series with a diode between positive and negative transmission branches in a BUCK circuit; when a switch tube in the BUCK circuit is turned off, the voltage across the inductor in the corresponding BUCK circuit is the difference between the input voltage of the BUCK circuit and the voltage of the voltage stabilizer, the rate of change of the inductor current can be reduced, and the ripple of the inductor current is reduced, so that the inductor can select a device with a smaller inductance; when the switch tube is turned on, the voltage across the switch tube is the difference between the output voltage of the DC / DC conversion circuit and the voltage of the voltage stabilizer, and the voltage borne by the switch tube can be reduced.

Description

Technical Field

[0001] This application relates to the field of power conversion technology, and in particular to a control method and related apparatus for a DC / DC conversion circuit. Background Technology

[0002] In a two-stage inverter system, a DC / DC converter circuit is typically placed before the subsequent DC / AC converter circuit to control the voltage of the power supply connected to the DC side of the system. As the DC-side voltage level of the system continues to increase, the voltage withstand requirements for power switching devices such as IGBTs (Insulated Gate Bipolar Transistors) or MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) in the preceding DC / DC converter circuit are also becoming increasingly stringent. Simultaneously, the ripple rate of the inductor current in the preceding DC / DC converter circuit is usually also high, requiring the selection of inductors with larger inductance values ​​or higher switching frequencies, which is detrimental to the product design of the corresponding equipment. Summary of the Invention

[0003] In view of the above problems, this application provides a control method and related apparatus for a DC / DC converter circuit to reduce the voltage across the power switching devices and the ripple rate of the inductor current in the front-end DC / DC converter circuit. The specific solution is as follows:

[0004] The first aspect of this application provides a DC / DC converter circuit, comprising: at least one BUCK circuit and at least one voltage regulator; wherein...

[0005] The input terminal of the BUCK circuit is connected to the corresponding input interface of the DC / DC converter circuit.

[0006] The output terminal of the BUCK circuit is connected to the output terminal of the DC / DC converter circuit.

[0007] In the BUCK circuit, the diodes between the positive and negative transmission branches are connected in series with the corresponding voltage regulators.

[0008] In one possible implementation, the number of both the BUCK circuit and the voltage regulator is greater than 1, and the BUCK circuit and the voltage regulator are connected in a one-to-one correspondence.

[0009] Alternatively, the number of voltage regulators is greater than 1, and at least one of the BUCK circuits is connected to at least two voltage regulators;

[0010] Alternatively, the number of BUCK circuits is greater than 1, and at least two of the BUCK circuits are connected to the same voltage regulator.

[0011] Alternatively, the number of voltage regulators is 1, the number of BUCK circuits is greater than 1, and each BUCK circuit is connected in series with the voltage regulator.

[0012] In one possible implementation, the voltage regulator includes: a voltage regulator chip; the output terminal of the voltage regulator chip is connected in series with a diode between the positive and negative transmission branches in the corresponding BUCK circuit;

[0013] Alternatively, the voltage regulator may include: a voltage regulator load; the input terminal of the voltage regulator load is connected in series with a diode between the positive and negative transmission branches in the corresponding BUCK circuit;

[0014] Alternatively, the voltage regulator may include a BOOST circuit; the input terminal of the BOOST circuit is connected in series with a diode between the positive and negative transmission branches in the BUCK circuit.

[0015] In one possible implementation, the output of the BOOST circuit is connected to the output of the DC / DC converter circuit;

[0016] Alternatively, the output of the BOOST circuit can be connected to a battery or load circuit.

[0017] In one possible implementation, the BOOST circuit is a two-level BOOST topology or a three-level BOOST topology.

[0018] In one possible implementation, the DC / DC converter circuit further includes: at least one unidirectional conducting device;

[0019] The unidirectional conducting device is connected in series with the switching transistor in the BUCK circuit;

[0020] The conduction direction of the unidirectional conducting device is the direction of the current flowing when the connected switch is controlled to conduct.

[0021] In one possible implementation, the positive input terminal of the BUCK circuit is connected to the positive input terminal of the corresponding input interface of the DC / DC converter circuit, the positive output terminal of the BUCK circuit is connected to the positive output terminal of the DC / DC converter circuit, the negative input terminal and the negative output terminal of the BUCK circuit are connected to the negative input terminal and the negative output terminal of the DC / DC converter circuit, and the voltage regulator is connected between the diode and the negative transmission branch in the positive and negative transmission branches of the BUCK circuit.

[0022] Alternatively, the negative input terminal of the BUCK circuit is connected to the negative input terminal of the corresponding input interface of the DC / DC converter circuit, the negative output terminal of the BUCK circuit is connected to the negative output terminal of the DC / DC converter circuit, the positive input terminal and the positive output terminal of the BUCK circuit are connected to the positive input terminal and the positive output terminal of the DC / DC converter circuit, and the corresponding voltage regulator is connected between the diode and the positive transmission branch in the BUCK circuit.

[0023] A second aspect of this application provides a control method for a DC / DC converter circuit, comprising:

[0024] With a preset voltage as the target, the voltage regulator is controlled to operate by the diodes connected in series between the DC / DC converter circuit and the positive and negative transmission branches in the BUCK circuit;

[0025] Control the operation of the BUCK circuit.

[0026] In one possible implementation, the objective of controlling the operation of the BUCK circuit is to make the BUCK circuit operate at the maximum power point of the power supply to which it is connected.

[0027] In one possible implementation, controlling the operation of the BUCK circuit includes:

[0028] If the input voltage of the BUCK circuit is greater than the voltage of the voltage regulator connected to the BUCK circuit, then the BUCK circuit is controlled to adjust its own input voltage.

[0029] If at least two of the BUCK circuits share the same voltage regulator and the input characteristics of each BUCK circuit meet a preset consistency condition, or if the voltage of the voltage regulator connected to the BUCK circuit is equal to the maximum power point voltage of the power supply connected to the BUCK circuit, then the switching transistor in the BUCK circuit is controlled to be normally off.

[0030] In one possible implementation, controlling the BUCK circuit to adjust its own input voltage includes:

[0031] Control the chopping action of the switching transistor in the BUCK circuit.

[0032] In one possible implementation, the operation of a voltage regulator connected in series with the diodes in the DC / DC converter circuit and the positive and negative transmission branches in the BUCK circuit is controlled with a preset voltage as the target, including:

[0033] Using the preset voltage as the voltage control target of the voltage regulator, the voltage regulator is controlled to operate so that it bears the preset portion of the input voltage of the BUCK circuit to which it is connected.

[0034] In one possible implementation, when at least two of the BUCK circuits share the same voltage regulator, the preset voltage is:

[0035] The minimum input voltage of all the BUCK circuits currently connected to the voltage regulator;

[0036] Alternatively, if the power supply connected to the BUCK circuit includes a photovoltaic module, the preset value corresponding to the current illumination conditions.

[0037] A third aspect of this application provides a controller, comprising: a processor and a memory, wherein the memory is used to store programs, instructions or code, and the processor is used to execute the programs, instructions or code in the memory to perform a control method for a DC / DC converter circuit as described in the second aspect or any implementation thereof.

[0038] A fourth aspect of this application provides a power converter, comprising: a controller and a DC / DC conversion circuit as described in the first aspect or any implementation thereof; wherein...

[0039] The DC / DC conversion circuit is controlled by the controller;

[0040] The controller is used to execute the control method for the DC / DC conversion circuit as described in the second aspect or any implementation thereof.

[0041] In one possible implementation, the power converter further includes a DC / AC conversion circuit;

[0042] The DC side of the DC / AC conversion circuit is connected to the output terminal of the DC / DC conversion circuit;

[0043] The AC side of the DC / AC conversion circuit is used to connect to the power grid and / or the load;

[0044] The DC / AC conversion circuit is controlled by the controller.

[0045] Using the above technical solution, the DC / DC converter circuit provided in this application has its BUCK circuit input terminal connected to the corresponding input interface of the DC / DC converter circuit, and its BUCK circuit output terminal connected to the output terminal of the DC / DC converter circuit. Furthermore, the diodes between the positive and negative transmission branches in the BUCK circuit are connected in series with a corresponding voltage regulator. When the switch in the BUCK circuit is turned off, the voltage across the inductor in the corresponding BUCK circuit is the difference between the input voltage of the BUCK circuit and the voltage of the voltage regulator, which can reduce the rate of change of the inductor current, thereby reducing the ripple rate of the inductor current and allowing the selection of a device with a smaller inductance value. When the switch is turned on, the voltage across it is the difference between the output voltage of the DC / DC converter circuit and the voltage of the voltage regulator, thereby reducing the voltage across the switch. Attached Figure Description

[0046] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0047] Figure 1 A schematic diagram of a DC / DC converter circuit provided in an embodiment of this application;

[0048] Figure 2 This is a schematic diagram of another structure of the DC / DC converter circuit provided in the embodiments of this application;

[0049] Figure 3 This is a schematic diagram of another structure of the DC / DC converter circuit provided in the embodiments of this application;

[0050] Figure 4 A circuit diagram of a DC / DC converter circuit provided in an embodiment of this application;

[0051] Figure 5 A schematic diagram of a current path for a DC / DC converter circuit provided in an embodiment of this application;

[0052] Figure 6 A schematic diagram of another current path for the DC / DC converter circuit provided in the embodiments of this application;

[0053] Figure 7 A schematic diagram of another current path for the DC / DC converter circuit provided in the embodiments of this application;

[0054] Figure 8 A schematic diagram of another current path for the DC / DC converter circuit provided in the embodiments of this application;

[0055] Figure 9 A schematic diagram of another current path for the DC / DC converter circuit provided in the embodiments of this application;

[0056] Figure 10 A schematic diagram of another current path for the DC / DC converter circuit provided in the embodiments of this application;

[0057] Figure 11 Another circuit diagram of the DC / DC converter circuit provided in the embodiments of this application;

[0058] Figure 12 A flowchart of a control method for a DC / DC converter circuit provided in an embodiment of this application;

[0059] Figure 13 This is a schematic diagram of the structure of a controller provided in an embodiment of this application;

[0060] Figure 14 This is a schematic diagram of a power converter provided in an embodiment of this application;

[0061] Figure 15 This is another schematic diagram of the power converter provided in the embodiments of this application;

[0062] Figure 16 A schematic diagram of a power conversion system provided in an embodiment of this application;

[0063] Figure 17 This is another schematic diagram of the power conversion system provided in the embodiments of this application. Detailed Implementation

[0064] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is for explaining specific embodiments only and is not intended to limit the scope of this application.

[0065] The embodiments of this application are described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Those skilled in the art will understand that with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0066] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0067] This application provides a DC / DC converter circuit to reduce the voltage across the power switching devices and the ripple rate of the inductor current in the preceding DC / DC converter circuit. The specific solution is as follows:

[0068] like Figure 1 As shown, the DC / DC converter circuit 10 includes: at least one ( Figure 1 (Taking one as an example) BUCK circuit 101 and at least one ( Figure 1 (Taking one as an example for demonstration) Voltage Regulator 102; where:

[0069] The input terminal of the BUCK circuit 101 is connected to the corresponding input interface of the DC / DC converter circuit 10. Each input interface of the DC / DC converter circuit 10 is used to connect to a corresponding power supply (as shown in the figure, Input 20). A power supply 20 can be a photovoltaic string or at least two photovoltaic strings connected in parallel, or a battery cluster or at least two battery clusters connected in parallel. Furthermore, the configuration of each power supply 20 can be the same or different, depending on the specific application environment, and all are within the scope of protection of this application. In practical applications, the number of BUCK circuits 101 can be greater than one. Figure 2 The example shown uses N BUCK circuits (BUCK#1, BUCK#2, ..., BUCK#N) 101 as an example. At this time, the input terminal of each BUCK circuit 101 is connected to the corresponding power supply (Input#1, Input#2, ..., Input#N) 20 through the corresponding interface of the input terminal of the DC / DC converter circuit 10.

[0070] The output terminal of the BUCK circuit 101 is connected to the output terminal of the DC / DC converter circuit 10 (whose voltage is...). Figure 1 (as shown in the image). Figure 2As shown, when the number of BUCK circuits 101 is greater than 1, the output terminals of each BUCK circuit 101 are connected in parallel to the output terminal of the DC / DC converter circuit 10. The output terminal of the DC / DC converter circuit 10 can be connected to the DC side of the subsequent DC / AC converter circuit in the photovoltaic inverter system. In practical applications, the output terminals of each BUCK circuit 101 can be connected to the DC side of the DC / AC converter circuit through a DC bus.

[0071] Figure 1 and Figure 2 The following example demonstrates the use of a basic BUCK topology in the BUCK circuit 101. Figure 1 and Figure 2 As shown, the BUCK circuit 101 includes: an inductor (such as...) Figure 1 The L shown, or, as Figure 2 The L1, L2, ..., LN shown in the diagram), and the switching transistors (such as... Figure 1 The S shown, or, as in Figure 2 The S1, S2, ..., SN shown in the figure) and diodes (such as Figure 1 The D shown, or, as in Figure 2 D1, D2, ..., DN are shown in the diagram; wherein, the diode is connected between the positive and negative transmission branches of the BUCK circuit 101, the inductor is disposed between the input terminal of the BUCK circuit 101 and the diode, and the switching transistor is disposed between the diode and the output terminal of the BUCK circuit 101 as a power switching device.

[0072] The switching transistor can be a MOSFET or an IGBT, etc., and there is no limitation here. Its second terminal can specifically be... Figure 1 or Figure 2 The emitter shown is not limited to this; other implementations in related technologies are also within the scope of protection of this application.

[0073] Additionally, the diodes between the positive and negative transmission branches in the BUCK circuit 101 are connected in series with the corresponding voltage regulator 102. For example... Figure 1 As shown, diode D and voltage regulator 102 are connected in series between the positive and negative transmission branches of the BUCK circuit 101; in practical applications, the series connection order of voltage regulator 102 and diode D is not limited; for example, voltage regulator 102 can be connected between the cathode and negative transmission branches of diode D (e.g. Figure 1 or Figure 2 As shown in the image), it can also be found in (as shown in the image). Figure 1 or Figure 2 A voltage regulator 102 (not shown) is connected between the anode and the positive transmission branch (as shown in the figure); this is not limited here, and can be determined according to the specific application environment, and all are within the protection scope of this application.

[0074] by Figure 1 Taking the structure shown as an example, the input voltage of the BUCK circuit 101 is Vin, and the output voltage is Vout. If there is no voltage regulator 102, then: when the switch S is off, the voltage across the inductor L is the input voltage Vin; when the switch S is on, the voltage across the switch S is the output voltage Vout. And for... Figure 1 The scenario shown illustrates a situation where a voltage regulator 102 is connected in series with a switching transistor S. Assuming the operating voltage of the voltage regulator 102 is V0, then: When the switching transistor S is off, the voltage across the inductor L is Vin - V0, which effectively reduces the voltage across the inductor L as the current increases. This reduces the rate of change of the inductor current, thereby reducing the ripple rate and allowing the selection of a device with a smaller inductance value. When the switching transistor S is on, the voltage across it is Vout - V0, which also reduces the voltage that the switching transistor S needs to withstand, allowing the selection of a power switching device with a lower voltage tolerance. For Figure 2 The principle of each BUCK circuit 101 shown is the same, and will not be described again.

[0075] It can be seen that by controlling the voltage V0 of the voltage regulator 102, the inductor current ripple rate and the voltage amplitude that the power switching device needs to withstand can be controlled. This embodiment does not limit the voltage V0 of the voltage regulator 102; as long as V0 > 0, the inductor current ripple rate and the voltage amplitude that the power switching device needs to withstand can be reduced. When the voltage V0 of the voltage regulator 102 is large, not only can the inductor current ripple rate be significantly reduced, but the voltage that the switching transistor S needs to withstand during operation can even be much lower than half of the system voltage level, which is beneficial for device selection.

[0076] The DC / DC converter circuit provided in this embodiment, through the above-described principle, can reduce the ripple rate of the inductor current, allowing the selection of inductors with smaller inductance values; moreover, it can reduce the voltage across the switching transistor, allowing the selection of power switching devices with lower voltage withstand levels; furthermore, the DC / DC converter circuit can be flexibly selected according to cost requirements and application scenarios.

[0077] In addition, smaller inductors and lower voltage-rated switching transistors can be selected to reduce the cost of the DC / DC converter circuit; the more parallel circuits of the BUCK circuit 101 in the DC / DC converter circuit, the greater the cost advantage of the DC / DC converter circuit.

[0078] In practical applications, the BUCK circuit 101 can adopt either a common negative terminal structure or a common positive terminal structure. Under the common negative terminal structure, such as... Figure 1 or Figure 2As shown, the input and output terminals of the BUCK circuit 101 share a common negative terminal (its potential is...). Figure 1 and Figure 2 The Vcom shown refers to the negative input terminal and the negative output terminal of the BUCK circuit 101, which are connected to the negative input terminal and the negative output terminal of the corresponding input circuit interface of the DC / DC converter circuit 10. The positive input terminal of the BUCK circuit 101 is connected to the positive input terminal of the corresponding input circuit interface of the DC / DC converter circuit 10, and can be connected to the positive terminal of the corresponding power supply 20. The positive output terminal of the BUCK circuit 101 is connected to the positive output terminal of the DC / DC converter circuit 10. In addition, the corresponding voltage regulator 102 is connected between the diode and the negative transmission branch in the positive and negative transmission branches of the BUCK circuit 101. Figure 3 Taking the number of BUCK circuits 101 as N as an example, the common positive electrode structure is illustrated, such as... Figure 3 As shown, the input and output terminals of the BUCK circuit 101 share a common positive terminal, meaning that the positive terminals of the input and output terminals of the BUCK circuit 101 are connected to the positive terminals of the corresponding input and output interfaces of the DC / DC converter circuit 10. The negative terminal of the input terminal of the BUCK circuit 101 is connected to the negative terminal of the corresponding input interface of the DC / DC converter circuit 10, and can be connected to the negative terminal of the corresponding power supply 20. The negative terminal of the output terminal of the BUCK circuit 101 is connected to the negative terminal of the output terminal of the DC / DC converter circuit 10. In addition, the corresponding voltage regulator 102 is connected between the diode and the positive transmission branch in the BUCK circuit 101.

[0079] For the common negative electrode structure, please refer to Figure 1 or Figure 2 In this BUCK circuit 101, only the corresponding wires exist in the negative transmission branch, while the inductor and switching transistor inside the BUCK circuit 101 are all located in the positive transmission branch; specifically, taking Figure 1 Taking the BUCK circuit 101 as an example, one end of the inductor L serves as the positive input terminal of the BUCK circuit 101, the other end of the inductor L is connected to the first terminal of the switch S and the anode of the diode D, the second terminal of the switch S is connected to the positive output terminal of the BUCK circuit 101, and the cathode of the diode D is used to connect to the negative transmission branch of the BUCK circuit 101. Figure 2 The internal component connections of each BUCK circuit 101 are the same as those described above, and will not be repeated here.

[0080] For the common cathode structure, please refer to Figure 3 The positive transmission branch of the BUCK circuit 101 contains only the corresponding wires, while the inductor and switching transistor inside the BUCK circuit 101 are located in the negative transmission branch; specifically, taking Figure 3Taking the bottommost BUCK circuit 101 as an example, one end of its inductor L1 serves as the negative input terminal of the BUCK circuit 101, and the other end of the inductor L1 is connected to the second terminal of the switch S1 and the cathode of the diode D1. The first terminal of the switch S1 is connected to the negative output terminal of the BUCK circuit 101, and the anode of the diode D1 is used to connect to the positive transmission branch of the BUCK circuit 101. Figure 3 The internal component connections of other BUCK circuits 101 are the same as those in this circuit, and will not be described in detail here.

[0081] That is, this application does not limit the transmission branch where the inductor and the switching transistor are located in the BUCK circuit 101. They can be in the positive transmission branch or the negative transmission branch.

[0082] Furthermore, the series connection order of the voltage regulator 102 and the diodes in the BUCK circuit 101 is not limited in either structure; for example, for any BUCK circuit 101 in the common cathode structure, a voltage regulator 102 can be connected between the cathode and negative transmission branches of its diodes (e.g., Figure 1 or Figure 2 As shown in the diagram, a voltage regulator 102 (not shown) can also be connected between the anode and positive transmission branch of its diode; for any BUCK circuit 101 in a common positive structure, a voltage regulator 102 (not shown) can be connected between the cathode and negative transmission branch of its diode, or a voltage regulator 102 (as shown in the diagram) can be connected between the anode and positive transmission branch of its diode. Figure 3 (as shown in the image); no limitation is made here, depending on the specific application environment, and all are within the scope of protection of this application.

[0083] In one example, under a common negative electrode structure, such as Figure 1 or Figure 2 As shown, the voltage regulator 102 can be connected between the diode and the negative transmission branch in the BUCK circuit 101, specifically, the positive terminal of the voltage regulator 102 is connected to the cathode of the diode, and the negative terminal of the voltage regulator 102 is connected to the negative transmission branch. In a common positive structure, as... Figure 3 As shown, the voltage regulator 102 can be connected between the diode and the positive transmission branch in the BUCK circuit 101. Specifically, the positive terminal of the voltage regulator 102 is connected to the positive transmission branch, and the negative terminal of the voltage regulator 102 is connected to the anode of the diode. Furthermore, when the number of BUCK circuits 101 is greater than one, the diodes between the positive and negative transmission branches in each BUCK circuit 101 can share the same voltage regulator 102, that is, they are all connected in series with the voltage regulator 102. Figure 2Taking the illustrated example, diode D1 is connected in series with the voltage regulator 102 between the positive and negative transmission branches of the bottommost BUCK circuit 101; diode D2 is connected in series with the voltage regulator 102 between the positive and negative transmission branches of the middle BUCK circuit 101; and so on, with diode DN connected in series with the voltage regulator 102 between the positive and negative transmission branches of the topmost BUCK circuit 101. In this configuration, the number of voltage regulators 102 can be reduced, lowering costs.

[0084] This embodiment does not limit the number of BUCK circuits 101 and voltage regulators 102 in the DC / DC converter circuit 10. That is, the number of BUCK circuits 101 can be greater than 1, and the number of voltage regulators 102 can also be greater than 1. Moreover, there is no mutual influence between the two numbers, which allows the DC / DC converter circuit 10 to have various structures, such as:

[0085] (1) The number of voltage regulators 102 is 1, the number of BUCK circuits 101 is greater than 1, and each BUCK circuit 101 is connected in series with the voltage regulator 102.

[0086] That is, such as Figure 2 or Figure 3 As shown in the figure, this method can save the number of voltage regulators 102 to the greatest extent and reduce costs.

[0087] (2) The number of BUCK circuits 101 is greater than 1, and there are at least two BUCK circuits 101 connected to the same voltage regulator 102.

[0088] In practical applications, if the number N of the BUCK circuits 101 is large, the BUCK circuits 101 can be grouped together to share the voltage regulator 102. That is, the diodes between the positive and negative transmission branches of each BUCK circuit 101 in each group are connected in series with the same voltage regulator 102, and the number of BUCK circuits 101 in each group is not limited. As long as there are at least two BUCK circuits 101 in a group that share the same voltage regulator 102, at least one voltage regulator 102 can be saved, thereby reducing costs.

[0089] (3) The number of voltage regulators 102 is greater than 1, and there is at least one BUCK circuit 101 connected to at least two voltage regulators 102.

[0090] At this time, the number of BUCK circuits 101 can be one or more, as long as the diode between the positive and negative transmission branches in one BUCK circuit 101 is connected in series with at least two voltage regulators 102. Moreover, the voltage regulators 102 connected to the corresponding diodes can be connected in parallel or in series, and the order of series connection is not limited. As long as there are voltage regulators 102 connected in series between the diodes between the positive and negative transmission branches, the ripple rate of the inductor current in the corresponding BUCK circuit 101 can be reduced, and the voltage borne by the corresponding switching transistor can be reduced. It depends on the specific application environment, and all of them are within the protection scope of this application.

[0091] (4) The number of BUCK circuit 101 and voltage regulator 102 is greater than 1, and BUCK circuit 101 and voltage regulator 102 are connected in a one-to-one correspondence.

[0092] That is, the DC / DC converter circuit 10 may include at least two sets of... Figure 1 The structures shown in the figure include a BUCK circuit 101 and a voltage regulator 102 in each group of structures; the output terminals of each BUCK circuit 101 are connected in parallel; moreover, the series connection order between the voltage regulator 102 and the corresponding diode in each group of structures is not limited, and the series connection order in different groups of structures can be the same or different, depending on the specific application environment, and all of them are within the protection scope of this application.

[0093] In addition, a corresponding capacitor (such as...) can be connected between the positive and negative terminals of the input of the BUCK circuit 101. Figure 1 The Cin shown, or, as... Figure 2 or Figure 3 The capacitors C1, C2, ..., CN shown in the diagram are used to filter and stabilize the input voltage of the BUCK circuit 101. Additionally, the output of the DC / DC converter circuit 10 can also be connected to a corresponding capacitor (e.g., ...). Figures 1 to 3 The capacitor Cout shown in the figure is used to filter and stabilize the output voltage Vout of the BUCK circuit 101. The capacitor Cout can belong to the DC / DC converter circuit 10, or it can be connected between the positive and negative terminals of the DC bus. It can also be set in two different positions, depending on the specific application environment. All of these are within the protection scope of this application.

[0094] Due to the voltage divider effect of the voltage regulator 102, the BUCK circuit 101 connected to it only needs one power switching device, that is, the basic BUCK topology described above can be used.

[0095] This application does not limit the structure of the BUCK circuit 101, nor does it limit the quantitative correspondence between the BUCK circuit 101 and the voltage regulator 102; these can be determined according to the specific application environment.

[0096] Based on the above embodiments, this embodiment provides a more detailed description of the DC / DC converter circuit 10. For example, its voltage regulator 102 can be implemented using any device capable of stably controlling the voltage at the corresponding location, i.e., there are multiple implementation forms, such as:

[0097] The voltage regulator 102 can be a voltage regulator chip; the output terminal of the voltage regulator chip is connected in series with the diode in the corresponding BUCK circuit 101 between the positive and negative transmission branches; the output terminal of the voltage regulator chip includes positive and negative terminals, to... Figure 1 The structure shown is used as an example for explanation. The positive terminal of the output of the voltage regulator chip is connected to the cathode of the diode D, and the negative terminal of the output of the voltage regulator chip is connected to the negative transmission branch. Other structures and connection sequences will not be described in detail.

[0098] Alternatively, the voltage regulator 102 can also be a voltage-regulated load; the input terminal of the voltage-regulated load is connected in series with the diode between the positive and negative transmission branches in the corresponding BUCK circuit 101; the input terminal of the voltage-regulated load includes positive and negative terminals, so as to... Figure 1 The structure shown is used as an example for explanation. The positive terminal of the input of the voltage-regulated load is connected to the cathode of the diode D, and the negative terminal of the input of the voltage-regulated load is connected to the negative transmission branch. Other structures and connection sequences will not be described in detail.

[0099] Alternatively, the voltage regulator 102 may also include a BOOST circuit, such as Figure 4 The BOOST circuit shown in the diagram serves as the two ends of the voltage regulator 102, connected in series with the diodes in the positive and negative transmission branches of the BUCK circuit 101. The output of the BOOST circuit can be connected to the output of the DC / DC converter circuit 10 (e.g., ...). Figure 4 (as shown in the image).

[0100] In practical applications, this BOOST circuit can be a two-level BOOST topology, for example... Figure 4 The basic BOOST topology shown includes an inductor L0, a switch S0, and a diode D0. The switch S0, acting as a power switch, is connected between the positive and negative transmission branches of the BOOST circuit. The inductor L0 is positioned between the input terminal of the BOOST circuit and the switch S0, and the diode D0 is positioned between the switch S0 and the output terminal of the BOOST circuit. Furthermore, the BOOST circuit can also be a common negative or common positive structure. Figure 4 The example shown uses a common negative electrode structure, where the inductor L0 and diode D0 are placed in the positive electrode transmission branch (e.g., Figure 4(As shown in the diagram); In the common positive terminal structure, the inductor L0 and diode D0 are placed in the negative terminal transmission branch (not shown). In addition, a corresponding capacitor C0 can also be placed between the positive and negative terminals of the input of this BOOST circuit.

[0101] Figure 4 Taking a BUCK circuit 101 with two units and a common negative terminal structure as an example, its specific operating states include:

[0102] When the switching transistor S0 is turned on, it can form as follows: Figure 5 In the circuit indicated by the dashed arrow, inductor L0 is charged, and capacitor C0 in voltage regulator 102 is discharged.

[0103] When the switching transistor S0 is turned off, it can form as follows: Figure 6 In the circuit indicated by the dashed arrow, inductor L0 is discharging, and capacitor C0 in voltage regulator 102 is discharging.

[0104] When the switching transistor S1 is turned on, it can form as follows: Figure 7 The loop indicated by the dashed arrow shows inductor L1 discharging.

[0105] When the switching transistor S1 is turned off, the following can be formed: Figure 8 The loop indicated by the dashed arrow shows the inductor L1 and the capacitor C0 in the voltage regulator 102 being charged.

[0106] When the switching transistor S2 is turned on, it can form as follows: Figure 9 The loop indicated by the dashed arrow shows inductor L2 discharging.

[0107] When switch S2 is turned off, the following can be formed: Figure 10 The loop indicated by the dashed arrow shows the inductor L2 and the capacitor C0 in the voltage regulator 102 being charged.

[0108] Additionally, the DC / DC converter circuit 10 may also include at least one unidirectional conducting device, such as... Figures 4 to 10 The diodes DS1 and DS2 shown are connected in series with the switching transistors in the corresponding BUCK circuit 101. That is, each switching transistor in the BUCK circuit 101 is connected in series with a corresponding unidirectional conducting device.

[0109] like Figure 4As shown, diode DS1 is connected in series with switch S1, and diode DS2 is connected in series with switch S2; the conduction direction of this unidirectional conducting device is the direction of the current flowing when the switch in the connected BUCK circuit 101 is controlled to conduct. The same principle applies to cases with a larger number of BUCK circuits 101, and will not be elaborated further. In this case, even if the output voltage of the BOOST circuit is higher than the output voltage of any BUCK circuit 101, the parallel connection of their outputs will not cause reverse current to the corresponding BUCK circuit 101.

[0110] In practical photovoltaic system applications, various power sources (such as...) Figure 2 or Figure 3 The Input#1, Input#2, ..., Input#N shown, or, Figures 4 to 10 When the input characteristics of Input#1 and Input#2)20 shown are not much different, a high-voltage, high-power regulated power supply 102 can be selected, so that each BUCK circuit 101 can select devices with lower tolerance. The regulated power supply 102 can also be used to perform basic power control of MPPT (Maximum Power Point Tracking), so that each BUCK circuit 101 only needs to make a small adjustment to its input voltage to achieve MPPT for each power supply 20.

[0111] In particular, when the input characteristics of each power supply 20 are basically the same, the switching transistors in each BUCK circuit 101 can be completely turned off, so that the DC / DC converter circuit 10 can achieve MPPT for all power supplies 20 through the voltage regulator 102 alone.

[0112] Therefore, the DC / DC converter circuit 10 provided in this embodiment has significant advantages in hardware selection and software control in application scenarios where the configuration differences of each power supply 20 are small.

[0113] It is worth noting that the conventional BOOST topology used in the front-end DC / DC conversion circuit 10 of the photovoltaic inverter system in related technologies only has a boost function, and its input voltage is less than or equal to the output voltage during operation. However, in some practical application scenarios, due to the excessive configuration of photovoltaic modules or the influence of external environmental factors such as temperature and irradiance, the input voltage may be higher than the normal design range, causing the output voltage to increase along with the input voltage; however, an excessively high output voltage may affect the normal operation of the power converter in the system, such as the inverter.

[0114] The DC / DC converter circuit 10 provided in this embodiment can achieve a boost function through the voltage regulator 102 connected in series with the BUCK circuit 101. It can be applied to application scenarios with high input voltage that affect the constant operation of output voltage, especially in the application scenario of photovoltaic module oversizing. The power converter implemented using this topology can support a higher oversizing factor of photovoltaic modules and increase the power generation of photovoltaic power plants.

[0115] In practical applications, the output of this BOOST circuit can also be connected to a battery or load circuit (not shown in the figure), which is not limited here. This allows for voltage regulation of the battery or load circuit, or the provision of a suitable power supply voltage to the load circuit.

[0116] In addition, this BOOST circuit can also be a three-level BOOST topology. Figure 11 In Figure 4 (Based on this, the BOOST circuit is replaced with a three-level flying capacitor BOOST topology as an example.) The specific implementation of the voltage regulator 102 is not limited in this application; it depends on the specific application environment. As long as the ripple rate of the inductor current and the voltage that the switching transistor withstands can be reduced, it is within the protection scope of this application.

[0117] Another embodiment of this application provides a control method for a DC / DC converter circuit, which includes at least one BUCK circuit and at least one voltage regulator; the diodes between the positive and negative transmission branches in the BUCK circuit are connected in series with the corresponding voltage regulator; the structure and principle of the DC / DC converter circuit can be found in the above embodiments, and will not be repeated here.

[0118] like Figure 12 As shown, the control method for this DC / DC converter circuit includes:

[0119] S101. Control the operation of the voltage regulator with the preset voltage as the target.

[0120] Specifically, S101 may include: a voltage control target with a preset voltage as the voltage regulator source, controlling the operation of the voltage regulator source so that it undertakes the preset portion of the input voltage of the BUCK circuit to which it is connected.

[0121] Taking the application scenario of a photovoltaic inverter system as an example, the voltage regulator can be controlled to bear a preset part of the input voltage of the BUCK circuit it is connected to, such as a larger part of the corresponding input voltage, so that the voltage regulator operates at the preset voltage or a certain range near it, thereby making the photovoltaic string connected to the corresponding BUCK circuit move closer to its maximum power point.

[0122] Furthermore, when executing S101, for cases where at least two BUCK circuits share the same voltage regulator, the voltage regulator is controlled to bear a preset portion of the input voltage of the BUCK circuits it is connected to. Specifically, this process may include: controlling the voltage of the voltage regulator to be the minimum input voltage of all the BUCK circuits currently connected to it. That is, the preset voltage may refer to the minimum input voltage of each corresponding BUCK circuit.

[0123] Alternatively, in photovoltaic inverter system applications, the MPP voltage of each photovoltaic string can be determined under different lighting conditions through prior experiments or real-time monitoring, based on the configuration of each string. For each lighting condition, a suitable voltage value, such as the minimum value, can be selected from the MPP voltages of all strings sharing the same voltage regulator. This minimum value is then used as the preset value for that voltage regulator under the corresponding lighting conditions, thus bearing a larger portion of the MPP voltage. In other words, this preset voltage can also be the preset value corresponding to the current lighting conditions.

[0124] In practical applications, other methods can also be used to control the operation of the voltage regulator. These are just some optional examples and are not limited to these.

[0125] Through S101, most of the power required for MPPT is achieved by the BUCK circuit connected to the voltage regulator, thus enabling the BUCK circuit to achieve MPPT with less power. This applies to cases where the diodes between the positive and negative transmission branches of at least two BUCK circuits are connected in series with the same voltage regulator, for example... Figure 2 or Figure 3 As shown, the power corresponding to the above operation of the voltage regulator is also the sum of most of the power when each BUCK circuit implements MPPT; thus, each BUCK circuit can achieve MPPT with less power by sharing the same voltage regulator.

[0126] S102, controls the operation of the BUCK circuit.

[0127] When the power supply connected to the input of the BUCK circuit includes one photovoltaic string or at least two photovoltaic strings connected in parallel, the specific objective of S102 is to enable the BUCK circuit to operate at the MPP of its connected power supply. In practical applications, the power supply connected to the input of the BUCK circuit may also include one battery cluster or at least two battery clusters connected in parallel; this is not limited here and depends on the specific application environment.

[0128] In practical applications, S102 can specifically include the following two cases:

[0129] (1) If the input voltage of the BUCK circuit is greater than the voltage of the voltage regulator connected to the BUCK circuit, then control the corresponding BUCK circuit to adjust its own input voltage.

[0130] Taking a BUCK circuit whose input terminal is connected to a power source including one photovoltaic string or at least two photovoltaic strings connected in parallel as an example, under normal operating conditions, the BUCK circuit is in MPPT mode, and its input voltage is the MPP voltage of the corresponding photovoltaic string connected to it. With the voltage regulator connected to the BUCK circuit bearing most of its input voltage, by controlling the operation of the BUCK circuit, the voltage across the series connection of its inductor and diode can be changed, thereby fine-tuning the input voltage of the BUCK circuit so that its input voltage equals the corresponding MPP voltage, thus enabling the BUCK circuit to achieve MPPT.

[0131] In practical applications, controlling the BUCK circuit to adjust its input voltage can employ various methods such as the perturbation and observation method, the incremental conductance method, and the constant voltage method. This embodiment does not limit the specific method by which the BUCK circuit adjusts its input voltage; it can be determined according to the specific application environment, and all are within the scope of protection of this application. Moreover, the specific methods of the perturbation and observation method, the incremental conductance method, and the constant voltage method can be found in related technologies, and will not be elaborated here.

[0132] Controlling the BUCK circuit to adjust its input voltage can specifically include controlling the chopping action of the switching transistors within the BUCK circuit. For detailed control procedures, please refer to relevant technical documents; they will not be elaborated upon here.

[0133] (2) If there are at least two BUCK circuits sharing the same voltage regulator and the input characteristics of each BUCK circuit meet the preset consistency condition, or if the voltage of the voltage regulator connected to the BUCK circuit is equal to the MPP voltage of the power supply connected to the BUCK circuit, then the switching transistor in the corresponding BUCK circuit is controlled to be normally off.

[0134] In cases where the diodes between the positive and negative transmission branches in at least two BUCK circuits are connected in series with the same voltage regulator, if the input characteristics of each photovoltaic string are basically the same, that is, if the preset consistency condition is met, then the switching transistors in each BUCK circuit can be completely turned off, that is, each switching transistor can be controlled to be normally off, thereby achieving MPPT for each photovoltaic string connected to it with the same voltage regulator, further reducing the control complexity of the software.

[0135] When the diodes between the positive and negative transmission branches of at least two BUCK circuits are connected in series with the same voltage regulator, and if the input characteristics of the corresponding photovoltaic strings differ, the input voltage of the BUCK circuit connected to the photovoltaic string with the worst input characteristic will be the lowest. The switching transistor in this BUCK circuit can also be normally off, as long as the voltage of the voltage regulator connected to this BUCK circuit is set to the input voltage of this BUCK circuit. This control method can also be used when a voltage regulator is connected to only one BUCK circuit.

[0136] Even if the power source is not a photovoltaic string, the presence of this voltage regulator can still bear a portion of the input voltage of the BUCK circuit it is connected to. Its control principle is similar and will not be described in detail here.

[0137] The control method for the DC / DC converter circuit provided in this embodiment allows the BUCK circuit to have most of its power and input voltage handled by its connected voltage regulator, thereby reducing the ripple rate of the inductor current and the voltage across the switching transistor, allowing for the selection of lower-specification components for the inductor and switching transistor. For multiple BUCK circuits sharing the same voltage regulator, this significantly reduces hardware costs while also lowering software control complexity.

[0138] Another embodiment of this application also provides a controller, such as Figure 13 As shown, the controller may include a memory 301 and a processor 302. The processor 302 may be connected to the DC / DC converter circuit 10 provided in the above embodiment and may drive the switching transistors in the DC / DC converter circuit 10.

[0139] The memory 301 can specifically be RAM (random access memory), flash memory, ROM (read only memory), EPROM (Electronic Programmable ROM, a type of non-volatile read-only memory), registers, hard disks, removable disks, etc.

[0140] The memory 301 is used to store computer instructions. When the computer instructions stored in the memory 301 are executed by the processor 302, the processor 302 can be used to execute the control method of the DC / DC conversion circuit described in any of the above embodiments. The memory 301 can also store data, such as preset voltage and other information involved in the above embodiments.

[0141] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, DSL (digital subscriber line)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media, such as floppy disks, hard disks, and magnetic tapes; or, the available media can be semiconductor media, such as SSDs (solid state disks); the available media can also be other media, without limitation.

[0142] Another embodiment of this application also provides a power converter, such as Figure 14 As shown, it includes: a controller 01 and a DC / DC converter circuit 10; wherein:

[0143] The input terminal of the DC / DC converter circuit 10 is used to connect at least one power supply. Figure 14 (Taking multiple power supply Input#1 to Input#N as an example for demonstration) 20, the input terminal of the DC / DC conversion circuit 10 can be provided with multiple interfaces, each interface is connected to one power supply 20. One power supply 20 may include one photovoltaic string or at least two photovoltaic strings connected in parallel, or one power supply 20 may also include one battery cluster or at least two battery clusters connected in parallel. There is no limitation here, it depends on the specific application environment.

[0144] The output of the DC / DC converter circuit 10 can be connected to the DC bus of the inverter system.

[0145] The specific structure and working principle of the DC / DC converter circuit 10 can be found in the above embodiments, and will not be repeated here.

[0146] In addition, the DC / DC converter circuit 10 is controlled by the controller 01; the controller 01 is used to execute the control method of the DC / DC converter circuit as described in any of the above embodiments; the specific process and principle of the control method of the DC / DC converter circuit can be found in the above embodiments, and will not be repeated here.

[0147] In practical applications, this power converter may also include Figure 15 The diagram shows a DC / AC converter circuit 30. The DC side of this DC / AC converter circuit 30 is connected to the output terminal of the DC / DC converter circuit 10. When multiple BUCK circuits exist in the DC / DC converter circuit 10, the output terminals of each BUCK circuit can be connected in parallel to the DC side of the DC / AC converter circuit 30 via a DC bus. The AC side of the DC / AC converter circuit 30 is used to connect to the power grid and / or load. The AC side of the DC / AC converter circuit 30 can be used to output three-phase AC power (as shown in the diagram) or single-phase AC power (not shown), both of which are within the scope of protection of this application. The DC / AC converter circuit 30 is controlled by a controller 01 to realize the inverter function of the electrical energy output from the DC / DC converter circuit 10.

[0148] Figure 14 The power converter shown in the diagram can be used as an intelligent combiner box in a photovoltaic inverter system, or as an energy storage DC / DC converter connected to the DC bus of the photovoltaic inverter in a photovoltaic-storage system. Figure 15 The power converter shown in the diagram can be used as a string inverter in a photovoltaic inverter system, or as an energy storage converter in an energy storage system or a photovoltaic-energy storage system; however, it is not limited to these and can be used depending on the specific application environment.

[0149] In practical applications, the controller 01 can be a single unit or it can include multiple communication-connected modules (such as...). Figure 16 or Figure 17 The control module 02 shown is as follows; Figure 16 or Figure 17 As shown, when the controller 01 includes multiple control modules 02, the voltage regulator 102 and the BUCK circuit 101 in the DC / DC converter circuit 10 are integrated with their respective control modules 02 in their respective device housings and are controlled by their respective control modules 02. For example, the BUCK circuit 101 can be integrated with the corresponding control module 02 in one DC / DC converter, and when the voltage regulator 102 uses a BOOST circuit, it can also be integrated with the corresponding control module 02 in another DC / DC converter. Figure 16 exist Figure 14 The connection relationship of the BUCK circuit 101 with a common negative structure is used as an example to illustrate the connection relationship. However, the actual application is not limited to this.

[0150] In this case, Figure 15 The DC / AC conversion circuit 30 shown will also be integrated with the corresponding control module in the corresponding device housing, such as Figure 17 The DC / AC converter 31 shown is described; the control module inside the DC / AC converter 31 can communicate with each control module 02.

[0151] The power converter provided in this embodiment, by employing the DC / DC conversion circuit 10 described in the above embodiment, can reduce hardware costs and support higher oversizing coefficients for photovoltaic modules, thereby increasing the power generation of photovoltaic power plants; by employing the control method of the DC / DC conversion circuit described in the above embodiment, the control complexity of the software can be reduced.

[0152] Similar or identical parts between the various embodiments in this specification can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the description of the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment solution according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0153] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0154] The features described above regarding the disclosed embodiments can be substituted for or combined with each other to enable those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A DC / DC converter circuit, characterized in that, include: At least one BUCK circuit and at least one voltage regulator; wherein, The input terminal of the BUCK circuit is connected to the corresponding input interface of the DC / DC converter circuit. The output terminal of the BUCK circuit is connected to the output terminal of the DC / DC converter circuit. In the BUCK circuit, the diodes between the positive and negative transmission branches are connected in series with the corresponding voltage regulators.

2. The DC / DC converter circuit according to claim 1, characterized in that, The number of the BUCK circuit and the voltage regulator is greater than 1, and the BUCK circuit and the voltage regulator are connected in a one-to-one correspondence. Alternatively, the number of voltage regulators is greater than 1, and at least one of the BUCK circuits is connected to at least two voltage regulators; Alternatively, the number of BUCK circuits is greater than 1, and at least two of the BUCK circuits are connected to the same voltage regulator. Alternatively, the number of voltage regulators is 1, the number of BUCK circuits is greater than 1, and each BUCK circuit is connected in series with the voltage regulator.

3. The DC / DC converter circuit according to claim 1, characterized in that, The voltage regulator includes: a voltage regulator chip; the output terminal of the voltage regulator chip is connected in series with the diode between the positive and negative transmission branches in the corresponding BUCK circuit; Alternatively, the voltage regulator may include: a voltage regulator load; the input terminal of the voltage regulator load is connected in series with a diode between the positive and negative transmission branches in the corresponding BUCK circuit; Alternatively, the voltage regulator may include a BOOST circuit; the input terminal of the BOOST circuit is connected in series with a diode between the positive and negative transmission branches in the BUCK circuit.

4. The DC / DC converter circuit according to claim 3, characterized in that, The output terminal of the BOOST circuit is connected to the output terminal of the DC / DC converter circuit. Alternatively, the output of the BOOST circuit can be connected to a battery or load circuit.

5. The DC / DC converter circuit according to claim 3, characterized in that, The BOOST circuit is either a two-level BOOST topology or a three-level BOOST topology.

6. The DC / DC converter circuit according to any one of claims 1 to 5, characterized in that, Also includes: At least one unidirectional conducting device; The unidirectional conducting device is connected in series with the switching transistor in the BUCK circuit; The conduction direction of the unidirectional conducting device is the direction of the current flowing when the connected switch is controlled to conduct.

7. The DC / DC converter circuit according to any one of claims 1 to 5, characterized in that, The positive input terminal of the BUCK circuit is connected to the positive input terminal of the corresponding input interface of the DC / DC converter circuit, the positive output terminal of the BUCK circuit is connected to the positive output terminal of the DC / DC converter circuit, the negative input terminal and the negative output terminal of the BUCK circuit are connected to the negative input terminal and the negative output terminal of the DC / DC converter circuit, and the voltage regulator is connected between the diode and the negative transmission branch in the positive and negative transmission branches of the BUCK circuit. Alternatively, the negative input terminal of the BUCK circuit is connected to the negative input terminal of the corresponding input interface of the DC / DC converter circuit, the negative output terminal of the BUCK circuit is connected to the negative output terminal of the DC / DC converter circuit, the positive input terminal and the positive output terminal of the BUCK circuit are connected to the positive input terminal and the positive output terminal of the DC / DC converter circuit, and the corresponding voltage regulator is connected between the diode and the positive transmission branch in the BUCK circuit.

8. A control method for a DC / DC converter circuit, characterized in that, include: With a preset voltage as the target, the voltage regulator is controlled to operate by the diodes connected in series between the DC / DC converter circuit and the positive and negative transmission branches in the BUCK circuit; Control the operation of the BUCK circuit.

9. The control method for the DC / DC converter circuit according to claim 8, characterized in that, The objective of controlling the operation of the BUCK circuit is to make the BUCK circuit operate at the maximum power point of the power supply it is connected to.

10. The control method for the DC / DC converter circuit according to claim 8, characterized in that, Controlling the operation of the BUCK circuit includes: If the input voltage of the BUCK circuit is greater than the voltage of the voltage regulator connected to the BUCK circuit, then the BUCK circuit is controlled to adjust its own input voltage. If at least two of the BUCK circuits share the same voltage regulator and the input characteristics of each BUCK circuit meet a preset consistency condition, or if the voltage of the voltage regulator connected to the BUCK circuit is equal to the maximum power point voltage of the power supply connected to the BUCK circuit, then the switching transistor in the BUCK circuit is controlled to be normally off.

11. The control method for the DC / DC converter circuit according to claim 10, characterized in that, Controlling the BUCK circuit to adjust its input voltage includes: Control the chopping action of the switching transistor in the BUCK circuit.

12. The control method for the DC / DC converter circuit according to any one of claims 8 to 11, characterized in that, The operation of a voltage regulator, controlled by a diode connected in series between the DC / DC converter circuit and the positive and negative transmission branches in the BUCK circuit, with a preset voltage as the target, includes: Using the preset voltage as the voltage control target of the voltage regulator, the voltage regulator is controlled to operate so that it bears the preset portion of the input voltage of the BUCK circuit to which it is connected.

13. The control method for the DC / DC converter circuit according to claim 12, characterized in that, When at least two of the aforementioned BUCK circuits share the same voltage regulator, the preset voltage is: The minimum input voltage of all the BUCK circuits currently connected to the voltage regulator; Alternatively, if the power supply connected to the BUCK circuit includes a photovoltaic module, the preset value corresponding to the current illumination conditions.

14. A controller, characterized in that, include: A processor and a memory, the memory being used to store programs, instructions, or code, and the processor being used to execute the programs, instructions, or code in the memory to perform the control method for the DC / DC converter circuit as described in any one of claims 8 to 13.

15. A power converter, characterized in that, include: The controller and the DC / DC conversion circuit as described in any one of claims 1 to 7; wherein, The DC / DC conversion circuit is controlled by the controller; The controller is used to execute the control method for the DC / DC conversion circuit as described in any one of claims 8 to 13.

16. The power converter according to claim 15, characterized in that, Also includes: DC / AC conversion circuit; The DC side of the DC / AC conversion circuit is connected to the output terminal of the DC / DC conversion circuit; The AC side of the DC / AC conversion circuit is used to connect to the power grid and / or the load; The DC / AC conversion circuit is controlled by the controller.

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