Charging circuits and charging equipment

Abstract

This application relates to the field of charging system technology, and more particularly to a charging circuit and charging device. The charging circuit includes an AC switching circuit, a filter circuit, and at least two parallel power conversion circuits. The AC switching circuit is used to connect to the AC power grid and control the input and output of AC power. The filter circuit is electrically connected to the AC switching circuit and is used to filter the AC power flowing through it. Each of the at least two parallel power conversion circuits is electrically connected to the filter circuit, and the power conversion circuits are used to convert between AC and DC power and to convert the voltage of DC power. The charging circuit of this application reduces circuit size and saves costs by having all power conversion circuits share the AC switching circuit and filter circuit on the AC side.

Description

Technical Field

[0001] This application relates to the field of charging system technology, and in particular to a charging circuit and charging device. Background Technology

[0002] Please see Figure 1 Most high-power electric vehicle charging stations have at least two charging ports (e.g., Figure 1 The D1 and D2 components are powered through an AC input port A1, and after power conversion by the power conversion circuit, the power is output through the charging port so as to charge multiple vehicles simultaneously.

[0003] One commonly used charging circuit design on the market uses an AC input port, with AC power output to various power conversion circuits. Each power conversion circuit performs power conversion before outputting the final power. Each power conversion circuit has a corresponding AC switching circuit and filtering circuit before its output. In this design, each charging module has its own independent and complete circuitry and structure. When multiple charging modules need to work together (e.g., in parallel or series) to increase power output, cables and connectors are required to achieve electrical connections and signal communication between the modules. This results in relatively high costs and a lower overall power density, which is not conducive to reducing size. Utility Model Content

[0004] One objective of this application is to provide a charging circuit and charging device to solve the technical problems of high cost and low overall power density in existing charging circuit solutions.

[0005] In a first aspect, embodiments of this application provide a charging circuit, comprising:

[0006] An AC switching circuit is used to connect to the AC power grid and control the input and output of AC power.

[0007] A filter circuit, electrically connected to the AC switching circuit, is used to filter the AC current flowing through the filter circuit; and

[0008] At least two parallel power conversion circuits are provided, each of which is electrically connected to the filter circuit. The power conversion circuits are used to perform AC-DC conversion and DC voltage conversion.

[0009] Optionally, the power conversion circuit includes:

[0010] An AC-DC conversion module, electrically connected to the filter circuit, is used to convert between AC and DC power; and

[0011] A DC-DC converter module, which is electrically connected to the AC-DC converter module, is used to perform voltage conversion of direct current.

[0012] Optionally, the AC-DC conversion module is a bidirectional AC-DC converter, and / or the DC-DC conversion module is a bidirectional DC-DC converter.

[0013] Optionally, the charging circuit further includes a bus parallel switch circuit. In any of the power conversion circuits, a DC bus is provided between the AC-DC conversion module and the DC-DC conversion module, and they are interconnected through the DC bus. At least two of the DC buses are respectively connected to the bus parallel switch circuit, and the bus parallel switch circuit can control the at least two connected DC buses to be connected in parallel.

[0014] Optionally, the bus parallel switch circuit includes at least one bus parallel switch, each bus parallel switch is connected to two corresponding DC buses, and the two DC buses connected to each bus parallel switch are located in different power conversion circuits. The bus parallel switch is used to connect the two corresponding DC buses in parallel when it is turned on.

[0015] Optionally, the charging circuit further includes a series-parallel switching circuit. The DC-DC conversion module includes at least two DC-DC conversion units, each of which is electrically connected to the AC-DC conversion module. The at least two DC-DC conversion units are respectively connected to the series-parallel switching circuit, which enables at least two DC-DC conversion units in the same DC-DC conversion module to be connected in series or in parallel.

[0016] Optionally, the series-parallel switching circuit includes at least one single-pole single-throw switch and at least one single-pole double-throw switch, one end of each single-pole single-throw switch is connected to the negative terminal of a corresponding DC-DC converter unit, and the other end of each single-pole single-throw switch is connected to the negative terminal of another corresponding DC-DC converter unit.

[0017] The single-pole double-throw switch includes a movable terminal, a first fixed terminal, and a second fixed terminal. The movable terminal of each single-pole double-throw switch is connected to the positive terminal of a corresponding DC-DC converter unit. The first fixed terminal of each single-pole double-throw switch is connected to the positive terminal of a corresponding DC-DC converter unit. The DC-DC converter unit connected to the first fixed terminal and the second fixed terminal of the single-pole double-throw switch is the same.

[0018] Optionally, the charging circuit further includes a control circuit, which is electrically connected to the AC switching circuit and each of the power conversion circuits, and is used to control the AC switching circuit and each of the power conversion circuits.

[0019] Optionally, the charging circuit further includes an auxiliary power source circuit, which is electrically connected to each of the power conversion circuits and the control circuits, and is used to provide auxiliary power to each of the power conversion circuits and the control circuits.

[0020] In a second aspect, embodiments of this application also provide a charging device, including at least one charging circuit as described in any of the preceding claims.

[0021] The embodiments of this application achieve the following technical effects: In the charging circuit of this application embodiment, the AC switching circuit receives AC power from the grid side and outputs the AC power to the filtering circuit for filtering. After filtering, the filtering circuit outputs the AC power to each power conversion circuit, so that the power conversion circuit performs power conversion on the AC power before outputting it. The charging circuit of this application embodiment reduces the circuit size and saves costs by having each power conversion circuit share the AC switching circuit and the filtering circuit on the AC side. Attached Figure Description

[0022] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings do not constitute a limitation on scale.

[0023] Figure 1 This is a structural block diagram of a charging circuit in the prior art;

[0024] Figure 2 A structural block diagram of a charging circuit provided in an embodiment of this application;

[0025] Figure 3 This is a block diagram of another charging circuit in the prior art;

[0026] Figure 4 A schematic diagram of a bus parallel switch circuit for a charging circuit provided in an embodiment of this application;

[0027] Figure 5 A schematic diagram of a DC-DC converter module and a bus parallel switch circuit for a charging circuit provided in an embodiment of this application;

[0028] Figure 6 A schematic diagram showing a portion of the DC-DC converter units connected in series in a charging circuit according to an embodiment of this application;

[0029] Figure 7 This is a schematic diagram of a charging circuit in which some DC-DC conversion units are connected in parallel, as provided in an embodiment of this application. Detailed Implementation

[0030] To facilitate understanding of this utility model, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as "connected" to another element, it can be directly on the other element, or one or more intermediate elements can exist between them. The terms "upper," "lower," "left," "right," "upper end," "lower end," "top," and "bottom," etc., used in this specification indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention.

[0032] Please see Figure 2 In a first aspect, embodiments of this application provide a charging circuit 100, including an AC switching circuit 10, a filter circuit 20, and at least two parallel power conversion circuits 30. The AC switching circuit 10 is used to connect to the AC power grid and control the input and output of AC power. The filter circuit 20 is electrically connected to the AC switching circuit 10 and is used to filter the AC power flowing through the filter circuit 20. Each of the at least two parallel power conversion circuits 30 is electrically connected to the filter circuit 20, and the power conversion circuits 30 are used to perform AC-DC conversion and DC voltage conversion.

[0033] The working principle of the charging circuit 100 in this embodiment is as follows: the AC switch circuit 10 receives AC power from the grid side and outputs the AC power to the filter circuit 20 for filtering. After filtering, the filter circuit 20 outputs the AC power to each power conversion circuit 30, so that the power conversion circuit 30 performs power conversion on the AC power and outputs it.

[0034] It is understood that the charging circuit 100 of this application embodiment can reduce the circuit size and save costs by sharing the AC switching circuit 10 and the filter circuit 20 on the AC side.

[0035] The AC switching circuit 10 is a circuit used to control the switching on and off of AC power. Specifically, the switch used in the AC switching circuit 10 can be a mechanical relay switch, a solid-state relay, etc., to control the input and output of AC power. Correspondingly, the charging circuit 100 has an AC port A1 for connecting to the AC power grid in the AC switching circuit 10, and DC ports D1 and D2 for connecting to the power switching matrix in the power conversion circuit 30. The power switching matrix is ​​equipped with a charging port for connecting to the load or energy storage power source.

[0036] In some embodiments, the filter circuit 20 is an EMI (Electromagnetic Interference) filter circuit, used to suppress electromagnetic interference in the charging circuit 100, thereby preventing electromagnetic noise inside the charging circuit 100 from affecting the normal operation of other circuits, and preventing interference generated by the charging circuit 100 itself from being conducted to external power supplies or other devices.

[0037] In some embodiments, the power conversion circuit 30 includes an AC-DC (alternating current to direct current) conversion module 31 and a DC-DC (direct current to direct current) conversion module 32. The AC-DC conversion module 31 is electrically connected to the filter circuit 20 and is used to convert between AC and DC power. The DC-DC conversion module 32 is electrically connected to the AC-DC conversion module 31 and is used to convert DC power voltage.

[0038] In the charging circuit 100, AC power from the grid side is input through the AC port, passes through the AC switching circuit 10 and the EMI filter circuit 20, and is then output to each AC-DC conversion module 31 to obtain DC power. The DC power then passes through the DC-DC conversion module 32 to obtain transformed DC power, which is then output. In each power conversion circuit 30, a DC bus is configured between the AC-DC conversion module 31 and the DC-DC conversion module 32, and they are interconnected via the DC bus.

[0039] Please see Figure 3 In existing technologies in the related technical field, one structure of the power conversion circuit 30 is that each DC-DC conversion module 32 shares the same AC-DC conversion module 31. Although this scheme achieves circuit sharing, thereby saving space and cost, since the two DC-DC conversion circuits are connected to the same DC bus, their voltages must be equal. Because the charging states of the two charging ports are usually different, that is, the two DC-DC conversion modules 32 are usually in different charging states (voltage / current / power), it is impossible to adjust the bus voltage to make them both operate at the optimal conversion efficiency, thus increasing losses.

[0040] It is understood that, compared with the prior art, the charging circuit 100 of this application embodiment has independent DC buses, and the voltage of the two DC buses can be adjusted separately. It can be optimized according to the working state of the two DC / DC conversion circuits to improve the power conversion efficiency.

[0041] In some embodiments, AC-DC conversion module 31 is a bidirectional AC-DC converter, and / or DC-DC conversion module 32 is a bidirectional DC-DC converter.

[0042] Understandably, in some embodiments, the AC-DC converter module 31 converts AC power input from the grid side into DC power for device charging or power supply. In other embodiments, the bidirectional AC-DC converter module 31 can convert DC power into AC power for feedback to the grid side. Similarly, in some embodiments, the DC-DC converter module 32 converts DC power at one voltage level to DC power at another voltage level for powering downstream devices. In other embodiments, energy can flow from a low voltage end to a high voltage end; exemplarily, the DC port of the charging circuit 100 is also connected to a battery, and the DC-DC converter module 32 reverses the battery's electrical energy to a higher DC bus. The embodiments of this application employ bidirectional AC-DC converters and bidirectional DC-DC converters to achieve bidirectional energy flow, thus making them suitable for different application scenarios.

[0043] Please see Figure 4 In some embodiments, the charging circuit 100 further includes a bus parallel switch circuit 40. In any power conversion circuit 30, a DC bus is provided between the AC-DC conversion module 31 and the DC-DC conversion module 32 and they are interconnected through the DC bus. At least two DC buses are respectively connected to the bus parallel switch circuit 40. The bus parallel switch circuit 40 can control the at least two connected DC buses to be connected in parallel with each other.

[0044] Understandably, this embodiment of the application, by setting up a bus parallel switching circuit 40, enables the DC buses of different power conversion circuits 30 to be connected in parallel, increasing the maximum output power of at least some DC ports. Correspondingly, idle DC buses can be utilized by other power conversion circuits 30, thereby improving the power utilization rate of the charging circuit 100. In specific use, under the control of the bus parallel switching circuit 40, the power conversion circuits 30 can remain connected in parallel or operate independently, thus adapting to different application scenarios.

[0045] Optionally, the bus parallel switch circuit 40 includes at least one bus parallel switch, each bus parallel switch is connected to two corresponding DC buses, and the two DC buses connected to each bus parallel switch are located in different power conversion circuits 30. The bus parallel switch is used to connect the two corresponding DC buses in parallel when it is turned on.

[0046] As can be understood, each bus parallel switch in this embodiment connects to two different DC buses. When the bus parallel switch is open, the two corresponding DC buses operate independently; when the bus parallel switch is closed, the two corresponding DC buses are connected in parallel. The DC buses include a positive DC bus and a negative DC bus. The bus parallel switch includes two sub-switches. One sub-switch connects to the two corresponding positive DC buses belonging to different DC buses, and the other sub-switch connects to the two corresponding negative DC buses belonging to different DC buses. This allows the two DC buses to be connected in parallel when both sub-switches are closed simultaneously, and to operate independently when both sub-switches are open simultaneously.

[0047] For example, the charging circuit 100 includes three DC buses B1, B2, and B3, and the bus parallel switches include bus parallel switches Ka_1, Ka_2, and Ka_3. DC buses B1 and B2 are connected in parallel through bus parallel switch Ka_1, DC buses B1 and B3 are connected in parallel through bus parallel switch Ka_2, and DC buses B2 and B3 are connected in parallel through bus parallel switch Ka_3.

[0048] In some embodiments, the AC-DC conversion modules 31 are interleaved in parallel. Specifically, interleaving control means that the output current waveforms of these AC-DC conversion modules 31 are designed to be staggered by a certain phase angle. This can reduce the fluctuation of the total current, reduce electromagnetic interference (EMI), and improve the stability of the system.

[0049] For example, if there are two AC-DC converter modules 31 with the same switching frequency, but their operating phases differ by 180 degrees within a switching cycle, this can disperse current surges and prevent excessive current in a single converter at any given moment.

[0050] In one embodiment, each DC bus is provided with a corresponding bus parallel switch between each DC bus and any other DC bus, so that each DC bus can be connected in parallel with any other DC bus, thereby improving the expansion capability of the power conversion circuit 30 and increasing the maximum output power of each DC port.

[0051] Please see Figure 5In some embodiments, the charging circuit 100 further includes a series-parallel switching circuit 50, and the DC-DC conversion module 32 includes at least two DC-DC conversion units 321. Each DC-DC conversion unit 321 is electrically connected to the AC-DC conversion module 31. The at least two DC-DC conversion units 321 are respectively connected to the series-parallel switching circuit 50. The series-parallel switching circuit 50 enables at least two DC-DC conversion units 321 in the same DC-DC conversion module 32 to be connected in series or in parallel.

[0052] Understandably, the DC-DC converter module 32 consists of multiple sub-units, each of which is an independent small DC-DC converter capable of outputting a certain voltage and current. To meet the charging requirements of different loads (such as electric vehicles or energy storage devices), the system allows for series or parallel switching of these sub-units at the DC port side by controlling them. This embodiment of the application achieves flexible output voltage and current regulation by modularizing the DC-DC converter circuit and controlling the series-parallel switching of the sub-units through the series-parallel switching circuit 50, thereby adapting to the needs of different loads.

[0053] Optionally, the series-parallel switching circuit 50 includes at least one single-pole single-throw switch and at least one single-pole double-throw switch. One end of each single-pole single-throw switch is connected to the negative terminal of a corresponding DC-DC converter unit 321, and the other end of each single-pole single-throw switch is connected to the negative terminal of another corresponding DC-DC converter unit 321.

[0054] The single-pole double-throw switch includes a movable terminal, a first fixed terminal, and a second fixed terminal. The movable terminal of each single-pole double-throw switch is connected to the positive terminal of a corresponding DC-DC converter unit 321. The first fixed terminal of each single-pole double-throw switch is connected to the positive terminal of another corresponding DC-DC converter unit 321. The DC-DC converter unit 321 connected to the first and second fixed terminals of the single-pole double-throw switch is the same.

[0055] Understandably, in this embodiment, any two DC-DC conversion units 321 are interconnected via a single-pole single-throw switch and a single-pole double-throw switch to achieve independent, series, and parallel switching between them. The series-parallel switching circuit 50 in this embodiment improves the topology flexibility of the charging circuit 100 to adapt to more application scenarios.

[0056] In one embodiment, each DC-DC converter 321 is provided with a corresponding single-pole single-throw switch and a corresponding single-pole double-throw switch between any other DC-DC converter 321, so that each DC-DC converter 321 can be connected in series or parallel with any other DC-DC converter 321, thereby further improving the expansion capability of the power conversion circuit 30 and increasing the maximum output power of each DC port.

[0057] Please refer to the following: Figures 5 to 7 For example, in one circuit topology, the DC-DC converter module 32 includes three DC-DC converter units 321, and the series-parallel switching circuit 50 includes single-pole single-throw switches Kb_1, Kb_2, and Kb_3, and single-pole double-throw switches Kc_1, Kc_2, and Kc_3. One end of the single-pole single-throw switch Kb_1 is connected to the negative terminal of the first DC-DC converter unit 321, and the other end is connected to the negative terminal of the second DC-DC converter unit 321. The movable terminal of the single-pole double-throw switch Kc_1 is connected to the positive terminal of the first DC-DC converter unit 321, the first fixed terminal of the single-pole double-throw switch Kc_1 is connected to the positive terminal of the second DC-DC converter unit 321, and the second fixed terminal of the single-pole double-throw switch Kc_1 is connected to the negative terminal of the second DC-DC converter unit 321. The connection methods of other switches can be found in [reference needed]. Figures 5 to 7 When the first DC-DC converter unit 321 and the second DC-DC converter unit 321 need to be connected in series, the movable end of the single-pole double-throw switch Kc_1 is connected to the second fixed end, so that the first DC-DC converter unit 321 and the second DC-DC converter unit 321 are connected in series; when the first DC-DC converter unit 321 and the second DC-DC converter unit 321 need to be connected in series, the single-pole single-throw switch Kb_1 is closed, and the movable end of the single-pole double-throw switch Kc_1 is connected to the first fixed end, so that the first DC-DC converter unit 321 and the second DC-DC converter unit 321 are connected in parallel.

[0058] Please review Figure 2 In some embodiments, the charging circuit 100 further includes a control circuit 60, which is electrically connected to the AC switch circuit 10 and each power conversion circuit 30, and is used to control the AC switch circuit 10 and each power conversion circuit 30.

[0059] It is understood that the charging circuit 100 in this embodiment of the application is provided with a control circuit 60, which controls the on / off state of each switch in the AC switch circuit 10 to control the input and output of AC power, and controls each conversion module in the power conversion circuit 30 to control the AC-DC conversion and DC voltage conversion.

[0060] Specifically, the control circuit 60 is connected to each AC-DC conversion module 31 and each DC-DC conversion module 32 respectively, and makes the corresponding conversion module work by sending the corresponding drive signal to any conversion module.

[0061] In some embodiments, the control circuit 60 is also connected to the bus parallel switch circuit 40 and the series-parallel switching switch circuit respectively. The control circuit 60 can control any bus parallel switch, any single-pole single-throw switch and any single-pole double-throw switch to realize the parallel connection between each DC bus and the series-parallel switching between each DC-DC conversion unit 321.

[0062] In some embodiments, the control circuit 60 may include at least one chip or integrated circuit, which has logic units and is capable of controlling the AC circuit and the power conversion circuit 30 respectively according to charging requirements.

[0063] In other embodiments, the control circuit 60 may be constructed from two or more chips that can work in coordination with each other. For example, the control circuit 60 may also be constructed from various logic devices, such as general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), microcontrollers, ARM (Acorn RISC Machine) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of these components.

[0064] In other embodiments, the AC switch circuit 10, the power conversion circuit 30, the bus parallel switch circuit 40, and the series-parallel switch circuit 50 can also be controlled by a control module or control device other than the charging circuit 100.

[0065] In some embodiments, the charging circuit 100 further includes an auxiliary power source circuit 70, which is electrically connected to each power conversion circuit 30 and control circuit 60, and is used to provide auxiliary power to each power conversion circuit 30 and control circuit 60.

[0066] It is understood that the charging circuit 100 in this embodiment of the application is provided with an auxiliary power source circuit 70, which can provide a stable auxiliary power supply for the power conversion circuit 30, control circuit 60, etc., to ensure that the charging circuit 100 can operate normally in various working states. In other embodiments, the auxiliary power source circuit 70 can also be connected to auxiliary devices or circuits with low power supply requirements, such as signal processing circuits, communication modules, sensors, etc.

[0067] In some embodiments, the power conversion circuits 30 of the charging circuit 100 share the AC switching circuit 10, the filter circuit 20, the control circuit 60, and the auxiliary source circuit 70, which can reduce the size of the charging circuit 100 and save costs.

[0068] In a second aspect, embodiments of this application also provide a charging device, including at least one of the above-described charging circuits, wherein the charging device may be a charging host in an automotive charging system.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; under the concept of this utility model, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this utility model as described above. For the sake of brevity, they are not provided in detail; although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A charging circuit, characterized by, include: An AC switching circuit is used to connect to the AC power grid and control the input and output of AC power. A filter circuit, which is electrically connected to the AC switch circuit, is used to filter the AC current flowing through the filter circuit. as well as At least two parallel power conversion circuits, each of which is electrically connected to the filter circuit, are used to perform AC-DC conversion and DC voltage conversion. The power conversion circuit includes an AC-DC conversion module and a DC-DC conversion module. The AC-DC conversion module is electrically connected to the filter circuit, and the DC-DC conversion module is electrically connected to the AC-DC conversion module. The charging circuit further includes a bus parallel switch circuit. In any of the power conversion circuits, a DC bus is provided between the AC-DC conversion module and the DC-DC conversion module, and they are interconnected through the DC bus. At least two of the DC buses are respectively connected to the bus parallel switch circuit, and the bus parallel switch circuit can control the at least two connected DC buses to be connected in parallel.

2. The charging circuit of claim 1, wherein, The AC-DC conversion module is used to convert between AC and DC power. The DC-DC converter module is used to perform voltage conversion of direct current.

3. The charging circuit of claim 2, wherein, The AC-DC conversion module is a bidirectional AC-DC converter, and / or the DC-DC conversion module is a bidirectional DC-DC converter.

4. The charging circuit of claim 1, wherein, The bus parallel switch circuit includes at least one bus parallel switch, each of the bus parallel switches is connected to two corresponding DC buses, and the two DC buses connected to each bus parallel switch are located in different power conversion circuits. The bus parallel switch is used to connect the two corresponding DC buses in parallel when it is turned on.

5. The charging circuit of claim 2, wherein, It also includes a series-parallel switching circuit. The DC-DC conversion module includes at least two DC-DC conversion units. Each DC-DC conversion unit is electrically connected to the AC-DC conversion module. At least two DC-DC conversion units are respectively connected to the series-parallel switching circuit. The series-parallel switching circuit enables at least two DC-DC conversion units in the same DC-DC conversion module to be connected in series or in parallel.

6. The charging circuit of claim 5, wherein, The series-parallel switching circuit includes at least one single-pole single-throw switch and at least one single-pole double-throw switch. One end of each single-pole single-throw switch is connected to the negative terminal of a corresponding DC-DC converter unit, and the other end of each single-pole single-throw switch is connected to the negative terminal of another corresponding DC-DC converter unit. The single-pole double-throw switch includes a movable terminal, a first fixed terminal, and a second fixed terminal. The movable terminal of each single-pole double-throw switch is connected to the positive terminal of a corresponding DC-DC converter unit. The first fixed terminal of each single-pole double-throw switch is connected to the positive terminal of a corresponding DC-DC converter unit. The DC-DC converter unit connected to the first fixed terminal and the second fixed terminal of the single-pole double-throw switch is the same.

7. The charging circuit of claim 1, wherein, It also includes a control circuit, which is electrically connected to the AC switching circuit and each of the power conversion circuits, and is used to control the AC switching circuit and each of the power conversion circuits.

8. The charging circuit of claim 1, wherein, It also includes an auxiliary power source circuit, which is electrically connected to each of the power conversion circuits and the control circuits, and is used to provide auxiliary power to each of the power conversion circuits and the control circuits.

9. A charging device, characterized by It includes at least one charging circuit as described in any one of claims 1-8.

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