Long-distance direct-current power transmission circuit structure

Abstract

The invention discloses a long-distance direct-current power transmission circuit structure, which relates to the technical field of direct-current charging equipment and comprises an alternating-current switch, a plurality of AC / DC rectifier modules at a power grid end, a direct-current power transmission cable and a plurality of DC / DC power supply modules at a far end, the number of the AC / DC rectifier modules is M, and the number of the DC / DC power supply modules is 2M. Every two DC / DC power supply modules form a group and are matched with the corresponding AC / DC rectification modules, the alternating current ends of all the AC / DC rectification modules are connected with an alternating current power grid of a power grid end in parallel, the direct current end of each AC / DC rectification module is connected with the two DC / DC power supply modules in the corresponding group, the input ends of the two DC / DC power supply modules in the same group are connected in series, and the output ends of the two DC / DC power supply modules in the same group are connected in parallel to form a direct current output. The 2M DC / DC power supply modules realize M DC outputs. Low-voltage transmission and high-voltage transmission can be switched, high-voltage transmission is adopted in high power, low-voltage transmission is adopted in low power, and the power supply efficiency is improved. High-voltage power transmission of a low-voltage device and low-voltage and low-power power supply can be realized in case of low power, so that the system efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of DC charging equipment, and more specifically to the technical field of a long-distance DC power transmission circuit structure. Background Art

[0002] A charging pile, also known as an electric vehicle charging station or an electric vehicle power supply device, is a device that provides electrical energy for an electric vehicle, enabling the electric vehicle to store sufficient electrical energy to support its operation. The following technologies have been publicly disclosed in existing patents regarding charging circuits:

[0003] The patent with the publication number CN118971304A and the patent name "Charging Pile Circuit and Home Charging Pile" discloses the following content: The charging pile circuit includes a relay circuit, a power supply circuit, an emergency stop circuit, a CP signal generation and detection circuit, and a control circuit. The relay circuit can control the access / disconnection of an external AC power supply. When the external AC power supply is in the access state, the power supply circuit can convert the external AC power supply into a charging power supply for output, and the charging device can charge. Among them, the CP signal generation and detection circuit can generate a stable CP signal for realizing communication interaction with the charging device. The emergency stop circuit can disconnect the connection between the power supply circuit and the external AC power supply in case of a charging fault to ensure charging safety. In this way, the present invention can realize charging of the charging device and communication interaction with the charging device, and can disconnect the external AC power supply in case of a charging fault, with high safety, a simple and reliable circuit, and low cost.

[0004] The patent with the publication number CN113659687A and the patent name "Charging Pile Circuit and Charging Pile" discloses the following content: A charging pile circuit and a charging pile, the charging pile circuit includes: a charging module, the charging module is connected to a mains access interface to form a charging circuit; an energy storage module, the energy storage module is connected to the charging module to form an energy storage circuit, a charging and energy storage circuit, or a discharging circuit; a control module, the control module is communicatively connected to the charging module and the energy storage module respectively. In the technical solution of the present invention, the charging pile circuit includes a charging module and an energy storage module, integrating battery energy storage, discharging to the grid, and charging an electric vehicle into one, and can realize supplementing the electric energy loss generated by the charging module during the charging process through the energy storage module, improving the charging efficiency.

[0005] The charging pile circuits and existing charging piles disclosed in the above patents generally adopt two circuit structures, namely, a split type and an integrated type, and both adopt low-voltage power transmission. The split type uses a DC power transmission method to the charging pile, and the integrated type uses AC power supply to the charging pile. Both have the problem of high cost of transmission lines when the power is large. AC power transmission also has the problem of large voltage drop over long distances. Summary of the Invention

[0006] The object of the present invention is: to solve the above technical problems, the present invention provides a long-distance DC power transmission circuit structure. It can achieve long-distance power transmission for high-power charging piles, reduce the cross-sectional area of transmission lines, lower the transmission cost, and improve the transmission efficiency.

[0007] In order to achieve the above object, the present invention specifically adopts the following technical solutions:

[0008] The present invention provides a long-distance DC power transmission circuit structure, including an AC switch, multiple AC / DC rectification modules at the grid end, a DC power transmission cable, and multiple DC / DC power supply modules at the far end. The number of AC / DC rectification modules is M, and the number of DC / DC power supply modules is 2M. Two DC / DC power supply modules are grouped together and cooperate with the corresponding AC / DC rectification module. The AC ends of all AC / DC rectification modules are connected to the AC grid at the grid end in parallel, and the DC ends of each AC / DC rectification module are connected to a group of two corresponding DC / DC power supply modules. The inputs of the two DC / DC power supply modules in the same group are connected in series, and the outputs are connected in parallel to form a DC output; the 2M DC / DC power supply modules achieve M DC outputs.

[0009] Specifically, this circuit structure can perform low-voltage and high-voltage transmission switching. When the power is high, high-voltage transmission is adopted, and when the power is low, low-voltage transmission is adopted, which improves the high-power supply power and supply distance, and improves the power supply efficiency. For high-voltage transmission of low-voltage components, when the power is low, low-voltage and low-power supply can be used to improve the system efficiency.

[0010] The number of AC / DC rectification modules and DC / DC power supply modules can be increased or decreased according to this circuit structure, which has high flexibility. DC / DC power supply module: a circuit that can perform step-up and step-down control of direct current and two-way control of electric energy, and has electrical isolation function between input and output.

[0011] In one embodiment, when supplying high power, the DC ends of all AC / DC rectification modules and the inputs of two DC / DC power supply modules in each group are connected in series to operate, so as to increase the system voltage and reduce the current; the outputs of two DC / DC power supply modules in each group are connected in parallel to output direct current.

[0012] In one embodiment, when supplying low power, the DC ends of each AC / DC rectification module and two DC / DC power supply modules in each group operate independently and output direct current to reduce the current.

[0013] In one embodiment, the AC / DC rectification module can discharge the AC grid, and the AC / DC rectification module is an AC-DC conversion circuit.

[0014] In one embodiment, the number of AC / DC rectification modules is two. The AC terminals of the two AC / DC rectification modules are connected to the AC power grid in parallel, and the DC terminals of the two AC / DC rectification modules are connected in series.

[0015] In one embodiment, an AC switch is provided on the line where each AC / DC rectification module is connected to the AC power grid.

[0016] In one embodiment, an AC switch protection circuit is further included, and the AC switch protection circuit is a circuit breaker or a fuse.

[0017] In one embodiment, two energy storage systems are further included. The two energy storage systems cooperate with the DC terminals of the corresponding two AC / DC rectification modules respectively, and each AC / DC rectification module controls the charging and discharging of the corresponding energy storage system respectively.

[0018] Specifically, the two AC / DC rectification modules are connected in parallel at AC and in series at DC, and can control the charging and discharging of the energy storage system respectively. The energy storage system is not essential and is an additional technical feature, which increases the function of electrical energy storage in the circuit. The AC / DC rectification module is an AC-DC conversion circuit, which can realize bidirectional control of electrical energy, that is, it can charge the energy storage system and discharge to the AC power grid, and has the functions of DC constant voltage, constant current, and constant power.

[0019] In one embodiment, the energy storage system is a battery system, and the battery system includes a battery storage unit and a battery management system.

[0020] Specifically, the battery system in this circuit structure is not essential. When there is no battery system, the AC / DC rectification module operates at a constant voltage. The series and parallel circuit structures of the AC / DC rectification module and the DC / DC power supply module, as well as the conversion logic of large and small power operations.

[0021] In one embodiment, a DC transmission cable is further included, and a switch group for output switching of the DC / DC power supply module is provided at the output end of each DC / DC power supply module.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. This circuit structure can perform low-voltage and high-voltage transmission switching. High-voltage transmission is adopted at high power, and low-voltage transmission is adopted at low power, which improves the high-power supply power and supply distance and improves the power supply efficiency. High-voltage transmission of low-voltage components can supply power at low voltage and low power at low power to improve the system efficiency.

[0024] 2. The input ends of two DC / DC power supply modules in the same group are connected in series, and the output ends are connected in parallel to form a DC output; an even number of DC / DC power supply modules realizes an even number of DC outputs.

[0025] 2. The number of AC / DC rectifier modules and DC / DC power supply modules can be increased or decreased according to this circuit structure, with high flexibility.

[0026] 3. DC / DC power supply module: A circuit that can perform step-up and step-down control of direct current and two-way control of electrical energy, with electrical isolation between input and output.

[0027] 4. The AC / DC rectifier module is an AC-DC conversion circuit. It can achieve two-way control of electrical energy, that is, it can charge the energy storage system and discharge to the AC grid, and has the functions of DC constant voltage, constant current, and constant power. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a schematic structural diagram of a long-distance DC power transmission circuit structure of the present invention. Detailed Embodiments

[0030] To make the technical problems, technical solutions, and technical effects of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0032] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, terms such as "first" and "second" are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0033] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "inner", "outer", "upper", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0034] Embodiment 1

[0035] As Figure 1 shown, this embodiment provides a long-distance DC power transmission circuit structure, including an AC switch, multiple AC / DC rectification modules at the grid end, a DC power transmission cable, and multiple DC / DC power supply modules at the remote end. The number of AC / DC rectification modules is M, and the number of DC / DC power supply modules is 2M. Two DC / DC power supply modules form a group and cooperate with the corresponding AC / DC rectification module. The AC terminals of all AC / DC rectification modules are connected to the AC grid at the grid end in parallel, and the DC terminals of each AC / DC rectification module are connected to a group of two corresponding DC / DC power supply modules. The inputs of the two DC / DC power supply modules in the same group are connected in series, and the outputs are connected in parallel to form a DC output; the 2M DC / DC power supply modules achieve M DC outputs.

[0036] Specifically, this circuit structure can perform low-voltage and high-voltage transmission switching. When the power is large, high-voltage power transmission is adopted, and when the power is small, low-voltage power transmission is adopted, which improves the high-power supply power and supply distance and increases the power supply efficiency. For high-voltage power transmission of low-voltage devices, when the power is small, low-voltage and low-power power supply can be used to improve the system efficiency.

[0037] The number of AC / DC rectification modules and DC / DC power supply modules can be increased or decreased according to this circuit structure, with high flexibility. DC / DC power supply module: A circuit that can perform step-up and step-down control of direct current and two-way control of electric energy, and has an electrical isolation function between the input and output.

[0038] Embodiment 2

[0039] As Figure 1As shown in the figure, this embodiment provides a long-distance DC power transmission circuit structure, including an AC switch, multiple AC / DC rectification modules at the grid end, a DC power transmission cable, and multiple DC / DC power supply modules at the remote end. The number of AC / DC rectification modules is M, and the number of DC / DC power supply modules is 2M. Two DC / DC power supply modules form a group and cooperate with the corresponding AC / DC rectification module. The AC terminals of all AC / DC rectification modules are connected to the AC grid at the grid end in parallel, and the DC terminals of each AC / DC rectification module are connected to a corresponding group of two DC / DC power supply modules. The inputs of the two DC / DC power supply modules in the same group are connected in series, and the outputs are connected in parallel to form a DC output; the 2M DC / DC power supply modules achieve M DC outputs.

[0040] When supplying high power, the DC terminals of all AC / DC rectification modules and the inputs of two DC / DC power supply modules in each group are connected in series to operate, so as to increase the system voltage and reduce the current; the outputs of two DC / DC power supply modules in each group are connected in parallel to output DC.

[0041] When supplying low power, the DC terminals of each AC / DC rectification module and two DC / DC power supply modules in each group operate independently to output DC, so as to reduce the current.

[0042] Embodiment 3

[0043] This embodiment is further optimized on the basis of Embodiment 2. Specifically:

[0044] The AC / DC rectification module can discharge to the AC grid, and the AC / DC rectification module is an AC-DC conversion circuit.

[0045] The number of AC / DC rectification modules is two. The AC terminals of the two AC / DC rectification modules are connected to the AC grid in parallel, and the DC terminals of the two AC / DC rectification modules are connected in series.

[0046] An AC switch is provided on the line where each AC / DC rectification module is connected to the AC grid.

[0047] Embodiment 4

[0048] This embodiment is further optimized on the basis of Embodiment 3. Specifically:

[0049] It also includes an AC switch protection circuit, and the AC switch protection circuit is a circuit breaker or a fuse.

[0050] It also includes two energy storage systems. The two energy storage systems respectively cooperate with the DC terminals of the corresponding two AC / DC rectification modules, and each AC / DC rectification module respectively controls the charging and discharging of the corresponding energy storage system.

[0051] Specifically, two AC / DC rectifier modules are connected in parallel on the AC side and in series on the DC side, which can respectively control the charge and discharge of the energy storage system. The energy storage system is non-essential and is an additional technical feature, adding the function of electrical energy storage to the circuit. The AC / DC rectifier module is an AC-DC conversion circuit, which can achieve bidirectional control of electrical energy, that is, it can charge the energy storage system and discharge to the AC power grid, and has the functions of DC constant voltage, constant current, and constant power.

[0052] Embodiment 5

[0053] This embodiment is further optimized on the basis of Embodiment 4. Specifically:

[0054] The energy storage system is a battery system, which includes a battery storage unit and a battery management system.

[0055] Specifically, this circuit structure does not necessarily require a battery system. When there is no battery system, the AC / DC rectifier module operates at a constant voltage. The series and parallel circuit structures of the AC / DC rectifier module and the DC / DC power supply module, as well as the conversion logic of large and small power operation.

[0056] It also includes a DC transmission cable, and a switch group for output switching of the DC / DC power supply module is provided at the output end of each DC / DC power supply module.

Claims

1. A long-distance direct current transmission circuit structure, characterized in that: It includes an AC switch, multiple AC / DC rectifier modules at the grid end, a DC transmission cable, and multiple DC / DC power supply modules at the remote end. The number of the AC / DC rectifier modules is M, the number of the DC / DC power supply modules is 2M, two DC / DC power supply modules form a group and cooperate with the corresponding AC / DC rectifier modules, the AC ends of all the AC / DC rectifier modules are connected to the AC grid at the grid end in parallel, and the DC end of each AC / DC rectifier module is connected to a corresponding group of two DC / DC power supply modules, the input ends of the two DC / DC power supply modules in the same group are connected in series, and the output ends are connected in parallel to form a DC output; 2M DC / DC power supply modules realize M DC outputs.

2. A long-distance direct current transmission circuit structure according to claim 1, characterized in that: When supplying high power, the DC ends of all the AC / DC rectifier modules and the input ends of each group of two DC / DC power supply modules are connected in series to increase the system voltage and reduce the current; the output ends of each group of two DC / DC power supply modules are connected in parallel to output DC.

3. A long-distance direct current transmission circuit structure according to claim 2, characterized in that: When the power is low, the DC end of each AC / DC rectifier module and each group of two DC / DC power supply modules operate independently and output DC to reduce the current.

4. A long-distance direct current transmission circuit structure according to claim 1, characterized in that: The AC / DC rectifier module can discharge the AC power grid, and the AC / DC rectifier module is an AC / DC conversion circuit.

5. The long-distance DC transmission circuit structure according to claim 1, characterized in that: The number of the AC / DC rectifier modules is two, the AC ends of the two AC / DC rectifier modules are connected to the AC power grid in parallel, and the DC ends of the two AC / DC rectifier modules are connected in series.

6. A long-distance direct current transmission circuit structure according to claim 5, characterized in that: An AC switch is provided on the line connecting each of the AC / DC rectifier modules and the AC power grid.

7. A long-distance direct current transmission circuit structure according to claim 6, characterized in that: It also includes an AC switch protection circuit, which is a circuit breaker or a fuse.

8. A long-distance direct current transmission circuit structure according to claim 5, characterized in that: It also includes two energy storage systems, which are respectively coordinated with the DC ends of the two corresponding AC / DC rectifier modules, and each AC / DC rectifier module respectively controls the charging and discharging of the corresponding energy storage system.

9. A long-distance direct current transmission circuit structure according to claim 8, characterized in that: The energy storage system is a battery system, which includes a battery storage unit and a battery management system.

10. A long-distance direct current transmission circuit structure according to claim 1, characterized in that: It also includes a direct current transmission cable, and the output end of each DC / DC power supply module is provided with a switch group for switching the output of the DC / DC power supply module.

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