Direct-current energy router, energy storage system and photovoltaic system

Abstract

The embodiment of the invention discloses a direct-current energy router, an energy storage system and a photovoltaic system. The direct-current energy router comprises a plurality of converters and a plurality of external equipment connecting ports, each converter is connected in series with one plug-in equipment connecting port, a series circuit of each converter and the plug-in equipment connecting port is mounted on the direct-current bus, and the converters are used for adjusting the power of the plug-in equipment connected with the plug-in equipment connecting ports. According to the direct-current energy router provided by the scheme, the series circuit of each converter and the connection port of the external equipment is mounted on the direct-current bus, so that the problem of imbalance among a plurality of external equipment mounted on the direct-current bus is solved, and meanwhile, the manufacturing cost of the direct-current energy router can be greatly reduced; and the power conversion loss of the direct-current energy router is greatly reduced.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of DC mounting technology, and in particular to a DC energy router, an energy storage system, and a photovoltaic system. Background Art

[0002] With the increasing number of DC buses, and the installation of different power sources or loads on these buses, it's necessary to control the direction and amount of power flowing to each power source or load to prevent imbalances between loads or power sources. For example, in centralized energy storage systems, to reduce costs, multiple battery clusters share a single AC converter. However, different battery clusters have different electrical characteristics. If these clusters are directly connected to the DC bus, imbalances between them can cause overcurrent in some clusters, potentially leading to safety issues.

[0003] Currently, to address the imbalance between power supplies or loads directly connected to the DC bus, a bidirectional DC-DC converter is typically added to each power supply or load port. However, the power capacity of each bidirectional DC-DC converter cannot be less than the maximum power of the corresponding power supply or load. Obviously, the high power capacity required of bidirectional DC-DC converters increases the cost of the entire system. Furthermore, each bidirectional DC-DC converter has a conversion efficiency during operation, so if all power passes through the bidirectional DC-DC converter, it will increase operating losses. Summary of the Invention

[0004] Embodiments of the present invention provide a DC energy router, an energy storage system, and a photovoltaic system to reduce the cost and loss of solving the imbalance problem between multiple external devices mounted on a DC bus.

[0005] In a first aspect, an embodiment of the present invention provides a DC energy router, the DC energy router comprising a plurality of converters and a plurality of external device connection ports;

[0006] Each of the converters is connected in series with one of the external device connection ports. The series circuit of each converter and the external device connection port is mounted on a DC bus. The converter is used to adjust the power of the external device connected to the external device connection port.

[0007] Optionally, the converter includes a DC-DC converter;

[0008] The first end of the DC-DC converter is connected to one pole of the DC bus, the second end of the DC-DC converter is connected to the first end of the external device connection port, and the second end of the external device connection port is connected to the other pole of the DC bus.

[0009] Optionally, the third terminals of all the DC-DC converters are interconnected, and the fourth terminals of all the DC-DC converters are interconnected.

[0010] Optionally, the third terminal of each DC-DC converter is connected to one pole of the DC bus, and the fourth terminal of each DC-DC converter is connected to the other pole of the DC bus.

[0011] Optionally, the DC energy router further includes an auxiliary DC power supply;

[0012] The third terminal of each DC-DC converter is connected to one pole of the auxiliary DC power supply, and the fourth terminal of each DC-DC converter is connected to the other pole of the auxiliary DC power supply.

[0013] Optionally, the DC energy router further includes a first inverter and a first auxiliary AC power supply;

[0014] The third end of each DC-DC converter is connected to the first end of the first inverter, the fourth end of each DC-DC converter is connected to the second end of the first inverter, the third end of the first inverter is connected to one pole of the first auxiliary AC power supply, and the fourth end of the first inverter is connected to the other pole of the first auxiliary AC power supply.

[0015] Optionally, the DC energy router further includes a second auxiliary AC power supply;

[0016] The converter includes a second inverter;

[0017] A first end of the second inverter is connected to one pole of the DC bus, a second end of the second inverter is connected to a first end of the external device connection port, and a second end of the external device connection port is connected to the other pole of the DC bus;

[0018] The third terminal of the second inverter is connected to one pole of the second auxiliary AC power supply, and the fourth terminal of the second inverter is connected to the other pole of the second auxiliary AC power supply.

[0019] Optionally, the DC energy router further includes a converter;

[0020] The converter is connected to the DC bus.

[0021] In a second aspect, an embodiment of the present invention further provides an energy storage system, which includes a plurality of energy storage batteries and a DC energy router provided by any embodiment of the present invention;

[0022] Each of the energy storage batteries is connected to one of the external device connection ports.

[0023] In a third aspect, an embodiment of the present invention further provides a photovoltaic system, which includes a plurality of photovoltaic strings and a DC energy router provided by an embodiment of the present invention;

[0024] Each of the photovoltaic strings is connected to one of the external device connection ports.

[0025] By mounting the series circuit connecting each converter and the external device connection port on the DC bus, this embodiment of the present invention ensures that only a small portion of the power flow from the external devices connected to the DC bus flows through the converter, thereby reducing the power capacity requirements of the converter and lowering the converter's power conversion losses. Thus, the DC energy router provided by this solution, by mounting the series circuit connecting each converter and the external device connection port on the DC bus, not only solves the problem of imbalance between multiple external devices connected to the DC bus, but also significantly reduces the manufacturing cost of the DC energy router and significantly reduces the power conversion losses of the DC energy router. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 A schematic diagram of the structure of a DC energy router provided by the prior art;

[0028] Figure 2 A schematic diagram of the structure of a DC energy router provided in an embodiment of the present invention;

[0029] Figure 3 A schematic diagram of the structure of another DC energy router provided in an embodiment of the present invention;

[0030] Figure 4 A schematic diagram of the structure of another DC energy router provided in an embodiment of the present invention;

[0031] Figure 5 A schematic diagram of the structure of another DC energy router provided in an embodiment of the present invention;

[0032] Figure 6 A schematic diagram of the structure of another DC energy router provided in an embodiment of the present invention;

[0033] Figure 7 A schematic diagram of the structure of another DC energy router provided in an embodiment of the present invention;

[0034] Figure 8A schematic diagram of the structure of another DC energy router provided in an embodiment of the present invention;

[0035] Figure 9 A schematic structural diagram of an energy storage system provided in an embodiment of the present invention;

[0036] Figure 10 A schematic structural diagram of a photovoltaic system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0039] In order to better explain the solution of the present invention, the structure of the existing DC energy router is first briefly described.

[0040] Figure 1 A schematic diagram of the structure of a DC energy router provided by the prior art, such as Figure 1 As shown, the DC energy router includes a plurality of bidirectional DC-DC converters 10 , and each external device 20 is connected to the DC bus via a bidirectional DC-DC converter 10 .

[0041] The power capacity of each bidirectional DC-DC converter 10 must be greater than the maximum power of the corresponding external device 20, which significantly increases the manufacturing cost of the DC energy router. Furthermore, the bidirectional DC-DC converters 10 have a certain conversion efficiency, and all power from the DC bus must pass through the bidirectional DC-DC converters 10 before flowing to the external device 20, which increases losses in the overall operating system.

[0042] In response to the technical problems of high cost and large loss in the above-mentioned DC energy router, an embodiment of the present invention provides a DC energy router to reduce the cost and loss of solving the imbalance problem between multiple external devices 20 mounted on the DC bus.

[0043] Figure 2 A schematic diagram of the structure of a DC energy router provided by an embodiment of the present invention is shown as follows: Figure 2 As shown, the DC energy router includes a plurality of converters 110 and a plurality of external device connection ports 120;

[0044] Each converter 110 is connected in series with an external device connection port 120 . The series circuit of each converter 110 and external device connection port 120 is mounted on a DC bus DC (DC+ and DC-). The converter 110 is used to adjust the power of the external device connected to the external device connection port 120 .

[0045] The external device connection port 120 is a port for connecting an external device, allowing the series circuit of the converter 110 and the external device to be connected to the DC bus DC. Specifically, one end of the series circuit of the converter 110 and the external device is connected to the positive DC bus terminal DC+, and the other end of the series circuit of the converter 110 and the external device is connected to the negative DC bus terminal DC-. Converter 110 can indirectly control the power level of the external device connected through the external device connection port 120 by adjusting its own power flow direction, port voltage, or current, thereby eliminating voltage, current, or power imbalances between external devices with different characteristics.

[0046] Specifically, the series circuit of each converter 110 and external device connection port 120 is mounted on the DC bus DC (the DC bus positive pole DC+ and the DC bus negative pole DC-). This allows only a small portion of the power flow of the external device mounted on the DC bus DC to flow through the converter 110. This allows the converter 110, with its smaller power capacity, to adjust the power of the external device connected to the external device connection port 120. This significantly reduces the power capacity of the converter 110 required to adjust the power of the external device connected to the external device connection port 120, significantly reducing the manufacturing cost of the DC energy router. Furthermore, the reduced power flowing through the converter 110 significantly reduces the power conversion losses of the converter 110, significantly reducing the power conversion losses of the converter 110 when operating the DC energy router.

[0047] For example, if the external device is a storage battery, the current of the storage battery is 100A, the voltage of the storage battery is 990V, and the voltage of the DC bus is 1000V. Figure 1In the DC energy router, the power of the bidirectional DC-DC converter 10 is at least: 100A*990V=99KW; if the DC energy router provided by this embodiment is used, the voltage provided by the converter 110 is: 1000V-990V=100V, and the power of the converter 110 is at least: 100A*(1000-990)V=1KW. By comparison, it can be seen that Figure 1 The power capacity of the bidirectional DC-DC converter 10 used in this embodiment is much greater than that of the converter 110 in this embodiment. Therefore, the DC energy router provided by this embodiment can significantly reduce the cost and loss of solving the imbalance problem between multiple external devices connected to the DC bus.

[0048] This embodiment of the present invention mounts the series circuit connecting each converter 110 and the external device connection port 120 on the DC bus DC. This ensures that only a small portion of the power flow from the external devices connected to the DC bus DC flows through the converter 110, thereby reducing the power capacity requirement of the converter 110 and lowering the power conversion losses of the converter 110. Thus, the DC energy router provided by this solution, by mounting the series circuit connecting each converter 110 and the external device connection port 120 on the DC bus DC, not only solves the problem of imbalance between multiple external devices connected to the DC bus DC, but also significantly reduces the manufacturing cost of the DC energy router and significantly reduces the power conversion losses of the DC energy router.

[0049] Based on the above embodiment, optionally, Figure 3 A schematic diagram of the structure of another DC energy router provided by an embodiment of the present invention is shown as follows: Figure 3 As shown, the converter 110 includes a DC-DC converter 111;

[0050] A first end of the DC-DC converter 111 is connected to one pole of the DC bus DC, a second end of the DC-DC converter 111 is connected to a first end of the external device connection port 120, and a second end of the external device connection port 120 is connected to the other pole of the DC bus DC.

[0051] The DC-DC converter 111 may be connected to the positive pole DC+ of the DC bus, or may be connected to the negative pole DC- of the DC bus. Figure 3 In the embodiment, the DC-DC converter 111 is connected to the DC bus positive pole DC+, that is, the first end of the DC-DC converter 111 is connected to the DC bus positive pole DC+, and the second end of the external device connection port 120 is connected to the DC bus negative pole DC-.

[0052] In addition, the port on the other side of each DC-DC converter 111 that is not connected to the external device connection port 120 includes a third terminal and a fourth terminal. During operation of the DC energy router, each DC-DC converter 111 adjusts the power of the external device connected to the external device connection port 120 by adjusting its own power flow direction, port voltage, or current. The third and fourth terminals of the DC-DC converter 111 can be connected in the following ways. The various connection methods for the third and fourth terminals of the DC-DC converter 111 are described below.

[0053] On the basis of the above embodiment, optionally, continue to refer to Figure 3 , the third terminals of all DC-DC converters 111 are interconnected, and the fourth terminals of all DC-DC converters 111 are interconnected.

[0054] The third terminals of all DC-DC converters 111 are interconnected, and the fourth terminals of all DC-DC converters 111 are interconnected. This requires coordination between the DC-DC converters 111, specifically controlling the total power flow between all DC-DC converters 111 to zero, thereby adjusting the power of the external device connected to the external device connection port 120. This approach eliminates the need to feed power back to the DC bus, resulting in lower costs.

[0055] For example, it is assumed that the DC energy router includes three DC-DC converters 111, the absorption power of the third and fourth ends of the first DC-DC converter 111 is 0.5KW, the discharge power of the third and fourth ends of the second DC-DC converter 111 is 0.3KW, and the discharge power of the third and fourth ends of the third DC-DC converter 111 is 0.2KW.

[0056] Based on the above embodiment, optionally, Figure 4 A schematic diagram of the structure of another DC energy router provided by an embodiment of the present invention is shown as follows: Figure 4 As shown, the third terminal of each DC-DC converter 111 is connected to one pole of the DC bus DC, and the fourth terminal of each DC-DC converter 111 is connected to the other pole of the DC bus DC.

[0057] The third terminal and the fourth terminal of each DC-DC converter 111 are connected to the positive DC bus DC+ and the negative DC bus DC-, respectively. This method allows each DC-DC converter 111 to independently adjust the power of the external device connected to the external device connection port 120, thereby making the control of each DC-DC converter 111 simpler.

[0058] Based on the above embodiment, optionally, Figure 5 A schematic diagram of the structure of another DC energy router provided by an embodiment of the present invention is shown as follows: Figure 5 As shown, the DC energy router further includes an auxiliary DC power supply 30;

[0059] A third terminal of each DC-DC converter 111 is connected to one terminal of the auxiliary DC power supply 30 , and a fourth terminal of each DC-DC converter 111 is connected to the other terminal of the auxiliary DC power supply 30 .

[0060] The auxiliary DC power supply 30 can provide power to the DC-DC converter 111 or absorb power output from the DC-DC converter 111. Specifically, the auxiliary DC power supply 30 discharges power to the DC-DC converter 111 when it needs it, and the auxiliary DC power supply 30 stores power output from the DC-DC converter 111 through charging, thereby assisting the DC-DC converter 111 in adjusting the power of the external device connected to the external device connection port 120. This approach is cost-effective and simplifies the control of each DC-DC converter 111.

[0061] Based on the above embodiment, optionally, Figure 6 A schematic diagram of the structure of another DC energy router provided by an embodiment of the present invention is shown as follows: Figure 6 As shown, the DC energy router further includes a first inverter 40 and a first auxiliary AC power source 50;

[0062] The third end of each DC-DC converter 111 is connected to the first end of the first inverter 40, the fourth end of each DC-DC converter 111 is connected to the second end of the first inverter 40, the third end of the first inverter 40 is connected to one terminal of the first auxiliary AC power source 50, and the fourth end of the first inverter 40 is connected to the other terminal of the first auxiliary AC power source 50.

[0063] The first auxiliary AC power source 50 can output or store AC power. The first inverter 40 can convert the AC power output by the first auxiliary AC power source 50 into DC power and provide it to the DC-DC converter 111 that needs power, or convert the DC power output by the DC-DC converter 111 into AC power and store it in the first auxiliary AC power source 50. This approach is cost-effective and simplifies the control of each DC-DC converter 111.

[0064] Based on the above embodiment, optionally, Figure 7 A schematic diagram of the structure of another DC energy router provided by an embodiment of the present invention is shown as follows: Figure 7 As shown, the DC energy router further includes a second auxiliary AC power source 60; the converter 110 includes a second inverter 112;

[0065] A first end of the second inverter 112 is connected to one pole of the DC bus DC, a second end of the second inverter 112 is connected to a first end of the external device connection port 120, and a second end of the external device connection port 120 is connected to the other pole of the DC bus DC; a third end of the second inverter 112 is connected to one pole of the second auxiliary AC power supply 60, and a fourth end of the second inverter 112 is connected to the other pole of the second auxiliary AC power supply 60.

[0066] The second auxiliary AC power source 60 can output or store AC power. The second inverter 112 can convert DC power into AC power and store it in the second auxiliary AC power source 60 as needed. Alternatively, the second inverter 112 can convert AC power received from the second auxiliary AC power source 60 into DC power as needed. This approach is cost-effective and simplifies the control of each DC-DC converter 111.

[0067] Based on the above embodiment, optionally, Figure 8 A schematic diagram of the structure of another DC energy router provided by an embodiment of the present invention is shown as follows: Figure 8 As shown, the DC energy router further includes a converter 70 ; the converter 70 is connected to the DC bus DC.

[0068] The two ends of the converter 70 are connected to the DC bus's positive terminal (DC+) and negative terminal (DC-), respectively. The converter 70 can transmit externally input AC or DC power to the DC bus (DC) to power external devices attached to the DC bus (DC). The converter 70 can also convert DC power provided by external devices attached to the DC bus (DC) into DC or AC power to power external devices.

[0069] Figure 9 This is a schematic diagram of the structure of an energy storage system provided by an embodiment of the present invention. The energy storage system includes multiple energy storage batteries 200 and a DC energy router provided by any embodiment of the present invention. Each energy storage battery 200 is connected to an external device connection port 120. Furthermore, an energy storage system including a DC energy router provided by any embodiment of the present invention has the beneficial effects of the DC energy router provided by any embodiment of the present invention, which will not be further described here.

[0070] Figure 10 This is a schematic diagram of the structure of a photovoltaic system according to an embodiment of the present invention. The photovoltaic system includes multiple photovoltaic strings 300 and a DC energy router according to any embodiment of the present invention. Each photovoltaic string 300 is connected to an external device connection port 120. Furthermore, a photovoltaic system including a DC energy router according to any embodiment of the present invention has the beneficial effects of the DC energy router according to any embodiment of the present invention, which will not be further described here.

[0071] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. This is not limited herein.

[0072] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A DC energy router, characterized in that: Includes multiple converters and multiple external device connection ports; Each of the converters is connected in series with one of the external device connection ports. The series circuit of each converter and the external device connection port is mounted on a DC bus. The converter is used to adjust the power of the external device connected to the external device connection port.

2. The DC energy router according to claim 1, characterized in that: The converter includes a DC-DC converter; The first end of the DC-DC converter is connected to one pole of the DC bus, the second end of the DC-DC converter is connected to the first end of the external device connection port, and the second end of the external device connection port is connected to the other pole of the DC bus.

3. The DC energy router according to claim 2, characterized in that: The third terminals of all the DC-DC converters are interconnected, and the fourth terminals of all the DC-DC converters are interconnected.

4. The DC energy router according to claim 2, characterized in that: The third terminal of each DC-DC converter is connected to one pole of the DC bus, and the fourth terminal of each DC-DC converter is connected to the other pole of the DC bus.

5. The DC energy router according to claim 2, characterized in that: Also included is an auxiliary DC power supply; The third terminal of each DC-DC converter is connected to one pole of the auxiliary DC power supply, and the fourth terminal of each DC-DC converter is connected to the other pole of the auxiliary DC power supply.

6. The DC energy router according to claim 2, characterized in that: Also includes a first inverter and a first auxiliary AC power source; The third end of each DC-DC converter is connected to the first end of the first inverter, the fourth end of each DC-DC converter is connected to the second end of the first inverter, the third end of the first inverter is connected to one pole of the first auxiliary AC power supply, and the fourth end of the first inverter is connected to the other pole of the first auxiliary AC power supply.

7. The DC energy router according to claim 1, characterized in that: Also included is a second auxiliary AC power source; The converter includes a second inverter; A first end of the second inverter is connected to one pole of the DC bus, a second end of the second inverter is connected to a first end of the external device connection port, and a second end of the external device connection port is connected to the other pole of the DC bus; The third terminal of the second inverter is connected to one pole of the second auxiliary AC power supply, and the fourth terminal of the second inverter is connected to the other pole of the second auxiliary AC power supply.

8. The DC energy router according to any one of claims 1 to 7, characterized in that: Also includes a converter; The converter is connected to the DC bus.

9. An energy storage system, characterized in that: Comprising a plurality of energy storage batteries and a DC energy router according to any one of claims 1 to 8; Each of the energy storage batteries is connected to one of the external device connection ports.

10. A photovoltaic system, characterized in that: Comprising a plurality of photovoltaic strings and a DC energy router according to any one of claims 1 to 8; Each of the photovoltaic strings is connected to one of the external device connection ports.

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