Combiner box and photovoltaic system
By using an excitation fuse and a current and voltage sampling control system in the combiner box, the problems of slow circuit breaker action and arcing were solved, enabling rapid disconnection of fault current and ensuring the safety of the photovoltaic system.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SUNGROW POWER SUPPLY CO LTD
- Filing Date
- 2025-03-17
- Publication Date
- 2026-07-30
AI Technical Summary
Existing combiner box circuit breakers are slow to operate and prone to arcing, failing to disconnect fault current in time and causing the fault to escalate.
An excitation fuse is connected in series in the bus circuit. Faults are detected by current and voltage sampling circuits. The controller controls the excitation fuse to automatically or passively disconnect in the event of a fault, replacing the traditional circuit breaker.
It enables rapid disconnection of fault current, avoids arcing, promptly reduces the fault range, and protects the combiner box and system safety.
Smart Images
Figure CN2025082843_30072026_PF_FP_ABST
Abstract
Description
A combiner box and photovoltaic system
[0001] This application claims priority to Chinese Patent Application No. 202510113083.3, filed on January 23, 2025, entitled "A Combiner Box and Photovoltaic System", the entire contents of which are incorporated herein by reference. Technical Field
[0002] This application relates to the field of photovoltaic power generation technology, specifically to a combiner box and a photovoltaic system. Background Technology
[0003] Combiner boxes are commonly used in photovoltaic systems to combine the current from multiple photovoltaic panels and then connect it to the DC side of the inverter.
[0004] In related technologies, combiner boxes include switches, which are generally implemented using circuit breakers. When a fault occurs in the combiner box, the circuit breaker disconnects the combiner circuit, thereby interrupting the fault current. However, circuit breakers operate relatively slowly and can experience arcing during interruption. Summary of the Invention
[0005] In view of this, this application provides a combiner box and a photovoltaic system that can disconnect the combiner path in a timely manner when the combiner box needs to disconnect the combiner path, and the action is fast and does not produce arcing.
[0006] This application provides a combiner box, the combiner box comprising: a combiner circuit and an excitation fuse;
[0007] The excitation fuse is connected in series in the busbar circuit; the busbar circuit is used to combine current to multiple photovoltaic panels, and the excitation fuse is used to automatically melt or be controlled to disconnect when the current box experiences insulation failure or short circuit fault.
[0008] One possible implementation further includes: a current sampling circuit and a controller; the current sampling circuit is used to detect the current on the branch corresponding to the photovoltaic panel and send it to the controller;
[0009] The controller is used to determine that the combiner box has an insulation failure or short circuit fault when the current on the branch exceeds the current threshold, and to control the excitation fuse to open.
[0010] In one possible implementation, the controller is configured to control the excitation fuse to open when the current direction on the branch is from the photovoltaic panel to the combiner box and the current exceeds the current threshold.
[0011] In one possible implementation, the controller is configured to control the excitation fuse to disconnect when the current direction on the branch is from the combiner box to the photovoltaic panel and the current exceeds the current threshold.
[0012] One possible implementation further includes: a voltage sampling circuit; the voltage sampling circuit is used to acquire the output voltage of the combiner box and send it to the controller;
[0013] The controller is configured to control the excitation fuse to open when the output voltage is less than the voltage threshold and the current exceeds the current threshold.
[0014] One possible implementation is that the excitation fuse includes a first excitation fuse and / or a second excitation fuse, wherein the first excitation fuse is connected in series in the positive bus path of the combiner box, and the second excitation fuse is connected in series in the negative bus path of the combiner box.
[0015] One possible implementation further includes: N branches, each branch including a DC fuse; the N branches are connected together to the busbar, and the N branches are respectively connected to N photovoltaic panels, with each photovoltaic panel connected together through a corresponding DC fuse.
[0016] One possible implementation further includes: E direct current to direct current (DC-DC) conversion circuits, i.e., DC-DC conversion circuits; the input terminal of each DC-DC conversion circuit is used to connect N branches, each branch is connected to a corresponding photovoltaic panel; E is an integer greater than or equal to 1; the output terminals of the E DC-DC conversion circuits are connected in parallel to a busbar, and the busbar is connected to the busbar path.
[0017] One possible implementation further includes: E DC-DC converter circuits; the input terminal of each DC-DC converter circuit is used to connect N branches, and each branch is connected to a corresponding photovoltaic panel; E is an integer greater than or equal to 1; the output terminals of the E DC-DC converter circuits are connected to the first terminal of their respective excitation fuses, and the second terminals of all excitation fuses are connected in parallel.
[0018] In one possible implementation, the controller is configured to disconnect the excitation fuse connected to the DC-DC converter circuit when the current in the branch connected to the DC-DC converter circuit is greater than a current threshold, or when an insulation fault occurs in the DC-DC converter circuit.
[0019] This application also provides a photovoltaic system, including: an inverter and a combiner box as described above; the input terminal of the combiner box is used to connect to a corresponding photovoltaic panel, and the output terminal of the combiner box is used to connect to the DC side of the inverter.
[0020] One possible implementation is that there are multiple combiner boxes, and the output terminals of the multiple combiner boxes are connected to the DC side of the inverter.
[0021] The combiner box provided in this application embodiment has an excitation fuse connected in series in the combiner circuit. When the combiner box experiences insulation failure or a short circuit fault, the excitation fuse automatically blows or is passively disconnected. For example, it can automatically blow when the current flowing through the excitation fuse is large. Moreover, the excitation fuse is also a controllable device that can receive control signals and be passively disconnected. When the excitation fuse disconnects, it can cut off the fault current. The excitation fuse acts quickly and does not cause arcing, thus narrowing the fault range and providing timely protection. Attached Figure Description
[0022] Figure 1 is a schematic diagram of a photovoltaic system provided in an embodiment of this application;
[0023] Figure 2 is a diagram of the internal structure of a junction box;
[0024] Figure 3 is a schematic diagram of a junction box provided in an embodiment of this application;
[0025] Figure 4 is a schematic diagram of another junction box provided in an embodiment of this application;
[0026] Figure 5 is a schematic diagram of another type of combiner box provided in an embodiment of this application;
[0027] Figure 6 is a schematic diagram of another junction box provided in an embodiment of this application;
[0028] Figure 7 is a schematic diagram of another junction box provided in an embodiment of this application;
[0029] Figure 8 is a schematic diagram of another type of combiner box provided in an embodiment of this application;
[0030] Figure 9 is a schematic diagram of a photovoltaic system provided in an embodiment of this application. Detailed Implementation
[0031] To enable those skilled in the art to better understand and implement the combiner box provided in the embodiments of this application, the application scenarios of the combiner box will be introduced below with reference to the accompanying drawings.
[0032] Combiner boxes are used in photovoltaic (PV) systems. A PV system typically includes multiple combiner boxes, although theoretically it can also include only one. For ease of understanding, the following explanation uses a PV system with multiple combiner boxes as an example.
[0033] Referring to Figure 1, this figure is a schematic diagram of a photovoltaic system provided in an embodiment of this application.
[0034] The photovoltaic system provided in this application embodiment includes multiple combiner boxes, namely, the first combiner box 101 to the Mth combiner box 10m. The output terminals of the first combiner box 101 to the Mth combiner box 10m are connected to the DC side of the inverter 200. The main function of the combiner boxes is to combine current from multiple photovoltaic panels.
[0035] Each combiner box has multiple photovoltaic (PV) panels connected to its input. Figure 1 illustrates an example where each combiner box has n PV panels connected to its input, where n is an integer greater than or equal to 2. This means each combiner box connects to PV1 through PVn, a total of n PV panels. It should be understood that, generally, for ease of calculation and control, the number of PV panels connected to the inputs of multiple combiner boxes should be as similar as possible. This application does not specifically limit the number of PV panels connected to each combiner box. It should be understood that, in the case of multiple combiner boxes, the actual number of PV panels connected to each combiner box depends on the specific circumstances.
[0036] To facilitate understanding, the following section combines the internal architecture of a junction box from related technologies.
[0037] See Figure 2, which is a diagram of the internal architecture of a junction box.
[0038] Figure 2 illustrates a single combiner box. For simplicity, we'll use the case where the combiner box includes multiple branches and a single mains circuit as an example. Each branch can include a DC fuse. We'll describe the positive and negative branches separately. That is, the combiner box includes n positive branches, each with a DC fuse connected in series, designated Q1+ to Qn+. These n positive branches connect to the positive terminals PV1+ to PVn+ of the corresponding n photovoltaic panels. Similarly, the combiner box includes n negative branches, each with a DC fuse connected in series, designated Q1- to Qn-. These n negative branches connect to the negative terminals PV1- to PVn- of the corresponding n photovoltaic panels.
[0039] The combiner box includes a positive bus path and a negative bus path, with a switch K connected in series in both. Switch K is typically a circuit breaker. When the combiner box output is overloaded, the circuit breaker breaks the circuit, thus interrupting the fault current. However, circuit breakers operate relatively slowly. Before interrupting the fault current, the main components of the overload circuit overheat severely, insulation fails, and fuses cause the fault to escalate. A faulty circuit breaker tripping causes arcing, generating a large number of high-temperature metallic gas particles. This reduces the electrical clearance within the enclosed space of the combiner box, easily leading to arcing between the positive and negative high-voltage circuits, resulting in severe combiner box failure.
[0040] In order to disconnect the bus circuit in a timely manner when the bus circuit needs to be disconnected, and to act quickly without arcing, the junction box provided in this application uses an excitation fuse instead of the switch K in Figure 2, that is, instead of the circuit breaker.
[0041] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods.
[0042] Referring to Figure 3, this figure is a schematic diagram of a combiner box provided in an embodiment of this application.
[0043] The combiner box 100 provided in this application embodiment includes: an excitation fuse and a combiner circuit.
[0044] An excitation fuse is connected in series in the busbar path; the busbar path is used to combine current to multiple photovoltaic panels; the combiner box includes a positive busbar path DC+ and a negative busbar path DC-. The combiner box 100 provided in this embodiment may include a first excitation fuse F1 and / or a second excitation fuse F2. Figure 3 illustrates an embodiment of this application where the positive busbar path DC+ and the negative busbar path DC- are connected in series with the first excitation fuse F1 and the second excitation fuse F2, respectively. It should be understood that the first excitation fuse F1 may be connected in series only in the positive busbar path, or the second excitation fuse F2 may be connected in series only in the negative busbar path. Both the positive busbar path DC+ and the negative busbar path DC- are connected to the DC side of the inverter 200.
[0045] The combiner box includes n positive branches, each with a DC fuse connected in series, numbered Q1+ to Qn+. Similarly, the combiner box includes n negative branches, each with a DC fuse connected in series, numbered Q1- to Qn-.
[0046] The excitation fuse is used to automatically blow or be controlled to disconnect when an insulation failure or short circuit fault occurs in the combiner box. For example, when the excitation fuse includes a first excitation fuse F1 and a second excitation fuse F2, the controller needs to control both the first excitation fuse F1 and the second excitation fuse F2 to disconnect.
[0047] The excitation fuse operates relatively quickly, and can generally complete the protection action in a very short time.
[0048] Insulation failure occurs in the combiner box, such as an insulation fault between the excitation fuse and the photovoltaic panel, or an insulation fault between the excitation fuse and the inverter.
[0049] The combiner box provided in this application embodiment has an excitation fuse connected in series in the combiner circuit. Since the excitation fuse controller can actively control the excitation fuse to disconnect, cut off the fault current, the excitation fuse acts quickly and will not cause arcing, thus reducing the fault range and providing timely protection.
[0050] The combiner box provided in this embodiment may also include multiple DC fuses, as shown in Figure 4. Compared to Figure 3, Figure 4 adds DC fuses. The combiner box also includes: N branches, each branch including one DC fuse; the N branches are combined together to connect to the busbar path; the N branches are respectively connected to N photovoltaic panels, and each photovoltaic panel is combined together through a corresponding DC fuse. The DC fuses are connected to the branches, and the excitation fuses are connected to the busbar path. The combiner box includes n positive branches, each positive branch with a DC fuse connected in series, namely Q1+ to Qn+. Similarly, the combiner box includes n negative branches, each negative branch with a DC fuse connected in series, namely Q1- to Qn-.
[0051] The following diagram illustrates how to determine when insulation failure occurs in a combiner box. When insulation failure occurs, a relatively large current will be generated. Therefore, insulation failure can be determined by detecting the current.
[0052] See Figure 5, which is a schematic diagram of another type of combiner box provided in an embodiment of this application.
[0053] The combiner box provided in this application embodiment also includes: a current sampling circuit 102 and a controller 101.
[0054] The current sampling circuit 102 is used to detect the current on the branch corresponding to the photovoltaic panel and send it to the controller 101;
[0055] Controller 101 is used to determine if an insulation failure or short-circuit fault has occurred in the combiner box when the current on a branch exceeds a current threshold, and to control the excitation fuse to open. It should be understood that in the case of multiple branches, if the current on any one branch exceeds the current threshold, it indicates an insulation failure or short-circuit fault. When the excitation fuses include a first excitation fuse F1 and a second excitation fuse F2, the controller needs to control both the first excitation fuse F1 and the second excitation fuse F2 to open.
[0056] This application does not specifically limit the direction of the current when it exceeds a current threshold; it can be either forward or reverse. Forward flow refers to the current flowing from the photovoltaic panel to the combiner box, i.e., from the branch circuit to the excitation fuse. In one possible scenario, the controller is used to control the excitation fuse to open when the current in the branch circuit flows from the photovoltaic panel to the combiner box and exceeds a current threshold.
[0057] The reverse direction is from the combiner box to the photovoltaic panel, that is, from the excitation fuse to the branch. In one possible scenario, the controller is used to control the excitation fuse to open when the current direction in the branch is from the combiner box to the photovoltaic panel and the current exceeds the current threshold.
[0058] In order to better determine whether the junction box has insulation failure or short circuit fault, the current detection result can be combined with the voltage detection result to make a judgment in addition to the current detection result.
[0059] Referring to Figure 6, this figure is a schematic diagram of another combiner box provided in an embodiment of this application.
[0060] The combiner box provided in this application embodiment includes a controller 101 and a current sampling circuit 102, as well as a voltage sampling circuit 103.
[0061] The voltage sampling circuit 103 is used to collect the output voltage of the combiner box and send it to the controller 101.
[0062] Controller 101 is used to control the excitation fuse to open when the output voltage is less than a voltage threshold and the current exceeds a current threshold. When the excitation fuse includes a first excitation fuse F1 and a second excitation fuse F2, the controller needs to control both the first excitation fuse F1 and the second excitation fuse F2 to open.
[0063] It should be understood that when a combiner box experiences insulation failure or a short circuit fault, in addition to an increase in branch current, the output voltage of the combiner circuit will also decrease. Therefore, the output voltage can be used to determine whether the combiner box has experienced insulation failure or a short circuit fault.
[0064] In addition, the combiner box provided in this application embodiment may also include a DC-DC conversion circuit, which will be described in detail below with reference to the accompanying drawings.
[0065] See Figure 7, which is a schematic diagram of another junction box provided in an embodiment of this application.
[0066] The combiner box provided in this application embodiment further includes: E DC-DC conversion circuits; the input terminal of each DC-DC conversion circuit is used to connect to N branches, and each branch is connected to a corresponding photovoltaic panel. E is an integer greater than or equal to 1. The combiner box provided in this application embodiment includes an excitation fuse on each branch where the DC-DC conversion circuit is located.
[0067] It should be understood that each DC-DC converter circuit can correspond to either only the first excitation fuse F1 or only the second excitation fuse F2. The following example uses one DC-DC converter circuit with two excitation fuses. The output terminals of the E DC-DC converter circuits are connected to the first terminals of their respective excitation fuses, and the second terminals of all excitation fuses are connected in parallel. That is, each DC-DC converter circuit corresponds to one first excitation fuse F1 and one second excitation fuse F2. The positive output terminal of each DC-DC converter circuit is connected to the first terminal of its corresponding first excitation fuse, and the negative output terminal of each DC-DC converter circuit is connected to the first terminal of its corresponding second excitation fuse. The second terminals of all first excitation fuses are connected together, and the second terminals of all second excitation fuses are connected together.
[0068] The controller is used to disconnect the excitation fuse connected to the DC-DC converter circuit when the current in the branch connected to the DC-DC converter circuit exceeds the current threshold, or when an insulation fault occurs in the DC-DC converter circuit.
[0069] The combiner box provided in this embodiment has the same acquisition positions for the current detection circuit and voltage sampling circuit as in Figure 6, and will not be repeated here. It should be understood that the current detection circuit needs to acquire the current of each branch. The figure only illustrates the current of one branch connected to a DC-DC converter circuit.
[0070] Figure 7 shows that an excitation fuse is installed on the branch corresponding to each DC-DC converter circuit. In the event of insulation failure or insulation fault, only the excitation fuse associated with the fault is controlled to open, while the branch without fault can continue to work. This does not affect the power generation of other normal branches, and the subsequent inverter can continue to operate.
[0071] The following description, in conjunction with the accompanying drawings, illustrates the implementation of a combiner box that may also include a DC-DC converter circuit, according to embodiments of this application.
[0072] See Figure 8, which is a schematic diagram of another type of combiner box provided in an embodiment of this application.
[0073] The combiner box provided in this embodiment further includes: E DC-DC converter circuits; the input terminal of each DC-DC converter circuit is used to connect N branches, and each branch is connected to a corresponding photovoltaic panel. E is an integer greater than or equal to 1. The output terminals of the E DC-DC converter circuits are connected in parallel to the combiner point, and the combiner point is connected to the combiner path.
[0074] The combiner box provided in this application embodiment includes excitation fuses on the trunk line after all DC-DC combiners. Comparing Figure 7 and Figure 8, it can be seen that Figure 8 can save the number of excitation fuses.
[0075] The combiner box provided in this embodiment has the same acquisition positions for the current detection circuit and voltage sampling circuit as in Figure 6, and will not be repeated here. It should be understood that the current detection circuit needs to acquire the current of each branch. The figure only illustrates the current of one branch connected to a DC-DC converter circuit.
[0076] The combiner box provided in this application embodiment, when including a DC-DC conversion circuit, can also be set with an excitation fuse to actively control the excitation fuse to disconnect when an insulation failure or short circuit fault occurs. This can quickly complete the protection action without arcing.
[0077] Based on the combiner box provided in the above embodiments, this application also provides a photovoltaic system, which will be described in detail below with reference to the accompanying drawings.
[0078] See Figure 9, which is a schematic diagram of a photovoltaic system provided in an embodiment of this application.
[0079] The photovoltaic system provided in this application includes: an inverter 200 and any of the combiner boxes 100 described in the above embodiments.
[0080] The input terminal of combiner box 100 is used to connect to the corresponding photovoltaic panels, for example, to connect N photovoltaic panels, namely PV1-PVn. The output terminal of the combiner box is used to connect to the DC side of inverter 200.
[0081] It should be understood that a photovoltaic system may include multiple combiner boxes, and the output terminals of multiple combiner boxes are connected to the DC side of the inverter, as shown in Figure 1.
[0082] Since the combiner box in the photovoltaic system provided in this application includes an excitation fuse, when the combiner box experiences insulation failure or a short circuit fault, the excitation fuse is controlled to disconnect the combiner circuit, thereby disconnecting the combiner circuit from the downstream inverter, preventing the fault from continuing to the inverter, and promptly reducing the scope of the fault.
[0083] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0084] The above description of the disclosed embodiments enables those skilled in the art to make 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 may 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 busbar characterized by, The junction box includes: a junction path and an excitation fuse; The excitation fuse is connected in series in the busbar circuit; the busbar circuit is used to combine current to multiple photovoltaic panels, and the excitation fuse is used to automatically melt or be controlled to disconnect when the current box experiences insulation failure or short circuit fault.
2. The collection box of claim 1, wherein, Also includes: Current sampling circuit and controller; The current sampling circuit is used to detect the current on the branch corresponding to the photovoltaic panel and send it to the controller; The controller is used to determine that the combiner box has an insulation failure or short circuit fault when the current on the branch exceeds the current threshold, and to control the excitation fuse to open.
3. The combiner box according to claim 2, characterized in that, The controller is configured to control the excitation fuse to open when the current direction on the branch is from the photovoltaic panel to the combiner box, and the current exceeds the current threshold.
4. The combiner box according to claim 2, characterized in that, The controller is configured to control the excitation fuse to disconnect when the current direction on the branch is from the combiner box to the photovoltaic panel and the current exceeds the current threshold.
5. The combiner box according to claim 2, characterized in that, Also includes: Voltage sampling circuit; The voltage sampling circuit is used to collect the output voltage of the combiner box and send it to the controller; The controller is configured to control the excitation fuse to open when the output voltage is less than the voltage threshold and the current exceeds the current threshold.
6. The combiner box according to any one of claims 1-5, characterized in that, The excitation fuse includes a first excitation fuse and / or a second excitation fuse, wherein the first excitation fuse is connected in series in the positive bus path of the combiner box, and the second excitation fuse is connected in series in the negative bus path of the combiner box.
7. The combiner box according to any one of claims 1-5, characterized in that, Also includes: There are N branches, each branch includes a DC fuse; The N branches are connected together to form the main flow path, and each of the N branches is connected to N photovoltaic panels. Each photovoltaic panel is connected together through a corresponding DC fuse.
8. The combiner box according to any one of claims 1-5, characterized in that, It also includes: E DC-DC converter circuits; the input terminal of each DC-DC converter circuit is used to connect to N branches, and each branch is connected to the corresponding photovoltaic panel; E is an integer greater than or equal to 1; The outputs of the E DC-DC converter circuits are connected in parallel to a busbar, and the busbar is connected to the busbar path.
9. The combiner box according to any one of claims 1-5, characterized in that, It also includes: E DC-DC converter circuits; the input terminal of each DC-DC converter circuit is used to connect to N branches, and each branch is connected to the corresponding photovoltaic panel; E is an integer greater than or equal to 1; The output terminals of each of the E DC-DC converter circuits are connected to the first terminal of their respective excitation fuses, and the second terminals of all the excitation fuses are connected in parallel.
10. The combiner box according to claim 8 or 9, characterized in that, The controller is configured to disconnect the excitation fuse connected to the DC-DC converter circuit when the current in the branch connected to the DC-DC converter circuit is greater than a current threshold, or when an insulation fault occurs in the DC-DC converter circuit.
11. A photovoltaic system, characterized in that, include: Inverter and combiner box as described in any one of claims 1-10; The input terminal of the combiner box is used to connect to the corresponding photovoltaic panel, and the output terminal of the combiner box is used to connect to the DC side of the inverter.
12. The photovoltaic system according to claim 11, characterized in that, There are multiple combiner boxes, and the output terminals of the multiple combiner boxes are connected to the DC side of the inverter.