Photovoltaic module MC4 joint wire pressing process

Abstract

The invention relates to the technical field of photovoltaic power generation equipment wiring technology, and discloses a photovoltaic module MC4 joint wire pressing process, which comprises a wire pressing terminal and a direct current cable, and comprises the following steps: adopting a two-stage winding process including a first-stage winding process and a second-stage winding process; the primary winding process comprises the following steps: separating out part of copper wires in the direct-current cable, and winding the copper wires outside the direct-current cable to form a primary winding body; the second-stage winding process comprises the steps that part of copper wires in the remaining copper wires in the direct-current cable are separated out and wound outside the first winding body to form a second-stage winding body, and the outer diameter of the second-stage winding body is larger than the outer diameter of the wire pressing terminal; the first-stage winding body and the second-stage winding body are inserted into the wire pressing terminal, and after the second-stage winding body is clamped at the notch position of the wire pressing terminal, the wire pressing terminal and the first-stage winding body are connected in a pressing mode through a corresponding tool; the method has the advantages of ensuring the electrical performance of the direct-current cable, prolonging the service life of the direct-current cable and being low in installation difficulty.

Description

Technical Field

[0001] This invention relates to a wire crimping process for MC4 connectors of photovoltaic modules, belonging to the technical field of wiring technology for photovoltaic power generation equipment. Background Technology

[0002] In existing technologies, photovoltaic modules typically use MC4 connectors to connect to DC cables. However, as... Figures 1-4 As shown, since the conductor of a photovoltaic DC cable is composed of multiple copper wires, when it is directly crimped onto the sub-type or female-type crimping terminal, the multiple copper wires are not a whole and have the characteristics of weak hardness and easy loosening. After crimping, they are prone to falling off, especially during the dragging of the DC cable. This can lead to leakage defects, which can further cause the inverter to report a "DC string" grounding shutdown fault, thus affecting the normal operation of the photovoltaic module.

[0003] To address this issue, Chinese utility model patent application CN202322524279.0 discloses a piercing MC4 plug for photovoltaic cables. By changing the shape of the plug's tail from a crimp shape to a conical shape, it allows for direct piercing connection during wiring. This piercing and pressing method ensures sufficient pressure and contact area between the cable and the plug, resulting in a more stable fixation to the DC cable surface. This prevents the connector from detaching or breaking from the DC cable, improving connection stability and effectively solving the problem of connectors easily detaching from DC cables in existing technologies. However, in practical use, the following problems exist: 1. Affects the service life of DC cables: The puncture process can easily damage the insulation and protective layers of the conductors inside the DC cable, making the internal wire bundle of the DC cable more susceptible to corrosion from moisture, chemicals, etc. in the external environment, thereby affecting the electrical performance and service life of the DC cable.

[0004] 2. High installation difficulty: During the installation process, the conductive core tail cone needs to be precisely inserted into the cable. This requires a high level of skill and precision from the operator. Otherwise, improper insertion may lead to problems such as poor contact. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a wire pressing process for the MC4 connector of a photovoltaic module.

[0006] The technical solution of the present invention is as follows: A photovoltaic module MC4 connector wire crimping process includes crimping terminals and DC cables. The crimping terminals include a sub-type MC4 connector insulating terminal, a sub-type crimping terminal, a female type MC4 connector insulating terminal, and a female type crimping terminal. Two DC cables are used. One end of one DC cable is connected to one end of the sub-type crimping terminal, and one end of the other DC cable is connected to one end of the female type crimping terminal. The end of the sub-type crimping terminal not connected to a DC cable is plugged into one end of the sub-type MC4 connector insulating terminal, and the end of the female type crimping terminal not connected to a DC cable is plugged into one end of the female type MC4 connector insulating terminal. The other end of the sub-type MC4 connector insulating terminal is plugged into the other end of the female type MC4 connector insulating terminal, thereby connecting the two DC cables together for a complete electrical connection.

[0007] This wire crimping process also employs a special two-stage winding technique to treat the ends of the two DC cables that connect to the sub-type and female-type crimping terminals, effectively improving their connection performance with these terminals. Details are as follows: Two-stage winding process includes primary winding process and secondary winding process.

[0008] The primary winding process includes: The first step is to strip the insulation sheath from the DC cable. The stripping length of the insulation sheath is n, which is sufficient to expose all the copper wires inside the DC cable after stripping.

[0009] The second step involves separating a portion of the copper wires from the DC cable. The total number of separated copper wires should be 20-25% of the total number of copper wires in the DC cable. The specific percentage can be determined based on the actual total number of copper wires; a larger total number of copper wires requires a larger percentage to be separated, and vice versa. These separated copper wires are then arranged side-by-side and divided into multiple equal parts. The specific distribution is determined based on the actual number of separated copper wires and the specific circumstances.

[0010] The third step is to wrap each copper wire around the outside of the DC cable in sequence, with each copper wire wrapped around the DC cable once to form a primary winding. The length of the primary winding is selected to be 0.25n. This length of the primary winding not only allows the contact area between the DC cable and the subsequent connector to reach the optimal state, so that the current can pass through more smoothly and effectively reduce the contact resistance, but also provides sufficient length for connection with the subsequent connector to facilitate the subsequent crimping work. The secondary winding process includes: The first step is to separate some of the remaining copper wires in the DC cable. The total number of separated copper wires is the same as the number of copper wires separated in the second step of the primary winding process. These copper wires are arranged side by side and divided into multiple equal parts. The specific distribution is determined based on the actual number of separated copper wires and the actual situation.

[0011] The second step involves sequentially winding the separated copper wires around the outside of the first winding body. Each portion of copper wire is wound once around the first winding body to form a second winding body. The winding direction of the second winding body is opposite to that of the first winding body, thereby enhancing the structural stability and firmness of the second winding body on the first winding body. Since the separated copper wires are identical, the number of copper wires in the second winding body is the same as that in the first winding body, ensuring a uniform distribution of the subsequent current flow and reducing contact resistance. The length of the second winding body is chosen to be half that of the first winding body to avoid insufficient anchoring due to excessive length and to avoid altering the current distribution at the joint due to excessive length, which could lead to current concentration. The outer diameter of the second winding body is larger than the outer diameter of the pressure terminal. Specifically, the outer diameter of the second winding body on the DC cable connected to the sub-type pressure terminal is larger than the outer diameter of the sub-type pressure terminal, and the outer diameter of the second winding body on the DC cable connected to the female type pressure terminal is larger than the outer diameter of the female type pressure terminal.

[0012] After the primary and secondary windings are completed, the following steps are taken when performing the crimping operation in this crimping process: Insert both the primary and secondary windings of the two DC cables into the corresponding female and male crimping terminals. The secondary windings on both DC cables, through their specific outer diameter settings, can engage with the corresponding slots of the female and male crimping terminals, thus acting as an anchoring joint and preventing the female and male crimping terminals from detaching from the corresponding DC cables. Then, using appropriate tools, such as crimping pliers, crimp the female and male crimping terminals to the corresponding primary windings on the two DC cables. This completes the crimping operation between the female and male crimping terminals and the corresponding DC cables.

[0013] The present invention has the following beneficial effects: This invention employs a two-stage winding process to form a primary winding and a secondary winding on a DC cable. The primary winding serves for crimping the connection, while the secondary winding, by engaging with the slot of the crimp terminal, acts as an anchoring point. This ensures a tight connection between the DC cable and the crimp terminal, preventing breakage during cable movement due to the anchoring provided by the secondary winding. Compared to the piercing connection method in existing technologies, this secondary winding method, while maintaining connection strength, uses crimping to connect the crimp terminal and the DC cable. The crimping process causes minimal damage to the overall structure of the DC cable, minimizing its impact on electrical performance and lifespan. Furthermore, the crimping operation is simple, requiring only the following winding and crimping steps. This method offers advantages such as ensuring the electrical performance of the DC cable, extending its lifespan, and reducing installation difficulty. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the existing technology when the DC cable and the sub-type crimp terminal are separated; Figure 2 This is a schematic diagram of the structure of a DC cable being crimped with a sub-type crimp terminal in the prior art; Figure 3 This is a schematic diagram of the structure of a DC cable and a female type crimp terminal when they are separated in the prior art; Figure 4 This is a schematic diagram of the structure of a DC cable being crimped with a female type crimping terminal in the prior art; Figure 5 This is a schematic diagram illustrating the crimping process used in this invention. Figure 6 This is a schematic diagram of the structure of the DC cable and the sub-type pressure terminal when they are separated in this invention; Figure 7 This is a schematic diagram of the structure when the DC cable is crimped to the sub-type crimp terminal in this invention; Figure 8 This is a schematic diagram of the structure of the DC cable and the female type crimp terminal when they are separated in this invention; Figure 9 This is a schematic diagram of the structure when the DC cable is crimped to the female type crimping terminal in this invention.

[0015] The reference numerals in the figure are as follows: 1. DC cable; 2. Sub-type MC4 connector insulated terminal; 3. Sub-type crimp terminal; 4. Female type MC4 connector insulated terminal; 5. Female type crimp terminal; 6. Primary winding body; 7. Secondary winding body. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0017] Example: Please refer to Figures 5-9 This embodiment provides a wire crimping process for the MC4 connector of a photovoltaic module, including the following steps: I. Material Preparation; Two cross-sectional areas of 4mm² were selected. 2 The DC cable 1 contains 56 copper wires. At the same time, the following are prepared: sub-type crimping terminal 3, female type crimping terminal 5, sub-type MC4 connector insulating terminal 2, female type MC4 connector insulating terminal 4, and crimping pliers.

[0018] II. Specific steps for pressing the wires; The first step is to strip the outer insulation sheath from the end of DC cable 1 used for connection to the crimp terminals, with a stripping length of 40mm, exposing all the copper wires inside. Next, group 15 copper wires into one group and 41 copper wires into another. Arrange the 15 copper wires side-by-side and wrap them around the 41 copper wires along the direction of the exposed copper wires, crimping 5 copper wires per turn, for a total of three turns, with a wrapping length of 10mm. This step is the first-stage winding process, forming the first-stage winding body 6 on DC cable 1.

[0019] The second step involves separating 15 copper wires from the remaining 41 copper wires. These 15 copper wires are then arranged side by side and wound in the opposite direction to the first-stage winding process, i.e., along the direction of the insulation sheath of the DC cable 1. The separated 15 copper wires are wound onto the first-stage winding body 6, with 5 copper wires crimped onto each turn. A total of three turns are made, with a winding length of 5mm. This step is the second-stage winding process, forming the second-stage winding body 7 on the first-stage winding body 6.

[0020] The third step involves crimping the end of one DC cable 1, which has a primary winding 6 and a second winding, to the sub-type crimping terminal 3, and crimping the end of the other DC cable 1, which has a primary winding 6 and a second winding, to the female type crimping terminal 5. The operation steps for crimping the DC cable 1 with the sub-type crimping terminal 3 and the female type crimping terminal 5 are as follows: Insert the primary winding body 6 and secondary winding body 7 on both DC cables 1 into the corresponding sub-type crimping terminal 3 and female type crimping terminal 5, so that the secondary winding body 7 on both DC cables 1 can be locked in the slot position of the corresponding sub-type crimping terminal 3 and the slot position of the female type crimping terminal 5. Then, use crimping pliers to crimp the sub-type crimping terminal 3 and the female type crimping terminal 5 to the corresponding primary winding body 6 on the two DC cables 1. At this time, the crimping operation between the sub-type crimping terminal 3 and the female type crimping terminal 5 and the corresponding DC cable 1 is completed.

[0021] The fourth step involves connecting the unconnected end of the DC cable 1 at the sub-type terminal 3 to one end of the insulated terminal 2 of the sub-type MC4 connector. Then, connect the unconnected end of the DC cable 1 at the female terminal 5 to one end of the insulated terminal 4 of the female MC4 connector. Finally, connect the other end of the insulated terminal 2 of the sub-type MC4 connector to the other end of the insulated terminal 4 of the female MC4 connector. At this point, the two DC cables 1 are electrically connected together through the sequential connection of the sub-type terminal 3, the sub-type MC4 connector insulated terminal 2, the female MC4 connector insulated terminal 4, and the female terminal 5. This completes the electrical connection between the two DC cables 1.

[0022] The separation pressure and DC resistance between the DC cable 1 and the crimping terminal provided in this embodiment are tested. Under the same conditions, the separation pressure and DC resistance between the DC cable 1 and the crimping terminal after conventional needle-nose pliers crimping and crimping with wire crimping pliers are also tested.

[0023] The test structure is shown in Table 1 below:

[0024] As shown in the table above, regarding connection strength, the pull-out force after crimping with wire cutters is 417.97 N, while the pull-out force after crimping with the wire cutting process provided in this embodiment is 445.0 N, representing an increase in connection strength of 77.03 N (18.42%). Regarding connection resistance, the DC resistance after crimping with wire cutters is 1.685 mΩ, while the DC resistance after crimping with the wire cutting process provided in this embodiment is 1.641 mΩ, representing a decrease of 0.044 mΩ (2.61%).

[0025] Therefore, the crimping process provided in this embodiment increases the contact area between the DC cable 1 and the crimping terminal, which can reduce the DC resistance to a certain extent, thereby reducing power loss during transmission. The crimping process provided in this embodiment, with the secondary winding body 7 clamped at the slot of the crimping terminal, acts as an anchoring knot, thereby increasing the pull-out force between the DC cable 1 and the crimping terminal. This effectively resists the influence of external forces such as cable dragging and vibration, ensuring that the joint will not loosen or fall off during long-term use.

[0026] Meanwhile, the crimping process provided in this embodiment, by clearly defining the length standards of the primary winding body 6 and the secondary winding body 7, also enables operators to follow uniform specifications during production, thereby ensuring the consistency of the process between different joints and reducing quality fluctuations caused by differences in human operation.

[0027] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A photovoltaic module MC4 connector wire crimping process, comprising a crimping terminal and a DC cable (1), characterized in that, Includes the following steps: A two-stage winding process is adopted, including a primary winding process and a secondary winding process; The primary winding process includes: separating a portion of the copper wires from the DC cable (1) and winding them around the outside of the DC cable (1) to form a primary winding body (6). The secondary winding process includes: separating a portion of the copper wires remaining in the DC cable (1) and winding them around the outside of the first winding body to form a secondary winding body (7). The outer diameter of the secondary winding body (7) is larger than the outer diameter of the wire terminal. Insert the primary winding body (6) and the secondary winding body (7) into the wire crimping terminal. After the secondary winding body (7) is locked in the slot of the wire crimping terminal, use the appropriate tool to crimp the wire crimping terminal to the primary winding body (6).

2. The photovoltaic module MC4 connector wire crimping process according to claim 1, characterized in that: The winding directions of the primary winding body (6) and the secondary winding body (7) are set in opposite directions.

3. The photovoltaic module MC4 connector wire crimping process according to claim 1, characterized in that: When separating the copper wires of the DC cable (1), the insulating sheath on the DC cable (1) is first stripped off. The stripping length of the insulating sheath is n. The stripping length of the insulating sheath is such that all the copper wires inside the DC cable (1) are exposed after stripping.

4. The photovoltaic module MC4 connector wire crimping process according to claim 3, characterized in that: The length of the first-stage winding (6) is selected as 0.25n, and the length of the second-stage winding (7) is selected as half of the length of the first-stage winding (6).

5. The photovoltaic module MC4 connector wire crimping process according to claim 1, characterized in that: The number of copper wires in the primary winding body (6) is 20-25% of the total number of copper wires in the DC cable (1), and the number of copper wires in the secondary winding body (7) is the same as the number of copper wires in the primary winding body (6).

6. The photovoltaic module MC4 connector wire crimping process according to claim 1, characterized in that: The wire terminals include a sub-type MC4 connector insulating terminal (2), a sub-type wire terminal (3), a female type MC4 connector insulating terminal (4), and a female type wire terminal (5). A DC cable (1) is connected to both the sub-type wire terminal (3) and the female type wire terminal (5). The outer diameter of the secondary winding (7) on the DC cable (1) connected to the sub-type wire terminal (3) is larger than the outer diameter of the sub-type wire terminal (3) and can be locked in the slot of the sub-type wire terminal (3). The outer diameter of the secondary winding (7) on the DC cable (1) connected to the female type wire terminal (5) is larger than the outer diameter of the female type wire terminal (5) and can be locked in the slot of the female type wire terminal (5).

7. The photovoltaic module MC4 connector wire crimping process according to claim 6, characterized in that: The end of the sub-type pressure terminal (3) that is not connected to the DC cable (1) is plugged into one end of the sub-type MC4 connector insulating terminal (2), the end of the female type pressure terminal (5) that is not connected to the DC cable (1) is plugged into one end of the female type MC4 connector insulating terminal (4), and the other end of the sub-type MC4 connector insulating terminal (2) is plugged into the other end of the female type MC4 connector insulating terminal (4).

8. The photovoltaic module MC4 connector wire crimping process according to claim 1, characterized in that: The first-level winding process also includes: during winding, the separated copper wires are arranged side by side and the separated copper wires are divided into multiple equal parts, and each part of the copper wire is wound around the DC cable (1) once.

9. The photovoltaic module MC4 connector wire crimping process according to claim 1, characterized in that: The secondary winding process further includes: during winding, the separated copper wires are arranged side by side and divided into multiple equal parts, with each part of the copper wires being wound once on the primary winding body (6).

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