Power terminal of a micro inverter
By designing power terminals with trapezoidal cross-sections and gripper structures, the problem of poor connection caused by welding stress and thermal expansion in micro-inverters was solved, achieving stable connection in high-temperature environments and extending the service life of the equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI FENGDIE ENERGY TECH CO LTD
- Filing Date
- 2025-06-27
- Publication Date
- 2026-07-03
AI Technical Summary
During long-term use, the input and output connections of microinverters are prone to poor connection due to mechanical displacement caused by welding stress and thermal expansion, which affects the stability and service life of the equipment.
Design a power terminal for a micro inverter. It is made of stamped brass plate with nickel plating. It has a trapezoidal cross section and a gripper structure. It is fixed to the PCB pad by the principle of three-point determination of the surface. The gripper is set with striped texture to enhance the welding stability and adapt to the thermal expansion and contraction of the colloid.
This ensures that the welded connections do not generate mechanical stress concentration under high temperature and thermal expansion and contraction environments, thereby improving the long-term operational stability of the micro-inverter and preventing the connection from becoming a bottleneck in its service life.
Smart Images
Figure CN224458661U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of power electronic equipment, specifically to a power terminal for a micro inverter. Background Technology
[0002] Microinverters are widely used in distributed photovoltaic (PV) power generation systems due to their superior performance. PV systems themselves have no moving parts, exhibiting high reliability and maintenance-free operation; PV modules, in particular, have a warranty period of up to 25 years. Therefore, to avoid lifespan bottlenecks in distributed PV power plants caused by inverter failures, microinverters must possess high reliability at the hardware level.
[0003] Besides ensuring the reliability of the inverter's hardware and software design, the reliable connection of its input and output power lines is also crucial, guaranteeing continuous and stable operation over long periods. Microinverters typically perform independent maximum power point tracking (MPPT) for each photovoltaic module, enabling each module to maintain high efficiency under varying lighting conditions. Generally, its input voltage does not exceed 65V, but due to continuous advancements in photovoltaic module technology and increasing power output, the input current of microinverters is also gradually increasing.
[0004] To meet this trend, the input and output conductors of microinverters, especially the input conductors, are typically made of multi-strand copper wire with a large cross-sectional area and have high mechanical strength to resist pulling.
[0005] However, after the wires are fixed to the housing, the connection points are usually not on the same horizontal plane as the internal PCB board, requiring the wires to be bent for direct connection. Due to the limited volume of the micro-inverter body, the small bending radius of the wires, and the thicker conductors, the solder joints are subjected to significant mechanical stress during soldering. Furthermore, to achieve IP67 protection, the micro-inverter housing typically employs a passive heat dissipation and heat homogenization method using integral potting. The internal operating temperature of the inverter can reach up to 95°C. At high temperatures, the adhesive material is prone to thermal expansion and displacement. During dynamic changes in light intensity, this volume change applies periodic push-pull stresses to the connecting wires, posing a challenge to the long-term stability of the input and output connections. Poor connections or increased impedance can lead to inverter malfunctions, shutdowns, or even damage. Utility Model Content
[0006] The purpose of this invention is to provide a power terminal for a micro inverter to address the aforementioned shortcomings in the technology.
[0007] To achieve the above objectives, this utility model provides the following technical solution: a power terminal for a micro inverter, comprising a terminal body, wherein welding feet are provided on both sides of the bottom of the terminal body;
[0008] The terminal body is provided with second grippers on both sides of the top, and a first gripper is provided at the middle of the top of the terminal body. The first gripper faces one side of the terminal body, and the two second grippers face the other side of the terminal body.
[0009] A first support foot is provided on one side of the terminal body below the first gripper;
[0010] A second support foot is provided on the other side of the terminal body and below the two second grippers.
[0011] Preferably, the terminal body is made of stamped brass plate, and the surface of the terminal body is nickel plated.
[0012] Preferably, the terminal body, soldering foot, first support foot, second support foot, second gripper, and first gripper are all integrated structures. The angle between the first support foot, the second support foot, and the terminal body is 90 degrees. By using one first support foot and two second support feet, and utilizing the principle of three points determining the surface, the terminal body can be supported to stand vertically on the PCB pad and the structural stability after soldering can be enhanced.
[0013] Preferably, the cross-section of the terminal body and the cross-section of the welding foot are both trapezoidal, and the trapezoidal cross-section of the terminal body and the trapezoidal cross-section of the welding foot gradually decrease from top to bottom, so as to accommodate different widths of pad spacing and input conductor lengths, while optimizing the heat conduction path to shorten the welding time.
[0014] Preferably, the cavity formed between the first gripper and the two second grippers is Y-shaped to cover the exposed conductor portion of the DC input cable, and the inner walls of the first gripper and the two second grippers are provided with striped textures to increase the welding area of the conductor and enhance contact stability.
[0015] The technical effects and advantages provided by this utility model in the above technical solution are as follows:
[0016] The power terminals provided in this application, after soldering, ensure that there are no mechanical stress concentration points in the entire conductor-terminal-pad-PCB system. Furthermore, after the micro-inverter is encapsulated with potting compound, the slight mechanical displacement caused by thermal expansion and contraction of the compound will not damage the soldered connection, thereby ensuring the long-term stable operation of the micro-inverter and preventing the conductor connection from becoming a bottleneck in its service life. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings.
[0018] Figure 1 This is one of the structural schematic diagrams of this utility model;
[0019] Figure 2 This is the second structural schematic diagram of the present invention;
[0020] Figure 3 This is a schematic diagram showing the terminals of this utility model located on a PCB board.
[0021] Explanation of reference numerals in the attached figures:
[0022] 1. Terminal body; 2. Welding foot; 3. First support foot; 4. Second support foot; 5. Second gripper; 6. First gripper. Detailed Implementation
[0023] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings.
[0024] Example 1
[0025] This utility model provides, for example Figures 1-3 The power terminals of a micro inverter shown include a terminal body 1, and welding feet 2 are provided on both sides of the bottom of the terminal body 1.
[0026] The terminal body 1 is provided with a second gripper 5 on both sides of the top, and a first gripper 6 is provided at the middle of the top of the terminal body 1. The first gripper 6 faces one side of the terminal body 1, and the two second grippers 5 face the other side of the terminal body 1.
[0027] A first support foot 3 is provided on one side of the terminal body 1 below the first gripper 6;
[0028] A second support foot 4 is provided on the other side of the terminal body 1 and below the two second grippers 5.
[0029] Furthermore, the terminal body 1 is made of stamped brass plate, and the surface of the terminal body 1 is nickel plated.
[0030] Furthermore, the terminal body 1, soldering foot 2, first support foot 3, second support foot 4, second gripper 5, and first gripper 6 are all integrated structures. The angle between the first support foot 3, the second support foot 4, and the terminal body 1 is 90 degrees. By using one first support foot 3 and two second support feet 4, and utilizing the principle of three points determining the surface, the terminal body can be supported to stand vertically on the PCB pad and the structural stability after soldering can be enhanced.
[0031] Furthermore, both the cross-section of the terminal body 1 and the cross-section of the soldering pin 2 are trapezoidal, and the trapezoidal cross-section of the terminal body 1 and the trapezoidal cross-section of the soldering pin 2 gradually decreases from top to bottom to accommodate different widths of pad spacing and input conductor lengths, while optimizing the heat conduction path to shorten the soldering time.
[0032] Furthermore, the cavity formed between the first gripper 6 and the two second grippers 5 is Y-shaped to cover the exposed conductor portion of the DC input cable, and the inner walls of the first gripper 6 and the two second grippers 5 are provided with striped textures to increase the welding area of the conductor and enhance contact stability.
[0033] Through the above technical solution:
[0034] When in use, the terminal body 1 is inserted into the PCB pad through the soldering foot 2, and is stably fixed by one first support foot 3 and two second support feet 4;
[0035] After the DC input line of the microinverter is fitted with the metal shell through an engineering plastic structure, its exposed conductor is inserted into the cavity formed between the first gripper 6 and the two second grippers 5, and a conductive connection is formed by welding. Since there is no mechanical stress concentration at the connection between the "gripper" and the conductor, it can adapt to the thermal expansion and contraction changes of the internal potting colloid.
[0036] Each DC input cable corresponds to two power terminals, which are connected to the positive and negative terminals respectively. The two terminals are arranged in a mirror image with the center line of the pad as the axis, and their gripper directions are set opposite to each other to improve the compactness of the wiring and the consistency of the soldering process. Each input channel of the micro inverter uses two of these power terminals, which is suitable for photovoltaic inverter devices with single-channel or multi-channel structures.
[0037] Example 2
[0038] Example 2 describes the specific terminal assembly process, please refer to the following description:
[0039] The DC input cable of a typical inverter usually consists of two insulated conductors. These cables are tightly assembled with the inverter's metal casing via a one-piece molded engineering plastic structural component. Considering the manufacturing process and mold release requirements, at least 10mm of insulation layer needs to be reserved at the part of the cable that is in close contact with the plastic structural component after entering the casing. At the same time, the conductor itself has high mechanical toughness. In order to improve the power density inside the casing and save space, only about 10mm of insulation covering area is left at the end of the conductor, of which the exposed conductor length for welding is about 6mm. Each DC input cable requires two power terminals, one for connecting the positive and one for the negative. These two terminals are arranged symmetrically on the central axis between the PCB pads. The gripper design of the two power terminals ensures that the two terminals are closely arranged. Given that a 5mm insulation and assembly distance needs to be reserved at the edge of the PCB, the distance from the power terminal to the edge of the inverter housing is set to 5mm (i.e., a total distance of 10mm minus the 5mm reserved at the edge). The height of the power terminal is designed so that the center line of the upper gripper coincides with the center line of the DC conductor, ensuring that the conductor is accurately positioned when embedded in the gripper.
[0040] The assembly process is as follows:
[0041] 1. Terminal pre-installation: Insert the two power terminals into the corresponding pad holes on the PCB board like conventional plug-in components by soldering the pins, and confirm that all three "support pins" are in contact with the PCB solder mask surface.
[0042] 2. Wave soldering: Together with other components, the power terminals are fixedly connected to the PCB through wave soldering. After soldering, the terminals have high fixing strength on the PCB and good resistance to mechanical stress.
[0043] 3. Cable Placement: After assembling the PCB and inverter housing, insert the exposed conductor of the DC input cable into the inside of the gripper through the upper opening of the power terminal gripper, ensuring a good fit with the housing. Ideally, there should be a very small gap between the conductor and the inner surface of the gripper to avoid pre-stress; slight contact is also acceptable.
[0044] 4. Conductor Soldering: The conductor is soldered to the gripper for fixation. After the solder melts, it can fully combine with the embossed pattern inside the gripper until the solder covers the top of the conductor. After cooling, a strong metal connection is formed, which has good overcurrent performance. After the soldering is completed, there are no mechanical stress concentration points in the entire conductor-terminal-pad-PCB system. After the micro inverter is potted and encapsulated, the slight mechanical displacement caused by the thermal expansion and contraction of the adhesive will not damage the soldered connection, thereby ensuring the long-term stable operation of the micro inverter and avoiding the conductor connection becoming a bottleneck in service life.
[0045] In a micro inverter with multiple inputs, each input channel requires two power terminals, and the installation method is exactly the same as the steps described above, demonstrating good versatility and consistency.
[0046] The foregoing description only illustrates certain exemplary embodiments of the present invention. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.
Claims
1. A power terminal of a micro-inverter, characterized by: It includes a terminal body (1), and welding feet (2) are provided on both sides of the bottom of the terminal body (1); The terminal body (1) is provided with second grippers (5) on both sides of the top, and a first gripper (6) is provided at the middle of the top of the terminal body (1). The first gripper (6) faces one side of the terminal body (1), and the two second grippers (5) face the other side of the terminal body (1). A first support foot (3) is provided on one side of the terminal body (1) below the first gripper (6); A second support foot (4) is provided on the other side of the terminal body (1) and below the two second grippers (5).
2. A power terminal for a micro-inverter according to claim 1, characterized in that: The terminal body (1) is made of brass plate and the surface of the terminal body (1) is nickel plated.
3. A power terminal for a micro-inverter according to claim 2, wherein: The terminal body (1), welding foot (2), first support foot (3), second support foot (4), second gripper (5) and first gripper (6) are all integrated structures, and the included angle between the first support foot (3), the second support foot (4) and the terminal body (1) is 90 degrees.
4. A power terminal for a micro-inverter according to claim 1, wherein: The cross-section of the terminal body (1) and the cross-section of the welding foot (2) are both trapezoidal, and the trapezoidal cross-section of the terminal body (1) and the trapezoidal cross-section of the welding foot (2) gradually decrease from top to bottom.
5. The power supply terminal of a micro inverter according to claim 1, characterized in that: The cavity formed between the first gripper (6) and the two second grippers (5) is Y-shaped, and the inner walls of the first gripper (6) and the two second grippers (5) are provided with striped patterns.