A battery piece string welding device and a string welding method

Abstract

The application belongs to the technical field of battery piece welding and provides a battery piece series welding device and series welding method, which are used for solving the problems of low efficiency and short service life of the battery piece welding equipment in the prior art. The battery piece series welding device comprises a plurality of heating modules, each of which comprises a heat sink and a plurality of VCSEL laser chips. The plurality of VCSEL laser chips are arranged in an ordered array on the heat sink and are used for emitting surface laser light to the surface of the battery piece to heat the battery piece, melt the main grid pad on the surface of the battery piece, and arrange the welding strip on the upper surface of the pad to realize welding. The heat sink is provided with positive and negative electrode terminals. The positive and negative electrode terminals are used for connecting the power supply to electrify each VCSEL laser chip. The battery piece series welding device and series welding method provided by the application can reduce the response time of the welding equipment in the welding process, improve the light energy absorption efficiency of the battery piece, more easily control the over-temperature risk, and effectively improve the service life of the battery piece series welding device.

Description

Technical Field

[0001] This invention relates to the field of battery cell welding technology, specifically to a battery cell string welding device and string welding method. Background Technology

[0002] In the manufacturing process of photovoltaic modules, solar cells need to be connected to each other to form a cell string using solder ribbons. Currently, various automated welding methods are used to weld the ribbons onto the cells, including hot air welding, electromagnetic induction welding, and infrared welding. Among these, infrared welding is the most mature technology, offering advantages such as low equipment cost and direct heating of the material, achieving good welding results. However, this method still has some drawbacks. First, the welding response is sluggish; the gradual heating of the materials being welded typically takes 1-3 seconds. Second, the electro-optical conversion efficiency is low, and the light energy is easily absorbed by other materials in the optical guidance process, further reducing light energy utilization. Third, the power of infrared light is difficult to control stably, increasing the risk of overheating and making precise temperature control difficult. Fourth, the lifespan of infrared heating lamps is typically only about 3000-5000 hours, resulting in high equipment maintenance costs. Finally, for the welding of solar cells, since the main material is silicon wafers, the absorption spectrum of silicon differs significantly from infrared light, leading to a relatively low effective absorption and utilization rate of light energy by the silicon wafers. Summary of the Invention

[0003] To address the problems mentioned in the background art, the present invention relates to a battery cell stringing device and stringing method, which can reduce the response time of the welding process, improve the light energy absorption efficiency of the battery cells, make the risk of overheating easier to control, and effectively extend the service life of the battery cell stringing device, thus having excellent application prospects.

[0004] To achieve this objective, the present invention adopts the following technical solution:

[0005] On one hand, the present invention provides a battery cell stringing device, comprising several heating modules, each heating module including a heat sink and multiple VCSEL laser chips. The multiple VCSEL laser chips are arranged in an orderly array on the heat sink, used to emit uniform surface lasers to the surface of the battery cell to melt the main grid pads on its surface and the solder strips covering them side by side to achieve welding. The heat sink is provided with positive and negative terminals, which are used to connect the power supply to power each of the VCSEL laser chips.

[0006] On the other hand, the present invention provides a method for stringing battery cells, the method comprising the following steps:

[0007] The battery cell with the solder ribbon attached to its surface is moved to the welding station or the battery cell is placed and the solder ribbon is covered at the welding station.

[0008] The cell stringing device is activated, and the laser emitted by multiple VCSEL laser chips arranged in an array is used to uniformly irradiate and heat the surface of the cell to be welded, so as to melt the solder ribbon covering the surface of the cell and realize the welding process with the main grid pad.

[0009] The welded battery cell assembly is then shipped out.

[0010] Specifically, the battery cell string welding method further includes a preheating step, in which the battery cell string welding device is activated to preheat the battery cells, and the preheating step is controlled to be located before the welding step and the preheating temperature of the preheating step is lower than the welding temperature.

[0011] Specifically, in the preheating step and the welding step, based on the influence of the laser power, preheating time and welding time of the current battery cell stringing device on the surface temperature of the battery cell, and according to the welding temperature requirements of the battery cell, pulse width modulation technology is applied to modulate the working mode of the laser in the battery cell stringing device to control the welding process parameters, including the laser output power, pulse width and duty cycle, battery cell preheating time and welding time.

[0012] Specifically, the preheating temperature is controlled at 120℃~160℃, and the welding temperature is controlled at 230℃~260℃.

[0013] Specifically, the wavelength of the laser output of the battery cell stringing device is controlled to be one or a combination of 808nm, 850nm, 905nm, 940nm and 980nm.

[0014] Specifically, the heating array of the battery cell stringing device is controlled to match the overall size of the battery cell, and the overall power of the battery cell stringing device is controlled to be between 2.4 kW and 8 kW during welding.

[0015] Specifically, the preheating step before welding also includes preheating the stage that carries the battery cell, and the preheating temperature of the stage is controlled between 80°C and 110°C.

[0016] Specifically, before moving the battery cell with the solder strip group on its surface to the welding station or placing the battery cell on the welding station, the battery cell stringing device is activated to preheat the stage. After the battery cell assembly is discharged, the battery cell stringing device is activated to preheat the stage.

[0017] Specifically, the battery cell stringing device is controlled to remain running during the continuous welding of the battery cells. Before each battery cell leaves the support platform and before the next battery cell moves onto the support platform, the battery cell stringing device is controlled to be in standby mode, and the standby power is controlled to be P1.

[0018] Beneficial effects:

[0019] 1. The battery cell stringing device used in this invention includes multiple VCSEL laser chips arranged in an orderly array, so that the VCSEL laser chips with individual power of only a few watts can be combined to form a heating array of hundreds of watts to meet the needs of battery cell welding. The response time of this heating array reaches the nanosecond level. Compared with the traditional infrared light irradiation method using infrared lamps, the battery cells can quickly reach the required temperature. In addition, the emitted laser can directly and uniformly irradiate the surface of the battery cells, without the waste of light source due to absorption by the corresponding optical light guiding system. The overall welding time can be greatly reduced.

[0020] 2. The battery cell stringing device provided by this invention has the advantage that the emission spectrum of the VCSEL laser chip covers between 650nm and 1550nm, while the light absorption wavelength of silicon solar panels is mainly concentrated in the visible and near-infrared light regions, i.e., between 400-1100nm. Within this range, silicon materials have a high absorption rate for light in this wavelength range. Therefore, selecting the working range of the VCSEL laser between 650nm and 1100nm can give the silicon wafer better absorption performance, resulting in better light energy absorption efficiency compared to the light source generated by traditional infrared lamps.

[0021] 3. The battery cell string welding device provided by the present invention uses VCSEL laser chips to replace traditional infrared lamp tubes for thermal radiation welding, and the actual service life can reach 100,000 hours, compared with the service life of traditional infrared lamp tubes of 5,000 hours, which can effectively reduce the maintenance cost of the equipment.

[0022] 4. The battery cell stringing device provided by the present invention directly irradiates the battery cell with the laser array of the VCSEL laser chip. Due to the stable electro-optical transmission efficiency, it can provide a reliable basis for controlling the temperature rise of the battery cell. The temperature of the battery cell before and after welding can be controlled by changing parameters such as the laser output power or the length and frequency of the working time. Compared with the infrared lamp irradiation method, the heating power control method is more flexible and more precise, which can effectively reduce the risk of overheating caused by excessive heating of the battery cell.

[0023] 5. The battery cell string welding method provided by the present invention increases the starting temperature of battery cell welding by preheating the battery cells before welding, shortens the welding cycle, and reduces the problems of cell cracking and warping caused by rapid temperature rise during the welding cycle.

[0024] 6. The battery cell stringing method provided by the present invention can use a battery cell stringing device to preheat the platform, preheat the battery cells, and weld the battery cells, realizing the versatility of the battery cell stringing device and having good economic benefits.

[0025] 7. The battery cell stringing method provided by the present invention provides specific laser wavelength parameters and power modulation to provide specific power of the battery cell stringing device and heating preheating temperature, providing an effective solution and reference for preventing battery cell cracking, warping and welding parameters;

[0026] 8. The battery cell stringing method provided by the present invention controls the battery cell stringing device to remain running during operation and maintain the standby temperature while waiting for the battery cells to be welded. On the one hand, the battery cell stringing device can radiate heat to the surface of the platform, so that the platform has a certain temperature for heat conduction to the battery cells. On the other hand, it can quickly rise to the preheating temperature when preheating the battery cells, further shortening the response time, thereby shortening the welding cycle. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the battery cell stringing device provided by the present invention;

[0028] Figure 2 This is a schematic diagram of the assembly structure of multiple heating modules provided by the present invention within the mounting box;

[0029] Figure 3 This is a schematic diagram of the heating module provided by the present invention;

[0030] Figure 4 This is a schematic diagram of the welding process of the battery cell string welding device provided by the present invention;

[0031] Figure 5 This is a schematic diagram of the structure of the glass provided by the present invention within the mounting box;

[0032] Figure 6 This is a schematic diagram of the internal structure of the mounting box provided by the present invention;

[0033] Figure 7 This is a front view of the battery cell stringing apparatus provided by the present invention;

[0034] Figure 8 yes Figure 7 A cross-sectional view of the AA plane;

[0035] Figure 9 This is a schematic flowchart of the battery cell stringing method provided by the present invention;

[0036] Figure 10This is a graph showing the relationship between the power-off time and power of the battery cell string welding device provided by the present invention.

[0037] In the picture:

[0038] 10-Heating module; 1-Heat sink; 2-VCSEL laser chip; 3-Mounting box; 4-Heat conduction plate; 41-Cooling water channel; 5-Glass; 6-Water inlet connector; 7-Water outlet connector; 8-Temperature sensor; 9-Battery cell; 11-Power supply. Detailed Implementation

[0039] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that the invention will be thorough and complete, and the concept of the exemplary embodiments will be fully conveyed to those skilled in the art. In the drawings, for clarity, the thickness of regions and layers is exaggerated. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed descriptions will be omitted.

[0040] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the invention can be practiced without one or more of the specific details described, or other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0041] The following example describes a battery cell stringing apparatus and method according to the present invention. This example is only a part of the embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. All other embodiments obtained by those skilled in the art without inventive effort should be covered within the scope of protection of the present invention.

[0042] Example 1:

[0043] The battery cell stringing apparatus provided in this embodiment of the invention can reduce the response time of the welding process, improve the light energy absorption efficiency of the battery cell 9, make the risk of overheating easier to control, and effectively extend the service life of the battery cell welding apparatus. To achieve the above-mentioned functions of the battery cell stringing apparatus, such as... Figures 1 to 4As shown, the battery cell stringing device includes several heating modules 10. Each heating module 10 includes a heat sink 1 and multiple VCSEL laser chips 2. The VCSEL laser chip 2 (COS / COB package) is a two-dimensional array surface light source composed of hundreds of milliwatt-level vertical cavity emitting lasers (VCSELs) welded onto the heat sink 1 of aluminum nitride ceramic or other materials. Each VCSEL laser chip 2 can achieve a power output of up to several watts and is the basic chip unit for manufacturing rectangular laser modules. Further details are omitted here. The heat sink 1 can be a gold-plated copper heat sink, on which the VCSEL laser chips 2 can be welded for heat dissipation. Multiple VCSEL laser chips 2 are arranged in an orderly array on the heat sink 1. To ensure stable heating effect, it is preferable to arrange the VCSEL laser chips 2 in a honeycomb array, ensuring that the spacing between every two adjacent VCSEL laser chips 2 is equal. Alternatively, they can be arranged in a honeycomb array. Figure 2 and Figure 3 As shown, the VCSEL laser chips 2 are arranged in a matrix to ensure the temperature of each irradiation surface is uniform. Since the power of a single light-emitting point of the VCSEL laser chip 2 is only 1mw-10mw, even after forming a chip with more than 600 light-emitting points, it can only form a few watts of output, which is far from meeting the actual needs of welding. When applied to welding battery cells 9, they are arranged in an array to form a heating module 10 with a power of hundreds to kilowatts to meet the welding needs (preferably 700-800 VCSEL laser chips 2 are arranged on each heat sink 1). In order to ensure the normal operation of this heating module 10, positive and negative terminals are provided on both sides of the heat sink 1. The terminals are used to connect the power supply 11 to supply power to all VCSEL laser chips 2.

[0044] The battery cell 9 using the aforementioned battery cell stringing device can stably provide up to 100W / cm² radiant brightness compared to traditional laser-welded battery cells, providing precise localized laser heat treatment for heated objects. The temperature rise rate of the irradiated object is as high as several hundred to 1000K / second. Furthermore, due to the short response time and electro-optic response rate of the VCSEL laser chip 2 (up to GHz), the electro-optic conversion efficiency can be stably maintained at around 40%, thus rapidly heating the battery cell 9 to weld the solder strips on it. Compared to traditional infrared lamp welding, this effectively improves the welding speed and efficiency. This technology is applicable to VCSEL lasers. The cell stringing device of chip 2 has a typical service life of up to 100,000 hours, compared to the 5,000 hours of ordinary infrared lamps, which can effectively reduce equipment maintenance costs. The power of this cell stringing device is more stable than that of traditional infrared lamps, which makes it easier to adjust the heating temperature of cell 9 by controlling the time and power, and it is less likely to cause microcracks, warping or other damage to cell 9 due to overheating. The radiation source based on VCSEL laser chip 2 has a narrow linewidth radiation spectrum (1nm~10nm) that is adapted to the absorption of photovoltaic materials, a high-speed response time of less than nanoseconds, and precise and controllable directionality. By adapting this type of light source to the welding of battery strings, it is preferable that the VCSEL laser chip 2 operates in one or more combinations of 808nm, 850nm, 905nm, 940nm, and 980nm within the 650nm-1100nm range. This improves the efficiency of light energy absorption by the silicon material surface, making it easier for the laser to be absorbed by the battery cell 9, thereby generating heat and increasing the temperature. Compared to the light source emitted by traditional infrared lamps, this effectively reduces light source waste. Furthermore, the appropriate welding power can be adjusted by changing the number of VCSEL laser chips 2, resulting in good performance and adjustable flexibility. During operation, the aforementioned battery cell string welding device emits a uniform array of laser light to the battery cell 9 through multiple VCSEL laser chips 2. The battery cell 9 absorbs the light energy, and upon heating, it simultaneously melts the solder ribbon covering its surface, thus achieving welding between the solder ribbon and the main grid pad. This battery cell string welding device can be applied to various welding processes, demonstrating good operational efficiency.

[0045] As a preferred optional size and parameters: to match the specifications of the battery cell 9 (210mm × 105mm), the luminous area of ​​a single string-welded heating module 10 for the battery cell 9 is set to 31.62mm × 244.3mm; both ends are positive and negative electrode pads, there are screw mounting holes at the four corners, and there is also a screw mounting hole in the middle; the geometric dimensions of the AlN (aluminum nitride ceramic) heat sink 1 (here, the frame for mounting the VCSEL laser chip 2) are 3.5mm × 3.5mm; the infrared laser luminous unit is approximately 1mm × 1mm in size, and each unit contains more than 600 VCSEL luminous points; the heating has 6 rows of lasers connected in parallel, with 44 VCSEL laser chips 2 connected in series in each row, that is, each heat sink 1 has 264 VCSEL laser chips 2, the output wavelength of the VCSEL laser chip 2 is 940nm, and the laser output power of the heating module 10 is 300W to 1000W. Figure 2 and Figure 4 As shown, the preferred number of serial welding heating modules 10 is 8, each heating module 10 is independently electrically controlled and driven, with a total power of 2.4KW-8.0KW and a total geometric dimension of 258.5mm×270mm. Among them, Figure 4 The numbers 1, 2, 3...8 in the square box represent the specific number of heating modules 10.

[0046] like Figure 1 and Figure 2 As shown in the figure, an embodiment of the present invention provides a battery cell stringing device, including multiple stringing heating modules 10 for battery cells 9 as described above, and a mounting box 3 for mounting the heating modules 10. The multiple stringing heating modules 10 for battery cells 9 are spliced ​​together to form a heating surface with the irradiation area of ​​the battery cells 9 by multiple VCSEL laser chips 2. In some special heating processes, the heat sink 1 can be designed to match the shape of the material to be heated to meet different usage requirements. As another preferred embodiment, the multiple heating modules 10 in the mounting box 3 can be divided into a preheating area and a welding area. That is, one part of the heating modules 10 corresponds to the preheating power, and the other part corresponds to the welding power. The two parts of the heating modules 10 operate independently. During preheating, the heating modules 10 in the welding area are not working or are in standby mode. During welding, the heating modules 10 in the preheating area are not working or are in standby mode. Preheating the battery cells 9 before welding can prevent damage caused by rapid temperature rise of the battery cells 9.

[0047] An embodiment of the present invention provides a battery cell stringing device, such as... Figure 5As shown, in order to prevent dust from affecting the normal operation of the VCSEL laser chip 2, a light-transmitting opening is provided on the mounting box 3. The serial welding heating module 10 of multiple battery cells 9 is installed inside the mounting box 3, and the laser of the VCSEL laser chip 2 shines on the battery cells 9 through the light-transmitting opening. At this time, a glass 5 is installed at the position of the light-transmitting opening to protect the VCSEL laser chip 2. During installation, the glass 5 should be tightly attached to the working surface of the VCSEL laser chip 2 to prevent the influence of dust and ensure the strength of this mounting surface to prevent damage.

[0048] The present invention provides a battery cell stringing device, wherein antireflection films are deposited on both sides of glass 5. The antireflection films are used to selectively filter lasers with wavelengths of 920nm to 960nm. By improving the transmittance of light through the antireflection films and filtering out welding wavelengths that have large errors compared to 940nm lasers, the efficiency of the workpiece can be improved, and the welding temperature of the surface of the battery cell 9 can be estimated more accurately (because the absorption coefficient of silicon material by 940nm wavelength laser is actually used when estimating the surface temperature of the battery cell 9).

[0049] like Figures 6 to 8 As shown in the embodiment of the present invention, a battery cell stringing device is provided. To prevent the equipment from burning out due to the high temperature caused by the simultaneous operation of hundreds of VCSEL laser chips 2, a heat-conducting plate 4 is installed in the mounting box 3. The heat-conducting plate 4 is attached to the side of several heat sinks 1 away from the VCSEL laser chips 2 to absorb the heat of the heat sinks 1. To enhance heat dissipation, a cooling mechanism for cooling the heat-conducting plate 4 is also provided in the mounting box 3. As a preferred embodiment of the above technical solution, the heat-conducting plate 4 can be set as a copper plate or an aluminum water-cooled heat sink plate. A cooling water channel 41 is provided inside it. A water inlet connector 6 for water inlet and a water outlet connector 7 for water outlet are respectively provided at the inlet and outlet positions of the cooling water channel 41. The generated heat is dissipated by water circulation. The space between the heat-conducting plate 4 and the heat sink 1 is uniformly filled with a metal or non-metal thermally conductive material, such as indium foil, silver paste, or thermal grease. Alternatively, a metal solder, such as soldering silver paste, can be used to solder the heat sink 1 onto the heat-conducting plate 4.

[0050] The present invention provides a battery cell stringing device, wherein a temperature detection sensor is provided on the heat-conducting plate 4. The temperature detection sensor is electrically connected to the control unit to detect the operating temperature of the heating module 10 during battery cell stringing. When the temperature is too high, an emergency alarm or cooling acceleration is required to prevent damage to the components caused by the continuous high temperature.

[0051] The battery cell stringing apparatus provided in this embodiment of the invention can be referred to as follows: Figure 6 and Figure 8As shown, the cooling water path 41 extends along the length of the heating module 10 of the battery cell 9 and fully covers the heating module 10 of all battery cells 9 in the width direction. Temperature detection sensors are evenly distributed on the heat conduction plate 4 corresponding to the position of each cooling water path 41 and along the length of the cooling water path 41. Preferably, one or a group of temperature detection sensors can be set on the front, middle and rear sides of each cooling water path 41 (in the case of a group, it corresponds to a bent cooling water path, such as an S-shaped one. Since there are front, middle and rear sides in each length direction, it is necessary to set them at each position point to form a corresponding temperature detection sensor group) to detect the temperature of each area during operation. Each temperature detection sensor is electrically connected to the control unit. This arrangement of temperature detection sensors is very necessary for long cooling water paths 41, especially for S-shaped cooling water paths 41, which can ensure the control of the corresponding temperature of the entire cooling water path 41.

[0052] This invention provides a solar cell stringing heating system, comprising a feeding mechanism, a discharging mechanism, a solar cell temperature detection system, and a solar cell stringing apparatus of any one of the above, wherein:

[0053] The feeding mechanism supplies solar cells 9, with their surfaces covered by solder ribbons, to the heating station of the solar cell stringing apparatus. The solar cell stringing apparatus irradiates the solar cells 9 to heat them and melt the solder ribbons covering their surfaces. A solar cell temperature detection system monitors the surface temperature of the solar cells 9 and feeds it back to the control unit to output a modulation signal applied to the solar cell stringing apparatus. After cooling, the welding is completed. Additionally, the apparatus may include a preheating solar cell stringing apparatus to preheat the solar cells 9 before welding. The unloading mechanism transports the welded solar cell strings from the heating station to the next station. The solar cell temperature detection system monitors the surface temperature during the heating process of the solar cell stringing apparatus and adjusts relevant factors such as the power, current, or heating time of the solar cell stringing apparatus when the temperature is too high.

[0054] The aforementioned cell temperature detection system can be a temperature sensor 8 installed on the mounting box 3.

[0055] Example 2:

[0056] This invention provides a method for string welding of battery cells, which uses the battery cell string welding device in Embodiment 1 to perform heat treatment welding on battery cells 9, providing a reliable solution for the surface welding of solder strips on battery cells 9. The method includes the following steps:

[0057] The battery cell 9 with the solder ribbon on its surface is moved to the welding station or the battery cell 9 is placed and the solder ribbon is covered at the welding station; the battery cell string welding device is activated (which is mainly the array of VCSEL laser chips 2 in Embodiment 1, which heats the surface of the laser beam as an array, and the resulting heating beam is arranged in a matrix so that the emitted laser is evenly distributed on the surface of the battery cell 9 in a matrix or irradiation surface form to achieve uniform heating of the battery cell 9. The battery cell string welding device mentioned below refers to the heating mechanism applied in this way), and the laser emitted by the array of VCSEL laser chips 2 is used to heat the surface of the battery cell 9 to be welded, so that the solder ribbon on the surface of the battery cell 9 melts after being heated to achieve the welding process; the welded battery cell 9 or corresponding component is discharged to wait for the next battery cell 9 to be placed and welded. After welding, the cells 9 or corresponding components can be cooled before being shipped out. The welding process is repeated to connect the cells 9 to the welding ribbon, forming a battery string. Cooling can be natural or controlled, including but not limited to air cooling, water cooling, and cryogenic gas cooling (liquid nitrogen, etc.). Before welding, the cell string welding device can be moved to the appropriate welding station, or the cells 9 and welding ribbon can be positioned and then shipped to the welding station. The specific method is not limited here, but it is understood that preparations need to be made at the welding station before welding. When this welding method is applied to IBC structure battery strings, the heating module 10 only melts and welds one side of the cell 9. When applied to gridless structure battery strings, the welding ribbon on one side of the cell 9 can be melted first, or both sides can be welded simultaneously. When applied to simultaneous welding, the welding cycle can be shortened by at least half, resulting in better performance.

[0058] This invention provides a method for string welding of battery cells. To prevent microcracks or warping of the battery cells 9 due to rapid temperature rise during the welding cycle, a preheating step is included before welding. During this preheating, the battery cell string welding device is activated to preheat the battery cells 9. The preheating step is positioned before the welding step and its temperature is lower than the welding temperature. Preferably, a set of effective data is provided for reference: the preheating temperature is controlled at 120℃~160℃, and the welding temperature is controlled at 230℃~260℃.

[0059] like Figure 9As shown in the embodiment of the present invention, a method for stringing solar cells provides a stable electro-optical conversion efficiency by using a VCSEL laser chip 2 for heating. This allows for easier adjustment of the output laser energy by controlling input parameters, and estimation of heat generation based on the actual absorption efficiency of the silicon wafer. In the preheating and welding steps, pulse width modulation (PWM) technology is applied to modulate the factors affecting the surface temperature of the solar cell 9 based on the influence of the current power of the solar cell stringing device, preheating time, and welding time (related factors of the signal source). In this method, a corresponding infrared temperature monitoring module is required to monitor the surface temperature of the solar cell 9. Adjustment methods include controlling the power of the solar cell stringing device, preheating time, and welding time. Since the electro-optical conversion efficiency of this VCSEL laser chip 2 can be stabilized at around 40%, the signal source can be adjusted accordingly based on the required temperature. Furthermore, the potential temperature rise under corresponding conditions can be estimated and calculated, effectively preventing the risk of overheating due to uncontrollable temperature.

[0060] The present invention provides a method for stringing solar cells. Since the spectrum of the emitted laser from the VCSEL laser chip 2 covers the range of 650nm-1550nm, and the light absorption wavelength of the silicon solar panel is mainly concentrated in the visible and near-infrared light regions, i.e., the wavelength is between 400-1100nm, the wavelength of the laser output from the VCSEL laser chip 2 can be controlled to be one or more of 808nm, 850nm, 905nm, 940nm and 980nm, so that the output laser is more easily absorbed by the surface of the solar cell 9, thereby improving the conversion efficiency of laser light energy into heat energy.

[0061] The present invention provides a method for stringing solar cells, which provides an effective working power range based on the specifications of the solar cell 9, which is 210mm×105mm. The heating array of the solar cell stringing device is controlled to match the overall size of the solar cell 9, and the overall power of the solar cell stringing device is controlled to be between 2.4kw and 8.0kw during welding. This power range is the preferred range for welding the welding strip of the solar cell 9.

[0062] This invention provides a method for string welding of battery cells. To improve the preheating speed, the preheating step includes preheating the platform supporting the battery cells 9. This allows the battery cells 9 to be preheated from the other side after being placed on the platform, thereby rapidly increasing the preheating temperature of the battery cells 9. Welding is then performed after the preheating temperature is reached. The preheating temperature of the platform is controlled between 80°C and 110°C. The welding method used in this invention can simultaneously weld the solder strips on both the upper and lower sides of the battery cells 9, resulting in superior performance.

[0063] The present invention provides a method for stringing solar cells. In order to facilitate the preheating of the carrier, before the solar cell 9 with the welding ribbon group on its surface is moved to the welding station or placed on the welding station, the solar cell stringing device is used to preheat the carrier. Alternatively, the solar cell stringing device is used to preheat the carrier after the solar cell assembly is discharged. At this time, the solar cell stringing device can simultaneously satisfy three functions: first, to heat and preheat the carrier; second, to preheat the solar cell 9; and third, to weld the solar cell 9.

[0064] like Figure 10 As shown, this embodiment of the invention provides a method for stringing solar cells. According to the above description, if the power is selectively cut off at each station of the stringing solar cell device, the power control procedure is complex and easily leads to equipment damage. Therefore, here, when controlling heating, the stringing solar cell device is controlled to remain running during the continuous welding of solar cells 9. Before each solar cell 9 leaves the support platform and before the next solar cell 9 moves onto the platform, the stringing solar cell device is controlled to be in standby mode, and the standby power is controlled to be P1. Figure 10 As shown in position ④ corresponding to position ③ (where position ⑤ corresponding to position ①: preheating power P2; position ⑥ corresponding to position ②: welding power P3), this standby power can simultaneously radiate heat to the stage, which can bring the stage close to the preheating temperature of the battery cell 9 after heating (controlled by a relevant temperature control unit). This can quickly reach the required heating temperature when preheating the battery cell 9 in the future, thereby further shortening the response cycle.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A battery cell stringing apparatus, characterized in that, The device includes several heating modules (10), each heating module (10) comprising a heat sink (1) and multiple VCSEL laser chips (2). The multiple VCSEL laser chips (2) are arranged in an orderly array on the heat sink (1) to emit uniform surface lasers onto the surface of the solar cell (9) to melt the main grid pads on its surface and the solder strips covering them side by side to achieve welding. The heat sink (1) is provided with positive and negative terminals, which are used to connect a power supply (11) to energize each of the VCSEL laser chips (2). The solar cell stringing device also includes a device for installing... The heating module (10) is mounted in a box (3). The box (3) has a light-transmitting opening. The heating modules (10) of the multiple battery cells (9) are all installed inside the box (3). The laser of the VCSEL laser chip (2) shines on the battery cell (9) through the light-transmitting opening. At this time, a glass (5) is installed at the position of the light-transmitting opening to protect the VCSEL laser chip (2). The glass (5) is in close contact with the working surface of the VCSEL laser chip (2). Anti-reflective coatings are coated on both sides of the glass (5).

2. A method for string welding of battery cells, wherein the battery cells (9) are heat-treated and welded based on the battery cell string welding apparatus of claim 1, characterized in that, The method includes the following steps: Move the battery cell (9) with the solder ribbon on its surface to the welding station or place the battery cell (9) and cover it with the solder ribbon at the welding station; The battery cell string welding device is activated, and the laser emitted by multiple VCSEL laser chips (2) arranged in an array is used to uniformly irradiate and heat the surface of the battery cell (9) to be welded, so that the solder ribbon covering the surface of the battery cell (9) melts and thus realizes the welding process between the battery cell (9) and the main grid pad. The welded battery cell assembly is then shipped out.

3. The battery cell stringing method as described in claim 2, characterized in that, The battery cell string welding method further includes a preheating step, in which the battery cell string welding device is activated to preheat the battery cell (9), and the preheating step is controlled to be located before the welding step and the preheating temperature of the preheating step is lower than the welding temperature.

4. The battery cell stringing method as described in claim 3, characterized in that, In the preheating step and the welding step, based on the influence of the power of the laser, the preheating time and the welding time of the current battery cell string welding device on the surface temperature of the battery cell (9), and according to the welding temperature requirements of the battery cell, the working mode of the laser in the battery cell string welding device is modulated by pulse width modulation technology to control the welding process parameters, including the laser output power, pulse width and duty cycle, the preheating time of the battery cell and the welding time.

5. The battery cell stringing method as described in claim 4, characterized in that, The preheating temperature is controlled at 120℃~160℃, and the welding temperature is controlled at 230℃~260℃.

6. The battery cell stringing method as described in claim 2, characterized in that, The wavelength of the laser output of the battery cell stringing device is controlled to be one or a combination of 808nm, 850nm, 905nm, 940nm and 980nm.

7. The battery cell stringing method as described in claim 2, characterized in that, The heating array of the battery cell string welding device is controlled to match the overall size of the battery cell (9), and the overall power of the battery cell string welding device is controlled to be between 2.4kw and 8kw during welding.

8. The battery cell stringing method as described in claim 3, characterized in that, The preheating step before welding also includes preheating the stage that carries the battery cell (9), and the preheating temperature of the stage is controlled at 80°C to 110°C.

9. The battery cell stringing method as described in claim 8, characterized in that, Before the step of moving the battery cell (9) with the welding strip group on its surface to the welding station or placing the battery cell (9) on the welding station, the battery cell string welding device is activated to preheat the stage. After the step of the battery cell assembly is discharged, the battery cell string welding device is activated to preheat the stage.

10. The method for stringing solar cells as described in any one of claims 2-9, characterized in that, The battery cell stringing device is controlled to remain running during the continuous welding of the battery cells (9). Before each battery cell (9) leaves the platform and the next battery cell (9) moves to the platform, the battery cell stringing device is controlled to be in standby mode and the standby power is controlled to be P1.

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