Battery pack and method of manufacturing the same

Abstract

The application relates to a battery pack and a preparation method thereof. The battery pack comprises: a battery cell group, wherein the battery cell group comprises n battery cells connected in series; a positive electrode tab of an m-1th battery cell is connected with a negative electrode tab of an mth battery cell, and a negative electrode tab of a 1st battery cell is connected with a ground pin of a circuit board assembly; m and n are integers, n is greater than or equal to 2, and 1 is less than m and is less than or equal to n; the circuit board assembly comprises a voltage regulating circuit, and the voltage regulating circuit comprises a boosting element; and a first conductive piece, one end of the first conductive piece is connected with the boosting element in the circuit board assembly, and the other end of the first conductive piece is connected with a positive electrode tab of an nth battery cell in the battery cell group. Through direct connection of the first conductive piece with a small size, the current path of the low-voltage side of the voltage regulating circuit can be greatly shortened, the internal resistance on the current path is reduced, the heat loss on the path caused by the internal resistance is reduced, and the safety problem of the battery pack caused by heat generation is reduced.

Description

Technical Field

[0001] This application relates to the field of batteries, and in particular to a battery pack and a method for preparing the same. Background Technology

[0002] Battery packs are widely used in power tools, outdoor emergency power supplies, and smart mobile devices due to their portability. However, the safety of current battery packs still falls short of user needs, with several incidents of spontaneous combustion and fires occurring in products such as automobiles, robotic vacuum cleaners, and outdoor power supplies. Therefore, there is an urgent need for a battery pack with higher safety. Summary of the Invention

[0003] Therefore, it is necessary to provide a battery pack and its manufacturing method to address the safety issues of battery packs.

[0004] In a first aspect, this application provides a battery pack, comprising:

[0005] A circuit board assembly, the circuit board assembly including a voltage regulating circuit, the voltage regulating circuit including a boost element;

[0006] A battery cell assembly, comprising n battery cells connected in series; the positive electrode of the (m-1)th battery cell is connected to the negative electrode of the mth battery cell, and the negative electrode of the first battery cell is connected to the ground pin of the circuit board assembly; m and n are both integers, n≥2, 1<m≤n;

[0007] A first conductive element, one end of which is connected to a boost element in the circuit board assembly, and the other end of which is connected to the positive electrode tab of the nth cell in the cell group.

[0008] In one embodiment, the first conductive element has a stress relief region disposed between the end of the first conductive element for connecting the boost element and the end for connecting the positive electrode tab of the nth cell;

[0009] The stress relief zone includes at least one of a bend, a U-shaped groove, and a flexible braided section.

[0010] In one embodiment, the boost element includes a magnetic element, and the voltage regulating circuit further includes:

[0011] A switching unit, comprising an upper switching transistor and a lower switching transistor, wherein a first terminal of the lower switching transistor is grounded, a second terminal of the lower switching transistor is connected to the first terminal of the upper switching transistor, and a node between the upper and lower switching transistors is connected to one end of an inductor; at least one of the upper and lower switching transistors is a shielded gate trench MOSFET.

[0012] The other end of the magnetic element serves as the input terminal of the voltage regulating circuit, and the second end of the upper switching transistor serves as the output terminal of the voltage regulating circuit.

[0013] In one embodiment, the number of magnetic elements is two, and the number of switching units is also two, with the two magnetic elements respectively connected to the two switching units;

[0014] The magnetic element includes an inductor, and two inductors are wound in opposite phases on the same frame and share the same magnetic core to form a coupled inductor device.

[0015] In one embodiment, the battery pack further includes:

[0016] The second conductive component is used to connect the negative electrode tab of the first battery cell to the ground pin of the circuit board assembly.

[0017] The third conductive component is used to connect the positive electrode tab of the (m-1)th cell to the negative electrode tab of the mth cell.

[0018] In one embodiment, at least one of the first conductive element, the second conductive element, and the third conductive element includes a copper busbar, and at least one of the first conductive element, the second conductive element, and the third conductive element is connected by welding.

[0019] In one embodiment, the circuit board assembly further includes a controller, and the battery pack further includes:

[0020] A sampling module is positioned close to the third conductive component and connected to the controller in the circuit board assembly. The sampling module is used to collect cell information at its location and provide it to the controller.

[0021] In one embodiment, the battery pack includes two battery cells connected in series, the two battery cells are arranged along a first direction, and the positive electrode tab of one battery cell and the negative electrode tab of the other battery cell are arranged adjacent to each other in the first direction.

[0022] In one embodiment, the battery cell comprises a prismatic lithium iron phosphate cell.

[0023] Secondly, this application provides a method for preparing a battery pack, comprising:

[0024] A first conductive element is connected to one end of the boost element;

[0025] The other end of the boost element is connected to a printed circuit board to form a circuit board assembly;

[0026] Provide a battery cell assembly; the battery cell assembly includes n battery cells connected in series; the positive electrode tab of the (m-1)th battery cell is connected to the negative electrode tab of the mth battery cell; m and n are both integers, n≥2, 1<m≤n;

[0027] The other end of the first conductive element is connected to the positive electrode tab of the nth cell in the cell group, and the ground pin on the printed circuit board is connected to the negative electrode tab of the first cell in the cell group.

[0028] The aforementioned battery pack and its manufacturing method, by placing the positive electrode tab of the nth cell adjacent to the boost element and directly connecting it through a smaller first conductive element, can significantly shorten the current path on the low-voltage side of the voltage regulation circuit, thereby reducing the internal resistance on the current path, which in turn reduces the heat loss on the path caused by the internal resistance, and reduces the battery pack safety issues caused by heat generation. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is one of the top views of the battery pack according to an embodiment of this application;

[0031] Figure 2 One of the circuit diagrams of a voltage regulation circuit according to an embodiment;

[0032] Figure 3 One of the signal timing diagrams of a voltage regulation circuit according to an embodiment;

[0033] Figure 4 The second circuit diagram of a voltage regulation circuit is shown in one embodiment.

[0034] Figure 5 The second signal timing diagram of a voltage regulation circuit according to one embodiment;

[0035] Figure 6 The third signal timing diagram of a voltage regulation circuit according to one embodiment;

[0036] Figure 7 This is a second top view of the battery pack according to an embodiment of this application;

[0037] Figure 8 This is a flowchart illustrating a method for preparing a battery pack according to one embodiment.

[0038] Component designation explanation:

[0039] Battery cell assembly: 100; Battery cell: 110; Positive electrode tab: 111; Negative electrode tab: 112; Circuit board assembly: 200; Boost element: 210; First conductive element: 310; Stress relief zone: 311; Second conductive element: 320; Third conductive element: 330; Sampling module: 410; First connector: 510; Second connector: 520. Detailed Implementation

[0040] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0042] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0043] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0044] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0045] When used herein, the singular forms of “a,” “an,” and “ / the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0046] This application provides a battery pack that can be used to power a device. The device can be a medium-power device, defined as a device with a power rating between 200W and 1000W, including but not limited to motors, heat-generating devices, and lighting devices. It should be noted that the battery pack can also power low-power devices; this is not a limitation.

[0047] Based on the electrical relationship P=U*I, if a low voltage of 12V or less is used to power a medium-power device, the supply current must be significantly increased to maintain the same power. However, higher current requires thicker wires, larger current-carrying devices, and stronger heat dissipation, resulting in increased device size and a significant increase in overall cost. Furthermore, it is understood that the loss of the power supply signal in the current path is the product of the square of the current and the internal resistance. Taking an output power of 600W and an internal resistance of 5mΩ as an example, if a 48V voltage is used to provide the power supply signal, the loss in the path is only about 0.78W. However, if a 6.4V voltage is used, the loss in the path is about 43.95W. Therefore, in the consumer field, a medium voltage of 36V to 60V can be used for power supply, and the internal resistance in the current path can be systematically reduced through the embodiments of this application, thereby further reducing the loss in the current path and enabling medium-power devices to achieve higher power density.

[0048] Figure 1 This is one of the top view schematic diagrams of the battery pack according to an embodiment of this application. A top view schematic diagram refers to a schematic diagram obtained along the top direction with reference to the placement of the battery pack during normal use. (Reference) Figure 1 The battery pack includes a cell assembly 100, a circuit board assembly 200, a first conductor, and a second conductor. The battery pack may also include a housing, which may be made of materials such as aluminum alloy, galvanized steel sheet, or stainless steel. The cell assembly 100, circuit board assembly 200, first conductor, and second conductor can be encapsulated within the battery pack housing to provide mechanical protection for these structures. The housing may have connection terminals for connecting to the device to be powered. These connection terminals connect inward to the circuit board assembly 200, thereby providing the target power supply signal processed by the circuit board assembly 200 to the device to be powered via the connection terminals.

[0049] The battery cell assembly 100 comprises n battery cells 110 connected in series. The positive electrode tab 111 of the (m-1)th battery cell 110 is connected to the negative electrode tab 112 of the mth battery cell 110. The negative electrode tab 112 of the first battery cell 110 is led out as the negative electrode tab 112 of the entire battery cell assembly 100, and the positive electrode tab 111 of the nth battery cell 110 is led out as the positive electrode tab 111 of the entire battery cell assembly 100. m and n are both integers, n≥2, 1<m≤n.

[0050] For example, if n=2, the negative electrode tab 112 of the first cell 110 is led out as the negative electrode tab of the entire cell group 100, the positive electrode tab 111 of the first cell 110 is connected to the negative electrode tab 112 of the second cell 110, and the positive electrode tab 111 of the second cell 110 is led out as the positive electrode tab of the entire cell group 100. In another example, if n=3, the negative electrode tab 112 of the first cell 110 is led out as the negative electrode tab of the entire cell group 100. The positive electrode tab 111 of the first cell 110 is connected to the negative electrode tab 112 of the second cell 110. The positive electrode tab 111 of the second cell 110 is connected to the negative electrode tab 112 of the third cell 110. The positive electrode tab 111 of the third cell 110 is led out as the positive electrode tab of the entire cell group 100. Based on this, this embodiment does not limit the number of cells 110 in the cell group 100. The specific number can be determined based on the output requirements of the cell group 100, the capacity and output capability of a single cell 110, and the wiring requirements in the cell group 100.

[0051] Furthermore, cell 110 can be a lithium iron phosphate cell 110. Because lithium iron phosphate crystals have an olivine structure, the skeleton is less prone to collapse under conditions such as high temperature, overcharge, and compression, resulting in high stability. Therefore, it is suitable for achieving larger capacity cells 110. The capacity of a single lithium iron phosphate cell 110 can reach 300Wh to 1000Wh. When the device to be powered is a medium-power device, cell group 100 consisting of two cells 110 connected in series is sufficient to meet the requirements. Furthermore, the lithium iron phosphate cell 110 can be a square lithium iron phosphate cell 110, thus facilitating assembly and integration design.

[0052] The circuit board assembly 200 refers to a printed circuit board with soldered electrical components. In this embodiment, the circuit board assembly 200 can be understood as a battery management system (BMS) motherboard including a voltage regulating circuit. In addition to the voltage regulating circuit, the circuit board assembly 200 may further include a controller. The controller is used to process and analyze the sampled information of the battery cell 110, and to implement conventional power supply control functions based on the information of the battery cell 110, as well as protection control functions in scenarios such as overvoltage, undervoltage, overcurrent, short circuit, and overtemperature.

[0053] Furthermore, the voltage regulating circuit includes a boost element 210, which includes, but is not limited to, an inductor. The voltage regulating circuit can regulate the initial power supply signal output from the battery pack 100 and provide a target power supply signal that meets the power supply requirements of the device to be powered. The voltage regulation process performed by the voltage regulating circuit includes at least one of boost processing and buck processing. For example, the voltage regulating circuit can use boost processing to convert the initial power supply signal into a target power supply signal of 36V to 60V to meet the power supply requirements of medium-power devices. As another example, the voltage regulating circuit can use buck processing to convert the initial power supply signal into a target power supply signal of 5V to 12V to meet the power supply requirements of low-power devices.

[0054] One end of the first conductive element 310 is connected to the boost element 210 in the circuit board assembly 200, and the other end of the first conductive element 310 is exposed in the circuit board assembly 200, so that the other end of the first conductive element 310 can be connected to the positive electrode tab 111 of the nth cell 110 in the cell group 100. The first conductive element 310 may include, but is not limited to, any of the following: rigid copper busbar, flexible copper busbar, copper-aluminum composite busbar, etc.

[0055] In the embodiments of the application, by placing the positive electrode tab 111 of the nth cell 110 adjacent to the boost element 210 and directly connecting it through the smaller first conductive element 310, the current path on the low-voltage side of the voltage regulation circuit can be significantly shortened, thereby reducing the internal resistance on the current path, thereby reducing the heat loss on the path caused by the internal resistance, and reducing the battery pack safety issues caused by heat generation.

[0056] In some embodiments, the first conductive element 310 has a stress relief region 311. The stress relief region 311 is disposed between the end of the first conductive element 310 used to connect to the boost element 210 and the end used to connect to the positive electrode tab 111 of the nth cell 110. Specifically, as the number of charge and discharge cycles of the battery pack increases, the cell 110 may expand or deform to a certain extent, causing stress problems in the circuit board assembly 200. In this embodiment, by providing the stress relief region 311 of the first conductive element 310, the stress impact of the expansion or deformation of the cell 110 on the circuit board assembly 200 can be buffered, thereby ensuring the stability and reliability of the circuit board assembly 200. Further, the stress relief region 311 includes at least one of a bending portion, a U-shaped groove, and a flexible braided section.

[0057] Figure 2 One of the circuit diagrams of a voltage regulation circuit according to an embodiment, see reference. Figure 2In some embodiments, the boost element includes a magnetic element, and the voltage regulating circuit further includes a switching unit. The switching unit includes an upper switching transistor and a lower switching transistor. The first terminal of the lower switching transistor is grounded, and the second terminal of the lower switching transistor is connected to the first terminal of the upper switching transistor. The node between the upper and lower switching transistors is connected to one end of the magnetic element. The other end of the magnetic element serves as the input terminal of the voltage regulating circuit, and the second terminal of the upper switching transistor serves as the output terminal of the voltage regulating circuit. The magnetic element includes, but is not limited to, inductors and transformers.

[0058] In this circuit, at least one of the upper and lower switching transistors can be a shielded-gate trench MOSFET (SGT-MOS). The SGT-MOS transistor has two polysilicon sections within its trench, forming the upper gate and lower shielding gate respectively, isolated by a thick oxide layer. The trench depth is 3 to 5 times that of conventional processes. Therefore, in low-to-medium voltage, high-current scenarios, the SGT-MOS transistor can achieve superior performance in both conduction and switching losses. Furthermore, the voltage regulation circuit also includes an input capacitor connected to the input terminal of the voltage regulation circuit and an output capacitor connected to the output terminal of the voltage regulation circuit to maintain the stability of the input and output signals of the voltage regulation circuit.

[0059] Based on the circuit structure of the voltage regulation circuit described above, it can be determined according to, as follows: Figure 3 The timing diagram illustrates the control of the voltage regulator circuit. Taking an inductor as an example, specifically, during time period T1, the lower switch MOS1 is turned on, and the upper switch MOS2 is turned off, applying the input voltage across the inductor and storing energy. During time period T2, the lower switch MOS1 is turned off, and the upper switch MOS2 is turned on, allowing the inductor to freewheel through MOS2 and release its stored energy. Therefore, the output voltage of the voltage regulator circuit can be changed by adjusting the duty cycle of the timing control signals for the lower and upper switches MOS1 and MOS2. That is, extending T1 or shortening T2 increases the duty cycle, thereby increasing the output voltage of the voltage regulator circuit; shortening T1 or extending T2 decreases the duty cycle, thereby decreasing the output voltage of the voltage regulator circuit.

[0060] In this embodiment, a non-isolated half-bridge topology is used. This design offers a simple circuit, fast response, and low cost. Compared to traditional high-ratio circuit topologies such as CLLC / DAB, isolated high-ratio topologies are more complex, more expensive, and require higher static power consumption to maintain stable voltage output, potentially resulting in standby power consumption exceeding 10W. Furthermore, isolated high-ratio topologies exhibit poor bidirectional dynamic response and slow charge / discharge switching time, making them unsuitable for implementing kinetic energy recovery functions in motor-type load devices.

[0061] Understandably, at low temperatures, the viscosity of the electrolyte in cell 110 increases, making it difficult for lithium ions to migrate. This leads to an increase in the internal resistance of cell 110, a decrease in output power, and may even cause lithium plating, significantly impacting the lifespan and safety of cell 110. In some embodiments, based on the high-response characteristics of the voltage regulation circuit, the output capacitor can be charged first, and then the output capacitor can be used to charge cell 110, achieving rapid charging and discharging of cell 110 and injecting high-frequency AC current into cell 110. During the rapid charging and discharging process of cell 110, cell 110 does not have time to polarize and will heat up according to the ACR*I*I heating power. Moreover, the above heating process has minimal impact on the lifespan of cell 110. Therefore, this embodiment can achieve non-destructive self-heating of cell 110 through rapid charging and discharging, thereby reducing the impact of low-temperature environment on battery pack performance and ensuring the output power and safety of the battery pack.

[0062] Furthermore, the higher the charge / discharge frequency of cell 110, the higher its area-specific resistance (ACR) response. Therefore, during charging, the charge / discharge rate can be adjusted according to the charging window of cell 110. For example, if the ambient temperature of the battery pack is 5°C, then it can only be charged slowly at 0.2C to allow sufficient time for lithium-ion diffusion and embedding in graphite, thus avoiding lithium plating. Based on this, it can be discharged at 0.5C and charged at 0.7C, achieving both 0.5C AC self-heating and 0.2C charging, i.e., charging and heating simultaneously. This allows for higher charging rates after the cell 110 temperature rises to a safe range, improving the charging efficiency of the battery pack.

[0063] Furthermore, high-specification printed circuit boards (PCBs) in the industry currently typically use a 2oz copper thickness design. Under a temperature rise control of 40℃, a surface copper foil width of approximately 60mm is sufficient to meet current carrying requirements, while the inner copper foil requires approximately 260mm. Considering the current common use of 10mm×11.5mm toll packages for medium-voltage high-power MOSFETs and the conventional PCB structure design with surface traces and inner layers serving as ground plane references, the current carrying capacity of a single conventional PCB is close to the process limit at around 100A. Moreover, due to the presence of high-frequency ripple current in circuits, the skin effect and proximity effect further increase conductor AC losses, resulting in a typical safe current carrying capacity of only 50A to 100A for conventional PCBs. Further increasing current carrying capacity requires the use of special materials such as 3oz or larger copper foil, copper substrates, or aluminum substrates, leading to a sharp increase in PCB costs and making it difficult to meet the design requirements for low cost and high power density in medium-voltage high-power applications.

[0064] To address the aforementioned issues, in some embodiments, the number of magnetic elements and switching units is multiple, with each magnetic element connected to a corresponding switching unit. The number of magnetic elements is the same as the number of switching units, for example, two, three, or four, depending on requirements. In this embodiment, the magnetic elements include inductors. Figure 4 This is a second circuit diagram of a voltage regulation circuit according to one embodiment, see reference. Figure 4 The voltage regulation circuit shown includes two inductors and two switching units. By increasing the number of phases, this embodiment can spread the large current of a single path, effectively increasing the current limit of the voltage regulation circuit without the need for special materials such as copper foil, copper substrate or aluminum substrate of 3oz or above, thus ensuring the cost controllability of the battery pack.

[0065] In some embodiments, taking an example where there are two inductors and two switching units, based on... Figure 4 The voltage regulation circuit in the embodiment can be based on, for example... Figure 5 The timing sequence shown controls the voltage regulation circuit. Specifically, during time period T1, the lower switches MOS1 and MOS3 are turned on, while the upper switches MOS2 and MOS4 are turned off. The input voltage is applied to the inductor terminals, and the inductor stores energy. During time period T2, the lower switches MOS1 and MOS3 are turned off, while the upper switches MOS2 and MOS4 are turned on. The inductor freewheels through the upper switches MOS2 and MOS4, releasing the stored energy. Therefore, the output voltage of the voltage regulation circuit can be changed by adjusting the duty cycle of the timing control signals for the lower switches MOS1 and MOS3 and the upper switches MOS2 and MOS4. That is, extending T1 or shortening T2 increases the duty cycle, thereby increasing the output voltage of the voltage regulation circuit; shortening T1 or extending T2 decreases the duty cycle, thereby decreasing the output voltage of the voltage regulation circuit.

[0066] In some embodiments, based on Figure 4 The voltage regulation circuit of this embodiment, taking two inductors and two switching units as an example, can be based on, as follows: Figure 6The timing diagram illustrates the control of the voltage regulation circuit. For ease of explanation, the branch containing the lower switch MOS1 and the upper switch MOS2 is referred to as branch 1, and the branch containing the lower switch MOS3 and the upper switch MOS4 is referred to as branch 2. Specifically, during time period T0.5, the lower switch MOS1 and the upper switch MOS4 are turned on, while the upper switch MOS2 and the lower switch MOS3 are turned off. The inductor corresponding to branch 1 stores energy, and the inductor corresponding to branch 2 releases the stored energy. At this time, the current changes in the multiple paths have opposite trends, and the input current ripple cancels each other out. During time period T1, the upper switch MOS2 and the upper switch MOS4 are turned on, while the lower switch MOS1 and the lower switch MOS3 are turned off. The inductors in multiple branches release the stored energy together to ensure the continuity of the output voltage. During time period T1.5, the upper switch MOS2 and the lower switch MOS3 are turned on, while the lower switch MOS1 and the upper switch MOS4 are turned off. The inductor corresponding to branch 1 releases its stored energy, while the inductor corresponding to branch 2 stores energy. At this time, the current changes in the multiple paths are opposite, and the input current ripple cancels each other out. During time period T2, the upper switch MOS2 and the upper switch MOS4 are turned on, while the lower switch MOS1 and the lower switch MOS3 are turned off. The inductors of multiple branches release their stored energy together to ensure the continuity of the output voltage. Therefore, in this embodiment, the two branches operate alternately by 180°, which can effectively cancel the current ripple of the voltage regulation circuit output signal. Stable output can be achieved with a smaller output capacitor, thereby reducing the output capacitor by more than 50%.

[0067] In some embodiments, two inductors are wound in opposite phases on the same frame and share the same magnetic core to form a coupled inductor device. By winding the two interleaved inductors in opposite phases, the operating currents of the two inductors are 180° out of phase, and the alternating magnetic flux generated in the magnetic core is in opposite directions and has similar amplitude. Therefore, the magnetic flux can be significantly canceled, and the AC magnetic flux swing of the magnetic core can be significantly reduced. Compared with the traditional discrete uncoupled inductor scheme, the coupled inductor structure of the present invention can reduce the magnetic core magnetic loss by 80% to 90%, while significantly reducing the size and weight of the inductor and reducing the device cost. The two inductors can be connected to the same first conductive element 310, for example, to the same copper busbar.

[0068] In some embodiments, the cell assembly 100 further includes at least one of a second conductive element 320 and a third conductive element 330. The second conductive element 320 is used to connect the negative electrode tab 112 of the first cell 110 to the ground pin of the circuit board assembly 200. The third conductive element 330 is used to connect the positive electrode tab 111 of the (m-1)th cell 110 to the negative electrode tab 112 of the m-th cell 110. Therefore, when the number of cells 110 in the cell assembly 100 is three or more, the number of third conductive elements 330 can also be multiple.

[0069] In some embodiments, at least one of the first conductive element 310, the second conductive element 320, and the third conductive element 330 includes a copper busbar. The copper busbar includes, but is not limited to, any of the following: rigid copper busbar, flexible copper busbar, copper-aluminum composite busbar, etc. The copper busbar has low AC and DC resistance, thereby effectively reducing losses in high-current paths. Especially in the medium-voltage, high-power application scenarios of this application, using a copper busbar to connect the battery cell 110 to the inductor can control losses in the path to an extremely low level, thereby avoiding loss problems caused by traditional wiring methods and improving the output efficiency of the voltage regulation circuit.

[0070] In some embodiments, at least one of the first conductive element 310, the second conductive element 320, and the third conductive element 330 is connected by welding. It is understood that interconnecting the conductive elements with the circuit board assembly 200 or the battery cell 110 tabs using bolts or pluggable high-power connectors results in poor manufacturability and reliability, as well as high cost. Furthermore, if the bolts or connectors are not properly secured during assembly, or if they loosen during use, serious problems such as open circuits or even overheating and burning can easily occur. Therefore, this embodiment uses welding for connection, which keeps the contact resistance at the connection point within a stable low range and eliminates the need to reserve positions for bolts or connectors, facilitating a more compact battery pack design.

[0071] Figure 7 This is a second top view schematic diagram of the battery pack according to an embodiment of this application, with reference to... Figure 7 In some embodiments, the circuit board assembly 200 further includes a controller, and the battery pack further includes a sampling module 410. The sampling module 410 is positioned close to the third conductive element 330 and connected to the controller in the circuit board assembly 200. The sampling module 410 is used to collect information about the battery cells 110 at its location and provide it to the controller. The information collected by the sampling module 410 about the battery cells 110 includes, but is not limited to, voltage, current, and temperature information. By setting up the sampling module 410, the operating status of the battery cell assembly 100 can be monitored in real time and adaptively adjusted, thereby ensuring that the battery cell assembly 100 is in a stable and reliable operating state. Furthermore, the sampling module 410 can be connected to the circuit board assembly 200 via a first connector 510, thereby facilitating maintenance and replacement of the sampling module 410.

[0072] In some embodiments, the cell pack 100 includes two cells 110 connected in series. The fewer cells in the cell pack 100, the simpler and safer the battery pack system. Furthermore, using large-capacity individual cells 110 simplifies the battery pack's protective structure, resulting in a smaller overall battery pack size. Further, the two cells 110 are arranged along a first direction, with the positive electrode tab 111 of one cell 110 and the negative electrode tab 112 of the other cell 110 adjacent to each other in the first direction. It is understood that traditional 48V battery systems often use 14- or 16-cell lithium iron phosphate batteries. In this multi-cell series arrangement, the cell 110 located in the middle of the module is surrounded by other cells 110, resulting in poor heat dissipation and a tendency to operate at higher temperatures for extended periods. Conversely, the cells 110 located at the edge of the module have better heat dissipation and operate at relatively lower temperatures for longer periods. The temperature difference of the aforementioned cells 110 can easily degrade the consistency of capacity and internal resistance among different cells 110, leading to uneven charging and discharging of the cells 110. This necessitates the configuration of passive or active balancing circuits. Balancing circuits not only increase system heat generation, occupy installation space, and raise hardware costs, but also prolong the overall charging time and adversely affect the accurate calculation of the remaining battery pack capacity. Therefore, this embodiment adopts a symmetrical layout of dual cells 110, which effectively avoids the formation of localized thermal centers within the battery pack, thus reducing the likelihood of inconsistent degradation of the cells 110. This eliminates the need for balancing circuits and facilitates a more compact battery pack design.

[0073] In some embodiments, the battery pack further includes a communication module, and the circuit board assembly 200 further includes a second connector 520 for connecting to the communication module. The communication module can send information such as the aforementioned cell 110 to external devices, and can also receive control signals from external devices and adjust the operating state of the battery pack in response to the control signals.

[0074] This application also provides a method for preparing a battery pack. Figure 8 This is a flowchart of a method for preparing a battery pack according to an embodiment, with reference to... Figure 8 The battery pack preparation method includes steps 802 to 808.

[0075] Step 802: Connect the first conductive element 310 to one end of the boost element 210.

[0076] Step 804: Connect the other end of the boost element 210 to the printed circuit board to form the circuit board assembly 200.

[0077] Step 806: Provide battery cell assembly 100.

[0078] The battery cell assembly 100 comprises n battery cells 110 connected in series. The positive electrode tab 111 of the (m-1)th battery cell 110 is connected to the negative electrode tab 112 of the m-th battery cell 110. m and n are both integers, n ≥ 2, 1 < m ≤ n;

[0079] Step 808: Connect the other end of the first conductive element 310 to the positive electrode tab 111 of the nth cell 110 in the cell group 100, and connect the ground pin on the printed circuit board to the negative electrode tab 112 of the first cell 110 in the cell group 100.

[0080] In this embodiment, the boost element 210, the first conductive element 310, the second conductive element 320, and the printed circuit board are first prefabricated into an integrated circuit board assembly 200, which is then uniformly connected to the cell assembly 100 to achieve modular assembly. This facilitates automated production and improves assembly consistency and production efficiency. By placing the positive electrode tab 111 of the nth cell 110 adjacent to the boost element 210 and directly connecting it through the smaller first conductive element 310, the current path on the low-voltage side of the voltage regulation circuit can be significantly shortened, thereby reducing the internal resistance on the current path. This reduces heat loss on the path caused by internal resistance and minimizes battery pack safety issues caused by heat generation.

[0081] In some embodiments, one end of the second conductive element 320 may be connected to a ground pin on a printed circuit board in step 802, and the other end of the second conductive element 320 may be connected to the negative electrode tab 112 of the first cell 110 in the cell group 100 in step 808.

[0082] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0083] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0084] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A battery pack, characterized in that, include: A circuit board assembly, the circuit board assembly including a voltage regulating circuit, the voltage regulating circuit including a boost element; A battery cell assembly, comprising n battery cells connected in series; the positive electrode of the (m-1)th battery cell is connected to the negative electrode of the mth battery cell, and the negative electrode of the first battery cell is connected to the ground pin of the circuit board assembly; m and n are both integers, n≥2, 1<m≤n; A first conductive element, one end of which is connected to a boost element in the circuit board assembly, and the other end of which is connected to the positive electrode tab of the nth cell in the cell group.

2. The battery pack according to claim 1, characterized in that, The first conductive element has a stress relief region, which is located between the end of the first conductive element used to connect the boost element and the end used to connect the positive electrode tab of the nth cell. The stress relief zone includes at least one of a bend, a U-shaped groove, and a flexible braided section.

3. The battery pack according to claim 1, characterized in that, The boost element includes a magnetic element, and the voltage regulating circuit further includes: A switching unit, comprising an upper switching transistor and a lower switching transistor, wherein the first terminal of the lower switching transistor is grounded, the second terminal of the lower switching transistor is connected to the first terminal of the upper switching transistor, and the node between the upper and lower switching transistors is connected to one end of the magnetic element; at least one of the upper and lower switching transistors is a shielded gate trench MOSFET. The other end of the magnetic element serves as the input terminal of the voltage regulating circuit, and the second end of the upper switching transistor serves as the output terminal of the voltage regulating circuit.

4. The battery pack according to claim 3, characterized in that, The number of magnetic elements is two, and the number of switching units is also two, with the two magnetic elements respectively connected to the two switching units; The magnetic element includes an inductor, and two inductors are wound in opposite phases on the same frame and share the same magnetic core to form a coupled inductor device.

5. The battery pack according to any one of claims 1 to 4, characterized in that, The battery cell assembly also includes: The second conductive component is used to connect the negative electrode tab of the first battery cell to the ground pin of the circuit board assembly. The third conductive component is used to connect the positive electrode tab of the (m-1)th cell to the negative electrode tab of the mth cell.

6. The battery pack according to claim 5, characterized in that, At least one of the first conductive element, the second conductive element, and the third conductive element includes a copper busbar, and at least one of the first conductive element, the second conductive element, and the third conductive element is connected by welding.

7. The battery pack according to claim 5, characterized in that, The circuit board assembly also includes a controller, and the battery pack also includes: A sampling module is positioned close to the third conductive component and connected to the controller in the circuit board assembly. The sampling module is used to collect cell information at its location and provide it to the controller.

8. The battery pack according to claim 1, characterized in that, The battery cell assembly includes two battery cells connected in series, the two battery cells are arranged along a first direction, and the positive electrode tab of one battery cell and the negative electrode tab of the other battery cell are arranged adjacent to each other in the first direction.

9. The battery pack according to claim 1, characterized in that, The battery cell includes a square lithium iron phosphate battery cell.

10. A method for preparing a battery pack, characterized in that, include: A first conductive element is connected to one end of the boost element; The other end of the boost element is connected to a printed circuit board to form a circuit board assembly; Provide battery packs; The battery cell assembly includes n battery cells connected in series; the positive electrode tab of the (m-1)th battery cell is connected to the negative electrode tab of the mth battery cell; m and n are both integers, n≥2, 1<m≤n; The other end of the first conductive element is connected to the positive electrode tab of the nth cell in the cell group, and the ground pin on the printed circuit board is connected to the negative electrode tab of the first cell in the cell group.

Images