Battery pack and battery pack voltage balancing method

Abstract

The present application discloses a battery pack and a battery pack voltage balancing method. The battery pack comprises: a plurality of cell units; a voltage balancing circuit electrically connected to a cell assembly and configured to balance voltages of the cell units; and a power management device electrically connected to the cell assembly to acquire the voltages of the cell units, the power management device being further configured to be at least connected to the voltage balancing circuit, so as to balance the voltages of the cell units in a balancing mode. In the balancing mode, the power management device is configured to: output, on the basis of the acquired voltages of the cell units, serial numbers of cell units that require voltage balancing; and calculate the maximum voltage sum of non-adjacent cell units among the cell units corresponding to the serial numbers, and control the voltage balancing circuit to balance voltages of the cell units corresponding to the maximum voltage sum. The present application provides a battery pack having higher balancing efficiency and a better balancing effect, and a battery pack voltage balancing method.

Description

Battery pack and battery pack voltage balancing methods

[0001] This application claims priority to Chinese Patent Application No. 202411924899.6, filed with the Chinese Patent Office on December 25, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to a battery pack, specifically a method for voltage equalization of a battery pack. Background Technology

[0003] To extend battery pack life and improve battery pack performance, battery pack balancing is typically performed when the battery pack is fully charged or at rest. One related technology involves passively balancing battery packs by periodically switching between odd and even cell positions during voltage balancing. Specifically, for the selected cell positions to be balanced, the odd-numbered cell positions are balanced first. After balancing the odd-numbered cell positions for a period, the system switches to balancing the even-numbered cell positions. This process is repeated, with the odd-numbered cell positions being switched back to balancing after a period of time.

[0004] This section provides background information related to this application, which is not necessarily prior art. Summary of the Invention

[0005] One objective of this application is to solve or at least alleviate some or all of the aforementioned problems. Therefore, one objective of this application is to provide a battery pack and a battery pack voltage balancing method with higher balancing efficiency and better balancing effect.

[0006] To achieve the above objectives, this application adopts the following technical solution: A battery pack includes: a cell assembly comprising multiple cell units, providing discharge current to power power tools; a voltage equalization circuit electrically connected to the cell assembly for equalizing the voltage of each cell unit; a power management device electrically connected to the cell assembly to acquire the voltage of each cell unit; the power management device is connected to the voltage equalization circuit and performs voltage equalization on the multiple cell units based on the voltage equalization circuit; the power management device is configured to acquire the voltage of each cell unit; determine the cell unit number that needs to be voltage equalized based on the acquired voltages, and estimate the sum of the maximum voltages of the non-adjacent cell units corresponding to the cell unit number; and control the voltage equalization circuit to perform voltage equalization on the cell unit corresponding to the maximum voltage sum.

[0007] In some embodiments, the power management device further includes an equalization judgment unit, which is configured to control the battery pack to operate in a voltage equalization mode when the voltage difference between the maximum and minimum voltage values ​​of each cell cell is greater than a first voltage threshold.

[0008] In some embodiments, the equalization judgment unit is configured to control the battery pack to exit the equalization mode when the voltage difference between the maximum and minimum voltage values ​​of each cell is less than or equal to a first voltage threshold.

[0009] In some embodiments, the power management device is configured to acquire the voltage of each battery cell, and when the voltage difference between the voltage and the minimum voltage value is greater than a first voltage threshold, the power management device marks the corresponding battery cell as a battery cell that needs to be voltage balanced.

[0010] In some embodiments, the first voltage threshold is essentially set to 100mV.

[0011] In some embodiments, the power management device further includes an analog front-end chip for acquiring the voltage of each battery cell.

[0012] In some embodiments, the analog front-end chip is connected to the voltage equalization circuit to control the operation of the voltage equalization circuit.

[0013] In some embodiments, the power management device further includes a controller, which is used at least to manage the charging and discharging state of the battery pack.

[0014] In some embodiments, the analog front-end chip is configured to be woken up by a button or external communication, and the controller is woken up and powered on by the analog front-end chip.

[0015] In some embodiments, the controller sends a deep sleep command to the analog front-end chip to enter deep sleep mode. Upon receiving the command, the analog front-end chip shuts off its power supply output to power down the controller.

[0016] In some embodiments, the voltage equalization circuit includes resistors connected to each battery cell.

[0017] In some embodiments, the rated voltage of the battery pack is greater than or equal to 24V and less than or equal to 80V.

[0018] In some embodiments, the battery pack further includes a terminal assembly, which includes electrode terminals that can be electrically connected to a power tool.

[0019] In some embodiments, the battery pack further includes a housing that forms or is connected to a connection guide that guides the electrode terminals to be electrically connected to a power tool.

[0020] One embodiment of this application also discloses a voltage balancing method for a battery pack, which obtains the voltage of each cell unit of the battery pack;

[0021] Based on the obtained voltage, determine the cell number that needs to be voltage balanced; calculate the sum of the maximum voltages of the non-adjacent cell numbers corresponding to the cell number; and perform voltage balancing operation on the cell number corresponding to the sum of the maximum voltages.

[0022] In some embodiments, the maximum and minimum voltage values ​​of each cell are obtained, and when the voltage difference between the maximum and minimum values ​​is greater than a first voltage threshold, the battery pack is controlled to operate in voltage equalization mode.

[0023] In some embodiments, when the voltage difference between the maximum and minimum values ​​is less than or equal to a first voltage threshold, the battery pack is controlled to exit the voltage equalization mode.

[0024] In some embodiments, the voltage of each cell is obtained, and when the voltage difference between the voltage and the minimum voltage value is greater than a first voltage threshold, the corresponding cell is marked as a cell that needs to be voltage balanced. Attached Figure Description

[0025] Figure 1 is a schematic diagram of a connection between a battery pack and a power tool according to an embodiment of this application;

[0026] Figure 2 is a schematic diagram of a battery pack according to an embodiment of this application;

[0027] Figure 3 is a schematic diagram of the exploded structure of the battery pack in Figure 2;

[0028] Figure 4 is a structural diagram of a battery pack according to an embodiment of this application;

[0029] Figure 5 is a comparison of the sampled voltage data of the voltage equalization method of this application and the voltage equalization method of related technologies;

[0030] Figure 6 is a structural diagram of another battery pack provided according to an embodiment of this application;

[0031] Figure 7 is a flowchart of a voltage equalization method for a battery pack according to an embodiment of this application;

[0032] Figure 8 is a flowchart of another battery pack voltage equalization method provided according to an embodiment of this application;

[0033] Figure 9 is a flowchart of another battery pack voltage equalization method provided according to an embodiment of this application. Detailed Implementation

[0034] Before explaining any implementation of this application in detail, it should be understood that this application is not limited to its application to the structural details and component arrangements set forth in the following description or shown in the above drawings.

[0035] In this application, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0036] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "and / or" relationship.

[0037] In this application, the terms "connection," "combination," "coupling," and "installation" can refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without the need for an intermediary, while an indirect connection refers to two parts or components each being connected to at least one intermediary, with the connection achieved through the intermediary. Furthermore, "connection" and "coupling" are not limited to physical or mechanical connections or couplings, but can also include electrical connections or couplings.

[0038] In this application, those skilled in the art will understand that relative terms (e.g., “about,” “approximately,” “basically,” etc.) used in conjunction with quantities or conditions are to include the values ​​and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances associated with the particular value due to manufacturing, assembly, use, etc. Such terms should also be considered as disclosing a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​not using relative terms should also be disclosed as specific values ​​with tolerances. Furthermore, “basically” when expressing relative angular relationships (e.g., substantially parallel, substantially perpendicular) may refer to a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) added to or subtracted from the indicated angle.

[0039] In this application, those skilled in the art will understand that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0040] In this application, the directional terms "upper," "lower," "left," "right," "front," and "rear" are used to describe the orientation and positional relationships shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when an element is mentioned as being connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element. It should also be understood that directional terms such as upper side, lower side, left side, right side, front side, and rear side not only represent positive orientation but can also be understood as lateral orientation. For example, "below" can include directly below, lower left, lower right, lower front, and lower rear.

[0041] In this application, the terms "controller," "processor," "central processing unit," "CPU," and "MCU" are used interchangeably. When using the unit "controller," "processor," "central processing unit," "CPU," or "MCU" to perform a specific function, unless otherwise stated, these functions may be performed by a single or multiple of the aforementioned units.

[0042] In this application, the terms "device," "module," or "unit" are used to describe devices that can be implemented in hardware or software to perform a specific function.

[0043] In this application, the terms “calculation,” “judgment,” “control,” “determine,” “identify,” etc., refer to the operation and process of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0044] The benefits, other advantages, and solutions to problems will be described below with reference to specific embodiments. However, these benefits, advantages, solutions to problems, and any features that may lead to or make any benefit, advantage, or solution appear or become more significant should not be construed as key, necessary, or essential features of any or all claims.

[0045] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] As shown in Figures 1 and 2, this embodiment of the application illustrates a battery pack 30, which is detachably connected to a power tool 20 to supply power to the power tool 20. The power tool 20 can be a vegetation care tool, such as a lawnmower, lawn trimmer, pruning machine, chainsaw, etc. Alternatively, the power tool 20 can be a cleaning tool, such as a hair dryer, snowplow, washing machine, etc. Alternatively, the power tool 20 can be a drilling tool, such as a drill, screwdriver, wrench, hammer drill, etc. Alternatively, the power tool 20 can be a sawing tool, such as a reciprocating saw, jigsaw, circular saw, etc. Alternatively, the power tool 20 can be a bench saw, such as a table saw, miter saw, metal cutter, bakelite milling machine, etc. Alternatively, the power tool 20 can be a grinding tool, such as an angle grinder, sander, etc. In this embodiment, the power tool 20 is specifically an impact wrench. The following description uses an impact wrench as an example to illustrate the technical solution of this application, but this should not be construed as limiting the application. The battery pack 30 also includes a terminal assembly comprising electrode terminals that can be electrically connected to a power tool. The battery pack 30 also includes a housing 31, which forms or is connected to a connection guide portion that guides the electrode terminals to electrically connect to the power tool.

[0047] In some embodiments, the battery pack 30 includes, but is not limited to, a lithium iron phosphate battery pack, a lithium battery pack, and a multi-tab battery pack. In some embodiments, the rated voltage or nominal voltage of the battery pack 30 is greater than or equal to 24V and less than or equal to 80V. For example, the rated voltage or nominal voltage of the battery pack 30 may be 36V, 40V, 48V, or 56V.

[0048] As shown in Figures 2 and 3, the battery pack 30 includes a housing 31 and a cell assembly 32 located within the housing 31. The housing 31 is assembled to form a receiving space to fix and house the cell assembly 32. The cell assembly 32 includes one or more cell units 321, which are used to store or output electrical energy. Multiple cell units 321 are connected in series, parallel, or a combination of series and parallel to form the cell assembly 32. The multiple cell units 321 are at least used to provide discharge current to power the power tool 20. That is, when the power tool 20 needs electrical energy to drive its motor or other components, the cell units 321 in the cell assembly 32 will start to discharge. The electrical energy released by the cell units 321 is transferred to the power tool 20 through an external circuit to provide it with the required current.

[0049] As shown in Figure 4, the battery pack 30 also includes a voltage equalization circuit 33, which is electrically connected to the cell assembly 32 and used to equalize the voltage of each cell unit 321. The voltage equalization circuit 33 is used to adjust the voltage differences between the individual cell units 321 in the battery pack 30, ensuring they maintain a relatively consistent voltage level. During the use of the battery pack 30, due to various factors, the voltage of each cell unit 321 may gradually deviate. The voltage equalization circuit 33 takes appropriate measures to reduce or eliminate these differences, thereby extending the service life of the battery pack 30 and improving the reliability and safety of the system.

[0050] In some embodiments, the voltage equalization circuit 33 includes a resistor 331 connected to each battery cell 321 to dissipate excess energy in the battery cell 321 when needed. In some embodiments, the resistor 331 is connected in parallel with each battery cell 321. When equalization is performed, the battery cell 321 that needs to be equalized forms a path with the resistor 331. When current flows through the resistor 331, the resistor 331 generates heat, thereby dissipating excess electricity in the battery cell 321 as heat energy and reducing the voltage of the battery cell 321.

[0051] As shown in Figure 4, the battery pack 30 also includes a power management device 34, which is electrically connected to the cell assembly 32 to obtain the voltage of each cell unit 321. The power management device 34 is also configured to be connected to at least a voltage equalization circuit 33 to perform voltage equalization of the cell units 321 in equalization mode. When the power management device 34 detects a voltage difference between the cell units 321, it determines whether to enter the equalization mode according to a preset equalization strategy. Once the equalization mode is entered, the power management device 34 sends a control signal to the voltage equalization circuit 33, instructing it to start performing the equalization operation.

[0052] In one related technology, a battery pack 30 needs to periodically switch between odd and even cell units 321 for passive balancing during voltage equalization. Specifically, for the selected cell units 321 that need to be balanced, the odd-numbered cell units 321 are balanced first. Then, after balancing the odd-numbered cell units 321 for a period of time, the system switches to balancing the even-numbered cell units 321. After balancing the even-numbered cell units 321 for a period of time, the system switches back to balancing the odd-numbered cell units 321, and so on, periodically switching between odd and even cell units 321 for balancing.

[0053] To improve balancing efficiency and effect, in balancing mode, the power management device 34 is configured to: number the battery cells 321 requiring voltage balancing based on the acquired voltage output of each battery cell 321; calculate the maximum sum of voltages of the non-adjacent battery cells 321 among the numbered battery cells 321; and control the voltage balancing circuit 33 to perform voltage balancing on the battery cells 321 corresponding to the maximum voltage sum. In this way, the non-adjacent battery cell 321 with the largest voltage sum can be selected for power consumption at any given time, meaning that the battery cells 321 with larger voltage values ​​can be balanced first, resulting in better balancing effect and efficiency. The aforementioned maximum voltage sum refers to the maximum value of the sum of voltages of at least two of the remaining non-connected battery cells. In some embodiments, this includes sequentially numbered battery cells 1, 2, 3, 4, 5, and 6. Battery cell 4 needs to be balanced. For battery cell 4, the adjacent battery cells are battery cells 3 and 5. The non-adjacent battery cells are battery cells 1, 2, and 6. The possible combinations of the voltages of at least two cells are the sum of the voltages of cell 1 and cell 2, the sum of the voltages of cell 1 and cell 6, the sum of the voltages of cell 2 and cell 6, and the sum of the voltages of cell 1, cell 2, and cell 6.

[0054] Figure 5 is a comparison of the voltage equalization method of this application and the voltage equalization method of related technologies. As shown in Figure 5, L1 and L2 are the voltage data sampled by the related technologies, which takes about 29 minutes. L3 and L4 are the voltage data sampled by the voltage equalization method provided in this application, which takes about 23 minutes, and the equalization effect is improved by about 20%.

[0055] In some embodiments, `excl` indicates that no cell is currently selected, `incl` indicates the voltage value of the currently selected cell, `exindex` indicates the result of the unselected cell unit 321, `inindex` indicates that the bit position of the selected cell is 1, `excl_new` is the updated value after one selection, and `exindex_new` is the updated value after one selection. The output of this algorithm is a binary result. Taking 6 cells as an example, if it is 000000, it means that none of the 6 cells 321 need to be balanced; 010101 (counting from right to left) means that the 1st, 3rd, and 5th cells 321 need to be balanced, and so on.

[0056] The power management device 34 is configured as follows: First, set excl = 0, incl = the voltage value of the first cell, exindex = 0, and inindex = the position of the first cell (000001). If, after the first calculation, excl > incl, then in the second calculation, excl_new = excl, exindex_new = exinex, meaning that the previously calculated excl and exindex are assigned to this calculation; if incl > excl, then in the second calculation, excl_new = incl, exindex_new = ininex, meaning that the previously calculated incl and inindex are assigned to this calculation; and so on, until the last cell unit 321 is calculated. After calculating the last cell unit 321, if incl > excl, inindex is the cell that needs balancing; otherwise, exindex is the cell that needs balancing; then the voltage balancing circuit 33 is activated to cause the cell unit 321 that needs balancing to discharge through resistor 331 to consume power. This cycle repeats until balancing is no longer needed. The dynamic programming iterative algorithm described above reduces the passive equalization time and the timing of switching between odd and even cells. Furthermore, when passive equalization is interrupted, there is no need to restart recording the time, which improves the equalization effect after the interruption.

[0057] The following specific embodiment illustrates the method for determining the maximum voltage and the corresponding cell unit 321. This embodiment uses a 6-cell cell unit 321 as an example. The 6-cell cell unit 321 are numbered V1, V2, V3, V4, V5, and V6, where V1 = 4200mV, V2 = 4180mV, V3 = 4210mV, V4 = 4190mV, V5 = 4180mV, and V6 = 4210mV. The results calculated by the above dynamic programming iterative algorithm are shown in Table 1, where units are not shown.

[0058] Table 1: Data of non-adjacent cell 321 with maximum voltage calculated using dynamic programming iterative algorithm

[0059] As can be seen from Table 1, the maximum voltage and the corresponding cell unit 321 at this time are 1, 3, and 5 cell units 321. Therefore, this round balances the 1, 3, and 5 cell units 321.

[0060] In some embodiments, the power management device 34 is configured to: acquire the voltage of all battery cells 321, acquire the numbers of the battery cells 321 that need voltage equalization, create an array to mark which battery cells 321 are selected, and then combine the non-adjacent battery cells 321 among the battery cells 321 that need voltage equalization. All combinations of non-adjacent battery cells 321 are generated using a recursive or dynamic programming method. The recursive method can be implemented using backtracking, where after selecting a battery cell 321, its adjacent battery cells 321 are skipped, and the next one is selected. The dynamic programming method can be optimized using state compression or bitwise operations. Then, for each generated combination of non-adjacent battery cells 321, its voltage sum is calculated. The voltage sum and the corresponding combinations of battery cell 321 numbers are stored. All stored voltage sums are traversed, the combination of non-adjacent battery cells 321 with the largest voltage sum is found, and the numbers of each battery cell 321 in the combination of non-adjacent battery cells 321 with the largest voltage sum are output. It is understood that in other embodiments, the power management device 34 may also be configured to use other algorithms to obtain the maximum voltage and the corresponding battery cell 321. This is not a specific limitation, but just an example.

[0061] In some embodiments, as shown in Figures 2 and 4, the power management device 34 further includes an equalization judgment unit 341, which is configured to instruct the battery pack 30 to enter an equalization mode when the voltage difference between the maximum and minimum voltage values ​​in the voltages of each cell unit 321 is greater than a first voltage threshold.

[0062] The equalization determination unit 341 is responsible for determining whether to enter the equalization mode based on preset conditions. In some embodiments, the equalization determination unit 341 includes a control module. In some embodiments, the control module includes a control chip. The control chip includes one of a microcontroller, a digital signal processor, a field-programmable gate array, and an application-specific integrated circuit; in this embodiment, the control chip is a microcontroller.

[0063] The maximum voltage refers to the highest voltage value among all the cell units 321 in the battery pack 30. This value reflects the energy storage state of the cell unit 321 with the highest voltage in the battery pack 30. The minimum voltage is the lowest voltage value among all the cell units 321 in the battery pack 30. This value reflects the energy storage state of the cell unit 321 with the lowest voltage in the battery pack 30. The voltage difference is the difference between the maximum and minimum voltage values, reflecting the voltage inconsistency among the cell units 321 in the battery pack 30.

[0064] The first voltage threshold is a preset voltage difference value used to determine whether to enter the equalization mode. When the voltage difference between the cell units 321 exceeds this threshold, it indicates that the voltage inconsistency of the cell units 321 in the battery pack 30 has reached a level that requires equalization measures. In some embodiments, the first voltage threshold is substantially the same as 100mV.

[0065] When the voltage difference between the maximum and minimum voltage values ​​in each cell unit 321 exceeds a first voltage threshold, the battery pack 30 is instructed to enter the balancing mode, which enables timely balancing of the battery pack 30 when the voltage inconsistency reaches a level requiring balancing measures.

[0066] In some embodiments, as shown in Figures 2 and 4, the equalization judgment unit 341 is configured to instruct the battery pack 30 to exit the equalization mode when the voltage difference between the maximum and minimum voltage values ​​of each cell unit 321 is less than or equal to a first voltage threshold. In the equalization mode, the voltage equalization circuit 33 equalizes the cell units 321, consuming a certain amount of energy. When the voltage difference between the maximum and minimum voltage values ​​of the cell units 321 is less than or equal to the first voltage threshold, it indicates that the voltage inconsistency of the battery pack 30 is small, and continuing the equalization operation is no longer necessary. Therefore, exiting the equalization mode saves energy. Furthermore, avoiding unnecessary equalization operations reduces the workload of the battery pack 30, thereby improving its efficiency. At the same time, frequent equalization operations may cause some wear and tear on the cell units 321. When the voltage difference between the cell units 321 is sufficiently small, exiting the equalization mode can reduce this wear and tear, thereby extending the service life of the battery pack 30.

[0067] In some embodiments, the power management device 34 is configured to designate cell units 321 whose voltage difference from the minimum voltage value is greater than a first voltage threshold as cell units 321 requiring voltage equalization. This equalization operation helps reduce voltage differences between cell units 321, preventing some cell units 321 from over-discharging or over-charging, thereby extending the lifespan of the entire battery pack 30. When the voltage difference between the minimum voltage value and the voltage of a certain cell unit 321 is greater than the first voltage threshold, it indicates that the voltage of that cell unit 321 is too high, and therefore that cell unit 321 is identified as requiring voltage equalization.

[0068] In some embodiments, as shown in Figures 2 and 4, the power management device 34 further includes an analog front-end chip 342 for acquiring the voltage of each battery cell 321. The analog front-end chip 342 (AFE) is an integrated circuit for signal processing, whose core function is to convert analog signals into digital signals for subsequent analysis and processing by a digital system. In the battery pack 30, the analog front-end chip 342 can monitor the voltage of each battery cell 321 and convert it into a digital signal for output to the equalization judgment unit 341.

[0069] In some embodiments, the analog front-end chip 342 is connected to the voltage equalization circuit 33 to control the operation of the voltage equalization circuit 33. Specifically, when the voltage equalization circuit 33 includes a resistor 331, the analog front-end chip 342 first samples the voltage of each battery cell 321. Then, the equalization judgment unit 341 obtains the voltage of each battery cell 321 and calculates which battery cells 321 need to be equalized. The equalization judgment unit 341 then communicates with the analog front-end chip 342 to tell it which battery cells 321 need to be equalized. The analog front-end chip 342 then controls the battery cells 321 to be equalized to discharge to the corresponding resistor 331, thereby achieving equalization.

[0070] In some embodiments, as shown in Figures 2 and 6, the power tool 20 further includes a button 35, which is electrically connected to the analog front-end chip 342 and is used to wake up the analog front-end chip 342 when pressed. In some embodiments, the analog front-end chip 342 includes a power supply port, and the battery pack 30 is powered by the power supply port of the analog front-end chip 342. Specifically, the power supply port of the analog front-end chip 342 is electrically connected to the equalization judgment unit 341 and is used to provide power to the equalization judgment unit 341. Specifically, the power-on process of the battery pack 30 is as follows: the button 35 is pressed or an external communication connection is established to wake up the analog front-end chip 342, and then the analog front-end chip 342 outputs power to power up the equalization judgment unit 341, which determines whether to start running the battery pack 30 based on whether the analog front-end chip 342 is configured. The power-off process of the battery pack 30 is as follows: the equalization judgment unit 341 sends a deep sleep command to the analog front-end chip 342, and at the same time, the equalization judgment unit 341 sends a power-off command to make the analog front-end chip 342 turn off the power supply output of the power supply port. At this time, the equalization judgment unit 341 is de-energized, and the battery pack 30 is de-energized. In some embodiments, the power management device further includes a controller, which is at least used to manage the charging and discharging state of the battery pack. The analog front-end chip is configured to be woken up by a button or external communication, and the controller is powered on by the analog front-end chip. The controller sends a deep sleep command to the analog front-end chip to enter deep sleep mode. Upon receiving the command, the analog front-end chip shuts down its power supply output, thereby powering off the controller.

[0071] In some embodiments, this application also provides a voltage equalization method for a battery pack, used to perform voltage equalization on the battery pack described in any embodiment of this application, as shown in FIG7, the voltage equalization method includes:

[0072] S110: Obtain the voltage of each cell unit in the battery pack.

[0073] S120. The cell number that needs to be balanced based on the obtained voltage output.

[0074] S130. Calculate the maximum voltage of the non-adjacent cell units in the cell unit corresponding to the number.

[0075] S140, Perform voltage balancing operation on the maximum voltage and the corresponding cell unit.

[0076] In some embodiments, as shown in FIG8, the flowchart of the voltage equalization method for the battery pack in the above embodiments specifically includes the following steps:

[0077] S210: Obtain the voltage of each cell unit in the battery pack.

[0078] S220. When the voltage difference between the maximum and minimum voltage values ​​of each cell unit is greater than the first voltage threshold, the battery pack is instructed to enter the equalization mode.

[0079] S230. In equalization mode, the cell numbers that need to be equalized based on the obtained voltage output.

[0080] S240. Calculate the maximum voltage of the non-adjacent cell units in the cell unit corresponding to the number.

[0081] S250, Perform voltage balancing operation on the maximum voltage and the corresponding cell unit.

[0082] In some embodiments, as shown in FIG9, the flowchart of the voltage equalization method for the battery pack in the above embodiments specifically includes the following steps:

[0083] S310: Obtain the voltage of each cell unit in the battery pack.

[0084] S320. When the voltage difference between the maximum and minimum voltage values ​​of each cell unit is greater than the first voltage threshold, the battery pack is instructed to enter the equalization mode.

[0085] S330. In equalization mode, the cell numbers that need to be equalized based on the obtained voltage output.

[0086] S340. Calculate the sum of the maximum voltages of the non-adjacent cell units in the cell unit corresponding to the number.

[0087] S350, Perform voltage balancing operation on the maximum voltage and the corresponding cell unit.

[0088] S360: When the voltage difference between the maximum and minimum voltage values ​​in each cell is less than or equal to the first voltage threshold, the battery pack is instructed to exit the equalization mode.

[0089] In some embodiments, the step of determining the cell numbers that need to be balanced based on the obtained voltage output includes: setting cell numbers whose voltage difference with the minimum voltage value is greater than a first voltage threshold as cell numbers that need to be balanced, and outputting the cell numbers that need to be balanced.

[0090] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that the above embodiments do not limit this application in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of this application.

Claims

1. A battery pack (30), comprising: The battery cell assembly (32) includes multiple battery cell units (321) that provide discharge current to power the power tool (20); A voltage equalization circuit (33) is electrically connected to the battery cell assembly and is used to equalize the voltage of each battery cell unit; A power management device (34) is electrically connected to the battery cell assembly to obtain the voltage of each of the battery cell units; the power management device is connected to the voltage equalization circuit and performs voltage equalization on the multiple battery cell units based on the voltage equalization circuit; The power management device is configured to acquire the voltage of each of the battery cells; determine the number of the battery cell that needs voltage equalization based on the acquired voltage, and estimate the sum of the maximum voltages of the non-adjacent battery cells corresponding to the number; and control the voltage equalization circuit to perform voltage equalization on the battery cells corresponding to the sum of the maximum voltages.

2. The battery pack of claim 1, wherein, The power management device further includes a voltage equalization judgment unit (341), which is configured to control the battery pack to operate in the voltage equalization mode when the voltage difference between the maximum and minimum voltage values ​​of each of the battery cells is greater than a first voltage threshold.

3. The battery pack of claim 2, wherein, The equalization judgment unit is configured to control the battery pack to exit the equalization mode when the voltage difference between the maximum and minimum voltage values ​​of each of the battery cells is less than or equal to the first voltage threshold.

4. The battery pack of claim 2, wherein, The power management device is configured to acquire the voltage of each of the battery cells, and when the voltage difference between the voltage and the minimum voltage value is greater than the first voltage threshold, the power management device marks the corresponding battery cell as a battery cell that needs to be voltage balanced.

5. The battery pack of claim 2, wherein, The first voltage threshold is basically set to 100mV.

6. The battery pack of claim 1, wherein, The power management device also includes an analog front-end chip (342) for acquiring the voltage of each of the battery cells.

7. The battery pack of claim 6, wherein, The analog front-end chip is connected to the voltage equalization circuit and is used to control the operation of the voltage equalization circuit.

8. The battery pack of claim 6, wherein, The power management device further includes a controller, which is used at least to manage the charging and discharging state of the battery pack.

9. The battery pack of claim 8, wherein, The analog front-end chip is configured to be woken up by a button or external communication, and the controller is woken up and powered on by the analog front-end chip.

10. The battery pack of claim 9, wherein, The controller sends a deep sleep command to the analog front-end chip to enter deep sleep mode. After receiving the command, the analog front-end chip shuts down its power supply output to power off the controller.

11. The battery pack of claim 1, wherein, The voltage equalization circuit includes resistors (311) connected to each of the battery cells.

12. The battery pack according to claim 1, wherein the rated voltage of the battery pack is greater than or equal to 24V and less than or equal to 80V.

13. The battery pack of claim 1, further comprising a terminal assembly including electrode terminals electrically connectable to a power tool.

14. The battery pack of claim 10, further comprising a housing having a connection guide portion formed or connected thereto, which guides the electrode terminals to be electrically connected to the power tool. 15.A method for voltage balancing of a battery pack, wherein, obtaining voltages of each battery cell unit of the battery pack; determining, based on the obtained voltages, a number of the battery cell units that need to perform voltage balancing; calculating a maximum voltage sum of non-adjacent battery cell units of the battery cell unit corresponding to the number; performing a voltage balancing operation on the battery cell unit corresponding to the maximum voltage sum.

16. The method of balancing the voltage of a battery pack according to claim 15, wherein, obtaining a maximum voltage and a minimum voltage of each of the battery cell units, and when a voltage difference between the maximum voltage and the minimum voltage is greater than a first voltage threshold, controlling the battery pack to work in the voltage balancing mode.

17. The voltage equalization method of claim 16, wherein, when the voltage difference between the maximum voltage and the minimum voltage is less than or equal to the first voltage threshold, controlling the battery pack to exit the voltage balancing mode.

18. The voltage equalization method of claim 17, wherein, obtaining a voltage of each of the battery cell units, and when a voltage difference between the voltage and the minimum voltage is greater than a first voltage threshold, marking the corresponding battery cell unit as a battery cell unit that needs to perform voltage balancing.

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