A battery pack packaging method, system and storage medium

Abstract

The present application provides a method, system and storage medium for parallel packing of battery packs. The method includes: step S1, obtaining the open circuit voltage of each battery pack; step S2, sorting each battery pack according to the size of the open circuit voltage; step S3, controlling the battery pack in the front order to open, forming an online battery pack, and controlling the remaining battery packs to close; step S4, sequentially obtaining the voltage difference between the battery pack to be incorporated and the online battery pack; step S5, judging whether the voltage difference is within a preset range, if so, executing step S6; step S6, controlling the battery pack to be incorporated and the online battery pack to be paralleled to obtain a paralleled battery; step S7, using the paralleled battery as an online battery pack, repeating steps S4 and S5 until the voltage difference exceeds the preset range, which reduces the safety hazards caused by the large voltage difference, and can reduce the power consumption loss caused by the battery packs in the online battery pack complementing each other.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a battery pack packaging method, system and storage medium. Background Art

[0002] In the field of energy storage, the construction of battery packs is crucial. By connecting two or more cells together, a battery pack can be formed, which significantly increases the available capacity of the entire battery pack. This connection method not only improves the energy density of the energy storage system, but also enables the number of cells to be flexibly adjusted during manufacturing according to different application scenarios and load requirements. For example, in electric vehicles, the capacity of the battery pack is directly related to the vehicle's range; in energy storage systems, the capacity of the battery pack determines how much electrical energy can be stored and how much electrical energy can be released during peak grid loads; and in portable electronic devices, the capacity of the battery pack affects the use time of the device. With the development of technology and the growth of market demand, the widespread application of electric vehicles, energy storage systems and portable electronic devices has put forward higher requirements on the performance and reliability of battery packs. The performance of the battery pack not only affects the operating efficiency of the entire system, but is also directly related to the service life of the equipment. Therefore, the design and manufacture of battery packs have become the focus of research and development in related fields.

[0003] However, in the process of implementing the embodiments of the present application, the inventors of the present application found that in some application scenarios, in order to meet the needs of higher energy density, higher safety and longer battery life, different battery packs are often required to be used in parallel to form a battery with a larger capacity. Summary of the invention

[0004] In view of the above problems, the present application provides a battery pack parallel packaging method, system and storage medium, which overcome the above problems or at least partially solve the above problem of needing to parallel pack and expand the capacity of battery packs.

[0005] According to one aspect of the present application, a method for parallel packing of battery packs is provided, and the method is applied to multiple battery packs that need to be paralleled, and the method includes: step S1, obtaining the open circuit voltage of each of the battery packs; step S2, sorting each of the battery packs according to the size of the open circuit voltage; step S3, controlling the battery pack in the front order to be in an open state to form an online battery pack, and controlling the remaining battery packs to be in a closed state; step S4, sequentially obtaining the voltage difference between the battery pack to be incorporated and the online battery pack, and the battery pack to be incorporated is the battery pack in the rear order; step S5, judging whether the voltage difference is within a preset range, and if so, executing step S6; step S6, controlling the battery pack to be incorporated to be paralleled with the online battery pack to obtain a paralleled battery; step S7, taking the paralleled battery as the online battery pack, and repeating steps S4 and S5 until the voltage difference exceeds the preset range.

[0006] In an optional manner, the preset range in step S5 is obtained according to the product of the resistance of the online battery pack and the current charge / discharge current, and the product of the maximum allowable charge / discharge current and the resistance of the battery pack to be incorporated.

[0007] In an optional manner, the step S2 includes: when the battery pack is in a static state or a discharging state, sorting each of the battery packs in descending order according to the size of the open circuit voltage, and the open circuit voltage of the battery pack in the front order is the largest.

[0008] In an optional manner, when the battery pack is in a stationary state, the formula of step S5 is:

[0009] ∆U si ≤Imaxs×R si

[0010] Among them, the ∆U si is the voltage difference between the first i-1 online battery packs and the i-th battery pack to be incorporated in the static state, and the Imaxs×R si is the preset range in the static state, wherein Imaxs is the maximum allowable charging current of the ith battery pack to be incorporated in the static state, and R si is the resistance of the ith battery pack to be incorporated in the static state;

[0011] The Imaxs satisfy:

[0012] Imaxs=Min{I chg-socsi ×SOH i , I chg-Tsi ×SOH i}

[0013] Among them, the SOH i is the health status value of the i-th battery pack to be incorporated;

[0014] Among them, the I chg-socsi When in the static state, the charging SOC current of the i-th battery pack to be incorporated is limited by the charging SOC; the I chg-Tsi When in the stationary state, the charging temperature current of the i-th battery pack to be incorporated is limited by the charging temperature.

[0015] In an optional manner, when the battery pack is in a discharging state, the formula of step S5 is:

[0016]

[0017] Among them, the ∆U di is the voltage difference between the ith battery pack to be incorporated and the first i-1 online battery packs in the discharge state, the λ×I d(i-1) ×R d(i-1) and the Imaxd×R di The preset range in the discharge state is limited, wherein λ is a proportionality coefficient, Imaxd is the maximum allowable discharge current of the ith battery pack to be incorporated in the discharge state, and R d(i-1) is the resistance of the first i-1 online battery packs in the discharge state, and the R di is the resistance of the ith battery pack to be incorporated in the discharge state; d(i-1) The sum of the current discharge currents of the battery packs in the first i-1 online battery packs when in the discharge state.

[0018] In an optional manner, the Imaxd satisfies:

[0019] Imaxd=Min{I dsg-SOCdi ×SOH i , I dsg-Tdi ×SOH i}

[0020] Among them, the SOH i is the health status value of the i-th battery pack to be incorporated;

[0021] Among them, the I dsg-SOCdi When the battery pack to be incorporated is in the discharge state, the discharge SOC current of the i-th battery pack to be incorporated is limited by the discharge SOC; the I dsg-Tdi When in the discharging state, the discharge temperature current of the i-th battery pack to be incorporated is limited by the discharge temperature.

[0022] In an optional manner, the step S2 includes: when the battery pack is in a charging state, sorting the battery packs in ascending order according to the size of the open circuit voltage, and the open circuit voltage of the battery pack in the front order is the smallest.

[0023] In an optional manner, when the battery pack is in a charging state, the formula of step S5 is:

[0024]

[0025] Among them, the ∆U ci is the voltage difference between the first i-1 online battery packs and the i-th battery pack to be incorporated in the charging state, the λ×I c(i-1) ×R c(i-1) and the Imaxc×R ci The preset range when the charging state is limited, wherein the λ is a proportionality coefficient, the Imaxc is the maximum allowable charging current of the i-th battery pack to be incorporated in the charging state, and the R c(i-1) is the resistance of the first i-1 online battery packs in the charging state, the R ci is the resistance of the ith battery pack to be incorporated in the charging state; c(i-1) The sum of the current charging currents of the battery packs in the first i-1 online battery packs when the battery pack is in the charging state.

[0026] In an optional manner, the Imaxc satisfies:

[0027] Imaxc=Min{I chg-SOCci ×SOH i , I chg-Tci ×SOH i}

[0028] Among them, the SOH i is the health status value of the i-th battery pack to be incorporated;

[0029] Among them, the I chg-SOCci When the charging state is the charging state, the charging SOC current of the i-th battery pack to be incorporated is limited by the charging SOC; the I chg-Tci When in the charging state, the charging temperature current of the i-th battery pack to be incorporated is limited by the charging temperature.

[0030] In an optional manner, the open circuit voltage of each battery pack is obtained with sampling accuracy in step S1, and the proportionality coefficient is greater than twice the sampling accuracy.

[0031] According to one aspect of an embodiment of the present application, a battery pack paralleling system is provided, which is applied to multiple battery packs that need to be paralleled, and the system includes: a first acquisition module, used to acquire the open-circuit voltage of each of the battery packs; a sorting module, used to sort each of the battery packs according to the size of the open-circuit voltage; the first paralleling module, used to control the battery pack in the front sorting to be in an open state to form an online battery pack, and control the remaining battery packs to be in a closed state; a second acquisition module, used to sequentially acquire the voltage difference between the battery pack to be incorporated and the online battery pack, the battery pack to be incorporated being the battery pack in the rear sorting; a judgment module, used to judge whether the voltage difference is within a preset range, and if so, enter the second paralleling module; the second paralleling module, used to control the battery pack to be incorporated to be paralleled with the online battery pack to obtain a paralleled battery; and a third paralleling module, used to use the paralleled battery as the online battery pack, and repeatedly execute the second acquisition module and the judgment module until the voltage difference exceeds the preset range.

[0032] According to one aspect of an embodiment of the present application, a battery pack parallel packaging system is provided, the system comprising: at least one processor, and a memory, the memory being communicatively connected to the at least one processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor so that the at least one processor can execute the method as described above.

[0033] According to one aspect of an embodiment of the present application, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the steps of the above method.

[0034] The beneficial effects of the present application include: through the battery pack paralleling method, the battery packs are sorted according to the size of the open circuit voltage, and then the battery packs are paralleled according to the principle of similar voltage, which effectively reduces the safety hazards caused by large voltage differences, and can greatly reduce the power consumption loss caused by mutual power replenishment between the battery packs in the online battery pack. This not only meets the user's needs for parallel packing to expand the available capacity of the battery pack, but also meets the user's expectation for the longest possible service life of the battery pack.

[0035] In addition, when the battery packs are connected in parallel, a step is introduced to determine whether the pressure difference is within a preset range. The connection operation is performed only when the pressure difference is within the preset range, thereby effectively preventing the generation of circulating current and improving the stability, safety and efficiency of the battery pack.

[0036] It is also important that, since the principle of similar voltages is adopted for paralleling, paralleling is not performed when the voltage difference is large. After the paralleling system is connected to charging or discharging, as the charging or discharging progresses, the voltages of the online battery pack and the battery pack to be paralleled are close, and then the packs are paralleled. There is no need to use, for example, a Buck circuit to forcibly level the voltage difference between the battery packs (between the online battery pack and the battery pack to be paralleled), which saves hardware costs and makes the hardware circuit more flexible and simple in solution design.

[0037] In a further beneficial effect, by considering the real-time current under different working conditions (stationary state, charging state, discharging state), the resistance of the online battery pack, the maximum allowable charge / discharge current of the battery pack to be incorporated, and the resistance of the battery pack to be incorporated in real time, the current state of the battery pack can be judged more accurately, and the real-time and accurate allowable voltage difference range for the package (ie, the preset range) can be obtained, thereby making the package process safer. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0039] Figure 1 is a schematic diagram of a system provided in an embodiment of the present application;

[0040] Figure 2 is a schematic diagram of another system provided in an embodiment of the present application;

[0041] Figure 3 Schematic diagram of the hardware structure of the master control BMS module provided in the embodiment of the present application;

[0042] Figure 4 It is a schematic flow chart of a method for packing battery packs provided in an embodiment of the present application;

[0043] Figure 5 It is an example schematic diagram of sorting in descending order a plurality of battery packs that need to be packed in a static state or a discharging state provided in an embodiment of the present application;

[0044] Figure 6 is an example schematic diagram of each battery pack that meets the packing conditions in a static state provided in an embodiment of the present application;

[0045] Figure 7 This is an example schematic diagram of the state after packaging in a static state provided by an embodiment of the present application;

[0046] Figure 8is an example schematic diagram of each battery pack that meets the packing conditions in the discharge state provided in the embodiment of the present application;

[0047] Fig. 9 is an example schematic diagram of each battery pack that does not meet the packing conditions in the discharge state provided in the embodiment of the present application;

[0048] Fig.10 This is an example schematic diagram of an embodiment of the present application in which the conditions for packaging are met in a discharge state;

[0049] Fig.11 is an example schematic diagram of each battery pack that meets the packing conditions again in the discharge state provided in the embodiment of the present application;

[0050] Fig.12 This is an example schematic diagram of an embodiment of the present application in which the packing condition is met again in the discharge state;

[0051] Fig.13 is an example schematic diagram of sorting in ascending order a plurality of battery packs that need to be packed together in a charging state provided by an embodiment of the present application;

[0052] Fig.14 is an example schematic diagram of each battery pack that meets the packing conditions in the charging state provided in the embodiment of the present application;

[0053] Fig.15 is an example schematic diagram of each battery pack that does not meet the packing conditions in the charging state provided in the embodiment of the present application;

[0054] Fig.16 This is an example schematic diagram of an embodiment of the present application in which the conditions for combining packages are met in a charging state;

[0055] Fig.17 is an example schematic diagram of each battery pack that meets the packing conditions again in the charging state provided in the embodiment of the present application;

[0056] Fig.18 This is an example schematic diagram of an embodiment of the present application in which the packing condition is met again in the charging state;

[0057] Fig.19 It is a schematic diagram of a battery pack packaging system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field belong to the scope of protection of this application.

[0059] In addition, the technical features involved in the embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0060] See also Figure 1 , Figure 1 It is a schematic diagram of the battery pack parallel packaging system provided in an embodiment of the present application, and the system is applicable to the battery pack parallel packaging method. The system includes multiple battery packs 10 and a master BMS (Battery Management System) module 20. Each battery pack 10 includes a battery group and a corresponding slave BMS module. Each slave BMS module communicates internally with the master BMS module. In addition, the system can also be connected to an external device 200 (such as an inverter, photovoltaic, charger, etc.) to build an efficient power conversion and storage system. The parallel packaging system 100 can be specifically configured in a variety of ways, not limited to Figure 1 For example, see Figure 2 , Figure 2 This is another schematic diagram of the battery pack parallel pack system provided in an embodiment of the present application. The system's master BMS module 20 does not need to be set up separately, and can be performed by one of the multiple battery packs 10. The BMS modules of the remaining battery packs 10 operate as slave BMS modules. This not only simplifies the system structure, but also effectively reduces costs, while ensuring the normal operation and efficient management of the system.

[0061] The battery pack may be a lithium-ion battery pack, which mainly includes consumer battery packs, power battery packs and energy storage battery packs. Among them, the consumer battery pack usually requires small size, light weight, high energy density and long cycle life, and is widely used in personal electronic devices such as mobile phones, laptops, tablet computers, digital cameras and portable music players. Among them, the power battery pack is mainly used in new energy vehicles, electric bicycles, electric trains and other means of transportation to provide the instantaneous high power output required by the vehicle to support operations such as acceleration and climbing. Among them, the energy storage battery pack is mostly used as a battery pack energy storage system for renewable energy such as solar energy, wind power, hydropower, as well as grid peak and frequency regulation, backup power supply, microgrid and other occasions, mainly used for long-term storage and stable release of energy.

[0062] The master BMS module 20 is responsible for the high-level management and control of the entire battery system, including but not limited to the balancing management between battery packs, the overall monitoring of the system status, and the communication with external devices (such as inverters, chargers, etc.); collects data from each slave BMS module and conducts a comprehensive analysis to evaluate the health and performance of the entire system; makes key decisions such as charging / discharging strategies and fault response measures based on the collected data and system requirements; implements system-level safety strategies to prevent overcharging, over-discharging, over-temperature, etc. that may cause damage to the battery; provides operators with an intuitive interface to display system status, warning information, etc. for easy monitoring and management.

[0063] The slave BMS module focuses on monitoring the status of the battery group inside a single battery pack 10, such as key parameters such as voltage, current, and temperature. Once any abnormal situation is detected, such as overvoltage, undervoltage, and overtemperature of a single battery, protective measures are immediately taken, such as disconnecting the circuit, to avoid damage to the battery pack. The monitored data is transmitted to the master BMS module in a timely and accurate manner for higher-level analysis and decision-making. The slave BMS module receives and executes instructions from the master BMS module, such as adjusting the charge / discharge rate, activating the cooling system, etc. The slave BMS module achieves balance between battery cells in a single battery pack to ensure that each cell can achieve the best working state, thereby extending the service life of the battery pack.

[0064] Through the coordinated work of the master BMS module and the slave BMS module, refined management and control of the entire battery system can be achieved, ensuring that the system can operate stably and efficiently under various operating conditions.

[0065] Embodiment 1

[0066] Before introducing the battery pack assembly method in detail, the hardware structure of the main control BMS module 20 provided in the embodiment of the present application is described.

[0067] See also Figure 3 , Figure 3 : is a hardware structure diagram of the master control BMS module 20 provided in the embodiment of the present application, which can execute the battery pack packaging method. The master control BMS module 20 includes

[0068] At least one processor 21 and memory 22 (communicatively connected Figure 3 A bus connection and a processor are used as an example). A person skilled in the art can understand that Figure 3 The structure shown is only for illustration and does not limit the structure of the master control BMS module 20. For example, the master control BMS module 20 may also include Figure 3 More or fewer components as shown, or with Figure 3 Different configurations shown.

[0069] The processor 21 is used to provide computing and control capabilities, and to control the main control BMS module 20 to execute any method provided in the following application embodiments, thereby managing the battery pack 10 accordingly.

[0070] It can be understood that the processor 21 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0071] The memory 22, as a non-transient computer-readable storage medium, can be used to store non-transient software programs, non-transient computer executable programs and modules, such as program instructions / modules corresponding to the various calculation methods in the embodiments of the present application. The processor 21 can implement the various calculation methods in any of the following method embodiments by running the non-transient software programs, instructions and modules stored in the memory 22. The memory 22 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory 22 may also include a memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network and a combination thereof.

[0072] Embodiment 2

[0073] The embodiment of the present application also provides a non-volatile computer-readable storage medium, wherein the non-volatile computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used by a battery to execute each calculation method in any of the following method embodiments.

[0074] An embodiment of the present application provides a computer program product, including a computing program stored on a non-volatile computer-readable storage medium, wherein the computer program includes program instructions, and when the program instructions are executed by a computer, the computer executes each computing method in any of the following method embodiments.

[0075] Through the description of the above implementation methods, ordinary technicians in this field can clearly understand that each implementation method can be implemented by means of software plus a general hardware platform, and of course it can also be implemented by hardware. Ordinary technicians in this field can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, the storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0076] Embodiment 3

[0077] The following is a discussion of the battery pack assembly method provided in the embodiment of the present application. Figure 4 , Figure 4 : is a flow chart of a method for packing a battery pack provided in an embodiment of the present application, the method comprising the following steps:

[0078] Step S1, obtaining the open circuit voltage of each battery pack.

[0079] Among them, the open circuit voltage refers to the voltage difference between the positive and negative electrodes of the battery pack when it is in the open circuit state (that is, when no load is connected).

[0080] The method for obtaining the open circuit voltage of the battery pack is to measure the voltage difference between the positive and negative electrodes of the battery pack, which can be measured using a voltage measuring device (such as a voltmeter, a voltage sensor, etc.) or obtained through a measuring circuit. The open circuit voltage (the voltage difference between the positive and negative electrodes of the battery pack) can be transmitted to the slave BMS module and the master BMS module by wired or wireless means for further processing.

[0081] For a battery pack in a static state, the voltage difference between the positive and negative electrodes of the battery pack can be directly measured. For a battery pack in a charging / discharging state, its open circuit voltage can be inferred from the real-time sampled terminal voltage and the charge / discharge current.

[0082] Step S2, sorting the battery packs according to the open circuit voltage.

[0083] According to the open circuit voltage of each battery pack, each battery pack can be sorted, and the battery pack in the front order and the battery pack in the order can be obtained. The battery pack in the front order will be used for the packing operation with the battery pack in the back order (the battery pack to be incorporated).

[0084] In some embodiments, when the battery pack is in a static state (the battery pack is not performing a charge or discharge operation, i.e., no current is passing through the battery pack) or a discharging state, each of the battery packs is sorted in descending order according to the size of the open circuit voltage, and the open circuit voltage of the battery pack in the front order is the largest, and the open circuit voltages of the remaining battery packs in the back order decrease in sequence.

[0085] For example, when the battery pack is in a static state or a discharging state, there are m battery packs that need to be packed in parallel, where m is a positive integer not less than 2. For example, when m is 5, the battery packs are sorted in descending order according to the size of the open circuit voltage to form the first battery pack, the second battery pack, the third battery pack, the fourth battery pack and the fifth battery pack; assuming that the open circuit voltage of the first battery pack is U1, the open circuit voltage of the second battery pack is U2, the open circuit voltage of the third battery pack is U3, the open circuit voltage of the fourth battery pack is U4, and the open circuit voltage of the fifth battery pack is U5, then U1≥U2≥U3≥U4≥U5.

[0086] In some embodiments, when the battery packs are in a charging state, the battery packs are sorted in ascending order according to the size of their open circuit voltages, the open circuit voltage of the battery pack in the front order is the smallest, and the open circuit voltages of the remaining battery packs in the back order increase in sequence.

[0087] For example, when the battery pack is in a charging state, there are m battery packs that need to be packed in parallel, where m is a positive integer not less than 2. For example, when m is 5, the battery packs are sorted in ascending order according to the size of the open circuit voltage to form the ①th battery pack, the ②th battery pack, the ③th battery pack, the ④th battery pack and the ⑤th battery pack; assuming that the open circuit voltage of the ①th battery pack is U 11 , the open circuit voltage of the second battery pack is U 12 , the open circuit voltage of the third battery pack is U 13 , the open circuit voltage of the fourth battery pack is U 14 , the open circuit voltage of the fifth battery pack is U 15 , then U 11 ≤U 12 ≤U 13 ≤U 14 ≤U 15 .

[0088] Step S3, controlling the battery pack in the front order to be in an on state to form an online battery pack, and controlling the remaining battery packs to be in an off state.

[0089] The on state refers to a state in which the battery pack can be charged and discharged externally. In some embodiments, the method of controlling the battery pack in the front order to be in the on state may be to keep the MOS tube (Metal-Oxide-Semiconductor Field-Effect Transistor) in the on state, or to keep the relay on, or to keep other switch devices on.

[0090] The off state refers to the state where the remaining battery packs cannot be charged or discharged. In some embodiments, the remaining battery packs can be controlled to be in the off state by keeping the MOS tubes off, or keeping the relays off, or keeping other switch devices off.

[0091] It is worth noting that the online battery pack is the battery pack that is in the front order and is in the turned-on state.

[0092] Step S4, sequentially obtaining the voltage difference between the battery pack to be incorporated and the online battery pack, wherein the battery pack to be incorporated is the battery pack that is arranged later.

[0093] The battery pack to be incorporated is a battery pack that needs to be packaged to form a packaged battery.

[0094] The battery pack to be incorporated is a battery pack that is ranked later, that is, a battery pack that is ranked after the last battery pack to be incorporated in the online battery pack. The battery pack to be incorporated is also one of the multiple battery packs that have not yet been incorporated, and is the battery pack that is ranked first among the multiple battery packs that have not yet been incorporated.

[0095] For example, in the above example, when the battery pack is in a static state or a discharging state, there are 5 battery packs that need to be combined. The battery packs are sorted in descending order according to the size of the open circuit voltage to form the first battery pack, the second battery pack, the third battery pack, the fourth battery pack and the fifth battery pack. After the first battery pack (the battery pack in the front order) is combined, the battery pack to be combined is the second battery pack; after the second battery pack is combined, the battery pack to be combined is the third battery pack...

[0096] For example, in the above example, when the battery pack is in a charging state, there are 5 battery packs that need to be combined, and each of the battery packs is sorted in ascending order according to the size of the open circuit voltage to form the ①th battery pack, the ②th battery pack, the ③th battery pack, the ④th battery pack and the ⑤th battery pack. After the ①th battery pack (the battery pack in the front order) is combined, the battery pack to be combined is the ②th battery pack; after the ②th battery pack is combined, the battery pack to be combined is the ③th battery pack.

[0097] Step S5, determining whether the pressure difference is within a preset range, if so, executing step S6.

[0098] The preset range is obtained based on the product of the resistance of the online battery pack and the current charge / discharge current, and the product of the maximum allowable charge / discharge current and the resistance of the battery pack to be incorporated. The formula can be expressed as follows:

[0099] λ×I (i-1) ×R (i-1) ≤∆U i ≤Imax×R i

[0100] Among them, λ is the proportionality coefficient, I (i-1) is the sum of the current charge / discharge currents of each battery pack in the first i-1 online battery packs, R (i-1) is the resistance of the first i-1 online battery packs, Imax is the maximum allowable charge / discharge current of the i-th battery pack to be incorporated, R i is the resistance to be incorporated into the i-th battery pack.

[0101] (1) In some embodiments, when the battery pack is in a stationary state, the formula of step S5 is:

[0102] ∆U si ≤Imaxs×R si

[0103] It should be noted that ∆U si The voltage difference is obtained by subtracting the open circuit voltage of the i-th battery pack to be integrated from the open circuit voltage of the first i-1 online battery pack.

[0104] In the static state, the sum of the current charge / discharge currents of each battery pack in the first i-1 online battery packs is 0, so λ×I (i-1) ×R (i-1) =0, the left half of the formula is omitted.

[0105] Among them, the ∆U si is the voltage difference between the ith battery pack to be incorporated and the first i-1 online battery packs in the static state, and Imaxs×R si is the preset range in the static state, wherein Imaxs is the maximum allowable charging current of the ith battery pack to be incorporated in the static state, and R si is the resistance of the ith battery pack to be incorporated in the static state;

[0106] In the static state, the reason why the preset range is taken as above is that: the number of battery packs to be connected each time is 1, and the number of online battery packs is n. Since n≥1, at the moment of connection, the average circulating current of the online battery pack is A / n, and the circulating current of the battery pack to be connected is A / 1. Therefore, the current passing through the battery pack to be connected is the largest, and the voltage difference threshold is mainly based on the battery pack to be connected, and the maximum does not exceed the maximum allowable charging current Imaxs of the battery pack to be connected. Different battery SOC, different temperatures, and different health status values ​​(SOH) all have an impact on the maximum allowable charging current Imaxs.

[0107] In a static state, the online battery pack will charge the battery pack to be incorporated, so it can be obtained by taking the smaller value of the product of the charging SOC current and SOH of the battery pack to be incorporated, which is limited by the charging SOC, and the product of the charging temperature current and SOH limited by the charging temperature. That is, the Imaxs satisfies:

[0108] Imaxs=Min{I chg-socsi ×SOH i , I chg-Tsi ×SOH i}

[0109] The SOH (State of Health) is the health status value of the ith battery pack to be incorporated. The SOH of a battery pack is an indicator used to measure the difference between the current performance of a battery and the performance of a new battery. SOH is usually determined by comparing the actual capacity of the battery pack with the initial capacity, reflecting the degree of battery aging and the estimated remaining usage time. The actual capacity can be obtained by the total charge or discharge amount in the last charge and discharge cycle or the average of the two. The SOH value is usually expressed as a percentage, 100% means that the battery is in a brand new state, and a lower percentage means that the battery performance has degraded. The I chg-socsi When in the static state, the charging SOC current of the i-th battery pack to be incorporated is limited by the charging SOC; the I chg-Tsi When in the stationary state, the charging temperature current of the i-th battery pack to be incorporated is limited by the charging temperature.

[0110] It is worth noting that for a specific battery pack, charging / discharging the battery pack needs to follow a certain charging / discharging rate, that is, a certain charging / discharging current, which is usually limited by the charging / discharging SOC of the battery pack and the charging / discharging temperature of the battery pack. When the battery pack leaves the factory, the charging / discharging current limited by the charging / discharging SOC of the battery pack and the charging / discharging temperature of the battery pack is usually included in the charging / discharging control strategy formed by the battery pack manufacturer according to the performance of the battery pack and written in the technical documents such as the battery pack specification. In some embodiments, the charging / discharging control strategy is written into the main control BMS module, so as to facilitate the acquisition of the above-mentioned discharge SOC current, discharge temperature current, charging SOC current and charging temperature current.

[0111] (2) In some embodiments, when the battery pack is in a discharging state, the formula of step S5 is:

[0112]

[0113] It should be noted that ∆U di The voltage difference is obtained by subtracting the open circuit voltage of the first i-1 online battery packs from the open circuit voltage of the i-th battery pack to be integrated, that is, it is required that in the discharge state, the open circuit voltage of the online battery pack should drop below the open circuit voltage of the battery pack to be integrated.

[0114] Among them, the ∆U di is the voltage difference between the ith battery pack to be incorporated and the first i-1 online battery packs in the discharge state, the λ×I d(i-1) ×R d(i-1) and the Imaxd×R di The preset range in the discharge state is limited, wherein λ is a proportionality coefficient, Imaxd is the maximum allowable discharge current of the ith battery pack to be incorporated in the discharge state, and R d(i-1) is the resistance of the first i-1 online battery packs in the discharge state, and the R di is the resistance of the ith battery pack to be incorporated in the discharge state; d(i-1) The sum of the current discharge currents of the battery packs in the first i-1 online battery packs when in the discharge state.

[0115] Among them, the R d(i-1) The calculation formula is:

[0116] i≥2

[0117] In the discharge state, the preset range is set as above because: at the beginning, the voltage of the online battery pack is higher than that of the battery pack to be connected, which prevents the online battery pack from charging the battery pack to be connected while discharging the load, making the discharge of the online battery pack larger, so it is chosen not to connect the pack. The online battery pack needs to continue to discharge until it is lower than the voltage of the battery to be connected, and its voltage difference ∆U is greater than a certain value λ×I d(i-1) ×R d(i-1) (to prevent the battery pack to be incorporated from providing current to the load while charging the online battery pack), but it cannot exceed the maximum value Imaxd×R di , the packing operation can be carried out to ensure that the newly added battery pack can share part of the load discharge current, and there is no circulating current between the online battery pack and the battery pack to be added. After the addition, all online battery packs have discharge current. Different battery SOC, different temperature, and different health status values ​​(SOH) all have an impact on the maximum allowable charge and discharge current Imaxd.

[0118] The Imaxd satisfies:

[0119] Imaxd=Min{I dsg-SOCdi ×SOH i , I dsg-Tdi ×SOH i}

[0120] Among them, the SOH i is the health status value of the ith battery pack to be incorporated. dsg-SOCdi When the battery pack to be incorporated is in the discharge state, the discharge SOC current of the i-th battery pack to be incorporated is limited by the discharge SOC; the I dsg-Tdi When in the discharging state, the discharge temperature current of the i-th battery pack to be incorporated is limited by the discharge temperature.

[0121] It is worth noting that, in some embodiments, the open circuit voltage of each battery pack is obtained with sampling accuracy in step S1, and the proportionality coefficient is greater than twice the sampling accuracy.

[0122] Among them, the proportional coefficient λ needs to be at least twice greater than the sampling accuracy. This is because the error for the next battery pack is 1 sampling accuracy lower and the error for the previous battery pack is 1 sampling accuracy higher. Therefore, when setting the preset range, the error caused by the two sampling accuracy needs to be considered.

[0123] The specific value of the proportionality coefficient λ can be reasonably set according to the actual situation. For example, if the sampling accuracy is 1mV, and the voltage difference of each battery pack is 10V, then the proportionality coefficient λ>2×(1mV / 10V), that is, λ>0.0002. However, since the value of 0.0002 is very small, it may not be enough to provide sufficient safety margin in practical applications. Therefore, a slightly larger λ value can be selected. For example, λ=0.01 (or 1%, expressed as a percentage) can be selected.

[0124] (3) In some embodiments, when the battery pack is in a charging state, the formula of step S5 is:

[0125]

[0126] It should be noted that ∆U ci The voltage difference is obtained by subtracting the open circuit voltage of the i-th battery pack to be integrated from the open circuit voltage of the first i-1 online battery packs, that is, it is required that in the charging state, the open circuit voltage of the online battery pack should be increased to above the open circuit voltage of the battery pack to be integrated.

[0127] Among them, the ∆U ci is the voltage difference between the first i-1 online battery packs and the i-th battery pack to be incorporated in the charging state, the λ×I c(i-1) ×R c(i-1) and the Imaxc×R ci The preset range when the charging state is limited, wherein the λ is a proportionality coefficient, the Imaxc is the maximum allowable charging current of the i-th battery pack to be incorporated in the charging state, and the R c(i-1) is the resistance of the first i-1 online battery packs in the charging state, the R ci is the resistance of the ith battery pack to be incorporated in the charging state; c(i-1) The sum of the current charging currents of the battery packs in the first i-1 online battery packs when the battery pack is in the charging state.

[0128] Among them, the R c(i-1) The calculation formula is:

[0129] i≥2

[0130] In the charging state, the preset range is set as above because: at the beginning, the voltage of the online battery pack is lower than that of the battery pack to be integrated, so the battery pack to be integrated is prevented from charging the online battery pack (i.e., the battery pack to be integrated is discharged), so the online battery pack needs to continue to charge until it is higher than the voltage of the battery pack to be integrated, and its voltage difference ∆U is greater than a certain value λ×I c(i-1) ×R c(i-1), but cannot exceed the maximum value Imaxc×R ci , the battery pack can be combined to ensure that the battery pack to be combined can share part of the charging current, and there is no circulation between the online battery pack and the battery pack to be combined. After the combination, all online battery packs have charging current. Different battery SOC, different temperature, and different health status values ​​(SOH) all have an impact on the maximum allowable charging current Imaxc.

[0131] The Imaxc satisfies:

[0132] Imaxc=Min{I chg-SOCci ×SOH i , I chg-Tci ×SOH i}

[0133] Among them, the SOH i is the health status value of the ith battery pack to be incorporated. chg-SOCci When the charging state is the charging state, the charging SOC current of the i-th battery pack to be incorporated is limited by the charging SOC; the I chg-Tci When in the charging state, the charging temperature current of the i-th battery pack to be incorporated is limited by the discharge temperature.

[0134] It is worth noting that, in the charging state, the proportionality coefficient can refer to the above-mentioned discharge state, which will not be repeated here.

[0135] Step S6, controlling the battery pack to be incorporated to be incorporated with the online battery pack to obtain an incorporated battery.

[0136] When the voltage difference between the battery pack to be incorporated and the online battery pack is within a preset range, the battery pack to be incorporated and the online battery pack can be controlled to be incorporated in parallel, thereby achieving safe integration.

[0137] The battery pack to be incorporated is a battery pack that needs to be incorporated into the online battery pack. The battery to be incorporated refers to the battery pack to be incorporated and the online battery pack as a whole.

[0138] It is worth noting that, no matter in the static state, the discharging state, or the charging state, when controlling the battery pack to be incorporated and the online battery pack to be combined, the online battery pack is controlled to be in the on state, the battery pack to be incorporated is controlled to be in the on state, and the remaining battery packs in the battery pack are controlled to be in the off state. Then, by only controlling the battery pack to be incorporated to be in the on state, and the remaining battery packs to be in the off state, the battery pack to be incorporated and the online battery pack are combined to form the combined battery. There is no current interaction between the combined battery and the remaining battery packs, which can effectively reduce the safety hazards caused by the large voltage difference between the combined battery and the remaining battery packs, and can greatly reduce the power consumption loss caused by the mutual power replenishment between the combined battery and the remaining battery packs. This not only meets the user's needs to increase the available capacity of the battery pack by combining and expanding the capacity, but also meets the user's expectation for the longest possible service life of the battery pack.

[0139] Step S7, using the parallel-packed battery as the online battery pack, and repeating steps S4 and S5 until the voltage difference exceeds the preset range.

[0140] When the online battery pack and the battery pack to be merged are merged to form a merged battery, the merged battery is then used as the online battery pack. Then, when the subsequent battery pack to be merged meets the merge conditions in step S5, the merge operation is performed again, so that the battery packs that meet the merge conditions in step S5 among the multiple battery packs that need to be merged can be merged in sequence according to the sorting, thereby realizing the merge expansion of the battery pack.

[0141] In addition, for the static state or the discharge state, each battery pack is sorted in descending order according to the size of the open circuit voltage, that is, each battery pack is sequentially connected in order of the open circuit voltage from large to small. In the discharge state, as time goes by, the voltage difference of the online battery pack (in the open state) decreases due to the connection of the external load, so that the voltage difference between the battery pack to be incorporated (the battery pack to be connected) with a smaller open circuit voltage and the online battery pack is more likely to meet the connection condition set in the above step S5 (whether the voltage difference is within the preset range), that is, it is easier to achieve successful connection. In other words, the embodiment of the present application cleverly uses the voltage difference reduction in the discharge state and the order of connection time, so that in the discharge state, not only can the connection of as many battery packs as possible be achieved, but also the energy consumption caused by the mutual power replenishment between the battery packs in the online battery pack can be greatly reduced.

[0142] In addition, for the charging state, the battery packs in the battery pack are sorted in ascending order according to the size of the open circuit voltage, that is, the battery packs are sequentially connected in order of the open circuit voltage from small to large. In the charging state, as time goes by, the voltage difference of the online battery pack (in the open state) increases due to the connection to the external voltage, so that the voltage difference between the battery pack to be incorporated (the battery pack to be incorporated) with a larger open circuit voltage and the online battery pack is more likely to meet the packaging condition set in the above step S5 (whether the voltage difference is within the preset range), that is, it is easier to achieve successful packaging. In other words, the embodiment of the present application cleverly uses the increase in the voltage difference in the charging state and the order of the packaging time, so that in the charging state, not only can the packaging of as many battery packs as possible be achieved, but also the energy consumption caused by the mutual power replenishment between the battery packs in the online battery pack is greatly reduced.

[0143] By choosing not to combine the batteries when the voltage difference is large, and combining the batteries when the voltage of the online battery pack and the battery pack to be combined are close after the system is connected to charge or discharge, the existing technology avoids the use of other methods such as Buck circuits to forcibly level the voltage difference between the battery packs (between the online battery pack and the battery pack to be combined), saving hardware costs and making the hardware circuit more flexible and simple in solution design. This solution can also get rid of the limitations of using MOS tubes, such as using high-voltage systems that use relays as charging and discharging switches or other switch device designs for combined systems.

[0144] By considering the real-time current under different working conditions (stationary state, charging state, discharging state), the resistance of the online battery pack, the maximum allowable charge / discharge current of the battery pack to be integrated, and the resistance of the battery pack to be integrated, the current state of the battery pack can be judged more accurately, and the real-time and accurate allowable voltage difference range for integration (ie: preset range) can be obtained, making the integration process safer.

[0145] In order to facilitate readers to understand the inventive concept of the present application, examples are given of how to combine battery packs in a static state, a discharging state, and a charging state, taking the battery pack including at least three battery packs as an example.

[0146]

Standing state

[0147] In the static state, the battery pack with the largest open circuit voltage, i.e., the battery pack with serial number 1, is combined with the battery packs in the previous order, and its open tube is controlled for charging, while the remaining battery packs keep the MOS tubes (or other types of switches such as relays, etc.) closed. At this time, it is determined whether the voltage difference between the battery pack with the second highest open circuit voltage, i.e., the battery pack with serial number 2 (the battery pack to be combined) and the battery pack with the largest open circuit voltage (the battery pack in the previous order) is within the preset range. If so, that is, when the combination conditions are met, the charging and discharging tubes (or other types of switches such as relays) can be directly turned on for combination, and then the battery pack with serial number 3 is judged in the same way to determine whether the pressure difference allows combination, until a battery pack with a pressure difference that does not meet the combination conditions appears.

[0148] The static state and packaging process are as follows:

[0149] 1) When the battery packs are in a static state, the open circuit voltages are as follows: Figure 5 , the voltage satisfies U1>U2>U3.

[0150] like Figure 5 As shown, battery pack U1 is an online battery pack, which needs to be discharged to level the voltage difference when the packs are connected, and battery pack U2 is the next battery pack to be connected, which needs to be charged to level the voltage difference when the packs are connected.

[0151] Imaxs = Min{I chg-socs2 ×SOH2,I chg-Ts2 ×SOH2}.

[0152] 2) When the static state and inclusion conditions are met, the state is as follows Figure 6 shown.

[0153] like Figure 6 As shown, the pressure difference ∆Us2 between U1 and U2 satisfies ∆U s2 ≤I maxs ×R s2 The static state and packaging conditions can be met, and the tube can be opened and packaged directly at this time.

[0154] 3) After the package is combined, the status is as follows Figure 7 shown.

[0155] Figure 7 As shown in the figure, after the package is combined, the pressure difference between U1 and U2 will be leveled. At this time, the pressure difference between U2 (U1 and U2 are the same) and U3 is further determined, and it is known that ∆Us3≤Imaxs×R is not satisfied. s3 The inclusion condition is met, so the static state inclusion ends here.

[0156]

Discharge status

[0157] When the discharge is detected, the battery pack U1 with the highest open circuit voltage is used as the battery pack in the front of the above-mentioned sequence, and its open tube discharge is controlled. The remaining battery packs keep the MOS tubes (or other types of switches such as relays) turned off. As the discharge state progresses, the voltage of the battery pack in the front of the above-mentioned sequence decreases. At this time, it is determined whether the voltage difference between the battery pack with the second highest open circuit voltage, that is, the battery pack with serial number 2 (the battery pack to be merged) and the battery pack with the largest open circuit voltage (the battery pack in the front of the above-mentioned sequence) is within the preset range. If so, the conditions for parallel packing are met and the parallel packs can be directly paralleled. Then, the battery pack with serial number 3 is judged in the same way to determine whether the pressure difference allows the parallel packing, until a battery pack with a pressure difference that does not meet the parallel packing conditions appears.

[0158] The conditions for parallel packing in the discharge state are as follows:

[0159] like Figure 8 , U 1-discharge-t is the voltage sampled when the battery pack U1 is discharged at time t, ∆U is the difference between the voltage of U1 at time t and the voltage of the battery pack to be incorporated U2, I dt is the discharge current at the current moment, when only U1 is in the online battery pack.

[0160] Because U 1-discharge-t =U1-I dt R1, then ∆U d2 =U2-U 1-discharge-t .

[0161] The internal resistance of the parallel-packed battery is R= , that is, the total internal resistance will decrease. If the voltage difference between the two is equal, then U 1-discharge-t will rebound, causing U2 to still share the current with U1. To prevent the above situation from happening, U 1-charge-t The following conditions must be met before it can be included with U2:

[0162] (U1-I dt R1)+λI dt R1≤U2≤(U1-I dt R1)+I maxd R2

[0163] That is U 1-discharge-t +λI dt R1≤U2≤U 1-discharge-t +I maxd R2

[0164] Among them, R1=R2.

[0165] Where λ is the proportionality coefficient, λ needs to be at least twice greater than the sampling accuracy, and U2 needs to be greater than U 1-discharge-t Exceeding a value λI dtOnly when R1 is connected can it be ensured that U1 and U2 are discharged together after being connected, and U1 will not charge U2. (To prevent U1 from discharging to the external load and adding the burden of charging U2 at the same time).

[0166] Therefore, the packing condition in the above discharge process can be deduced as follows:

[0167] λ×I d(i-1) ×R d(i-1) ≤∆U di ≤Imaxd×R di

[0168] For the specific meaning of this formula, please refer to the above text and will not be repeated here.

[0169] The discharge process of multiple battery packs is as follows:

[0170] 1) Sample voltage of each battery pack before discharge Figure 5 , the voltage satisfies U1>U2>U3.

[0171] 2) The state when the discharge does not meet the package is as follows Fig. 9 .

[0172] like Fig. 9 , the voltage when U1 discharges is U 1-discharge-t , does not satisfy the formula U 1-discharge-t +λI dt R1≤U2≤U 1-discharge-t +I maxd R2, that is, the conditions for discharge and packaging are not met.

[0173] 3) During the discharge process, the state of the package is as follows Figure 8 .

[0174] like Figure 8 Before the battery packs are combined, the voltage of each battery pack is sampled as U 1-disharge-t and U2, let the voltage difference between the two battery packs be ∆U, ∆U satisfies the above formula U 1-discharge-t +λI dt R1≤U2≤U 1-discharge-t +I maxd R2 can be combined and packaged to obtain Fig.10 shown.

[0175] like Fig.10 After the battery pack U1 and battery pack U2 are combined, let U 1-disharge-t The voltage difference after merging with U2 is U d1-2 , because the voltage difference on the bus will be leveled after the open tube and the package are connected, the discharge voltage difference U can be calculated at this time d1-2 Equal to U 1-disharge-tand half of the sum of U2. Then we can calculate that: U d1-2 =U2-∆U / 2=U 1-discharge-t +∆U / 2=(U 1-discharge-t +U2) / 2≤U2-λI dt R1 / 2. At this time, the calculation is the instantaneous state of discharge and packing rather than the long-term state, so U2 is not counted as an online battery pack, and the discharge current I dt The internal resistance R does not change.

[0176] 4) The conditions for packaging continue to be met in the discharge state, such as Fig.11 shown.

[0177] like Fig.11 After the two battery packs U1 and U2 are put together for a period of time, U1 and U2 can be regarded as a whole. d1-2 =U3-∆U≤U3-λI dt R2, continue to meet the inclusion conditions.

[0178] To facilitate subsequent calculations, the lowest condition is taken, that is, the pressure difference is equal to the preset value: ∆U=λI dt R2. Let the voltage difference between U1-2 (U1 and U2 as a whole) and U3 be U d1-2-3 , because the voltage difference of the three battery packs will be leveled after the tubes are opened and packed together, such as Fig.12 , we can know that the charging voltage difference U sampled at this time d1-2-3 Equal to the voltage U of the two battery packs d1-2 and 1 / 3 of the sum of U3, and satisfying U d1-2-3 =(U3+2U d1-2 ) / 3=U d1-2 +λI dt R2 / 3.

[0179] Thereafter, the method of combining the battery packs in the discharged state is similar.

[0180]

Charging status

[0181] When charging is detected, refer to Fig.13 , the battery pack U1 with the lowest open circuit voltage is used as the battery pack in the front of the above-mentioned sequence, and its open tube discharge is controlled, and the remaining battery packs keep the MOS tubes (or other types of switches such as relays) closed. As the charging state progresses, the voltage difference of the battery pack in the front of the above-mentioned sequence decreases. At this time, it is determined whether the voltage difference between the battery pack with the second lowest open circuit voltage, that is, the battery pack with sequence number 2 (the battery pack to be merged) and the battery pack with the lowest open circuit voltage (the battery pack in the front of the above-mentioned sequence) is within the preset range. If so, the combination condition is met and the combination can be directly performed. Then, the battery pack with sequence number 3 is judged in this way to determine whether the pressure difference allows the combination, until a battery pack with a pressure difference that does not meet the combination condition appears.

[0182] The conditions for parallel packing in the charging state are as follows:

[0183] like Fig.14 , U 1-charge-t is the voltage sampled when the battery pack U1 is charged at time t, ∆U is the difference between the charging voltage of U1 at time t and the voltage of the battery pack to be incorporated U2, I ct is the charging current at the current moment, when only U1 is online in the battery pack.

[0184] Because U 1-charge-t =U1+I ct R1, then ∆U c2 =U 1-charge-t -U2.

[0185] The internal resistance of the battery after packaging is R= , that is, the total internal resistance will decrease. If the voltage difference between the two is equal, then U 1-charge-t will decrease, then U2 will still supply current to U1. 1-charge-t It must be greater than U2, that is, it can be included if the following conditions are met:

[0186] (U1+I ct R)-I maxc R2≤U2≤(U1+I ct R)-λI ct R1

[0187] That is U 1-charge-t -I maxc R2≤U2≤U 1-charge-t -λI ct R1

[0188] Where λ is the proportionality coefficient, λ needs to be at least twice greater than the sampling accuracy, and U2 needs to be greater than U 1-discharge-t Exceeding a value λI dt Only when R1 is connected can it be guaranteed that U1 and U2 are discharged together after being connected, and there will be no situation where U1 charges U2.

[0189] Therefore, the packing conditions in the above charging process can be deduced as follows:

[0190] λ×I c(i-1) ×R c(i-1) ≤∆U ci ≤Imaxc×R ci

[0191] For the specific meaning of this formula, please refer to the above text and will not be repeated here.

[0192] The charging process of multiple battery packs is as follows:

[0193] 1) Sample voltage of each battery pack before charging Fig.13 , the voltage meets U1 <U2<U3。

[0194] 2) When the charging is not sufficient and the package is not fully charged, the status is as follows Fig.15 .

[0195] like Fig.15 , the open circuit voltage of U1 when charging is U1-charge-t, which does not meet U 1-charge-t -I maxc R2≤U2≤U 1-charge-t -λI ct R1, that is, the charging and packing conditions are not met.

[0196] 3) The state of the package during charging is as follows Fig.14 .

[0197] like Fig.14 Before the battery pack is put into the same pack, the voltage difference of each battery pack is sampled as U 1-charge-t and U2, let the voltage difference between the two battery packs be ∆U, ∆U satisfies the above formula U 1-charge-t -I maxc R2≤U2≤U 1-charge-t -λI ct R1, after the package can be combined, the status after the package is combined is as follows Fig.16 shown.

[0198] like Fig.16 , after U1 and U2 are combined, let U 1-Charge-t The voltage after combining with U2 is U c1-2 , because the voltage on the bus will be leveled after the open tube and the package are connected, the charging voltage U can be calculated at this time c1-2 Equal to U 1-charge-t and half of the sum of U2. Then we can calculate that: U c1-2 =U2+∆U / 2=U 1-charge-t -∆U / 2=(U 1-Charge-t +U2) / 2≥λI ct R1 / 2+U2. At this time, the calculation is for the instantaneous state of charging and packing rather than the long-term state, so U2 is not counted as an online battery pack, and the charging current I ct The internal resistance R does not change.

[0199] 4) The conditions for packaging continue to be met during charging, such as Fig.17 shown.

[0200] like Fig.17 After the first two battery packs U1 and U2 are put together for a period of time, U1 and U2 can be regarded as a whole. c1-2 =∆U+U3≥λI ctR2+U3, continue to meet the inclusion conditions.

[0201] To facilitate subsequent calculations, the lowest condition is taken, that is, the pressure difference is equal to the preset value: ∆U=λI ct R2. Let the voltage of U1-2 (U1 and U2 as a whole) and U3 be U c1-2-3 , because the voltages of the three battery packs will be leveled after the tubes are opened and packed together, such as Fig.18 , we can know that the charging voltage U sampled at this time c1-2-3 Equal to the voltage U of the two battery packs c1-2 and 1 / 3 of the sum of U3, and satisfying U c1-2-3 =(2U c1-2 +U3) / 3=U c1-2 -λIctR2 / 3.

[0202] Thereafter, the method of combining the battery packs in the discharged state is similar.

[0203] In an embodiment of the present application, a method for combining battery packs includes: step S1, obtaining the open-circuit voltage of each of the battery packs; step S2, sorting each of the battery packs according to the size of the open-circuit voltage; step S3, controlling the battery pack in the front order to be in an open state to form an online battery pack, and controlling the remaining battery packs to be in a closed state; step S4, sequentially obtaining the voltage difference between the battery pack to be combined and the online battery pack, the battery pack to be combined being the battery pack in the rear order; step S5, judging whether the voltage difference is within a preset range, and if so, executing step S6; step S6, controlling the battery pack to be combined with the online battery pack to obtain a combined battery; step S7, taking the combined battery as the online battery pack, and repeating steps S4 and S5 until the voltage difference exceeds the preset range. Through the battery pack paralleling method, the battery packs are sorted according to the size of the open circuit voltage, and then paralleled according to the principle of similar voltage, which effectively reduces the safety hazards caused by the large voltage difference, and can greatly reduce the power consumption loss caused by the mutual power replenishment between the battery packs in the online battery pack, which not only meets the user's demand for parallel expansion to increase the available capacity of the battery pack, but also meets the user's expectation of the longest possible service life of the battery pack. In addition, when paralleling the battery pack, a step of judging whether the voltage difference is within a preset range is introduced. When the voltage difference is within the preset range, the paralleling operation is performed, thereby effectively preventing the generation of circulating current and improving the stability, safety and efficiency of the battery pack. It is also important that, since the principle of similar voltage is adopted for paralleling, there is no need to use, for example, a Buck circuit to level the voltage difference between the battery packs (between the online battery pack and the battery pack to be incorporated), which saves hardware costs and makes the hardware circuit more flexible and simple in the design of the solution.

[0204] Embodiment 4

[0205] The following is a discussion of the battery pack assembly system provided in the embodiment of the present application. Fig.19 , Fig.19 1 is a schematic diagram of a battery pack paralleling system provided in an embodiment of the present application, wherein the battery pack paralleling system 1 comprises a first acquisition module 11, for acquiring the open circuit voltage of each of the battery packs; a sorting module 12, for sorting each of the battery packs according to the size of the open circuit voltage; a first paralleling module 13, for controlling the battery pack in the front order to be in an open state to form an online battery pack, and controlling the remaining battery packs to be in a closed state; a second acquisition module 14, for sequentially acquiring the voltage difference between the battery pack to be incorporated and the online battery pack, wherein the battery pack to be incorporated is the battery pack in the rear order; a judgment module 15, for judging whether the voltage difference is within a preset range, and if so, entering the second paralleling module 16; the second paralleling module 16, for controlling the battery pack to be incorporated to be paralleled with the online battery pack to obtain a paralleled battery; a third paralleling module 17, for treating the paralleled battery as the online battery pack, and repeatedly executing the second acquisition module 14 and the judgment module 15 until the voltage difference exceeds the preset range.

[0206] In some embodiments, the sorting module 12 is specifically used to sort the battery packs in descending order according to the size of the open circuit voltage when the battery packs are in a static state or a discharging state, and the battery pack in the front of the sorting has the largest open circuit voltage.

[0207] In some embodiments, the battery pack is in a static state, and the calculation logic of the judgment module 15 is:

[0208] ∆U si ≤Imaxs×R si

[0209] Among them, the ∆U si is the voltage difference between the first i-1 online battery packs and the i-th battery pack to be incorporated in the static state, and the Imaxs×R si is the preset range in the static state, wherein Imaxs is the maximum allowable charging current of the ith battery pack to be incorporated in the static state, and R si is the resistance of the ith battery pack to be incorporated in the static state;

[0210] The Imaxs satisfy:

[0211] Imaxs=Min{I chg-socsi ×SOH i , I chg-Tsi ×SOH i}

[0212] Among them, the SOH i is the health status value of the i-th battery pack to be incorporated;

[0213] Among them, the I chg-socsi When in the static state, the charging SOC current of the i-th battery pack to be incorporated is limited by the charging SOC; the I chg-Tsi When in the stationary state, the charging temperature current of the i-th battery pack to be incorporated is limited by the charging temperature.

[0214] In some embodiments, the battery pack is in a discharging state, and the calculation logic of the judgment module 15 is:

[0215] λ×I d(i-1) ×R d(i-1) ≤∆U di ≤Imaxd×R di

[0216] Among them, the ∆U di is the voltage difference between the ith battery pack to be incorporated and the first i-1 online battery packs in the discharge state, the λ×I d(i-1) ×R d(i-1) and the Imaxd×R di The preset range in the discharge state is limited, wherein λ is a proportionality coefficient, Imaxd is the maximum allowable discharge current of the ith battery pack to be incorporated in the discharge state, and R d(i-1) is the resistance of the first i-1 online battery packs in the discharge state, and the R di is the resistance of the ith battery pack to be incorporated in the discharge state; d(i-1) The sum of the current discharge currents of the battery packs in the first i-1 online battery packs when in the discharge state.

[0217] In some embodiments, the Imaxd satisfies:

[0218] Imaxd=Min{I dsg-SOCdi ×SOH i , I dsg-Tdi ×SOH i}

[0219] Among them, the SOH i is the health status value of the i-th battery pack to be incorporated;

[0220] Among them, the I dsg-SOCdi When the battery pack to be incorporated is in the discharge state, the discharge SOC current of the i-th battery pack to be incorporated is limited by the discharge SOC; the I dsg-TdiWhen in the discharging state, the discharge temperature current of the i-th battery pack to be incorporated is limited by the discharge temperature.

[0221] In some embodiments, the first acquisition module 11 has sampling accuracy when acquiring the open circuit voltage of each of the battery packs, and the proportionality coefficient λ is greater than twice the sampling accuracy.

[0222] In some embodiments, the sorting module 12 is specifically used to sort the battery packs in ascending order according to the size of the open circuit voltage when the battery packs are in a charging state, and the open circuit voltage of the battery pack in the front order is the smallest.

[0223] In some embodiments, the battery pack is in a charging state, and the calculation logic of the judgment module 15 is:

[0224] λ×I c(i-1) ×R c(i-1) ≤∆U ci ≤Imaxc×R ci

[0225] Among them, the ∆U ci is the voltage difference between the first i-1 online battery packs and the i-th battery pack to be incorporated in the charging state, the λ×I c(i-1) ×R c(i-1) and the Imaxc×R ci The preset range when the charging state is limited, wherein the λ is a proportionality coefficient, the Imaxc is the maximum allowable charging current of the i-th battery pack to be incorporated in the charging state, and the R c(i-1) is the resistance of the first i-1 online battery packs in the charging state, the R ci is the resistance of the ith battery pack to be incorporated in the charging state; c(i-1) The sum of the current charging currents of the battery packs in the first i-1 online battery packs when the battery pack is in the charging state.

[0226] In some embodiments, the Imaxc satisfies:

[0227] Imaxc=Min{I chg-SOCci ×SOH i , I chg-Tci ×SOH i}

[0228] Among them, the SOH i is the health status value of the i-th battery pack to be incorporated;

[0229] Among them, the I chg-SOCciWhen the charging state is the charging state, the charging SOC current of the i-th battery pack to be incorporated is limited by the charging SOC; the I chg-Tci When in the charging state, the charging temperature current of the i-th battery pack to be incorporated is limited by the charging temperature.

[0230] In the embodiment of the present application, the open circuit voltage of each battery pack is obtained by the first acquisition module 11; the sorting module 12 sorts each battery pack according to the size of the open circuit voltage; the first parallel pack module 13 controls the battery pack in the front to be in the open state to form an online battery pack, and controls the remaining battery packs to be in the closed state; the second acquisition module 14 sequentially obtains the voltage difference between the battery pack to be incorporated and the online battery pack, and the battery pack to be incorporated is the battery pack in the rear order; the judgment module 15 judges whether the voltage difference is within the preset range, and if so, enters the second parallel pack module 16; the second parallel pack module 16 controls the battery pack to be incorporated and the online battery pack to be incorporated. The online battery packs are combined to obtain combined batteries; the combined batteries are used as the online battery packs through the third combined module 17, and the second acquisition module 14 and the judgment module 15 are repeatedly executed until the voltage difference exceeds the preset range, then the battery packs are sorted according to the size of the open circuit voltage, and then combined according to the principle of similar voltage, which effectively reduces the safety hazards caused by the large voltage difference, and can greatly reduce the power consumption loss caused by the mutual power replenishment between the battery packs in the online battery pack. This not only meets the user's needs for combined expansion to increase the available capacity of the battery pack, but also meets the user's expectation of the longest possible service life of the battery pack. In addition, when combining the battery packs, a step of judging whether the voltage difference is within the preset range is also introduced. The combined operation is performed only when the voltage difference is within the preset range, thereby effectively preventing the generation of circulating current and improving the stability, safety and efficiency of the battery pack. It is also important to note that, since the principle of similar voltage is adopted for parallel connection, there is no need to use a separate Buck circuit to level the voltage difference between the battery packs (between the online battery pack and the battery pack to be connected), which saves hardware costs and makes the hardware circuit design more flexible and simple.

[0231] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for packing battery packs, characterized in that: Applied to multiple battery packs that need to be packed together, the method includes: Step S1, obtaining the open circuit voltage of each battery pack; Step S2, sorting the battery packs according to the open circuit voltage; when the battery packs are in a discharging state, sorting the battery packs in descending order according to the open circuit voltage, and the open circuit voltage of the battery pack in the front order is the largest; when the battery packs are in a charging state, sorting the battery packs in ascending order according to the open circuit voltage, and the open circuit voltage of the battery pack in the front order is the smallest; Step S3, controlling the battery pack in the front order to be in an on state to form an online battery pack, and controlling the other battery packs to be in an off state; Step S4, sequentially obtaining the voltage difference between the battery pack to be incorporated and the online battery pack, wherein the battery pack to be incorporated is the battery pack in the later order; Step S5, determining whether the pressure difference is within a preset range, if so, executing step S6; Step S6, controlling the battery pack to be incorporated to be incorporated with the online battery pack to obtain an incorporated battery; Step S7, using the parallel-packed battery as the online battery pack, and repeating steps S4 and S5 until the voltage difference exceeds the preset range; The preset range in step S5 is obtained according to the product of the resistance of the online battery pack and the current charge / discharge current, and the product of the maximum allowable charge / discharge current and the resistance of the battery pack to be incorporated; When the battery pack is in a discharging state, the formula of step S5 is: λ×I d(i-1) ×R d(i-1) ≤ ∆U di ≤ Imaxd×R di Among them, the ∆U di is the voltage difference between the ith battery pack to be incorporated and the first i-1 online battery packs in the discharge state, the λ×I d(i-1) ×R d(i-1) and the Imaxd×R di The preset range in the discharge state is limited, wherein λ is a proportionality coefficient, Imaxd is the maximum allowable discharge current of the ith battery pack to be incorporated in the discharge state, and R d(i-1) is the resistance of the first i-1 online battery packs in the discharge state, and the R di is the resistance of the ith battery pack to be incorporated in the discharge state; d(i-1) The sum of the current discharge currents of the battery packs in the first i-1 online battery packs when in the discharge state; When the battery pack is in a charging state, the formula of step S5 is: λ×I c(i-1) ×R c(i-1) ≤ ∆U ci ≤ Imaxc×R ci Among them, the ∆U ci is the voltage difference between the first i-1 online battery packs and the i-th battery pack to be incorporated in the charging state, the λ×I c(i-1) ×R c(i-1) and the Imaxc×R ci The preset range when the charging state is limited, wherein the λ is a proportionality coefficient, the Imaxc is the maximum allowable charging current of the i-th battery pack to be incorporated in the charging state, and the R c(i-1) is the resistance of the first i-1 online battery packs in the charging state, the R ci is the resistance of the ith battery pack to be incorporated in the charging state; c(i-1) The sum of the current charging currents of the battery packs in the first i-1 online battery packs when the battery pack is in the charging state.

2. The method according to claim 1, characterized in that The step S2 comprises: When the battery packs are in a static state, the battery packs are sorted in descending order according to the magnitude of their open circuit voltages, and the battery packs in the front order have the largest open circuit voltage.

3. The method according to claim 2, characterized in that When the battery pack is in a static state, the formula of step S5 is: ∆U si ≤ Imaxs×R si Among them, the ∆U si is the voltage difference between the first i-1 online battery packs and the i-th battery pack to be incorporated in the static state, and the Imaxs×R si is the preset range in the static state, wherein Imaxs is the maximum allowable charging current of the ith battery pack to be incorporated in the static state, and R si is the resistance of the ith battery pack to be incorporated in the static state; The Imaxs satisfy: Imaxs = Min{I chg-socsi ×SOH i ,I chg-Tsi ×SOH i } Among them, the SOH i is the health status value of the i-th battery pack to be incorporated; Among them, the I chg-socsi In the static state, the charging SOC current of the i-th battery pack to be incorporated is limited by the charging SOC; I chg-Tsi When in the stationary state, the charging temperature current of the i-th battery pack to be incorporated is limited by the charging temperature.

4. The method according to claim 1, characterized in that The Imaxd satisfies: Imaxd=Min{I dsg-SOCdi ×SOH i ,I dsg-Tdi ×SOH i } Among them, the SOH i is the health status value of the i-th battery pack to be incorporated; Among them, the I dsg-SOCdi In the discharging state, the discharge SOC current of the i-th battery pack to be incorporated is limited by the discharge SOC; I dsg-Tdi When in the discharging state, the discharge temperature current of the i-th battery pack to be incorporated is limited by the discharge temperature.

5. The method according to claim 1, characterized in that: The Imaxc satisfies: Imaxc = Min{I chg-SOCci ×SOH i ,I chg-Tci ×SOH i } Among them, the SOH i is the health status value of the i-th battery pack to be incorporated; Among them, the I chg-SOCci When the battery is in the charging state, the charging SOC current of the i-th battery pack to be incorporated is limited by the charging SOC; I chg-Tci When in the charging state, the charging temperature current of the i-th battery pack to be incorporated is limited by the charging temperature.

6. The method according to claim 1, characterized in that The open circuit voltage of each battery pack is obtained with sampling accuracy in step S1, and the proportionality coefficient is greater than twice the sampling accuracy.

7. A battery pack packaging system, characterized in that: Applicable to multiple battery packs that need to be packed together, the system includes: A first acquisition module, used to acquire the open circuit voltage of each battery pack; A sorting module, used for sorting each of the battery packs according to the size of the open circuit voltage; when the battery packs are in a discharging state, sorting each of the battery packs in descending order according to the size of the open circuit voltage, and the open circuit voltage of the battery pack in the front order is the largest; when the battery packs are in a charging state, sorting each of the battery packs in ascending order according to the size of the open circuit voltage, and the open circuit voltage of the battery pack in the front order is the smallest; The first packing module is used to control the battery pack in the front sequence to be in the on state to form an online battery pack, and control the other battery packs to be in the off state; A second acquisition module is used to sequentially acquire the voltage difference between the battery pack to be incorporated and the online battery pack, wherein the battery pack to be incorporated is the battery pack that is sorted later; A judging module, used for judging whether the pressure difference is within a preset range, and if so, entering the second packaging module; A second packing module, used for controlling the battery pack to be incorporated to be packed together with the online battery pack to obtain a packed battery; A third parallel packing module, used for taking the parallel packing battery as the online battery pack, and repeatedly executing the second acquisition module and the judgment module until the voltage difference exceeds the preset range; The preset range in the judgment module is obtained according to the product of the resistance of the online battery pack and the current charge / discharge current, and the product of the maximum allowable charge / discharge current and the resistance of the battery pack to be incorporated; When the battery pack is in a discharging state, the formula of the judgment module is: λ×I d(i-1) ×R d(i-1) ≤ ∆U di ≤ Imaxd×R di Among them, the ∆U di is the voltage difference between the ith battery pack to be incorporated and the first i-1 online battery packs in the discharge state, the λ×I d(i-1) ×R d(i-1) and the Imaxd×R di The preset range in the discharge state is limited, wherein λ is a proportionality coefficient, Imaxd is the maximum allowable discharge current of the ith battery pack to be incorporated in the discharge state, and R d(i-1) is the resistance of the first i-1 online battery packs in the discharge state, and the R di is the resistance of the ith battery pack to be incorporated in the discharge state; d(i-1) The sum of the current discharge currents of the battery packs in the first i-1 online battery packs when in the discharge state; When the battery pack is in a charging state, the formula of the judgment module is: λ×I c(i-1) ×R c(i-1) ≤ ∆U ci ≤ Imaxc×R ci Among them, the ∆U ci is the voltage difference between the first i-1 online battery packs and the i-th battery pack to be incorporated in the charging state, the λ×I c(i-1) ×R c(i-1) and the Imaxc×R ci The preset range when the charging state is limited, wherein the λ is a proportionality coefficient, the Imaxc is the maximum allowable charging current of the i-th battery pack to be incorporated in the charging state, and the R c(i-1) is the resistance of the first i-1 online battery packs in the charging state, the R ci is the resistance of the ith battery pack to be incorporated in the charging state; c(i-1) The sum of the current charging currents of the battery packs in the first i-1 online battery packs when the battery pack is in the charging state.

8. A battery pack packaging system, characterized in that: include: at least one processor; as well as A memory, wherein the memory is communicatively connected to the at least one processor, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the steps of the method according to any one of claims 1 to 6.

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