Parallel operation charging method for multiple battery packs, battery management system and battery

Abstract

The parallel operation charging method for the multiple battery packs comprises the steps that the current difference value between the allowable charging current and the actual charging current of each battery pack is obtained, a current difference value set is obtained, and the number of the current difference values in the current difference value set is defined as the first number; calculating a second number of the current difference values greater than or equal to the first current threshold value and a first ratio of the second number to the first number; in response to the first ratio being greater than or equal to the first percentage, requesting to increase the total charging current of the plurality of battery packs at a first rate; wherein the first current threshold value is a positive number, the total charging current is used for charging the multiple battery packs, and the first percentage is larger than or equal to 75% and smaller than or equal to 100%.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to a method for parallel charging of multiple battery packs, a battery management system, and a battery. Background Art

[0002] Multiple battery packs are connected in parallel in a battery device to increase the capacity and the endurance of the electrical device. For example, a battery device that powers a two-wheeled vehicle uses multiple battery packs connected in parallel to increase the mileage of the two-wheeled vehicle.

[0003] In the process of providing charging service for battery equipment, multiple battery packs are charged in parallel. At present, the charging efficiency and charging effect of multiple battery packs in parallel are low. Summary of the invention

[0004] In view of this, some embodiments of the present application provide a parallel charging method for multiple battery packs, a battery management system, a battery device and an electrical device, wherein the parallel charging method improves the charging efficiency and the charging effect.

[0005] In a first aspect, some embodiments of the present application provide a method for parallel charging of multiple battery packs, first obtaining the current difference between the allowed charging current and the actual charging current of each battery pack to obtain a current difference set, and defining the number of current differences in the current difference set as a first number. Then, a second number whose current difference is greater than or equal to a first current threshold value, and a first ratio of the second number to the first number are calculated. Next, in response to the first ratio being greater than or equal to a first percentage, a request is made to increase the total charging current of the multiple battery packs at a first rate; wherein the first current threshold value is a positive number, the total charging current is used to charge the multiple battery packs, and 75% ≤ the first percentage ≤ 100%.

[0006] In the above embodiment, the current difference is greater than or equal to the first current threshold value which is a positive number, indicating that the corresponding battery pack is being charged with a smaller current which is lower than its own allowable charging current, and has a lower charging efficiency. Based on this, it is monitored that the battery packs whose number accounts for the first percentage have a lower charging efficiency, and a request is made to increase the total charging current of multiple battery packs at a first rate, so that the charging current of each battery pack increases smoothly, which is beneficial to improving the charging efficiency. In addition, when 75%≤first percentage≤100%, that is, when the number of battery packs with low charging efficiency is monitored to reach the range [75%,100%], a request is made to increase the total charging current, which is beneficial to reducing the overcharging phenomenon caused by the charging current of a certain battery pack being greater than or equal to its own allowable charging current. In addition, compared with requesting the total charging current to jump directly to a large current value, requesting to increase the total charging current at the first rate reduces the risk of overcharging and overcurrent protection, which is beneficial to each battery pack being smoothly fully charged with a higher charging efficiency, and has a good charging effect. That is, the parallel charging method not only improves the charging efficiency, but also reduces the charging termination of the battery pack due to overcurrent protection, thereby improving the charging effect of multiple battery packs.

[0007] In some embodiments, in response to the total charging current increasing, a request is made to reduce the first rate. Based on the total charging current increasing at the first rate, as the total charging current increases, a request is made to reduce the first rate so that the increment of the total charging current gradually slows down. In this way, the charging current of each battery pack increases smoothly, which is beneficial to reducing overcharging and overcurrent protection, and improving charging efficiency and charging effect.

[0008] In some embodiments, the minimum value in the current difference is positively correlated with the first rate. In this embodiment, the minimum value in the current difference is a positive number, indicating that the actual charging current of the corresponding battery pack is closest to the allowed charging current, and the battery pack has a relatively large tendency to have overcurrent protection. Therefore, taking the battery pack with the greatest tendency to have overcurrent protection as a benchmark, it is determined that the first rate is positively correlated with its current difference, so that the first rate is conducive to reducing overcharging and overcurrent protection, and improving charging efficiency and charging effect.

[0009] In some embodiments, 85%≤first percentage≤100%. That is, when it is detected that the number of battery packs with low charging efficiency reaches the range [85%, 100%], a request is made to increase the total charging current at the first rate, which is beneficial to reduce overcharging and overcurrent protection, so that multiple battery packs are fully charged smoothly with higher charging efficiency.

[0010] In some embodiments, the method includes: calculating a third number whose current difference is greater than or equal to a second current threshold, and a second ratio of the third number to the first number. In response to the second ratio being greater than or equal to a second percentage, requesting to increase the total charging current of the plurality of battery packs at a second rate. The second current threshold is a positive number, the second current threshold is less than the first current threshold, the second rate is less than the first rate, and 50% ≤ the second percentage ≤ 100%.

[0011] In this embodiment, based on the fact that the second current threshold is less than the first current threshold and the second rate is less than the first rate, it can be seen that the stage of requesting to increase the total charging current at the second rate is the slow rise stage, and the stage of requesting to increase the total charging current at the first rate is the fast rise stage. In this way, the total charging current is requested to be increased in two stages, each stage corresponds to a different rate and current threshold, the overcurrent risk is small in the slow rise stage, and the corresponding second percentage range is more relaxed, so that the charging efficiency and overcurrent risk can be effectively balanced.

[0012] In some embodiments, 70% ≤ the second percentage ≤ 100%. That is, when it is detected that the number of battery packs with slightly lower charging efficiency reaches the range [70%, 100%], a request is made to increase the total charging current at the second rate, which is beneficial to reducing overcharging and overcurrent protection, so that multiple battery packs are fully charged smoothly with higher charging efficiency.

[0013] In some embodiments, the method includes: in response to the maximum value of the absolute value of the current difference in the current difference set being less than or equal to a third current threshold, stopping increasing the total charging current of multiple battery packs; wherein the third current threshold is a positive number, the third current threshold is less than or equal to the first current threshold, or the third current threshold is less than or equal to the second current threshold.

[0014] In this embodiment, the maximum absolute value of the current difference indicates that the actual charging current of the corresponding battery pack differs the most from the allowed charging current, and the absolute value of the current difference of the battery pack is less than or equal to the third current threshold, indicating that the actual charging current of each battery pack is close to its own allowed charging current, achieving a higher charging efficiency. Therefore, the total charging current of the multiple battery packs is stopped from increasing to prevent overcharging.

[0015] In some embodiments, a fourth number whose current difference is less than or equal to a fourth current threshold and a third ratio of the fourth number to the first number are calculated; in response to the third ratio being greater than or equal to a third percentage, a request is made to reduce the total charging current of the plurality of battery packs at a third rate; wherein the fourth current threshold is a negative number, 0<third percentage≤20%.

[0016] In the above embodiment, the current difference is less than or equal to the fourth current threshold value which is a negative number, indicating that the corresponding battery pack is charging with a current higher than its own allowable charging current, and has a tendency to cause overcurrent protection. Based on this, it is monitored that the battery packs whose number accounts for a third percentage have a tendency to cause overcurrent protection, and a request is made to reduce the total charging current of multiple battery packs at a third rate, so that the charging current of each battery pack decreases smoothly, which is beneficial to balance the charging efficiency and reduce overcurrent protection. In addition, 0<third percentage ≤20%, that is, it is monitored that the battery packs whose number accounts for (0,20%] have a tendency to cause overcurrent protection, and a request is made to reduce the total charging current, which is beneficial to reduce the problem of charging efficiency affected by overcurrent protection. In addition, compared with requesting the total charging current to jump directly to a small current value, requesting to reduce the total charging current at the third rate reduces the risk of overcurrent and ensures charging efficiency.

[0017] In some embodiments, in response to the total charging current decreasing, a request is made to reduce the third rate. Based on the total charging current decreasing at the third rate, as the total charging current decreases, the request is made to reduce the third rate so that the decrease in the total charging current gradually slows down. In this way, the charging current of each battery pack decreases smoothly, which is beneficial to reduce the risk of overcurrent while maintaining a high charging efficiency.

[0018] In some embodiments, the minimum value in the current difference is negatively correlated with the third rate. In this embodiment, the minimum value in the current difference is a negative number, indicating that the actual charging current of the corresponding battery pack exceeds the allowable charging current to the greatest extent, and the battery pack has a relatively large tendency to have overcurrent protection. Therefore, taking the battery pack with the greatest tendency to have overcurrent protection as a benchmark, it is determined that the third rate is negatively correlated with its current difference, that is, the smaller the minimum value in the current difference, the greater the degree of exceeding the allowable charging current, and the greater the third rate, so that the third rate quickly reduces the charging current, which is conducive to reducing overcurrent protection and maintaining a high charging efficiency.

[0019] In some embodiments, 0<third percentage≤10%. That is, it is monitored that the battery packs with a proportion in the range of (0,10%] have a tendency to cause overcurrent protection, and a request is made to reduce the total charging current at a third rate, which is conducive to reducing the problem of affecting charging efficiency due to overcurrent protection.

[0020] In some embodiments, a fifth number whose current difference is less than or equal to a fifth current threshold and a fourth ratio of the fifth number to the first number are calculated; in response to the fourth ratio being greater than or equal to a fourth percentage, a request is made to reduce the total charging current of the plurality of battery packs at a fourth rate; wherein the fifth current threshold is a negative number, the fifth current threshold is greater than the fourth current threshold, the fourth rate is less than the third rate, and 0<fourth percentage≤30%.

[0021] In this embodiment, based on the fact that the fifth current threshold is greater than the fourth current threshold and the fourth rate is less than the third rate, it can be seen that the stage of requesting to reduce the total charging current at the fourth rate is the slow decline stage, and the stage of requesting to reduce the total charging current at the third rate is the fast decline stage. In this way, the total charging current is requested to be reduced in two stages, each stage corresponds to a different rate and current threshold, the overcurrent risk is small in the slow decline stage, and the corresponding fourth percentage range is more relaxed, so that the charging efficiency and overcurrent risk can be effectively balanced.

[0022] In some embodiments, 0<the fourth percentage≤15%. That is, when it is detected that the number of battery packs with a slightly lower tendency to overcurrent protection reaches the range (0,15%], a request is made to reduce the total charging current at the fourth rate, which is beneficial to balance the charging efficiency and reduce the overcurrent protection.

[0023] In some embodiments, the method includes: in response to the maximum value of the absolute value of the current difference in the current difference set being less than or equal to a sixth current threshold, stopping reducing the total charging current of multiple battery packs; wherein the sixth current threshold is a positive number, the sixth current threshold is less than or equal to the absolute value of the fourth current threshold, or the sixth current threshold is less than or equal to the absolute value of the fifth current threshold.

[0024] In this embodiment, the maximum absolute value of the current difference indicates that the actual charging current of the corresponding battery pack has the largest difference with the allowed charging current. The absolute value of the current difference of the battery pack is less than or equal to the sixth current threshold, indicating that the actual charging current of each battery pack is close to its own allowed charging current, so that the overcurrent risk is reduced. Therefore, the total charging current of the multiple battery packs is stopped from being reduced to maintain a high charging efficiency.

[0025] In a second aspect, some embodiments of the present application provide a battery management system, including a processor and a memory, the memory being used to store instructions, and the processor being used to execute instructions, so as to implement the method for parallel charging of multiple battery packs in the first aspect.

[0026] In a third aspect, some embodiments of the present application provide a battery device, including a plurality of battery packs and a battery management system as in the second aspect.

[0027] In a fourth aspect, some embodiments of the present application provide an electrical device, including the battery device of the third aspect.

[0028] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1A is a schematic diagram of the structure of a battery device in some embodiments of the present application;

[0030] Figure 1B is a schematic diagram of the structure of a battery device in some embodiments of the present application;

[0031] Figure 2 is a schematic diagram of the structure of a battery pack in a battery device in some embodiments of the present application;

[0032] Figure 3 is a schematic diagram of the structure of a battery device and a charging device in some embodiments of the present application;

[0033] Figure 4 is a schematic diagram of the structure of a battery device and a charging device in some embodiments of the present application;

[0034] Figure 5 is a schematic diagram of the structure of a BMS in some embodiments of the present application;

[0035] Figure 6 is a schematic diagram of a charging and discharging circuit of a battery device in some embodiments of the present application;

[0036] Figure 7 is a schematic diagram of dynamically adjusting the total charging current in the parallel charging method in some embodiments of the present application;

[0037] Figure 8 is a schematic diagram of increasing the total charging current in the parallel charging method in some embodiments of the present application;

[0038] Fig. 9 is a schematic diagram of increasing the total charging current in the parallel charging method in some embodiments of the present application;

[0039] Fig.10 is a schematic diagram of reducing the total charging current in the parallel charging method in some embodiments of the present application;

[0040] Fig.11 is a schematic diagram of reducing the total charging current in the parallel charging method in some embodiments of the present application;

[0041] Fig.12 It is a schematic diagram of dynamically adjusting the total charging current in the parallel charging method of some embodiments of the present application. DETAILED DESCRIPTION

[0042] 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 described clearly and in detail in combination 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 the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0043] The technical features involved in the various embodiments of the present application described below do not conflict with each other and can be combined with each other.

[0044] Although the device schematic diagram is divided into functional modules and the flowchart shows a logical sequence, in some cases, the steps may be divided differently from the modules in the device or may be executed in an order different from that shown in the flowchart.

[0045] When an element is referred to as being “connected to” another element, it can be directly connected to the other element, or one or more intervening elements may be present therebetween.

[0046] The terms "first", "second", etc. in the specification and claims of this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0047] In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the previously and subsequently associated objects are in an "or" relationship.

[0048] When the battery device is provided with charging service, the battery device is electrically and communicatively connected with the charging device (such as a charging pile or a charger). The battery device sends a charging request to the charging device to charge with a total charging current, and the charging device responds to the charging request by providing a total charging current to charge multiple parallel battery packs in the battery device.

[0049] However, when the charging device provides the total charging current to multiple parallel battery packs, the actual charging current allocated to each battery pack is different, and it is easy for the actual charging current of some battery packs to be greater than their own allowable charging current, which may cause overcurrent protection. The charging of the battery pack that has overcurrent protection is interrupted in this charging service and cannot be fully charged, affecting the charging effect of the battery equipment.

[0050] In order to reduce overcurrent protection and improve charging effect, in some charging schemes, the charging equipment uses a smaller total charging current to charge multiple parallel battery packs. The actual charging current of each battery pack is less than or much less than its own allowable charging current, reducing the occurrence of overcurrent protection and ensuring that each battery pack is fully charged. However, this charging scheme has low charging efficiency and takes a long time to charge.

[0051] In order to improve charging efficiency, in some charging schemes, battery equipment uses the cumulative value of the allowable charging current of each battery pack or the product of the minimum allowable charging current in the battery pack and the number of battery packs as the total charging current. However, due to the different aging, temperature or internal resistance of each battery pack, some battery packs will still receive more current than their own allowable charging current, which is easy to trigger charging overcurrent protection, while some battery packs will receive less current than their own allowable charging current, resulting in lower charging efficiency.

[0052] Based on this, some embodiments of the present application provide a parallel charging method for multiple battery packs, a battery management system, a battery device and an electrical device. The parallel charging method is executed by the battery management system, so that the charging efficiency and charging effect of the battery device can be improved.

[0053] Based on the application of a battery management system (BMS) to battery equipment, in order to facilitate understanding of the role of the battery management system in the battery equipment, here, the structure of the battery equipment in some embodiments of the present application is first introduced.

[0054] Battery Equipment

[0055] Some embodiments of the present application provide a battery device 100, see Figure 1A The battery device 100 includes a plurality of battery packs 10 connected in parallel, for example, N battery packs 10 connected in parallel, namely, battery pack 1 to battery pack N, wherein N is an integer ≥ 2. Each battery pack 10 is an energy module of the battery device 100 to increase the capacity and endurance of the battery device 100.

[0056] In some embodiments, the positive terminal of each battery pack 10 is electrically connected to the positive port of the battery device 100 through a connector or a connecting harness, and the negative terminal of each battery pack 10 is electrically connected to the negative port of the battery device 100 through a connector or a connecting harness. It can be understood that in this embodiment, the charge and discharge ports of the battery device 100 are the same, and accordingly, the charge and discharge terminals of the battery pack 10 are the same.

[0057] In other embodiments, the charging and discharging ports of the battery device 100 are not completely the same, and accordingly, the charging and discharging terminals of the battery pack 10 are also not completely the same. Figure 1B , the battery device 100 includes a charging positive terminal C+, a discharging positive terminal P+, and a charging and discharging negative terminal P-(C-), and the battery pack 10 includes a charging positive terminal C+, a discharging positive terminal P+, and a charging and discharging negative terminal P-(C-). In the present application, each battery pack 10 can be connected in parallel without any restrictions on the charging and discharging ports or terminals.

[0058] In some embodiments, see Figure 2Each battery pack 10 includes a battery cell module 11 , a switch unit 12 and a battery management system (BATTERY MANAGEMENT SYSTEM, BMS) 13 .

[0059] The cell module 11 includes a plurality of cells, which are connected in series, in parallel or in a mixed connection. The mixed connection of the plurality of cells means that the electrical connection of the cells includes both series connection and parallel connection.

[0060] The switch unit 12 is connected in series to the positive terminal side or the negative terminal side of the cell module 11 to control the charge / discharge of the cell module 11. In some embodiments, the switch unit 12 is a mechanical switch or a semiconductor switch. In detail, the switch unit 12 includes: a charging switch element that is controlled to be turned on when charging; and a discharging switch element that is controlled to be turned on when discharging. However, this is only an example, and therefore, the switch unit 12 is not limited to MOSFET, etc., but a relay, etc. may be used instead.

[0061] The BMS 13 is connected to the cell module 11 and monitors data such as voltage, current, temperature, etc. of the cell module 11. Exemplarily, when the switch unit 12 is a semiconductor switch element, the BMS 13 measures or calculates the voltage and current of the gate, source, and drain of the semiconductor switch device.

[0062] In some embodiments, the current, voltage, temperature, etc. of the cell module 11 are measured using various sensors 14 disposed adjacent to the switch unit 12. As an input interface for receiving the measured values ​​of the above-mentioned various parameters, the BMS 13 includes a plurality of terminals and circuits connected to these terminals to process the input values. In addition, in some embodiments, the BMS 13 controls the on / off of the switch unit 12 and can be connected to the cell module 11 to monitor the status of the cell module 11.

[0063] The parameters such as current, voltage, temperature, etc. obtained as described above can be used by the BMS 13 to determine the allowable charging current and overcurrent protection threshold of the battery pack 10 to help determine the total charging current of the battery device 100 .

[0064] The BMSs 13 on each battery pack 10 are connected to each other in communication, and each BMS 13 is connected to each other in communication via a communication bus. Through the communication bus, each battery pack 10 can exchange charging state parameters (such as the above-mentioned allowable charging current and overcurrent protection threshold) and the like.

[0065] In some embodiments, see Figure 3When the battery device 100 is provided with charging service, the charging port of the battery device 100 is electrically connected to the charging device 200, and the battery device 100 is communicatively connected to the charging device 200. In some embodiments, the charging device 200 is connected to the communication bus 20 of the battery device 100 through a connection port or a communication line, so that the charging device 200 is communicatively connected to the BMS 13 of each battery pack 10 through the communication bus 20.

[0066] Among them, the communication bus 20 is such as a CAN communication bus, an RS485 communication bus, etc. In addition, each BMS13 and the charging device 200 and the BMS13 can also be connected to each other through other wired or wireless methods, such as through Wi-Fi communication, mobile communication technology or Bluetooth communication technology.

[0067] Based on the communication connection between each battery pack 10, each battery pack 10 is in communication connection with the charging device 200, and any battery pack 10 is defined as the master battery pack, and the other battery packs are slave battery packs. On the communication bus 20, the charging device 200 responds to the message sent by the BMS13 of the master battery pack. In this embodiment, the BMS13 of each slave battery pack sends the above-mentioned charging state parameters (such as the allowed charging current and the overcurrent protection threshold) to the BMS13 of the master battery pack. The BMS13 of the master battery pack determines the total charging current based on the charging state parameters of each battery pack 10, and sends a charging request to the charging device 200 to charge with the total charging current. The charging device 200 responds to the charging request flow to provide a total charging current to charge multiple parallel battery packs 10 in the battery device 100.

[0068] In some embodiments, see Figure 4 The battery device 100 further includes a main BMS 14, which is connected to the BMS 13 of each battery pack 10 in communication, and the main BMS 14 is connected to the charging device 200 in communication. The main BMS 14 receives the charging state parameters sent by the BMS 13 of each battery pack 10, determines the total charging current based on the charging state parameters, and sends a charging request to the charging device 200 to charge with the total charging current. In response to the charging request, the charging device 200 provides the total charging current to charge the multiple parallel battery packs 10 in the battery device 100.

[0069] The battery device 100 in the present application improves the parallel charging method of multiple battery packs 10 executed by BMS13 in the battery pack 10 or the main BMS14, so that BMS13 or the main BMS14 determines and adjusts the total charging current based on the actual situation of each battery pack 10, thereby improving the charging efficiency and charging effect.

[0070] Hereinafter, the BMS13 or the main BMS14 and the parallel charging method of multiple battery packs executed by the BMS13 or the main BMS14 will be described in detail. It is understood that in an embodiment including the main BMS14, the BMS13 and the main BMS14 have the same hardware structure, and the parallel charging method of multiple battery packs is executed by the main BMS14. In an embodiment not including the main BMS14, the parallel charging method of multiple battery packs is executed by the BMS13 of the battery pack.

[0071] Battery Management System

[0072] Some embodiments of the present application provide a battery management system. Figure 5 The battery management system 13 includes a memory 131 , a processor 132 , and a computer program stored in the memory 131 and executable on the processor 132 .

[0073] In some embodiments, the processor 132 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

[0074] The memory 131 may include a read-only memory (ROM), a random access memory 131 (RAM), a magnetic disk storage medium device, an optical storage medium device, a flash memory device, an electrical, optical or other physical / tangible memory 131 storage device. Therefore, generally, the memory 131 includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer executable instructions, and when the software is executed (e.g., by one or more processors 132), it is operable to perform the method for parallel charging of multiple battery packs described below with reference to the following.

[0075] The processor 132 runs a computer program corresponding to the executable program code by calling the executable program code stored in the memory 131 to implement the parallel charging method for multiple battery packs described below.

[0076] The BMS 13 may further include a communication unit 133 and a bus 134. Figure 5 As shown, the memory 131, the processor 132, and the communication unit 133 are connected through the bus 134 and communicate with each other. The communication unit 133 is mainly used to realize the communication between the modules, devices, units and / or devices in the embodiment of the present application. The input device and / or output device can also be accessed through the communication unit 133.

[0077] The bus 134 includes hardware, software, or both, coupling the components of the BMS 13 to each other. By way of example and not limitation, the bus 134 may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hyper Transport (HT) interconnect, an Industrial Standard Architecture (ISA) bus, an InfiniBand interconnect, a Low Pin Count (LPC) bus, a Memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VLB) bus, or other suitable buses or a combination of two or more of the above. Where appropriate, the bus may include one or more buses. Although embodiments of the present application describe and illustrate a particular bus, the present application contemplates any suitable bus or interconnect.

[0078] It should be noted that although the above BMS13 only shows the memory 131, the processor 132, and the communication unit 133, in the specific implementation process, those skilled in the art should understand that the BMS13 may also include other devices necessary for normal operation. At the same time, according to specific needs, those skilled in the art should understand that the BMS13 may also include hardware devices for implementing other additional functions. In addition, those skilled in the art should understand that the BMS13 may also include only the devices necessary for implementing the embodiments of the present application, and does not necessarily include Figure 5 All devices shown in .

[0079] The above article introduces the hardware basis of BMS. The following article introduces the method of BMS executing parallel charging of multiple battery packs.

[0080] How to charge multiple battery packs in parallel

[0081] The parallel charging method for multiple battery packs provided in the embodiment of the present application is implemented in a BMS having the above hardware structure. The BMS is the BMS of the above main battery pack, or the above BMS. The following is an exemplary description of the implementation of the above method by the BMS of the main battery pack. The BMS described in the following embodiments is the BMS of the main battery pack.

[0082] In the embodiment of the present application, after the battery device is electrically and communicatively connected to the charging device, the charging circuit of the battery device is turned on and the charging operation begins.

[0083] For example, Figure 6 As shown, the charge and discharge circuit of the battery device 100 includes a charge switch CHG1 and a discharge switch DSG1 connected in series. As a specific embodiment, the charge switch CHG1 and the discharge switch DSG1 can be field effect transistors, the charge switch CHG1 includes a body diode D1, and the discharge switch DSG1 includes a body diode D2. In some other embodiments, the charge switch CHG1 is connected in parallel with a diode D1, and the discharge switch DSG1 is connected in parallel with a diode D2, and the diode D1 and the diode D2 share a common cathode. The charge switch CHG1, the discharge switch DSG1, the diode D1 and the diode D2 can be used as part of the charge and discharge circuit, and the charge switch CHG1 and the discharge switch DSG1 are used to control the working state of the charge and discharge circuit.

[0084] In some embodiments, after the positive and negative ports of the battery device 100 are electrically connected to the positive and negative ports of the charging device, the voltage of the positive port of the battery device 100 increases. When the BMS detects that the voltage of the positive port increases and that the battery device is not fully charged, the BMS controls the charging switch CHG1 to close and the discharging switch DSG1 to start the charging operation. The current direction is: the positive port of the charging device → the positive port of the battery device → the discharging switch DSG1 → the charging switch CHG1 → the positive terminal of the parallel battery pack → the negative terminal of the parallel battery pack → the negative port of the battery device → the negative port of the charging device.

[0085] After the battery device starts charging, the charging device provides a total charging current to charge multiple battery packs. The BMS of each battery pack obtains the actual charging current. Taking the No. 2 battery pack as an example, the actual charging current is the charging current actually allocated to the No. 2 battery pack in this charging operation, which is collected by the BMS of the No. 2 battery pack; the allowable charging current is determined by the BMS of the No. 2 battery pack based on the temperature, charge state (SOC) or voltage of the No. 2 battery pack, combined with the power state (State of Power, SOP) table.

[0086] It is understandable that the BMS of the battery pack stores an SOP table, which contains the maximum charge and discharge power of the battery pack at different SOCs and different temperatures, such as the maximum charging power of 5s, 10s, 30s or 60s at different SOCs and different temperatures. Taking the maximum charging power of 60s as an example, the battery pack should be charged at a power not greater than the corresponding maximum charging power within 60s to ensure that it will not affect the life and use of the battery pack. Thus, the BMS of the battery pack can determine the maximum charging power based on the current SOC and the current temperature, and then determine the allowable charging current based on the maximum charging power and voltage. That is, under the current SOC and the current temperature, the actual charging current of the battery pack should preferably not exceed the allowable charging current. If the actual charging current of battery pack No. 2 exceeds the allowable charging current, it means that the current actual charging current is not friendly to battery pack No. 2, and battery pack No. 2 has a tendency to cause overcurrent protection.

[0087] Since the allowable charging current varies with the SOC and temperature of the battery pack, and the actual charging current varies with the aging degree, temperature or internal resistance of the battery pack, each battery pack BMS collects the actual charging current at a certain frequency or calculates the allowable charging current at a certain frequency. In some embodiments, the frequency of collecting the actual charging current is the same as the frequency of calculating the allowable charging current. Thus, the allowable charging current and the actual charging current of the battery pack can reflect its charging state.

[0088] Exemplarily, the current difference between the allowed charging current and the actual charging current reflects the charging state of the battery pack. Here, the current difference is equal to the allowed charging current minus the actual charging current. If the current difference is a positive number, it means that the actual charging current is less than the allowed charging current. Such charging is friendly to the battery pack and overcurrent protection will not occur. When the actual charging current is less than the allowed charging current to a certain extent, it means that the charging efficiency of the corresponding battery pack is low. If the current difference is a negative number, it means that the actual charging current is greater than the allowed charging current. Such charging is not friendly to the battery pack and has a tendency to cause overcurrent protection.

[0089] In some embodiments, based on the BMS communication connection of multiple battery packs in the battery device, the slave battery pack BMS sends its own allowed charging current and actual charging current to the master battery pack BMS, so that the master battery pack BMS obtains the allowed charging current and actual charging current of each battery pack, and then calculates the current difference corresponding to each battery pack. In some embodiments, the slave battery pack BMS sends the calculated current difference to the master battery pack BMS, so that the master battery pack BMS obtains the current difference corresponding to each battery pack.

[0090] like Figure 7As shown, the current differences corresponding to each battery pack constitute a current difference set. The main battery pack BMS defines the number of current differences in the current difference set as a first number. For example, if the number of battery packs is N, the first number is N, and N is a positive number greater than 1. The main battery pack BMS monitors the current difference set. If it is detected that a certain number of battery packs have a lower charging efficiency, it requests to increase the total charging current of the multiple battery packs. If it is detected that a certain number of battery packs have a tendency to have overcurrent protection, it requests to reduce the total charging current of the multiple battery packs. In this way, the total charging current is dynamically adjusted to improve the charging efficiency and charging effect of the battery equipment.

[0091] In some embodiments, a current threshold and a quantity percentage threshold are set to determine whether a certain quantity percentage of battery packs have a lower charging efficiency, thereby triggering a request to increase the total charging current.

[0092] like Figure 8 As shown, the main battery pack BMS calculates a second number whose current difference is greater than or equal to the first current threshold, and a first ratio of the second number to the first number. In response to the first ratio being greater than or equal to the first percentage, the main battery pack BMS requests to increase the total charging current at a first rate.

[0093] Among them, the first current threshold is the current threshold for monitoring low-efficiency charging, and the first current threshold is a positive number. In some embodiments, the first current threshold is 0.5A, 0.6A or 1A, etc. It is understandable that those skilled in the art can set the first current threshold according to the actual situation of the battery equipment. If the current difference is greater than or equal to the first current threshold, it means that the corresponding battery pack is charging with a smaller current that is lower than its own allowable charging current, and has a lower charging efficiency.

[0094] The first percentage is the threshold value for monitoring the proportion of inefficient charging. If the first ratio is greater than or equal to the first percentage, it means that the proportion of inefficiently charged battery packs has reached a certain proportion, and more battery packs have lower charging efficiency. Therefore, it is requested to increase the total charging current at a first rate to improve the charging efficiency. That is, it is monitored that the battery packs whose proportion reaches the first percentage have lower charging efficiency, and it is requested to increase the total charging current of multiple battery packs at the first rate, so that the charging current of each battery pack increases smoothly, which is conducive to improving the charging efficiency.

[0095] It is understandable that if the first percentage is too small, that is, a small number of battery packs with low charging efficiency are monitored, increasing the total charging current will easily cause the charging current of a certain battery pack to be greater than or equal to its own allowable charging current, resulting in overcharging and overcurrent protection. In some embodiments, 75% ≤ first percentage ≤ 100%. That is, when the number of battery packs with low charging efficiency is monitored to reach the range [75%, 100%], a request to increase the total charging current is beneficial to reduce the overcharging phenomenon caused by the charging current of a certain battery pack being greater than or equal to its own allowable charging current. In some embodiments, 85% ≤ first percentage ≤ 100%. That is, when the number of battery packs with low charging efficiency is monitored to reach the range [85%, 100%], a request to increase the total charging current at the first rate. In this embodiment, the first percentage is more cautious, which is beneficial to reduce overcharging and overcurrent protection, so that multiple battery packs can be fully charged smoothly with higher charging efficiency.

[0096] Among them, the first rate is the rate of increase of the total charging current, that is, the total charging current increases at the first rate. When the first ratio is monitored to be greater than or equal to the first percentage, the total charging current increases at the first rate. Compared with requesting the total charging current to directly jump to a large current value, requesting to increase the total charging current at the first rate reduces the risk of overcharging and overcurrent protection, which is conducive to each battery pack being fully charged smoothly with a higher charging efficiency and has a good charging effect. Based on the main battery pack BMS, the total charging current is sent to the charging device at a certain frequency, so that when the total charging current increases to the current sending time at the first rate, the increased total charging current is sent to the charging device at the current sending time.

[0097] Exemplarily, when the battery device starts charging, the main battery pack BMS determines that the total charging current I is the initial value linit, that is, I=linit; and sends the total charging current I to the charging device, requesting the charging device to provide the total charging current I to charge multiple battery packs. In some embodiments, the initial value linit is the minimum value of the allowable charging current of each battery pack; in some embodiments, the initial value linit is a fixed value, such as 2A or 3A. It can be seen that the initial value linit ensures that overcurrent protection does not occur during overcharging.

[0098] As charging proceeds, if it is detected at time t1 that the proportion of battery packs with lower charging efficiency reaches a first percentage, a request is made to increase the total charging current of the plurality of battery packs at a first rate. That is, the total charging current can be expressed by the following formula:

[0099] I′=I+V1*Δt

[0100] Wherein, I is the total charging current before increasing at the first rate, V1 is the first rate, Δt is the time for increasing the total charging current, and I′ is the total charging current after increasing at the first rate. In some embodiments, Δt=t-t1, t is the current moment, and t1 is the moment when the proportion of battery packs with lower charging efficiency detected reaches a first percentage.

[0101] It can be understood that the main battery pack BMS sends the total charging current I' at a first frequency, calculates whether the first ratio satisfies or is greater than or equal to the first percentage at a second frequency, and if so, still increases the total charging current at the first rate, and sends the total charging current I' at the first frequency. In some embodiments, the second frequency is greater than the first frequency, so that accurate monitoring can be achieved without causing a response burden on the charging device due to frequent sending of the total charging current I'.

[0102] In some embodiments, in order to prevent the total charging current from being too large and causing overcharging, a condition for stopping increasing the total charging current is set. Exemplarily, the main battery pack BMS calculates whether the maximum value of the absolute value of the current difference in the current difference set is less than or equal to the third current threshold at a third frequency. In response to the maximum value of the absolute value of the current difference in the current difference set being less than or equal to the third current threshold, the total charging current is stopped from being increased. The third current threshold is a positive number, which is the current threshold for stopping increasing the total charging current. The third current threshold is less than or equal to the first current threshold.

[0103] It can be understood that the maximum absolute value of the current difference in the current difference set represents the maximum degree of the actual charging current of the battery pack in the battery device from the allowed charging current. If the maximum absolute value is less than or equal to the third current threshold, it means that the actual charging current of each battery pack in the battery device is close to the allowed charging current, so the total charging current of multiple battery packs is stopped from increasing to prevent overcharging. That is, each battery pack has a higher charging efficiency and less risk of overcurrent protection.

[0104] In this embodiment, the maximum absolute value of the current difference indicates that the actual charging current of the corresponding battery pack has the largest difference with the allowable charging current, and the absolute value of the current difference of the battery pack is less than or equal to the third current threshold, indicating that the actual charging current of each battery pack is close to its own allowable charging current, thereby achieving a higher charging efficiency.

[0105] As can be seen from the above, in the process from the total charging current starting to increase to the total charging current stopping increasing, the total charging current increases at a first rate. In some embodiments, during the increase of the total charging current, the first rate is variable or constant. It is understandable that if the first rate is too large, overcharging and overcurrent protection are likely to occur in the later stage of the increase of the total charging current.

[0106] In some embodiments, in order to reduce the occurrence of overcurrent protection in the later stage of increase, in response to the increase of the total charging current, a request is made to reduce the first rate. That is, based on the total charging current increasing at the first rate, as the total charging current increases, a request is made to reduce the first rate so that the increment of the total charging current gradually slows down. In this way, the charging current of each battery pack increases smoothly, which is conducive to reducing overcharging and overcurrent protection, and improving charging efficiency and charging effect.

[0107] In some embodiments, the minimum value in the current difference is a positively correlated function with the first rate. In this embodiment, the minimum value in the current difference is a positive number, indicating that the actual charging current of the corresponding battery pack is closest to the allowed charging current, and the battery pack has a relatively large tendency to have overcurrent protection. Therefore, taking the battery pack with the greatest tendency to have overcurrent protection as a benchmark, it is determined that the first rate is a positively correlated function with its current difference. That is, the smaller the minimum value in the current difference, the closer the actual charging current of each battery pack is to the allowed charging current, and the smaller the first rate; the larger the minimum value in the current difference, the larger the actual charging current of each battery pack is from the allowed charging current, and the larger the first rate. In this way, the first rate is conducive to reducing overcharging and overcurrent protection, and improving charging efficiency and charging effect.

[0108] Exemplarily, the minimum value of the current difference and the first rate have the following positive correlation function;

[0109] V1=k×ΔI min ×N

[0110] Where V1 is the first rate, ΔI min is the minimum value of the current difference, N is the number of battery packs, and 0<k<1. For example, k is 0.5, that is, the product of half of the minimum value of the current difference and the number of battery packs is taken as the first rate.

[0111] In some embodiments, the current threshold and the quantity percentage threshold are set in stages to increase the total charging current in stages. For example, by setting a second current threshold less than the first current threshold, a second percentage looser than the first percentage, and a second rate less than the first rate, a slow rise stage for the total charging current is constructed. The second current threshold is a positive number, for example, the second current threshold is 0.3A or 0.5A, etc. The range of the second percentage is greater than or equal to 50% and less than or equal to 100%.

[0112] That is, in this embodiment, there are two rising stages, the first rising stage is a fast rising stage with the first current threshold, the first percentage and the first rate as parameters, and the second rising stage is a slow rising stage with the second current threshold, the second percentage and the second rate as parameters. The main battery pack BMS simultaneously monitors whether the trigger conditions of these two stages are met. If the trigger conditions of the fast rising stage are met, the program for increasing the total charging current at the first rate in the fast rising stage is started, and if the trigger conditions of the slow rising stage are met, the program for increasing the total charging current at the second rate in the slow rising stage is started. Among them, the trigger conditions of the fast rising stage: the second number of the calculated current difference is greater than or equal to the first current threshold, the first ratio of the second number to the first number, and the first ratio is greater than or equal to the first percentage; the trigger conditions of the slow rising stage: the third number of the calculated current difference is greater than or equal to the second current threshold, the second ratio of the third number to the first number, and the second ratio is greater than or equal to the second percentage.

[0113] like Fig. 9 As shown, the main battery pack BMS calculates a second quantity whose current difference is greater than or equal to the first current threshold, and a first ratio of the second quantity to the first quantity; at the same time, a third quantity whose current difference is greater than or equal to the second current threshold, and a second ratio of the third quantity to the first quantity are calculated. In response to the first ratio being greater than or equal to the first percentage, the main battery pack BMS requests to increase the total charging current at a first rate. In response to the second ratio being greater than or equal to the second percentage, the main battery pack BMS requests to increase the total charging current at a second rate.

[0114] It can be understood that compared with the fast rise stage, the second current threshold in the slow rise stage is less than the first current threshold, that is, when the trigger condition of the slow rise stage is met, the actual charging current of each battery pack is slightly different from the allowed charging current, so that a request is made to increase the total charging current at a lower second rate. Based on the smaller second rate, the risk of overcurrent is small, so the corresponding second percentage range is more relaxed. In some embodiments, 50% ≤ second percentage ≤ 100%. In some embodiments, 70% ≤ second percentage ≤ 100%. That is, when it is monitored that the number of battery packs with slightly lower charging efficiency reaches the range [70%, 100%], a request is made to increase the total charging current at the second rate, which is beneficial to reduce overcharging and overcurrent protection, so that multiple battery packs can be fully charged smoothly with higher charging efficiency.

[0115] In this embodiment, based on the fact that the second current threshold is less than the first current threshold and the second rate is less than the first rate, it can be seen that the stage of requesting to increase the total charging current at the second rate is the slow rise stage, and the stage of requesting to increase the total charging current at the first rate is the fast rise stage. In this way, the total charging current is requested to be increased in two stages, each stage corresponds to a different rate and current threshold, the overcurrent risk is small in the slow rise stage, and the corresponding second percentage range is more relaxed, so that the charging efficiency and overcurrent risk can be effectively balanced.

[0116] As can be seen from the above, in order to prevent the total charging current from being too large and causing overcharging, a condition for stopping increasing the total charging current is set. In the rapid rise stage, the main battery pack BMS calculates whether the maximum value of the absolute value of the current difference in the current difference set is less than or equal to the third current threshold at the third frequency. In response to the maximum value of the absolute value of the current difference in the current difference set being less than or equal to the third current threshold, the total charging current is stopped from being increased.

[0117] Similarly, in the slow rising stage, the main battery pack BMS calculates whether the maximum value of the absolute value of the current difference in the current difference set is less than or equal to the third current threshold at the third frequency. In response to the maximum value of the absolute value of the current difference in the current difference set being less than or equal to the third current threshold, the total charging current is stopped from being increased. The third current threshold is less than or equal to the second current threshold. In this way, on the basis of achieving a higher charging efficiency, overcharging is prevented by stopping the increase of the total charging current.

[0118] As can be seen from the above, the main battery pack BMS monitors the current difference set. In addition to monitoring the situation of low charging efficiency, it also monitors the situation of overcurrent protection tendency. That is, if a certain number of battery packs are detected to have the tendency of overcurrent protection, it will request to reduce the total charging current of multiple battery packs.

[0119] In some embodiments, a current threshold and a quantity percentage threshold are set to determine whether a certain quantity percentage of battery packs have a tendency to cause overcurrent protection, thereby triggering a request to reduce the total charging current.

[0120] like Fig.10 As shown, the main battery pack BMS calculates a fourth number whose current difference is less than or equal to a fourth current threshold, and a third ratio of the fourth number to the first number. In response to the third ratio being greater than or equal to a third percentage, the main battery pack BMS requests to reduce the total charging current of the plurality of battery packs at a third rate.

[0121] Among them, the fourth current threshold is a current threshold for monitoring the tendency of overcurrent protection, and the fourth current threshold is a negative number. In some embodiments, the fourth current threshold is -0.5A or -1A, etc. It can be understood that those skilled in the art can set the fourth current threshold according to the actual situation of the battery equipment. If the current difference is less than or equal to the fourth current threshold, it means that the corresponding battery pack is charging with a larger current that is higher than its own allowable charging current, and has a tendency to cause overcurrent protection. If the battery pack has an overcurrent protection, charging will stop, and it will not be able to be fully charged in the current overcharge, affecting the overall charging effect and charging efficiency of the battery equipment.

[0122] The third percentage is the threshold for monitoring the proportion of battery packs with a tendency to cause overcurrent protection. If the third ratio is greater than or equal to the third percentage, it means that the number of battery packs with a tendency to cause overcurrent protection has reached a certain proportion, and more battery packs have the risk of causing overcurrent protection. Therefore, it is requested to reduce the total charging current at the third rate so that the charging current of each battery pack decreases smoothly, which is conducive to balancing the charging efficiency and reducing overcurrent protection.

[0123] It is understandable that if the third percentage is too large, that is, it is detected that an excessive number of battery packs have the risk of overcurrent protection, and the total charging current is reduced, which may easily cause the charging current of a certain battery pack to be greater than the overcurrent protection threshold, resulting in overcurrent protection. In some embodiments, 0 < the third percentage ≤ 20%, that is, it is detected that the battery packs with a proportion in the range of (0, 20%] have a tendency to have overcurrent protection, and a request to reduce the total charging current is helpful to reduce the problem of charging efficiency and charging effect affected by overcurrent protection. In some embodiments, 0 < the third percentage ≤ 10%. That is, it is detected that the battery packs with a proportion in the range of (0, 10%] have a tendency to have overcurrent protection, and a request to reduce the total charging current at a third rate is helpful to reduce the problem of charging efficiency affected by overcurrent protection.

[0124] Among them, the third rate is the rate of reduction of the total charging current, that is, the total charging current is reduced at the third rate. When the third ratio is monitored to be greater than or equal to the third percentage, the total charging current is reduced at the third rate. Compared with requesting the total charging current to jump directly to a small current value, requesting to reduce the total charging current at the third rate reduces the risk of overcurrent and ensures charging efficiency. Based on the main battery pack BMS, the total charging current is sent to the charging device at a certain frequency, so that when the total charging current is reduced to the current sending time at the third rate, the reduced total charging current is sent to the charging device at the current sending time.

[0125] For example, when the main battery pack detects that the third ratio is greater than or equal to the third percentage at time t2, the current total charging current I is obtained, and a request is made to reduce the total charging current of the multiple battery packs at a third rate. That is, the total charging current can be expressed by the following formula:

[0126] I '' =I-V3*Δt

[0127] Wherein, I is the current total charging current before the third rate is reduced, V3 is the third rate, Δt is the time for reducing the total charging current, and I″ is the total charging current after the third rate is reduced. In some embodiments, Δt=t-t2, t is the current moment, and t2 is the moment when the number of battery packs with a tendency to overcurrent protection is monitored to reach a third percentage.

[0128] It can be understood that the main battery pack BMS sends the total charging current I″ at a first frequency, calculates whether the third ratio is greater than or equal to the third percentage at a second frequency, and if so, still reduces the total charging current at the third rate and sends the total charging current I″ at the first frequency. In some embodiments, the second frequency is greater than the first frequency, so that accurate monitoring can be achieved without causing a response burden on the charging device due to frequent sending of the total charging current I″.

[0129] In some embodiments, in order to prevent the total charging current from being too small and causing low charging efficiency, a condition for stopping reducing the total charging current is set. Exemplarily, the main battery pack calculates whether the maximum value of the absolute value of the current difference in the current difference set is less than or equal to the sixth current threshold at a third frequency. In response to the maximum value of the absolute value of the current difference in the current difference set being less than or equal to the sixth current threshold, the total charging current of the multiple battery packs is stopped from being reduced. The sixth current threshold is a positive number, which is the current threshold for stopping reducing the total charging current. The sixth current threshold is less than or equal to the absolute value of the fourth current threshold.

[0130] It can be understood that the maximum value of the absolute value of the current difference in the current difference set represents the maximum degree of distance between the actual charging current of the battery pack in the battery device and the allowed charging current. If the maximum value of the absolute value is less than or equal to the sixth current threshold, it means that the actual charging current of each battery pack in the battery device is close to the allowed charging current, and thus, the total charging current of the multiple battery packs is stopped from being reduced to prevent the charging efficiency from becoming low. In this way, while reducing the risk of overcurrent protection by reducing the total charging current, each battery pack has a higher charging efficiency.

[0131] In this embodiment, the maximum absolute value of the current difference indicates that the actual charging current of the corresponding battery pack has the largest difference with the allowable charging current, and the absolute value of the current difference of the battery pack is less than or equal to the sixth current threshold, indicating that the actual charging current of each battery pack is close to its own allowable charging current, thereby achieving a higher charging efficiency.

[0132] As can be seen from the above, in the process from when the total charging current starts to decrease to when it stops decreasing, the total charging current decreases at the third rate. In some embodiments, during the period of decreasing the total charging current, the third rate is variable or constant. It is understandable that if the third rate is too large, the phenomenon of low charging efficiency is likely to occur in the later stage of increasing the total charging current.

[0133] In some embodiments, in order to prevent the problem of low charging efficiency in the later stage of the reduction, in response to the reduction of the total charging current, a request is made to reduce the third rate. That is, based on the total charging current being reduced at the third rate, as the total charging current is reduced, a request is made to reduce the third rate so that the reduction amount of the total charging current is gradually slowed down. In this way, the charging current of each battery pack is reduced smoothly, which is conducive to maintaining a high charging efficiency while reducing the risk of overcurrent.

[0134] In some embodiments, the minimum value in the current difference is negatively correlated with the third rate. In this embodiment, the minimum value in the current difference is a negative number, indicating that the actual charging current of the corresponding battery pack exceeds the allowable charging current to the greatest extent, and the battery pack has a relatively large tendency to have overcurrent protection. Therefore, taking the battery pack with the greatest tendency to have overcurrent protection as a benchmark, it is determined that the third rate is negatively correlated with its current difference, that is, the smaller the minimum value in the current difference, the greater the degree of exceeding the allowable charging current, and the greater the third rate, so that the third rate quickly reduces the charging current, which is conducive to reducing overcurrent protection and maintaining a high charging efficiency.

[0135] Exemplarily, the minimum value of the current difference and the third rate are negatively correlated with each other as follows:

[0136] V3=-ΔI min ×N

[0137] Where V3 is the third rate, ΔI min is the minimum value of the current difference, and N is the number of battery packs.

[0138] In this embodiment, the third rate is determined as the product of the inverse of the minimum value of the current differences and the number of battery packs.

[0139] In some embodiments, the current threshold and the quantity percentage threshold are set in stages to reduce the total charging current in stages. For example, by setting a fifth current threshold greater than the fourth current threshold, a fourth percentage that is looser than the third percentage, and a fourth rate that is less than the third rate, a slow decrease stage for the total charging current is constructed. The fifth current threshold is a negative number, for example, the fifth current threshold is -0.2A or -0.5A, etc. The range of the fourth percentage is greater than 0 and less than or equal to 30%.

[0140] That is, in this embodiment, there are two descending stages, the first descending stage is a fast descending stage with the fourth current threshold, the third percentage and the third rate as parameters, and the second descending stage is a slow descending stage with the fifth current threshold, the fourth percentage and the fourth rate as parameters. The main battery pack BMS simultaneously monitors whether the trigger conditions of these two stages are met. If the trigger conditions of the fast descending stage are met, the program of reducing the total charging current at the third rate in the fast descending stage is started, and if the trigger conditions of the slow descending stage are met, the program of reducing the total charging current at the fourth rate in the slow descending stage is started. Among them, the triggering conditions of the fast descending stage: the fourth number of the calculated current difference is less than or equal to the fourth current threshold, the third ratio of the fourth number to the first number, and the third ratio is greater than or equal to the third percentage; the triggering conditions of the slow descending stage: the fifth number of the calculated current difference is less than or equal to the fifth current threshold, the fourth ratio of the fifth number to the first number, and the fourth ratio is greater than or equal to the fourth percentage.

[0141] like Fig.11 As shown, the main battery pack BMS calculates a fourth quantity whose current difference is less than or equal to a fourth current threshold, and a third ratio of the fourth quantity to the first quantity; at the same time, it calculates a fifth quantity whose current difference is less than or equal to a fifth current threshold, and a fourth ratio of the fifth quantity to the first quantity. In response to the third ratio being greater than or equal to the third percentage, the main battery pack BMS requests to reduce the total charging current at a third rate. In response to the fourth ratio being greater than or equal to the fourth percentage, the main battery pack BMS requests to reduce the total charging current at a fourth rate.

[0142] It can be understood that compared with the fast descent stage, the fifth current threshold (negative number) in the slow descent stage is greater than the fourth current threshold (negative number), that is, when the triggering conditions of the slow descent stage are met, the actual charging current of each battery pack is slightly different from the allowed charging current, so it is requested to reduce the total charging current at a lower fourth rate. Based on the smaller fourth rate, not only the overcurrent risk is alleviated, but also a higher charging efficiency is guaranteed, so that the corresponding fourth percentage range is more relaxed. In some embodiments, 0 < fourth percentage ≤ 30%. In some embodiments, 0 < fourth percentage ≤ 15%. That is, when it is monitored that the number of battery packs with a slightly lower tendency to overcurrent protection reaches the range (0, 15%], it is requested to reduce the total charging current at the fourth rate, which is beneficial to balance the charging efficiency and reduce overcurrent protection.

[0143] In this embodiment, based on the fact that the fifth current threshold is greater than the fourth current threshold and the fourth rate is less than the third rate, it can be seen that the stage of requesting to reduce the total charging current at the fourth rate is the slow decline stage, and the stage of requesting to reduce the total charging current at the third rate is the fast decline stage. In this way, the total charging current is requested to be reduced in two stages, each stage corresponds to a different rate and current threshold, the overcurrent risk is small in the slow decline stage, and the corresponding fourth percentage range is more relaxed, so that the charging efficiency and overcurrent risk can be effectively balanced.

[0144] As can be seen from the above, in order to prevent the total charging current from being too small and causing low charging efficiency, a condition for stopping reducing the total charging current is set. In the rapid decline stage, the main battery pack BMS calculates whether the maximum value of the absolute value of the current difference in the current difference set is less than or equal to the sixth current threshold at the third frequency. In response to the maximum value of the absolute value of the current difference in the current difference set being less than or equal to the sixth current threshold, the total charging current is stopped from being reduced. Among them, the sixth current threshold is less than or equal to the absolute value of the fourth current threshold.

[0145] Similarly, in the slow descent stage, the main battery pack BMS calculates whether the maximum value of the absolute value of the current difference in the current difference set is less than or equal to the sixth current threshold at the third frequency. In response to the maximum value of the absolute value of the current difference in the current difference set being less than or equal to the sixth current threshold, the total charging current is stopped from being reduced. Among them, the sixth current threshold is less than or equal to the absolute value of the fifth current threshold. In this way, on the basis of reducing the risk of overcurrent protection, the total charging current is stopped from being reduced to prevent the phenomenon of low charging efficiency.

[0146] See also Fig.12 , Fig.12 This is a flow chart of a method for parallel charging of multiple battery packs in some embodiments of the present application. The main battery pack BMS performs the following steps:

[0147] S10, the battery device starts charging and requests a total charging current of an initial value linit.

[0148] S20, obtaining a current difference value set, where the current difference value set includes a current difference between an allowed charging current and an actual charging current of each battery pack.

[0149] After S20, four branches are executed in parallel, and the four branches include: S30 fast rising stage, S40 slow rising stage, S50 fast falling stage and S60 slow falling stage.

[0150] Wherein, S30 includes: S31, calculating a second number whose current difference is greater than or equal to a first current threshold, and a first ratio of the second number to the first number; S32, in response to the first ratio being greater than or equal to a first percentage, requesting to increase the total charging current of the plurality of battery packs at a first rate V1. Wherein, the first current threshold is a positive number, 75%≤first percentage≤100%.

[0151] S40 includes: S41, calculating a third number whose current difference is greater than or equal to a second current threshold, and a second ratio of the third number to the first number; S42, in response to the second ratio being greater than or equal to a second percentage, requesting to increase the total charging current of the plurality of battery packs at a second rate V2. The second current threshold is a positive number, the second current threshold is less than the first current threshold, the second rate V2 is less than the first rate V1, and 50%≤second percentage≤100%.

[0152] S50 includes: S51, calculating a fourth number whose current difference is less than or equal to a fourth current threshold, and a third ratio of the fourth number to the first number; S52, in response to the third ratio being greater than or equal to a third percentage, requesting to reduce the total charging current of the plurality of battery packs at a third rate V3. The fourth current threshold is a negative number, 0<third percentage≤20%.

[0153] S60 includes: S61, calculating a fifth number whose current difference is less than or equal to a fifth current threshold, and a fourth ratio of the fifth number to the first number; S62, in response to the fourth ratio being greater than or equal to a fourth percentage, requesting to reduce the total charging current of the plurality of battery packs at a fourth rate V4. The fifth current threshold is a negative number, the fifth current threshold is greater than the fourth current threshold, the fourth rate V4 is less than the third rate V3, and 0<fourth percentage≤30%.

[0154] For branches S30 and S40, in step S71, when the maximum absolute value of the current difference in the current difference set is less than or equal to the third current threshold, execute: S72, stop increasing the total charging current of the multiple battery packs. The third current threshold is a positive number, the third current threshold is less than or equal to the first current threshold, and the third current threshold is less than or equal to the second current threshold.

[0155] For branches S50 and S60, in judgment step S81, when the maximum absolute value of the current difference in the current difference set is less than or equal to the sixth current threshold, execute: S82, stop reducing the total charging current of the multiple battery packs. Wherein, the sixth current threshold is a positive number, the sixth current threshold is less than or equal to the absolute value of the fourth current threshold, or the sixth current threshold is less than or equal to the absolute value of the fifth current threshold.

[0156] That is, in this embodiment, the main battery pack BMS monitors in real time whether the trigger conditions of the four stages of S30 fast rising stage, S40 slow rising stage, S50 fast falling stage and S60 slow falling stage are met. If any of them is met, the total charging current is adjusted according to the adjustment strategy of the corresponding stage. In this way, the total charging current is dynamically adjusted, so that the charging efficiency and charging effect of the battery equipment can be improved.

[0157] Electrical devices

[0158] Some embodiments of the present application also provide an electrical device, including the battery device in any one of the above embodiments.

[0159] The electrical device of the present application is not particularly limited. In some embodiments, the electrical device may include a battery energy storage system, an electric motorcycle, an electric bicycle, an electric tool, a sweeping robot, an automatic guided vehicle (AGV), an uninterruptible power supply (UPS), etc.

[0160] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, 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 invention.

Claims

1. A method for parallel charging of multiple battery packs, characterized in that: include: Obtaining a current difference between an allowed charging current and an actual charging current of each battery pack to obtain a current difference value set, and defining the number of current difference values ​​in the current difference value set as a first number; Calculating a second number of current differences greater than or equal to a first current threshold, and a first ratio of the second number to the first number; In response to the first ratio being greater than or equal to a first percentage, requesting to increase a total charging current of the plurality of battery packs at a first rate; The first current threshold is a positive number, the total charging current is used to charge the multiple battery packs, and 75%≤the first percentage≤100%.

2. The method according to claim 1, characterized in that In response to the total charging current increasing, a decrease in the first rate is requested.

3. The method according to claim 1 or 2, characterized in that: There is a positive correlation function between the minimum value of the current difference and the first rate.

4. The method according to claim 1, characterized in that: 85%≤the first percentage≤100%.

5. The method according to any one of claims 1 to 4, characterized in that: The method comprises: Calculating a third number of current differences greater than or equal to a second current threshold, and a second ratio of the third number to the first number; In response to the second ratio being greater than or equal to a second percentage, requesting to increase the total charging current of the plurality of battery packs at a second rate; The second current threshold is a positive number, the second current threshold is less than the first current threshold, the second rate is less than the first rate, and 50%≤the second percentage≤100%.

6. The method according to claim 5, characterized in that 70%≤the second percentage≤100%.

7. The method according to claim 1 or 5, characterized in that: The method comprises: In response to a maximum value of absolute values ​​of current differences in the current difference value set being less than or equal to a third current threshold, stopping increasing a total charging current of the plurality of battery packs; The third current threshold is a positive number, the third current threshold is less than or equal to the first current threshold, or the third current threshold is less than or equal to the second current threshold.

8. The method according to claim 1, characterized in that The method comprises: calculating a fourth number of current differences less than or equal to a fourth current threshold, and a third ratio of the fourth number to the first number; In response to the third ratio being greater than or equal to a third percentage, requesting to reduce the total charging current of the plurality of battery packs at a third rate; The fourth current threshold is a negative number, and 0<the third percentage≤20%.

9. The method according to claim 8, characterized in that In response to the total charging current decreasing, a decrease in the third rate is requested.

10. The method according to claim 9, characterized in that The minimum value of the current differences is negatively correlated with the third rate.

11. The method according to claim 8, characterized in that 0<the third percentage≤10%.

12. The method according to any one of claims 8 to 11, characterized in that: The method comprises: calculating a fifth number of which the current difference is less than or equal to a fifth current threshold, and a fourth ratio of the fifth number to the first number; In response to the fourth ratio being greater than or equal to the fourth percentage, requesting to reduce the total charging current of the plurality of battery packs at a fourth rate; The fifth current threshold is a negative number, the fifth current threshold is greater than the fourth current threshold, the fourth rate is less than the third rate, and 0<the fourth percentage≤30%.

13. The method according to claim 12, characterized in that 0<the fourth percentage≤15%.

14. The method according to claim 8 or 12, characterized in that: The method comprises: In response to a maximum value of absolute values ​​of current differences in the current difference value set being less than or equal to a sixth current threshold, stopping reducing a total charging current of the plurality of battery packs; The sixth current threshold is a positive number, the sixth current threshold is less than or equal to the absolute value of the fourth current threshold, or the sixth current threshold is less than or equal to the absolute value of the fifth current threshold.

15. A battery management system, characterized in that: The invention comprises a processor and a memory, wherein the memory is used to store instructions, and the processor is used to execute the instructions to implement the method for parallel charging of multiple battery packs according to any one of claims 1 to 14.

16. A battery device, characterized in that: The invention comprises a plurality of battery packs and a battery management system as claimed in claim 15 .

17. An electrical device, characterized in that: Comprising a battery device as claimed in claim 16.

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