Battery charging control method and battery management system

Abstract

The invention discloses a battery charging control method and a battery management system, which are used for improving the precision of controlling battery charging. The method comprises the following steps: determining a cycle life consumption value of each charging process based on an initial state of charge (SOC) and a cut-off SOC of a battery in each charging process; adding the cycle life consumption value in each charging process; and if the sum of the cycle life consumption values of each charging process is greater than the designed cycle life, controlling the charging rate of the battery to be lower than a rate threshold. According to the method, the actual influence of the SOC of the battery on the cycle life of the battery is considered, and the cycle life consumption judged according to the initial SOC and the cut-off SOC is closer to the actual level, so that the charging rate of the battery can be more accurately controlled.

Description

Technical Field

[0001] The present application relates to the field of battery management technology, and in particular to a battery charging control method and a battery management system. Background Art

[0002] A battery's full charge and discharge is considered a cycle. The battery's cycle life refers to the number of cycles the battery can withstand before its capacity drops to a certain threshold.

[0003] Because excessively high charge rates can damage the battery's cycle life, current charging control strategies consider the battery's cycle life and maintain the battery's fast charge rate at a low level, resulting in a waste of battery performance. However, if the charge rate is not limited, high-rate currents can seriously damage the battery.

[0004] Therefore, how to comprehensively consider the cycle life of the battery and timely limit the charging rate is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In view of the above problems, the present application provides a battery charging control method and a battery management system to improve the accuracy of controlling battery charging.

[0006] In a first aspect, the present application provides a battery charging control method, comprising: determining a cycle life consumption value for each charging process based on the starting state of charge (SOC) and the ending SOC of the battery during each charging process; adding the cycle life consumption values ​​for each charging process; and if the sum of the cycle life consumption values ​​of each charging process is greater than the designed cycle life, controlling the charging rate of the battery to be lower than a rate threshold.

[0007] The current cycle life test method tests the number of full charge and discharge cycles a battery undergoes, for example, the number of cycles from SOC 0% to 100% and then back to 0%. However, in actual use, users often do not strictly charge from 0% to 100%, but instead charge multiple times until the SOC changes cumulatively by 100%. Furthermore, the effect of the charge rate on the battery's cycle life varies with different SOCs. Therefore, a cumulative SOC change of 100% during multiple charging processes theoretically consumes one cycle, but in reality, the number of cycles consumed may not be equal to 1 due to the influence of SOC.

[0008] This embodiment takes into account the actual impact of the battery's SOC on the battery's cycle life, and the cycle life consumption determined based on the SOC is close to the actual level. Furthermore, the battery's charge rate can be accurately controlled.

[0009] In some embodiments, since a higher SOC indicates a lower potential at the battery's negative electrode, and some side reactions generated by the battery are related to the potentials of the positive and negative electrodes, the greater the voltage differential between the positive and negative electrodes, the more intense the reaction. Therefore, determining the cycle life consumption value for each charging process based on the starting SOC and ending SOC of the battery during each charging process includes: if the difference between the ending SOC and the starting SOC is the same, the greater the starting SOC, the greater the determined cycle life consumption value.

[0010] In some embodiments, since a higher SOC results in a lower potential at the battery's negative electrode, and some side reactions generated by the battery are related to the potentials of the positive and negative electrodes, the greater the voltage differential between the positive and negative electrodes, the more intense the reaction. Therefore, based on the starting SOC and ending SOC of each battery charging process, determining the cycle life consumption value for each charging process includes: if the ending SOC is less than or equal to the minimum value of the SOC range, the determined cycle life consumption value is less than the SOC difference; if the starting SOC and the ending SOC are within the SOC range, the determined cycle life consumption value is equal to the SOC difference; if the starting SOC is greater than or equal to the maximum value of the SOC range, the determined cycle life consumption value is greater than the SOC difference; wherein the SOC difference is the difference between the ending SOC and the starting SOC.

[0011] In the second aspect, the present application provides a battery management system, including a data analysis device, a counter and a controller: the data analysis device is used to determine the cycle life consumption value of each charging process based on the starting SOC and the ending SOC of the battery in each charging process; the counter is used to add the cycle life consumption value of each charging process; the controller is used to control the charging rate of the battery to be lower than the rate threshold if the sum of the cycle life consumption values ​​of each charging process is greater than the designed cycle life.

[0012] In some embodiments, the data analysis device is configured to: when the difference between the cut-off SOC and the starting SOC is the same, the greater the starting SOC, the greater the determined cycle life consumption value.

[0013] In some embodiments, the data analysis device is used to: if the cut-off SOC is less than or equal to the minimum value of the SOC interval, the determined cycle life consumption value is less than the SOC difference value; if the starting SOC and the cut-off SOC are within the SOC interval, the determined cycle life consumption value is equal to the SOC difference value; if the starting SOC is greater than or equal to the maximum value of the SOC interval, the determined cycle life consumption value is greater than the SOC difference value; wherein the SOC difference value is the difference between the cut-off SOC and the starting SOC.

[0014] 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

[0015] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0016] Figure 1 This is a flowchart of a battery charging method according to some embodiments of the present application;

[0017] Figure 2 This is a schematic diagram of the corresponding relationship between the starting SOC and the cycle life consumption value in some embodiments of the present application;

[0018] Figure 3 This is a schematic diagram of the structure of a battery management system according to some embodiments of the present application;

[0019] Figure 4 This is a schematic diagram of the structure of a computer device according to some embodiments of the present application. DETAILED DESCRIPTION

[0020] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0022] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0023] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0025] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0026] To facilitate understanding of the solutions in this application, the following technical terms and background technologies used are explained:

[0027] 1. Cycle life

[0028] Cycle life, also known as cycle count, is a battery's full charge and discharge cycle. A cycle is defined as the battery's SOC increasing from 0% to 100% and then decreasing from 100% to 0%. A battery's cycle life refers to the number of cycles it can withstand before its capacity drops below a certain threshold. For lithium iron phosphate batteries, for example, this number is over 2,000 cycles.

[0029] 2. Charging rate

[0030] The charge rate primarily describes the relationship between charging speed and battery capacity. For example, a charge rate that fully charges a battery in one hour is called 1C, while a charge rate that fully charges a battery in 0.5 hours is called 2C. It's generally accepted that a battery's charge rate exceeding 1C is considered fast charging, while a charge rate below 1C is considered slow charging.

[0031] 3. State of Charge

[0032] The state of charge (SOC) refers to the ratio of the remaining capacity of a battery to the capacity of the battery when fully charged. It is used to indicate the available state of the remaining charge in the battery.

[0033] Under the current charging control strategy, once the number of charge and discharge cycles of the battery exceeds the pre-measured cycle life, the battery charging rate will be limited.

[0034] For example, if the charge rate is greater than 1C, the battery's cycle life is 2000 cycles. The user starts charging when the battery's SOC reaches 60% and stops charging when the SOC reaches 100%. The user then uses electricity, discharging the battery to 40%. The user starts charging at 40% and stops charging at 100%. The cumulative SOC change of 100% during these two charging processes consumes one cycle. After 2000 such repeated uses, the battery's charge rate is limited to less than 1C.

[0035] However, after repeated experiments and research, technicians found that in actual applications, it often happens that the battery performance is limited to the charging rate while it can still support fast charging capabilities, or it often happens that the battery is not limited in time to the charging rate, and the high-rate current seriously damages the battery.

[0036] Therefore, how to limit the charging rate in a timely manner is a technical problem that needs to be solved urgently.

[0037] Based on the above technical problems, the present application provides a battery charging control method for improving the accuracy of controlling battery charging.

[0038] like Figure 1 As shown, the method includes:

[0039] Step 101 : determining a cycle life consumption value of each charging process based on a starting SOC and a ending SOC of the battery in each charging process.

[0040] It should be understood that each charging process here refers to the continuous charging of the battery over a period of time. For example, the battery is continuously charged from t0 to t1, continuously discharged from t1 to t2, and continuously charged again from t2 to t3. In this case, the battery undergoes two charging processes from t0 to t1 and t2 to t3. In addition, the starting SOC refers to the battery's SOC at the beginning of the charging process, and the ending SOC refers to the battery's SOC at the end of the charging process.

[0041] It should be noted that the cycle life consumption value represents the amount of battery cycle life consumed during a single charging process. For example, if a battery's designed cycle life is 2000 cycles, and a single charge process starts at 40% SOC and ends at 100% SOC, the corresponding cycle life consumption value is 0.6 cycles. After this charging process, the battery's cycle life is 1999.4 cycles.

[0042] Step 102: summing up the cycle life consumption value during each charging process.

[0043] Step 103: If the sum of the cycle life consumption values ​​of each charging process is greater than the designed cycle life, the charging rate of the battery is controlled to be lower than the rate threshold.

[0044] It should be noted that the design cycle life here refers to the number of cycles that the battery can withstand before the battery capacity drops to a certain threshold.

[0045] Because the higher the SOC, the lower the potential of the battery's negative electrode, and some side reactions produced by the battery are related to the potential of the positive and negative electrodes of the battery, the greater the voltage difference between the positive and negative electrodes, the more intense the side reactions. For example, the higher the SOC of a lithium-ion battery during charging, the lower the potential of the negative electrode. During the charging process, lithium ions migrate to the negative electrode, but the excessively low potential weakens the negative electrode's ability to quickly accept lithium ions. Under such operating conditions, the probability of lithium dendrites forming inside the battery increases. In addition, excessively high charging current generates a large amount of Joule heat. Combined with the large voltage difference between the positive and negative electrodes, the chemical reactions inside the battery will accelerate, and the evaporation of the electrolyte will produce a large amount of gas, posing a risk of battery explosion.

[0046] Therefore, the impact of the charging process on the cycle life varies depending on the battery's SOC. The present embodiment takes into account the actual impact of the battery's SOC on the battery's cycle life, and the cycle life consumption determined based on the SOC is close to the actual level. Furthermore, the battery's charge rate can be accurately and timely controlled.

[0047] There are multiple methods for determining the cycle life consumption value in the above battery charging control method, which are described below with reference to embodiments:

[0048] In some embodiments, determining the cycle life consumption value of each charging process based on the starting state of charge (SOC) and the ending state of charge (SOC) of the battery during each charging process includes:

[0049] When the difference between the end SOC and the start SOC is the same, the greater the start SOC, the greater the determined cycle life consumption value.

[0050] For example, during the first charging process, the battery starts at 60% SOC and ends at 100%. During the second charging process, the battery starts at 40% SOC and ends at 80%. According to the traditional method of measuring cycle life loss, the difference in SOC between the two charging processes is 80%, which theoretically consumes 0.8 cycles of life. However, in the solution of this embodiment, the difference between the end SOC and the starting SOC is 40%. The relationship between the starting SOC and the cycle life consumption value is as follows: Figure 2 As shown in the figure, the cycle life consumption value corresponding to the starting SOC of 60% is 0.5 times, and the cycle life consumption value corresponding to the starting SOC of 40% is 0.35 times. Therefore, although the cumulative SOC change of 80% during the two charging processes is actually 0.88 times.

[0051] Those skilled in the art should know that in addition to the form shown in the accompanying drawings, the corresponding relationship between the starting SOC and the cycle life consumption value can also be designed according to the actual parameters of the battery and the charging and discharging environmental conditions, and this application does not limit this.

[0052] In some embodiments, determining the cycle life consumption value of each charging process based on the starting state of charge (SOC) and the ending state of charge (SOC) of the battery during each charging process includes:

[0053] If the cutoff SOC is less than or equal to the minimum value of the SOC interval, the determined cycle life consumption value is less than the SOC difference value;

[0054] If the starting SOC and the ending SOC are within the SOC range, the determined cycle life consumption value is equal to the SOC difference;

[0055] If the starting SOC is greater than or equal to the maximum value of the SOC interval, the determined cycle life consumption value is greater than the SOC difference value.

[0056] It should be noted that the SOC difference is the difference between the cut-off SOC and the starting SOC.

[0057] In Example 1, the SOC range is [40%, 60%]. During the first charge, the battery's starting SOC is 0% and its ending SOC is 30%, with an SOC difference of 0.3, corresponding to a cycle life consumption of 0.28 cycles. During the second charge, the starting SOC is 40% and the ending SOC is 50%, with an SOC difference of 0.1, corresponding to a cycle life consumption of 0.1 cycles. During the third charge, the starting SOC is 70% and the ending SOC is 100%, with an SOC difference of 0.3, corresponding to a cycle life consumption of 0.8 cycles. Therefore, the cumulative SOC change over the three charge processes is 0.7. According to the existing charging control strategy, 0.7 cycles of life should be consumed, but in fact, 1.18 cycles of life are consumed.

[0058] In Example 2, the SOC interval is [40%, 60%]. During the three charging cycles, the battery starts at 0% SOC and ends at 30%. The SOC difference between each cycle is 0.3, and the corresponding cycle life consumption for each charging process is 0.28 cycles. Therefore, the cumulative SOC change over the three charging processes is 0.9. According to the existing charging control strategy, 0.9 cycles of cycle life should be consumed, but the actual cycle life consumed is 0.84 cycles.

[0059] In Example 3, the SOC interval is [40%, 60%]. During the three charging cycles, the battery starts at 60% and ends at 90%. The SOC difference between each charge is 0.3, and the corresponding cycle life consumption for each charge process is 0.9. Therefore, the cumulative SOC change over the three charging processes is 0.9. According to the existing charging control strategy, 0.9 cycles of life should be consumed, but the actual cycle life consumed is 2.7 cycles.

[0060] Based on the same technical concept, the present application provides a battery management system. The embodiments of the system can refer to the embodiments of the battery charging control method, and the repeated parts will not be repeated.

[0061] This application provides a battery management system such as Figure 3 As shown, the battery management system 30 includes a data analysis device 301, a counter 302 and a controller 303:

[0062] The data analysis device 301 is used to determine the cycle life consumption value of each charging process based on the starting SOC and the ending SOC of the battery in each charging process;

[0063] Counter 302, used to sum the cycle life consumption value during each charging process;

[0064] Controller 303 is configured to control the battery's charge rate to be below a rate threshold if the sum of the cycle life consumption values ​​from each charging process is greater than the designed cycle life. Exemplarily, data analysis device 301 communicates with the battery's data acquisition module, such as a battery management unit on the battery, to obtain the battery's open circuit voltage and cutoff voltage. Data analysis device 301 calculates the starting SOC and the ending SOC based on the battery's open circuit voltage, the cutoff voltage, and the battery's capacity. Furthermore, data analysis device 301 determines the cycle life consumption value based on the starting SOC and the ending SOC.

[0065] In some embodiments, because a higher SOC indicates a lower potential at the battery's negative electrode, and some side reactions generated by the battery are related to the potentials of the positive and negative electrodes, the greater the voltage difference between the positive and negative electrodes, the more intense the reaction. Therefore, the data analysis device 301 is configured to: when the difference between the cut-off SOC and the starting SOC is the same, the greater the starting SOC, the greater the cycle life consumption value determined.

[0066] In some embodiments, since the higher the SOC, the lower the potential of the battery's negative electrode, and some side reactions generated by the battery are related to the potential of the battery's positive and negative electrodes, the greater the voltage difference between the positive and negative electrodes, the more intense the reaction. Therefore, the data analysis device 301 is used to:

[0067] If the cutoff SOC is less than or equal to the minimum value of the SOC interval, the determined cycle life consumption value is less than the SOC difference value;

[0068] If the starting SOC and the ending SOC are within the SOC range, the determined cycle life consumption value is equal to the SOC difference;

[0069] If the starting SOC is greater than or equal to the maximum value of the SOC interval, the determined cycle life consumption value is greater than the SOC difference value.

[0070] It should be noted that the SOC difference is the difference between the cut-off SOC and the starting SOC.

[0071] Corresponding to the battery charging control method provided above, the embodiment of the present application also provides a computer device. Figure 4 The computer device 40 in the embodiment of the present application includes: a memory 401, one or more processors 402 ( Figure 4 Only one is shown) and a computer program stored in memory 401 and executable on the processor. Memory 401 is used to store software programs and units, and processor 402 executes the software programs and units stored in memory 401 to execute various functional applications and process data to obtain resources corresponding to the above-mentioned preset events.

[0072] In the case where the computer device is a server, the processor 402 can implement the steps of the above-mentioned battery charging control method by running the above-mentioned computer program stored in the memory 401, which will not be repeated here.

[0073] In the case where the computer device is a client, the processor 402 can implement the steps of the above-mentioned battery charging control method by running the above-mentioned computer program stored in the memory 401, which will not be repeated here.

[0074] It should be understood that in the embodiment of the present application, the processor 402 may be a central processing unit (CPU), and may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0075] The memory 401 may include a read-only memory and a random access memory, and provides instructions and data to the processor 402. A portion or all of the memory 401 may also include a non-volatile random access memory. For example, the memory 401 may also store device category information.

[0076] Those skilled in the art will appreciate that the algorithmic steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of external device software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0077] In the embodiments provided in this application, it should be understood that the disclosed systems and methods can be implemented in other ways. If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the associated hardware through a computer program. The above-mentioned computer program can be stored in a computer-readable storage medium, and the computer program, when executed by a processor, can implement the steps of the above-mentioned various method embodiments. Wherein, the above-mentioned computer program includes computer program code, and the above-mentioned computer program code can be in source code form, object code form, executable file or some intermediate form, etc. The above-mentioned computer-readable storage medium may include: any entity or device capable of carrying the above-mentioned computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer-readable memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the above-mentioned computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practices in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practices, computer-readable storage media does not include electrical carrier signals and telecommunication signals.

[0078] 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. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. 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, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery charging control method, characterized in that: include: Determining a cycle life consumption value of each charging process based on a starting state of charge (SOC) and a cutoff state of charge (SOC) of the battery during each charging process; Adding the cycle life consumption value during each charging process; If the sum of the cycle life consumption values ​​of each charging process is greater than the designed cycle life, the charging rate of the battery is controlled to be lower than a rate threshold.

2. The battery charging control method according to claim 1, wherein: Determining the cycle life consumption value of each charging process based on the starting state of charge SOC and the ending state of charge SOC of the battery during each charging process includes: When the difference between the cut-off SOC and the starting SOC is the same, the greater the starting SOC is, the greater the determined cycle life consumption value is.

3. The battery charging control method according to claim 1, wherein: Determining the cycle life consumption value of each charging process based on the starting state of charge SOC and the ending state of charge SOC of the battery during each charging process includes: If the cut-off SOC is less than or equal to the minimum value of the SOC interval, the determined cycle life consumption value is less than the SOC difference value; If the starting SOC and the ending SOC are within the SOC range, the determined cycle life consumption value is equal to the SOC difference; If the starting SOC is greater than or equal to the maximum value of the SOC range, the determined cycle life consumption value is greater than the SOC difference; wherein the SOC difference is the difference between the cut-off SOC and the starting SOC.

4. A battery management system, characterized in that: Including data analysis device, counter and controller: The data analysis device is used to determine the cycle life consumption value of each charging process based on the starting SOC and the ending SOC of each charging process of the battery; The counter is used to sum the cycle life consumption value during each charging process; The controller is configured to control the charging rate of the battery to be lower than a rate threshold if the sum of the cycle life consumption values ​​of each charging process is greater than the designed cycle life.

5. The battery management system according to claim 4, characterized in that: The data analysis device is used for: When the difference between the cut-off SOC and the starting SOC is the same, the greater the starting SOC is, the greater the determined cycle life consumption value is.

6. The battery management system according to claim 4, characterized in that: The data analysis device is used for: If the cut-off SOC is less than or equal to the minimum value of the SOC interval, the determined cycle life consumption value is less than the SOC difference value; If the starting SOC and the ending SOC are within the SOC range, the determined cycle life consumption value is equal to the SOC difference; If the starting SOC is greater than or equal to the maximum value of the SOC range, the determined cycle life consumption value is greater than the SOC difference; wherein the SOC difference is the difference between the cut-off SOC and the starting SOC.

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