Battery protection method and system and vehicle

Abstract

The invention discloses a battery protection method and system and a vehicle. The method comprises the steps that battery lithium precipitation is determined according to battery internal resistance when a battery is charged; and controlling the charging parameters of the battery when lithium is separated out from the battery. According to the battery protection method provided by the embodiment of the invention, the lithium precipitation of the battery can be determined according to the internal resistance of the battery in the battery charging process, so that the lithium precipitation of the battery can be determined in time, and the battery can be protected. And meanwhile, by controlling the charging parameters of the battery, the occurrence of further lithium precipitation can be effectively reduced or prevented.

Description

Technical Field

[0001] The present disclosure relates to a battery protection method, system and vehicle. Background Art

[0002] When the power batteries of new energy vehicles are fast charged (high current charging), lithium plating often occurs, which affects the electrochemical properties and battery safety inside the battery. Summary of the Invention

[0003] The present disclosure aims to provide a battery protection method, system and vehicle.

[0004] To achieve the above objectives, the present disclosure adopts the following technical solutions:

[0005] The present disclosure provides a battery protection method, comprising:

[0006] When the battery is charging, determining the lithium deposition of the battery based on the internal resistance of the battery; and

[0007] When the battery is undergoing lithium deposition, control the battery charging parameters.

[0008] In some embodiments, determining the battery lithium deposition based on the battery internal resistance includes: determining the battery lithium deposition based on a change in the battery internal resistance.

[0009] In some embodiments, determining the battery lithium deposition based on the change in the battery internal resistance includes: determining the battery lithium deposition based on the rate of change of the battery internal resistance.

[0010] In some embodiments, determining the battery lithium deposition according to the rate of change of the battery internal resistance includes: determining the battery lithium deposition when the absolute value of the rate of change of the battery internal resistance is greater than a rate of change threshold.

[0011] In some embodiments, determining the battery lithium deposition according to the change in the battery internal resistance includes: determining the battery lithium deposition when the absolute value of the change in the battery internal resistance is greater than a change threshold.

[0012] In some embodiments, the battery charging includes: charging the battery while the vehicle is parked or charging the battery while the vehicle is driving.

[0013] In some embodiments, charging the battery while the vehicle is traveling includes: charging the battery through braking feedback while the vehicle is traveling.

[0014] In some embodiments, controlling the charging parameters of the battery includes controlling the charging current or temperature of the battery.

[0015] In some embodiments, controlling the temperature of the battery includes:

[0016] When the battery temperature is less than or equal to a temperature threshold, increasing the battery temperature; and / or

[0017] When the battery temperature is greater than the temperature threshold, the battery temperature is reduced.

[0018] In some embodiments, controlling the charging current of the battery includes controlling the charging current of the battery to be a first charging current, where the first charging current is less than a normal charging current of the battery before lithium deposition.

[0019] In some embodiments, the first charging current is determined according to a normal charging current and a first coefficient.

[0020] In some embodiments, the first charging current is a product of a normal charging current and a first coefficient.

[0021] In some embodiments, the first coefficient is determined based on a second coefficient and a third coefficient, wherein the second coefficient is a safety coefficient and the third coefficient is a health coefficient.

[0022] In some embodiments, the first coefficient is the product of the second coefficient and the third coefficient.

[0023] In some embodiments, the second coefficient is determined based on a change in a battery parameter, a current battery temperature, a state of charge, and safety factor comparison data.

[0024] In some embodiments, the third coefficient is determined according to a battery state of health.

[0025] In some embodiments, the second coefficient is greater than or equal to 0 and less than or equal to 1; the third coefficient is greater than or equal to 0 and less than or equal to 1.

[0026] The battery protection method provided by the embodiments of the present disclosure can determine the occurrence of lithium deposition in the battery based on the battery's internal resistance during charging, thereby promptly identifying the occurrence of lithium deposition and enabling battery protection. Furthermore, by controlling the battery's charging parameters, further lithium deposition can be effectively reduced or prevented.

[0027] The present disclosure also provides a battery protection system, comprising a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of any one of the above methods.

[0028] The present disclosure also provides a computer-readable storage medium having a computer program / instruction stored thereon, which implements the steps of any of the above methods when executed by a processor.

[0029] The present disclosure also provides a computer program product, comprising a computer program / instruction, which implements the steps of any of the above methods when executed by a processor.

[0030] The present disclosure also provides a vehicle, comprising: a battery protection system as provided in any of the above embodiments.

[0031] The vehicle has the same structure and beneficial effects as described in any of the above embodiments, which will not be repeated here.

[0032] The above description is only an overview of the technical solution of the present disclosure. In order to more clearly understand the technical means of the present disclosure, 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 disclosure more obvious and easy to understand, the specific implementation methods of the present disclosure are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0034] Figure 1 is a flowchart of a battery protection method according to some embodiments;

[0035] Figure 2 is a diagram of an internal circuit of a battery according to some embodiments;

[0036] Figure 3 A diagram showing a battery internal resistance test according to some embodiments;

[0037] Figure 4 2 is a diagram of a battery internal resistance test according to some further embodiments. DETAILED DESCRIPTION

[0038] The following will be combined with the accompanying drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the embodiments described are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present disclosure.

[0039] In the description of the present disclosure, it should be understood that the terms "upper," "lower," "left," "right," "front," "back," "inner," "outer," and the like, indicating directions or positional relationships, are based on the directions or relative positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present disclosure and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific direction, be constructed, or operate in a specific direction. Therefore, they should not be construed as limitations on the present disclosure. Unless otherwise specified, the above-mentioned directional descriptions may be flexibly set in actual application, provided that the relative positional relationships shown in the accompanying drawings are met.

[0040] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this disclosure, unless otherwise specified, "plurality" means two or more.

[0041] In addition, in the specification and claims, "and / or" means at least one of the connected objects, and the character " / " generally indicates that the previous and subsequent related objects are in an "or" relationship.

[0042] In the description of this disclosure, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "electrically connected," and "connected" should be understood broadly. For example, they may refer to fixed electrical connections, detachable electrical connections, or integral electrical connections. They may be directly connected, indirectly connected through an intermediary, or internally connected between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure based on specific circumstances.

[0043] In the embodiments of the present disclosure, the terms "comprises", "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, article or device comprising a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, article or device comprising the element. In addition, it should be noted that the scope of the methods and devices in the embodiments of the present disclosure is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the opposite order according to the functions involved. For example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0044] In the embodiments of the present disclosure, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present disclosure should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0045] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0046] During rapid charging (high-current charging), lithium ions in new energy vehicles (NEVs) deposit on the surface of the negative electrode, causing lithium plating, a phenomenon known as lithium plating. This plating is manifested as a layer of silvery-white metallic lithium on the negative electrode surface. This abnormal lithium plating phenomenon can severely impact the battery's internal electrochemical properties and safety, thus affecting the vehicle's charge-discharge performance, cycle life, and safety. The likelihood of lithium plating increases, and the resulting hazards are greater, when the battery is at low temperatures, at a high state of charge (SOC), and at a low state of health (SOH).

[0047] Existing lithium plating detection methods primarily include offline and online testing. Offline detection primarily involves the three-electrode method, electrochemical reaction method, and disassembly method, while online detection primarily involves capacity decay and external sensing. These detection methods either require disassembling the battery for complex experiments and calculations, consuming significant time, manpower, and material resources. Alternatively, their use cases are limited, preventing real-time application for online testing on the entire vehicle and subsequent real-time charging optimization, impacting the performance and safety of new energy vehicle power batteries. Therefore, a fast and effective lithium plating detection method and charging optimization method are needed to avoid this situation.

[0048] In some embodiments, as Figure 1 As shown, the present disclosure provides a battery protection method, comprising:

[0049] When the battery is charging, determining the lithium deposition of the battery based on the internal resistance of the battery; and

[0050] When the battery is undergoing lithium deposition, control the battery charging parameters.

[0051] The battery protection method provided by the embodiments of the present disclosure can determine the occurrence of lithium deposition in the battery based on the battery's internal resistance during charging, thereby promptly identifying the occurrence of lithium deposition and enabling battery protection. Furthermore, by controlling the battery's charging parameters, further lithium deposition can be effectively reduced or prevented.

[0052] like Figure 2 As shown in Figure 1, when lithium plating occurs, it is equivalent to a resistor connected in parallel to the negative electrode surface. Figure 3 and 4 As shown, at this time, the total internal resistance will suddenly drop and the internal resistance change rate will suddenly increase. If the internal resistance change rate exceeds the preset standard internal resistance change rate value within this state range, it is determined in real time that lithium plating occurs.

[0053] in, Figure 3 The change in time and relative internal resistance at 25 degrees Celsius, 4C charging rate, and 0.1 second sampling period are shown, where the occurrence of internal resistance mutation is circled.

[0054] Figure 4 The changes in state of charge (SOC) and internal resistance at different charging rates, where the occurrence of internal resistance mutation is circled.

[0055] In order to quickly and practically determine the occurrence of lithium deposition, in some embodiments, determining the occurrence of lithium deposition based on the change in battery parameters includes: determining the occurrence of lithium deposition based on the change in battery internal resistance.

[0056] In some embodiments, determining the battery lithium deposition according to the change in the battery internal resistance includes: determining the battery lithium deposition according to the rate of change of the battery internal resistance.

[0057] In some embodiments, determining that battery lithium deposition occurs based on the rate of change of the battery internal resistance includes: determining that battery lithium deposition occurs when the absolute value of the rate of change of the battery internal resistance is greater than a rate of change threshold.

[0058] In some embodiments, determining that lithium deposition has occurred in the battery based on a change in the battery internal resistance includes: determining that lithium deposition has occurred in the battery when an absolute value of the change in the battery internal resistance is greater than a change threshold.

[0059] That is, whether the battery has lithium plating can be determined by the change in internal resistance during battery charging. When there is a sudden change in internal resistance, it can be determined that lithium plating has occurred.

[0060] In some embodiments, the battery charging includes: charging the battery while the vehicle is parked or charging the battery while the vehicle is driving.

[0061] In some embodiments, charging the battery while the vehicle is moving includes: charging the battery through braking feedback while the vehicle is moving.

[0062] For battery packs used in normal vehicle operation, the measurable parameters of the battery are limited; generally, the battery voltage, current, and temperature can be measured. Based on the voltage and current, the battery internal resistance can be calculated, and the presence of lithium deposition can be determined by sudden changes in the internal resistance. This allows for accurate determination of lithium deposition in the battery pack under limited measurable parameters. Compared to existing battery lithium deposition detection methods, the method disclosed herein is simpler and easier to implement, and can perform online testing of the entire vehicle battery pack.

[0063] When lithium deposition occurs in the battery, in order to reduce or prevent further lithium deposition, in some embodiments, controlling the charging parameters of the battery includes controlling the charging current or temperature of the battery.

[0064] That is, when lithium is deposited in the battery, by controlling the charging current or temperature of the battery, the further lithium deposition can be effectively reduced or prevented, thereby better protecting the battery.

[0065] To reduce or prevent further lithium plating, in some embodiments, controlling the battery temperature includes:

[0066] When the battery temperature is less than or equal to a temperature threshold, increasing the battery temperature; and / or

[0067] When the battery temperature is greater than the temperature threshold, the battery temperature is reduced.

[0068] That is, the battery temperature can be increased at low temperatures (such as increasing the battery heating amount), and the battery temperature can be lowered at high temperatures (such as increasing the battery cooling amount), so that the battery temperature can reach the appropriate temperature as quickly as possible, thereby reducing or preventing further lithium precipitation.

[0069] To better protect the battery and improve battery safety, in some embodiments, controlling the charging current of the battery includes: controlling the charging current of the battery to be a first charging current, where the first charging current is less than a normal charging current of the battery before lithium deposition.

[0070] That is, when lithium is deposited in the battery, further lithium deposition can be reduced or prevented by reducing the charging current, thereby protecting the battery and increasing the battery life and available capacity.

[0071] Those skilled in the art can reasonably configure the first charging current, such as setting the first charging current to one or more fixed current values, or a continuously changing current value, to protect the battery. To simplify control, in some embodiments, the first charging current is determined based on the normal charging current and the first coefficient.

[0072] The normal charging current may be a charging current when lithium deposition does not occur in the battery and other conditions are the same. The charging current may be determined using various existing technologies, which will not be described in detail here.

[0073] Table 1 below is a charging current table for a battery cell. The table shows the charging current values at different SOC (state of charge) and temperatures. The normal charging current at this time can be determined by looking up the table based on the current SOC and temperature of the battery.

[0074]

[0075] Table 1 Charging current table of a certain battery cell

[0076] To simplify control and reasonably determine the first charging current, in some embodiments, the first charging current is the product of the normal charging current and a first coefficient.

[0077] The charging current after lithium deposition can be controlled by reasonably controlling the first coefficient, thereby protecting the battery safety and maximizing the charging power.

[0078] In order to reasonably determine the first charging current, in some embodiments, the first coefficient is determined based on the second coefficient and the third coefficient, where the second coefficient is a safety coefficient and the third coefficient is a health coefficient.

[0079] Those skilled in the art may determine the first coefficient according to the second coefficient and the third coefficient in various appropriate ways. In some embodiments, the first coefficient is the product of the second coefficient and the third coefficient.

[0080] In some embodiments, the second coefficient is determined based on the variation of the battery parameter, the current temperature and state of charge of the battery, and safety factor comparison data.

[0081] In some embodiments, the third coefficient is determined based on the battery state of health.

[0082] In some embodiments, the safety factor may be a factor set based on a comprehensive consideration of the rate of change of the battery's internal resistance, the state of charge, and the temperature in order to ensure battery safety while ensuring continued charging.

[0083] The health factor may be a factor determined according to the battery health state. In some embodiments, the health factor is the battery health state.

[0084] In some embodiments, the second coefficient is greater than or equal to 0 and less than or equal to 1; the third coefficient is greater than or equal to 0 and less than or equal to 1.

[0085]

[0086] Table 2 Safety factor α at different temperatures and state of charge (SOC)

[0087] Table 2 above shows the safety factor at different temperatures and states of charge (SOC) under a certain internal resistance change rate. The safety factor at this time can be determined by looking up the table based on the current SOC and temperature of the battery.

[0088] The present disclosure provides a battery protection method, wherein the temperature, state of charge, state of health, and internal resistance change of each single cell in the battery pack when the vehicle is plugged in for charging or receiving charging pulse feedback during driving are monitored to determine the internal resistance change rate of each single cell under the current temperature, state of charge, and state of health (the internal resistance can be directly calculated by dividing the voltage by the current, and the internal resistance change rate is the absolute value of the differential of the internal resistance and time at this time |δR / δt|). When lithium plating occurs, it is equivalent to connecting a resistor in parallel to the negative electrode surface, resulting in a sudden decrease in the total internal resistance and a sudden increase in the internal resistance change rate. If the internal resistance change rate exceeds the preset standard internal resistance change rate value within this state range, lithium plating is determined in real time.

[0089] At the same time, when the vehicle is plugged in for charging or driving, the charging feedback determines that lithium deposition has occurred. The safety factor value under this state is obtained by looking up the table (such as Table 2), and the charging current is immediately adjusted to the safe current I 安全 , to prevent lithium plating reaction from continuing to occur. The safety current is the safety factor α (α < 100%) that takes into account the internal resistance change rate, temperature and charge state under the current state, multiplied by the current value corresponding to the charging current table A (such as Table 1) at the current temperature and charge state and the health factor β (battery health state), I 安全 =α×β×I A表 By reducing the charging current and avoiding lithium plating, the performance and safety protection of the power battery can be guaranteed in real time.

[0090] The battery protection method provided by the embodiments of the present disclosure can determine the occurrence of lithium deposition in the battery based on the battery's internal resistance during charging, thereby promptly identifying the occurrence of lithium deposition and enabling battery protection. Furthermore, by controlling the battery's charging parameters, further lithium deposition can be effectively reduced or prevented.

[0091] The present disclosure also provides a battery protection system, including a memory, a processor, and a computer program stored in the memory, wherein the normal charging current processor executes the computer program to implement the steps of any one of the above methods.

[0092] The present disclosure also provides a computer-readable storage medium having a computer program / instruction stored thereon, which implements the steps of any of the above methods when the computer program / instruction is executed by a processor.

[0093] The present disclosure also provides a computer program product, comprising a computer program / instruction, which implements the steps of any of the above methods when executed by a processor.

[0094] The present disclosure also provides a vehicle, comprising: a battery protection system as provided in any of the above embodiments.

[0095] The vehicle has the same structure and beneficial effects as any of the above embodiments, which will not be described again here.

[0096] The embodiments of the present disclosure are described above in conjunction with the accompanying drawings, but the present disclosure is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present disclosure, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present disclosure and the claims, all of which are protected by the present disclosure.

Claims

1. A battery protection method, characterized in that: include: When the battery is charging, the lithium deposition of the battery is determined based on the internal resistance of the battery; as well as When the battery is undergoing lithium deposition, control the battery charging parameters.

2. The battery protection method according to claim 1, wherein: Determining the battery lithium deposition according to the battery internal resistance includes: determining the battery lithium deposition according to a change in the battery internal resistance.

3. The battery protection method according to claim 2, wherein: Determining the battery lithium deposition according to the change in the battery internal resistance includes: determining the battery lithium deposition according to the change rate of the battery internal resistance.

4. The battery protection method according to claim 3, wherein: Determining the battery lithium deposition according to the rate of change of the battery internal resistance includes: determining the battery lithium deposition when the absolute value of the rate of change of the battery internal resistance is greater than a rate of change threshold.

5. The battery protection method according to claim 2, wherein: Determining the battery lithium deposition according to the change in the battery internal resistance includes: determining the battery lithium deposition when the absolute value of the change in the battery internal resistance is greater than a change threshold.

6. The battery protection method according to claim 1, wherein: The battery charging includes: charging the battery when the vehicle is parked or charging the battery when the vehicle is driving.

7. The battery protection method according to claim 6, characterized in that: The battery charging while the vehicle is running includes: braking feedback to charge the battery while the vehicle is running.

8. The battery protection method according to claim 1, wherein: Controlling the charging parameters of the battery includes controlling the charging current or temperature of the battery.

9. The battery protection method according to claim 8, characterized in that: Controlling the temperature of the battery includes: When the battery temperature is less than or equal to a temperature threshold, increasing the battery temperature; and / or When the battery temperature is greater than the temperature threshold, the battery temperature is reduced.

10. The battery protection method according to claim 8, characterized in that: Controlling the charging current of the battery includes controlling the charging current of the battery to be a first charging current, where the first charging current is less than a normal charging current of the battery before lithium deposition.

11. The battery protection method according to claim 10, wherein: The first charging current is determined according to a normal charging current and a first coefficient.

12. The battery protection method according to claim 11, wherein: The first charging current is a product of a normal charging current and a first coefficient.

13. The battery protection method according to claim 11, wherein: The first coefficient is determined based on the second coefficient and the third coefficient, wherein the second coefficient is a safety coefficient and the third coefficient is a health coefficient.

14. The battery protection method according to claim 13, wherein: The first coefficient is the product of the second coefficient and the third coefficient.

15. The battery protection method according to claim 13, wherein: The second coefficient is determined based on the variation of the battery parameters, the current temperature of the battery, the state of charge and the safety factor comparison data.

16. The battery protection method according to claim 13, wherein: The third coefficient is determined according to the battery health state.

17. The battery protection method according to claim 13, wherein: The second coefficient is greater than or equal to 0 and less than or equal to 1; the third coefficient is greater than or equal to 0 and less than or equal to 1.

18. A battery protection system comprising a memory, a processor, and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 17.

19. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 17 are implemented.

20. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 17 are implemented.

21. A vehicle, characterized in that: Comprising the battery protection system as claimed in claim 18.

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