A battery management system and a method for assessing battery corrosion status.

Abstract

This invention provides a battery management system and a method for assessing battery corrosion status, applicable to the field of lithium battery technology. The battery management system is configured to perform the following steps: controlling a first circuit to connect the negative electrode of a target battery to the battery casing, and monitoring a first voltage between the negative electrode and the casing; when the first voltage drops to a preset value, controlling a second circuit to connect the positive electrode of the target battery to the casing; determining a first charge transfer amount flowing through a first resistor, and determining a second charge transfer amount flowing through a second resistor; and assessing whether casing corrosion has occurred in the target battery based on the first and second charge transfer amounts. This approach, by applying external electrical disturbances to the battery casing in stages and measuring the charge transfer amount, can indirectly quantify the amount of charge related to corrosion, thereby accurately assessing the corrosion status of the battery casing and providing early warning of corrosion failure risks.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically to a battery management system and a method for assessing battery corrosion status. Background Technology

[0002] Lithium-ion batteries, as crucial energy storage components, are widely used in electric vehicles, energy storage systems, and portable electronic devices, making their long-term reliability paramount. However, for lithium-ion batteries with aluminum casings, electrochemical corrosion inside the casing is difficult to detect in the short term and usually does not immediately affect the battery's charge and discharge performance, thus easily overlooked. But if corrosion leads to cell leakage, it can cause insulation failure, and in severe cases, even short circuits, potentially leading to combustion and explosion, posing a significant safety hazard.

[0003] In existing technologies, the detection of battery corrosion status typically relies on accelerated simulation tests and post-mortem analysis. This involves short-circuiting the battery's negative terminal and the battery casing, waiting for the casing to corrode, and then disassembling the corroded battery to conduct a corrosion assessment. This determines the corrosion resistance of the battery casing material under specific conditions, but it does not allow for direct assessment of the battery's corrosion status. Therefore, how to provide early warning of corrosion failure risks during normal battery service or testing without damaging the battery structure has become a pressing technical problem in this field. Summary of the Invention

[0004] In view of this, the present invention aims to provide a battery management system and a method for assessing battery corrosion status, so as to solve the problem that current detection methods are difficult to assess the charge information directly related to the internal corrosion process of the battery casing without damaging the battery structure during normal battery service or testing, thereby realizing quantitative early warning of corrosion failure risk.

[0005] In one aspect, the present invention provides a battery management system configured to perform the following steps: A control first circuit connects the negative terminal of the target battery and the casing of the target battery, and monitors a first voltage between the negative terminal and the casing. The first circuit includes at least a first resistor. When the first voltage drops to a preset value, the control second circuit connects the positive terminal of the target battery and the casing. The second circuit includes at least a second resistor. Determine the first charge transfer amount flowing through the first resistor during the period when the first voltage drops from the initial voltage value to the preset value, and determine the second charge transfer amount flowing through the second resistor during the period when the first voltage recovers from the preset value to the initial voltage value before connecting the first resistor; The corrosion charge of the target battery is determined based on the first charge transfer amount and the second charge transfer amount. The corrosion charge is used to assess whether the target battery has experienced casing corrosion.

[0006] Secondly, embodiments of this application provide a method for evaluating the corrosion state of a battery, including: A first circuit is connected to the negative terminal of the target battery and the casing of the target battery to monitor a first voltage between the negative terminal and the casing. The first circuit includes at least a first resistor. When the first voltage drops to a preset value, the second circuit is connected to the positive terminal of the target battery and the casing, the second circuit including at least a second resistor; The first charge transfer amount flowing through the first resistor when the first voltage drops to a preset value, and the second charge transfer amount flowing through the second resistor when the first voltage recovers to the initial voltage value before connecting the first circuit; The corrosion charge of the target battery is determined based on the difference between the first charge transfer amount and the second charge transfer amount. The corrosion charge is used to evaluate the corrosion state of the target battery casing.

[0007] Thirdly, embodiments of this application provide a method for evaluating the corrosion state of a battery pack, including: Each battery in the battery pack is taken as a target battery, and its corresponding corrosion charge is determined. The maximum value among the corrosion charges is taken as the corrosion charge of the battery pack; The corrosion status of the battery pack is assessed based on the corrosion charge of the battery pack. The corrosion charge corresponding to each of the batteries is obtained using the following method: A first circuit is connected to the negative terminal of the target battery and the casing of the battery pack, and the impedance between the batteries other than the target battery and the casing is not less than a threshold. A first voltage between the negative terminal and the casing is monitored. The first circuit includes at least a first resistor. When the first voltage reaches a preset value, the second circuit is connected to the positive terminal of the target battery and the casing, and the second circuit includes at least a second resistor; The first charge transfer amount flowing through the first resistor when the first voltage drops to a preset value, and the second charge transfer amount flowing through the second resistor when the first voltage recovers to the initial voltage value before connecting the first circuit; The corrosion charge of the battery pack is determined based on the difference between the first charge transfer amount and the second charge transfer amount, and the corrosion charge is used to assess the corrosion status of the battery pack.

[0008] Fourthly, embodiments of this application provide a method for evaluating the corrosion state of a battery pack, including: Each battery in the battery pack is taken as a target battery, and its corresponding corrosion charge is determined. The maximum value among the corrosion charges is taken as the corrosion charge of the battery pack; The corrosion status of the battery pack is assessed based on the corrosion charge of the battery pack. The corrosion charge corresponding to each of the batteries is obtained using the following method: A first circuit is connected to the negative terminal of the target battery and the casing of the battery pack, and the impedance between the batteries other than the target battery and the casing is not less than a threshold. A first voltage between the negative terminal and the casing is monitored. The first circuit includes at least a first resistor. When the first voltage reaches a preset value, the second circuit is connected to the positive terminal of the target battery and the casing, and the second circuit includes at least a second resistor; The first charge transfer amount flowing through the first resistor when the first voltage drops to a preset value, and the second charge transfer amount flowing through the second resistor when the first voltage recovers to the initial voltage value before connecting the first circuit; The corrosion charge of the battery pack is determined based on the difference between the first charge transfer amount and the second charge transfer amount, and the corrosion charge is used to assess the corrosion status of the battery pack.

[0009] According to embodiments of this application, circuits are connected in stages between the negative electrode and the casing, and between the positive electrode and the casing, to change the casing potential and monitor the resulting charge transfer. The circuits actively induce or compensate for charge flow related to the internal corrosion process, and the corrosion charge amount used for assessment is determined by measuring the first and second charge transfer amounts. This enables non-destructive assessment of the internal corrosion charge of the battery, accurately predicting the risk of battery corrosion failure, and providing a reliable basis for battery safety management and lifespan prediction. Attached Figure Description

[0010] Figure 1 This is a schematic flowchart illustrating the battery corrosion state assessment method provided in this application embodiment.

[0011] Figure 2 This is a schematic diagram of a circuit structure for evaluating the corrosion state of a battery, provided as an embodiment of this application.

[0012] Figure 3 This is a schematic diagram of the variation curves of various parameters of the target battery in a single battery corrosion state, provided as an embodiment of this application.

[0013] Figure 4This is a schematic diagram of the voltage and current variation curves between the negative electrode and the casing, provided as an embodiment of this application.

[0014] Figure 5 This is a schematic diagram of a method for evaluating the corrosion status of a battery or battery pack, provided in an embodiment of this application.

[0015] Figure 6 This is a schematic diagram of a battery corrosion assessment device provided in this specification.

[0016] Figure 7 A method based on the embodiments of this application is provided. Figure 1 A schematic diagram of the electronic device using the method shown. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0018] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0019] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0020] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0021] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0022] Lithium-ion batteries, as important energy storage components, are widely used in electric vehicles, energy storage systems, and portable electronic devices, and their long-term reliability is crucial. However, especially for batteries with aluminum casings, when the casing potential reaches the corrosion potential, if the aluminum casing forms an electron channel in contact with the negative electrode, and the electrolyte provides an ion pathway in contact with the aluminum casing, lithium ions will embed into the aluminum casing, forming a porous aluminum-lithium alloy. In other words, electrochemical corrosion will occur at the interface between the inner wall of the casing and the electrolyte.

[0023] The circuit for this corrosion reaction is connected in parallel with the battery's main circuit. However, due to its high internal resistance, the resulting corrosion current is extremely weak and easily mixed in with normal charging / discharging current or noise, making it undetectable. Electrochemical corrosion inside the casing is difficult to detect in the short term and usually does not immediately affect the battery's charging / discharging performance, thus it is easily overlooked. However, cell leakage can cause insulation failures, and in severe cases, can even lead to short circuits, combustion, and explosion, posing significant safety hazards.

[0024] Currently, the assessment of battery corrosion status typically relies on accelerated simulation tests and post-mortem analysis. This involves short-circuiting the battery's negative terminal and the battery casing, waiting for the casing to corrode through, and then disassembling the corroded battery to conduct a corrosion assessment. This determines the corrosion resistance of the battery casing material under specific conditions, but it cannot directly assess the battery's corrosion status. However, the corrosion of the aluminum casing inside the battery is a continuous and slow electrochemical process. The risk lies not only in whether the insulation fails, but also in the degree of corrosion accumulation.

[0025] Therefore, how to assess and provide early warning of corrosion risks inside the battery casing without damaging the battery structure during normal service or testing has become a specific technical problem that urgently needs to be solved in this field.

[0026] Based on this, this application provides a battery management system (BMS) that can be installed on a battery, connected to an electric device, or communicate with the battery to control or manage it. The BMS is configured to perform the following steps to assess the casing corrosion state of the target battery. To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1 As shown, Figure 1 This is a schematic flowchart illustrating the battery corrosion state assessment method provided in this application embodiment. It includes the following steps: S100: Connect a first circuit to the negative terminal of the target battery and the casing of the target battery, and monitor a first voltage between the negative terminal and the casing, wherein the first circuit includes at least a first resistor.

[0028] In one or more embodiments of this application, the specific type of device that performs the detection step, such as the BMS, is not limited. The BMS can be a microcontroller unit (MCU), a system on a chip (SoC), a microprocessor unit (MPU), a multi-sensor fusion chip, etc. This application does not impose any restrictions on this and the BMS can be set according to actual needs.

[0029] To assess the corrosion state of the target battery casing, the BMS can first introduce an external circuit to actively change the potential relationship between the casing and the negative electrode, inducing the flow of charges related to the internal corrosion process of the target battery in the external circuit, thereby converting the amount of corrosion charge inside the battery, which is difficult to measure directly, into the amount of charge transfer that can be accurately measured externally.

[0030] Specifically, the BMS issues control commands to connect the first circuit to the negative terminal of the target battery and the battery casing. At this time, a potential difference exists between the casing and the negative terminal, forming a current path. Charge will be transferred through the first circuit and any existing internal pathways, causing a change in the voltage between the negative terminal and the casing, i.e., the first voltage. This change in the first voltage is then monitored.

[0031] It should be noted that, in one or more embodiments of this application, the method by which the BMS connects the first circuit to the negative terminal and casing of the target battery is not limited. For example, it can be achieved by controlling the on / off state of a switch on the first circuit. For instance, the switch on the first circuit can be a metal-oxide-semiconductor field-effect transistor, whose gate is controlled by a digital signal from the processing unit, thus achieving fast, contactless switching. Of course, it can also be a mechanical relay, an optocoupler relay, an analog switch chip, etc., and this application does not impose any limitations on this.

[0032] Furthermore, the first circuit refers to a circuit including a fixed resistor or an adjustable resistor, a circuit including a switching element to control on / off switching, a circuit including a current monitoring module, or a combination of at least two of these circuits. The target battery casing generally refers to the metal outer shell or packaging structure of the battery, which is in contact with the internal electrodes and electrolyte and may participate in electrochemical corrosion reactions, such as an aluminum casing, an aluminum alloy casing, a steel casing, or a common conductive casing for a battery pack or battery assembly, or a combination thereof.

[0033] S102: When the first voltage drops to a preset value, the second circuit is connected to the positive terminal of the target battery and the casing, wherein the second circuit includes at least a second resistor.

[0034] Since the first resistor connects the negative terminal and the casing, the loop current mainly consists of two parts: the corrosion current and the charging and discharging current of the parasitic capacitance between the casing and the electrode. In order to determine the accurate corrosion charge, when the first voltage drops to a preset value, the BMS controls the second circuit to connect the positive terminal and the casing. Based on the principle that the net charge change is zero after the capacitor completes a full point cycle, the accurate corrosion charge is obtained.

[0035] The second circuit refers to a circuit including a fixed resistor or an adjustable resistor, a circuit including a switching element to control on / off switching, a circuit including a current monitoring module, or a combination of at least two of these circuits. It should be noted that in one or more embodiments of this application, the method by which the BMS connects the second circuit to the positive terminal and casing of the target battery is not limited; reference can be made to the description of the connection method for the first circuit described above, which will not be repeated here.

[0036] It should also be noted that, in one or more embodiments of this application, the preset value refers to a predefined fixed voltage value, a value calculated based on the initial voltage percentage of the battery, or a stable value determined experimentally that significantly reduces the casing potential. This application does not limit how the preset value is specifically determined, and it is generally set between 0.05 volts and 0.15 volts, for example, 0.06 volts.

[0037] S104: Determine the first charge transfer amount flowing through the first resistor when the first voltage drops to a preset value, and the second charge transfer amount flowing through the second resistor when the first voltage recovers to the initial voltage value before connecting the first circuit.

[0038] In order to determine the corrosion state of the target battery casing, i.e. to calculate the corrosion charge of the target battery, the BMS can first determine the total amount of charge transferred in the first circuit and the second circuit after connecting the first circuit and the second circuit.

[0039] Specifically, the BMS can first determine the amount of charge transferred through the first resistor during the period when the first voltage drops from the initial voltage value to a preset value. Of course, in one or more embodiments of this application, the specific method by which the BMS determines the amount of charge transferred is not limited. It can be determined by integrating the current flowing through the first resistor during this period, or by determining the voltage change across the first resistor during this period, calculating the current based on the resistance value, and then integrating the result. Under specific conditions, a coulomb counter chip can also be used for direct measurement. Since there are many possible solutions, this application does not list them all; the specific method can be set according to actual needs.

[0040] Similarly, the same method as for calculating the first charge transfer amount can be used when calculating the second charge transfer amount. For example, the current flowing through the second resistor during the period when the first voltage recovers from a preset value to the initial voltage value before connecting the first resistor can be determined, and then the current can be integrated over time to determine the second charge transfer amount. This application does not impose any restrictions on this and can set it according to actual needs.

[0041] It should be noted that, in one or more embodiments of this application, the initial voltage value refers to the initial voltage state between the negative electrode of the battery and the casing before the battery is connected to the first circuit and the second circuit, including but not limited to the voltage value measured instantaneously before connecting to the first circuit, or the average voltage over a period of stable time before connecting to the first circuit.

[0042] like Figure 2 As shown, Figure 2 This application provides a schematic diagram of a circuit structure for evaluating the corrosion state of a battery. The first circuit includes a first resistor R1, which is connected to the negative terminal and the casing of the target battery. The second circuit includes a second resistor R2, which is connected to the positive terminal and the casing of the target battery. Then, a measuring device is used to measure the voltage of R1 (the first voltage) and the voltage of R2 to subsequently determine the corrosion charge of the target battery.

[0043] It should be noted that the measuring device can also be a measuring circuit connected to the first circuit and the second circuit respectively, rather than an external measuring device. This application does not limit this and can be set according to actual needs.

[0044] In addition, such as Figure 3 As shown, Figure 3 This is a schematic diagram of the change curves of various parameters of the target battery in a single battery corrosion state provided in an embodiment of this application. The horizontal axis represents time, the left vertical axis represents voltage, and the right vertical axis represents current. The figure includes four curves, namely negative electrode-casing voltage, positive electrode-casing voltage, negative electrode-casing current, and positive electrode-casing current. Each curve represents the change trend of current and voltage flowing through R1 and R2 after short-circuiting the second resistor R2 between the positive electrode and the casing.

[0045] S106: Determine the corrosion charge of the target battery based on the first charge transfer amount and the second charge transfer amount. The corrosion charge is used to assess whether the target battery has experienced casing corrosion.

[0046] To correlate the measured charge transfer amount with the internal corrosion state of the target battery and thus derive an evaluation result, this BMS can determine the corrosion charge of the target battery based on the acquired first and second charge transfer amounts. The corrosion charge refers to the charge quantity parameter used to assess the electrochemical corrosion occurring within the target battery casing, and is positively correlated with the actual degree of internal corrosion.

[0047] Specifically, the difference between the second charge transfer amount and the first charge transfer amount is calculated, and then the difference is used as the corrosion charge to determine the charge component contributed by the electrochemical process inside the target battery.

[0048] Of course, the BMS can also use other functional relationships to calculate the corrosion charge, such as f(Q1, Q2). This function can be calibrated through a large amount of experimental data to improve the evaluation accuracy or adapt to different battery models.

[0049] Then, the BMS can determine whether there is internal corrosion in the target battery based on the determined corrosion charge.

[0050] For example, the risk of casing corrosion of the target battery can be determined by the change between the corrosion charge determined at the current moment and the corrosion charge determined most recently. When the change exceeds a certain threshold, the target battery is considered to have a risk of casing corrosion. If the change is less than the preset threshold, the target battery is determined to currently not have a risk of casing corrosion.

[0051] Alternatively, the corrosion charge of the target battery can be determined at the time of manufacture. Then, when assessing the corrosion status of the target battery, the current corrosion charge is determined and compared with the corrosion charge at the time of manufacture. If the difference exceeds a threshold, the target battery is considered to have a risk of casing corrosion; if it does not exceed the threshold, the target battery is considered not to have a risk of casing corrosion. There are many assessment methods, and this application does not limit this one; it can be set according to actual needs.

[0052] Alternatively, it can be directly determined whether the corrosion charge exceeds a threshold. If so, it is determined that the target battery has casing corrosion; otherwise, it is determined that the risk of the target battery having casing corrosion is low.

[0053] It should be noted that, in one or more embodiments of this application, the method of determining the above threshold is not limited. Generally, it is determined based on the target battery model, design life, and safety margin. Of course, it can also be set by manual experience or other means. This application does not impose any restrictions on this, and it can be set according to actual needs.

[0054] In such Figure 1The assessment method described involves connecting circuits between the battery's negative electrode and the casing, and between the positive electrode and the casing, in stages. This alters the casing potential and monitors the resulting charge transfer. The circuits actively induce or compensate for charge flow associated with the internal corrosion process. By measuring the first and second charge transfer amounts, the corrosion charge used for assessment is determined. This enables a non-destructive assessment of the battery's internal corrosion charge, accurately predicting the risk of battery corrosion failure and providing a reliable basis for battery safety management and lifespan prediction.

[0055] Furthermore, before controlling the first circuit to connect the negative terminal of the target battery to its casing, the BMS is configured to determine the resistance values ​​of the first resistor and the second resistor based on the initial state parameters of the target battery. These initial state parameters include the open-circuit voltage of the target battery and the initial voltage value before the negative terminal is connected to the first circuit. Dynamically calculating a suitable test resistor based on the instantaneous state of the target battery ensures a safe, controllable testing process and generates effective voltage changes.

[0056] Specifically, the BMS first measures the open-circuit voltage of the target battery and the initial voltage between the negative electrode and the casing. This ensures that the subsequently determined first resistor can reduce the voltage between the negative electrode and the casing to a lower, preset target value. Then, an approximate formula for calculating the first resistor is derived based on Kirchhoff's laws. Of course, to simplify the calculation, the BMS can ignore the internal resistance of the target battery; for example, the casing can be considered a floating ground node, connected to the negative electrode via the first resistor, forming a network consisting of the battery open-circuit voltage, the negative electrode-casing insulation resistance, and the first resistor. However, to protect the target battery, the value of the first resistor is generally matched to the insulation resistance of the target battery; that is, the first resistor is considered a resistor in parallel with the insulation resistance, and then its value is determined according to Kirchhoff's laws.

[0057] Similarly, the same method can be used to calculate the resistance of the second resistor as to calculate the resistance of the first resistor. Please refer to the description of the steps for determining the first resistor above; it will not be repeated here.

[0058] For example, if the voltage between the negative terminal of the battery and the casing is 2.2V and the open circuit voltage is 3.247V, then the first resistance can be calculated to be 998.7Ω and the second resistance to be 468Ω using Kirchhoff's laws.

[0059] Of course, a pre-stored resistance value table can be directly accessed based on the battery model, or a digital potentiometer with automatically adjustable resistance can be used to determine the appropriate resistance value through a small trial current in the initial testing phase. This application does not impose any restrictions on this; the setting can be adjusted according to actual needs.

[0060] Furthermore, since the electrochemical corrosion of a battery is a chemical process, its reaction rate is affected by temperature; generally, the corrosion reaction accelerates with increasing temperature. To improve the accuracy and consistency of evaluation results across different temperature environments, this BMS can perform temperature compensation when determining the corrosion charge. For example, it can correct the measured charge using a preset compensation function, making the corrosion charge comparable at different temperatures. In other words, it maps the corrosion charge measured at different temperatures to a uniform ambient temperature.

[0061] Specifically, this BMS can monitor the temperature of the target battery through sensors, then determine the corrosion charge compensation amount based on the temperature, and further determine the corrosion charge of the target battery using the corrosion charge compensation amount, the first charge transfer amount, and the second charge transfer amount. For example, the corrosion charge compensation amount can be calculated using a preset compensation function. This compensation function can be derived based on fitting a large amount of experimental data, such as inputting the current temperature and a unified reference temperature, and outputting the corresponding compensation coefficient or specific compensation value.

[0062] Of course, the BMS can also determine the corrosion charge compensation amount through a pre-trained model. This model can be a neural network model, which automatically outputs a more accurate corrosion charge compensation amount by inputting the target temperature and the actual ambient temperature, reducing the error of manually fitting the compensation function. The target temperature can be the rated temperature calibrated at the factory or the ambient temperature at the time of the most recent battery corrosion status assessment. This application does not impose any restrictions on this and it can be set according to actual needs.

[0063] By correcting the systematic measurement errors introduced by changes in ambient temperature or the battery's own operating temperature through corrosion charge compensation, the interference of environmental factors on corrosion charge assessment is reduced, making the assessment results more realistically reflect the internal corrosion state of the battery, and making the assessment results more comparable and reliable.

[0064] Furthermore, it should be noted that in one or more embodiments of this application, the BMS is not limited in how it determines whether to perform a corrosion state assessment of the target battery. It can be performed in response to an assessment command or by manual operation. Alternatively, it can be performed according to a preset cycle. This execution cycle can be fixed or adjusted according to conditions such as a decline in battery health or an increase in the number of charge-discharge cycles. For example, the execution cycle may be negatively correlated with the number of charge-discharge cycles, battery health, and the most recently determined corrosion charge of the target battery.

[0065] Furthermore, the BMS can also set multiple preset intervals, determining the corresponding execution cycle based on the preset interval in which the corrosion charge falls. Specifically, taking two preset intervals as an example, when the corrosion charge of the target battery is within the first preset interval, the corrosion status of the target battery is reassessed at a first preset time interval. When the corrosion charge of the target battery is within the second preset interval, the corrosion status of the target battery is reassessed at a second preset time interval. The maximum value of the first preset interval is not greater than the minimum value of the second preset interval, and the first preset time interval is greater than the second preset time interval.

[0066] Furthermore, to reduce or eliminate the residual impact on the target battery's performance after the first and second circuits are connected, the second circuit and voltage monitoring device are removed when the first voltage between the negative electrode and the casing returns to its initial value. Then, the disconnection time of the first circuit is set according to actual needs. For example, the BMS can also disconnect the first and second circuits after measuring the corrosion charge.

[0067] To further reduce any residual impact on the performance of the target battery, the BMS can also charge and discharge the target battery at a low rate after disconnecting the first and second circuits and allowing it to stand for a period of time until the open-circuit voltage of the target battery returns to its initial state.

[0068] It should be noted that the aforementioned resting time and charge / discharge rate are usually set according to the type and capacity of the target battery. For example, a large-capacity battery may require a longer resting time and a lower charge / discharge rate, while a small-capacity battery can have a shorter resting time and a slightly higher charge / discharge rate. The application itself does not impose any restrictions on this and can be set according to actual needs.

[0069] like Figure 4 As shown, Figure 4 This is a schematic diagram of the voltage and current variation curves between the negative electrode and the casing provided in an embodiment of this application, wherein each fluctuation corresponds to an assessment of the battery corrosion state.

[0070] Based on the above, this application also provides a method for assessing the corrosion state of a battery or battery pack, such as... Figure 5 As shown, Figure 5 A schematic diagram of a method for assessing the corrosion state of a battery or battery pack provided in this application embodiment includes: S500: Take each battery in the battery pack or battery group as the target battery and determine the corresponding corrosion charge; S502: Take the maximum value among the corrosion charges as the corrosion charge of the battery pack or battery group; S504: Evaluate the corrosion status of the battery pack based on the corrosion charge of the battery pack; The corrosion charge corresponding to each of the batteries is obtained using the following method: S506: Connect the first circuit to the negative terminal of the target battery and the housing of the battery pack or battery group, and ensure that the impedance between the battery other than the target battery and the housing is not less than a threshold, monitor the first voltage between the negative terminal and the housing, wherein the first circuit includes at least a first resistor; It should be noted that, in one or more embodiments of this application, the specific method used by the BMS to disconnect other batteries from the casing is not limited. For example, it could be achieved through a switch matrix pre-set on the battery pack or battery module, with one switch corresponding to each battery. Once the target battery is identified, the switches of the other batteries are disconnected to ensure electrical isolation between the other batteries and the casing. Since there are many possible methods, this application does not impose any limitations and the method can be set according to actual needs.

[0071] S508: When the first voltage reaches a preset value, the second circuit is connected to the positive terminal of the target battery and the casing, wherein the second circuit includes at least a second resistor; S510: Determine the first charge transfer amount flowing through the first resistor when the first voltage drops to a preset value, and the second charge transfer amount flowing through the second resistor when the first voltage recovers to the initial voltage value before connecting the first circuit; S512: Determine the corrosion charge of the battery pack or battery group based on the difference between the first charge transfer amount and the second charge transfer amount, wherein the corrosion charge is used to assess the corrosion status of the battery pack or battery group.

[0072] It should be noted that, in one or more embodiments of this application, the method for assessing the corrosion state of the battery pack or battery group is not limited to which specific device performs the assessment. It can be performed by the control system of the battery pack or battery group, distributed by the BMS of each battery within the battery pack or battery group, or performed by the BMS of the main battery of the battery pack or battery group. There are many possible solutions, which are not listed here; the specific method can be set according to actual needs.

[0073] Based on the battery corrosion state assessment method provided in one or more embodiments of this specification, this specification also provides a corresponding battery corrosion state assessment device, such as... Figure 6 As shown.

[0074] Figure 6 This is a schematic diagram of a battery corrosion state assessment device provided in this specification, specifically including: A first control module 600 is used to connect a first circuit to the negative terminal of a target battery and the casing of the target battery, and to monitor a first voltage between the negative terminal and the casing. The first circuit includes at least a first resistor. The second control module 601 is used to connect the second circuit to the positive terminal of the target battery and the casing when the first voltage drops to a preset value. The second circuit includes at least a second resistor. The determining module 602 is used to determine the first charge transfer amount flowing through the first resistor when the first voltage drops to a preset value, and the second charge transfer amount flowing through the second resistor when the first voltage recovers to the initial voltage value before connecting the first circuit; Evaluation module 603 is used to determine the corrosion charge of the target battery based on the first charge transfer amount and the second charge transfer amount, wherein the corrosion charge is used to evaluate whether the target battery has experienced casing corrosion.

[0075] Optionally, the device further includes a calculation module 604, specifically configured to determine the resistance values ​​of the first resistor and the second resistor based on the initial state parameters of the target battery, wherein the initial state parameters include the open-circuit voltage of the target battery and the initial voltage value before the negative terminal is connected to the first circuit.

[0076] Optionally, the determining module 602 is specifically used to determine the current flowing through the first resistor during the period when the first voltage drops from the initial voltage value to the preset value; and to determine the first charge transfer amount flowing through the first resistor based on the integration of the current flowing through the first resistor and the time.

[0077] Optionally, the determining module 602 is specifically used to determine the current flowing through the second resistor during the period when the first voltage recovers from the preset value to the initial voltage value before the first resistor is connected; and to determine the second charge transfer amount flowing through the second resistor based on the integration of the current flowing through the second resistor and the time.

[0078] Optionally, the evaluation module 603 is specifically used to monitor the temperature of the target battery; determine the corrosion charge compensation amount based on the temperature; and determine the corrosion charge of the target battery based on the corrosion charge compensation amount, the first charge transfer amount, and the second charge transfer amount.

[0079] Optionally, the evaluation module 603 is specifically used to determine the corrosion charge compensation amount based on the temperature and a preset compensation function, wherein the compensation function is obtained in advance by fitting experimental data of multiple batteries at different temperatures.

[0080] Optionally, the evaluation module 603 is specifically used to input the temperature and target temperature into a pre-trained compensation model to determine the corrosion charge compensation amount output by the compensation model, wherein the compensation model is pre-trained based on experimental data of multiple batteries at different temperatures.

[0081] Optionally, the evaluation module 603 is specifically used to determine whether the corrosion charge exceeds a threshold; if so, it is determined that the target battery has casing corrosion; if not, it is determined that the risk of the target battery having casing corrosion is low.

[0082] Optionally, when the risk of casing corrosion of the target battery is low, the evaluation module 603 is specifically used to evaluate the corrosion state of the target battery according to a preset period, wherein the preset period is negatively correlated with the most recent corrosion charge of the target battery.

[0083] Optionally, when the risk of casing corrosion of the target battery is low, the evaluation module 603 is specifically used to evaluate the corrosion status of the target battery again after determining a first preset time interval when the corrosion charge is within a first preset range; and to evaluate the corrosion status of the target battery again after determining a second preset time interval when the corrosion charge is within a second preset range, wherein the maximum value of the first preset range is not greater than the minimum value of the second preset range, and the first preset time interval is greater than the second preset time interval.

[0084] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for apparatus or device embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The professional and apparatus embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0085] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of the relevant data must comply with the relevant laws, regulations and standards of the relevant countries and regions, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0086] This application also provides a computer storage medium for storing a computer program that, when executed by a processor, implements the steps of any one of the methods described in the foregoing method embodiments.

[0087] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the method described in any of the foregoing method embodiments.

[0088] This application also provides a battery corrosion status assessment device, including a processor and a memory, wherein the memory is used to store a computer program product, which, when executed by the processor, implements the steps of any one of the methods described in the foregoing method embodiments.

[0089] in, Figure 7 An exemplary architecture of a battery corrosion state assessment device is shown, which is used to perform the battery corrosion state assessment method described above. Specifically, it may include a processor 710, a video display adapter 711, a disk drive 712, an input / output interface 713, a network interface 714, and a memory 720. The processor 710, video display adapter 711, disk drive 712, input / output interface 713, network interface 714, and memory 720 can communicate with each other via a communication bus 730.

[0090] The processor 710 can be implemented using a general-purpose CPU, microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits to execute relevant programs and implement the technical solution provided in this application.

[0091] The memory 720 can be implemented in the form of ROM (Read Only Memory), RAM (Random Access Memory), static storage device, dynamic storage device, etc. The memory 720 can store the operating system 721 for controlling the operation of the electronic device 700, and the basic input / output system (BIOS) 722 for controlling the low-level operations of the electronic device 700. Additionally, it can store a web browser 723, a data storage management system 724, and a media file playback device 800, etc. The aforementioned media file playback device 800 can be the application program that specifically implements the aforementioned steps in this embodiment. In summary, when the technical solution provided in this application is implemented through software or firmware, the relevant program code is stored in the memory 720 and is called and executed by the processor 710.

[0092] Input / output interface 713 is used to connect input / output modules to realize information input and output. Input / output modules can be configured as components in the device (not shown in the figure) or externally connected to the device to provide corresponding functions. Input devices may include keyboards, mice, touch screens, microphones, various sensors, etc., and output devices may include displays, speakers, vibrators, indicator lights, etc.

[0093] Network interface 714 is used to connect a communication module (not shown in the figure) to enable communication between this device and other devices. The communication module can communicate via wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0094] Bus 730 includes a pathway for transmitting information between various components of the device, such as processor 710, video display adapter 711, disk drive 712, input / output interface 713, network interface 714, and memory 720.

[0095] It should be noted that although the above-described device only shows the processor 710, video display adapter 711, disk drive 712, input / output interface 713, network interface 714, memory 720, bus 730, etc., in specific implementations, the device may also include other components necessary for normal operation. Furthermore, those skilled in the art will understand that the above-described device may only include the components necessary for implementing the solution of this application, and does not necessarily include all the components shown in the figures.

[0096] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a computer program product. This computer program product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0097] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A battery management system, characterized in that, The battery management system is configured to perform the following steps: A control first circuit connects the negative terminal of the target battery and the casing of the target battery, and monitors a first voltage between the negative terminal and the casing. The first circuit includes at least a first resistor. When the first voltage drops to a preset value, the control second circuit connects the positive terminal of the target battery and the casing. The second circuit includes at least a second resistor. Determine the first charge transfer amount flowing through the first resistor during the period when the first voltage drops from the initial voltage value to the preset value, and determine the second charge transfer amount flowing through the second resistor during the period when the first voltage recovers from the preset value to the initial voltage value before connecting the first resistor; The corrosion charge of the target battery is determined based on the first charge transfer amount and the second charge transfer amount. The corrosion charge is used to assess whether the target battery has experienced casing corrosion.

2. The battery management system as described in claim 1, characterized in that, Before the step of connecting the first control circuit to the negative terminal of the target battery and the casing of the target battery, the battery management system is further configured to: Based on the initial state parameters of the target battery, the resistance values ​​of the first resistor and the second resistor are determined, wherein the initial state parameters include the open-circuit voltage of the target battery and the initial voltage value before the negative terminal is connected to the first circuit.

3. The battery management system as described in claim 1, characterized in that, The step of determining the amount of first charge transfer flowing through the first resistor during the period when the first voltage drops from the initial voltage value to the preset value includes: Determine the current flowing through the first resistor during the period when the first voltage drops from the initial voltage value to the preset value; The first charge transfer amount flowing through the first resistor is determined based on the integration of the current flowing through the first resistor and the time.

4. The battery management system as described in claim 1, characterized in that, The step of determining the amount of second charge transfer flowing through the second resistor during the period when the first voltage recovers from the preset value to the initial voltage value before connecting the first resistor specifically includes: Determine the current flowing through the second resistor during the period when the first voltage recovers from the preset value to the initial voltage value before the first resistor is connected; The second charge transfer amount flowing through the second resistor is determined based on the integration of the current and time flowing through the second resistor.

5. The battery management system as described in claim 1, characterized in that, The step of determining the corrosion charge of the target battery based on the first charge transfer amount and the second charge transfer amount specifically includes: Monitor the temperature of the target battery; Based on the stated temperature, determine the amount of corrosion charge compensation; The corrosion charge of the target battery is determined based on the corrosion charge compensation amount, the first charge transfer amount, and the second charge transfer amount.

6. The battery management system as described in claim 5, characterized in that, The step of determining the corrosion charge compensation amount based on the temperature specifically includes: The corrosion charge compensation amount is determined based on the temperature and a preset compensation function, wherein the compensation function is obtained in advance by fitting experimental data of multiple batteries at different temperatures.

7. The battery management system as described in claim 5, characterized in that, The step of determining the corrosion charge compensation amount based on the temperature specifically includes: The temperature and target temperature are input into a pre-trained compensation model to determine the corrosion charge compensation amount output by the compensation model. The compensation model is pre-trained based on experimental data from multiple batteries at different temperatures.

8. The battery management system as described in claim 1, characterized in that, The battery management system is also configured to: Determine whether the corrosion charge exceeds a threshold. If so, then it is determined that the target battery has casing corrosion. If not, then the risk of casing corrosion in the target battery is determined to be low.

9. The battery management system as described in claim 8, characterized in that, When the risk of casing corrosion in the target battery is low, the battery management system is also configured to: The corrosion state of the target battery is evaluated according to a preset period, wherein the preset period is negatively correlated with the most recent corrosion charge of the target battery.

10. The battery management system as described in claim 8, characterized in that, When the risk of casing corrosion in the target battery is low, the battery management system is also configured to: When the corrosion charge is within the first preset range, the target battery is evaluated for corrosion status again after a first preset time interval is determined. When the corrosion charge is within the second preset range, the corrosion status of the target battery is evaluated again at a second preset time interval, wherein the maximum value of the first preset range is not greater than the minimum value of the second preset range, and the first preset time is greater than the second preset time.

11. A method for assessing the corrosion state of a battery, characterized in that, include: A first circuit is connected to the negative terminal of the target battery and the casing of the target battery to monitor a first voltage between the negative terminal and the casing. The first circuit includes at least a first resistor. When the first voltage drops to a preset value, the second circuit is connected to the positive terminal of the target battery and the casing, the second circuit including at least a second resistor; The first charge transfer amount flowing through the first resistor when the first voltage drops to a preset value, and the second charge transfer amount flowing through the second resistor when the first voltage recovers to the initial voltage value before connecting the first circuit; The corrosion charge of the target battery is determined based on the first charge transfer amount and the second charge transfer amount. The corrosion charge is used to assess whether the target battery has experienced casing corrosion.

12. A method for assessing the corrosion state of a battery pack, characterized in that, include: Each battery in the battery pack is taken as a target battery, and its corresponding corrosion charge is determined. The maximum value among the corrosion charges is taken as the corrosion charge of the battery pack; The corrosion status of the battery pack is assessed based on the corrosion charge of the battery pack. The corrosion charge corresponding to each of the batteries is obtained using the following method: A first circuit is connected to the negative terminal of the target battery and the casing of the battery pack, and the impedance between the batteries other than the target battery and the casing is not less than a threshold. A first voltage between the negative terminal and the casing is monitored. The first circuit includes at least a first resistor. When the first voltage reaches a preset value, the second circuit is connected to the positive terminal of the target battery and the casing, and the second circuit includes at least a second resistor; The first charge transfer amount flowing through the first resistor when the first voltage drops to a preset value, and the second charge transfer amount flowing through the second resistor when the first voltage recovers to the initial voltage value before connecting the first circuit; The corrosion charge of the battery pack is determined based on the difference between the first charge transfer amount and the second charge transfer amount, and the corrosion charge is used to assess the corrosion status of the battery pack.

13. A method for evaluating the corrosion state of a battery pack, characterized in that, include: Each battery in the battery pack is taken as a target battery, and its corresponding corrosion charge is determined. The maximum value among the corrosion charges is taken as the corrosion charge of the battery pack; The corrosion status of the battery pack is assessed based on the corrosion charge of the battery pack. The corrosion charge corresponding to each of the batteries is obtained using the following method: A first circuit is connected to the negative terminal of the target battery and the casing of the battery pack, and the impedance between the batteries other than the target battery and the casing is not less than a threshold. A first voltage between the negative terminal and the casing is monitored. The first circuit includes at least a first resistor. When the first voltage reaches a preset value, the second circuit is connected to the positive terminal of the target battery and the casing, and the second circuit includes at least a second resistor; The first charge transfer amount flowing through the first resistor when the first voltage drops to a preset value, and the second charge transfer amount flowing through the second resistor when the first voltage recovers to the initial voltage value before connecting the first circuit; The corrosion charge of the battery pack is determined based on the difference between the first charge transfer amount and the second charge transfer amount, and the corrosion charge is used to assess the corrosion status of the battery pack.

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