Internal short-circuit current online detection method and device and battery management system
By acquiring the battery's state of charge and calculating leakage current, the high energy consumption and poor adaptability of existing technologies for internal short-circuit current detection are solved, enabling low-energy online detection of battery internal short-circuit current and improving early warning capabilities.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU QINGTAO NEW ENERGY TECH CO LTD
- Filing Date
- 2025-12-10
- Publication Date
- 2026-04-10
AI Technical Summary
Existing technologies struggle to effectively identify weak fault currents caused by high-resistance internal short circuits, resulting in insufficient early warning capabilities. Furthermore, detection methods based on complete charge-discharge cycles cannot adapt to the partial charge-discharge conditions commonly encountered in practical applications, increasing system energy consumption and control complexity.
By acquiring the initial and final states of charge during the charging and discharging processes of the battery, the leakage current of a complete charge-discharge cycle is calculated. The internal short-circuit current value is calculated using a formula, and the battery's equivalent internal short-circuit resistance is then used for detection.
It achieves low-energy-consumption online detection of internal short-circuit current in batteries, has strong adaptability, can identify internal short-circuit current at an early stage, and improves safety early warning capabilities.
Smart Images
Figure CN121831233A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of internal short circuit current detection, in particular to an internal short circuit current online detection method, device and battery management system. BACKGROUND
[0002] Internal short circuit may be caused by local failure of the separator, lithium crystallization and other problems in the battery. Internal short circuit is usually a gradual deterioration process, which may cause local temperature rise and capacity decay, and may evolve into thermal runaway in severe cases, leading to fire, explosion and other safety accidents.
[0003] The current internal short circuit detection method cannot effectively identify the weak fault current caused by high resistance internal short circuit, resulting in insufficient early warning capability. The detection method based on complete charge and discharge cycles cannot adapt to the common partial charge and discharge conditions in actual application, and it needs to rely on specific test conditions to obtain complete data, which not only increases the system energy consumption and control complexity, but also limits its application in actual scenarios. SUMMARY
[0004] The technical problem to be solved by the embodiments of the present application is to provide an internal short circuit current online detection method, device and battery management system. The battery is charged and discharged respectively to obtain the initial state of charge and the terminal state of charge of the battery under charging and discharging, and then the leakage current of the complete charge and discharge cycle is calculated. The leakage current value, i.e. the internal short circuit current value, can be used for battery internal short circuit current detection, has low energy consumption and strong adaptability.
[0005] To solve the above technical problems, the present application provides an internal short circuit current online detection method, comprising, obtaining the initial state of charge and the terminal state of charge of the battery in the charge capacity calculation interval, and the initial state of charge and the terminal state of charge of the battery in the discharge capacity calculation interval; calculating the actual total charge capacity of the complete charging process based on the actual inflow capacity of the charge capacity calculation interval, and calculating the actual total discharge capacity of the complete discharge process based on the actual outflow capacity of the discharge capacity calculation interval; calculating the leakage current of one complete charge and discharge cycle according to the actual total charge capacity and the actual total discharge capacity; obtaining the internal short circuit current corresponding to one complete charge and discharge cycle according to the leakage current of one complete charge and discharge cycle and the total duration.
[0006] In a feasible implementation manner, the initial state of charge and the terminal state of charge of the battery in the charge capacity calculation interval, and the initial state of charge and the terminal state of charge of the battery in the discharge capacity calculation interval are obtained, comprising, A charging static stage is arranged before and after the charging capacity calculation interval respectively, and the end voltage of the battery in the charging static stage is measured to obtain the pre-charging end voltage and the post-charging end voltage, the initial state of charge of the battery in the charging capacity calculation interval is obtained by querying the preset reference table according to the pre-charging end voltage, and the terminal state of charge of the battery in the charging capacity calculation interval is obtained by querying the reference table according to the post-charging end voltage; A discharging static stage is arranged before and after the discharging capacity calculation interval respectively, and the end voltage of the battery in the discharging static stage is measured to obtain the pre-discharging end voltage and the post-discharging end voltage, the initial state of charge of the battery in the discharging capacity calculation interval is obtained by querying the reference table according to the pre-discharging end voltage, and the terminal state of charge of the battery in the discharging capacity calculation interval is obtained by querying the reference table according to the post-discharging end voltage; The reference table is a reference table of the relationship between the end voltage and the state of charge of the battery.
[0007] In a feasible implementation, the difference between the terminal state of charge and the initial state of charge of the charging capacity calculation interval is greater than or equal to 20% and less than or equal to 70%; The difference between the terminal state of charge and the initial state of charge of the discharging capacity calculation interval is greater than or equal to 20% and less than or equal to 70%.
[0008] In a feasible implementation, in the step of calculating the actual total charging capacity of the complete charging process based on the actual inflow capacity of the charging capacity calculation interval, the actual total charging capacity of the complete charging process is calculated by the following formula, ; Wherein, represents the actual total charging capacity of the complete charging process; represents the actual inflow capacity of the charging capacity calculation interval; represents the initial state of charge of the charging capacity calculation interval; represents the terminal state of charge of the charging capacity calculation interval; represents the time corresponding to the initial state of charge of the charging capacity calculation interval; represents the time corresponding to the terminal state of charge of the charging capacity calculation interval; represents the current at the time t collected in the charging capacity calculation interval.
[0009] In one feasible implementation, in the step of calculating the actual total discharge capacity of the complete discharge process based on the actual outflow capacity of the discharge capacity calculation interval, the actual total discharge capacity of the complete discharge process is calculated using the following formula. ; in, The actual total discharge capacity represents the complete discharge process; This represents the actual outflow capacity within the discharge capacity calculation range; This indicates the initial state of charge within the discharge capacity calculation range; This indicates the final state of charge within the discharge capacity calculation range; This indicates the time corresponding to the initial state of charge within the discharge capacity calculation interval; This indicates the time corresponding to the termination of the charging state within the discharge capacity calculation interval; This represents the current collected at time t within the discharge capacity calculation interval.
[0010] In one feasible implementation, the leakage current of a complete charge-discharge cycle is calculated using the following formula. ; in, This represents the leakage current during one complete charge-discharge cycle; The actual total charging capacity represents the complete charging process; This represents the preset coulomb efficiency; The actual total discharge capacity represents the complete discharge process.
[0011] In one feasible implementation, the internal short-circuit current corresponding to a complete charge-discharge cycle is calculated using the following formula. ; in, This represents the internal short-circuit current corresponding to one complete charge-discharge cycle; This represents the leakage current during one complete charge-discharge cycle; This indicates the total duration of a complete charge-discharge cycle.
[0012] In one feasible implementation, after obtaining the internal short-circuit current corresponding to a complete charge-discharge cycle based on the leakage current and total duration of a complete charge-discharge cycle, the online detection method for the internal short-circuit current further includes... The equivalent internal short-circuit resistance of the battery is obtained by dividing the average terminal voltage of a complete charge-discharge cycle by the internal short-circuit current of the same complete charge-discharge cycle. The equivalent internal short-circuit resistance is then compared with a set threshold to obtain the short-circuit evolution stage of the battery.
[0013] Accordingly, this application also relates to an online short-circuit current detection device, comprising, The state of charge acquisition unit is configured to acquire the initial state of charge and the final state of charge of the battery during the charging capacity calculation period, as well as the initial state of charge and the final state of charge of the battery during the discharging capacity calculation period. The capacity calculation unit is configured to calculate the actual total charging capacity of the complete charging process based on the actual inflow capacity of the charging capacity calculation interval, and to calculate the actual total discharging capacity of the complete discharging process based on the actual outflow capacity of the discharging capacity calculation interval. The leakage power calculation unit is configured to calculate the leakage power of a complete charge-discharge cycle based on the actual total charging capacity and the actual total discharging capacity. The internal short-circuit current acquisition unit is configured to obtain the internal short-circuit current corresponding to a complete charge-discharge cycle based on the leakage current and total duration of a complete charge-discharge cycle. Accordingly, this application also relates to a battery management system, including the aforementioned online short-circuit current detection device.
[0014] Implementing this invention has the following beneficial effects: The battery is charged and discharged separately to obtain the initial state of charge and the final state of charge under the charge and discharge conditions. Then, the leakage current of a complete charge and discharge cycle is calculated. The leakage current value, i.e. the internal short circuit current value, is calculated based on the leakage current value. It can be used for internal short circuit detection of batteries. It has low energy consumption and strong adaptability.
[0015] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description
[0016] Figure 1 This is a flowchart illustrating the steps of the online detection method for internal short-circuit current of the present invention; Figure 2 This is a schematic diagram of step S100 of the present invention; Figure 3 This is a schematic diagram of the present invention including step S500; Figure 4This is a schematic diagram of the online detection device for internal short-circuit current of the present invention. Detailed Implementation
[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0018] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.
[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0020] Lithium-ion batteries, as the mainstream electrochemical energy storage medium, are prone to problems such as localized separator failure and lithium metal crystallization under the influence of manufacturing defects, mechanical abuse, or long-term cycle aging, leading to internal short circuits. These internal short circuits often exhibit a progressive deterioration trend, causing localized temperature rises and capacity decay within the battery. In severe cases, they can evolve into thermal runaway, triggering fires, explosions, and other safety accidents. Therefore, developing technologies that can be integrated into a Battery Management System (BMS) and monitor internal short-circuit current in real time is of great significance for early warning and proactive protection of battery safety. Current detection methods have significant shortcomings. On the one hand, they struggle to effectively identify the weak fault current caused by high-resistance internal short circuits, resulting in insufficient early warning capabilities. On the other hand, detection methods based on complete charge-discharge cycles cannot adapt to the partial charge-discharge conditions commonly encountered in practical applications and require specific test conditions to obtain complete data, increasing system energy consumption and control complexity, and limiting their application in real-world scenarios.
[0021] This application provides a method for online detection of internal short-circuit current, referring to... Figure 1 ,include, Step S100: Obtain the starting state of charge and the ending state of charge of the battery's charging capacity calculation range, as well as the starting state of charge and the ending state of charge of the discharging capacity calculation range. Step S200: Calculate the actual total charging capacity of the complete charging process based on the actual inflow capacity of the charging capacity calculation interval, and calculate the actual total discharging capacity of the complete discharging process based on the actual outflow capacity of the discharging capacity calculation interval. Step S300: Calculate the leakage power of a complete charge-discharge cycle based on the actual total charging capacity and the actual total discharging capacity. Step S400: Obtain the internal short-circuit current corresponding to a complete charge-discharge cycle based on the leakage current and total duration of a complete charge-discharge cycle.
[0022] In one feasible implementation, step S100 involves obtaining the initial and final states of charge (SOC) of the battery's charging capacity calculation interval, as well as the initial and final SOC of the discharging capacity calculation interval, referring to... Figure 2 ,include, Step S101: Set a charging resting stage before and after the charging capacity calculation interval, measure the battery terminal voltage during the charging resting stage to obtain the charging front voltage and charging back voltage, and obtain the battery's initial state of charge in the charging capacity calculation interval by looking up a preset lookup table based on the charging front voltage, and obtain the battery's final state of charge in the charging capacity calculation interval by looking up a lookup table based on the charging back voltage. Step S102: Set a discharge resting stage before and after the discharge capacity calculation interval, measure the terminal voltage of the battery in the discharge resting stage to obtain the discharge front voltage and discharge back voltage, look up the reference table according to the discharge front voltage to obtain the battery's initial state of charge in the discharge capacity calculation interval, and look up the reference table according to the discharge back voltage to obtain the battery's final state of charge in the discharge capacity calculation interval. The comparison table is a comparison table of the relationship between terminal voltage and battery state of charge.
[0023] For example, the process of obtaining the state of charge at the boundary of the battery charging and discharging capacity calculation interval is achieved by setting four specific resting phases and measuring the terminal voltage during a complete charge-discharge cycle.
[0024] In this process, before the battery begins charging (during the pre-charging resting phase), the stable battery terminal voltage at the end of this resting phase is measured and recorded as the charging front-end voltage. This voltage is then used to consult a voltage-state-of-charge (SOC) lookup table to obtain the initial SOC for the charging capacity calculation interval. After charging within the set charging capacity calculation interval ends (during the post-charging resting phase), the stable terminal voltage is measured and recorded as the charging back-end voltage. This voltage is then used to consult a lookup table to obtain the final SOC for the charging capacity calculation interval. Through these two resting measurements and table lookups, the SOC variation range corresponding to the charging capacity calculation interval is determined.
[0025] Similarly, for the discharge capacity calculation interval, before the start of discharge, i.e. during the pre-discharge resting stage, the voltage at the discharge front end is measured, and the initial state of charge of the discharge capacity calculation interval is obtained by looking up the table; after the discharge ends in the set discharge capacity calculation interval, i.e. during the post-discharge resting stage, the voltage at the discharge back end is measured, and the final state of charge of the discharge capacity calculation interval is obtained by looking up the table.
[0026] For example, in step S101, the difference between the ending state of charge and the starting state of charge in the charging capacity calculation interval is greater than or equal to 20% and less than or equal to 70%. Specifically, the process of charging the battery from a lower state of charge (SOC) to a higher SOC is defined as a continuous interval within which the charging capacity is calculated. Before charging begins, a first resting period is performed, and the initial SOC of this calculation interval is determined by consulting the terminal voltage-SOC table, resulting in SOC1 = 20%. After charging ends, a second resting period is performed, and the final SOC of this calculation interval is determined by consulting the table again, resulting in SOC2 = 70%. At this point, the change in SOC within this calculation interval (ΔSOC = SOC2 - SOC1) is 50%.
[0027] If ΔSOC is too small (e.g., less than 20%), the calibration window used for capacity estimation is too narrow. In this case, small errors in current integration or small deviations in SOC boundary values caused by terminal voltage measurement and table lookup will be amplified when calculating the actual total charging capacity, leading to a decrease in the accuracy of the internal short-circuit current calculation. If ΔSOC is too large (e.g., exceeding 70%), although a larger data base helps improve the statistical stability of a single capacity calibration calculation, the charging time required to complete one calibration will be correspondingly extended. This contradicts the online diagnostic requirement of rapid and frequent monitoring of internal short-circuit faults, hindering efficient real-time safety monitoring. Therefore, this application sets the ΔSOC of the charging capacity calculation range within this range, ensuring the accuracy of internal short-circuit current calculation while guaranteeing real-time monitoring efficiency.
[0028] The selection principle for the discharge capacity calculation interval is the same as that for setting it. Its ΔSOC is also preferably controlled within the same range (20%-70%). The specific SOC start and end points of the two calculation intervals corresponding to charging and discharging can be the same, or they can be set differently according to the actual working conditions and strategy requirements. This will not be elaborated here.
[0029] In one feasible implementation, in step S200, where the actual total charging capacity of the complete charging process is calculated based on the actual inflow capacity within the charging capacity calculation interval, the actual total charging capacity of the complete charging process is obtained using the following formula. ; Among them, Q C This represents the actual total charging capacity during the complete charging process; Q1 represents the actual inflow capacity within the charging capacity calculation range; x1 represents the initial state of charge within the charging capacity calculation range; x2 represents the final state of charge within the charging capacity calculation range; t1 represents the moment corresponding to the initial state of charge within the charging capacity calculation interval; t2 represents the time corresponding to the termination of the charging state within the charging capacity calculation interval; I1(t) represents the current collected at time t within the charging capacity calculation interval.
[0030] For example, the initial state of charge of the charging capacity calculation range in step S200 can be... The termination state of charge within the charging capacity calculation range can be The charging capacity calculation range can be to ,so This indicates that the battery is in to The actual inflow capacity of the interval.
[0031] It can be understood that the complete charging process in the formula refers to the entire charging range of the battery from 0% SOC to 100% SOC.
[0032] In one feasible implementation, in step S200, where the actual total discharge capacity of the complete discharge process is calculated based on the actual outflow capacity within the discharge capacity calculation range, the actual total charging capacity of the complete discharge process is calculated using the following formula. ; Among them, Q D This represents the actual total discharge capacity during the complete discharge process; Q2 represents the actual outflow capacity within the discharge capacity calculation range; y1 represents the initial state of charge within the discharge capacity calculation range; y2 represents the final state of charge within the discharge capacity calculation interval; t3 represents the moment corresponding to the initial state of charge within the discharge capacity calculation interval; t4 represents the time corresponding to the termination of the charging state within the discharge capacity calculation interval; I2(t) represents the current collected at time t within the discharge capacity calculation interval.
[0033] For example, the initial state of charge of the discharge capacity calculation interval in step S200 can be... The termination state of charge within the discharge capacity calculation range can be The discharge capacity calculation range can be to ,so This indicates that the battery is in to The actual outflow capacity of the interval.
[0034] It is understandable that the calculation of the actual total discharge capacity of the complete discharge process is also based on the discharge capacity calculation range, using the same proportional extrapolation principle, extending the local measurement value to the complete discharge process from 100% SOC to 0% SOC.
[0035] In one feasible implementation, in step S300, the leakage current of a complete charge-discharge cycle is calculated using the following formula. ; in, This represents the leakage current during a complete charge-discharge cycle. This represents the actual total charging capacity during the complete charging process; The preset coulomb efficiency is derived from the calibration data when the battery leaves the factory. This represents the actual total discharge capacity during the complete discharge process.
[0036] In one feasible implementation, in step S400, the internal short-circuit current of a complete charge-discharge cycle is calculated using the following formula. ; in, This represents the internal short-circuit current of a complete charge-discharge cycle. This represents the leakage current during a complete charge-discharge cycle. This indicates the total duration of a complete charge-discharge cycle.
[0037] In one feasible implementation, after obtaining the internal short-circuit current corresponding to a complete charge-discharge cycle based on the leakage current and total duration of a complete charge-discharge cycle in step S400, refer to... Figure 3 The online detection method for internal short-circuit current also includes, Step S500: Divide the average terminal voltage of a complete charge-discharge cycle by the internal short-circuit current of a complete charge-discharge cycle to obtain the equivalent internal short-circuit resistance of the battery. Then, the equivalent internal short-circuit resistance value The short-circuit evolution stage of the battery is obtained by comparing it with a set threshold.
[0038] For example, for ternary lithium batteries, the short-circuit evolution stages include an early micro-short-circuit stage and a mild short-circuit stage. The threshold value can be set as follows: When the equivalent internal short-circuit resistance value Greater than or equal to When the battery is determined to be in the early micro-short circuit stage, the equivalent internal short circuit resistance value is... Less than At that time, the battery was determined to be in a minor short circuit stage.
[0039] Accordingly, this application also relates to an online detection device for internal short-circuit current, referring to... Figure 4 ,include, The state of charge acquisition unit 10 is configured to acquire the starting state of charge and the ending state of charge of the battery in the charging capacity calculation interval, as well as the starting state of charge and the ending state of charge of the discharging capacity calculation interval. The capacity calculation unit 20 is configured to calculate the actual total charging capacity of the complete charging process based on the actual inflow capacity of the charging capacity calculation interval, and to calculate the actual total discharging capacity of the complete discharging process based on the actual outflow capacity of the discharging capacity calculation interval. The leakage power calculation unit 30 is configured to calculate the leakage power of a complete charge-discharge cycle based on the actual total charging capacity and the actual total discharging capacity. The internal short-circuit current acquisition unit 40 is configured to obtain the internal short-circuit current corresponding to a complete charge-discharge cycle based on the leakage current and total duration of a complete charge-discharge cycle.
[0040] For example, before charging the battery, it is placed for the first time and the terminal voltage is measured. After charging is completed, the battery is placed for the second time and the terminal voltage is measured again. The state of charge acquisition unit 10 will substitute the measured terminal voltages into a lookup table. The lookup table can be a lookup table of the relationship between terminal voltage and battery state of charge. By directly substituting the measured terminal voltage into the lookup table, the corresponding state of charge can be found, thereby obtaining the state of charge at different placement stages. The same applies to the discharge process.
[0041] The capacity calculation unit 20 calculates the actual total charging capacity of the complete charging process based on the actual inflow capacity of the charging capacity calculation interval, and calculates the actual total discharging capacity of the complete discharging process based on the actual outflow capacity of the discharging capacity calculation interval. The leakage power calculation unit 30 multiplies the actual total charging capacity of the complete charging process by the coulomb efficiency and then subtracts the actual total discharging capacity of the complete discharging process to obtain the leakage power of a complete charge-discharge cycle. The internal short-circuit current acquisition unit 40 obtains the internal short-circuit current value corresponding to a complete charge-discharge cycle by dividing the leakage current of a complete charge-discharge cycle by the total duration. In the lithium battery internal short-circuit current online detection device, the state of charge acquisition unit 10, the used capacity calculation unit 20, the leakage current calculation unit 30, and the internal short-circuit current acquisition unit 40 work together to achieve accurate detection of early internal short circuits in the battery. This application can be used for battery internal short-circuit detection, with low energy consumption and strong adaptability.
[0042] The core function of the State of Charge (SOC) acquisition unit 10 is to provide accurate SOC boundary data for subsequent capacity calculation and internal short-circuit current detection. Its working logic closely relies on the OCV-SOC lookup table (i.e., the open-circuit voltage-state of charge correspondence table). When the battery enters the resting stage before charging, the unit collects the battery's resting terminal voltage (at this time, there is no current flowing in the battery, and the terminal voltage is the open-circuit voltage OCV that truly reflects the internal chemical state), and looks up the corresponding SOC value based on the preset OCV-SOC lookup table. This is the initial state of charge of the charging process. After charging is completed, the battery enters the resting stage again to eliminate polarization effects. The unit collects the resting terminal voltage again and completes the table lookup operation to obtain the final state of charge of the charging process. Similarly, in the resting stages before and after discharge, the unit obtains the initial and final states of charge of the discharge process through the same process.
[0043] The capacity calculation unit 20 calculates the actual charging capacity within the SOC range determined by the state of charge acquisition unit 10 using the ampere-hour integration method: During the charging capacity calculation range (i.e., from the start of charging to the end of charging), the unit collects the load current in real time during the charging process, integrates the current over the corresponding time dimension in that range, and obtains the actual inflow capacity of the charging capacity calculation range. Within the discharge capacity calculation interval (i.e., from the initial state of charge to the final state of charge), the cell collects the discharge current and performs integration using the same method to obtain the actual outflow capacity within the discharge capacity calculation interval. The capacity calculation unit 20 derives the actual total charge / discharge capacity of the complete charge / discharge process based on the interval capacity: This unit expands the interval capacity to the capacity of the complete charge / discharge process through a proportional conversion formula.
[0044] The leakage calculation unit 30 takes into account the coulombic efficiency (the ratio of battery discharge capacity to charge capacity, calibrated at the factory, typically ≥99%). When an internal short circuit exists in the battery, some charge will be lost through the internal short circuit path (i.e., leakage), causing the actual discharge capacity to be less than the ideal value. Therefore, the leakage... .
[0045] The internal short-circuit current acquisition unit 40 first acquires the total duration of a complete charge-discharge cycle, and then uses the formula... Calculate the average internal short-circuit current.
[0046] Accordingly, this application also relates to a battery management system, including the aforementioned online short-circuit current detection device.
[0047] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0048] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A method for online detection of internal short-circuit current, characterized in that, include, Obtain the starting and ending states of charge for the battery's charging capacity calculation range, as well as the starting and ending states of charge for the discharging capacity calculation range. The actual total charging capacity of the complete charging process is calculated based on the actual inflow capacity of the charging capacity calculation interval, and the actual total discharging capacity of the complete discharging process is calculated based on the actual outflow capacity of the discharging capacity calculation interval. Calculate the leakage power of a complete charge-discharge cycle based on the actual total charging capacity and the actual total discharging capacity; The internal short-circuit current corresponding to a complete charge-discharge cycle is obtained based on the leakage current and total duration of a complete charge-discharge cycle.
2. The online detection method for internal short-circuit current according to claim 1, characterized in that, The acquisition of the initial and final states of charge (SOC) of the battery's charging capacity calculation range, and the initial and final SOC of the discharging capacity calculation range, includes: A charging resting stage is set before and after the charging capacity calculation interval. The terminal voltage of the battery in the charging resting stage is measured to obtain the charging front voltage and the charging back voltage. The charging front voltage is used to look up a preset lookup table to obtain the battery's initial state of charge in the charging capacity calculation interval. The charging back voltage is used to look up the lookup table to obtain the battery's final state of charge in the charging capacity calculation interval. A discharge resting stage is set before and after the discharge capacity calculation interval. The terminal voltage of the battery in the discharge resting stage is measured to obtain the discharge front voltage and discharge back voltage. The battery's initial state of charge in the discharge capacity calculation interval is obtained by looking up the reference table based on the discharge front voltage. The battery's final state of charge in the discharge capacity calculation interval is obtained by looking up the reference table based on the discharge back voltage. The reference table is a table showing the relationship between terminal voltage and battery state of charge.
3. The online detection method for internal short-circuit current according to claim 2, characterized in that, The difference between the termination state of charge and the starting state of charge within the charging capacity calculation range is greater than or equal to 20% and less than or equal to 70%. The difference between the termination state of charge and the starting state of charge in the discharge capacity calculation interval is greater than or equal to 20% and less than or equal to 70%.
4. The online detection method for internal short-circuit current according to claim 1, characterized in that, In the step of calculating the actual total charging capacity of the complete charging process based on the actual inflow capacity within the charging capacity calculation range, the actual total charging capacity of the complete charging process is calculated using the following formula. ； in, The actual total charging capacity represents the complete charging process; This represents the actual inflow capacity within the charging capacity calculation range; This indicates the initial state of charge within the charging capacity calculation range; This indicates the final state of charge within the charging capacity calculation range; This indicates the time corresponding to the initial state of charge within the charging capacity calculation interval; This indicates the time corresponding to the termination of the charging state within the charging capacity calculation interval; This represents the current collected at time t within the charging capacity calculation interval.
5. The online detection method for internal short-circuit current according to claim 1, characterized in that, In the step of calculating the actual total discharge capacity of the complete discharge process based on the actual outflow capacity of the discharge capacity calculation range, the actual total discharge capacity of the complete discharge process is calculated using the following formula. ； in, The actual total discharge capacity represents the complete discharge process; This represents the actual outflow capacity within the discharge capacity calculation range; This indicates the initial state of charge within the discharge capacity calculation range; This indicates the final state of charge within the discharge capacity calculation range; This indicates the time corresponding to the initial state of charge within the discharge capacity calculation interval; This indicates the time corresponding to the termination of the charging state within the discharge capacity calculation interval; This represents the current collected at time t within the discharge capacity calculation interval.
6. The online detection method for internal short-circuit current according to claim 1, characterized in that, The leakage current of a complete charge-discharge cycle is calculated using the following formula. ； in, This represents the leakage current during one complete charge-discharge cycle; The actual total charging capacity represents the complete charging process; This represents the preset coulomb efficiency; The actual total discharge capacity represents the complete discharge process.
7. The online detection method for internal short-circuit current according to claim 1, characterized in that, The internal short-circuit current corresponding to a complete charge-discharge cycle is calculated using the following formula. ； in, This represents the internal short-circuit current corresponding to one complete charge-discharge cycle; This represents the leakage current during one complete charge-discharge cycle; This indicates the total duration of a complete charge-discharge cycle.
8. The online detection method for internal short-circuit current according to claim 1, characterized in that, After obtaining the internal short-circuit current corresponding to a complete charge-discharge cycle based on the leakage current and total duration of a complete charge-discharge cycle, the online detection method for internal short-circuit current further includes... The equivalent internal short-circuit resistance of the battery is obtained by dividing the average terminal voltage of a complete charge-discharge cycle by the internal short-circuit current of the same complete charge-discharge cycle. The equivalent internal short-circuit resistance is then compared with a set threshold to obtain the short-circuit evolution stage of the battery.
9. An online short-circuit current detection device, characterized in that, include, The state of charge acquisition unit is configured to acquire the initial state of charge and the final state of charge of the battery during the charging capacity calculation period, as well as the initial state of charge and the final state of charge of the battery during the discharging capacity calculation period. The capacity calculation unit is configured to calculate the actual total charging capacity of the complete charging process based on the actual inflow capacity of the charging capacity calculation interval, and to calculate the actual total discharging capacity of the complete discharging process based on the actual outflow capacity of the discharging capacity calculation interval. The leakage power calculation unit is configured to calculate the leakage power of a complete charge-discharge cycle based on the actual total charging capacity and the actual total discharging capacity. The internal short-circuit current acquisition unit is configured to obtain the internal short-circuit current corresponding to a complete charge-discharge cycle based on the leakage current and total duration of a complete charge-discharge cycle.
10. A battery management system, characterized in that, Includes the online short-circuit current detection device as described in claim 9.