A lithium iron phosphate graphite battery charging and discharging protection method and system based on phase transition mutation point identification

Abstract

This invention provides a method and system for charging and discharging protection of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification, relating to the field of lithium-ion battery management technology. First, the historical comprehensive state of harmonics (SOH), real-time voltage, real-time current, and charge transfer resistance of the target battery are obtained. Key-value matching is performed using the historical comprehensive SOH to obtain dynamic charging and discharging parameters suitable for the current state of the battery. Then, after first-order low-pass filtering, the real-time voltage is combined with the real-time current and the sliding window length to perform feature calculations to obtain basic charging and discharging characteristics. Subsequently, based on the relationship between the smoothed voltage and the voltage at the end of charging and discharging, phase transition abrupt change points are identified using the basic charging and discharging characteristics, dynamic parameters, and charge transfer resistance in the corresponding charging and discharging scenario. Corresponding protection operations are executed based on the identification results, which can significantly improve the accuracy and reliability of charging and discharging control, thereby ensuring battery safety and extending its service life.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery management technology, and in particular to a method and system for charging and discharging protection of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification. Background Technology

[0002] Lithium iron phosphate batteries have been widely used in electric vehicles, energy storage systems and portable electronic devices due to their high safety, long cycle life and cost advantages. They are one of the core energy storage devices in the new energy field, and their charge and discharge management strategies are directly related to battery life and application safety.

[0003] Currently, most mainstream battery management systems (BMS) use a fixed voltage threshold as the charge / discharge cutoff condition. This method defines the termination of charge / discharge by setting a preset terminal voltage threshold, and is widely adopted in the industry. However, this fixed threshold control method has significant limitations. It struggles to dynamically adapt to changes in battery state under different ambient temperatures and aging cycles, and cannot accurately match the intrinsic charge / discharge states of the battery's internal materials. This can easily lead to insufficient capacity utilization or overcharging and over-discharging, further exacerbating damage to the battery's internal structure and hindering its performance and safety throughout its entire lifecycle. Summary of the Invention

[0004] To address the aforementioned shortcomings in existing technologies, the present invention aims to provide a method for protecting the charge and discharge of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification. This method can accurately capture the intrinsic charge and discharge state of the battery, effectively adapt to different temperatures and aging conditions, and fundamentally avoid underutilization of capacity and overcharging / over-discharging caused by fixed voltage thresholds.

[0005] The above-mentioned objective of this invention is achieved through the following technical solution: A method for charge / discharge protection of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification includes: Obtain the historical total state of health (SOH), real-time voltage, real-time current, and charge transfer resistance of the target battery; The historical comprehensive SOH is used for key value matching to obtain charge and discharge dynamic parameters, which include single electrode duration, sliding window length, charging end voltage, discharging end voltage and voltage change rate threshold. The smoothed voltage obtained by performing a first-order low-pass filter on the real-time voltage is combined with the real-time current and the sliding window length to perform feature calculations, thereby obtaining the basic charging and discharging characteristics. When the smooth voltage is greater than the charging end voltage, the phase transition abrupt point is identified using the basic charging and discharging characteristics, the single electrode duration, the voltage change rate threshold, and the charge transfer resistance to obtain the phase transition abrupt point identification result in the charging scenario. When the smoothing voltage is less than the discharge end voltage, the phase transition abrupt point is identified using the basic charging and discharging characteristics, the single electrode duration, the voltage change rate threshold, and the charge transfer resistance to obtain the phase transition abrupt point identification result in the discharge scenario. The corresponding protection operation is executed based on the phase transition abruptness identification result in the charging scenario, and the corresponding protection operation is executed based on the phase transition abruptness identification result in the discharging scenario.

[0006] By adopting the above technical solution, the charging SOH is calculated based on the charging mutation capacity and the preset charging reference capacity, and the discharging SOH is calculated based on the discharging mutation capacity and the preset discharging reference capacity. Then, the historical comprehensive SOH is calculated by averaging the two values. This can accurately quantify the actual aging state of the battery, avoid the bias of single health parameter assessment, and provide an accurate basis for subsequent parameter matching. Using the historical comprehensive SOH to complete key value matching to obtain adaptive charging and discharging dynamic parameters, the control parameters can be adaptively adjusted according to the battery aging state, overcoming the limitation of traditional fixed voltage thresholds that cannot adapt to different operating conditions and different aging stages. After performing first-order low-pass filtering on the real-time voltage, feature calculations are performed in combination with real-time current and sliding window, which can effectively filter out electrical signal interference and extract features that accurately reflect the phase transition characteristics of the battery electrodes. The system identifies the fundamental characteristics of charging and discharging, laying a solid data foundation for phase transition identification. It identifies phase transition abrupt change points for both charging and discharging scenarios, accurately capturing the critical node where the battery's positive and negative electrode materials transition from two-phase coexistence to single-phase solid solution. This allows for precise determination of the battery's intrinsic charging and discharging critical state, rather than relying on rough judgments based on empirical voltage values. Finally, based on the scenario-based identification results, targeted protection operations are executed. This enables timely control of the charging and discharging process before electrode structure instability and side reactions occur, effectively preventing irreversible damage such as electrode lattice collapse, electrolyte decomposition, and negative electrode lithium plating caused by overcharging and over-discharging. Simultaneously, it maximizes battery capacity utilization efficiency, significantly improving battery safety and cycle life. This fundamentally solves the technical problems of poor adaptability, low identification accuracy, and easy damage to battery life and safety associated with traditional fixed voltage threshold control methods.

[0007] Preferably, the step of using the historical comprehensive SOH for bond value matching to obtain charge / discharge dynamic parameters includes: The search key is constructed using the historical comprehensive SOH. The preset dynamic parameter table is retrieved using the search key, and the charging and discharging dynamic parameters are obtained by matching.

[0008] By adopting the above technical solution, a dedicated search key is constructed based on the historical comprehensive SOH corresponding to the actual aging state of the battery. The preset experimentally calibrated dynamic parameter table can be accurately retrieved, and the charging and discharging dynamic parameters that are suitable for the current battery state can be quickly matched. This enables the control parameters to be adaptively adjusted as the battery ages, breaking through the limitations of poor universality and insufficient adaptability of traditional fixed parameters, and improving the accuracy of subsequent phase transition identification.

[0009] Preferably, the smoothed voltage obtained by first-order low-pass filtering of the real-time voltage is combined with the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging characteristics, including: The real-time voltage is subjected to a first-order low-pass filter to obtain a smoothed voltage; The instantaneous voltage change rate at the current moment is determined by using the smoothed voltage and the smoothed voltage at the previous moment. Obtain multiple historical instantaneous voltage change rates within the length of the sliding window; The average of the instantaneous voltage change rate at the current moment and the multiple historical instantaneous voltage change rates is used to obtain the average target change rate at the current moment; The differential capacity at the current moment is determined using the smoothed voltage, the smoothed voltage at the previous moment, and the real-time current. The basic charging and discharging characteristics include the instantaneous voltage change rate, the target change rate mean, and the differential capacity.

[0010] By adopting the above technical solution, high-frequency electromagnetic interference in the real-time voltage is first eliminated by first-order low-pass filtering to obtain a stable and smooth voltage. Then, the instantaneous voltage change rate, sliding window mean and differential capacity are calculated step by step. This can comprehensively extract the time-series electrical characteristics of battery charging and discharging and the electrode phase transition correlation characteristics, filter signal interference and weaken fluctuation errors, and provide stable and accurate core basic characteristics for subsequent phase transition abrupt point identification.

[0011] Preferably, when the smoothed voltage is greater than the charging end voltage, the phase transition abruptness point is identified using the basic charging and discharging characteristics, the single electrode duration, the voltage change rate threshold, and the charge transfer resistance to obtain the phase transition abruptness point identification result in the charging scenario, including: When the smooth voltage is greater than the charging end voltage, the instantaneous voltage change rate and the differential capacity are weighted together with a preset positive electrode coupling factor to obtain the lithium iron phosphate positive electrode phase change composition in the charging scenario. When the phase change of the lithium iron phosphate cathode, the instantaneous voltage change rate, and the average of the target change rate meet the preset first cathode triggering condition, the cathode triggering time is recorded. When the phase change of the lithium iron phosphate cathode, the average of the instantaneous voltage change rate and the target change rate do not meet the preset first cathode trigger condition, the process jumps to the step of performing the smoothed voltage obtained by first-order low-pass filtering on the real-time voltage, and performing feature calculations in combination with the real-time current and the sliding window length to obtain the basic charging and discharging characteristics. The preset first positive electrode triggering condition is specifically that the phase change fraction of the lithium iron phosphate positive electrode is greater than or equal to the preset feature score threshold, the instantaneous voltage change rate is greater than or equal to the voltage change rate threshold, and the average target change rate is greater than or equal to the voltage change rate threshold, and the duration for which all three conditions are met is greater than or equal to the single electrode duration. The charge transfer resistor is used as the graphite negative electrode phase change component in the charging scenario; When the phase change of the graphite negative electrode meets the preset first negative electrode triggering condition, the negative electrode triggering time is recorded; When the phase change of the graphite negative electrode does not meet the preset first negative electrode triggering condition, the process jumps to the step of performing the smoothed voltage obtained by first-order low-pass filtering on the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging characteristics. The preset first negative electrode triggering condition is specifically that the phase change fraction of the graphite negative electrode is greater than or equal to the preset feature score threshold, and the duration is greater than or equal to the single electrode duration; When the positive electrode trigger time and the negative electrode trigger time meet the preset first charging phase transition abrupt change point identification condition, it is determined that the target battery has reached the charging phase transition abrupt change point. When the positive electrode trigger time and the negative electrode trigger time do not meet the preset first charging phase transition abrupt change point identification condition, it is determined that the target battery has not reached the charging phase transition abrupt change point. The preset first charging phase transition abrupt change point identification condition is specifically that the positive electrode trigger time is less than the negative electrode trigger time, and the difference between the positive electrode trigger time and the negative electrode trigger time is within the preset positive electrode trigger time range.

[0012] By adopting the above technical solution, a phase change recognition logic is customized for charging scenarios. The positive electrode phase change degree is weighted and quantified. The positive and negative electrode trigger states are determined by multiple thresholds and duration conditions. Finally, the charging phase change abrupt point is locked by relying on the timing difference rule. This fits the phase change sequence of the positive and negative electrodes at the end of charging, avoids misjudgment of a single feature, accurately identifies the charging critical protection node, and avoids battery damage caused by overcharging from the source.

[0013] Preferably, when the smoothing voltage is less than the discharge end voltage, the phase transition abruptness point is identified using the basic charge / discharge characteristics, the single-electrode duration, the voltage change rate threshold, and the charge transfer resistance to obtain the phase transition abruptness point identification result under the discharge scenario, including: When the smoothing voltage is less than the discharge terminal voltage, the charge transfer resistor is used as the graphite negative electrode phase transition component in the discharge scenario; When the phase change of the graphite negative electrode, the absolute value of the instantaneous voltage change rate, and the absolute value of the average target change rate satisfy the preset second negative electrode triggering condition, the negative electrode triggering time is recorded. When the phase change of the graphite negative electrode, the absolute value of the instantaneous voltage change rate, and the absolute value of the average target change rate do not meet the preset second negative electrode triggering condition, the process jumps to the step of performing the smoothed voltage obtained by performing first-order low-pass filtering on the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging characteristics. The preset second negative electrode triggering condition is specifically that the phase change fraction of the graphite negative electrode is greater than or equal to the preset feature score threshold, the absolute value of the instantaneous voltage change rate is greater than or equal to the voltage change rate threshold, and the absolute value of the average target change rate is greater than or equal to the voltage change rate threshold, and the duration for which the three conditions are simultaneously satisfied is greater than or equal to the duration of the single electrode. The absolute value of the instantaneous voltage change rate and the differential capacity are weighted together with a preset positive electrode coupling factor to obtain the phase change composition of the lithium iron phosphate positive electrode under the discharge scenario; When the phase change of the lithium iron phosphate cathode meets the preset second cathode trigger condition, the cathode trigger time is recorded; When the phase change of the lithium iron phosphate cathode does not meet the preset second cathode trigger condition, the process jumps to the step of performing the smoothed voltage obtained by first-order low-pass filtering of the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging characteristics. The preset second positive electrode triggering condition is specifically that the phase change fraction of the lithium iron phosphate positive electrode is greater than or equal to the preset feature score threshold, and the duration is greater than or equal to the single electrode duration; When the positive electrode trigger time and the negative electrode trigger time meet the preset second discharge phase transition abrupt change point identification condition, it is determined that the target battery has reached the discharge phase transition abrupt change point. If the positive electrode trigger time and the negative electrode trigger time do not meet the preset second discharge phase transition abrupt change point identification condition, then it is determined that the target battery has not reached the discharge phase transition abrupt change point. The preset second discharge phase transition abrupt change point identification condition is specifically that the negative electrode trigger time is less than the positive electrode trigger time, and the difference between the positive electrode trigger time and the negative electrode trigger time is within the preset negative electrode trigger time range.

[0014] By adopting the above technical solution, the identification logic is optimized to match the electrode phase transition characteristics in the discharge scenario. The negative electrode phase transition state is prioritized, and the absolute value of the voltage change rate is used to match the discharge voltage change law. Combined with the positive and negative electrode triggering timing rules, the discharge phase transition abrupt point is accurately determined. This is different from the identification logic in the charging scenario, and the critical discharge node is captured in a targeted manner, effectively preventing the problems of electrode structure collapse and electrolyte decomposition caused by over-discharge.

[0015] Preferably, the step of performing corresponding protection operations based on the phase transition abruptness identification results in the charging scenario, and performing corresponding protection operations based on the phase transition abruptness identification results in the discharging scenario, includes: When the phase transition abruptness identification result in the charging scenario indicates that the target battery has not reached the charging phase transition abruptness, the process jumps to the step of performing the smoothed voltage obtained by performing first-order low-pass filtering on the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging features. When the phase transition abruptness identification result in the charging scenario indicates that the target battery has reached the charging phase transition abruptness point, the charging current is controlled to be reduced in stages until it is reduced to a preset charging current threshold, at which point the main charging contactor is disconnected. When the phase transition abruptness identification result in the discharge scenario indicates that the target battery has not reached the discharge phase transition abruptness, the process jumps to the step of performing the smoothed voltage obtained by first-order low-pass filtering on the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging features. When the phase transition abruptness identification result in the discharge scenario indicates that the target battery has reached the discharge phase transition abruptness point, the discharge current is controlled to be reduced in stages until it is reduced to a preset discharge current threshold, at which point the discharge main contactor is cut off.

[0016] By adopting the above technical solution, closed-loop protection operation is performed based on the phase change identification result. When the sudden change point is not reached, continuous cyclic monitoring ensures normal charging and discharging. When the sudden change point is reached, the main circuit is cut off after gradual current reduction and control. This avoids circuit impact caused by instantaneous power outage and can terminate charging and discharging in time before the electrode structure becomes unstable. It takes into account the stability of charging and discharging control and the effectiveness of battery protection, and completely solves the problems of lag and misjudgment of traditional fixed threshold protection.

[0017] Preferably, obtaining the historical comprehensive SOH of the target battery includes: Obtain the charging and discharging transient capacities of the target battery; The ratio of the sudden charging capacity to the preset charging reference capacity is converted into a percentage to obtain the charging SOH; The ratio of the discharge mutation capacity to the preset discharge reference capacity is converted into a percentage to obtain the discharge SOH; The sum of the charging SOH and the discharging SOH is calculated, and the average of the sum is calculated to obtain the historical comprehensive SOH.

[0018] By adopting the above technical solution, the corresponding SOH sub-parameters are calculated based on the bidirectional change capacity of the battery during charging and discharging, and then the comprehensive health status parameters are obtained by averaging. This approach can take into account the capacity decay during charging and discharging, avoid the one-sidedness of a single SOH assessment, accurately quantify the actual aging degree of the battery, and provide a real and reliable core basis for subsequent dynamic parameter matching.

[0019] The second objective of this invention is to provide a lithium iron phosphate graphite battery charge and discharge protection system based on phase transition abrupt change point identification. This system can accurately capture the intrinsic charge and discharge state of the battery, effectively adapt to different temperatures and aging conditions, and fundamentally avoid insufficient capacity utilization and overcharging / over-discharging caused by fixed voltage thresholds.

[0020] The second objective of this invention is achieved through the following technical solution: A charge / discharge protection system for lithium iron phosphate graphite batteries based on phase transition abrupt change point identification includes: The data acquisition module is used to acquire the historical overall SOH, real-time voltage, real-time current, and charge transfer resistance of the target battery; The key value matching module is used to perform key value matching using the historical comprehensive SOH to obtain charge and discharge dynamic parameters, which include single electrode duration, sliding window length, charging end voltage, discharging end voltage and voltage change rate threshold. The feature calculation module is used to perform feature calculations on the smoothed voltage obtained by first-order low-pass filtering of the real-time voltage, and combine it with the real-time current and the sliding window length to obtain the basic charging and discharging features. The charging phase transition abrupt point identification module is used to identify the phase transition abrupt point by using the basic charging and discharging characteristics, the single electrode duration, the voltage change rate threshold, and the charge transfer resistance when the smooth voltage is greater than the charging end voltage, so as to obtain the phase transition abrupt point identification result in the charging scenario. The discharge phase transition abrupt point identification module is used to identify the phase transition abrupt point by using the basic charging and discharging characteristics, the single electrode duration, the voltage change rate threshold, and the charge transfer resistance when the smoothing voltage is less than the discharge end voltage, so as to obtain the phase transition abrupt point identification result in the discharge scenario. The protection operation module is used to perform corresponding protection operations based on the phase transition abruptness identification results in the charging scenario and to perform corresponding protection operations based on the phase transition abruptness identification results in the discharging scenario.

[0021] By adopting the above technical solution, the data acquisition module synchronously collects the historical comprehensive SOH, real-time voltage, real-time current, and charge transfer resistance of the target battery, providing multi-dimensional raw data support for charge and discharge protection. The key value matching module completes dynamic parameter matching based on the historical comprehensive SOH, which can adaptively output charge and discharge control parameters adapted to the battery aging state, thus overcoming the application limitations of traditional fixed thresholds. The feature calculation module filters the voltage signal and extracts basic features such as instantaneous voltage change rate, mean change rate, and differential capacity, which can effectively eliminate interference and accurately characterize the electrode phase transition characteristics. The charging phase transition abrupt change point identification module and the discharging phase transition abrupt change point identification module identify the critical nodes of phase transition in the charging and discharging scenarios, which can accurately capture the moment of phase transition abrupt change of the positive and negative electrode materials and accurately determine the intrinsic charge and discharge state of the battery. Finally, the protection operation module performs graded current reduction and loop cut-off protection based on the identification results, which can terminate the charging and discharging process in time before the battery electrode structure becomes unstable, avoid battery damage caused by overcharging and over-discharging, improve battery safety and cycle life, and realize intelligent and precise protection for the entire charging and discharging process of lithium iron phosphate graphite batteries.

[0022] The third objective of this invention is to provide an electronic device that can accurately capture the intrinsic charge and discharge state of a battery, effectively adapt to different temperatures and aging conditions, and fundamentally avoid underutilization of capacity and overcharging / over-discharging caused by a fixed voltage threshold.

[0023] The above-mentioned objective three of this invention is achieved through the following technical solution: An electronic device includes a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and executed the lithium iron phosphate graphite battery charge and discharge protection method based on phase transition abrupt point identification as described above.

[0024] The fourth objective of this invention is to provide a computer-readable storage medium capable of storing corresponding programs, which can accurately capture the intrinsic charge and discharge state of the battery, effectively adapt to different temperatures and aging conditions, and fundamentally avoid underutilization of capacity and overcharging / over-discharging caused by fixed voltage thresholds.

[0025] The fourth objective of this invention is achieved through the following technical solution: A computer-readable storage medium storing a computer program that can be loaded by a processor and executed by the above-described method for protecting lithium iron phosphate graphite batteries based on phase transition abrupt point identification.

[0026] In summary, the present invention has at least one of the following beneficial technical effects: This invention first obtains the historical comprehensive state of harmonics (SOH), real-time voltage, real-time current, and charge transfer resistance of the target battery. Using the historical comprehensive SOH, key-value matching is performed to obtain dynamic charging and discharging parameters adapted to the current battery state. Then, the real-time voltage is subjected to a first-order low-pass filter, and feature calculations are performed using the real-time current and the sliding window length to obtain basic charging and discharging characteristics. Subsequently, based on the relationship between the smoothed voltage and the voltage at the end of charging and discharging, phase transition abrupt change points are identified in the corresponding charging and discharging scenario using the basic charging and discharging characteristics, dynamic parameters, and charge transfer resistance. Corresponding protection operations are then executed based on the identification results. This invention does not use a traditional fixed voltage threshold for charging and discharging control. Instead, it achieves adaptive matching to different battery aging states and environmental temperature changes by matching dynamic parameters with SOH. Simultaneously, it accurately locates the battery's intrinsic charging and discharging critical state by identifying phase transition abrupt change points, rather than relying on fixed voltage empirical values ​​to determine the charging and discharging termination point. This effectively solves the problem of insufficient capacity utilization or overcharging and over-discharging caused by the inability of fixed thresholds to adapt to changes in operating conditions, reduces the risk of damage to the battery's internal structure, significantly improves the accuracy and reliability of charging and discharging control, and thus ensures battery safety and extends its service life. Attached Figure Description

[0027] Figure 1 This is a schematic flowchart of a charging and discharging protection method for lithium iron phosphate graphite batteries based on phase transition abrupt change point identification provided in an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of the charge-discharge curve of a graphite half-cell (C / Li) provided in an embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of the charge-discharge curves of a lithium iron phosphate half-cell (LFP / Li) provided in an embodiment of the present invention.

[0030] Figure 4 This is a schematic diagram of the charge and discharge curves of a 50Ah soft-pack LFP / C full battery at different temperatures and different rates, provided in the embodiments of the present invention.

[0031] Figure 5 This is a schematic diagram illustrating the comparison of cycle life data of individual battery cells provided in an embodiment of the present invention.

[0032] Figure 6 This is a structural block diagram of a lithium iron phosphate graphite battery charge and discharge protection system based on phase transition abrupt change point identification provided in an embodiment of the present invention. Detailed Implementation

[0033] This invention provides a method and system for protecting lithium iron phosphate graphite batteries during charging and discharging based on phase transition abrupt change point identification. It addresses the technical problem of existing lithium iron phosphate battery charging and discharging control methods that use fixed voltage thresholds, making it difficult to accurately identify the battery's intrinsic charging and discharging state, which easily leads to insufficient capacity utilization or overcharging and over-discharging. The method can accurately capture the battery's intrinsic charging and discharging state, effectively adapt to different temperatures and aging conditions, and fundamentally avoid the insufficient capacity utilization and overcharging / over-discharging issues caused by fixed voltage thresholds.

[0034] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0035] It should be noted that, in the embodiments of this invention, when the relevant object information and other related data are used in specific products or technologies, permission or consent from the object is required, and the collection, use, and processing of the relevant data must comply with the relevant laws, regulations, and standards of the relevant countries and regions. In other words, if the embodiments of this invention involve data related to an object, it must be obtained with the object's authorization and consent, the authorization and consent of relevant departments, and in accordance with the relevant laws, regulations, and standards of the country and region. If personal information is involved in the embodiments, the acquisition of all personal information requires the individual's consent; if sensitive information is involved, the separate consent of the information subject is required. The embodiments also need to be implemented with the object's authorization and consent.

[0036] It should be noted that the terms "first," "second," etc., used in this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented in orders other than those illustrated or described herein. The implementations described in the following exemplary embodiments do not represent all implementations consistent with this disclosure.

[0037] Furthermore, the term "and / or" 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, or B existing alone. Additionally, the character " / " in this article, unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship. Example

[0038] Please see Figure 1The present invention provides a method for charge and discharge protection of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification, comprising: Step 101: Obtain the historical total SOH, real-time voltage, real-time current, and charge transfer resistance of the target battery.

[0039] In this embodiment of the invention, the historical comprehensive SOH is retrieved from the storage unit of the battery management system (BMS) associated with the target battery. This parameter is calculated by the BMS based on multi-dimensional data such as the cumulative number of battery cycles, the ratio of actual usable capacity to rated capacity, and the rate of change of DC internal resistance, which can accurately characterize the current aging degree of the battery. The real-time voltage is synchronously acquired by a high-precision voltage acquisition module at a sampling frequency of 10Hz for the terminal voltage of the individual battery cells. The real-time current is acquired by a Hall current sensor connected in series in the main circuit of the battery at the same sampling frequency for the charging and discharging current signal. During the acquisition process, a first-order low-pass filter is simultaneously performed to eliminate electromagnetic interference in the circuit. The charge transfer resistance is obtained by an online electrochemical impedance spectroscopy module by fitting and extracting impedance response data in the 1Hz to 10kHz frequency band under static or low-current pulse disturbance conditions, or by calculating based on the transient response curves of real-time voltage and current, ensuring that the acquisition of each parameter is synchronous and the accuracy meets the requirements for subsequent phase transition abrupt point identification.

[0040] Further, step 101 may include the following sub-steps: S11. Obtain the charging and discharging transient capacities of the target battery. S12. Convert the ratio of the charging mutation capacity to the preset charging reference capacity into a percentage to obtain the charging SOH; S13. Convert the ratio of the discharge mutation capacity to the preset discharge reference capacity into a percentage to obtain the discharge SOH; S14. The sum of the charging SOH and the discharging SOH is calculated, and the average of the sum is calculated to obtain the historical comprehensive SOH.

[0041] In this embodiment of the invention, S11, the charging mutation capacity and the discharging mutation capacity of the target battery are obtained, wherein the charging mutation capacity is the cumulative charging capacity corresponding to the phase transition mutation point during the charging process of the target battery, and the discharging mutation capacity is the cumulative discharging capacity corresponding to the phase transition mutation point during the discharging process. Both types of capacity data are collected and stored through the coulomb integral module of the battery management system. S12. Convert the ratio of the sudden charging capacity to the preset charging reference capacity into a percentage to obtain the charging SOH. The calculation formula is as follows:

[0042] In the formula, For charging SOH; This refers to the charging mutation capacity; Preset charging baseline capacity; S13. Convert the ratio of the discharge mutation capacity to the preset discharge reference capacity into a percentage to obtain the discharge SOH. The calculation formula is as follows:

[0043] In the formula, For discharge SOH; This refers to the discharge mutation capacity; The preset discharge reference capacity; S14. The sum of the charging SOH and discharging SOH is calculated, and the average of the sum is calculated to obtain the historical comprehensive SOH. The calculation formula is as follows:

[0044] In the formula, To achieve historical SOH, the system simultaneously acquires the real-time voltage of the target battery through the high-precision voltage acquisition unit of the battery management system, collects the real-time current using a Hall current sensor connected in series in the main circuit, and obtains the charge transfer resistance by fitting the battery transient response data through an online electrochemical impedance spectroscopy module. All parameters are acquired synchronously to ensure the accuracy of feature calculation and phase transition identification.

[0045] Historical overall state of health (SOH) is a core health parameter that comprehensively reflects the aging degree and usable capacity decay level of the target battery; real-time voltage refers to the raw signal of the battery cell terminal voltage collected in real time by the battery management system; real-time current is the real-time collected signal of the battery main circuit charge and discharge current; charge transfer resistance is a parameter that characterizes the electrochemical reaction impedance at the interface between the battery electrode and the electrolyte and reflects the electrochemical activity of the electrode; charge and discharge dynamic parameters are a set of core control parameters that adaptively adjust according to the battery state, specifically including single electrode duration, sliding window length, charging end voltage, discharging end voltage, and voltage change rate threshold; single electrode duration is the minimum effective duration threshold for determining the electrode phase transition trigger state; sliding window length is the time-series data sampling window range used to calculate the average voltage change rate; charging end voltage is the threshold for determining whether the battery has entered the charging phase transition trigger state. The critical voltage value for the phase transition identification stage at the end of charging; the critical voltage value for determining whether the battery has entered the phase transition identification stage at the end of discharging; the voltage change rate threshold is the critical change value for determining whether a phase transition occurs; the smoothed voltage is the stable voltage value after filtering the real-time voltage to remove high-frequency interference; the basic charging and discharging characteristics are the core electrical feature set used for phase transition abrupt change point identification; the phase transition abrupt change point is the critical node where the positive and negative electrode materials of the battery change from a two-phase coexistence state to a single-phase solid solution state; the phase transition abrupt change point identification result in the charging scenario is the judgment conclusion for determining whether the battery has reached the critical protection state for charging; the phase transition abrupt change point identification result in the discharging scenario is the judgment conclusion for determining whether the battery has reached the critical protection state for discharging; the protection operation is the charging and discharging control and circuit on / off control action executed based on the phase transition abrupt change point identification result.

[0046] The charging surge capacity is the cumulative charging capacity value when the battery is charged to the phase transition surge point; the discharging surge capacity is the cumulative discharging capacity value when the battery is discharged to the phase transition surge point; the preset charging reference capacity is the standard charging surge capacity reference value of the battery in its brand-new state; the charging SOH is a battery health state sub-parameter calculated based on the ratio of the charging surge capacity to the preset charging reference capacity; the preset discharging reference capacity is the standard discharging surge capacity reference value of the battery in its brand-new state; the discharging SOH is a battery health state sub-parameter calculated based on the ratio of the discharging surge capacity to the preset discharging reference capacity; the historical comprehensive SOH is a comprehensive battery health state parameter calculated by summing the charging SOH and the discharging SOH and taking the average.

[0047] Step 102: Use historical comprehensive SOH to perform key value matching to obtain charge and discharge dynamic parameters, including single electrode duration, sliding window length, charging end voltage, discharging end voltage and voltage change rate threshold.

[0048] Furthermore, step 102 may include the following sub-steps: S21. Use historical comprehensive SOH to construct search keys; S22. Use the search key to search the preset dynamic parameter table and match the charging and discharging dynamic parameters.

[0049] In this embodiment of the invention, the historical comprehensive SOH calculated in step 101 is used to construct a search key. The numerical range of the historical comprehensive SOH is used as a unique search identifier to form a standardized search key that accurately corresponds to the current aging state of the battery. The search key is used to traverse and search a preset dynamic parameter table that has been calibrated through multiple batches of lithium iron phosphate / graphite battery aging experiments. This preset dynamic parameter table has a built-in one-to-one mapping relationship between different historical comprehensive SOH ranges and single electrode duration, sliding window length, charging end voltage, discharging end voltage, and voltage change rate threshold. After precise matching of the key value, a complete set of charge and discharge dynamic parameters adapted to the current aging state of the target battery are directly output, realizing the adaptive adjustment of charge and discharge control parameters according to the aging state of the battery.

[0050] The search key is a standardized search identifier built around the historical comprehensive SOH and used for precise parameter matching. The preset dynamic parameter table is a data table that has been calibrated in advance through multiple batches of battery aging experiments and stores the mapping relationship between different historical comprehensive SOH ranges and corresponding charge and discharge dynamic parameters.

[0051] Step 103: Perform a first-order low-pass filter on the real-time voltage to obtain a smoothed voltage. Combine the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging characteristics.

[0052] Furthermore, step 103 may include the following sub-steps: S31. Perform a first-order low-pass filter on the real-time voltage to obtain a smoothed voltage. S32. Using the smoothed voltage and the smoothed voltage of the previous moment, determine the instantaneous voltage change rate at the current moment; S33. Obtain multiple historical instantaneous voltage change rates within the sliding window length; S34. The average value of the target rate of change at the current moment is obtained by averaging the instantaneous voltage change rate at the current moment with multiple historical instantaneous voltage change rates. S35. Use the smoothed voltage, the smoothed voltage of the previous moment, and the real-time current to determine the differential capacity at the current moment. The basic characteristics of charging and discharging include instantaneous voltage change rate, target change rate mean, and differential capacity.

[0053] In this embodiment of the invention, S31, the acquired real-time voltage is subjected to a first-order low-pass filter to remove high-frequency electromagnetic interference in the signal, resulting in a smooth voltage. The calculation formula for the first-order low-pass filter is as follows:

[0054] In the formula, Smooth the voltage at the current moment; These are the filter coefficients; This represents the real-time voltage at the current moment. The voltage is the smoothed voltage from the previous moment; S32. The instantaneous voltage change rate at the current moment is determined by combining the difference between the smoothed voltage at the current moment and the smoothed voltage at the previous moment with the sampling time interval. The calculation formula is as follows:

[0055] In the formula, The instantaneous rate of change of voltage at the current moment; The sampling time interval for the voltage signal; S33. Based on the sliding window length obtained in step 102, retrieve and obtain the instantaneous voltage change rate data of multiple consecutive historical moments within the sliding window range; S34. Calculate the arithmetic mean of the current instantaneous voltage change rate and all historical instantaneous voltage change rates within the sliding window to obtain the target change rate mean at the current moment. The calculation formula is as follows:

[0056] In the formula, This represents the average rate of change of the target at the current moment. The length of the sliding window; Let be the instantaneous voltage change rate at time i within the sliding window; S35. Using the smoothed voltage, the smoothed voltage from the previous moment, and the real-time current, the differential capacity at the current moment is determined by calculation. The calculation formula is as follows:

[0057] In the formula, The capacity is the differential capacity at the current moment; The current is the real-time current at the current moment; the instantaneous voltage change rate, the average target change rate, and the differential capacity obtained through the above calculations together constitute the basic characteristics of charging and discharging, providing core data support for the identification of phase transition abrupt points under different charging and discharging scenarios.

[0058] First-order low-pass filtering is a digital filtering method used to filter out high-frequency electromagnetic interference in real-time voltage signals and improve the stability of voltage signals; instantaneous voltage change rate is the change in smoothed voltage at the current moment compared to the smoothed voltage at the previous moment within a unit sampling time; historical instantaneous voltage change rate is the instantaneous voltage change rate data corresponding to past moments within the sliding window range; target change rate mean is the average value calculated from the instantaneous voltage change rate at the current moment and all historical instantaneous voltage change rates within the sliding window; differential capacity is a parameter that reflects the capacity change corresponding to a unit change in voltage and characterizes the phase transition characteristics of electrodes. Instantaneous voltage change rate, target change rate mean, and differential capacity together constitute the basic characteristics of charging and discharging.

[0059] Step 104: When the smoothing voltage is greater than the charging end voltage, the phase transition abrupt point is identified using the basic characteristics of charging and discharging, single electrode duration, voltage change rate threshold, and charge transfer resistance to obtain the phase transition abrupt point identification result in the charging scenario.

[0060] Furthermore, step 104 may include the following sub-steps: S41. When the smooth voltage is greater than the charging end voltage, the instantaneous voltage change rate and differential capacity are used, combined with the preset positive electrode coupling factor, to obtain the lithium iron phosphate positive electrode phase change composition under the charging scenario. S42. When the average values ​​of the phase change composition, instantaneous voltage change rate, and target change rate of the lithium iron phosphate cathode meet the preset first cathode triggering condition, record the cathode triggering time. S43. When the phase change of the lithium iron phosphate cathode, the instantaneous voltage change rate, and the average of the target change rate do not meet the preset first cathode trigger condition, the process jumps to execute the step of performing a smooth voltage obtained by first-order low-pass filtering of the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging characteristics. The preset first positive electrode triggering condition is that the phase change fraction of the lithium iron phosphate positive electrode is greater than or equal to the preset feature score threshold, the instantaneous voltage change rate is greater than or equal to the voltage change rate threshold, and the target change rate average is greater than or equal to the voltage change rate threshold, and the duration of the three conditions being met simultaneously is greater than or equal to the duration of a single electrode. S44. The charge transfer resistor is used as the phase transition component of the graphite negative electrode in the charging scenario; S45. When the phase change of the graphite negative electrode meets the preset first negative electrode triggering condition, record the negative electrode triggering time. S46. When the phase change of the graphite negative electrode does not meet the preset first negative electrode triggering condition, jump to execute the step of smoothing the real-time voltage by performing a first-order low-pass filter on the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging characteristics. The preset first negative electrode triggering condition is that the phase change fraction of the graphite negative electrode is greater than or equal to the preset feature score threshold, and the duration is greater than or equal to the duration of a single electrode. S47. When the positive electrode trigger time and the negative electrode trigger time meet the preset first charging phase transition abrupt change point identification condition, it is determined that the target battery has reached the charging phase transition abrupt change point. S48. When the positive electrode trigger time and the negative electrode trigger time do not meet the preset first charging phase transition abrupt change point identification condition, it is determined that the target battery has not reached the charging phase transition abrupt change point. The preset first charging phase transition abrupt change point identification condition is that the positive electrode trigger time is less than the negative electrode trigger time, and the difference between the positive electrode trigger time and the negative electrode trigger time is within the preset positive electrode trigger time range.

[0061] In this embodiment of the invention, S41, when the smoothing voltage is greater than the charging end voltage, the instantaneous voltage change rate and differential capacity in the basic characteristics of charging and discharging are used, combined with a preset positive electrode coupling factor, for weighted calculation to obtain the phase transition composition of the lithium iron phosphate positive electrode in the charging scenario. The calculation formula is as follows:

[0062] In the formula, The phase change of the lithium iron phosphate cathode at time t in a charging scenario; The preset positive coupling factor; Let be the instantaneous voltage change rate at time t; Let be the differential capacity at time t; S42. Determine whether the phase change composition, instantaneous voltage change rate and target change rate of the lithium iron phosphate cathode meet the preset first cathode triggering condition. The condition is that the phase change composition of the lithium iron phosphate cathode is greater than or equal to the preset feature score threshold, the instantaneous voltage change rate is greater than or equal to the voltage change rate threshold, and the target change rate is greater than or equal to the voltage change rate threshold. The duration of the three conditions being met simultaneously is greater than or equal to the duration of a single electrode. If the condition is met, record the current moment as the cathode triggering time. S43. If the preset first positive electrode trigger condition is not met, immediately jump to step 103 to perform first-order low-pass filtering on the real-time voltage to obtain a smooth voltage, and perform feature calculations based on the real-time current and the sliding window length to obtain basic charging and discharging characteristics, and re-perform data calculations and condition judgments. S44. The charge transfer resistor obtained in step 101 is directly used as the graphite negative electrode phase transition component in the charging scenario. S45. Determine whether the phase change component of the graphite negative electrode meets the preset first negative electrode triggering condition. The condition is that the phase change component of the graphite negative electrode is greater than or equal to the preset feature score threshold, and the duration of meeting the condition is greater than or equal to the duration of a single electrode. If the condition is met, record the current time as the negative electrode triggering time. S46. If the preset first negative electrode triggering condition is not met, jump to step 103 to perform first-order low-pass filtering of the real-time voltage to obtain a smooth voltage, and combine the real-time current and the sliding window length to perform feature calculation to obtain the basic charging and discharging characteristics, and re-perform feature calculation and trigger determination. S47. After recording the positive and negative trigger times, determine whether they meet the preset first charging phase transition abrupt change point identification condition. The condition is that the positive trigger time is less than the negative trigger time, and the difference between the positive and negative trigger times is within the preset positive trigger time range. If the condition is met, it is determined that the target battery has reached the charging phase transition abrupt change point. S48. If the positive electrode trigger time and the negative electrode trigger time do not meet the preset first charging phase transition mutation point identification condition, it is determined that the target battery has not reached the charging phase transition mutation point, and the feature calculation and phase transition identification process is continuously executed in a loop until the identification condition is met or the charging process is terminated.

[0063] The preset positive electrode coupling factor is a fixed allocation coefficient used for weighted calculation of instantaneous voltage change rate and differential capacity in the charging scenario; the lithium iron phosphate positive electrode phase change component is a scoring parameter that quantifies the degree of positive electrode phase change in the charging scenario; the preset first positive electrode triggering condition is a comprehensive judgment rule for determining the triggering of positive electrode phase change in the charging scenario, specifically including multiple limitations on phase change component, voltage change rate, and duration; the positive electrode triggering time is the corresponding moment when the preset first positive electrode triggering condition is met; the preset feature score threshold is the minimum score critical value for determining electrode phase change triggering; the graphite negative electrode phase change component is a phase change parameter of the negative electrode directly characterized by charge transfer resistance in the charging scenario; the preset first negative electrode triggering condition is a judgment rule for determining the triggering of negative electrode phase change in the charging scenario, including phase change component and duration limitation; the negative electrode triggering time is the corresponding moment when the preset first negative electrode triggering condition is met; the preset first charging phase change abrupt change point identification condition is a timing judgment rule for finally determining that the battery has reached the phase change abrupt change point in the charging scenario; the preset positive electrode triggering time interval is the allowable range of the difference between positive and negative electrode triggering times in the charging scenario.

[0064] Step 105: When the smoothing voltage is less than the discharge end voltage, the phase transition abrupt point is identified using the basic characteristics of charging and discharging, single electrode duration, voltage change rate threshold, and charge transfer resistance to obtain the phase transition abrupt point identification results under the discharge scenario.

[0065] Furthermore, step 105 may include the following sub-steps: S51. When the smoothing voltage is less than the discharge end voltage, the charge transfer resistor is used as the graphite negative electrode phase transition component in the discharge scenario. S52. When the absolute values ​​of the graphite negative electrode phase change component, the instantaneous voltage change rate, and the average target change rate meet the preset second negative electrode triggering condition, record the negative electrode triggering time. S53. When the absolute values ​​of the graphite negative electrode phase change component, the instantaneous voltage change rate, and the target change rate mean do not meet the preset second negative electrode triggering condition, jump to execute the step of performing a smooth voltage obtained by first-order low-pass filtering of the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging characteristics. The preset second negative electrode triggering conditions are as follows: the phase change fraction of the graphite negative electrode is greater than or equal to the preset feature score threshold, the absolute value of the instantaneous voltage change rate is greater than or equal to the voltage change rate threshold, and the absolute value of the average target change rate is greater than or equal to the voltage change rate threshold. The duration for which all three conditions are met is greater than or equal to the duration of a single electrode. S54. The absolute value of the instantaneous voltage change rate and the differential capacity are used, combined with the preset positive electrode coupling factor for weighting, to obtain the phase change composition of the lithium iron phosphate positive electrode under the discharge scenario. S55. When the phase change of the lithium iron phosphate cathode meets the preset second cathode trigger condition, the cathode trigger time is recorded. S56. When the phase change of the lithium iron phosphate cathode does not meet the preset second cathode triggering condition, jump to execute the step of smoothing the voltage obtained by first-order low-pass filtering of the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculation to obtain the basic charging and discharging characteristics. The preset second positive electrode triggering condition is that the phase change fraction of the lithium iron phosphate positive electrode is greater than or equal to the preset feature score threshold, and the duration is greater than or equal to the single electrode duration. S57. When the positive electrode trigger time and the negative electrode trigger time meet the preset second discharge phase transition abrupt change point identification conditions, it is determined that the target battery has reached the discharge phase transition abrupt change point. S58. When the positive electrode trigger time and the negative electrode trigger time do not meet the preset second discharge phase transition abrupt change point identification conditions, it is determined that the target battery has not reached the discharge phase transition abrupt change point. The preset second discharge phase transition abrupt change point identification condition is that the negative electrode trigger time is less than the positive electrode trigger time, and the difference between the positive electrode trigger time and the negative electrode trigger time is within the preset negative electrode trigger time range.

[0066] In this embodiment of the invention, S51, when the smoothing voltage is less than the discharge end voltage, the charge transfer resistance obtained in step 101 is directly used as the graphite negative electrode phase change component in the discharge scenario. S52. Determine whether the absolute values ​​of the phase change component of the graphite negative electrode, the instantaneous voltage change rate, and the target change rate mean value meet the preset second negative electrode triggering condition. The condition is that the phase change component of the graphite negative electrode is greater than or equal to the preset feature score threshold, the absolute value of the instantaneous voltage change rate is greater than or equal to the voltage change rate threshold, and the absolute value of the target change rate mean value is greater than or equal to the voltage change rate threshold. The duration for which all three conditions are met is greater than or equal to the duration of a single electrode. If the condition is met, record the current moment as the negative electrode triggering time. S53. If the preset second negative electrode trigger condition is not met, immediately jump to the step 103 to perform first-order low-pass filtering on the real-time voltage to obtain a smooth voltage, and perform feature calculations in combination with the real-time current and the sliding window length to obtain the basic characteristics of charging and discharging, and re-perform data calculations and condition judgments. S54. Using the absolute value of the instantaneous voltage change rate and the differential capacity, combined with a preset positive electrode coupling factor, a weighted calculation is performed to obtain the phase transition composition of the lithium iron phosphate positive electrode under the discharge scenario. The calculation formula is as follows:

[0067] In the formula, The phase change of the lithium iron phosphate cathode at time t under discharge conditions; The preset positive coupling factor; The absolute value of the instantaneous rate of change of voltage at time t; Let be the differential capacity at time t; S55. Determine whether the phase change component of the lithium iron phosphate cathode meets the preset second cathode triggering condition. The condition is that the phase change component of the lithium iron phosphate cathode is greater than or equal to the preset feature score threshold, and the duration of meeting the condition is greater than or equal to the duration of a single electrode. If the condition is met, record the current time as the cathode triggering time. S56. If the preset second positive electrode triggering condition is not met, jump to step 103 to perform first-order low-pass filtering of the real-time voltage to obtain a smooth voltage, and combine the real-time current and the sliding window length to perform feature calculation to obtain the basic charging and discharging characteristics, and re-perform feature calculation and trigger determination. S57. After recording the negative electrode trigger time and the positive electrode trigger time, determine whether they meet the preset second discharge phase transition abrupt change point identification condition. The condition is that the negative electrode trigger time is less than the positive electrode trigger time, and the difference between the positive electrode trigger time and the negative electrode trigger time is within the preset negative electrode trigger time range. If the condition is met, it is determined that the target battery has reached the discharge phase transition abrupt change point. S58. If the positive electrode trigger time and the negative electrode trigger time do not meet the preset second discharge phase transition mutation point identification condition, it is determined that the target battery has not reached the discharge phase transition mutation point, and the feature calculation and phase transition identification process is continuously executed in a loop until the identification condition is met or the discharge process is terminated.

[0068] The phase transition component of the graphite negative electrode is a quantitative parameter of the negative electrode phase transition directly characterized by charge transfer resistance under discharge scenarios; the preset second negative electrode triggering condition is a comprehensive judgment rule for determining the triggering of the negative electrode phase transition under discharge scenarios, including multiple limitations such as phase transition component, absolute value of voltage change rate, and duration; the phase transition component of the lithium iron phosphate positive electrode is a scoring parameter that quantitatively characterizes the degree of positive electrode phase transition under discharge scenarios; the preset second positive electrode triggering condition is a judgment rule for determining the triggering of the positive electrode phase transition under discharge scenarios, including phase transition component and duration limitation; the preset second discharge phase transition abrupt change point identification condition is a timing judgment rule for finally determining that the battery has reached the phase transition abrupt change point under discharge scenarios; the preset negative electrode triggering time interval is the allowable range of the difference between the positive and negative electrode triggering times under discharge scenarios.

[0069] Step 106: Execute the corresponding protection operation based on the phase transition abruptness identification result in the charging scenario, and execute the corresponding protection operation based on the phase transition abruptness identification result in the discharging scenario.

[0070] Furthermore, step 106 may include the following sub-steps: S61. When the phase transition abruptness identification result in the charging scenario is that the target battery has not reached the charging phase transition abruptness, jump to execute the step of performing a smooth voltage obtained by performing a first-order low-pass filter on the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging features. S62. When the phase change abruptness identification result in the charging scenario indicates that the target battery has reached the charging phase change abruptness point, control the charging current to reduce it in stages until it is reduced to the preset charging current threshold and then disconnect the charging main contactor. S63. When the phase transition abruptness identification result in the discharge scenario is that the target battery has not reached the discharge phase transition abruptness, jump to execute the step of performing a smooth voltage obtained by first-order low-pass filtering of the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging features. S64. When the phase transition abruptness identification result in the discharge scenario indicates that the target battery has reached the discharge phase transition abruptness point, the discharge current is controlled to be reduced in stages until it is reduced to the preset discharge current threshold, at which point the discharge main contactor is cut off.

[0071] In this embodiment of the invention, S61, when the phase transition abruptness identification result in the charging scenario determines that the target battery has not reached the charging phase transition abruptness point, it indicates that the current battery is still in the safe charging platform range where the positive and negative electrode phases coexist, the electrode active material is not depleted, there is no risk of structural instability, and there is no need to execute the cut-off protection. The process directly jumps to step 103 to perform first-order low-pass filtering on the real-time voltage to obtain a smooth voltage, and then combines the real-time current and the matched sliding window length to perform feature calculations and obtain the basic charging and discharging characteristics. The real-time feature calculation and phase transition abruptness monitoring are continuously cycled to complete the process; S62, when In the charging scenario, the phase transition abruptness point identification result indicates that when the target battery reaches the charging phase transition abruptness point, it signifies that both the positive and negative electrodes are about to enter the unstable single-phase solid solution stage. Continuing to charge will trigger irreversible side reactions such as electrolyte oxidation and lithium plating on the negative electrode. To avoid impacting the battery main circuit due to instantaneous high current cutoff and to achieve precise overcharge protection, the charging circuit is controlled to reduce the current in stages according to a preset gradient until the charging current drops to a preset charging current threshold. At this point, the charging main contactor is immediately disconnected, completely terminating the charging process. The charging staged current reduction follows a linear gradient current reduction rule, and the specific relationship is as follows:

[0072] In the formula, This is the real-time charging current after the nth level of regulation; For the first Real-time charging current after stage regulation; A preset single-stage charging current reduction gradient is provided; S63. When the phase transition abruptness identification result in the discharge scenario indicates that the target battery has not reached the discharge phase transition abruptness point, it means that the current battery is still in the safe discharge platform range, the electrode active material is not completely deintercalated, and there is no risk of lattice collapse. The process jumps to step 103, where a first-order low-pass filter is applied to the real-time voltage to obtain a smooth voltage, and feature calculations are performed using the real-time current and sliding window length to obtain the basic characteristics of charging and discharging. The cyclic monitoring state of real-time phase transition identification is maintained. S64. When the phase transition abruptness identification result in the discharge scenario indicates that the target battery has reached the discharge phase transition abruptness point, it signifies that the available lithium source for the graphite anode is about to be depleted, and the lithium iron phosphate cathode is about to enter the unstable single-phase region. Continuing to discharge will cause damage to the electrode structure and decomposition of the electrolyte. To avoid over-discharge damage and reduce circuit impact, the discharge circuit is controlled to reduce the current in stages according to a preset gradient until the discharge current drops to the preset discharge current threshold. At this point, the main discharge contactor is immediately disconnected, terminating the discharge process. The discharge staged current reduction also adopts a linear gradient rule, with the specific relationship being:

[0073] In the formula, This refers to the real-time discharge current after the nth stage of regulation. For the first Real-time discharge current after stage regulation; By pre-setting a single-stage discharge current reduction gradient and implementing a protection method of gradually reducing the current in stages before cutting off, it can effectively avoid the circuit impact caused by instantaneous power outages and complete the protection action before the battery electrode material becomes structurally unstable. This fundamentally solves the technical problems of overcharging, over-discharging, and unreasonable capacity utilization caused by traditional fixed voltage threshold control.

[0074] Graded current reduction is a gradual control method that slowly reduces the charging and discharging current according to a preset gradient, avoiding circuit impact caused by instantaneous current surges; the preset charging current threshold is the critical current value that triggers the circuit cut-off action in the charging protection process; the charging main contactor is the core switching device that controls the on / off of the battery charging circuit; the preset discharging current threshold is the critical current value that triggers the circuit cut-off action in the discharging protection process; the discharging main contactor is the core switching device that controls the on / off of the battery discharging circuit.

[0075] Please see Figure 2 The curve is divided into "lithium insertion" and "lithium removal" stages. A sudden voltage change occurs at the end of the discharge (the end of the lithium removal stage), marking the end of the two-phase coexistence region of the graphite anode and the entry into the single-phase lithium-deficient region. The available lithium source is about to be depleted. Please refer to [further details]. Figure 3 The voltage changes abruptly at both the beginning and end of the charge and discharge cycle, corresponding to the phase transition process of the lithium iron phosphate cathode from two-phase coexistence to a single-phase solid solution. Combined with the Gibbs phase law (F=C−P under isothermal and isobaric conditions), the degree of freedom F=2−1=1 when the voltage changes abruptly, indicating that the material changes from two-phase coexistence to a single-phase solid solution, which is an intrinsic signal that the plateau period of the electrode active material has ended. Continuing to charge and discharge will trigger side reactions, providing the core theoretical basis for the invention of "identifying the critical state of charge and discharge based on the phase transition abrupt point".

[0076] Please see Figure 4 The invention comprises six sub-graphs, divided into a charging group (A1-A3) and a discharging group (B1-B3). The charging sub-graphs (A1-A3) show charging curves at different temperatures (15℃~55℃) at rates of 0.2C, 0.5C, and 1C, respectively. Under all conditions, a clear voltage inflection point (abrupt point) appears in the high SOC range (the end of charging), and the position of the inflection point is unaffected by temperature or rate changes. The discharging sub-graphs (B1-B3) show discharging curves at different temperatures (15℃~55℃) at rates of 0.2C, 0.5C, and 1C, respectively. Under all conditions, a clear voltage inflection point (abrupt point) appears in the low SOC range (the end of discharging), also unaffected by operating conditions. Therefore, the charging and discharging curves at different temperatures and rates exhibit consistent voltage abrupt change characteristics, indicating that the phase transition abrupt change point identification method of this invention has extremely strong adaptability to operating conditions. It does not require parameter adjustments for complex environments and can accurately identify the intrinsic charging and discharging state of the battery, solving the problem of misjudgment caused by the traditional fixed voltage threshold method being easily affected by temperature and rate.

[0077] Please see Figure 5 It contains four curves, each corresponding to a different charge / discharge control scheme: 3.65V-2.5V cycle: Traditional fixed voltage control scheme, the capacity decays the fastest.

[0078] 2.5-3.60V cycling: A fixed voltage scheme with relaxed charging upper limit, but with a secondary decay rate.

[0079] 3.0V-3.50V Cycling: A fixed voltage scheme that further narrows the voltage range, resulting in reduced attenuation.

[0080] Dynamic voltage cycling: The control scheme of this invention, based on the identification of phase transition abrupt points, results in the slowest capacity decay.

[0081] After 1000 cycles, the capacity retention rate of the dynamic voltage cycling group was up to 15% higher than that of the traditional fixed voltage group (3.65V-2.5V), significantly outperforming all fixed voltage schemes. This demonstrates that the present invention can terminate charging and discharging in time before structural instability changes occur in the positive and negative electrode materials, effectively suppressing lattice collapse caused by overcharging and over-discharging, and substantially extending the battery cycle life, thus verifying the effectiveness and superiority of the invention in practical applications. Example

[0082] Please see Figure 6 The present invention provides a charge and discharge protection system for lithium iron phosphate graphite batteries based on phase transition abrupt change point identification, comprising: Data acquisition module 601 is used to acquire the historical overall SOH, real-time voltage, real-time current and charge transfer resistance of the target battery; The key value matching module 602 is used to perform key value matching using historical comprehensive SOH to obtain charge and discharge dynamic parameters, including single electrode duration, sliding window length, charging end voltage, discharging end voltage and voltage change rate threshold. The feature calculation module 603 is used to perform feature calculations on the smoothed voltage obtained by first-order low-pass filtering of the real-time voltage, and combine it with the real-time current and the sliding window length to obtain the basic charging and discharging features. The charging phase transition abrupt point identification module 604 is used to identify the phase transition abrupt point when the smoothing voltage is greater than the charging end voltage, by using the basic characteristics of charging and discharging, the duration of a single electrode, the voltage change rate threshold and the charge transfer resistance, and to obtain the phase transition abrupt point identification result in the charging scenario. The discharge phase transition abrupt point identification module 605 is used to identify the phase transition abrupt point by using the basic characteristics of charging and discharging, single electrode duration, voltage change rate threshold and charge transfer resistance when the smoothing voltage is less than the discharge end voltage, so as to obtain the phase transition abrupt point identification result in the discharge scenario. The protection operation module 606 is used to perform corresponding protection operations based on the phase transition abruptness identification results in the charging scenario and the phase transition abruptness identification results in the discharging scenario.

[0083] Since the above is a system corresponding to a method for protecting lithium iron phosphate graphite batteries based on phase transition abrupt point identification, its implementation principle is the same as that of a method for protecting lithium iron phosphate graphite batteries based on phase transition abrupt point identification. For the sake of convenience and brevity, those skilled in the art can clearly understand that the specific working process of the system and modules described above can be referred to the corresponding process in the aforementioned method embodiments, and will not be repeated here. Example

[0084] An electronic device according to an embodiment of the present invention includes: a memory and a processor, wherein the memory stores a computer program; when the computer program is executed by the processor, the processor performs a lithium iron phosphate graphite battery charging and discharging protection method based on phase transition abrupt point identification as described in any of the above embodiments.

[0085] The memory can be an electronic memory such as flash memory, EEPROM (Electrically Erasable Programmable Read-Only Memory), EPROM, hard disk, or ROM. The memory has storage space for program code used to perform any of the method steps described above. For example, the storage space for program code may include individual program codes for implementing the various steps in the methods described above. This program code can be read from or written to one or more computer program products. These computer program products include program code carriers such as hard disks, compact discs (CDs), memory cards, or floppy disks. The program code may be compressed, for example, in a suitable form. When run by a computing processing device, this code causes the computing processing device to perform the various steps in the methods described above. Example

[0086] This invention provides a computer-readable storage medium storing a computer program thereon. When the computer program is executed, it implements the charging and discharging protection method for lithium iron phosphate graphite batteries based on phase transition abrupt point identification as described in any of the above embodiments.

[0087] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0088] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0089] 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 units can be selected to achieve the purpose of this embodiment according to actual needs.

[0090] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0091] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for charge and discharge protection of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification, characterized in that, include: Obtain the historical total state of health (SOH), real-time voltage, real-time current, and charge transfer resistance of the target battery; The historical comprehensive SOH is used for key value matching to obtain charge and discharge dynamic parameters, which include single electrode duration, sliding window length, charging end voltage, discharging end voltage and voltage change rate threshold. The smoothed voltage obtained by performing a first-order low-pass filter on the real-time voltage is combined with the real-time current and the sliding window length to perform feature calculations, thereby obtaining the basic charging and discharging characteristics. When the smooth voltage is greater than the charging end voltage, the phase transition abrupt point is identified using the basic charging and discharging characteristics, the single electrode duration, the voltage change rate threshold, and the charge transfer resistance to obtain the phase transition abrupt point identification result in the charging scenario. When the smoothing voltage is less than the discharge end voltage, the phase transition abrupt point is identified using the basic charging and discharging characteristics, the single electrode duration, the voltage change rate threshold, and the charge transfer resistance to obtain the phase transition abrupt point identification result in the discharge scenario. The corresponding protection operation is executed based on the phase transition abruptness identification result in the charging scenario, and the corresponding protection operation is executed based on the phase transition abruptness identification result in the discharging scenario.

2. The method for charge and discharge protection of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification according to claim 1, characterized in that, The process of using the historical comprehensive SOH for key value matching to obtain charge / discharge dynamic parameters includes: The search key is constructed using the historical comprehensive SOH. The preset dynamic parameter table is retrieved using the search key, and the charging and discharging dynamic parameters are obtained by matching.

3. The method for charge and discharge protection of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification according to claim 1, characterized in that, The smoothed voltage obtained by performing a first-order low-pass filter on the real-time voltage, combined with the real-time current and the sliding window length, is used to perform feature calculations to obtain the basic charging and discharging characteristics, including: The real-time voltage is subjected to a first-order low-pass filter to obtain a smoothed voltage; The instantaneous voltage change rate at the current moment is determined by using the smoothed voltage and the smoothed voltage at the previous moment. Obtain multiple historical instantaneous voltage change rates within the length of the sliding window; The average of the instantaneous voltage change rate at the current moment and the multiple historical instantaneous voltage change rates is used to obtain the average target change rate at the current moment; The differential capacity at the current moment is determined using the smoothed voltage, the smoothed voltage at the previous moment, and the real-time current. The basic charging and discharging characteristics include the instantaneous voltage change rate, the target change rate mean, and the differential capacity.

4. The method for charge and discharge protection of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification according to claim 3, characterized in that, When the smoothed voltage is greater than the charging end voltage, the phase transition abruptness point is identified using the basic charging and discharging characteristics, the single electrode duration, the voltage change rate threshold, and the charge transfer resistance, to obtain the phase transition abruptness point identification result in the charging scenario, including: When the smooth voltage is greater than the charging end voltage, the instantaneous voltage change rate and the differential capacity are weighted together with a preset positive electrode coupling factor to obtain the lithium iron phosphate positive electrode phase change composition in the charging scenario. When the phase change of the lithium iron phosphate cathode, the instantaneous voltage change rate, and the average of the target change rate meet the preset first cathode triggering condition, the cathode triggering time is recorded. When the phase change of the lithium iron phosphate cathode, the average of the instantaneous voltage change rate and the target change rate do not meet the preset first cathode trigger condition, the process jumps to the step of performing the smoothed voltage obtained by first-order low-pass filtering on the real-time voltage, and performing feature calculations in combination with the real-time current and the sliding window length to obtain the basic charging and discharging characteristics. The preset first positive electrode triggering condition is specifically that the phase change fraction of the lithium iron phosphate positive electrode is greater than or equal to the preset feature score threshold, the instantaneous voltage change rate is greater than or equal to the voltage change rate threshold, and the average target change rate is greater than or equal to the voltage change rate threshold, and the duration for which all three conditions are met is greater than or equal to the single electrode duration. The charge transfer resistor is used as the graphite negative electrode phase change component in the charging scenario; When the phase change of the graphite negative electrode meets the preset first negative electrode triggering condition, the negative electrode triggering time is recorded; When the phase change of the graphite negative electrode does not meet the preset first negative electrode triggering condition, the process jumps to the step of performing the smoothed voltage obtained by first-order low-pass filtering on the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging characteristics. The preset first negative electrode triggering condition is specifically that the phase change fraction of the graphite negative electrode is greater than or equal to the preset feature score threshold, and the duration is greater than or equal to the single electrode duration; When the positive electrode trigger time and the negative electrode trigger time meet the preset first charging phase transition abrupt change point identification condition, it is determined that the target battery has reached the charging phase transition abrupt change point. When the positive electrode trigger time and the negative electrode trigger time do not meet the preset first charging phase transition abrupt change point identification condition, it is determined that the target battery has not reached the charging phase transition abrupt change point. The preset first charging phase transition abrupt change point identification condition is specifically that the positive electrode trigger time is less than the negative electrode trigger time, and the difference between the positive electrode trigger time and the negative electrode trigger time is within the preset positive electrode trigger time range.

5. The method for charge and discharge protection of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification according to claim 3, characterized in that, When the smoothing voltage is less than the discharge terminal voltage, the phase transition abruptness point is identified using the basic charge / discharge characteristics, the single electrode duration, the voltage change rate threshold, and the charge transfer resistance to obtain the phase transition abruptness point identification result under the discharge scenario, including: When the smoothing voltage is less than the discharge terminal voltage, the charge transfer resistor is used as the graphite negative electrode phase transition component in the discharge scenario; When the phase change of the graphite negative electrode, the absolute value of the instantaneous voltage change rate, and the absolute value of the average target change rate satisfy the preset second negative electrode triggering condition, the negative electrode triggering time is recorded. When the phase change of the graphite negative electrode, the absolute value of the instantaneous voltage change rate, and the absolute value of the average target change rate do not meet the preset second negative electrode triggering condition, the process jumps to the step of performing the smoothed voltage obtained by performing first-order low-pass filtering on the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging characteristics. The preset second negative electrode triggering condition is specifically that the phase change fraction of the graphite negative electrode is greater than or equal to the preset feature score threshold, the absolute value of the instantaneous voltage change rate is greater than or equal to the voltage change rate threshold, and the absolute value of the average target change rate is greater than or equal to the voltage change rate threshold, and the duration for which the three conditions are simultaneously satisfied is greater than or equal to the duration of the single electrode. The absolute value of the instantaneous voltage change rate and the differential capacity are weighted together with a preset positive electrode coupling factor to obtain the phase change composition of the lithium iron phosphate positive electrode under the discharge scenario; When the phase change of the lithium iron phosphate cathode meets the preset second cathode trigger condition, the cathode trigger time is recorded; When the phase change of the lithium iron phosphate cathode does not meet the preset second cathode trigger condition, the process jumps to the step of performing the smoothed voltage obtained by first-order low-pass filtering of the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging characteristics. The preset second positive electrode triggering condition is specifically that the phase change fraction of the lithium iron phosphate positive electrode is greater than or equal to the preset feature score threshold, and the duration is greater than or equal to the single electrode duration; When the positive electrode trigger time and the negative electrode trigger time meet the preset second discharge phase transition abrupt change point identification condition, it is determined that the target battery has reached the discharge phase transition abrupt change point. If the positive electrode trigger time and the negative electrode trigger time do not meet the preset second discharge phase transition abrupt change point identification condition, then it is determined that the target battery has not reached the discharge phase transition abrupt change point. The preset second discharge phase transition abrupt change point identification condition is specifically that the negative electrode trigger time is less than the positive electrode trigger time, and the difference between the positive electrode trigger time and the negative electrode trigger time is within the preset negative electrode trigger time range.

6. The method for charge and discharge protection of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification according to claim 1, characterized in that, The step of performing corresponding protection operations based on the phase transition abruptness identification results in the charging scenario, and performing corresponding protection operations based on the phase transition abruptness identification results in the discharging scenario, includes: When the phase transition abruptness identification result in the charging scenario indicates that the target battery has not reached the charging phase transition abruptness, the process jumps to the step of performing the smoothed voltage obtained by performing first-order low-pass filtering on the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging features. When the phase transition abruptness identification result in the charging scenario indicates that the target battery has reached the charging phase transition abruptness point, the charging current is controlled to be reduced in stages until it is reduced to a preset charging current threshold, at which point the main charging contactor is disconnected. When the phase transition abruptness identification result in the discharge scenario indicates that the target battery has not reached the discharge phase transition abruptness, the process jumps to the step of performing the smoothed voltage obtained by first-order low-pass filtering on the real-time voltage, and combining the real-time current and the sliding window length to perform feature calculations to obtain the basic charging and discharging features. When the phase transition abruptness identification result in the discharge scenario indicates that the target battery has reached the discharge phase transition abruptness point, the discharge current is controlled to be reduced in stages until it is reduced to a preset discharge current threshold, at which point the discharge main contactor is cut off.

7. The method for charge and discharge protection of lithium iron phosphate graphite batteries based on phase transition abrupt change point identification according to any one of claims 1-6, characterized in that, The acquisition of the historical total SOH of the target battery includes: Obtain the charging and discharging transient capacities of the target battery; The ratio of the sudden charging capacity to the preset charging reference capacity is converted into a percentage to obtain the charging SOH; The ratio of the discharge mutation capacity to the preset discharge reference capacity is converted into a percentage to obtain the discharge SOH; The sum of the charging SOH and the discharging SOH is calculated, and the average of the sum is calculated to obtain the historical comprehensive SOH.

8. A charge / discharge protection system for lithium iron phosphate graphite batteries based on phase transition abrupt change point identification, characterized in that, include: The data acquisition module is used to acquire the historical overall SOH, real-time voltage, real-time current, and charge transfer resistance of the target battery; The key value matching module is used to perform key value matching using the historical comprehensive SOH to obtain charge and discharge dynamic parameters, which include single electrode duration, sliding window length, charging end voltage, discharging end voltage and voltage change rate threshold. The feature calculation module is used to perform feature calculations on the smoothed voltage obtained by first-order low-pass filtering of the real-time voltage, and combine it with the real-time current and the sliding window length to obtain the basic charging and discharging features. The charging phase transition abrupt point identification module is used to identify the phase transition abrupt point by using the basic charging and discharging characteristics, the single electrode duration, the voltage change rate threshold, and the charge transfer resistance when the smooth voltage is greater than the charging end voltage, so as to obtain the phase transition abrupt point identification result in the charging scenario. The discharge phase transition abrupt point identification module is used to identify the phase transition abrupt point by using the basic charging and discharging characteristics, the single electrode duration, the voltage change rate threshold, and the charge transfer resistance when the smoothing voltage is less than the discharge end voltage, so as to obtain the phase transition abrupt point identification result in the discharge scenario. The protection operation module is used to perform corresponding protection operations based on the phase transition abruptness identification results in the charging scenario and to perform corresponding protection operations based on the phase transition abruptness identification results in the discharging scenario.

9. An electronic device, characterized in that, It includes a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and executed as described in any one of claims 1 to 7, which is a method for protecting lithium iron phosphate graphite batteries by charging and discharging based on phase transition abrupt point identification.

10. A computer-readable storage medium, characterized in that, The system contains a computer program that can be loaded by a processor and executed as described in any one of claims 1 to 7, for the charge and discharge protection method of lithium iron phosphate graphite batteries based on phase transition abrupt point identification.

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