A lithium battery safe charging control method, system, product and medium

Abstract

A lithium battery safe charging control method, system, product and medium, relating to the field of charging control, the method comprising: in response to a charging request, applying a detection pulse to collect voltage data, calculating ohmic resistance and polarization resistance. When the polarization resistance is not greater than a threshold value, the total internal resistance of the battery is calculated and the initial charging current is determined to perform constant current charging. At the same time, the protection temperature threshold is dynamically set according to the total internal resistance and the ambient temperature. During the charging process, the state is evaluated periodically: the total internal resistance is recalculated by applying a current disturbance, the internal resistance change rate is calculated, and the comprehensive score is obtained by weighted fusion of the temperature rise rate and the voltage change rate. The charging current is adjusted according to the score, and the adjustment amplitude is constrained by the current total internal resistance, and the temperature threshold is updated according to the adjusted current and total internal resistance. The method realizes dynamic optimization of charging current and adaptive adjustment of temperature protection through multi-parameter fusion. The implementation of the present application improves the balance between safety and charging efficiency during the charging process of the lithium battery.

Description

Technical Field

[0001] This application relates to the field of charging control, and in particular to a method, system, product, and medium for safe charging control of lithium batteries. Background Technology

[0002] With the rapid development of electric vehicles, energy storage systems, and portable electronic devices, lithium batteries have been widely used as a primary energy storage device. The charging process of lithium batteries directly affects their lifespan, safety performance, and energy utilization efficiency. Therefore, achieving safe and efficient charging of lithium batteries has always been a key focus in the industry.

[0003] In existing technologies, conventional lithium battery charging control methods mainly employ a constant current-constant voltage charging strategy. This method charges the battery with a constant current in the initial stage of charging, and then switches to a constant voltage charging stage once the battery voltage reaches a set charging cutoff voltage. During charging, the control system sets fixed temperature and voltage protection thresholds. When the battery temperature or voltage exceeds the preset thresholds, a protection mechanism is triggered to reduce the charging current or stop charging.

[0004] However, existing fixed threshold protection strategies have limitations. The internal resistance of lithium batteries changes dynamically with factors such as charging status, temperature, and aging, and a fixed charging current and protection threshold cannot adapt to changes in the battery's real-time state. In low-temperature environments, increased battery internal resistance leads to increased heat generation, and a fixed temperature threshold may not trigger protection in time; in high-temperature environments, a fixed threshold limits charging efficiency. This static control method struggles to balance safety and charging efficiency under different operating conditions. Summary of the Invention

[0005] This application provides a lithium battery safe charging control method, system, product, and medium to improve the balance between safety and charging efficiency during lithium battery charging.

[0006] In a first aspect, this application provides a lithium battery safe charging control method, applied to a lithium battery safe charging control system. The method includes: responding to a charging request by applying a detection current pulse of preset amplitude to a target lithium battery; acquiring voltage response data; calculating the ohmic internal resistance and polarization internal resistance of the target lithium battery based on the voltage response data; when the polarization internal resistance does not exceed a preset polarization internal resistance threshold, calculating the total internal resistance of the battery based on the ohmic internal resistance and polarization internal resistance; determining the initial charging current based on the total internal resistance of the battery; and performing constant current charging on the target lithium battery using the initial charging current; acquiring the current ambient temperature; and adjusting the battery's total internal resistance based on the current ambient temperature. The system dynamically sets a protection temperature threshold. During constant current charging, it performs a charging status assessment according to a preset evaluation cycle, calculates the rate of change of the current total internal resistance of the battery relative to the previous evaluation cycle, and weights and fuses the rate of change of internal resistance, the current temperature rise rate of the target lithium battery, and the current charging voltage change rate to obtain a comprehensive score. This charging status assessment includes applying a current perturbation to the target lithium battery to recalculate the current total internal resistance of the battery. The system adjusts the current charging current based on the comprehensive score and constrains the adjustment range of the current charging current based on the current total internal resistance of the battery. The protection temperature threshold is updated based on the adjusted charging current and the current total internal resistance of the battery.

[0007] In the above embodiments, the ohmic internal resistance and polarization internal resistance are calculated by applying a probe current pulse. Based on the total battery internal resistance, the initial charging current is determined and constant current charging is performed. During charging, the system applies current perturbation according to a preset evaluation cycle to recalculate the current total battery internal resistance. The rate of change of internal resistance is calculated and weighted with the current temperature rise rate and the charging voltage change rate to obtain a comprehensive score. When adjusting the charging current according to the comprehensive score, the system uses the current total battery internal resistance to constrain the adjustment range and updates the protection temperature threshold based on the adjusted charging current and the current total battery internal resistance, thus achieving dynamic adaptation of charging parameters to the real-time battery state.

[0008] In conjunction with some embodiments of the first aspect, in some embodiments, the step of obtaining the current ambient temperature and dynamically setting the protection temperature threshold based on the total internal resistance of the battery and the current ambient temperature specifically includes: obtaining the current ambient temperature of the target lithium battery; calculating the theoretical heat generation power based on the total internal resistance of the battery and the current charging current, and calculating the theoretical temperature rise value based on a preset thermal resistance coefficient; calculating the ratio of the total internal resistance of the battery to a preset internal resistance reference value as an internal resistance growth factor, calculating a temperature correction coefficient through a nonlinear decay function, wherein the temperature correction coefficient decreases nonlinearly with the internal resistance growth factor; and determining the protection temperature threshold based on the current ambient temperature, the theoretical temperature rise value, and the temperature correction coefficient.

[0009] In the above embodiments, after obtaining the current ambient temperature, the theoretical heat generation power is calculated based on the total battery internal resistance and the current charging current, and the theoretical temperature rise is calculated based on the thermal resistance coefficient. The system calculates the ratio of the total battery internal resistance to a preset internal resistance benchmark value as the internal resistance growth factor, and calculates the temperature correction coefficient through a nonlinear decay function. This temperature correction coefficient decreases nonlinearly with the internal resistance growth factor, thereby lowering the protection temperature threshold when the battery internal resistance increases and raising the protection temperature threshold when the battery internal resistance is normal, realizing the dynamic adjustment of the protection temperature threshold according to the battery internal resistance state and the ambient temperature.

[0010] In conjunction with some embodiments of the first aspect, in some embodiments, the step of performing a charging state assessment according to a preset assessment cycle during constant current charging, calculating the rate of change of the current total internal resistance of the battery relative to the previous assessment cycle, and weighting and fusing the rate of change of internal resistance, the current temperature rise rate of the target lithium battery, and the current charging voltage change rate to obtain a comprehensive score, specifically includes: during constant current charging, monitoring the stability of the current charging current according to a preset assessment cycle; when the current charging current meets a preset stability condition, applying a current disturbance to the target lithium battery and measuring the current total internal resistance of the battery; calculating the rate of change of the current total internal resistance of the battery relative to the previous assessment cycle; obtaining the current temperature rise rate and the current charging voltage change rate of the target lithium battery; dynamically adjusting the weighting coefficients according to the ratio of the rate of change of internal resistance to the current temperature rise rate; increasing the weighting coefficient of the current temperature rise rate when the rate of change of internal resistance exceeds a preset threshold; weighting and fusing the rate of change of internal resistance, the current temperature rise rate, and the current charging voltage change rate to obtain a current comprehensive score; and accumulating the current comprehensive score over time to obtain a cumulative risk score, using the cumulative risk score as the comprehensive score.

[0011] In the above embodiments, during constant current charging, the stability of the current charging current is monitored according to a preset evaluation cycle. When the stability condition is met, a current perturbation is applied and the current total internal resistance of the battery is measured. The system calculates the rate of change of the current total internal resistance of the battery relative to the previous evaluation cycle, and obtains the current temperature rise rate and the current charging voltage change rate. The system dynamically adjusts the weighting coefficients based on the ratio of the internal resistance change rate to the current temperature rise rate. When the internal resistance change rate exceeds a preset threshold, the weighting coefficient of the current temperature rise rate is increased, and the current comprehensive score is time-weighted and accumulated to obtain a cumulative risk score, thus realizing a multi-dimensional comprehensive evaluation of the charging state.

[0012] In conjunction with some embodiments of the first aspect, in some embodiments, the step of adjusting the current charging current based on a comprehensive score, constraining the adjustment range of the current charging current based on the current total internal resistance of the battery, and updating the protection temperature threshold based on the adjusted charging current and the current total internal resistance of the battery specifically includes: determining the charging current adjustment amount based on the comprehensive score; determining the maximum allowable adjustment range based on the internal resistance growth factor of the current total internal resistance relative to a preset internal resistance benchmark value; calculating the change in charging power based on the adjusted charging current; estimating the current heat dissipation capacity based on the current temperature rise rate; constraining the charging current adjustment amount within the maximum allowable adjustment range and the power upper limit corresponding to the current heat dissipation capacity to obtain the actual adjustment amount; adjusting the current charging current based on the actual adjustment amount; calculating the adjusted theoretical heat dissipation power based on the adjusted charging current and the current total internal resistance of the battery; and updating the protection temperature threshold based on the theoretical heat dissipation power and the current ambient temperature.

[0013] In the above embodiments, the charging current adjustment amount is determined based on a comprehensive score, and the maximum allowable adjustment range is determined based on the internal resistance growth factor of the current total battery internal resistance relative to a preset internal resistance benchmark. The system calculates the change in charging power based on the adjusted charging current, estimates the current heat dissipation capacity based on the current temperature rise rate, and constrains the charging current adjustment amount within the maximum allowable adjustment range and the power upper limit corresponding to the current heat dissipation capacity. After adjusting the current charging current according to the actual adjustment amount, the system calculates the adjusted theoretical heat generation power based on the adjusted charging current and the current total battery internal resistance, and updates the protection temperature threshold, thus achieving a safety constraint on the charging current adjustment.

[0014] In conjunction with some embodiments of the first aspect, in some embodiments, after updating the protection temperature threshold based on the adjusted charging current and the current total internal resistance of the battery, the method further includes: calculating the current ohmic internal resistance and the current polarization internal resistance by applying a current perturbation to the target lithium battery, calculating the polarization growth rate of the current polarization internal resistance over multiple consecutive evaluation periods, and calculating the ohmic growth rate of the current ohmic internal resistance; calculating the growth rate dispersion between the polarization growth rate and the ohmic growth rate; when the growth rate dispersion exceeds a preset dispersion threshold, switching constant current charging to a constant voltage charging mode with the current charging voltage as the upper limit; continuing to monitor the current polarization internal resistance according to a preset evaluation period in the constant voltage charging mode, and resuming constant current charging when the current polarization internal resistance falls below a preset polarization internal resistance threshold.

[0015] In the above embodiments, the current ohmic internal resistance and the current polarization internal resistance are calculated separately by applying current perturbation, and the polarization growth rate of the current polarization internal resistance and the ohmic growth rate of the current ohmic internal resistance are calculated over multiple consecutive evaluation cycles. The system calculates the growth rate dispersion between the polarization growth rate and the ohmic growth rate. When the growth rate dispersion exceeds a preset dispersion threshold, the constant current charging is switched to a constant voltage charging mode with the current charging voltage as the upper limit. In the constant voltage charging mode, the current polarization internal resistance continues to be monitored. When the current polarization internal resistance falls below the preset polarization internal resistance threshold, constant current charging is resumed, thus realizing dynamic switching of the charging mode.

[0016] In conjunction with some embodiments of the first aspect, in some embodiments, after updating the protection temperature threshold based on the adjusted charging current and the current total internal resistance of the battery, the method further includes: when the comprehensive score is in a preset warning range for multiple consecutive evaluation cycles, pausing constant current charging and entering a resting phase; during the resting phase, acquiring the terminal voltage change of the target lithium battery, obtaining the transient voltage drop component and the gradually changing voltage fall component in the terminal voltage change, wherein the transient voltage drop component corresponds to the voltage released by the ohmic internal resistance, and the gradually changing voltage fall component corresponds to the voltage released by the polarization effect relaxation; calculating the polarization relaxation ratio of the gradually changing voltage fall component relative to the transient voltage drop component; determining the recovery charging current based on the polarization relaxation ratio, re-performing constant current charging on the target lithium battery with the recovery charging current, and resetting the protection temperature threshold based on the recovery charging current and the current total internal resistance of the battery.

[0017] In the above embodiment, constant current charging is paused and a resting phase is initiated when the comprehensive score remains within a preset warning range for multiple consecutive evaluation cycles. During the resting phase, the system collects the terminal voltage changes of the target lithium battery, acquiring the transient voltage drop component and the gradually changing voltage recovery component within the terminal voltage changes. The system calculates the polarization relaxation ratio of the gradually changing voltage recovery component relative to the transient voltage drop component, and determines the recovery charging current based on the polarization relaxation ratio. The system then re-executes constant current charging with the recovery charging current and resets the protection temperature threshold based on the recovery charging current and the current total internal resistance of the battery, thus achieving charging recovery control based on polarization relaxation characteristics.

[0018] In conjunction with some embodiments of the first aspect, in some embodiments, after updating the protection temperature threshold based on the adjusted charging current and the current total internal resistance of the battery, the method further includes: when the battery temperature has not reached the protection temperature threshold, continuing constant current charging and entering the next evaluation cycle until the battery temperature reaches the protection temperature threshold and charging is stopped.

[0019] In the above embodiments, after updating the protection temperature threshold based on the adjusted charging current and the current total internal resistance of the battery, it is determined whether the battery temperature has reached the protection temperature threshold. When the battery temperature has not reached the protection temperature threshold, the system continues to perform constant current charging and enters the next evaluation cycle, continuously monitoring the battery status and dynamically adjusting the charging parameters during the charging process. When the battery temperature reaches the protection temperature threshold, the system stops charging to avoid safety risks caused by excessive battery temperature, thus realizing charging termination control based on dynamic temperature threshold.

[0020] In a second aspect, embodiments of this application provide a lithium battery safe charging control system, which includes: one or more processors and a memory; the memory is coupled to the one or more processors, and the memory is used to store computer program code, the computer program code including computer instructions, and the one or more processors call the computer instructions to cause the lithium battery safe charging control system to perform the method described in the first aspect and any possible implementation thereof.

[0021] Thirdly, embodiments of this application provide a computer-readable storage medium including instructions that, when executed on a lithium battery safe charging control system, cause the lithium battery safe charging control system to perform the method described in the first aspect and any possible implementation thereof.

[0022] Fourthly, embodiments of this application provide a computer program product containing instructions that, when the computer program product is run on a lithium battery safety charging control system, cause the lithium battery safety charging control system to perform the method described in the first aspect and any possible implementation thereof.

[0023] Understandably, the lithium battery safety charging control system provided in the second aspect, the computer storage medium provided in the third aspect, and the computer program product provided in the fourth aspect are all used to execute the methods provided in the embodiments of this application. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods, and will not be repeated here.

[0024] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0025] 1. By employing a method that responds to charging requests by applying a probe current pulse to calculate the ohmic and polarization internal resistances, determines the initial charging current based on the total battery internal resistance, and performs constant current charging, and applies current disturbances according to a preset evaluation cycle during charging to recalculate the current total battery internal resistance, calculating the rate of change of internal resistance and weighting it with the current temperature rise rate and charging voltage change rate to obtain a comprehensive score, adjusting the current charging current based on the comprehensive score and constraining the adjustment range using the current total battery internal resistance, and updating the protection temperature threshold based on the adjusted charging current and the current total battery internal resistance, this method effectively solves the problem in existing technologies where fixed charging currents and fixed protection thresholds cannot adapt to real-time changes in battery status and are difficult to balance charging safety and charging efficiency. This enables dynamic adjustment of charging parameters and protection thresholds based on the real-time internal resistance state of the battery.

[0026] 2. By acquiring the current ambient temperature, calculating the theoretical heat generation power based on the total battery internal resistance and the current charging current, and calculating the theoretical temperature rise based on the thermal resistance coefficient, the ratio of the total battery internal resistance to the preset internal resistance benchmark value is calculated as the internal resistance growth factor. The temperature correction coefficient is calculated through a nonlinear decay function, and this temperature correction coefficient decreases nonlinearly with the internal resistance growth factor. The protection temperature threshold is determined based on the current ambient temperature, the theoretical temperature rise value, and the temperature correction coefficient. This effectively solves the problem of large differences in protection effect of fixed temperature protection threshold under different ambient temperatures and battery internal resistance states in the existing technology, and thus realizes the dynamic setting of the protection temperature threshold according to the ambient temperature and battery internal resistance state.

[0027] 3. By employing a method that monitors the stability of the current charging current during constant current charging at preset evaluation cycles, applies current disturbances and measures the current total internal resistance of the battery when stability conditions are met, calculates the rate of change of the current total internal resistance relative to the previous evaluation cycle, obtains the current temperature rise rate and the current charging voltage change rate, dynamically adjusts the weighting coefficients based on the ratio of the internal resistance change rate to the current temperature rise rate, and increases the weighting coefficient of the current temperature rise rate when the internal resistance change rate exceeds a preset threshold, and weights and fuses the internal resistance change rate, the current temperature rise rate, and the current charging voltage change rate to obtain the current comprehensive score, and then performs time-weighted accumulation of the current comprehensive score to obtain the cumulative risk score, this method effectively solves the problem of insufficient accuracy in evaluating the charging state using a single parameter in existing technologies, thereby realizing a comprehensive evaluation of the charging state based on multi-dimensional parameter fusion. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating a lithium battery safe charging control method in an embodiment of this application.

[0029] Figure 2 This is another schematic flowchart of the lithium battery safe charging control method in the embodiments of this application;

[0030] Figure 3 This is a schematic diagram of the physical device structure of a lithium battery safe charging control system in the embodiments of this application. Detailed Implementation

[0031] The terminology used in the following embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification of this application, the singular expressions “a,” “an,” “the,” “the,” and “this” are intended to include the plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this application refers to any or all possible combinations including one or more of the listed items.

[0032] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0033] For ease of understanding, the method provided in this implementation is described in process below. Please refer to [link / reference]. Figure 1 This is a flowchart illustrating a lithium battery safe charging control method in an embodiment of this application.

[0034] S101. In response to a charging request, a detection current pulse of preset amplitude is applied to the target lithium battery, voltage response data is collected, and the ohmic internal resistance and polarization internal resistance of the target lithium battery are calculated based on the voltage response data.

[0035] The charging request is a trigger signal that initiates the lithium battery charging process. This signal can be initiated by user operation, system scheduling, or automatically by the battery management system. The probe current pulse is a square wave current signal with a preset amplitude and duration. This pulse is used to excite the battery to generate a voltage response to extract the battery's internal resistance parameters. Voltage response data refers to the numerical sequence of battery terminal voltage changes over time, collected during and after the application of the probe current pulse. Ohmic internal resistance represents the instantaneous impedance generated by the battery's internal electrode materials, electrolyte, and connecting components to the passage of current. This impedance causes a transient voltage drop at the moment the current is switched on. Polarization internal resistance represents the impedance caused by concentration polarization and electrochemical polarization during the electrochemical reaction process inside the battery. This impedance causes the voltage response to exhibit a time-delay characteristic.

[0036] Specifically, upon receiving a charging request, the lithium battery safety charging control system controls the charging circuit to apply a probe current pulse of preset amplitude to the target lithium battery. The amplitude of this probe current pulse is set to 0.1C to 0.3C of the battery's rated capacity, and the pulse duration is set to 100 to 500 milliseconds. The system acquires battery terminal voltage data at a sampling frequency of no less than 1000Hz to obtain a complete voltage response data sequence. The system performs time-domain analysis on the voltage response data, decomposing the voltage response curve into transient response components and delayed response components. The transient response component corresponds to the voltage jump at the moment the current is applied; the ohmic internal resistance is obtained by calculating the ratio of the voltage difference to the current amplitude. The delayed response component corresponds to the slow voltage change process; the polarization internal resistance is obtained by fitting the voltage delay response curve and combining it with the equivalent circuit model parameter identification method.

[0037] In some embodiments, the internal resistance parameter can be calculated in several ways: Optionally, the system is configured with a sampling frequency of 2000Hz, a square wave current pulse with an amplitude of 0.2C is applied to the battery for 300 milliseconds, the voltage time series is collected and high-frequency noise is filtered out, the ratio of the voltage change to the current amplitude within 10 milliseconds after the current is turned on is calculated to obtain the ohmic internal resistance, the voltage change curve within the time period from 10 milliseconds to 300 milliseconds is fitted with an exponential function, and the steady-state gain parameter of the fitted function is extracted as the polarization internal resistance; Optionally, the system adopts the electrochemical impedance spectroscopy analysis method, superimposes a small-amplitude AC current signal in the frequency range of 0.01Hz to 1000Hz onto the battery, synchronously collects the amplitude response and phase response of the battery terminal voltage at each frequency, constructs a frequency domain impedance characteristic curve, fits the equivalent circuit model to the frequency domain impedance data, and identifies the series resistance parameter in the equivalent circuit as the ohmic internal resistance and the parallel RC network resistance parameter as the polarization internal resistance by the least squares method. It is understandable that other signal excitation and parameter identification methods can also be used to achieve the separate calculation of ohmic internal resistance and polarization internal resistance, which is not limited here.

[0038] S102. When the polarization internal resistance does not exceed the preset polarization internal resistance threshold, calculate the total internal resistance of the battery based on the ohmic internal resistance and the polarization internal resistance, determine the initial charging current based on the total internal resistance of the battery, and perform constant current charging on the target lithium battery with the initial charging current.

[0039] The preset polarization resistance threshold refers to the safe upper limit of polarization resistance pre-set by the system based on the battery type and health status. When the measured polarization resistance exceeds this threshold, it indicates that the battery polarization effect is too strong and is not suitable for regular charging. The total battery internal resistance represents the sum of the battery's ohmic internal resistance and polarization internal resistance; this parameter comprehensively reflects the battery's overall impedance characteristics to current flow. The initial charging current refers to the charging current applied to the target lithium battery at the beginning of the constant current charging phase. Constant current charging refers to a charging mode that maintains a constant charging current throughout the charging process.

[0040] Specifically, the system compares the measured polarization resistance value with a preset polarization resistance threshold, which is typically set to 1.5 to 2 times the battery's nominal polarization resistance. When the polarization resistance does not exceed the threshold, the system sums the ohmic resistance and the polarization resistance to obtain the total battery internal resistance. The system calculates the power constraint current based on the battery's maximum allowable charging power and the current battery voltage, and the internal resistance constraint current based on the total battery internal resistance and the maximum allowable voltage drop. The smaller of the two values ​​is then multiplied by a safety factor of 0.8 to 0.9 to obtain the initial charging current. The system controls the charging circuit to perform constant current charging on the target lithium battery using this initial charging current. During constant current charging, the charging current remains constant, and the battery terminal voltage gradually increases as the battery's state of charge increases.

[0041] In some embodiments, the initial charging current can be determined in several ways: Optionally, the system reads a preset polarization internal resistance threshold and compares it with the measured polarization internal resistance. When the polarization internal resistance does not exceed the threshold, the total internal resistance of the battery is calculated. The maximum charging power and the current battery voltage are read to calculate the power constraint current. The maximum internal resistance voltage drop is set to 1 volt to calculate the internal resistance constraint current. The smaller of the two values ​​is selected and multiplied by a safety factor of 0.85 to obtain the initial charging current. A constant current charging command is sent to the charging control module, and the current parameter is transmitted. Optionally, the system uses a lookup table method to find adjacent data points in a pre-stored internal resistance-current correspondence table based on the measured total internal resistance of the battery. Linear interpolation is performed on the lookup table data to obtain a recommended charging current. This recommended charging current is used as the initial charging current to configure the charging circuit to output in constant current mode. It is understood that other charging current optimization algorithms based on internal resistance parameters can also be used to determine the initial charging current, which are not limited here.

[0042] S103. Obtain the current ambient temperature and dynamically set the protection temperature threshold based on the total internal resistance of the battery and the current ambient temperature.

[0043] The current ambient temperature refers to the real-time temperature of the space where the lithium battery is located, acquired by an independently placed ambient temperature sensor, and serves as the starting point for calculating the battery temperature rise. The total internal resistance of the battery is the sum of its ohmic internal resistance and polarization internal resistance, reflecting the overall impedance characteristics of the battery to the charging current. This parameter increases with battery aging. The theoretical heat generation power refers to the Joule heat power generated by the battery's internal resistance under the current charging current conditions, calculated using the formula P = I^2 × R_total, where I is the charging current and R_total is the total internal resistance of the battery. The thermal resistance coefficient refers to the thermal impedance parameter conducted from the battery's interior to the external environment, measured in degrees Celsius per watt, with a typical range of 3 to 15 degrees Celsius per watt. This parameter depends on the battery packaging, heat dissipation structure, and installation conditions. The theoretical temperature rise refers to the temperature rise caused by the theoretical heat generation power being conducted to the environment through the thermal resistance coefficient under steady-state conditions, calculated using the formula ΔT_theory = P × R_th, where R_th is the thermal resistance coefficient. The internal resistance growth factor refers to the ratio of the current total internal resistance of the battery to the preset internal resistance benchmark value, calculated according to the formula α = R_total / R_ref, where R_ref is the nominal total internal resistance of a healthy, fresh battery. The temperature correction coefficient refers to the temperature adjustment factor calculated based on the internal resistance growth factor using a nonlinear decay function, calculated according to the formula β = exp(-k × (α - 1)), where k is the decay coefficient, which decreases as the internal resistance growth factor increases. The protection temperature threshold refers to the highest safe upper limit that the battery temperature can reach, dynamically set considering ambient temperature, theoretical temperature rise, and battery degradation status. For example, at an ambient temperature of 25 degrees Celsius, a charging current of 5 amps, and a total internal resistance of 80 milliohms, the theoretical heat generation power is 5^2 × 0.08 = 2.0 watts. If the thermal resistance coefficient is 8 degrees Celsius per watt, the theoretical temperature rise is 2.0 × 8 = 16 degrees Celsius. If the internal resistance reference value is 60 milliohms, the internal resistance growth factor is 80 / 60 = 1.33, and the attenuation coefficient is 0.8, the temperature correction coefficient is exp(-0.8 × 0.33) = 0.767.

[0044] The system reads real-time temperature data from an ambient temperature sensor, performs a moving average filter on the raw data with a window length of the last 5 samples, and checks the filtered values ​​to ensure they are within the effective range of -10 to 50 degrees Celsius. If the values ​​exceed this range, a sensor fault alarm is triggered, and the historical average value is used instead. The ambient temperature that passes the verification is stored in a temporary variable. The system reads the current charging current and the total internal resistance of the battery, calculates the theoretical heat generation power according to Joule's law formula P = I^2 × R_total, reads the preset thermal resistance coefficient from the battery thermal model parameter library, and calculates the theoretical temperature rise value according to the formula ΔT_theory = P × R_th. The temperature rise value is checked for reasonableness; if it exceeds 20 degrees Celsius, an abnormal alarm is triggered. The system queries the preset internal resistance benchmark value from the battery parameter database, calculates the internal resistance growth factor according to the formula α = R_total / R_ref, and limits the value to a range of 0.8 to 3.0. If it exceeds 3.0, a severe battery degradation alarm is triggered. The system reads the attenuation coefficient k from the charging control parameter library, with a typical value of 0.8, and calculates the temperature correction coefficient according to the exponential attenuation function formula β = exp(-k × (α - 1)). The correction coefficient is limited to a range of 0.5 to 1.0 to ensure the protection level. The system calculates the protection temperature threshold according to the formula T_protect = T_ambient + ΔT_theory × β + ΔT_margin, where T_ambient is the current ambient temperature and ΔT_margin is a typical safety margin of 5 to 10 degrees Celsius. The calculation result is compared with the typical value of 60 degrees Celsius, which is the absolute maximum allowable temperature of the battery material. The smaller value is taken as the final protection temperature threshold. The final threshold is checked for reasonableness to ensure that it is at least 2 degrees Celsius higher than the ambient temperature. If it does not meet the requirement, the threshold is set to the ambient temperature plus 2 degrees Celsius and an alarm is triggered. The final protection temperature threshold is stored in the configuration register of the charging control module for real-time comparison by the temperature monitoring thread. At the same time, it is recorded in the battery health record with complete calculation parameters and timestamps for subsequent analysis.

[0045] Here, the current ambient temperature refers to the real-time temperature of the environment in which the target lithium battery is located, measured by a temperature sensor installed near the battery. The protection temperature threshold represents the maximum allowable operating temperature of the battery; when the battery temperature exceeds this threshold, the system must trigger temperature protection measures. Dynamic setting means that the protection temperature threshold is a variable threshold calculated in real-time based on the battery's total internal resistance and the current ambient temperature. Theoretical heat generation power represents the heat power generated by the battery's internal resistance during charging. The internal resistance growth factor represents the percentage increase in the current battery's total internal resistance relative to a preset internal resistance benchmark. The temperature correction coefficient is a correction parameter used to adjust the protection temperature threshold; this coefficient is calculated using a nonlinear function based on the internal resistance growth factor.

[0046] Specifically, the system acquires the current ambient temperature through a temperature acquisition module. Based on the battery's total internal resistance and the current charging current, it calculates the theoretical heat generation power, which is equal to the square of the charging current multiplied by the battery's total internal resistance. The system reads preset thermal resistance coefficient parameters and calculates the theoretical temperature rise, which is equal to the theoretical heat generation power multiplied by the thermal resistance coefficient. The system calculates the internal resistance growth factor, which is equal to the current total battery internal resistance divided by a preset internal resistance baseline value, and calculates the temperature correction coefficient using a nonlinear decay function. For example, when using an exponential decay function, the temperature correction coefficient is equal to e^(-k) multiplied by the internal resistance growth factor minus 1, where k is the decay coefficient. The system calculates the protection temperature threshold, which is equal to the current ambient temperature plus the theoretical temperature rise multiplied by the temperature correction coefficient plus a preset temperature margin. Through this dynamic calculation method, the protection temperature threshold can be adjusted in real time according to the ambient temperature and the battery's internal resistance status.

[0047] In some embodiments, the dynamic setting of the protection temperature threshold can be achieved in several ways: Optionally, the system reads the current ambient temperature and charging current, calculates the theoretical heat generation power by multiplying the square of the charging current by the total internal resistance of the battery, reads the thermal resistance coefficient to calculate the theoretical temperature rise, reads the preset internal resistance reference value to calculate the internal resistance growth factor, sets the attenuation coefficient k equal to 1 to calculate the temperature correction coefficient, reads the preset temperature margin to calculate the protection temperature threshold and stores it in the protection parameter variable; Optionally, the system uses a piecewise linear function to calculate the temperature correction coefficient. When the internal resistance growth factor is less than or equal to 1, the temperature correction coefficient is set to 1. When the internal resistance growth factor is greater than 1 and less than or equal to 1.5, the temperature correction coefficient is calculated as 1.5 minus the internal resistance growth factor divided by 0.5. When the internal resistance growth factor is greater than 1.5, the temperature correction coefficient is set to 0.3. The protection temperature threshold is calculated and updated based on the current ambient temperature and the theoretical temperature rise. It is understood that other nonlinear functions or lookup table interpolation methods can also be used to achieve the dynamic setting of the protection temperature threshold, which is not limited here.

[0048] In some embodiments, this step specifically includes:

[0049] Obtain the current ambient temperature of the target lithium battery; calculate the theoretical heat generation power based on the total internal resistance of the battery and the current charging current, and calculate the theoretical temperature rise based on the preset thermal resistance coefficient; calculate the ratio of the total internal resistance of the battery to the preset internal resistance benchmark value as the internal resistance growth factor, and calculate the temperature correction coefficient through a nonlinear decay function. This temperature correction coefficient decreases nonlinearly with the internal resistance growth factor; determine the protection temperature threshold based on the current ambient temperature, the theoretical temperature rise value, and the temperature correction coefficient.

[0050] The current ambient temperature refers to the real-time temperature of the space where the lithium battery is located, acquired by an independently placed ambient temperature sensor, and serves as the starting point for calculating the battery temperature rise. The theoretical heat output power refers to the Joule heat output generated by the battery's internal resistance under the current charging current conditions, calculated using the formula P = I^2 × R_total, where I is the charging current and R_total is the total internal resistance of the battery. The thermal resistance coefficient refers to the thermal impedance parameter conducted from the battery's interior to the external environment, measured in degrees Celsius per watt, with a typical range of 1 to 5 degrees Celsius per watt, characterizing the temperature rise per unit power. The theoretical temperature rise value refers to the temperature rise generated when the theoretical heat output power is conducted to the environment through the thermal resistance coefficient under steady-state conditions, calculated using the formula ΔT_theory = P × R_th. The internal resistance growth factor is the ratio of the current total internal resistance of the battery to a preset internal resistance benchmark value, calculated using the formula α = R_total / R_ref, where R_ref is the nominal total internal resistance of a healthy, fresh battery; this factor quantifies the degree of internal resistance growth caused by battery aging. The temperature correction factor is a temperature adjustment factor calculated using a nonlinear decay function based on the internal resistance growth factor. It is calculated according to the formula β = exp(-k × (α - 1)), where k is a typical decay factor ranging from 0.5 to 1.2. This factor decreases as the internal resistance growth factor increases to reduce the allowable temperature rise of a degraded battery. The protection temperature threshold is the highest safe upper limit that the battery temperature can reach. It is calculated according to the formula T_protect = T_ambient + ΔT_theory × β + ΔT_margin, dynamically set considering ambient temperature, theoretical temperature rise, and battery degradation state. For example, with an ambient temperature of 25 degrees Celsius, a charging current of 5 amps, and a total internal resistance of 80 milliohms, the theoretical heat output is 2.0 watts, the theoretical temperature rise is 16 degrees Celsius, the internal resistance base value of 60 milliohms corresponds to an internal resistance growth factor of 1.33, and the temperature correction factor is 0.767 when the decay factor is 0.8. With a safety margin of 8 degrees Celsius, the protection temperature threshold is 25 + 16 × 0.767 + 8 = 45.27 degrees Celsius.

[0051] The system reads real-time temperature data from an ambient temperature sensor, performs a moving average filter on the raw data with a window length of the most recent 5 samples to eliminate short-term fluctuations, and checks the filtered values ​​to ensure they are within the effective range of -10 to 50 degrees Celsius. If the values ​​exceed this range, a sensor fault alarm is triggered, and the historical average value is used instead. The verified ambient temperature is stored in a temporary variable for subsequent calculations. The system reads the current charging current and the total internal resistance of the battery, calculates the theoretical heat generation power in watts according to Joule's law formula P = I^2 × R_total, and reads the preset thermal resistance coefficient from the battery thermal model parameter library. This parameter is pre-calibrated according to the battery model and heat dissipation conditions. The theoretical temperature rise value in degrees Celsius is calculated according to the formula ΔT_theory = P × R_th. The temperature rise value is checked for reasonableness; if it exceeds 20 degrees Celsius, an abnormal alarm is triggered, indicating an abnormal charging parameter setting. The system queries the battery parameter database for a preset internal resistance benchmark value, which corresponds to the nominal total internal resistance of a healthy, fresh battery. It calculates the internal resistance growth factor according to the formula α = R_total / R_ref, and limits the value to a range of 0.8 to 3.0 to avoid abnormally low or excessively high values. If the value exceeds 3.0, a severe battery degradation alarm is triggered. The system reads the decay coefficient k of the nonlinear decay function from the charging control parameter library and calculates the temperature correction coefficient according to the exponential decay function formula β = exp(-k ×(α - 1)). The correction coefficient is limited to a range of 0.5 to 1.0 to ensure the minimum protection level and avoid excessive relaxation of the limits. The system calculates the initial protection temperature threshold using the formula T_protect = T_ambient + ΔT_theory × β + ΔT_margin, where T_ambient is the current ambient temperature and ΔT_margin is a typical safety margin of 5 to 10 degrees Celsius to ensure a buffer space for short-term heat accumulation. The calculation result is compared with the absolute maximum allowable temperature T_max of the battery material, which is determined based on the battery chemistry system and is typically 55 to 60 degrees Celsius for lithium-ion batteries. The smaller of the two values ​​is taken as the final protection temperature threshold to avoid excessively high thresholds due to improper calculation parameter settings. The final threshold is verified for rationality to ensure it is at least 2 degrees Celsius higher than the ambient temperature to guarantee charging feasibility. If this condition is not met, the threshold is set to the ambient temperature plus 2 degrees Celsius, and an alarm is triggered to indicate that the charging parameters need to be adjusted. The final protection temperature threshold is stored in the configuration register of the charging control module for real-time comparison by the temperature monitoring thread. At the same time, it is recorded in the battery health record along with complete calculation parameters such as timestamp, ambient temperature, theoretical temperature rise, correction factor, safety margin, and final threshold for subsequent trend analysis and audit traceability.

[0052] S104. During constant current charging, perform charging status assessment according to the preset assessment cycle, calculate the rate of change of the current total internal resistance of the battery relative to the previous assessment cycle, and weight and fuse the rate of change of internal resistance, the current temperature rise rate of the target lithium battery and the current charging voltage change rate to obtain a comprehensive score.

[0053] The preset evaluation cycle refers to the duration of the cycle in which the system performs charging status evaluation at fixed time intervals during constant current charging. This cycle is typically set to 30 to 300 seconds. Charging status evaluation represents a comprehensive assessment of the battery's current charging safety and health status. The internal resistance change rate represents the percentage change in the battery's total internal resistance relative to the total internal resistance measured in the previous evaluation cycle. The current temperature rise rate refers to the rate at which the battery temperature rises per unit time. The current charging voltage change rate represents the rate at which the battery terminal voltage changes per unit time. The comprehensive score represents the overall safety index of the charging status. Current disturbance refers to a small-amplitude current change signal superimposed on a constant charging current; this disturbance is used to excite the battery to generate a voltage response to remeasure the internal resistance parameters.

[0054] Specifically, during constant current charging, the system triggers a charging status assessment task periodically according to a preset evaluation cycle. The system monitors the stability of the current charging current. When the charging current fluctuation is less than 2% of a set value, a current disturbance signal is applied to the target lithium battery, and voltage response data is collected to calculate the current total internal resistance of the battery. The system calculates the internal resistance change rate as the difference between the current total internal resistance and the total internal resistance of the battery in the previous cycle, divided by the total internal resistance of the battery in the previous cycle, and converted to a percentage. The system calculates the current temperature rise rate by calculating the time derivative from continuously collected temperature data and the current charging voltage change rate by calculating the time derivative from voltage data. The system dynamically adjusts the weighting coefficients based on the ratio of the internal resistance change rate to the current temperature rise rate. When the internal resistance change rate exceeds a preset threshold, the weighting coefficient of the current temperature rise rate is increased. The system performs a weighted fusion calculation of the internal resistance change rate, the current temperature rise rate, and the current charging voltage change rate to calculate the current comprehensive score. The current comprehensive score is then time-weighted and accumulated to obtain a cumulative risk score, which serves as the final comprehensive score.

[0055] In some embodiments, charging status assessment can be implemented in multiple ways: Optionally, the system triggers an assessment task in a timer interrupt, and after determining that the charging current is stable, applies a positive step disturbance with an amplitude of 15% of the current charging current for 200 milliseconds. Voltage data is collected at a sampling frequency of 2000Hz, and the current total internal resistance of the battery is calculated. The rate of change of internal resistance is calculated, and the temperature and voltage data of the most recent 30 seconds are linearly fitted to obtain the temperature rise rate and voltage change rate. Weighting coefficients are dynamically set based on whether the rate of change of internal resistance exceeds 5%. After normalizing the three parameters, a weighted fusion is performed to obtain the current comprehensive score, and an exponentially weighted moving average method is used to calculate the cumulative risk score. Optionally, the system uses a fuzzy logic method, inputting each parameter into a fuzzy inference system, and inferring the fuzzy value of the risk score based on a fuzzy rule base. The fuzzy value is defuzzified to obtain the current comprehensive score, and the weighted average of the comprehensive scores of the most recent 5 assessment periods is calculated as the cumulative risk score. It is understood that other multi-parameter fusion algorithms can also be used to achieve comprehensive assessment of the charging status, and this is not limited here.

[0056] In some embodiments, this step specifically includes:

[0057] During constant current charging, the stability of the current charging current is monitored according to a preset evaluation cycle. When the current charging current meets the preset stability conditions, a current perturbation is applied to the target lithium battery and the current total internal resistance of the battery is measured. The rate of change of the current total internal resistance of the battery relative to the previous evaluation cycle is calculated. The current temperature rise rate and the current charging voltage change rate of the target lithium battery are obtained. The weighting coefficient is dynamically adjusted according to the ratio of the internal resistance change rate to the current temperature rise rate. When the internal resistance change rate exceeds a preset threshold, the weighting coefficient of the current temperature rise rate is increased. The internal resistance change rate, the current temperature rise rate, and the current charging voltage change rate are weighted and fused to obtain the current comprehensive score. The current comprehensive score is time-weighted and accumulated to obtain the cumulative risk score, which is used as the comprehensive score.

[0058] The preset evaluation cycle refers to the fixed time interval for performing charging state evaluation during constant current charging. This cycle balances the evaluation frequency with the system's computational load. Current charging current stability refers to the fluctuation range of the charging current within a certain time window, evaluated by calculating the standard deviation. The stability condition is that the standard deviation is less than a set threshold. Current disturbance refers to small-amplitude, short-term current changes applied to the battery, used to measure dynamic internal resistance. Internal resistance change rate refers to the relative change in the battery's total internal resistance measured in the current evaluation cycle compared to the previous cycle, calculated using the formula r_R = (R_current - R_previous) / R_previous, reflecting the time-varying characteristics of the battery's internal resistance. Temperature rise rate refers to the rate of change of battery temperature over time, calculated using the formula v_T = (T_current - T_previous) / Δt, reflecting the battery's heat accumulation trend. Charging voltage change rate refers to the rate of change of charging voltage over time, calculated using the formula v_V = (V_current - V_previous) / Δt, reflecting the evolution of the battery's charging state. The weighting coefficient refers to the importance coefficient assigned to each evaluation indicator in the weighted fusion, and is dynamically adjusted according to the ratio of the internal resistance change rate to the temperature rise rate. The comprehensive score is a dimensionless evaluation indicator obtained by weighted fusion of the internal resistance change rate, temperature rise rate, and voltage change rate, calculated according to the formula S = w_R × r_R + w_T × v_T + w_V × v_V; a higher value indicates a greater charging risk. The cumulative risk score is a long-term risk indicator obtained by time-weighted accumulation of historical comprehensive scores, calculated according to the formula S_cumulative = sum(λ^i × S_i), where λ is the time decay factor, reflecting the impact of historical charging states on current risk.

[0059] During constant current charging, the system starts an evaluation cycle timer to trigger charging status evaluation tasks according to a preset cycle. When the timer expires, it collects historical charging current data within the most recent time window, calculates the current standard deviation, and evaluates stability. The standard deviation is compared with a preset stability threshold. If the current is unstable, the evaluation is skipped and delayed to the next cycle. When the current meets the stability condition, the system sends a current disturbance command to the charging control module. The control module adds a small-amplitude, short-term current change to the current charging current. During the disturbance, the system collects battery terminal voltage data at high frequency. Based on the voltage response and current change, it calculates the current total battery internal resistance according to Ohm's law formula R = ΔV / ΔI. The measurement results are filtered to eliminate noise interference. The system reads the historical total battery internal resistance value stored in the previous evaluation cycle and calculates the internal resistance change rate according to the formula r_R = (R_current - R_previous) / R_previous. The change rate is checked for reasonableness and limited to an effective range to avoid abnormal measurement values ​​affecting the evaluation results. The system reads the current battery temperature and the temperature of the previous cycle from the temperature sensor, and calculates the temperature rise rate according to the formula v_T = (T_current - T_previous) / Δt. It reads the current charging voltage and the voltage of the previous cycle from the voltage sensor, and calculates the voltage change rate according to the formula v_V = (V_current - V_previous) / Δt. The system dynamically adjusts the weighting coefficients based on the ratio of the internal resistance change rate to the temperature rise rate, calculating the ratio ratio = r_R / v_T. When the internal resistance change rate exceeds a preset threshold, the weighting coefficient for the temperature rise rate is increased, while the weighting coefficients for the internal resistance change rate and the voltage change rate are correspondingly decreased to maintain a sum of 1. The weighting adjustment strategy uses a piecewise linear function to ensure a smooth transition. The system calculates the current comprehensive score according to the weighted fusion formula S = w_R × r_R + w_T × v_T + w_V × v_V, and normalizes the comprehensive score to map it to a standard range for subsequent comparison and judgment. The system reads the historical comprehensive score sequence and extracts the score values ​​of the most recent evaluation periods from the database. It calculates the cumulative risk score according to the time-weighted cumulative formula S_cumulative = sum(λ^i × S_i), where λ is the time decay factor indicating that the weight index of the more distant history decreases, and i is the time index from the current period to the earliest period. The cumulative risk score is used as the final comprehensive score output. This score comprehensively reflects the instantaneous risk of the current charging state and the historical cumulative risk. It is stored in the battery health record with detailed parameters such as timestamp, internal resistance change rate, temperature rise rate, voltage change rate, and weight coefficient for subsequent analysis.

[0060] S105. Adjust the current charging current based on the comprehensive score, and constrain the adjustment range of the current charging current based on the current total internal resistance of the battery. Update the protection temperature threshold based on the adjusted charging current and the current total internal resistance of the battery.

[0061] The charging current adjustment amount represents the amount of current change required to increase or decrease the current charging current, calculated based on a comprehensive score. The maximum allowable adjustment range refers to the maximum permissible change in charging current during a single adjustment, determined by the internal resistance growth factor. The charging power change amount represents the change in battery charging power after adjusting the charging current. The current heat dissipation capacity represents the battery's ability to dissipate heat to the environment at the current temperature. The actual adjustment amount represents the actual charging current adjustment applied after multiple constraints. The theoretical heat generation power after adjustment refers to the theoretical heat generation power generated by the battery due to its internal resistance when charging with the adjusted charging current.

[0062] Specifically, the system calculates the charging current adjustment amount using a proportional control strategy based on the comprehensive score. When the comprehensive score is higher than the target score, the adjustment amount is negative, indicating that the charging current needs to be reduced. The system determines the maximum allowable adjustment range using an inverse proportional function based on the internal resistance growth factor. When the internal resistance growth factor is large, the maximum allowable adjustment range decreases accordingly. The system calculates the changes in the adjusted charging current and charging power, and estimates the power upper limit corresponding to the current heat dissipation capacity based on the current temperature rise rate. The system constrains the charging current adjustment amount, first limiting the adjustment amount to the maximum allowable adjustment range, and then determining whether the adjusted power exceeds the power upper limit. If it does, the adjustment amount is further reduced, resulting in the actual adjustment amount after constraint processing. The system adjusts the current charging current based on the actual adjustment amount, calculates the theoretical heat generation power after adjustment, which is equal to the square of the adjusted charging current multiplied by the current total internal resistance of the battery, and updates the protection temperature threshold based on the theoretical heat generation power after adjustment and the current ambient temperature.

[0063] In some embodiments, charging current regulation can be achieved in multiple ways: Optionally, the system sets a target score and a proportional coefficient to calculate the charging current regulation amount, calculates the maximum allowable regulation range based on the internal resistance growth factor, calculates the regulated charging current after limiting the regulation amount, calculates the upper limit of power based on the current temperature rise rate and thermal resistance coefficient, compares the regulated charging power with the upper limit of power to determine the actual regulation amount, sends a current update command to the charging control module, calculates the theoretical heat generation power after regulation, and updates the protection temperature threshold; Optionally, the system adopts a model predictive control method to establish a dynamic prediction model of battery temperature, sets an optimization target based on the comprehensive score, uses a sequential quadratic programming algorithm to solve for the optimal regulation amount that satisfies the temperature constraint and internal resistance constraint, updates the charging current based on the actual regulation amount, and calculates the protection temperature threshold. It is understood that other control algorithms can also be used to achieve constrained regulation of the charging current and dynamic updating of the protection temperature threshold, which is not limited here.

[0064] In some embodiments, this step specifically includes:

[0065] The charging current adjustment amount is determined based on the comprehensive score. The maximum allowable adjustment range is determined based on the internal resistance growth factor of the current total battery internal resistance relative to the preset internal resistance benchmark value. The change in charging power is calculated based on the adjusted charging current. The current heat dissipation capacity is estimated based on the current temperature rise rate. The charging current adjustment amount is constrained within the maximum allowable adjustment range and the power upper limit corresponding to the current heat dissipation capacity to obtain the actual adjustment amount. The current charging current is adjusted based on the actual adjustment amount. The theoretical heat generation power after adjustment is calculated based on the adjusted charging current and the current total battery internal resistance. The protection temperature threshold is updated based on the theoretical heat generation power and the current ambient temperature.

[0066] The charging current adjustment refers to the increase or decrease in charging current calculated based on a comprehensive score. The comprehensive score is mapped to the current adjustment using a piecewise linear function or lookup table; a higher comprehensive score results in a more negative adjustment, indicating a reduction in charging current. The internal resistance growth factor is the ratio of the current total internal resistance of the battery to a preset internal resistance baseline value, calculated using the formula α = R_total / R_ref. This factor quantifies the degree of battery aging and is used to constrain the current adjustment range. The maximum allowable adjustment range refers to the upper limit of a single current adjustment determined based on the internal resistance growth factor, preventing excessive current changes from causing battery stress. It is calculated using the formula ΔI_max = I_base × (2 - α); a larger internal resistance growth factor results in a smaller maximum allowable adjustment range. The charging power change refers to the change in charging power caused by adjusting the charging current, calculated using the formula ΔP = (I_new^2 - I_old^2) × R_total, reflecting the impact of the adjustment on battery heating. The current heat dissipation capacity refers to the upper limit of the battery's heat dissipation power under current environmental conditions. It is estimated based on the temperature rise rate and calculated using the formula P_dissipation = (T_max - T_current) / R_th, representing the battery's remaining thermal capacity. The power upper limit refers to the maximum value of the charging power increment determined based on the heat dissipation capacity, ensuring that adjusted charging will not cause temperature exceedances. The actual adjustment amount refers to the final charging current adjustment value after multiple constraint processing, simultaneously satisfying the constraints of the maximum allowable adjustment range and the power upper limit corresponding to the heat dissipation capacity. The theoretical heat generation power after adjustment refers to the Joule heat power generated by the new charging current after applying the actual adjustment amount, calculated using the formula P_new = I_new^2 × R_total, used to update the protection temperature threshold. The updated protection temperature threshold refers to the temperature protection upper limit recalculated based on the adjusted charging current and theoretical heat generation power, calculated using the formula T_protect_new = T_ambient + P_new × R_th × β + ΔT_margin to ensure the thermal safety of adjusted charging.

[0067] The system reads the current comprehensive score value and maps it to the charging current adjustment amount according to a preset piecewise linear function or lookup table. The mapping relationship is set so that the higher the comprehensive score, the greater the current reduction to reduce charging risk. The system reads the current total internal resistance of the battery and the preset internal resistance benchmark value, calculates the internal resistance growth factor according to the formula α = R_total / R_ref, and calculates the maximum allowable adjustment range according to the formula ΔI_max = I_base × (2 - α) based on the internal resistance growth factor. The maximum allowable adjustment range is limited to ensure that it is not less than the minimum threshold to guarantee minimum adjustment flexibility. The system reads the current charging current and calculates the adjusted charging current according to the formula I_new = I_current + ΔI. The charging power change is calculated according to the formula ΔP =(I_new^2 - I_current^2) × R_total. The system reads the current battery temperature and the protection temperature threshold, reads the thermal resistance coefficient from the battery thermal model parameter library, and estimates the current heat dissipation capacity according to the formula P_dissipation = (T_protect - T_current) / R_th. The heat dissipation capacity is used as the power upper limit to constrain the charging power change. The system compares the absolute value of the adjusted charging current with the maximum allowable adjustment range. If the absolute value of the adjusted current exceeds the maximum allowable adjustment range, the adjustment is limited to the maximum allowable adjustment range. It then compares the change in charging power caused by the adjustment with the upper power limit corresponding to the heat dissipation capacity. If the power change exceeds the upper power limit, it calculates the maximum allowable current adjustment in reverse, taking the smaller value between the original adjustment and the power constraint adjustment as the actual adjustment. The actual adjustment is then validated to ensure that the adjusted charging current is within the allowable range. The system calculates the adjusted charging current according to the formula I_adjusted = I_current + ΔI_actual, and sends a current setting command to the charging control module to update the current setting value of the constant current control loop to the adjusted charging current. The control module uses a ramp-down method during the current adjustment process to avoid sudden current changes that could cause battery stress.The system calculates the theoretical heat generation power after adjustment according to the formula P_new = I_adjusted^2 × R_total, reads the current ambient temperature, calculates the theoretical temperature rise after adjustment according to the formula ΔT_theory_new = P_new × R_th, reads the temperature correction coefficient β (which is calculated based on the internal resistance growth factor), reads the safety margin ΔT_margin, and calculates the updated protection temperature threshold according to the formula T_protect_new = T_ambient + ΔT_theory_new × β + ΔT_margin. The updated protection temperature threshold is compared with the absolute maximum allowable temperature of the battery material, and the smaller value is taken as the final protection temperature threshold. The final protection temperature threshold is stored in the charging control module configuration register to update the comparison benchmark of the temperature monitoring thread. At the same time, it is recorded in the battery health record with a timestamp, charging current before and after adjustment, actual adjustment amount, constraints, protection temperature threshold before and after update, and other detailed parameters for subsequent analysis.

[0068] The following provides a more detailed description of the process of the method provided in this implementation. Please refer to [link / reference]. Figure 2 This is another flowchart illustrating the lithium battery safe charging control method in this application embodiment.

[0069] S201. By applying a current perturbation to the target lithium battery, the current ohmic internal resistance and the current polarization internal resistance are calculated respectively. The polarization growth rate of the current polarization internal resistance is calculated over multiple consecutive evaluation periods, and the ohmic growth rate of the current ohmic internal resistance is calculated.

[0070] Current perturbation refers to a square wave or step current signal with an amplitude of 5% to 20% of the reference current and a duration of 50 to 500 milliseconds superimposed on a constant charging current, used to excite the battery to generate a measurable voltage response. Current ohmic internal resistance refers to the battery ohmic impedance value obtained by analyzing the voltage transient response at the current evaluation moment. Current polarization internal resistance refers to the battery polarization impedance value obtained by analyzing the voltage delay response at the current evaluation moment. Polarization growth rate refers to the change in polarization internal resistance per unit time, calculated as the linear regression slope of the polarization internal resistance over the most recent N evaluation periods, in milliohms per minute. Ohmic growth rate refers to the change in ohmic internal resistance per unit time, calculated as the linear regression slope of the ohmic internal resistance over the most recent N evaluation periods, in milliohms per minute. For example, if the polarization internal resistance of the battery measured in the 1st, 2nd, 3rd, 4th and 5th evaluation cycles are 45, 48, 52, 57 and 63 milliohms respectively, with a time interval of 1 minute, then the polarization growth rate obtained by least squares fitting is approximately 4.5 milliohms / minute.

[0071] The system applies a current perturbation signal to the target lithium battery within each preset evaluation cycle, and synchronously acquires battery terminal voltage response data at a sampling frequency of no less than 1000Hz. The system performs time-domain decomposition on the acquired voltage response data, extracting the voltage surge within 10 milliseconds after current connection as the transient response caused by ohmic resistance. The ratio of this voltage surge to the current perturbation amplitude is calculated to obtain the current ohmic resistance. The system also extracts the voltage delay change curve within a time period of 10 to 500 milliseconds, fits this curve to a first-order RC equivalent circuit model, and calculates the current polarization resistance using a parameter identification algorithm. The system stores the current ohmic resistance and current polarization resistance values ​​in a sliding window buffer queue, with a queue length set to 5 to 10 evaluation cycles. When the buffer queue reaches its set length, the system performs least-squares linear regression fitting on the polarization resistance data sequence in the queue; the slope of the regression line is the polarization growth rate. The same linear regression calculation is performed on the ohmic resistance data sequence in the queue to obtain the ohmic growth rate. The system passes the calculated polarization growth rate and ohmic growth rate to the next step for discreteness analysis. In the specific implementation, the system is configured with a current disturbance amplitude of 10% of the current charging current, a duration of 200 milliseconds, a sampling frequency of 2000 Hz, a sliding window length of 8 evaluation cycles, and an evaluation cycle interval of 60 seconds. The RC model parameter identification process is optimized using a gradient descent algorithm.

[0072] S202. Calculate the growth rate dispersion between the polarization growth rate and the ohmic growth rate.

[0073] Growth rate dispersion is a statistical indicator used to quantify the difference between the polarization growth rate and the ohmic growth rate, reflecting the inconsistency in the changing trends of these two internal resistance parameters. The calculation method uses the standardized difference method. First, the absolute difference between the polarization growth rate and the ohmic growth rate is calculated, then normalized by dividing by the average of their sums. The formula is: Growth rate dispersion equals |polarization growth rate minus ohmic growth rate| divided by (polarization growth rate plus ohmic growth rate divided by 2), and the result is a dimensionless value. For example, when the polarization growth rate is 4.5 milliohms / min and the ohmic growth rate is 1.2 milliohms / min, the calculated growth rate dispersion equals |4.5 minus 1.2| divided by (4.5 plus 1.2 divided by 2), which equals 3.3 divided by 2.85, approximately equal to 1.16. A large growth rate dispersion value indicates that the polarization effect grows significantly faster than the ohmic internal resistance, suggesting that the electrochemical reaction inside the battery is suppressed or the electrolyte mass transfer process is deteriorated.

[0074] The system reads the polarization growth rate and ohmic growth rate values ​​calculated in step S201 and calculates the absolute difference between them as the rate difference. The system calculates the arithmetic mean of the polarization growth rate and the ohmic growth rate as a normalization benchmark. The system divides the rate difference by the normalization benchmark to obtain a dimensionless growth rate dispersion index. To improve calculation stability, the system performs a moving average filtering process on the growth rate dispersion values ​​calculated over three consecutive evaluation periods to obtain a smoothed growth rate dispersion. The system compares the smoothed growth rate dispersion with a preset dispersion threshold, which is set according to the battery type and health status, typically ranging from 0.8 to 1.5. When the growth rate dispersion exceeds the preset dispersion threshold, it indicates that the polarization growth rate is significantly higher than the ohmic growth rate, and the internal polarization effect of the battery accumulates too quickly, triggering a charging mode switching signal. In the specific implementation, the system reads the polarization growth rate of 4.5 milliohms / min and the ohm growth rate of 1.2 milliohms / min, calculates the rate difference of 3.3 milliohms / min, calculates the normalized baseline value of 2.85 milliohms / min, and obtains the growth rate dispersion of 1.16. The arithmetic mean of the growth rate dispersion values ​​of the most recent three periods of 1.08, 1.12 and 1.16 is used to obtain the smoothed value of 1.12, which is compared with the preset dispersion threshold of 1.0 and then triggers the mode switching.

[0075] S203. When the growth rate dispersion exceeds the preset dispersion threshold, the constant current charging will be switched to the constant voltage charging mode with the current charging voltage as the upper limit.

[0076] Constant current charging refers to a charging mode in which the charging current remains constant during the charging process, and the battery terminal voltage increases with the state of charge. Constant voltage charging refers to a charging mode in which the battery terminal voltage remains constant during the charging process, and the charging current naturally decreases with the state of charge. The current charging voltage refers to the measured value of the battery terminal voltage at the instant of switching from constant current charging to constant voltage charging mode. This voltage value serves as the upper limit setting for constant voltage charging. The mode switching process involves switching the charging control strategy from constant current control to constant voltage control, and the control objective changes from maintaining a constant current to maintaining a constant voltage. For example, if the battery is charged at a current of 5 amps during the constant current charging phase, and the current rate of increase dispersion exceeds a threshold, the current charging voltage is measured to be 3.85 volts. The system immediately switches the charging mode to constant voltage charging with an upper limit of 3.85 volts. At this time, the charging current gradually decreases from 5 amps, and the battery terminal voltage remains at 3.85 volts.

[0077] After determining in step S202 that the growth rate dispersion exceeds a preset dispersion threshold, the system immediately reads the current battery terminal voltage value as the upper limit of the constant voltage charging voltage. The system sends a mode switching command to the charging control module, the command parameters of which include the target constant voltage value and the maximum allowable charging current limit. Upon receiving the command, the charging control module executes a control mode switch, closing the constant current control loop and starting the constant voltage control loop, configuring the voltage feedback controller's setpoint to the current charging voltage. In constant voltage control mode, the charging control module continuously monitors the battery terminal voltage and dynamically adjusts the charging current through a PI control algorithm or a PID control algorithm to stabilize the battery terminal voltage at the set upper voltage limit. Due to the accumulation of battery polarization effect, the charging current shows a rapid decreasing trend in the early stage of constant voltage charging, and the rate of decrease slows down as the polarization effect gradually eases. In constant voltage charging mode, the system continues to execute steps S201 to S202 according to the preset evaluation cycle, continuously monitoring the current polarization internal resistance change. In practice, the system detects that the growth rate dispersion has increased from 1.12 to 1.18, exceeding the threshold of 1.0. It immediately samples and obtains the current charging voltage of 3.87 volts, and sends a control command to the charging module with the following settings: mode: constant voltage, voltage limit: 3.87V, current limit: 6A. The charging module switches to a PI controller with Kp=0.5 and Ki=0.1 to achieve stable voltage control. The charging current decreases from 5.2 amps to 4.1 amps within 30 seconds.

[0078] S204. In constant voltage charging mode, continue to monitor the current polarization internal resistance according to the preset evaluation cycle. When the current polarization internal resistance falls below the preset polarization internal resistance threshold, resume constant current charging.

[0079] Polarization resistance monitoring in constant voltage charging mode refers to measuring the current value of polarization resistance by periodically applying small-amplitude current perturbations and analyzing the voltage response while the battery terminal voltage remains constant during charging. Polarization resistance decline refers to the gradual decrease in polarization resistance value from a high level, indicating that the internal polarization effect of the battery has been alleviated and the electrochemical reaction impedance has decreased. The preset polarization resistance threshold refers to the safe upper limit value of polarization resistance set in step S102. When the polarization resistance is lower than this threshold, it indicates that the battery state has returned to a healthy range suitable for constant current charging. Resuming constant current charging refers to switching back from constant voltage charging mode to constant current charging mode, recharging the battery with a constant current. For example, in constant voltage charging mode, the polarization resistance of the battery is measured to be 63 milliohms in the first evaluation cycle, 58 milliohms in the second cycle, 52 milliohms in the third cycle, 47 milliohms in the fourth cycle, and 43 milliohms in the fifth cycle. When the preset polarization resistance threshold is 45 milliohms, it is determined in the fifth cycle that the polarization resistance of 43 milliohms has fallen below the threshold, triggering the resumption of constant current charging.

[0080] During constant-voltage charging mode, the system continues to trigger charging status assessment tasks according to a preset assessment cycle. Within each assessment cycle, a small-amplitude current disturbance signal is superimposed on the constant-voltage control. This disturbance amplitude is set to 8% to 15% of the current charging current to avoid significant interference with constant-voltage control. The system collects battery terminal voltage fluctuation data during the current disturbance at a high sampling frequency, performs RC model fitting on the collected voltage response curve, and calculates the current polarization resistance value. The system compares the current polarization resistance with a preset polarization resistance threshold. When the current polarization resistance value is lower than the preset threshold, the system determines that the battery polarization effect has been sufficiently mitigated and conditions for resuming constant-current charging are met. The system reads the historical charging current value before switching to constant-voltage mode and multiplies this value by a reduction factor of 0.85 to 0.95 to obtain the initial current setting value for resuming constant-current charging. The system sends a mode recovery command to the charging control module, closing the constant-voltage control loop, starting the constant-current control loop, and configuring the current feedback controller's setpoint to the reduced constant-current charging current. After the charging control module executes the control mode switch, the battery terminal voltage continues to rise from the constant voltage set value as the charging state progresses, while the charging current remains at the set constant current value. Specifically, in constant voltage charging mode, the system applies a current disturbance with an amplitude of 12% of the current charging current for 150 milliseconds every 60 seconds, with a sampling frequency of 2000Hz. In the 5th evaluation cycle, the current polarization internal resistance of 43 milliohms is calculated to be lower than the threshold of 45 milliohms. The charging current before the constant voltage switch is read as 5.2 amps, and the recovery current is calculated as 5.2 multiplied by 0.9, equaling 4.68 amps. The system then sends the command {Mode: Constant Current, Current Setting: 4.68A}, and the charging module switches to the PI controller to resume constant current charging.

[0081] S205. When the comprehensive score is within the preset warning range for multiple consecutive evaluation cycles, the constant current charging is suspended and the system enters the resting stage.

[0082] The preset warning range refers to the numerical range within which the comprehensive score is at a critical risk level. The upper limit of this range is below the danger threshold that triggers immediate protection measures, and the lower limit is above the safety threshold for normal charging. It is typically set as a normalized score range of [0.65, 0.80]. Multiple consecutive evaluation cycles refer to the required number of cycles in which the comprehensive score remains within the preset warning range. This number is set to 3 to 5 cycles to avoid misjudgments caused by instantaneous fluctuations. The resting phase refers to the period during which charging current is suspended from the battery, leaving it in an open-circuit state. This phase is used to eliminate polarization accumulation during charging and observe the battery's natural state evolution. For example, if the comprehensive scores of the battery in evaluation cycles 1, 2, 3, 4, and 5 are 0.62, 0.71, 0.73, 0.74, and 0.72, respectively, and the preset warning range is [0.65, 0.80] with 4 consecutive judgment cycles, the resting phase is triggered when the score from cycles 2 to 5 is detected as being within the warning range for 4 consecutive cycles in the 5th cycle.

[0083] After each preset evaluation cycle, the system reads the comprehensive score calculated in step S104 and compares it with the upper and lower limits of a preset warning interval. The system maintains a sliding window buffer queue of length N to store the comprehensive scores of the most recent N evaluation cycles. The value of N is equal to the consecutive evaluation cycle requirement plus 1 for continuity judgment. When a new comprehensive score is added to the queue, the system checks whether the scores of the most recent N-1 evaluation cycles in the queue all fall within the preset warning interval. If the continuity condition is met, the system triggers a static protection mechanism, sending a pause charging command to the charging control module. The charging module immediately stops outputting charging current, and the battery enters an open-circuit static state. The system records the moment of entering the static stage as the static start time and starts the static timer. During the static stage, the system continuously monitors the battery terminal voltage changes at a frequency higher than the normal evaluation cycle, with the monitoring frequency set to collect voltage data every 5 to 10 seconds. The system stores the collected voltage time series data in the buffer queue for voltage component decomposition analysis in subsequent steps. In specific implementation, the system sets the preset warning range as [0.68, 0.78], the number of consecutive judgment cycles is 4, and the maintenance length of the scoring queue is 5. When the scores of the 2nd to 5th cycles are 0.71, 0.73, 0.74, and 0.72 respectively, all of which are within the warning range, the system triggers a standby state and sends the {Operation: Stop Charging} command. The charging module cuts off the output within 10 milliseconds. The system monitors the standby process by collecting voltage data once every 8 seconds.

[0084] S206. During the resting period, the terminal voltage change of the target lithium battery is collected, and the transient voltage drop component and the gradually changing voltage fall component in the terminal voltage change are obtained. The transient voltage drop component corresponds to the voltage released by the ohmic internal resistance, and the gradually changing voltage fall component corresponds to the voltage released by the polarization effect relaxation.

[0085] Terminal voltage change refers to the numerical sequence of battery terminal voltage evolution over time during the resting phase. This sequence reflects the transition process of the battery from the charging state to the open-circuit equilibrium state. The transient voltage drop component refers to the instantaneous decrease in battery terminal voltage caused by ohmic internal resistance at the moment the charging current stops. This voltage drop occurs within 10 milliseconds after the current stops, and its amplitude equals the charging current before it stops multiplied by the ohmic internal resistance. The gradually decreasing voltage drop component refers to the slow decrease in battery terminal voltage due to polarization relaxation after the charging current stops. This voltage drop process lasts from tens of seconds to several minutes, following an exponential decay law. The voltage released by ohmic internal resistance refers to the voltage value corresponding to the transient voltage drop component, calculated by subtracting the terminal voltage 10 milliseconds after charging stops from the terminal voltage at the moment charging stops. The voltage released by polarization relaxation refers to the voltage value corresponding to the gradually decreasing voltage drop component, calculated by subtracting the open-circuit voltage after resting and stabilization from the terminal voltage 10 milliseconds after charging stops. For example, if the charging stop voltage is 4.05 volts and the charging current is 4 amps, and the voltage drops to 3.99 volts 10 milliseconds after stopping, and the voltage stabilizes at 3.92 volts after 300 seconds, then the transient voltage drop component is 4.05 minus 3.99 equals 0.06 volts, corresponding to the release of ohmic internal resistance, and the gradual voltage drop component is 3.99 minus 3.92 equals 0.07 volts, corresponding to polarization relaxation.

[0086] At the start of the resting phase, the system acquires battery terminal voltage data at a high sampling frequency of no less than 1000Hz, continuously acquiring data for at least 1 second to capture the complete transient voltage drop process. The system extracts the last stable voltage sample value before charging stops as the reference voltage and the voltage sample value 10 milliseconds after charging stops as the transient voltage drop endpoint voltage, calculating the difference between the two to obtain the transient voltage drop component. During the resting phase, the system continuously acquires battery terminal voltage data every 5 to 10 seconds to construct a voltage time series curve. The system performs exponential function fitting on the voltage time series from 10 milliseconds after the start of the resting phase to the end of the resting phase. The fitting function is V(t) equal to Voc plus ΔVp multiplied by the negative t of e divided by τ, where Voc is the open-circuit voltage, ΔVp is the polarization voltage amplitude, and τ is the time constant. The system identifies the fitting function parameters using a nonlinear least squares method; the obtained ΔVp parameter is the slowly varying voltage drop component. The system calculates the estimated ohmic internal resistance by dividing the transient voltage drop component by the current value before charging stops, and calculates the estimated polarization internal resistance by dividing the gradually changing voltage fall component by the current value before charging stops. The system stores the two voltage components and their corresponding internal resistance estimates in historical records for subsequent health status assessments and charging strategy optimization. Specifically, the system samples the voltage before charging stops (4.05V) and the voltage 10ms after stopping (3.99V) at 2000Hz, calculates the transient drop of 0.06V, and obtains the voltage sequence during the rest period at a sampling frequency of 8 seconds. Fitting the voltage data after 10ms yields Voc=3.92V, ΔVp=0.07V, and τ=45s. The calculated ohmic internal resistance is 0.06 divided by 4, equaling 15 milliohms, and the polarization internal resistance is 0.07 divided by 4, equaling 17.5 milliohms, which are then stored in the database.

[0087] S207. Calculate the polarization relaxation ratio of the slowly varying voltage drop component relative to the transient voltage drop component.

[0088] The polarization relaxation ratio is the ratio of the gradually decreasing voltage drop component to the transient voltage drop component during the resting phase. This ratio quantifies the severity of the battery's polarization effect relative to the ohmic effect. It is calculated as follows: the polarization relaxation ratio equals the gradually decreasing voltage drop component divided by the transient voltage drop component, resulting in a dimensionless value. This ratio reflects the relative relationship between the battery's internal polarization impedance and ohmic impedance. A higher polarization relaxation ratio indicates a more severe accumulation of polarization effects, requiring a more cautious charging strategy. For example, when the gradually decreasing voltage drop component is 0.07 volts and the transient voltage drop component is 0.06 volts, the polarization relaxation ratio is approximately 1.17 (0.07 divided by 0.06). If the gradually decreasing component is 0.12 volts and the transient component is 0.05 volts, the polarization relaxation ratio is 2.40, significantly higher than the former, indicating that the polarization effect dominates. A polarization relaxation ratio below 1.0 indicates that the ohmic effect dominates, 1.0 to 2.0 indicates that polarization and the ohmic effect are comparable, and a ratio above 2.0 indicates that the polarization effect is significantly dominant and the charging intensity needs to be reduced.

[0089] The system reads the values ​​of the gradually decreasing voltage drop component and the transient voltage drop component obtained from step S206. The system performs a division operation to calculate the polarization relaxation ratio, calculated as follows: Polarization relaxation ratio equals the gradually decreasing voltage drop component divided by the transient voltage drop component. To avoid division by zero errors, the system checks whether the transient voltage drop component is greater than a minimum threshold of 0.01 volts before calculation. If it is less than this threshold, the polarization relaxation ratio is set to a preset maximum value of 10.0, indicating severe polarization dominance. The system performs a rationality check on the calculated polarization relaxation ratio. If the value exceeds 10.0, it is limited to 10.0; if the value is less than 0.1, it is limited to 0.1. The system stores the calculated polarization relaxation ratio value in the battery health record as an important parameter for charging strategy adjustment and health status diagnosis. The system then passes the polarization relaxation ratio to step S208 to determine the reduction factor for the recovery charging current. In the specific implementation, the system reads the slowly changing voltage drop component of 0.07 volts and the transient voltage drop component of 0.06 volts, calculates the polarization relaxation ratio as 0.07 divided by 0.06 equals 1.167, verifies that this value is within a reasonable range [0.1, 10.0], stores it in the database to record the timestamp 2026-05-21 14:32:18 and the polarization relaxation ratio 1.167, and then passes it to the next step.

[0090] S208. Determine the recovery charging current based on the polarization relaxation ratio, and re-perform constant current charging on the target lithium battery using the recovery charging current. Then, reset the protection temperature threshold based on the recovery charging current and the current total internal resistance of the battery.

[0091] The recovery charging current refers to the charging current value set when constant current charging is restarted after the resting phase. This current value is dynamically adjusted according to the polarization relaxation ratio to match the current battery state. The current reduction factor is a current adjustment factor calculated based on the polarization relaxation ratio, used to multiply the charging current before resting by this factor to obtain the recovery charging current. The current total battery internal resistance refers to the sum of the ohmic internal resistance and the polarization internal resistance; this parameter reflects the overall impedance characteristics of the battery to the charging current. The protection temperature threshold refers to the maximum temperature the battery is allowed to reach. When the battery temperature exceeds this threshold, charging is immediately stopped to avoid the risk of thermal runaway. The protection temperature threshold is dynamically calculated based on the product of the battery's total internal resistance and the charging current, as well as the battery's heat dissipation capacity. For example, if the charging current before resting is 4 amps, the polarization relaxation ratio is 1.17 corresponding to a current reduction factor of 0.88, and the recovery charging current is 4 multiplied by 0.88, which equals 3.52 amps. If the total internal resistance of the battery is 80 milliohms, the charging power consumption is 3.6 squared multiplied by 0.08, which equals 1.037 watts. Combining the thermal resistance coefficient of 10 degrees Celsius per watt and the initial temperature of 28 degrees Celsius, the theoretical temperature rise is 1.037 multiplied by 10, which equals 10.37 degrees Celsius. With a temperature correction factor of 0.767 and a safety margin of 8 degrees Celsius, the protection temperature threshold is set to 28 plus 10.37 multiplied by 0.767 plus 8, which equals 43.95 degrees Celsius.

[0092] The system reads the polarization relaxation ratio value and maps it to a current reduction factor according to a preset piecewise linear function or lookup table. The mapping relationship is set as follows: the reduction factor is 0.95 when the polarization relaxation ratio is less than 0.8, 0.90 when it is between 0.8 and 1.2, 0.85 when it is between 1.2 and 1.8, 0.78 when it is between 1.8 and 2.5, and 0.70 when it is greater than 2.5. The system reads the historical charging current value before entering the resting stage and multiplies this historical value by the current reduction factor to obtain the recovery charging current. The system reads the estimated ohmic internal resistance and polarization internal resistance values ​​calculated in step S206 and adds them together to obtain the current total battery internal resistance. The system calculates the charging power consumption as the square of the recovery charging current multiplied by the current total battery internal resistance, in watts. The system reads the heat dissipation coefficient from the battery thermal model parameters. This coefficient represents the heat dissipation power per unit temperature rise, in watts per degree Celsius. The system reads the current ambient temperature and the current battery temperature, calculates the steady-state temperature rise as the charging power consumption divided by the heat dissipation coefficient, and calculates the protection temperature threshold as the current battery temperature plus the steady-state temperature rise plus a safety margin of 5 degrees Celsius. The system compares the protection temperature threshold with the maximum allowable temperature of the battery material (60 degrees Celsius) and takes the smaller value as the final protection temperature threshold. The system sends a resumption charging command to the charging control module, with parameters including the resumption charging current and the protection temperature threshold. The charging control module starts the constant current control loop, configures the current setpoint to the resumption charging current, and simultaneously starts the temperature monitoring thread.

[0093] S209. When the battery temperature does not reach the protection temperature threshold, continue constant current charging and enter the next evaluation cycle until the battery temperature reaches the protection temperature threshold and then stop charging.

[0094] Constant current charging continues until the temperature protection condition or other stopping conditions are triggered. Temperature monitoring involves the system acquiring battery temperature sensor data at a high frequency during charging and comparing it in real-time with the protection temperature threshold. Evaluation cycle repeats after charging resumes, continuing to execute the charging status evaluation process from S101 to S104 according to the preset evaluation cycle to continuously monitor battery health and charging safety. Charging stop when temperature reaches the protection threshold occurs when the battery temperature reaches or exceeds the protection temperature threshold set in step S208; in this case, the charging control module immediately cuts off the charging current, and the battery enters a stopped charging or cooling / resting state.

[0095] After the charging control module initiates constant current charging, the system simultaneously starts a temperature monitoring thread and an evaluation cycle timer. The temperature monitoring thread reads battery temperature sensor data every 3 to 8 seconds, comparing the collected temperature values ​​with the protection temperature threshold set in step S208. If the temperature value is lower than the protection temperature threshold minus a safety margin of 1 degree Celsius, the temperature monitoring thread does not perform any operation and continues monitoring in the next cycle. If the temperature value enters the warning range between the protection temperature threshold minus 1 degree Celsius and the protection temperature threshold, the temperature monitoring thread writes a warning message to the log system but does not interrupt charging. If the temperature value reaches or exceeds the protection temperature threshold, the temperature monitoring thread immediately sends an emergency stop command to the charging control module, and the charging control module cuts off the charging current output within 10 milliseconds. The evaluation cycle timer triggers the charging status evaluation task according to the preset evaluation cycle. The system executes step S101 to collect battery parameters, step S102 to calculate evaluation indicators, step S103 to extract feature parameters, and step S104 to calculate a comprehensive score. Based on the comprehensive score, it determines whether to execute the mode switching or static protection process in steps S201 to S206. At the end of each evaluation cycle, the system updates the battery health profile, recording key data such as current charging current, battery temperature, overall score, and internal resistance parameters. When the temperature monitoring thread triggers a charging stop, the system records all battery parameters at the moment of stop, generates a charging end report, indicates that the reason for the stop is that the temperature has reached the protection threshold, and sets the battery status to a state awaiting cooling.

[0096] The lithium battery safe charging control system in the embodiments of this invention is described below from the perspective of hardware processing. Please refer to [link / reference needed]. Figure 3 This is a schematic diagram of the physical device structure of a lithium battery safe charging control system in the embodiments of this application.

[0097] It should be noted that, Figure 3 The structure of the lithium battery safe charging control system shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of the present invention.

[0098] like Figure 3 As shown, the lithium battery safe charging control system includes a CPU 301, which can perform various appropriate actions and processes according to a program stored in ROM 302 or a program loaded into RAM 303 from storage section 308, such as executing the methods described in the above embodiments. RAM 303 also stores various programs and data required for system operation. The CPU 301, ROM 302, and RAM 303 are interconnected via bus 304. I / O interface 305 is also connected to bus 304.

[0099] The following components are connected to I / O interface 305: input section 306 including audio input devices, push-button switches, etc.; output section 307 including liquid crystal display (LCD) and audio output devices, indicator lights, etc.; storage section 308 including hard disks, etc.; and communication section 309 including network interface cards such as LAN (Local Area Network) cards, modems, etc. Communication section 309 performs communication processing via a network such as the Internet. Drive 310 is also connected to I / O interface 305 as needed. Removable media 311, such as disks, optical disks, magneto-optical disks, semiconductor memories, etc., are installed on drive 310 as needed so that computer programs read from them can be installed into storage section 308 as needed.

[0100] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing computer programs for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 309, and / or installed from removable medium 311. When the computer program is executed by CPU 301, it performs the various functions defined in the present invention.

[0101] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. Each block in a flowchart or block diagram may represent a module, program segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those shown in the drawings.

[0102] Specifically, the lithium battery safe charging control system of this embodiment includes a processor and a memory. The memory stores a computer program. When the computer program is executed by the processor, it implements the lithium battery safe charging control method provided in the above embodiment.

[0103] In another aspect, the present invention also provides a computer-readable storage medium, which may be included in the lithium battery safe charging control system described in the above embodiments; or it may exist independently and not assembled into the lithium battery safe charging control system. The storage medium carries one or more computer programs, which, when executed by a processor of the lithium battery safe charging control system, cause the lithium battery safe charging control system to implement the lithium battery safe charging control method provided in the above embodiments.

[0104] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application 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 scope of the technical solutions of the embodiments of this application.

[0105] As used in the above embodiments, depending on the context, the term "when..." can be interpreted as meaning "if...", "after...", "in response to determining...", or "in response to detecting...". Similarly, depending on the context, the phrase "when determining..." or "if (the stated condition or event) is interpreted as meaning "if determining...", "in response to determining...", "when (the stated condition or event) is detected", or "in response to detecting (the stated condition or event)".

Claims

1. A method for controlling the safe charging of a lithium battery, characterized in that, The method, applied to a lithium battery safety charging control system, includes: In response to a charging request, a detection current pulse of preset amplitude is applied to the target lithium battery, voltage response data is collected, and the ohmic internal resistance and polarization internal resistance of the target lithium battery are calculated based on the voltage response data. When the polarization internal resistance does not exceed the preset polarization internal resistance threshold, the total internal resistance of the battery is calculated based on the ohmic internal resistance and the polarization internal resistance, the initial charging current is determined based on the total internal resistance of the battery, and the target lithium battery is charged with constant current using the initial charging current. Obtain the current ambient temperature and dynamically set the protection temperature threshold based on the total internal resistance of the battery and the current ambient temperature; During the constant current charging process, a charging state assessment is performed according to a preset assessment cycle. The rate of change of the current total internal resistance of the battery relative to the previous assessment cycle is calculated. The rate of change of the internal resistance, the current temperature rise rate of the target lithium battery, and the current charging voltage change rate are weighted and fused to obtain a comprehensive score. The charging state assessment includes applying a current perturbation to the target lithium battery to recalculate the current total internal resistance of the battery. The current charging current is adjusted based on the comprehensive score, and the adjustment range of the current charging current is constrained based on the current total internal resistance of the battery. The protection temperature threshold is updated based on the adjusted charging current and the current total internal resistance of the battery.

2. The method according to claim 1, characterized in that, The step of obtaining the current ambient temperature and dynamically setting the protection temperature threshold based on the total internal resistance of the battery and the current ambient temperature specifically includes: Obtain the current ambient temperature of the target lithium battery; The theoretical heat generation power is calculated based on the total internal resistance of the battery and the current charging current, and the theoretical temperature rise is calculated based on the preset thermal resistance coefficient. The ratio of the total internal resistance of the battery to a preset internal resistance benchmark value is calculated as the internal resistance growth factor. A temperature correction coefficient is calculated using a nonlinear decay function. The temperature correction coefficient decreases nonlinearly with the internal resistance growth factor. The protection temperature threshold is determined based on the current ambient temperature, the theoretical temperature rise, and the temperature correction factor.

3. The method according to claim 1, characterized in that, The step of performing a charging state assessment according to a preset assessment cycle during the constant current charging process, calculating the rate of change of the current total internal resistance of the battery relative to the previous assessment cycle, and weighting and fusing the rate of change of internal resistance, the current temperature rise rate of the target lithium battery, and the current charging voltage change rate to obtain a comprehensive score, specifically includes: During the constant current charging process, the stability of the current charging current is monitored according to a preset evaluation cycle. When the current charging current meets the preset stability condition, a current disturbance is applied to the target lithium battery and the current total internal resistance of the battery is measured. Calculate the rate of change of the current total internal resistance of the battery relative to the internal resistance of the previous evaluation period; Obtain the current temperature rise rate and the current charging voltage change rate of the target lithium battery; The weighting coefficient is dynamically adjusted based on the ratio of the internal resistance change rate to the current temperature rise rate. When the internal resistance change rate exceeds a preset threshold, the weighting coefficient of the current temperature rise rate is increased. The internal resistance change rate, the current temperature rise rate, and the current charging voltage change rate are weighted and fused to obtain the current comprehensive score; The current comprehensive score is weighted over time to obtain a cumulative risk score, which is then used as the comprehensive score.

4. The method according to claim 1, characterized in that, The steps of adjusting the current charging current based on the comprehensive score, constraining the adjustment range of the current charging current based on the current total internal resistance of the battery, and updating the protection temperature threshold based on the adjusted charging current and the current total internal resistance of the battery specifically include: The charging current adjustment amount is determined based on the comprehensive score, and the maximum allowable adjustment range is determined based on the internal resistance growth factor of the current total internal resistance of the battery relative to the preset internal resistance benchmark value. The change in charging power is calculated based on the adjusted charging current, the current heat dissipation capacity is estimated based on the current temperature rise rate, and the adjustment amount of the charging current is constrained within the maximum allowable adjustment range and the power upper limit corresponding to the current heat dissipation capacity to obtain the actual adjustment amount. The current charging current is adjusted according to the actual adjustment amount. Based on the adjusted charging current and the current total internal resistance of the battery, the theoretical heat generation power is calculated. The protection temperature threshold is updated according to the theoretical heat generation power and the current ambient temperature.

5. The method according to claim 4, characterized in that, After the step of updating the protection temperature threshold based on the adjusted charging current and the current total internal resistance of the battery, the method further includes: By applying a current perturbation to the target lithium battery, the current ohmic internal resistance and the current polarization internal resistance are calculated respectively. The polarization growth rate of the current polarization internal resistance is calculated over multiple consecutive evaluation periods, and the ohmic growth rate of the current ohmic internal resistance is also calculated. Calculate the growth rate dispersion between the polarization growth rate and the ohmic growth rate; When the growth rate dispersion exceeds a preset dispersion threshold, the constant current charging is switched to a constant voltage charging mode with the current charging voltage as the upper limit. In the constant voltage charging mode, the current polarization internal resistance continues to be monitored according to the preset evaluation cycle. When the current polarization internal resistance falls below the preset polarization internal resistance threshold, the constant current charging is resumed.

6. The method according to claim 1, characterized in that, After the step of updating the protection temperature threshold based on the adjusted charging current and the current total internal resistance of the battery, the method further includes: When the comprehensive score is within the preset warning range for multiple consecutive evaluation cycles, the constant current charging is paused and the system enters a resting phase. During the resting phase, the terminal voltage change of the target lithium battery is collected, and the transient voltage drop component and the gradually changing voltage fall component in the terminal voltage change are obtained. The transient voltage drop component corresponds to the voltage released by the ohmic internal resistance, and the gradually changing voltage fall component corresponds to the voltage released by the polarization effect relaxation. Calculate the polarization relaxation ratio of the slowly varying voltage drop component relative to the transient voltage drop component; The recovery charging current is determined based on the polarization relaxation ratio, and the constant current charging of the target lithium battery is re-executed with the recovery charging current. The protection temperature threshold is then reset based on the recovery charging current and the current total internal resistance of the battery.

7. The method according to claim 6, characterized in that, After the step of updating the protection temperature threshold based on the adjusted charging current and the current total internal resistance of the battery, the method further includes: If the battery temperature does not reach the protection temperature threshold, the constant current charging continues and the next evaluation cycle begins, until the battery temperature reaches the protection temperature threshold and charging stops.

8. A lithium battery safe charging control system, characterized in that, The lithium battery safe charging control system includes: one or more processors and a memory; the memory is coupled to the one or more processors, the memory is used to store computer program code, the computer program code includes computer instructions, and the one or more processors call the computer instructions to cause the lithium battery safe charging control system to perform the method as described in any one of claims 1-7.

9. A computer-readable storage medium comprising instructions, characterized in that, When the instruction is executed on the lithium battery safe charging control system, the lithium battery safe charging control system performs the method as described in any one of claims 1-7.

10. A computer program product, characterized in that, When the computer program product is run on the lithium battery safe charging control system, the lithium battery safe charging control system performs the method as described in any one of claims 1-7.

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