A charging end current closed-loop control method, system and battery management system

Abstract

This application discloses a closed-loop control method, system, and battery management system for end-of-charge current, belonging to the field of battery management technology. The method includes: system initialization and parameter pre-configuration; periodic acquisition of real-time battery status parameters; and decision-making. If the current state of charge (SOC) is greater than or equal to the switching threshold and the current highest single-cell voltage is less than the difference between the real-time current reduction point voltage and the preset voltage tolerance, then the voltage feedback closed-loop loop is activated. In the closed-loop control, the voltage deviation is calculated, and combined with the preset current value obtained through SOC lookup, the target current request value is calculated and output using a weighted fusion algorithm. Otherwise, open-loop control is executed, directly querying the current MAP table to output the request value. This solution solves the problems of charging delay, low efficiency, and safety risks caused by the decreased accuracy of SOC estimation using the ampere-hour integral method at the end of the charging process. It achieves optimized control by real-time compensation of SOC error through voltage deviation feedback.

Description

Technical Field

[0001] This invention relates to the field of battery management technology, specifically to a closed-loop control method, system, and battery management system for end-of-charge current. Background Technology

[0002] With the widespread application of lithium-ion battery technology in various fields, especially electric vehicles and energy storage systems, efficient and safe charging strategies are crucial. The currently commonly used method for calculating battery state of charge (SOC) is the ampere-hour integral method (Ah integral). This method estimates the remaining battery capacity percentage by integrating the charge and discharge current in real time. During charging, when the individual battery cell voltage has not yet reached the preset current reduction point (e.g., 4.2V / cell, designed to prevent overcharging), the battery management system (BMS) typically queries a preset current mapping table based on the current SOC value to request the corresponding charging current. This is an open-loop control logic based on a single SOC parameter.

[0003] However, existing technologies that heavily rely on SOC lookup tables have significant drawbacks. First, the ampere-hour integration method suffers from inherent accuracy degradation in the high SOC region. Due to the minute charging current at this stage, inherent noise and drift (e.g., ±0.5% error) in the sensor or current measurement loop are amplified, leading to an "inflated" calculated SOC value. This means the battery capacity appears high (e.g., 99%), while the actual capacity may only be 98%. The primary problem caused by this is prolonged charging time. The system continues charging with a tiny current request based on an incorrect SOC value, creating a "plateau" or "99% stagnation," significantly reducing efficiency towards the end of the charging process. Second, an inflated SOC can lead to misjudgments, such as incorrect estimates of the electric vehicle's range. More seriously, during the SOC stagnation phase, the battery remains in a low-current charging state for an extended period, potentially causing increased local polarization, overheating, and even lithium plating (lithium ion deposition on the graphite anode surface). This severely accelerates battery aging; studies show that frequent SOC stagnation can shorten battery cycle life by 10-15%. Therefore, how to overcome the low efficiency and safety hazards at the charging end caused by inaccurate SOC estimation is a technical problem that urgently needs to be solved in this field.

[0004] To address these issues, some existing technologies attempt to calibrate and optimize the ampere-hour integration algorithm, or supplement it with open-circuit voltage correction. However, these methods may require long periods of rest to obtain the open-circuit voltage, or lack robustness in high-dynamic usage scenarios, making real-time compensation difficult. Another approach relies solely on voltage thresholds for control. However, since battery voltage changes gradually across different states of charge (especially plateau periods), determining the current switching point based solely on voltage thresholds may not achieve optimal charging speeds and is difficult to avoid the interference of battery aging on voltage plateaus. Therefore, both control strategies that rely solely on SOC and those that rely solely on voltage have inherent limitations in charging end-point scenarios with high SOC, high precision, and high safety requirements.

[0005] In summary, existing SOC lookup-based charging control methods suffer from control failures at the end of the charging process due to inaccurate SOC calculations, leading to a series of chain reactions such as low charging efficiency, time delay effects, and accelerated battery aging. There is an urgent need for a new charging strategy that can overcome the limitations of a single parameter in the high SOC region and achieve more precise, efficient, and safe control. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing a closed-loop control method, system, and battery management system for the charging end current, in order to solve problems such as charging time delay, low efficiency, and potential safety risks caused by inflated battery SOC estimates at the end of the charging process.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, a closed-loop control method for charging end current is characterized by comprising the following steps: S1: Initialize and pre-configure the battery management system (BMS), including the SOC switching threshold, current MAP meter, and drop point reference voltage, and calculate the dynamic real-time drop point voltage based on the battery's current state of health (SOH). Specifically, in S1, the BMS is initialized and its parameters are pre-configured, including: S101: Load the core parameter table, which includes the current MAP table and the cell characteristic parameter table; wherein, the current MAP table is a two-dimensional relational table with SOC as the first index and battery temperature as the second index, used to store reference current values ​​under different operating conditions; the cell characteristic parameter table stores the current reduction point reference voltage, SOC switching threshold, voltage tolerance band, and plateau voltage and current parameters used to calculate the adjustment factor; S102: Perform dynamic configuration parameter calculation, including querying the current available SOH of the battery and calculating the real-time drop point voltage based on the product of the drop point reference voltage and the current battery SOH value.

[0008] S2: During the charging process, the real-time status parameters of the battery are periodically collected. The status parameters include the current highest single-cell voltage, charging current, operating temperature, and the real-time state of charge (SOC) of the battery calculated by the ampere-hour integration method. Specifically, S2 includes: S201: Sensor data reading, including: reading the individual cell voltage through the ADC circuit, scanning all individual cells in the cell to find the current highest individual cell voltage; reading the charging current value; reading data from multiple temperature sensors, selecting the maximum value or average value as the current operating temperature for temperature compensation; S202: The battery state of charge (SOC) is calculated using the ampere-hour integration method, and the integration efficiency is corrected based on the current operating temperature. Furthermore, the expression for the battery's state of charge (SOC) is as follows:

[0009] In the formula, Indicates the current number The state of charge of the battery at each sampling time, i.e., the current remaining percentage of battery charge; Indicates the previous ( The battery state of charge at each sampling time is used to calculate... The initial value or historical benchmark; This represents the current charging current value, i.e., the instantaneous current value measured at the current sampling moment; This indicates the time interval between two samplings; nominal capacity refers to the rated capacity specified by the battery at the time of manufacture.

[0010] Furthermore, the expression for the battery's state of charge (SOC) describes the basic principle of the ampere-hour integration method: the current remaining percentage of battery charge (SOC). ), equal to the percentage of remaining battery power at the previous moment ( Add (or subtract) the percentage of total battery capacity that was charged (or discharged) during the period from the previous moment to the current moment; and, based on the current operating temperature. Correcting the integral efficiency is a key optimization and necessary supplement to the ampere-hour integration method in practical applications; this is because: Temperature effect: The actual usable capacity and charge / discharge efficiency of the battery will change with temperature ( ) changes; at low temperatures, the battery's internal resistance increases, its activity decreases, and the actual charge or discharge capacity will be less than the theoretical integral value; specific correction methods: in order to obtain a more accurate SOC, the ( This part is usually multiplied by a temperature-dependent efficiency coefficient. The revised core computational idea becomes: ‌

[0011] in, It is a coefficient ≤ 1, which is based on the current battery temperature ( This is obtained through table lookup or formula, and is used to compensate for the loss of charging and discharging efficiency caused by temperature; during charging, It indicates the charging acceptance efficiency; during discharge, it indicates the discharge efficiency.

[0012] S203: Filter and determine the data obtained in steps S201 and S202.

[0013] Furthermore, the filtering and determination of the obtained data includes: determining the current highest single-unit voltage. Software filtering is used to suppress measurement noise; the calculated SOC is limited and sloped to prevent abnormal jumps; when the cell voltage is detected to enter the preset high voltage zone, the SOC update rate is weighted or slowed down according to the configuration to avoid stagnation at the end of charging due to low current, and the static OCV at this time is recorded, that is, the terminal voltage of the battery in the open circuit and fully rested state.

[0014] S3: Decision judgment, determine whether the current SOC is greater than or equal to the SOC switching threshold, and whether the current highest single-cell voltage is less than the combination of the difference between the real-time current reduction point voltage and a preset voltage tolerance. S4: In the closed-loop control process, if the judgment result of S3 is yes, then the voltage feedback closed-loop circuit is activated, using the deviation value between the real-time current reduction point voltage and the current highest voltage of the battery cell. As input, the target current request value is calculated by combining the current value obtained by querying the current MAP table through the current SOC. Specifically, if the judgment result of step S3 is yes, the voltage feedback closed-loop circuit is activated and the target current request value is calculated, which specifically includes: Calculate voltage deviation The Real-time drop point voltage Subtract the current highest single-cell voltage Its calculation expression is,

[0015] In the formula, This indicates the current highest single-cell voltage. Indicates the current decreasing voltage; The preset lookup charging current value for the current dropout point is obtained from the MAP table. Calculate the closed-loop adjustment term The current value obtained by querying the current MAP table through SOC ; when At that time, the total requested current is calculated using weighted fusion. The calculation expression is as follows:

[0016] In the formula, This indicates a pre-set adjustment factor; and This is a weighting coefficient, whose value or numerical relationship is used to balance the contribution of the current MAP meter reference value and the voltage deviation feedback term to the target current. The specific value is dynamically adjusted according to the SOC section, battery temperature, or charging stage, and satisfies... ; when If the individual cell voltage has exceeded or is close to the dropout point voltage, then the target current request value will be adjusted. The current is limited to a preset safe low current value to perform forced current reduction.

[0017] Furthermore, the weighting coefficients The corresponding value is between 0.6 and 0.9. The corresponding value is between 0.4 and 0.1, and In a specific implementation, the weighting coefficient , Possible forms: It is 0.7. It is 0.3.

[0018] S5: Apply safety boundary constraints to the target current request value, and output the constrained target current request value to the charging device to control the charging process; Specifically, in S5, a safety boundary constraint is applied to the target current request value, and the constrained target current request value is output to the charging device to control the charging process, specifically including: S501: Safety boundary check, calculates the target current request value. The minimum value is compared with the battery cell specifications, the maximum allowable current for temperature rise, and the maximum output capacity of the charging pile, and taken as the final output value. S502: The BMS will send a new target current command to the charging pile via CAN bus or power line carrier communication through the communication protocol. S503: Charging pile response. After receiving a new instruction, the charging pile adjusts the output current of its DC power module.

[0019] Specifically, if the judgment result in S3 is negative, open-loop control is executed. The current MAP table is queried based on the real-time SOC and the operating temperature, and the queried current value is directly output as the target current request value.

[0020] Secondly, based on the same inventive concept as the first aspect of this invention, a charging end current closed-loop control system is also provided, the system comprising: Input module: includes a voltage sensor for monitoring the voltage of individual battery cells, a current sensor for measuring the charging current, a temperature sensor for environmental compensation, and a user parameter interface for input voltage threshold and adjustment factor K; A data processing and decision-making module, electrically connected to the input module, is configured to: Store pre-configured parameters such as SOC switching threshold, current MAP meter, current drop point reference voltage, and adjustment factor K; It receives sensor data from the input module and calculates the real-time SOC of the battery based on the ampere-hour integration method; Execute the aforementioned decision judgment; Based on the decision-making results, select whether to execute closed-loop or open-loop control, and calculate the target current request value; The output module, connected to the data processing and decision-making module, is used to send the target current request value to the charging pile.

[0021] Thirdly, a battery management system is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the charging end current closed-loop control method described in the first aspect of the present invention.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects: 1. Solving the charging "platform stagnation" problem caused by artificially high SOC at the charging end: When the SOC is artificially high, the system does not blindly follow the open-loop lookup table of a single SOC, but instead uses real-time voltage deviation as negative feedback for compensation. When the actual single-cell voltage is not yet close to the current reduction point, the system will actively increase the current request, effectively eliminating the current stagnation caused by SOC error and significantly shortening the charging time at the charging end. Experimental data shows that this method can shorten the charging time by 10% to 30%.

[0023] 2. Enhanced robustness and adaptability of control: A fusion algorithm combining SOC weights (e.g., 0.7) and voltage closed-loop weights (e.g., 0.3) is adopted. This retains the macroscopic guidance of SOC change trends on charging behavior while compensating for insufficient SOC accuracy at the end through real-time feedback from the voltage closed loop. Simultaneously, the current drop point voltage is dynamically adjusted based on the battery's SOH, adapting to the characteristics of batteries with different aging levels, thus improving the algorithm's universality and safety.

[0024] 3. Achieve smooth transition and safety protection: The algorithm seamlessly switches to voltage closed-loop mode when the conditions are met (high SOC, low voltage); when the voltage reaches the current reduction point (ΔV ≤ 0), the system immediately performs forced current reduction, switches to minimal current or stops charging, effectively preventing overcharging and protecting battery safety.

[0025] 4. Easy to implement and low cost: The core is software algorithm improvement, without the need to add new hardware sensors. It can be implemented through software upgrades on existing battery management system (BMS) hardware platforms, with low implementation cost, making it easy to promote and apply on a large scale in electric vehicles, consumer electronics, energy storage and other fields.

[0026] 5. Energy saving and consumption reduction benefits: By optimizing the charging current trajectory, the charging time caused by unreasonable delays is reduced, which not only improves the user experience, but also effectively reduces the standby losses of the power grid and BMS during the charging process, which has positive significance for energy saving and emission reduction in large-scale applications.

[0027] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic flowchart of a closed-loop control method for charging terminal current in one embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1: In one embodiment, please refer to Figure 1A closed-loop control method for charging terminal current is provided, the method comprising the following steps: Step S1: Initialize and pre-configure the battery management system (BMS), including the SOC switching threshold, current MAP meter, and drop point reference voltage, and calculate the dynamic real-time drop point voltage based on the battery's current state of health (SOH). Step S2: During the charging process, the real-time status parameters of the battery are periodically collected. The status parameters include the current highest single-cell voltage, charging current, operating temperature, and the real-time state of charge (SOC) of the battery calculated by the ampere-hour integration method. Step S3: Decision judgment, determine whether the current SOC is greater than or equal to the SOC switching threshold, and whether the current highest single-cell voltage is less than the combination of the difference between the real-time current reduction point voltage and a preset voltage tolerance. Step S4: Closed-loop control process. If the judgment result of S3 is yes, then the voltage feedback closed-loop circuit is activated, using the deviation between the real-time current reduction point voltage and the current highest voltage of the battery cell. As input, the target current request value is calculated by combining the current value obtained by querying the current MAP table through the current SOC. Step S5: Apply safety boundary constraints to the target current request value, and output the constrained target current request value to the charging device to control the charging process; If the judgment result in S3 is negative, then open-loop control is executed, and the current MAP table is queried according to the real-time SOC and the operating temperature, and the queried current value is directly output as the target current request value. Repeat steps S1 to S5 until charging is complete.

[0032] In this embodiment, step S1, the initialization and parameter pre-configuration of the battery management system (BMS), specifically includes: Step S101: Load the core parameter table, including the current MAP table and the cell characteristic parameter table, wherein: The current MAP table is a two-dimensional relational table with the battery state of charge (SOC) as the first index and the battery temperature as the second index, and presets reference current values ​​for various operating conditions; for example, when the SOC is 30% and the temperature is 25°C, the corresponding charging current is 1.5C; when the SOC is 95%, the corresponding current will be significantly reduced to 0.2C. The cell characteristic parameter table stores key thresholds and coefficients used for decision-making, including: the current drop point reference voltage ( ): Standard charging cutoff voltage for individual cells; SOC switching threshold ( ): The SOC threshold used to start the closed-loop voltage control, typically 95%; Voltage tolerance band ( This is used to prevent frequent closed-loop intervention caused by small voltage fluctuations, such as ±0.05V; plateau voltage and current parameters ( , ), used for dynamically calculating adjustment factors This is used to quantify the current adjustment corresponding to a unit voltage change.

[0033] Furthermore, the adjustment factor The expression is,

[0034] In the formula, and These represent the voltage and current parameters during the plateau period, respectively. and These represent the preset lookup table charging current values ​​for the current drop point voltage and the current drop point voltage, respectively.

[0035] Step S102: Calculate dynamic configuration parameters, including the current available SOH query and the determination of real-time reduced current voltage. ,in: The current available SOH query is obtained from the BMS storage unit by retrieving the current battery health status (SOH) estimated through long-term statistics or algorithm models. The determination of real-time reduced current voltage It is calculated according to a formula, the expression of which is:

[0036] In the formula, Indicates the reference voltage at the current drop point; This indicates the current state of health (SOH) of the battery, a smart threshold that dynamically adjusts according to the battery's health. It's a key indicator used to measure the degree of performance degradation of the battery relative to its brand-new condition at the factory. It's usually expressed as a percentage, with 100% representing a brand-new battery. The lower the value, the more severe the battery aging. For example, for the current cell, the current dropout point is 4.2V. 0.98 = 4.116V. This enables the dropout point to be intelligently adjusted downwards as the battery ages, protecting it.

[0037] In this embodiment, step S2 includes: Step S201: Sensor data reading, including: reading the individual cell voltage through the ADC circuit, scanning all individual cells in the cell, and finding the highest current individual cell voltage. Read the charging current value Read data from multiple temperature sensors and select either the maximum or average value as the current operating temperature. , used for temperature compensation; Step S202: Calculate the battery state of charge (SOC) using the ampere-hour integration method, and then adjust it according to the current operating temperature. Correct the integration efficiency; Furthermore, the expression for the battery's state of charge (SOC) is as follows:

[0038] In the formula, Indicates the current number The state of charge of the battery at each sampling time, i.e., the current remaining percentage of battery charge; Indicates the previous ( The battery state of charge at each sampling time is used to calculate... The initial value or historical benchmark; This represents the current charging current value, i.e., the instantaneous current value measured at the current sampling moment; This indicates the time interval between two samplings; nominal capacity refers to the rated capacity specified by the battery at the time of manufacture.

[0039] Furthermore, the expression for the battery's state of charge (SOC) describes the basic principle of the ampere-hour integration method: the current remaining percentage of battery charge (SOC). ), equal to the percentage of remaining battery power at the previous moment ( Add (or subtract) the percentage of total battery capacity that was charged (or discharged) during the period from the previous moment to the current moment; and, based on the current operating temperature. Correcting the integral efficiency is a key optimization and necessary supplement to the ampere-hour integration method in practical applications; this is because: Temperature effect: The actual usable capacity and charge / discharge efficiency of the battery will change with temperature ( ) changes; at low temperatures, the battery's internal resistance increases, its activity decreases, and the actual charge or discharge capacity will be less than the theoretical integral value; specific correction methods: in order to obtain a more accurate SOC, the ( This part is usually multiplied by a temperature-dependent efficiency coefficient. The revised core computational idea becomes: ‌

[0040] in, It is a coefficient ≤ 1, which is based on the current battery temperature ( This is obtained through table lookup or formula, and is used to compensate for the loss of charging and discharging efficiency caused by temperature; during charging, It indicates the charging acceptance efficiency; during discharge, it indicates the discharge efficiency.

[0041] Step S203: Filter and determine the data obtained in steps S201 and S202.

[0042] Furthermore, the filtering and determination of the obtained data includes: determining the current highest single-unit voltage. Software filtering is used to suppress measurement noise; the calculated SOC is limited and sloped to prevent abnormal jumps; when the cell voltage is detected to enter the preset high voltage zone, the SOC update rate is weighted or slowed down according to the configuration to avoid stagnation at the end of charging due to low current, and the static OCV at this time is recorded, that is, the terminal voltage of the battery in the open circuit and fully rested state.

[0043] In this embodiment, steps S3 and S4 are explained in detail as follows: In step S3, it is determined whether the current SOC is greater than or equal to the SOC switching threshold. Furthermore, the determination of whether voltage closed-loop activation is required is based on the combination of whether the current highest single-cell voltage is less than the difference between the real-time current drop point voltage and a preset voltage tolerance. Condition A: The current battery state of charge (SOC) is greater than the preset SOC switching threshold. ,Right now: ; Condition B: Current highest single-cell voltage Less than the current voltage drop Subtract the voltage tolerance band value ,Right now: .

[0044] In step S4, based on the judgment condition in step S3, the process of determining whether to activate the voltage feedback closed-loop circuit is performed, including: If conditions A and B are met simultaneously, it is determined that charging has entered the end stage. The SOC may be inaccurate, and the voltage feedback closed loop needs to be activated to jump to the closed loop adjustment path. Otherwise, it is determined that the charging is in a plateau or initial stage, the SOC accuracy is controllable, and the system jumps to the standard lookup table path.

[0045] Furthermore, the aforementioned jump to the standard table lookup path, i.e., the traditional open-loop path, specifically includes: Based on the current battery state of charge and current operating temperature Consult the 'Current MAP Table' to find the current value stored in the corresponding cell; this represents the standard answer for this operating condition. ; Will The final target current request is sent to the charging station, i.e. .

[0046] Furthermore, during the process of jumping to the standard lookup path, a smooth transition method is selected. If exiting from the closed loop, a brief gradual transition process can be set to avoid current jumps.

[0047] Furthermore, the requirement to activate the voltage feedback closed-loop circuit and jump to the closed-loop adjustment path specifically includes: Calculate voltage deviation The Real-time drop point voltage Subtract the current highest single-cell voltage Its calculation expression is,

[0048] In the formula, This indicates the current highest single-cell voltage. Indicates the current decreasing voltage; The preset lookup charging current value for the current dropout point is obtained from the MAP table. Calculate the closed-loop adjustment term The current value obtained by querying the current MAP table through SOC ,when At that time, the total requested current is calculated using weighted fusion. The calculation expression is as follows:

[0049] In the formula, This indicates a pre-set adjustment factor; and This is a weighting coefficient, whose value or numerical relationship is used to balance the contribution of the current MAP meter reference value and the voltage deviation feedback term to the target current. Its value is dynamically adjusted according to the SOC section, battery temperature, or charging stage, and satisfies... .

[0050] Furthermore, when If the cell voltage has exceeded or is close to the descent point voltage, it indicates that the charging is very close to saturation, and the target current request value will be adjusted accordingly. The current is limited to a preset safe low current value to perform forced current reduction.

[0051] Furthermore, the weighting coefficients The corresponding value is between 0.6 and 0.9. The corresponding value is between 0.4 and 0.1, and In a specific implementation, the weighting coefficient , Possible forms: It is 0.7. It is 0.3.

[0052] In this embodiment, step S5 involves applying a safety boundary constraint to the target current request value and outputting the constrained target current request value to the charging device to control the charging process, including: Step S501: Safety boundary check, calculate the target current request value The minimum value is compared with the battery cell specifications, the maximum allowable current for temperature rise, and the maximum output capacity of the charging pile, and taken as the final output value. Step S502: Send via communication protocol. The BMS will send a new target current command to the charging pile via either CAN bus or power line carrier communication. Step S503: Charging pile response. After receiving the new instruction, the charging pile adjusts the output current of its DC power module.

[0053] In this embodiment, the closed-loop control method for charging end current also involves fault modes and anomaly handling, specifically including: If a sensor fails and invalid or out-of-limit data is detected from a critical sensor, the system will immediately exit the voltage closed loop and switch back to a conservative lookup mode that relies on a single available sensor, while illuminating the fault indicator light. Logical timeout: To prevent the closed-loop process from entering an infinite loop due to unexpected events, a timeout timer is set. If charging remains in the high SOC (>95%) stage for more than a preset value (e.g., 1 hour) without completion, the system may determine that there is an internal algorithm failure or battery malfunction and will stop charging. In the event of a communication interruption, if the communication between the BMS and the charging pile is interrupted more than a certain number of times or for a certain period of time, the system should trigger an emergency stop procedure and disconnect the relay.

[0054] The above implementation method, through specific steps such as data acquisition, decision-making, fusion computing, and output control, as well as practical application parts such as initialization parameter settings, data preprocessing, and fault handling mechanisms, makes the entire solution highly operable. The robustness and safety of this solution, beyond addressing core technical issues (artificially high SOC, slow charging), are demonstrated through weighting coefficients, protection mechanisms, and temperature compensation.

[0055] Example 2: A closed-loop control system for end-of-charge current, the system comprising: Input module: includes a voltage sensor for monitoring the voltage of individual battery cells, a current sensor for measuring the charging current, a temperature sensor for environmental compensation, and a user parameter interface for input voltage threshold and adjustment factor K; A data processing and decision-making module, electrically connected to the input module, is configured to: Store pre-configured parameters such as SOC switching threshold, current MAP meter, current drop point reference voltage, and adjustment factor K; It receives sensor data from the input module and calculates the real-time SOC of the battery based on the ampere-hour integration method; Execute the aforementioned decision judgment; Based on the decision-making results, select whether to execute closed-loop or open-loop control, and calculate the target current request value; The output module, connected to the data processing and decision-making module, is used to send the target current request value to the charging pile.

[0056] Furthermore, in this embodiment, the data processing and decision-making module is also configured to automatically exit the voltage closed-loop control mode and switch to a conservative lookup table control mode based on valid data when the sensor data is detected to be invalid or exceeds a preset safety threshold, while triggering a fault indication.

[0057] Example 3: In this embodiment, a battery management system is provided, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the charging end current closed-loop control method of the present invention.

[0058] 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; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A charge termination current closed loop control method, characterized by, Includes the following steps: S1: Initialize and pre-configure the battery management system (BMS), including the SOC switching threshold, current MAP meter, and drop point reference voltage, and calculate the dynamic real-time drop point voltage based on the battery's current state of health (SOH). S2: During the charging process, the real-time status parameters of the battery are periodically collected. The status parameters include the current highest single-cell voltage, charging current, operating temperature, and the real-time state of charge (SOC) of the battery calculated by the ampere-hour integration method. S3: Decision judgment, determine whether the current SOC is greater than or equal to the SOC switching threshold, and whether the current highest single-cell voltage is less than the combination of the difference between the real-time current reduction point voltage and a preset voltage tolerance. S4: closed-loop control process, if the judgment result of S3 is yes, activate the voltage feedback closed-loop circuit, to obtain the deviation value between the real-time current reduction point voltage and the current highest voltage of the battery monomer As input, combine the current value obtained by querying the current SOC of the current SOC, and obtain the target current request value by calculation; S5: Apply safety boundary constraints to the target current request value, and output the constrained target current request value to the charging device to control the charging process; If the judgment result in S3 is negative, then open-loop control is executed. The current MAP table is queried based on the real-time SOC and the operating temperature, and the queried current value is directly output as the target current request value.

2. The charge terminal current closed loop control method of claim 1, wherein, Step S1, which initializes and pre-configures the BMS parameters, specifically includes: S101: Load the core parameter table, which includes the current MAP table and the cell characteristic parameter table; wherein, the current MAP table is a two-dimensional relational table with SOC as the first index and battery temperature as the second index, used to store reference current values ​​under different operating conditions; the cell characteristic parameter table stores the current reduction point reference voltage, SOC switching threshold, voltage tolerance band, and plateau voltage and current parameters used to calculate the adjustment factor; S102: Perform dynamic configuration parameter calculation, including querying the current available SOH of the battery and calculating the real-time drop point voltage based on the product of the drop point reference voltage and the current battery SOH value.

3. The charge terminal current closed loop control method of claim 1 or 2, wherein, Step S2 involves periodically collecting real-time state parameters of the battery during the charging process. These state parameters include the current highest single-cell voltage, charging current, operating temperature, and the real-time state of charge (SOC) calculated using the ampere-hour integration method, as obtained through real-time monitoring. S201: Sensor data reading, including: reading the individual cell voltage through the ADC circuit, scanning all individual cells in the cell to find the current highest individual cell voltage; reading the charging current value; reading data from multiple temperature sensors, selecting the maximum value or average value as the current operating temperature for temperature compensation; S202: The battery state of charge (SOC) is calculated using the ampere-hour integration method, and the integration efficiency is corrected based on the current operating temperature. S203: Filter and determine the data obtained in steps S201 and S202.

4. The charge terminal current closed loop control method of claim 3, wherein, In step S202, the formula for calculating the real-time SOC of the battery using the ampere-hour integration method is as follows: In the formula, Indicates the current number The state of charge of the battery at each sampling time, i.e., the current remaining percentage of battery charge; Indicates the previous ( The battery state of charge at each sampling time is used to calculate... The initial value or historical benchmark; This represents the current charging current value, i.e., the instantaneous current value measured at the current sampling moment; Indicates the time interval between two samples; Nominal capacity is the rated capacity of the battery at the time of shipment. is a coefficient of 1 ≤ a ≤ 1, which is obtained by table lookup or formula according to the current battery temperature (T) ) and is used to compensate for the loss of charge and discharge efficiency due to temperature; when charging, represents the charge acceptance efficiency; when discharging, it represents the discharge efficiency.

5. The charge termination current closed loop control method of claim 1, wherein, In step S4, if the judgment result of step S3 is yes, the voltage feedback closed-loop circuit is activated and the target current request value is calculated, specifically including: Computing voltage deviation , the Real-time drop point voltage Subtracting current highest cell voltage The calculation expression is, wherein represents the current highest cell voltage, represents the current downflowing cell voltage; The preset table charging current value of the drop point table current is obtained by querying the MAP table , the closed loop adjustment term is calculated , the current value obtained by querying the SOC current MAP table ; when At that time, the total requested current is calculated using weighted fusion. The calculation expression is: In the formula, This indicates a pre-set adjustment factor; and These are weighting coefficients, whose values ​​or relationships are used to balance the contribution of the current MAP meter reference value and the voltage deviation feedback term to the target current, and satisfy the following conditions: ; when If the individual cell voltage has exceeded or is close to the dropout point voltage, then the target current request value will be adjusted. The current is limited to a preset safe low current value to perform forced current reduction.

6. The charging end current closed-loop control method as described in claim 5, characterized in that, The weighting coefficient The value ranges from 0.6 to 0.9, and the weighting coefficient... The value range is from 0.1 to 0.4, and satisfies the following condition: .

7. The charging end current closed-loop control method as described in claim 1, characterized in that, Step S5 involves applying safety boundary constraints to the target current request value and outputting the constrained target current request value to the charging device to control the charging process. Specifically, this includes: S501: Safety boundary check, compares the calculated target current request value with the cell specifications, the maximum allowable current for temperature rise, and the maximum output capacity of the charging pile, and takes the minimum value as the final output value; S502: The BMS will send a new target current command to the charging pile via CAN bus or power line carrier communication through the communication protocol. S503: Charging pile response. After receiving a new instruction, the charging pile adjusts the output current of its DC power module.

8. A closed-loop control system for charging terminal current, characterized in that, The system is used to execute a closed-loop control method for charging end current as described in any one of claims 1 to 7, the system comprising: Input module: includes a voltage sensor for monitoring individual battery cell voltage, a current sensor for measuring charging current, a temperature sensor for environmental compensation, and a user parameter interface for input voltage threshold and adjustment factor K; A data processing and decision-making module, electrically connected to the input module, is configured to: Store pre-configured parameters such as SOC switching threshold, current MAP meter, current drop point reference voltage, and adjustment factor K; It receives sensor data from the input module and calculates the real-time SOC of the battery based on the ampere-hour integration method; Execute the aforementioned decision judgment; Based on the decision-making results, select whether to execute closed-loop or open-loop control, and calculate the target current request value; The output module, connected to the data processing and decision-making module, is used to send the target current request value to the charging pile.

9. The charging end current closed-loop control system as described in claim 8, characterized in that, The data processing and decision-making module is also configured to automatically exit the voltage closed-loop control mode and switch to a conservative lookup table control mode based on valid data when the sensor data is detected to be invalid or exceeds a preset safety threshold, and at the same time trigger a fault indication.

10. A battery management system, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of a charging end current closed-loop control method as described in any one of claims 1 to 7.

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