CN116699433A - Battery cell monitoring method and device, battery management system and electronic equipment - Google Patents

Abstract

The embodiment of the application discloses a method and a device for monitoring cell expanding gas, a storage medium and electronic equipment, wherein the method comprises the following steps: when the voltage of the target battery cell is in a specified voltage interval, carrying out electrochemical excitation on the target battery cell, determining a standing voltage difference after the electrochemical excitation, acquiring a characteristic impedance Rc value of the target battery cell, determining an Rc growth rate based on the characteristic impedance Rc value, and monitoring the inflation condition of the target battery cell based on the Rc growth rate and the standing voltage difference of the target battery cell.

Description

A battery cell monitoring method, device, battery management system and electronic equipment

technical field

The present application relates to the field of battery technology, and in particular to a battery cell monitoring method, device, storage medium and electronic equipment.

Background technique

Battery inflation is one of the common battery failure situations at present. The battery inflation will lead to an increase in the internal pressure of the battery, which will cause the risk of failure of the battery packaging. The battery inflation may also cause deformation of the end product and further cause safety risks. Based on this, it is necessary to monitor the inflation of the battery during use;

At present, physical sensors are usually added on the surface of the battery cell or the inflation state of the battery cell is detected through the change of the internal resistance of the battery cell. However, physical sensors are easily interfered by external factors and are expensive, and the change of internal resistance cannot rule out factors such as material aging to directly reflect the state of cell inflation.

Contents of the invention

The purpose of this application is to provide a simple and efficient battery flatulence monitoring method, device, storage medium and electronic equipment. The technical solution is as follows:

In the first aspect, the present application provides a battery monitoring method, the method comprising:

When the voltage of the target cell is within the specified voltage interval, perform electrochemical excitation on the target cell, determine the static voltage difference after electrochemical excitation, and obtain the characteristic impedance Rc value of the target cell, wherein the specified voltage interval is a cut-off voltage multiplier interval taking the cut-off voltage of the target cell as a reference, and the cut-off voltage multiplier interval is 0.8 to 0.95;

Determine the Rc growth rate based on the characteristic impedance Rc value;

Monitor the inflation of the target cell based on the Rc growth rate and the static voltage difference of the target cell.

In the above solution, the characteristic impedance Rc value change caused by the interface side reaction or flatulence can be extracted from the electrical signal feedback through electrochemical excitation. At the same time, when the cell expands due to interface side reactions, the polarization of the cell increases, and its static voltage difference will change accordingly, so that the static voltage difference after electrochemical excitation can be combined with the change of the characteristic impedance Rc value Realize the detection of the flatulence of the battery cell.

In a feasible implementation manner, performing electrochemical excitation on the target cell, and determining the resting voltage difference after electrochemical excitation includes:

Obtain electrochemical excitation parameters, which include reference excitation magnification, excitation duration and resting time;

Perform electrochemical excitation on the target cell based on the reference excitation ratio, and keep the excitation duration;

At the end of the electrochemical excitation, record the target cell resting start voltage corresponding to the target cell, and after the resting time, the target cell resting end voltage corresponding to the target cell is based on the target cell resting start voltage. The voltage and the target cell rest end voltage determine the rest voltage difference after electrochemical excitation.

In the above scheme, the electrochemical excitation parameters are used to electrochemically stimulate the target cell, and based on the initial voltage of the target cell at rest recorded at the end of the electrochemical excitation, and the target voltage recorded after a certain period of rest, The static end voltage of the cell can accurately calculate the static voltage difference, so as to accurately assist in monitoring the flatulence of the target cell and reduce the monitoring error.

In a feasible implementation manner, the electrochemical excitation is charge excitation or discharge excitation; the reference excitation rate is 0.5C-1.5C, the excitation duration is 10s-30s, and the standing time is 60s-240s.

In the above scheme, by setting the preferred reference excitation magnification, excitation duration and resting time, as a preferred means of cell monitoring, the effect of electrochemical excitation can be further improved, thereby improving measurement accuracy.

In a feasible implementation, the flatulence of the target cell is monitored based on the Rc growth rate and the static voltage difference, including:

Obtain the reference cell, perform a first-order linear fitting process on the Rc growth rate of the reference cell and the expansion rate of the reference cell, and obtain a prediction model of the impedance expansion rate;

Determine the target cell expansion rate based on the Rc growth rate and impedance expansion rate prediction model of the target cell; obtain the first detection result based on the target cell expansion rate, and obtain the second detection result based on the static voltage difference;

Based on the first detection result and the second detection result, the cell inflation condition of the target cell is determined.

In the above scheme, the first detection result is determined by performing cell expansion detection from the Rc growth rate dimension based on the characteristic impedance Rc value change, and the second detection result is performed from the resting voltage difference dimension. In the first detection result Based on the combination of the second detection result of the static voltage difference dimension after electrochemical excitation, the precise monitoring of the cell inflation of the cell is further realized, and the monitoring accuracy is improved.

In a feasible implementation manner, the first detection result is obtained based on the target cell expansion rate, the second detection result is obtained based on the static voltage difference, and the cell of the target cell is determined based on the first detection result and the second detection result. Gas conditions, including:

Detecting whether the expansion rate of the target cell is greater than a first growth rate threshold to obtain a first detection result;

Detecting whether the static voltage difference is greater than the first static voltage difference threshold, and obtaining a second detection result;

If the first detection result is that the expansion rate of the target cell is greater than the first growth rate threshold and the second detection result is that the resting voltage difference is greater than the first resting voltage difference threshold, then it is determined that the target cell belongs to the cell inflation state;

If the first detection result is that the expansion rate of the target cell is less than or equal to the first growth rate threshold and/or the second detection result is that the resting voltage difference is less than or equal to the first resting voltage difference threshold, then it is determined that the target cell belongs to the cell normal status.

In the above solution, the cell expansion rate dimension is detected based on the set first growth rate threshold, and the static voltage difference dimension is detected based on the set first static voltage difference threshold. Based on the first detection result and the second The test results can accurately determine the battery inflation situation, which enriches the means of battery monitoring;

In a feasible implementation manner, if the target cell is in the state of cell flatulence, step-down control is performed on the charging cut-off voltage corresponding to the target cell;

In the above scheme, a cell control method based on the cell monitoring method for step-down control processing is proposed. Using the cell control method to perform step-down control processing on the target cell can effectively prolong the service life of the cell

In a feasible implementation manner, step-down control processing is performed on the charging cut-off voltage corresponding to the target cell, including:

If the target cell expansion rate belongs to the first expansion rate range and the resting voltage difference is greater than the first resting voltage difference threshold, stepping down the charging cut-off voltage corresponding to the target cell based on the voltage drop value;

Determine the next cell expansion rate based on the Rc growth rate, and obtain the next resting voltage difference;

If the expansion rate of the next battery cell belongs to the first expansion rate interval and the next resting voltage difference is greater than the first resting voltage difference threshold, the step of performing a step-down control process on the charging cut-off voltage corresponding to the target cell;

If the next cell expansion rate belongs to the second expansion rate range and the resting voltage difference is greater than the first resting voltage difference threshold, a cell replacement suggestion is output.

In the above scheme, in the case of battery expansion, the service life of the battery can be effectively extended, and rapid disaster recovery warning based on battery expansion can be realized in a timely and effective manner.

In a feasible implementation manner, the reference cell is obtained, and the Rc growth rate of the reference cell and the expansion rate of the reference cell are subjected to a first-order linear fitting process, and the impedance expansion rate prediction model obtained also includes:

When the voltage of the reference cell is in the specified voltage range, perform electrochemical excitation on the reference cell, measure the reference cell expansion value of the reference cell and obtain the reference characteristic impedance Rc value of the reference cell;

Determine the reference Rc growth rate based on the reference characteristic impedance Rc value, and determine the reference cell expansion rate based on the reference cell expansion value;

Based on the reference cell expansion rate and the reference Rc growth rate, the first-order linear fitting process is performed to obtain the impedance expansion rate prediction model.

In the above scheme, the impedance expansion rate prediction model is established in advance for the Rc growth rate and the cell expansion rate. Using the impedance expansion rate prediction model can accurately predict the current cell expansion rate based on the Rc growth rate, and the prediction method is convenient. Optimization of the core monitoring process. The predictive effect of the impedance expansion rate prediction model is better, and rapid monitoring can be realized.

In a feasible implementation manner, the method also includes the following preprocessing steps:

Obtain the cell capacity parameters corresponding to multiple cells and the open circuit voltage deviation at the same SOC, and select a reference cell from multiple cells based on the cell capacity parameters and open circuit voltage deviation;

The reference battery is configured with a specified temperature range environment, and the reference battery is cyclically charged with the reference charging rate and the reference number of cycles to obtain the reference battery after the battery is pretreated.

In the above scheme, a preprocessing method for the reference cells used in the first-order linear model is proposed. By performing preprocessing steps on multiple reference cells, reference can be made from the dimensions of open circuit voltage deviation and cell capacity parameters. Cell screening and cyclic charging of reference cells can screen out high-quality reference cells, while fully activating the performance of the cells and reducing the additional introduction of reference cells in the modeling process of the first-order linear model. The error can reduce the modeling data fluctuation.

In a feasible implementation, the cell capacity parameter is the cell design capacity value and the actual capacity fluctuation value, and the reference cell is selected from multiple reference cells based on the cell capacity parameter and the open circuit voltage deviation, including:

Select reference cells from multiple cells based on cell capacity parameters and open circuit voltage deviation, including:

Select at least one candidate battery cell whose design capacity value of the battery cell is greater than the reference design capacity value and whose actual capacity fluctuation value is smaller than the reference capacity fluctuation value;

Select the reference cell whose open circuit voltage deviation is less than the deviation threshold from the candidate cells.

In the above scheme, the screening of high-quality reference cells is realized through the cell design capacity value, actual capacity fluctuation value and open circuit voltage deviation, and suitable and standard cells can be screened out for subsequent modeling process.

In the above solution, by setting an appropriate designated voltage interval, as a preferred or recommended implementation of cell monitoring, the effect of electrochemical excitation can be further improved, thereby improving measurement accuracy.

In the second aspect, the embodiment of the present application provides a cell monitoring device, which includes:

The excitation module is used to electrochemically stimulate the target cell when the voltage of the target cell is within a specified voltage range, determine the static voltage difference after the electrochemical excitation, and obtain the characteristic impedance Rc value of the target cell;

A monitoring module, configured to determine the Rc growth rate based on the characteristic impedance Rc value;

The monitoring module is used to monitor the flatulence of the target battery based on the Rc growth rate and the static voltage difference of the target battery.

In a third aspect, an embodiment of the present application provides a battery management system, which is characterized in that it is connected to a battery, the battery includes at least one battery cell, and the battery management system is configured to execute the above method steps.

In a fourth aspect, an electronic device is characterized in that it includes: a body, a battery management system, and a battery connected to the battery management system, and the battery includes at least one battery cell;

The battery is used to power the body;

The battery management system is used to execute the above method steps.

In a fifth aspect, a computer storage medium stores a plurality of instructions, and the instructions are adapted to be loaded by a processor and execute the above method steps.

In a sixth aspect, an embodiment of the present application provides a computer program product, the computer program product stores at least one instruction, and the at least one instruction is loaded by a processor to execute the above method steps.

Other features and advantages of the present application will be set forth in the ensuing description and, in part, will be apparent from the description, or can be learned by implementing the embodiments of the present application. The objectives and other advantages of the application may be realized and attained by the structure particularly pointed out in the written description and appended drawings.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present application. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

FIG. 1 is a schematic flow chart of a cell monitoring method provided in an embodiment of the present application;

Fig. 2 is a schematic flow chart of flatulence monitoring provided by the embodiment of the present application;

FIG. 3 is a schematic diagram of a linear fitting scenario provided by an embodiment of the present application;

Fig. 4 is a schematic flow chart of the preprocessing steps of a reference cell provided in the embodiment of the present application;

FIG. 5 is a graph of a step-down control provided by an embodiment of the present application;

Fig. 6 is a comparative schematic diagram of battery monitoring provided by the embodiment of the present application;

Fig. 7 is a schematic structural diagram of a cell monitoring device provided in an embodiment of the present application.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the application with reference to the drawings in the embodiments of the application. Apparently, the described embodiments are only some of the embodiments of the application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

In the description of the present application, it should be understood that the terms "first", "second" and so on are used for descriptive purposes only, and should not be understood as indicating or implying relative importance. In the description of the present application, it should be noted that, unless otherwise specified and limited, "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally also includes unlisted steps or units, or optionally further includes For other steps or units inherent in these processes, methods, products or devices. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application in specific situations. In addition, in the description of the present application, unless otherwise specified, "plurality" means two or more. "And/or" describes the association relationship of associated objects, indicating that there may be three types of relationships, for example, A and/or B may indicate: A exists alone, A and B exist simultaneously, and B exists independently. The character "/" generally indicates that the contextual objects are an "or" relationship.

In the related art, the physical sensor is used to detect the expansion state of the battery cell, and there are the following problems: 1) additional hardware costs need to be added; 2) the introduction of the sensor requires a targeted design of the battery compartment of the device to accommodate the battery required for the inflation detection. Hardware, and for consumer products (mobile phones, computers, battery compartments, etc.), due to the compact size, the monitoring solution using physical sensors does not meet the requirements of the application scenario; 3) The sensor is easily triggered by the temperature and vibration of the battery during use False alarms, when the device is dropped or collided, it may also cause the sensor to shift or fall off, making the detection signal no longer reliable or the detection invalid.

It can be seen that there are certain limitations in battery cell monitoring in the related art.

Through the creative work of the applicant, it was found that the expansion of the battery cell is mainly caused by the expansion of the battery cell, and the expansion of the battery cell mainly includes two types of expansion: 1) The volume change of the active particles of the electrode material due to lithium ion deintercalation during the process of deintercalation of lithium , the expansion of this part is reversible expansion, which usually expands in the charging state and recovers in the discharging state, which will not cause obvious changes in the overall volume of the cell; 2) the other is the expansion caused by the side reaction process at the electrode interface, and Side reactions inevitably lead to an increase in the internal resistance of the cell, and the generation of gas further affects the contact between the electrode and the electrolyte, thereby further increasing the internal resistance.

In one or more embodiments of the present application, in order to improve or even completely solve the limitations of related technologies, at least adopt: when the voltage of the target cell is within a specified voltage range, perform electrochemical excitation on the target cell to determine the electrochemical The static voltage difference after excitation, and obtain the characteristic impedance Rc value of the target cell; by applying electrochemical excitation to the target cell, extract the characteristic impedance Rc value caused by the interface side reaction or flatulence from the electrical parameter signal feedback At the same time, considering the expansion of the battery due to the side reaction at the interface, the overall polarization of the battery will also increase accordingly. After the voltage of the target cell reaches the cut-off voltage, the depolarization time will be prolonged. After standing for a certain period of time, the static voltage difference of the voltage will also change accordingly. The change of the characteristic impedance Rc value and the static voltage difference can characterize the flatulence state of the battery cell to a certain extent. Based on and combined with the resting voltage difference after electrochemical excitation. It is possible to monitor the flatulence of the target cell.

Among them, the characteristic impedance Rc value can be understood as the physical quantity that hinders the flow of current generated by the electrochemical reaction inside the cell and the characteristics of the electrode material, which is not the same technical concept as the internal resistance of the battery.

The present application will be described in detail below in conjunction with specific embodiments.

In one embodiment, as shown in FIG. 1 , a battery cell monitoring method is proposed, which can be realized by relying on a computer program and can run on a battery cell monitoring device based on the von Neumann system. The computer program can be integrated in the application, or run as an independent utility application. Specifically, the cell monitoring method includes:

S102: When the voltage of the target cell is within the specified voltage range, perform electrochemical excitation on the target cell, determine the static voltage difference after electrochemical excitation, and obtain the characteristic impedance Rc value of the target cell, wherein the specified The voltage interval is a cut-off voltage multiplier interval taking the cut-off voltage of the target cell as a reference, and the cut-off voltage multiplier interval is 0.8-0.95;

The executor of the embodiment of the present application may be a battery management system (Battery Management System, BMS). The battery management system can manage the battery cells of the battery, for example, it can manage various parameters of the battery cells, such as voltage, current and other parameters. , and can also manage the battery charging and discharging process. The battery management system may be electrically connected to the battery;

Schematically, the battery management system (Battery Management System, BMS) monitors the voltage of the target cell during charging or discharging, and when the voltage of the target cell is within a specified voltage range, electrochemically stimulates the target cell to determine The static voltage difference after electrochemical excitation, and at the same time obtain the characteristic impedance Rc value of the target cell.

Further, when the voltage of the target cell is within a specified voltage range, perform at least one round of electrochemical excitation on the target cell periodically or in real time, and obtain the resting voltage after the electrochemical excitation of the target cell difference, and the characteristic impedance Rc value of the target battery; for example, for the characteristic impedance Rc value of the target battery, the characteristic impedance Rc value of the target battery can be obtained at interval preset periods or in real time, so as to facilitate subsequent determination of the target The inflation of the battery cell.

Optionally, when the voltage of the target cell is in the specified voltage range, at least one round of electrochemical excitation can be performed, and the characteristic impedance Rc value and the static voltage difference ΔV of the target cell for each round of electrochemical excitation can be recorded;

Assuming that the i-th round of electrochemical excitation is currently performed on the target cell, when recording the electrochemical excitation, the cell initial voltage V ₀ and (the current that ends the electrochemical excitation) the end current I, the excitation duration of the electrochemical excitation is x seconds, Record the static start voltage Vs of the target cell after the electrochemical excitation (the target cell's static start voltage and the excitation end voltage), stand for a certain period of a second, and in the "stand for a certain period of a second" Then record the resting end voltage V _r ;

Schematically, the characteristic impedance Rc value of the target cell at this time satisfies the following formula:

Rc=(Vs–V ₀ )/I

Schematically, the static voltage difference ΔV satisfies the following formula:

ΔV=Vs- _Vr

Schematically, since the value of ΔV reflects the polarization state of Li ion diffusion in part of the cell, when the cell expands due to interface side reactions, the polarization state of the diffusion part is also reflected, so the value of ΔV Abnormalities are introduced into the cell monitoring link in this application, based on the Rc growth rate and the static voltage difference ΔV to realize the judgment of the combined cell flatulence;

It can be understood that when the voltage of the target cell is in the specified voltage range, the target cell is periodically electrochemically excited for multiple rounds, and its characteristic impedance Rc value can usually be multiple, and its static voltage difference ΔV can be one or more. The specified voltage interval can be set in advance according to the voltage interval of the battery application system (such as the battery ternary nickel-cobalt-manganese-graphite system), and the interval can be 0.8-0.95 of the highest cut-off voltage designed by the battery;

Optionally, the electrochemical excitation is a charging excitation or a discharging excitation. The charging excitation can be understood as charging the cell at a specified charging current, and the discharging excitation can be understood as discharging the target cell at a specified charging voltage.

In a feasible implementation manner, the electrochemical excitation is performed on the target cell, and the process of determining the static voltage difference after electrochemical excitation can be as follows:

A2: Acquire electrochemical excitation parameters, which include reference excitation ratio, excitation duration and resting time;

Schematically, the electrochemical excitation parameters of the electrochemical excitation can be set in advance, and the set electrochemical excitation parameters can be directly obtained in the actual application stage;

A4: Perform electrochemical excitation on the target cell based on the reference excitation ratio, and keep the excitation duration;

A6: At the end of the electrochemical excitation, record the static start voltage of the target cell corresponding to the target cell. The starting voltage and the target cell resting end voltage determine the resting voltage difference after electrochemical excitation.

Schematically, taking the electrochemical excitation as the charging excitation as an example, the obtained electrochemical excitation parameters can be the reference charging rate a1, the charging duration b1, and the standing time c1 after charging; further, when the cell voltage In the specified voltage range, regularly charge the cell with an appropriate current at the reference charge rate a1, and keep the charging duration b1, and record the charging start voltage V0 and end current I during each round of electrochemical excitation , the duration of continuous charging b1, record the starting voltage Vs of the target cell after the charging excitation, the standing time c1 after the charging is completed, and record the ending voltage V _r after the static;

Further, the characteristic impedance Rc value and the static voltage difference ΔV of the target cell are further calculated, and by analogy, the characteristic impedance Rc value and the static voltage difference of the target cell can be obtained for each round of electrochemical excitation ΔV;

Optionally, the reference excitation ratio is 0.5C to 1.5C;

Optionally, the incentive duration is 10s to 30s;

Optionally, the standing time is 60s-240s.

It should be noted that in the above example, the specific values such as the reference excitation magnification of 0.5C to 1.5C, the excitation duration of 10s to 30s, and the rest period of 60s to 240s cannot be understood as limitations on this application. . That is to say, the reference excitation magnification can be any value in other intervals besides 0.5C~1.5C, such as 0.4C~1.6C, 0.3C~1.3C, etc.; In addition to 30s, it can also be any value in other intervals, such as 10s~40s, 8s~20s, etc.; and, in addition to 60s~240s, the standing time can also be any value in other intervals, such as 50s～100s, 80s～250s, etc.; therefore, the ranges corresponding to the reference excitation magnification, excitation duration, and resting time in the above examples cannot be understood as limitations on this application;

S104: Determine the Rc growth rate based on the characteristic impedance Rc value;

After obtaining the aforementioned one or more characteristic impedance Rc values, determine the Rc growth rate based on the obtained characteristic impedance Rc values;

When determining the Rc growth rate, it may be to determine the growth rate of the obtained Rc value relative to the first obtained Rc value, that is, if the obtained Rc value is the first obtained Rc value, then the corresponding Rc growth rate is 0, if the obtained Rc value is not the first obtained Rc value, then the Rc growth rate is the growth ratio of the obtained Rc value relative to the first obtained Rc value;

Among them, the calculation process of Rc growth rate is [(Rci-Rc1)/Rc1]*100%, Rci represents the Rc value obtained for the i-th time, the value of i is a positive integer, and Rc1 represents the Rc value obtained for the first time.

Optionally, the battery management system can pre-store the reference characteristic impedance Rc value recorded before the cell leaves the factory (which can be used as the Rc value obtained for the first time), that is, the Rc base value. The actual application stage can be based on the current measured characteristic impedance Rc Value and reference characteristic impedance Rc value, directly calculate Rc growth rate.

In actual application scenarios, when the target cell is charged to the specified voltage range (such as 80-95% of the highest cut-off voltage), it can trigger Rc data and ΔV value extraction, record the continuously read Rc value, and determine the Rc growth rate ;

S106: Monitor the inflation of the target battery based on the Rc growth rate and the static voltage difference of the target battery.

After obtaining the Rc growth rate and the static voltage difference, the flatulence of the current target cell can be monitored based on the Rc growth rate and the static voltage difference impedance expansion rate prediction model;

In a feasible implementation, the impedance expansion rate prediction model may be a relationship table model including the impedance expansion rate corresponding to the reference cell expansion rate and "specified Rc growth rate and specified static voltage difference". In practical applications, Based on the impedance expansion rate relationship table model, the cell expansion rate corresponding to the current "Rc growth rate and static voltage difference" can be found, and the cell expansion rate can represent the flatulence of the cell;

Among them, the impedance expansion rate relationship table model can be: when the voltage of the reference cell is in the specified voltage range, perform electrochemical excitation on the reference cell, determine the reference static voltage difference corresponding to the reference cell after electrochemical excitation, and measure The reference cell expansion value of the reference cell and the reference characteristic impedance Rc value of the reference cell are obtained to determine the reference Rc growth rate, and the reference cell expansion rate is determined based on the reference cell expansion value;

Because, in the model building stage, several sets of impedance expansion rate mappings of "reference cell expansion rate-reference Rc growth rate and reference static voltage difference" can be determined based on the above-mentioned method, and correlation processing is performed based on multiple sets of impedance expansion rate mapping, which is convenient It is possible to establish a resistance expansion rate relationship table model.

It should be noted that "when the voltage of the reference cell is within the specified voltage range, perform electrochemical excitation on the reference cell, determine the reference resting voltage difference corresponding to the reference cell after electrochemical excitation, and obtain the reference voltage of the reference cell. The reference Rc growth rate for determining the characteristic impedance Rc value" can refer to the relevant interpretations of the aforementioned determination of the static voltage difference, the characteristic impedance Rc value, and the Rc growth rate. The execution steps are similar and will not be repeated here;

In a feasible implementation, the impedance expansion rate prediction model may be a model created based on a machine learning model and trained using the reference cell expansion rate and the reference Rc growth rate, as follows:

Sample data collection: collect a large number of impedance expansion rate samples, which include the reference static voltage difference and the reference Rc growth rate obtained based on the aforementioned reference cells;

Sample data annotation: mark the reference cell expansion value measured above for the impedance-voltage difference sample, and use the reference cell expansion value as the label of the impedance-voltage difference sample;

Model forward propagation training: Create an initial impedance expansion rate prediction model based on a machine learning model, input impedance-voltage difference samples into the initial impedance expansion rate prediction model for at least one round of model training, and obtain the corresponding prediction voltage for impedance-voltage difference samples Core expansion rate;

Model backpropagation fine-tuning: During each round of model forward propagation training, the model loss is calculated based on the model loss calculation formula based on the predicted cell expansion rate and the sample label-reference cell expansion rate, and the initial impedance expansion rate based on the model loss Adjust the model parameters of the prediction model until the initial impedance expansion rate prediction model meets the model training end condition, and obtain the trained impedance expansion rate prediction model;

Optionally, the predicted cell expansion rate and the sample label-reference cell expansion rate can be used to calculate the model loss using the set model loss function, such as the model loss function can be a Euclidean distance loss function, a cross-entropy loss function, a hinge loss function, etc. wait.

Optionally, the model training end condition of the model may include, for example, that the value of the loss function is less than or equal to a preset loss function threshold, the number of iterations reaches a preset threshold, and the like. The specific conditions for ending the training of the model can be determined based on the actual situation, and are not specifically limited here.

It should be noted that the machine learning models involved in one or more embodiments of this specification include but are not limited to convolutional neural network (Convolutional Neural Network, CNN) model, deep neural network (Deep Neural Network, DNN) model, recurrent neural network (Recurrent Neural Networks, RNN), model, embedding (embedding) model, gradient boosting decision tree (Gradient Boosting Decision Tree, GBDT) model, logistic regression (Logistic Regression, LR) model and other machine learning models or one or more of fitting.

Schematically, a model training method of the impedance expansion rate prediction model based on a machine learning model is proposed. Based on this method, a trained impedance expansion rate prediction model can be obtained, and the impedance expansion rate prediction model can be adapted to complex cells. Monitor the scene and accurately calculate the cell expansion rate. The model has good robustness.

In the embodiment of the present application, the characteristic impedance Rc value change caused by the interface side reaction or flatulence can be extracted from the electrical signal feedback through electrochemical excitation. At the same time, when the cell expands due to interface side reactions, the polarization of the cell increases, and its static voltage difference will change accordingly, so that the static voltage difference after electrochemical excitation can be combined with the change of the characteristic impedance Rc value Realize the detection of the flatulence of the battery cell.

Please refer to FIG. 2 . FIG. 2 is a schematic flow chart of flatulence monitoring proposed by the present application. specific:

S202: Determine the cell expansion rate based on the Rc growth rate;

In a feasible embodiment, a first-order linear fitting process can be performed based on the reference cell expansion rate and the reference Rc growth rate in advance to obtain a first-order linear model, and the first-order linear model can be used as the impedance expansion rate prediction model;

In the practical application stage, the cell expansion rate can be obtained based on the Rc growth rate using the impedance expansion rate prediction model.

The following explanations can be referred to for the model establishment process of the impedance expansion rate prediction model based on the first-order linear model:

B2: When the voltage of the reference cell is in the specified voltage range, perform electrochemical excitation on the reference cell, measure the reference cell expansion value of the reference cell and obtain the reference characteristic impedance Rc value of the reference cell;

B4: Determine the reference Rc growth rate based on the reference characteristic impedance Rc value, and determine the reference cell expansion rate based on the reference cell expansion value;

The reference Rc growth rate refers to the growth rate of the reference characteristic impedance Rc value; the process of "determining the reference Rc growth rate based on the reference characteristic impedance Rc value" can refer to the interpretation of the aforementioned step "determining the Rc growth rate based on the characteristic impedance Rc value", the two are similar , which will not be repeated here.

The reference cell expansion rate refers to the growth rate of the reference cell expansion value, and the reference cell expansion value can be understood as the thickness S of the reference cell;

Schematically, when the electrochemical excitation is performed on the reference cell, the electrochemical excitation can be multiple rounds, so that multiple reference cell expansion values can be obtained. After obtaining the aforementioned one or more reference cell expansion values , the reference cell expansion rate can be determined based on the acquired reference cell expansion value S;

When determining the reference cell expansion rate, it may be to determine the growth rate of the acquired reference cell expansion value S relative to the first acquired reference cell expansion value S, that is, if the acquired reference cell expansion value S is the reference cell expansion value S obtained for the first time, then the corresponding reference cell expansion rate is 0, if the obtained reference cell expansion value S is the reference cell expansion value S not obtained for the first time, then the The reference cell expansion (growth) rate is the growth ratio of the acquired reference cell expansion value relative to the first acquired reference cell expansion value;

Among them, the calculation process of the reference cell expansion rate S% is [(Si-S1)/S1]*100%, Si represents the S value obtained for the i-th time, the value of i is a positive integer, and S1 represents the first obtained The Rc value.

B6: Based on the reference cell expansion rate and the reference Rc growth rate, a first-order linear fitting process is performed to obtain a first-order linear model. When actually applied to cell monitoring, the first-order linear model can be used as a prediction model for impedance expansion rate. The first-order linear model can be understood as a model for Rc growth rate and cell expansion rate;

Specifically, according to the reference Rc growth rate R% and the reference cell expansion rate S% measured in each round, perform correlation processing on multiple sets of "reference Rc growth rate R% and reference cell expansion rate S%" data, and Perform first-order linear fitting processing to obtain the relationship between R% and S%;

Optionally, with Rc% as the independent variable and S% as the dependent variable, the first-order linear model can be expressed as follows:

S%=a ₁ *Rc%+b ₁

Optionally, with S% as the independent variable and Rc% as the dependent variable, the first-order linear model can be expressed as follows:

Rc%= _a2 *S%+ _b2

In the cell design stage, the reference cell will continue to expand by setting a certain working condition. In the different expansion stages of the reference cell (usually according to the cell thickness, that is, the expansion range of the reference cell expansion rate direction, it can be set at 0 -20% stage for modeling), set a certain interval with time or number of cycles to continuously record the reference cell expansion rate, and record at the same time set certain conditions in the specified voltage range (electrochemical excitation parameters, such as reference excitation magnification, excitation duration , standing time, etc.) to perform one or more rounds of electrochemical excitation to obtain the corresponding Rc value, and use the data of the cell state before the reference cell leaves the factory as the base value, and the base value is to calculate the Rc based on the base value The growth value Rc%, and the growth value S% of the expansion value, establish a first-order linear fitting between Rc% and S%;

The initial n sets of data are processed to obtain the initial first-order linear model, and the Rc% data obtained in each subsequent round are substituted into the initial first-order linear model to calculate S%, and compared with the measured S%, if the calculated predicted S% and The measured actual S% prediction error, if the prediction error is less than or equal to the error threshold (such as 5%), there is no need to update the first-order linear model, if the prediction error is greater than the error threshold, then the measured Rc% and S% will be added to the data set , to re-fit the first-order linear model to obtain a new fitting relationship, and iteratively update the first-order linear model; use the collected first-order linear model as the prediction model of impedance expansion rate, and the Rc base recorded before the battery leaves the factory The value is embedded into the BMS of the battery management system so that it can be called during actual use.

S204: Obtain a first detection result based on the target cell expansion rate, and obtain a second detection result based on the static voltage difference;

The first detection result can be understood as the result of cell expansion detection from the Rc growth rate dimension, and based on the cell expansion rate, it can be preliminarily judged whether the cell expands;

The first detection result can be understood as the result of cell expansion detection from the static voltage difference dimension, and the first detection result can be further optimized from the static voltage difference dimension to remove the detection error from the Rc growth rate dimension.

In a feasible implementation manner, it may be detected whether the target cell expansion rate is greater than the first growth rate threshold to obtain the first detection result;

Schematically, a threshold for the cell expansion rate can be set in advance, which is also the first growth rate threshold. For example, the first growth rate threshold can be customized to 10%. At this time, the first detection result is the cell expansion Whether the rate is greater than the result of the first growth rate of 10%.

In a feasible implementation manner, it is detected whether the resting voltage difference is greater than the first resting voltage difference threshold, and a second detection result is obtained;

Schematically, the threshold for the static voltage difference can be set in advance, which is also the first static voltage difference threshold, the first static voltage difference threshold can be customized, and the second detection result is whether the static voltage difference is results in greater than the first resting voltage difference threshold.

S206: Based on the first detection result and the second detection result, determine the battery inflation condition of the target battery cell.

It can be understood that based on the first detection result and the second detection result, it is jointly judged whether the battery cell is inflated, that is, to determine the cell inflation of the battery cell.

In a feasible implementation manner, if the first detection result is that the expansion rate of the target cell is greater than the first growth rate threshold and the second detection result is that the resting voltage difference is greater than the first resting voltage difference threshold, then the target cell is determined It belongs to the state of cell inflation;

If the first detection result is that the expansion rate of the target cell is less than or equal to the first growth rate threshold and/or the second detection result is that the resting voltage difference is less than or equal to the first resting voltage difference threshold, then it is determined that the target cell belongs to the cell normal status.

Exemplarily, in order to better understand the implementation steps of the present application, the following examples explain the impedance expansion rate prediction model and the first resting voltage difference threshold, as follows:

Select a batch of fresh batteries with a design capacity such as 5000mAh that have been manufactured within one month, and screen the reference batteries whose actual capacity and design capacity deviation is within the specified capacity range (such as 0%-0.35%). Modeling data collection. Select specific conditions to accelerate the expansion of the cell and data acquisition, and perform a cycle test on the cell at a constant temperature of 45°C (the temperature shown here is only an example, and the temperature can be [10°C, 80°C]) , the test condition is that the voltage of the reference cell is charged/discharged in a specified voltage range of 3.0-4.2V for multiple rounds of charge/discharge excitation, and the reference cell is charged/discharged at intervals (Cycle) (such as every 50CL (cycle)), Extract the reference characteristic impedance Rc value of the reference cell and the reference cell expansion value to determine the reference cell expansion rate S% with the reference cell expansion value,

The specific charging/discharging excitation process is as follows:

(1) 0.5C CC/CV to 4.2V, Rest 5min: That is, use 0.5c rate to charge the reference cell with constant current/constant voltage, so that the voltage of the reference cell reaches 4.2V, and rest for 5min;

(2) 0.5C DC to 3V, Rest 5min: that is, discharge the reference cell with a rate of 0.5c, so that the voltage of the reference cell reaches 3V, and rest for 5min;

(3) Cycle (1) and (2) until the Swelling (flatulence rate) reaches the specified threshold (such as 16%), and measure the cell expansion value S every 5cls;

At the same time, when the voltage of the reference cell reaches the specified voltage interval corresponding to the cut-off voltage (such as the 80-95% interval), the aforementioned "model establishment process of the impedance expansion rate prediction model" process is applied, and the selected rate in this example is 0.5C , the excitation time is 12s, and the resting time is 240s;

Calculate the reference characteristic impedance Rc value: Rc=(Vs–V0)/I

Calculate the reference static voltage difference ΔV value: ΔV=Vs–Vr

Select the Rc obtained for the first time (close to the Fresh state) as the basic value of Rc, and the increase of the Rc value obtained in each subsequent round relative to the basic value of Rc is Rc%; similarly, select the thickness S obtained for the first time (close to the Fresh state) As the basic value of S, the increment of the thickness S value acquired in each subsequent round relative to the basic value of S is S%. In this way, the practical application of multiple sets of "reference Rc growth rate R% and reference cell expansion rate S%" is determined. As shown in the figure, Figure 3 is a schematic diagram of a linear fitting scene. "Growth rate R% and reference cell expansion rate S%" data are correlated, and first-order linear fitting is performed, and the first-order linear model between Rc% and S% is obtained as the impedance expansion rate prediction model, as shown in Figure 3 The prediction model of the resistance expansion rate between Rc% and S% is S%=0.0437Rc%+3.1318.

The first-order linear fitting process is to process the initial n sets of data to obtain the initial first-order linear model, and then substitute the Rc% data obtained in each subsequent round into the initial first-order linear model to calculate S%, and compare it with the measured S%, that is, the reference voltage Comparing the core expansion rate S%, if the prediction error between the predicted S% and the measured reference cell expansion rate S% is calculated, if the prediction error is less than or equal to the error threshold (such as 5%), there is no need to update the first-order linearity model, if the prediction error is greater than the error threshold, the measured Rc% and the reference cell expansion rate S% are added to the data set, and the first-order linear model is re-fitted to obtain a new fitting relationship. Iterative update; the collected first-order linear model is used as the impedance expansion rate prediction model, and the impedance expansion rate prediction model and the Rc base value recorded before the battery leaves the factory are embedded in the battery management system BMS, so that they can be called during actual use.

For the setting of the first static voltage difference threshold, it can be selected that when the expansion rate S% of the reference cell reaches the set target working condition, the target working condition can be that when S% reaches the target value (such as 10%), the expansion Abnormal, so that when the reference cell expansion rate S% reaches the target value, the current reference static voltage difference is obtained as the first static voltage difference threshold.

In the embodiment of the present application, during monitoring, the first detection result is determined by performing cell expansion detection from the Rc growth rate dimension based on the characteristic impedance Rc value change, and the second detection result is performed from the static voltage difference dimension. On the basis of the first detection result, combined with the second detection result of the static voltage difference dimension after electrochemical excitation, it further realizes the accurate monitoring of the cell inflation state of the battery cell and improves the monitoring accuracy.

In one or more embodiments of the present application, the cell monitoring method may further include a preprocessing step;

Please refer to FIG. 4 . FIG. 4 is a schematic flowchart of the pretreatment steps of a reference cell. specific:

S302: Obtain the cell capacity parameters corresponding to the multiple cells and the open circuit voltage deviation at the same SOC, and select a reference cell from the multiple cells based on the cell capacity parameters and the open circuit voltage deviation;

The cell capacity parameter may be the cell design capacity value, the cell actual capacity value, and the cell capacity parameter may also include the difference between the cell design capacity value and the cell actual capacity value, that is, the actual capacity fluctuation value. The design capacity value of the battery cell can be directly determined in the design stage of the reference cell, and the actual capacity value of the cell can be obtained by instrument measurement after the production of the reference cell is completed;

Optionally, the cell capacity parameter is the cell design capacity value and the actual capacity fluctuation value,

In a feasible implementation manner, selecting a reference cell from multiple cells based on cell capacity parameters and open-circuit voltage deviation may be as follows:

Select at least one candidate battery cell whose design capacity value of the battery cell is greater than the reference design capacity value and the actual capacity fluctuation value is smaller than the reference capacity fluctuation value from multiple cells, and select a reference cell whose open circuit voltage deviation is less than the deviation threshold value from the candidate cells. Batteries.

Schematically, cells with similar capacities are selected from multiple cells, specifically, the reference cells are selected from the two dimensions of the cell design capacity value and the open circuit voltage deviation of the cell, and are screened out through the preprocessing step The subsequent establishment of the impedance expansion rate prediction model of the reference cell has a higher degree of fitting and a more accurate model;

For example, select a battery cell whose design capacity value > reference design capacity value - 3000mAh and whose open-circuit voltage deviation of the reference cell is less than 10mV under the same SOC (state of charge).

The open circuit voltage deviation can be understood as the difference between the design open circuit voltage of the reference cell and the actual open circuit voltage. The smaller the open circuit voltage deviation is, the more stable the selected cell is, and it is more conducive to obtaining an accurate first-order linear model in the future.

S304: Configure the environment of a specified temperature range for the reference battery, perform cycle charging processing on the reference battery with the reference charging rate and the reference number of cycles, and obtain the reference battery after the pretreatment of the battery.

For the reference cell, in the preprocessing process, the reference cell can be configured with a specified temperature range environment, and the reference cell can be cycle-charged at the preset reference charging rate, and the number of cycle charging processing is the preset reference The number of cycles, which can fully activate the performance of the cell to reduce the number of subsequent first-order linear model modeling.

For example, the specified temperature range environment can be a specified temperature environment of "35 degrees -45 degrees", specifically, the reference battery can be placed in a high and low temperature box of "35 degrees -45 degrees", and the reference charging rate can be preset One of the magnifications in "0.1-0.2C" performs cycle charging treatment on the reference battery, and the number of cycle charging treatment is the reference number of cycles: 10 times, so as to fully activate the performance of the battery cell, and further, you can also compare the reference Whether the attenuation range of the cell capacity after the aforementioned cyclic charging treatment relative to the design capacity value is smaller than the target attenuation range (such as 0.1%), so as to reduce modeling data fluctuations.

In one or more embodiments of the present application, a preprocessing method for the reference cells used in the impedance expansion rate prediction model is proposed. By performing preprocessing steps on multiple reference cells, the open circuit voltage deviation, The cell capacity parameter dimension is used to screen reference cells, and the reference cells can be recharged cyclically, so that high-quality reference cells can be screened out, and at the same time, the performance of the cells can be fully activated, reducing the resistance expansion rate during the modeling process of the prediction model. The additional error introduced by referring to the factors of the cell itself can reduce the fluctuation of the modeling data.

In one or more embodiments of the present application, a cell control method is proposed after monitoring the flatulence of the cell to determine that the cell belongs to the cell flatulence state, specifically as follows:

After the cell monitoring device performs the step of monitoring the flatulence of the target cell based on the Rc growth rate and the static voltage difference of the target cell, if the target cell belongs to the cell flatulence state, the charging cut-off voltage corresponding to the target cell Perform step-down control processing.

In a feasible implementation manner, the process of the cell monitoring device performing step-down control on the charging cut-off voltage corresponding to the target cell may be as follows:

B2: If the target cell expansion rate belongs to the first expansion rate range and the resting voltage difference is greater than the first resting voltage difference threshold, then step down the charging cut-off voltage corresponding to the target cell based on the voltage drop value;

The voltage drop value can be understood as the voltage adjustment value that is set in advance to reduce the charging cut-off voltage after determining that the target battery cell belongs to the cell inflation state;

For example, assuming that the voltage drop value can be set to 50mv, during the charging process of the target cell, after it is determined that the target cell belongs to the cell flatulence state, the charging cut-off voltage is adjusted for the charging process of the cell, and the voltage drop value is used as a reference to reduce charging. cut-off voltage.

B4: Determine the next cell expansion rate based on the Rc growth rate, and obtain the next resting voltage difference;

After stepping down the charging cut-off voltage corresponding to the target cell based on the voltage drop value, the Rc growth rate is continuously monitored, and the next recorded cell expansion rate is determined based on the Rc growth rate;

B6: If the expansion rate of the next battery cell belongs to the first expansion rate range and the next resting voltage difference is greater than the first resting voltage difference threshold, then perform the step of stepping down the charging cut-off voltage corresponding to the target cell;

Optionally, the first expansion rate range may be set to 15%-20%;

Exemplarily, as shown in Figure 5, Figure 5 is a graph of a step-down control involved in this specification, the abscissa in Figure 5 is the number of cycle charging (Cycle NO.), and the ordinate is the battery cell Swelling, after the cell monitoring device performs the step of monitoring the inflation of the target cell based on the Rc growth rate and the static voltage difference, if the target cell is in the state of cell inflation, the strategy of reducing the cut-off voltage is triggered, As shown in Figure 5, four groups of cells were selected for testing, which were the cells corresponding to Example 1-1, the cells corresponding to Example 1-2, the cells corresponding to Example 1-3, and the cells corresponding to Example 1-3. For the cells corresponding to Examples 1-4, the 4 groups of cells respectively use the curve types shown in Figure 5 to characterize the charging process: the cell expansion rate (Swelling ) changes with the number of charging cycles (Cycle NO. in Figure 5 indicates the number of charging cycles); when the calculated Rc growth rate S%>10%, and the static voltage difference reaches the threshold value, the cut-off voltage is triggered, and the first round of cut-off Use when the voltage is reduced by 50mV; continuously monitor the next Rc growth rate S% and the next static voltage difference. When S%>15%, and the next static voltage difference reaches the threshold, the second stage of step-down is triggered, and the cut-off voltage is lowered again When using 50mV, the reduced value is 100mv. The cell expansion rate was suppressed, reaching 20% after 50 charging cycles.

As a comparison, the cell in Figure 5 does not take any control measures after obtaining the S% information, as shown in Figure 6, which is a schematic diagram of a comparison of cell monitoring, and the abscissa in Figure 6 is the number of cycle charging (Cycle NO .), and the ordinate is the cell expansion rate (Swelling) of the cell. Figure 6 shows that under the condition of 55 degrees high temperature charging cycle, compared with the comparison chart without control measures in Figure 5, 4 groups of the same model are also selected The batteries are tested, respectively, the batteries corresponding to Comparative Example 1-1, the batteries corresponding to Comparative Example 1-2, the batteries corresponding to Comparative Example 1-3 and the batteries corresponding to Comparative Example 1-4 , These 4 groups of batteries of the same type do not take any control measures, and the S% of the batteries reaches more than 20% after 30 charging cycles. It can be seen that after it is determined that the battery cell is in the state of battery cell inflation, the battery control method in this manual can also be used correspondingly to extend the service life of the battery cell.

B8: If the next battery cell expansion rate belongs to the second expansion rate range and the next resting voltage difference is greater than the first resting voltage difference threshold, output a battery replacement suggestion.

The second expansion rate interval is the threshold set for cell monitoring. When the expansion rate of the next cell reaches the second expansion rate interval, the cell may fail at this time;

Schematically, when it is detected that the next cell expansion rate of the cell falls into the second expansion rate range, a cell replacement suggestion may be output. For example, the second expansion rate interval may be 20%-100%. When the next cell expansion rate of the battery cell reaches 20% and the static voltage difference is greater than the first static voltage difference threshold, a cell replacement suggestion may be output.

It can be understood that the first expansion rate interval and the second expansion rate interval can be customized based on actual application conditions, which are not limited here.

In one or more embodiments of this specification, a cell control method based on a cell monitoring method is proposed. Using this cell control method can effectively prolong the service life of the cell. In the case of cell expansion, The battery control method can be used to timely and effectively realize rapid disaster recovery and early warning based on battery expansion.

Based on the same inventive concept, the embodiment of the present application also provides a battery management system (BMS), which is connected to the battery and used for managing the battery. The battery management system is used to receive information from the battery and various external interfaces, analyze and process the information, and issue execution instructions to complete battery charging, discharging, protection, equalization, fault detection and fault warning, etc., to ensure the normal and high efficiency of the battery , reasonable and safe operation. The battery management system can realize on-line monitoring of the cell inflation in the battery. For example, when the voltage of the cell is within the specified voltage range, the target cell can be electrochemically stimulated to determine the resting voltage after electrochemical excitation. difference, and obtain the characteristic impedance Rc value of the target cell, determine the Rc growth rate based on the characteristic impedance Rc value, and monitor the inflation of the target cell based on the Rc growth rate and the static voltage difference of the target cell.

Among them, BMS can be mainly divided into three parts of closed-loop feedback: information collection, information analysis and processing, and output decision-making execution instructions. For information collection, BMS needs to monitor the state of the battery in real time, and various sensors are needed to collect physical parameters such as voltage, current, and temperature of the battery cell. Information analysis and processing means that after the BMS collects relevant information, it needs to analyze and process the information to determine the actions to be taken. Outputting decision-making execution instructions means that the BMS outputs decision-making execution instructions to an interactive object (such as a charging device) interacting with it through an external interaction interface.

The battery management system can adopt an existing battery management system. For example, for devices such as notebook computers and electric vehicles, the battery management system is a battery management system used in current devices, and its structure is well known in the art. No further description here.

The cell monitoring principle and technical effects provided by the embodiment of the battery management system are the same as those of the foregoing method embodiments. For a brief description, for those not mentioned in the embodiments of the battery management system, reference may be made to the corresponding content in the foregoing method embodiments.

Based on the same inventive concept, an embodiment of the present application further provides an electronic device, the electronic device includes a main body, a battery management system, and a battery connected to the battery management system, and the battery includes at least one battery cell. The battery is used to supply power to the main body; the battery management system is used to implement the above-mentioned cell inflation detection method to realize online monitoring of the cell inflation. The electronic device may be a notebook computer, a tablet computer, a smart phone, and the like. It can be understood that the electronic device is not limited thereto, and may also be an electric device equipped with a power battery, for example, it may be an electric vehicle, such as an electric bicycle, an electric motorcycle, an electric car, and the like.

The cell monitoring device provided by the embodiment of the present application will be described in detail below with reference to FIG. 7 . It should be noted that the cell monitoring device shown in Figure 7 is used to execute the method of the embodiments shown in Figures 1 to 6 of the present application. For the convenience of description, only the parts related to the embodiments of the present application are shown. For technical details not disclosed, please refer to the embodiments shown in FIGS. 1 to 6 of this application.

Please refer to FIG. 7 , which shows a schematic structural diagram of a cell monitoring device according to an embodiment of the present application. The cell monitoring device 1 can be implemented as all or a part of the user terminal through software, hardware or a combination of the two. According to some embodiments, the cell monitoring device 1 includes an excitation module 11 and a monitoring module 12, specifically for:

The excitation module 11 is used to electrochemically stimulate the target cell when the voltage of the target cell is within a specified voltage range, determine the static voltage difference after the electrochemical excitation, and obtain the characteristic impedance Rc value of the target cell;

Monitoring module 12, for determining the Rc growth rate based on the characteristic impedance Rc value;

The monitoring module 12 is configured to monitor the inflation of the target battery based on the Rc growth rate and the static voltage difference of the target battery.

Optionally, the excitation module 11 is configured to:

Obtain electrochemical excitation parameters, which include reference excitation magnification, excitation duration and resting time;

Perform electrochemical excitation on the target cell based on the reference excitation ratio, and keep the excitation duration;

At the end of the electrochemical excitation, record the target cell resting start voltage corresponding to the target cell, and after the resting time, the target cell resting end voltage corresponding to the target cell is based on the target cell resting start voltage. The voltage and the target cell rest end voltage determine the rest voltage difference after electrochemical excitation.

The optional electrochemical excitation is charge excitation or discharge excitation; the reference excitation rate is 0.5C ~ 1.5C, the excitation duration is 10s ~ 30s, and the standing time is 60s ~ 240s.

Optionally, the monitoring module 12 is configured to:

Obtain the reference cell, perform a first-order linear fitting process on the Rc growth rate of the reference cell and the expansion rate of the reference cell, and obtain a prediction model of the impedance expansion rate;

Determine the target cell expansion rate based on the Rc growth rate and impedance expansion rate prediction model of the target cell; obtain the first detection result based on the target cell expansion rate, and obtain the second detection result based on the static voltage difference;

Based on the first detection result and the second detection result, the cell inflation condition of the target cell is determined.

Optionally, the monitoring module 12 is configured to:

Detecting whether the target cell expansion rate is greater than a first growth rate threshold to obtain a first detection result;

Detecting whether the static voltage difference is greater than a first static voltage difference threshold to obtain a second detection result;

If the first detection result is that the target cell expansion rate is greater than the first growth rate threshold and the second detection result is that the static voltage difference is greater than the first static voltage difference threshold, then determine the The target cell is in the state of cell inflation;

If the first detection result is that the target cell expansion rate is less than or equal to the first growth rate threshold and/or the second detection result is that the resting voltage difference is less than or equal to the first resting voltage difference threshold, it is determined that the target cell belongs to the normal state of the cell.

Optionally, the device 1 is also used for:

When the voltage of the reference cell is in the specified voltage interval, perform electrochemical excitation on the reference cell, measure the reference cell expansion value of the reference cell and obtain the reference characteristic impedance Rc value of the reference cell, wherein the specified voltage interval is a cut-off voltage multiplier interval taking the cut-off voltage of the target cell as a reference, and the cut-off voltage multiplier interval is 0.8 to 0.95;

Determine the reference Rc growth rate based on the reference characteristic impedance Rc value, and determine the reference cell expansion rate based on the reference cell expansion value;

A first-order linear fitting process is performed based on the reference cell expansion rate and the reference Rc growth rate to obtain a prediction model of impedance expansion rate.

Optionally, the device 1 is also used to: obtain the cell capacity parameters corresponding to multiple reference cells and the open circuit voltage deviation at the same SOC, and obtain the cell capacity parameters and the open circuit voltage deviation from the Select a reference cell from multiple cells;

The reference battery is configured with a specified temperature range environment, and the reference battery is subjected to cyclic charging treatment with a reference charging rate and a reference number of cycles to obtain the reference battery after pretreatment of the battery.

Optionally, the cell capacity parameter is a cell design capacity value and an actual capacity fluctuation value, and the device 1 is also used for: selecting the cell design capacity value from the plurality of cells At least one candidate cell that is greater than the reference design capacity value and the actual capacity fluctuation value is less than the reference capacity fluctuation value;

Selecting a reference cell whose open-circuit voltage deviation is smaller than a deviation threshold from the candidate cells.

The implementation principle and technical effects of the cell monitoring provided by the embodiment of the present application are the same as those of the foregoing method embodiments. For brief description, for the parts not mentioned in the device embodiments, reference may be made to the corresponding content in the foregoing method embodiments.

It should be noted that, when the cell monitoring device provided in the above embodiment executes the cell monitoring method, the division of the above functional modules is used as an example for illustration. In practical applications, the above functions can be assigned to different functions Module completion means that the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the cell monitoring device provided in the above embodiments and the cell monitoring method embodiments belong to the same concept, and the implementation process thereof is detailed in the method embodiments, and will not be repeated here.

The serial numbers of the above embodiments of the present application are for description only, and do not represent the advantages and disadvantages of the embodiments.

The embodiment of the present application also provides a computer storage medium, and the computer storage medium can store a plurality of instructions, and the instructions are suitable for being loaded and executed by a processor as described in the above-mentioned embodiments shown in FIGS. 1 to 6 . For the target cell monitoring method, the specific execution process can refer to the specific description of the embodiments shown in FIG. 1 to FIG. 6 , and details are not repeated here.

The present application also provides a computer program product, the computer program product stores at least one instruction, and the at least one instruction is loaded by the processor and executes the target computer as shown in the above-mentioned embodiments shown in Fig. 1 to Fig. 6 . For the core monitoring method, the specific execution process can refer to the specific description of the embodiments shown in FIG. 1 to FIG. 6 , and details are not repeated here.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented through computer programs to instruct related hardware, and the programs can be stored in a computer-readable storage medium. During execution, it may include the processes of the embodiments of the above-mentioned methods. Wherein, the storage medium may be a magnetic disk, an optical disk, a read-only memory or a random access memory, and the like.

The above disclosures are only preferred embodiments of the present application, which certainly cannot limit the scope of the present application. Therefore, equivalent changes made according to the claims of the present application still fall within the scope of the present application.

Claims (10)

1. A cell monitoring method, characterized in that the method comprises: When the voltage of the target cell is within a specified voltage interval, perform electrochemical excitation on the target cell, determine the static voltage difference after the electrochemical excitation, and obtain the characteristic impedance Rc value of the target cell, wherein , the specified voltage interval is a cut-off voltage multiplier interval taking the cut-off voltage of the target cell as a reference, and the cut-off voltage multiplier interval is 0.8 to 0.95; determining the Rc growth rate based on the characteristic impedance Rc value; Monitoring the inflation of the target battery based on the Rc growth rate of the target battery and the static voltage difference. 2. The method according to claim 1, wherein said performing electrochemical excitation on said target cell, and determining the resting voltage difference after said electrochemical excitation comprises: Acquiring electrochemical excitation parameters, the electrochemical excitation parameters include reference excitation magnification, excitation duration and rest period; performing electrochemical excitation on the target cell based on the reference excitation ratio, and maintaining the excitation duration; When the electrochemical excitation is ended, record the target cell static initial voltage corresponding to the target cell, and after the static period, the target cell corresponding to the target cell static end voltage is based on the The static voltage difference after the electrochemical excitation is determined by the target cell static initial voltage and the target cell static end voltage; The electrochemical excitation is charge excitation or discharge excitation, the reference excitation rate is 0.5C-1.5C, the excitation duration is 10s-30s, and the standing time is 60s-240s. 3. The method according to claim 1, wherein the monitoring the flatulence of the target cell based on the Rc growth rate and the static voltage difference comprises: Obtain the reference cell, perform a first-order linear fitting process on the Rc growth rate of the reference cell and the expansion rate of the reference cell, and obtain a prediction model of the impedance expansion rate; Determine the target cell expansion rate based on the Rc growth rate of the target cell and the impedance expansion rate prediction model; obtain a first detection result based on the target cell expansion rate, and obtain a second detection result based on the static voltage difference result; Based on the first detection result and the second detection result, determine the battery inflation condition of the target battery cell. 4. The method according to claim 3, wherein the first detection result is obtained based on the target cell expansion rate, the second detection result is obtained based on the static voltage difference, and the second detection result is obtained based on the first detection As a result and the second detection result, determining the cell inflation of the target cell includes: Detecting whether the target cell expansion rate is greater than a first growth rate threshold to obtain a first detection result; Detecting whether the static voltage difference is greater than a first static voltage difference threshold to obtain a second detection result; If the first detection result is that the target cell expansion rate is greater than the first growth rate threshold and the second detection result is that the static voltage difference is greater than the first static voltage difference threshold, then determine the The target cell is in the state of cell inflation; If the first detection result is that the target cell expansion rate is less than or equal to the first growth rate threshold and/or the second detection result is that the resting voltage difference is less than or equal to the first resting voltage difference threshold, it is determined that the target cell belongs to the normal state of the cell. 5. The method according to claim 3, characterized in that, the acquisition of the reference cell involves performing a first-order linear fitting process on the Rc growth rate of the reference cell and the expansion rate of the reference cell to obtain a prediction of the impedance expansion rate The model also includes: When the voltage of the reference cell is in the specified voltage range, perform electrochemical excitation on the reference cell, measure the reference cell expansion value of the reference cell and obtain the reference characteristic impedance Rc value of the reference cell; Determine the reference Rc growth rate based on the reference characteristic impedance Rc value, and determine the reference cell expansion rate based on the reference cell expansion value; A first-order linear fitting process is performed based on the reference cell expansion rate and the reference Rc growth rate to obtain a prediction model of impedance expansion rate. 6. method according to claim 3, is characterized in that, described method also comprises following pretreatment step: Obtaining cell capacity parameters corresponding to multiple cells and open circuit voltage deviations at the same SOC, and selecting a reference cell from the plurality of cells based on the cell capacity parameters and the open circuit voltage deviation; The reference battery is configured with a specified temperature range environment, and the reference battery is subjected to cyclic charging treatment with a reference charging rate and a reference number of cycles to obtain the reference battery after pretreatment of the battery. 7. The method according to claim 6, wherein the cell capacity parameter is a cell design capacity value and an actual capacity fluctuation value, The selecting a reference cell from the plurality of cells based on the cell capacity parameter and the open-circuit voltage deviation includes: Selecting at least one candidate battery cell whose design capacity value of the battery cell is greater than the reference design capacity value and whose actual capacity fluctuation value is smaller than the reference capacity fluctuation value; Selecting a reference cell whose open-circuit voltage deviation is smaller than a deviation threshold from the candidate cells. 8. A cell monitoring device, characterized in that the device comprises: An excitation module, configured to perform electrochemical excitation on the target cell when the voltage of the target cell is within a specified voltage range, determine the resting voltage difference after the electrochemical excitation, and obtain the characteristics of the target cell Impedance Rc value; A monitoring module, configured to determine the Rc growth rate based on the characteristic impedance Rc value; The monitoring module is configured to monitor the inflation of the target battery based on the Rc growth rate of the target battery and the static voltage difference. 9. A battery management system, characterized in that it is connected to a battery, and the battery contains at least one battery cell, and the battery management system is used to perform the monitoring of cell flatulence according to any one of claims 1-7 method. 10. An electronic device, characterized by comprising: a body, a battery management system, and a battery connected to the battery management system, and the battery includes at least one battery cell; The battery is used to power the body; The battery management system is used to execute the cell inflation monitoring method according to any one of claims 1-7.