Battery health condition judgment method and device, equipment and storage medium

Abstract

The invention discloses a method for judging the health condition of a battery, and the method comprises the steps: obtaining a function of voltage and time at two ends of the battery, enabling the function of voltage and time at two ends of the battery to correspond to an equivalent circuit model of the battery, and enabling parameters of the function to correspond to physical quantities in the equivalent circuit model, and substituting the voltage and time data at the two ends of the battery, the ohmic internal resistance and the electrochemical transfer internal resistance into the function relationship between the voltage and the time at the two ends of the battery, fitting the function relationship between the voltage and the time at the two ends of the battery corresponding to the equivalent circuit model, determining parameters of the function, and judging the health condition of the battery according to the parameters. The number of unknown variables in the equivalent circuit model is reduced, and the overfitting problem is avoided. The invention further discloses a device, equipment and a storage medium.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery health monitoring, in particular to a battery health determination method, device, equipment and storage medium. BACKGROUND

[0002] With the popularity of electric vehicles and portable electronic devices, lithium-ion batteries are widely used as the main energy storage device. Accurate assessment of battery health (State of Health, SOH) is of great significance to ensure safe operation of the battery, prolong its service life and improve system reliability. Currently, the assessment methods of battery health mainly include the assessment method based on battery capacity and the assessment method based on battery internal resistance. Among them, the assessment method based on battery internal resistance is widely concerned in practical application due to its strong real-time performance, no need for full charge and discharge and other advantages.

[0003] The battery equivalent circuit model is an important tool for studying the internal characteristics of the battery. The prior art can accurately characterize the electrochemical characteristics of the battery by establishing a reasonable equivalent circuit model.

[0004] Patent document CN108594132A discloses a battery equivalent circuit model, which includes a voltage source for characterizing the open-circuit voltage of the battery, an electrochemical polarization simulation circuit, a concentration polarization simulation circuit and an ohmic resistance simulation circuit, but cannot accurately reflect the health status of the positive and negative electrodes of the battery.

[0005] Patent document CN111948560A discloses a lithium battery health state estimation method based on a multi-factor evaluation model, which establishes a first-order RC equivalent circuit model of the lithium-ion battery, and estimates the ohmic resistance, polarization resistance and polarization capacitance of the battery online through a Kalman filtering algorithm, but cannot accurately reflect the health status of the battery.

[0006] Patent document CN114997091A discloses an automatic fitting method and device for parameters of a second-order RC equivalent circuit model, which determines each parameter by fitting a second-order equivalent circuit model, but there are many parameters and the problem of overfitting exists.

[0007] However, the prior art still has the following problems: first, when detecting the internal parameters of the battery by the direct current method, only the direct current resistance can be obtained, and the various internal resistance components of the battery cannot be further divided, resulting in low monitoring accuracy and difficulty in accurately reflecting the health status of the battery. Second, although the impedance spectrum method can provide more detailed internal parameter information of the battery, the detection device is complex and difficult to miniaturize, and the fitting method is complex, increasing the difficulty of practical application. When fitting and detecting the internal parameters of the battery by the equivalent circuit model method, the problem of curve overfitting often occurs, affecting the accuracy of parameter identification. Therefore, how to establish a method for accurately identifying the internal parameters of the battery and effectively evaluating the health status of the battery has become a technical problem to be solved. SUMMARY

[0008] The purpose of the present application is to solve the problem of how to establish a method for accurately identifying the internal parameters of the battery and effectively evaluating the health status of the battery.

[0009] In a first aspect, the present application provides a method for judging the health status of a battery, comprising:

[0010] obtaining a function of the voltage across the battery and time, the function of the voltage across the battery and time corresponding to an equivalent circuit model of the battery, the parameters of the function corresponding to physical quantities in the equivalent circuit model, the equivalent circuit model comprising:

[0011] a first resistor for representing the ohmic resistance of the battery;

[0012] a first circuit unit electrically connected to the first resistor and comprising a second resistor, the first circuit unit for representing the polarization process caused by the negative electrode electrochemical reaction of the battery;

[0013] a second circuit unit electrically connected to the first circuit unit and comprising a third resistor, the second circuit unit for representing the polarization process caused by the positive electrode electrochemical reaction of the battery, the sum of the second resistor and the third resistor being the electrochemical transfer resistance;

[0014] obtaining the ohmic resistance and the electrochemical transfer resistance of the battery, determining the first resistor according to the ohmic resistance, and determining the sum of the second resistor and the third resistor according to the electrochemical transfer resistance;

[0015] applying a direct current to the battery by a voltage source, obtaining data of the voltage across the battery and time, substituting the data of the voltage across the battery and time, the ohmic resistance and the electrochemical transfer resistance into the function relationship of the voltage across the battery and time, fitting the function relationship of the voltage across the battery and time corresponding to the equivalent circuit model, determining the parameters of the function, the parameters including the first resistor, the second resistor and the third resistor;

[0016] Determine the health condition of the battery according to the parameters.

[0017] By adopting the technical scheme, the ohmic internal resistance and the electrochemical transfer internal resistance, which are two core parameters with deterministic physical meanings, of the battery are accurately obtained before fitting the equivalent circuit model. Based on the corresponding relationship between the components in the equivalent circuit model and the physical characteristics inside the battery, a fixed constraint relationship is further established: one, the ohmic internal resistance is equal to the first resistance in the model; two, the sum of the second resistance and the third resistance in the model is equal to the electrochemical transfer internal resistance. The fixed constraint relationship established by the above method directly reduces the number of unknown variables in the voltage and time function corresponding to the equivalent circuit model by mapping the known parameters and the parameters of the model, and further reduces the degrees of freedom of the fitting process, thereby avoiding the problem that the mathematical fitting result deviates from the actual physical characteristics of the battery due to too many variables, that is, avoiding the overfitting problem. Therefore, the parameters obtained by fitting can truly and accurately reflect the dynamic process and polarization evolution law of the electrochemical reaction inside the battery, significantly improve the accuracy of parameter identification of the equivalent circuit model, provide reliable parameter support for quantitative determination of the health condition of the battery, and finally effectively improve the accuracy of the determination of the health condition of the battery.

[0018] According to another specific embodiment of the present application, determining the health condition of the battery according to the parameters comprises:

[0019] Applying the same direct constant current to the battery n times by the voltage source to obtain a plurality of groups of parameters, each group of parameters comprising n fitting values of the same parameter, n being a positive integer greater than or equal to 2;

[0020] Calculating the variation degree of each group of parameters;

[0021] Determining the health condition of the battery according to the variation degree of each group of parameters.

[0022] According to another specific embodiment of the present application, the variation degree is a relative average change rate, and the relative average change rate is the change rate of the nth parameter relative to the average value of the group of parameters.

[0023] According to another specific embodiment of the present application, determining the health condition of the battery according to the variation degree of each group of parameters comprises:

[0024] Determining the root of the sum of squares of the relative average change rates of the plurality of groups of parameters;

[0025] Determining the health condition of the battery according to the root of the sum of squares.

[0026] According to another specific embodiment of the present application, the first circuit unit further comprises a first capacitor in parallel with the second resistance; the second circuit unit further comprises a second capacitor in parallel with the third resistance; and the parameters further comprise the first capacitor and the second capacitor.

[0027] According to another specific embodiment of the present application, the function relationship between the voltage across the battery and the time is:

[0028] (Formula 1)

[0029] wherein, represents the open circuit voltage of the battery, represents the current value of the direct current constant current, represents the first resistor, represents the second resistor, represents the first capacitor, represents the third resistor, represents the second capacitor.

[0030] According to another specific embodiment of the present application, obtaining the ohmic resistance and the electrochemical transfer resistance of the battery comprises:

[0031] applying an alternating current of a fixed frequency to the battery, and testing the voltage across the battery when the alternating current of the fixed frequency is applied to the battery;

[0032] obtaining the amplitude of the current, the phase shift of the current, the amplitude of the voltage, and the phase shift of the voltage;

[0033] determining the ohmic resistance according to the amplitude of the current, the phase shift of the current, the amplitude of the voltage, and the phase shift of the voltage.

[0034] According to another specific embodiment of the present application, determining the ohmic resistance and the electrochemical transfer resistance of the battery comprises:

[0035] stopping after constant current charging or constant current discharging of the battery;

[0036] testing the voltage across the battery at the first time and the second time respectively, corresponding to the first voltage and the second voltage respectively, the first time being the time when the constant current charging or the constant current discharging is stopped, and the second time being the time of 8-12 ms after the constant current charging or the constant current discharging is stopped;

[0037] determining the sum of the ohmic resistance and the electrochemical transfer resistance according to the difference between the second voltage and the first voltage.

[0038] In a second aspect, the present application further discloses a battery health condition determination device, comprising:

[0039] The function acquisition module is used to acquire functions representing the voltage and time at the battery terminals. These functions correspond to the battery's equivalent circuit model, and the parameters of the functions correspond to physical quantities in the equivalent circuit model. The equivalent circuit model includes: a first resistor, used to characterize the battery's ohmic internal resistance; a first circuit unit, electrically connected to the first resistor and including a second resistor, used to characterize the polarization process caused by the negative electrode electrochemical reaction of the battery; and a second circuit unit, electrically connected to the first circuit unit and including a third resistor, used to characterize the polarization process caused by the positive electrode electrochemical reaction of the battery. The sum of the second and third resistors is the electrochemical transfer internal resistance.

[0040] The internal resistance determination module is used to obtain the ohmic internal resistance and electrochemical transfer internal resistance of the battery, determine the first resistance based on the ohmic internal resistance, and determine the sum of the second and third resistances based on the electrochemical transfer internal resistance.

[0041] The DC test module is used to apply a constant DC current to the battery through a voltage source to obtain data on the voltage and time across the battery terminals. Based on the relationship between the ohmic internal resistance and the first resistance, and the relationship between the electrochemical transfer internal resistance and the second and third resistances, the module substitutes the data on the voltage and time across the battery terminals, the ohmic internal resistance and the electrochemical transfer internal resistance into the functional relationship of the voltage and time across the battery terminals. It then fits the functional relationship of the voltage and time across the battery terminals corresponding to the equivalent circuit model to determine the parameters of the function, including the first resistance, the second resistance and the third resistance.

[0042] The battery health status assessment module is used to determine the battery's health status based on parameters.

[0043] Using the above technical solution, before fitting the equivalent circuit model, the two core parameters with deterministic physical significance—ohmic internal resistance and electrochemical transfer internal resistance—have been accurately obtained. Based on the correspondence between the components in the equivalent circuit model and the internal physical characteristics of the battery, fixed constraints are further established: first, the ohmic internal resistance is equal to the first resistance in the model; second, the sum of the second and third resistances in the model equals the electrochemical transfer internal resistance. These fixed constraints, by clearly defining the mapping relationship between known parameters and model parameters, directly reduce the number of unknown variables in the voltage and time functions corresponding to the equivalent circuit model, thereby reducing the degrees of freedom in the fitting process. This fundamentally avoids the problem of mathematical fitting results deviating from the actual physical characteristics of the battery due to too many dependent variables, thus preventing overfitting. Therefore, the fitted parameters can truly and accurately reflect the dynamic process and polarization evolution law of the internal electrochemical reaction of the battery, significantly improving the accuracy of parameter identification in the equivalent circuit model, providing reliable parameter support for the quantitative determination of battery health status, and ultimately effectively improving the accuracy of battery health status assessment.

[0044] Thirdly, the present invention also discloses an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-mentioned method for judging the health status of the battery.

[0045] Using the above technical solution, before fitting the equivalent circuit model, the two core parameters with deterministic physical significance—ohmic internal resistance and electrochemical transfer internal resistance—have been accurately obtained. Based on the correspondence between the components in the equivalent circuit model and the internal physical characteristics of the battery, fixed constraints are further established: first, the ohmic internal resistance is equal to the first resistance in the model; second, the sum of the second and third resistances in the model equals the electrochemical transfer internal resistance. These fixed constraints, by clearly defining the mapping relationship between known parameters and model parameters, directly reduce the number of unknown variables in the voltage and time functions corresponding to the equivalent circuit model, thereby reducing the degrees of freedom in the fitting process. This fundamentally avoids the problem of mathematical fitting results deviating from the actual physical characteristics of the battery due to too many dependent variables, thus preventing overfitting. Therefore, the fitted parameters can truly and accurately reflect the dynamic process and polarization evolution law of the internal electrochemical reaction of the battery, significantly improving the accuracy of parameter identification in the equivalent circuit model, providing reliable parameter support for the quantitative determination of battery health status, and ultimately effectively improving the accuracy of battery health status assessment.

[0046] Fourthly, the present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described method for determining the health status of a battery.

[0047] Using the above technical solution, before fitting the equivalent circuit model, the two core parameters with deterministic physical significance—ohmic internal resistance and electrochemical transfer internal resistance—have been accurately obtained. Based on the correspondence between the components in the equivalent circuit model and the internal physical characteristics of the battery, fixed constraints are further established: first, the ohmic internal resistance is equal to the first resistance in the model; second, the sum of the second and third resistances in the model equals the electrochemical transfer internal resistance. These fixed constraints, by clearly defining the mapping relationship between known parameters and model parameters, directly reduce the number of unknown variables in the voltage and time functions corresponding to the equivalent circuit model, thereby reducing the degrees of freedom in the fitting process. This fundamentally avoids the problem of mathematical fitting results deviating from the actual physical characteristics of the battery due to too many dependent variables, thus preventing overfitting. Therefore, the fitted parameters can truly and accurately reflect the dynamic process and polarization evolution law of the internal electrochemical reaction of the battery, significantly improving the accuracy of parameter identification in the equivalent circuit model, providing reliable parameter support for the quantitative determination of battery health status, and ultimately effectively improving the accuracy of battery health status assessment. Attached Figure Description

[0048] Figure 1 This is an equivalent circuit diagram of an embodiment of the present invention;

[0049] Figure 2 The flowchart of the battery health status judgment method according to an embodiment of the present invention Figure 1 ;

[0050] Figure 3 The flowchart of the battery health status judgment method according to an embodiment of the present invention Figure 2 ;

[0051] Figure 4 The flowchart of the battery health status judgment method according to an embodiment of the present invention Figure 3 ;

[0052] Figure 5 The flowchart of the battery health status judgment method according to an embodiment of the present invention Figure 4 ;

[0053] Figure 6 The flowchart of the battery health status judgment method according to an embodiment of the present invention Figure 5 ;

[0054] Figure 7 This is a schematic diagram of the battery health status determination device according to an embodiment of the present invention. Figure 1 ;

[0055] Figure 8 This is a schematic diagram of the battery health status determination device according to an embodiment of the present invention. Figure 2 ;

[0056] Figure 9 This is a schematic diagram of the battery health status determination device according to an embodiment of the present invention. Figure 3 ;

[0057] Figure 10 This is a schematic diagram of the battery health status determination device according to an embodiment of the present invention. Figure 4 ;

[0058] Figure 11 This is a schematic diagram of the battery health status determination device according to an embodiment of the present invention. Figure 5 ;

[0059] Figure 12 This is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention;

[0060] Figure 13 This is a schematic diagram of the first resistance change according to an embodiment of the present invention;

[0061] Figure 14 This is a schematic diagram of the second resistance change according to an embodiment of the present invention;

[0062] Figure 15 This is a schematic diagram of the third resistance change in an embodiment of the present invention;

[0063] Figure 16 This is a schematic diagram illustrating the change of the decision number in an embodiment of the present invention. Detailed Implementation

[0064] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention is presented in conjunction with preferred embodiments, this does not mean that the features of the invention are limited to these embodiments. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a deep understanding of the invention, many specific details will be included in the following description. The invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the invention, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0065] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0066] The terms “first”, “second”, etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0067] In the description of this embodiment, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment based on the specific circumstances.

[0068] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0069] Firstly, reference Figure 1 and Figure 2 This invention provides a method for judging the health status of a battery, comprising:

[0070] S1: A function that obtains the voltage and time across the battery terminals. The function of the voltage V(t) and time t across the battery terminals corresponds to the equivalent circuit model of the battery, and the parameters of the function correspond to the physical quantities in the equivalent circuit model.

[0071] Equivalent circuit model such as Figure 1 As shown, the equivalent circuit model includes:

[0072] First resistor Used to characterize the ohmic internal resistance of a battery Ohmic internal resistance The inherent internal resistance of components including battery electrodes, electrolyte, and current collector is the basic internal resistance component when the battery is unpolarized.

[0073] The first circuit unit, and the first resistor Electrical connection, and includes a second resistor. The first circuit unit is used to characterize the polarization process caused by the electrochemical reaction at the negative electrode of the battery. The first circuit unit and the first resistor... Series connection. The first circuit unit includes a second resistor. The first circuit unit reflects the polarization effect generated at the negative electrode during the electrochemical reaction process, and is used to quantify the intensity of the negative electrode polarization process.

[0074] The second circuit unit is electrically connected to the first circuit unit and includes a third resistor. The second circuit unit is used to characterize the polarization process caused by the positive electrode electrochemical reaction of the battery. The second circuit unit includes a third resistor. The second circuit unit reflects the polarization effect generated at the battery's positive electrode during the electrochemical reaction process, and is used to quantify the intensity of the positive electrode polarization process. Among them, the second resistor... With the third resistor The sum of these two factors constitutes the electrochemical transfer resistance. The electrochemical transfer resistance is the sum of the polarization resistance caused by the positive electrode electrochemical reaction and the polarization resistance caused by the negative electrode electrochemical reaction.

[0075] Battery voltage The functional relationship between time t and the time t is:

[0076] (Formula 1)

[0077] in, This indicates the open-circuit voltage of the battery. This represents the value of the DC constant current. Indicates the first resistance. Indicates the second resistor. Indicates the first capacitor. Indicates the third resistor. This indicates the second capacitor.

[0078] S2: Obtain the ohmic internal resistance of the battery. and electrochemical transfer resistance According to Ohm's internal resistance Determine the first resistor The second resistance is determined based on the electrochemical transfer internal resistance. and the third resistor sum.

[0079] Among them, obtaining the ohmic internal resistance The values ​​can be obtained through a single-frequency alternating current test. Specifically, after the battery has been left to stand, a single-frequency alternating current test is performed, and the alternating voltage and current are fitted using formulas 2 and 3.

[0080] (Formula 2)

[0081] Where V represents the voltage of a single-frequency alternating current test. This represents the DC offset of the voltage. f represents the voltage amplitude, and f represents the voltage frequency. This represents the phase shift of the voltage, and x represents time.

[0082] (Formula 3)

[0083] Where I represents the current in a single-frequency alternating current test. Indicates the DC offset of the current. f represents the amplitude of the current, and f represents the frequency of the current. This represents the phase shift of the current, and x represents time.

[0084] The ohmic resistance can be obtained using Formula 4. :

[0085] (Formula 4)

[0086] Then, based on the amplitude of the current Phase shift of the current The amplitude of the voltage Phase shift of voltage Determine the ohmic internal resistance .

[0087] The electrochemical transfer resistance can be determined by summing the ohmic polarization and the electrochemical transfer polarization. Specifically, the battery is charged with current I1 and then charging is stopped. The battery voltage V1 at the first moment and V2 at the second moment are measured. The first moment represents the end of charging, and the second moment represents 8-12 ms after charging ends. The sum of the ohmic polarization and the electrochemical transfer polarization is then determined according to Formula 5. .

[0088] (Formula 5)

[0089] in, This represents the sum of ohmic polarization and electrochemical transferred polarization. Indicates Ohmic polarization, V1 represents electrochemical transfer polarization, V2 represents the voltage at the second moment, and V1 represents the voltage at the first moment.

[0090] Based on the sum of Ohmic polarization and electrochemical transfer polarization Current I1 and internal resistance in ohms The electrochemical transfer resistance is obtained according to Formula 6. .

[0091] (Formula 6)

[0092] in, Indicates the electrochemical transfer resistance. I1 represents the sum of ohmic polarization and electrochemical transfer polarization, and represents the current. This represents the internal resistance of the Ohm.

[0093] According to Ohm's internal resistance Determine the first resistor Specifically, the ohmic internal resistance The first internal resistance is R1. The second resistance is determined based on the electrochemical transfer internal resistance. and the third resistor The sum. Specifically, the electrochemical transfer internal resistance. For the second resistor With the third resistor sum.

[0094] S3: Apply a constant DC current to the battery using a voltage source to obtain data on the voltage and time across the battery terminals, based on the ohmic internal resistance. and the first resistor Relationship, electrochemical transfer resistance With the second resistor and the third resistor The relationship between the voltage and time data at both ends of the battery, and the ohmic internal resistance... and electrochemical transfer resistance Substituting the functional relationship between the voltage and time across the battery terminals, we fit the functional relationship between the voltage and time across the battery terminals to the equivalent circuit model. That is, we combine the voltage and time data across the battery terminals with the ohmic internal resistance data. and electrochemical transfer resistance Substitute into Formula 1:

[0095] (Formula 1)

[0096] in, This indicates the open-circuit voltage of the battery. This represents the value of the DC constant current. Indicates the first resistance. Indicates the second resistor. Indicates the first capacitor. Indicates the third resistor. This indicates the second capacitor.

[0097] Determine the parameters of the function, including the first resistance. Second resistor and the third resistor In Formula 1, the open-circuit voltage Given that the value of the DC constant current I is known, substitute it into the first resistor. equal to ohmic internal resistance It is later known that the second resistor Unknown, first capacitor Unknown, third resistor for Second capacitor Unknown. The number of unknowns in Formula 1 has been reduced from 5 to 3. That is, the unknowns have changed from the first resistance. Second resistor First capacitor Third resistor Second capacitor These five unknowns become the second resistance. First capacitor Second capacitor These three unknowns. By reducing the number of unknowns, and keeping the amount of voltage and time data at both ends of the battery constant, overfitting is effectively reduced, and the accuracy of the fitting results is improved.

[0098] S4: Determine the battery's health status based on parameters. Specifically, based on the first resistance parameter... Second resistor and the third resistor Determine the battery's health status. Alternatively, check the first resistance parameter. Second resistor and the third resistor And the first capacitor parameter Second capacitor To determine the health status of the battery.

[0099] Using the above technical solution, the ohmic internal resistance of the battery has been accurately obtained before fitting the equivalent circuit model. and electrochemical transfer resistance These two core parameters possess deterministic physical significance. Based on the correspondence between the components in the equivalent circuit model and the internal physical characteristics of the battery, fixed constraints are further established: firstly, the ohmic internal resistance. With the first resistor in the model Equal; secondly, the second resistor in the model With the third resistor The sum equals the electrochemical transfer internal resistance The fixed constraint relationship established by the above method directly reduces the number of unknown variables in the voltage and time functions corresponding to the equivalent circuit model by clearly defining the mapping relationship between known parameters and model parameters. This reduces the degrees of freedom in the fitting process and fundamentally avoids the problem of deviation between the mathematical fitting results and the actual physical characteristics of the battery caused by too many dependent variables, thus avoiding overfitting. Therefore, the fitted parameters can truly and accurately reflect the dynamic process and polarization evolution law of the internal electrochemical reaction of the battery, significantly improving the accuracy of equivalent circuit model parameter identification, providing reliable parameter support for the quantitative determination of battery health status, and ultimately effectively improving the accuracy of battery health status assessment.

[0100] According to another specific embodiment of the present invention, reference is made to... Figure 3 S4: Determining the battery's health status based on parameters includes:

[0101] S41: Apply the same constant DC current to the battery n times using a voltage source to obtain multiple sets of parameters. Each set of parameters includes n fitted values ​​of the same parameter, where n is a positive integer greater than or equal to 2. For example, charge the battery to a preset state of charge, apply a constant DC current to the battery using a voltage source for the first time, and obtain the first resistance parameter. Second resistor and the third resistor The first fitted value: the first resistance The first fitted value Second resistor The first fitted value and the third resistor The first fitted value Then, discharge the battery to a preset state of charge, apply a second constant DC current to the battery, and obtain the first resistance parameter. Second resistor and the third resistor The second fitted value: the first resistance The second fitted value Second resistor The second fitted value and the third resistor The second fitted value Then discharge the battery to a preset state of charge, apply a constant DC current to the battery for the nth time, and obtain the first resistance parameter. Second resistor and the third resistor The nth fitted value: the first resistance The nth fitted value Second resistor The nth fitted value and the third resistor The nth fitted value For example, the first resistor The first fitted value First resistor The second fitted value and the first resistor The nth fitted value For a set of parameters, there are n fitted values.

[0102] S42: Calculate the degree of change in each group of parameters. That is, calculate the first resistance of each group. The degree of change, the second resistor in each group The degree of change and the third resistor in each group The degree of change.

[0103] S43: Determine the battery's health status based on the degree of change in each group of parameters. First resistor of each group. The degree of change, the second resistor in each group The degree of change and the third resistor in each group The degree of change. For example, judging the first resistance of each group. The degree of change, the second resistor in each group The degree of change and the third resistor in each group If the sum of the changes in the battery level exceeds a preset threshold, the battery is unhealthy; otherwise, the battery is healthy.

[0104] In the above embodiments, by applying the same DC constant current to the battery n times, the fitted values ​​of multiple sets of model core parameters (R1, R2, R3) are obtained. This avoids the influence of random errors and instantaneous operating condition fluctuations in a single test, making the parameter data more reflective of the battery's long-term stable internal characteristics and providing solid data support for health status assessment. By calculating the degree of change of each set of parameters, the battery health status is directly correlated with the dynamic evolution of the parameters, breaking through the limitations of traditional single threshold judgment. Combined with the first resistor... Second resistor and the third resistor Comprehensive analysis of these changes can fully capture the multi-dimensional degradation characteristics of battery ohmic internal resistance decay, positive electrode polarization anomalies, and negative electrode polarization anomalies, ensuring that the judgment results truly reflect the overall health status of the battery and its core components, significantly improving the accuracy and scientific validity of the judgment results. Each group's first resistance... The degree of change, the second resistor in each group The degree of change and the third resistor in each group The degree of change directly corresponds to the degradation trend of core performance, including the efficiency of electrochemical reactions and polarization capability within the battery. By setting a threshold for the degree of change, potential battery degradation risks can be identified in advance. Compared to traditional methods that rely on explicit characteristics such as battery capacity decay and voltage surges, this method ultimately achieves accurate, stable, and timely assessment of battery health.

[0105] According to another specific embodiment of the present invention, the degree of change is the relative average rate of change, which is the rate of change of the nth parameter relative to the average value of the set of parameters.

[0106] For example, calculate the first resistance according to Formula 7 and Formula 8. The relative average rate of change.

[0107] (Formula 7)

[0108] (Formula 8)

[0109] in, Represents the first resistance in the nth power. The average of the fitted values, Indicates the first resistor The fitted value of the i-th iteration, Indicates the first resistor The fitted value for the nth iteration. Indicates the first resistor The relative average rate of change.

[0110] Calculate the second resistor according to formulas 9 and 10. The relative average rate of change.

[0111] (Formula 9)

[0112] (Formula 10)

[0113] in, Represents the second resistor of the nth power. The average of the fitted values, Indicates the second resistor The fitted value of the i-th iteration, Indicates the second resistor The fitted value for the nth iteration. Indicates the second resistor The relative average rate of change.

[0114] Calculate the third resistor using formulas 11 and 12. The relative average rate of change.

[0115] (Formula 11)

[0116] (Formula 12)

[0117] in, Represents the third resistance of the nth power The average of the fitted values, Indicates the third resistor The fitted value of the i-th iteration, Indicates the third resistor The fitted value for the nth iteration. Indicates the third resistor The relative average rate of change.

[0118] According to the first resistor relative average rate of change Second resistor relative average rate of change Third resistor relative average rate of change To determine the health status of the battery.

[0119] In the above embodiments, by defining the relative average rate of change as a quantitative indicator of the degree of parameter change, the average of the fitted values ​​from multiple tests (e.g., n times the first resistance) is first measured. The average of the fitted values This method eliminates random errors from single tests and establishes baseline stable values ​​for parameters. Then, by defining a relative average rate of change, and calculating the ratio of the difference between the fitted parameter in the nth test and the average value to the average value, parameter changes are transformed into an intuitive and comparable percentage indicator. This avoids the judgment bias caused by differences in the magnitude of the parameters themselves, which is present in traditional absolute difference judgments. It provides a unified standard for evaluating the degree of change of different parameters, offering a rigorous quantitative basis for health status assessment and thus improving the accuracy of battery health status assessment.

[0120] Furthermore, using the average rate of change from multiple tests as a benchmark effectively amplifies subtle trends in parameter variation. In the early stages of battery degradation, core internal parameters, such as the first resistance corresponding to the ohmic internal resistance, are particularly sensitive. The second resistance corresponding to the internal resistance generated by the polarization of the negative electrode electrochemical reaction. And the third resistance corresponding to the internal resistance generated by the polarization of the positive electrode electrochemical reaction. Such subtle fluctuations often occur only slightly, making it difficult to capture them with a single test or absolute difference calculation. However, this embodiment, through averaging multiple sets of data and calculating relative changes, can transform these subtle fluctuations into identifiable relative rate of change signals. For example, when the polarization of the battery's negative electrode intensifies, leading to a decrease in the second resistance... When a small growth of 5% occurs, through The calculation can clearly quantify this change, and compared with traditional methods, it can identify signs of internal battery degradation earlier, allowing more time for battery health risk warnings and effectively avoiding safety hazards caused by accumulated degradation.

[0121] According to another specific embodiment of the present invention, reference is made to... Figure 4 S43: Judging the battery's health status based on the degree of change in each set of parameters includes:

[0122] S431: Determine the root of the sum of squares of the relative average rates of change of multiple sets of parameters. Specifically, as shown in Formula 15, calculate the first resistance. relative average rate of change Second resistor relative average rate of change Third resistor relative average rate of change The root of the sum of squares .

[0123] (Formula 15)

[0124] in, The first resistor Second resistor and the third resistor The root of the sum of squares of the relative average rate of change is also called the decision number.

[0125] In the above embodiments, the square root calculation method is used. On the one hand, it amplifies the relative average rate of change of each parameter. If a parameter shows a significant anomaly, its square term will highlight the impact of the anomaly on the overall index, preventing the anomaly of a single parameter from being diluted by other normal parameters. On the other hand, by calculating the root of the sum of squares of the relative average rates of change of multiple parameters, the degree of change of multiple parameters can be synergistically quantified. The degradation of ohmic internal resistance and electrochemical transfer internal resistance of positive and negative electrodes can be integrated into an intuitive numerical index, thereby comprehensively determining the health status of the battery.

[0126] Continue to refer to Figure 4 S432: Based on the roots of the sum of squares Determine the health status of the battery. Also known as the decision number. The larger the value, the greater the degree of change in the parameters of the battery's equivalent circuit model. If the value exceeds the preset threshold, it indicates that the battery's ohmic internal resistance or electrochemical transfer internal resistance is too high, suggesting an abnormal battery health condition.

[0127] In some embodiments, the number of decisions The magnitude of the value is positively correlated with the overall change in the core resistance parameters inside the battery. The larger the value, the higher the relative change of at least one or more of the first resistor R1, the second resistor R2, and the third resistor R3, reflecting a more significant degradation phenomenon, including increased ohmic loss inside the battery, abnormal polarization of the positive electrode electrochemical reaction, or abnormal polarization of the negative electrode electrochemical reaction.

[0128] In the above embodiments, the root of the sum of squares of the relative average rate of change of the parameters of the battery's equivalent circuit model (i.e., the decision number) is calculated. This method integrates the degradation levels of resistors R1, R2, and R3 into a unified quantitative index. It avoids the problem of difficulty in decision-making when some parameters are normal while others are abnormal, which is common in traditional single-parameter assessments. For example, if the relative average rate of change of resistor R1 is small but the relative average rate of change of resistor R2 is significantly excessive, a single-parameter assessment might misjudge battery health based on the normality of R1. However, by using the square root logic, the abnormal contribution of resistor R2 can be naturally amplified, ensuring that key degradation signals are not missed. There is no need to subjectively set parameter weights; the assessment objectively reflects the degradation impact based entirely on the degree of change of the parameters themselves, making the judgment results more closely reflect the actual health condition of the battery and significantly improving the comprehensiveness and accuracy of the assessment.

[0129] Furthermore, the number of judgments Its composition is directly related to the key physical processes inside the battery. A reading exceeding the preset threshold essentially indicates either excessive ohmic resistance or excessive electrochemical transfer resistance. These two factors correspond to different causes of degradation: excessive ohmic resistance may stem from electrode material wear and electrolyte aging, while excessive electrochemical transfer resistance may result from a decrease in the electrochemical activity of the positive or negative electrode. The judgment result can be further combined with the specific values ​​of the relative average change rate of each parameter to quickly pinpoint the core deterioration location and type. For example, if N(n) exceeds the standard, if If the percentage is the highest, the degradation can be traced back to abnormal electrochemical reactions at the negative electrode. This provides a clear technical basis for subsequent battery maintenance, such as targeted electrode replacement and electrolyte replenishment, reducing maintenance costs and extending battery life.

[0130] According to another specific embodiment of the present invention, reference continues to be made. Figure 1 The first circuit unit also includes a first capacitor. First capacitor With the second resistor Parallel connection. The first capacitor... The negative electrode electrochemical transfer capacitor is used to characterize the dynamic characteristics of charge accumulation and release in the negative electrode electrochemical reaction. Its parameter changes directly reflect the degree of degradation of the negative electrode interface reaction activity.

[0131] The second circuit unit also includes a second capacitor. Second capacitor With the third resistor Parallel connection; parameters also include the first capacitor. Second capacitor Among them, the second capacitor The positive electrode electrochemical transfer capacitor is used to characterize the change in charge storage capacity during the positive electrode electrochemical reaction. Its parameter fluctuations can accurately reflect the performance degradation caused by the structural stability of the positive electrode material (such as the shedding of active material and the decrease in electrolyte wettability).

[0132] S4: Determining the battery's health status based on model parameters includes:

[0133] S41: Apply the same constant DC current to the battery n times using a voltage source to obtain multiple sets of parameters. Each set of parameters includes n fitted values ​​of the same parameter, where n is a positive integer greater than or equal to 2. For example, charge the battery to a preset state of charge, apply a constant DC current to the battery using a voltage source for the first time, and obtain the parameter "first resistance". Second resistor First capacitor Third resistor Second capacitor The first fitted value: the first resistance The first fitted value Second resistor The first fitted value First capacitor The first fitted value Third resistor The first fitted value Second capacitor The first fitted value Then, discharge the battery to a preset state of charge, apply a second constant DC current to the battery, and obtain the first resistance parameter. Second resistor First capacitor Third resistor Second capacitor The second fitted value: the first resistance The second fitted value Second resistor The second fitted value First capacitor The second fitted value Third resistor The second fitted value Second capacitor The second fitted value Then, discharge the battery to a preset state of charge, apply a constant DC current to the battery for the nth time, and obtain the first resistance parameter. Second resistor First capacitor Third resistor Second capacitor The nth fitted value: the first resistance The nth fitted value Second resistor The nth fitted value First capacitor The nth fitted value Third resistor The nth fitted value Second capacitor The nth fitted value For example, the first resistor The first fitted value First resistor The second fitted value and the first resistor The nth fitted value For a set of parameters, there are n fitted values.

[0134] S42: Calculate the degree of change in each group of parameters. That is, calculate the first resistance of each group. The degree of change, the second resistor in each group The degree of change, the first capacitor of each group The degree of change, the third resistor in each group The degree of change and the second capacitor of each group The degree of change.

[0135] S43: Determine the battery's health status based on the degree of change in each group of parameters. First resistor of each group. The degree of change, the second resistor in each group The degree of change, the first capacitor of each group The degree of change, the third resistor in each group The degree of change and the second capacitor of each group The degree of change is used to determine the battery's health status. For example, judging the first resistance of each group. The degree of change, the second resistor in each group The degree of change, the first capacitor of each group The degree of change, the third resistor in each group The degree of change and the second capacitor of each group If the sum of the values ​​exceeds a preset threshold for the degree of change, the battery is unhealthy; otherwise, the battery is healthy.

[0136] Calculate the first capacitance according to formulas 11 and 12. The relative average rate of change.

[0137] (Formula 13)

[0138] (Formula 14)

[0139] in, Represents the first capacitor in the nth power. The average of the fitted values, Indicates the first capacitor The fitted value of the i-th iteration, Indicates the first capacitor The fitted value for the nth iteration. Indicates the first capacitor The relative average rate of change.

[0140] Calculate the second capacitor according to formulas 9 and 10. The relative average rate of change.

[0141] (Formula 9)

[0142] (Formula 10)

[0143] in, Represents the second capacitor of the nth power. The average of the fitted values, Indicates the second capacitor The fitted value of the i-th iteration, Indicates the second capacitor The fitted value for the nth iteration. Indicates the second capacitor The relative average rate of change.

[0144] Calculate the root of the sum of squares of the relative evaluation change rates of each parameter according to Formula 16.

[0145] (Formula 16)

[0146] In the above embodiments, the equivalent circuit model parameters include five core parameters: a first resistor R1 representing the ohmic internal resistance, R2 representing the negative electrode electrochemical transfer internal resistance, R3 representing the positive electrode electrochemical transfer internal resistance, a first capacitor C1 representing the negative electrode electrochemical transfer capacitance, and a second capacitor C2 representing the positive electrode electrochemical transfer capacitance, thereby achieving a full-dimensional characterization of the battery's ohmic loss, positive and negative electrode electrochemical reaction polarization, and charge storage capacity.

[0147] According to another specific embodiment of the present invention, the voltage at both ends of the battery The functional relationship between time t and the time t is:

[0148] (Formula 1)

[0149] in, This indicates the open-circuit voltage of the battery. This represents the value of the DC constant current. Indicates the first resistance. Indicates the second resistor. Indicates the first capacitor. Indicates the third resistor. This indicates the second capacitor.

[0150] Using the above technical solution, the voltage across the battery terminals is fitted. The functional relationship between the voltage across the battery and time t achieves a precise mapping between the equivalent circuit model and the actual electrochemical reaction process of the battery. The functional relationship between time t and the battery is represented by piecewise terms that correspond to different physical mechanisms within the battery: The term characterizes the instantaneous voltage drop caused by the ohmic internal resistance. The term characterizes the dynamic voltage decay caused by the polarization of the negative electrode electrochemical reaction. This term characterizes the dynamic voltage changes induced by the polarization of the positive electrode electrochemical reaction. This represents the open-circuit voltage of the battery. Formula 1 reflects the physical model of the internal electrochemical reactions, charge transfer, and storage processes of the battery, ensuring that the voltage response calculation results are highly consistent with the actual operating state of the battery.

[0151] According to another specific embodiment of the present invention, reference is made to... Figure 5 S2: Obtain the ohmic internal resistance of the battery. and electrochemical transfer resistance include:

[0152] S21: Apply a fixed-frequency alternating current to the battery and test the voltage across the battery terminals when the fixed-frequency alternating current is applied. By fixing the test frequency, based on the characteristic frequency preset for the battery type, it ensures that the AC signal at this frequency mainly responds to the ohmic internal resistance characteristics of the battery, reduces interference from other parameters such as polarization capacitance, simplifies the test process and the difficulty of signal analysis, and avoids the dependence on complex equipment for broadband testing, thereby achieving miniaturization and low cost of the test equipment.

[0153] S22: Obtain the amplitude of the current. Phase shift of current Voltage amplitude Phase shift of voltage Among them, the amplitude of the current The magnitude of the applied alternating current signal is the fundamental amplitude basis for calculating the internal resistance. The phase shift of the current... This characterizes the phase difference between the alternating current signal and a preset reference signal, reflecting the time delay characteristics of the current signal. The phase of the preset reference signal is, for example, the initial phase of the signal generator. Voltage amplitude. The voltage intensity characterizes the battery's response to an alternating current signal; its ratio to the current amplitude is directly related to the battery's impedance. Voltage phase shift. The phase difference between the battery response voltage signal and the current signal reflects the influence of internal ohmic losses and polarization processes on the signal phase. The phase shift caused by ohmic internal resistance exhibits deterministic characteristics and is the key basis for extracting ohmic internal resistance in this scheme.

[0154] S23: Based on the amplitude of the current Phase shift of current Voltage amplitude Phase shift of voltage Determine the ohmic internal resistance .

[0155] Specifically, the ohmic internal resistance is obtained according to Formula 4. :

[0156] (Formula 4)

[0157] Among them, the amplitude ratio According to the alternating current form of Ohm's law, the amplitude ratio The value characterizes the apparent impedance amplitude of the battery at the test frequency, and includes comprehensive impedance information resulting from the combined effects of ohmic internal resistance, polarization internal resistance, and polarization capacitance. This represents the phase difference between the voltage signal and the current signal, i.e., the impedance angle θ. The phase difference cosine term... The resistive component coefficient of the impedance is used in this embodiment at a fixed frequency. At this fixed frequency, the contribution of capacitive components such as polarization capacitors to the phase difference can be pre-calibrated and is known or negligible. It mainly reflects the proportion of ohmic internal resistance in the overall impedance, through The pure ohmic internal resistance component can be separated from the apparent impedance magnitude.

[0158] In the above embodiments, existing DC methods can only obtain the comprehensive DC internal resistance, including ohmic internal resistance and polarization internal resistance, and cannot separate the specific components; while traditional broadband AC methods can obtain ohmic internal resistance, they require complex impedance spectrum fitting, which is prone to errors in ohmic internal resistance identification due to fitting errors. The above technical solutions accurately extract the battery's ohmic internal resistance by combining fixed-frequency AC current excitation with signal amplitude and phase analysis. This provides reliable basic parameters for equivalent circuit model fitting and health status assessment.

[0159] According to another specific embodiment of the present invention, reference is made to... Figure 6 S2: Determine the ohmic internal resistance of the battery. and electrochemical transfer resistance include:

[0160] S24: Stop constant current charging or discharging of the battery. Perform constant current charging or discharging on the battery in the monitoring state, and stop the charging / discharging operation once the battery reaches the preset state of charge. This allows a stable polarization state to form inside the battery. Under constant current excitation, the battery will simultaneously generate ohmic polarization and electrochemical transfer polarization. After stopping charging and discharging, the ohmic polarization and electrochemical transfer polarization will exhibit differentiated decay patterns over time, thus allowing the calculation of a stable and constant electrochemical transfer polarization.

[0161] S25: Measure the voltage across the battery at the first and second time points, corresponding to the first voltage V1 and the second voltage V2, respectively. The first time point is when constant current charging or discharging stops. The second time point is 8-12 ms after the constant current charging or discharging stops. Ohmic polarization decays extremely quickly, typically within milliseconds, while electrochemical transfer polarization decays more slowly, generally completing within 8-12 ms. The second time point ensures that both ohmic polarization and electrochemical transfer polarization have essentially completed their decay. The difference between the second voltage V2 and the first voltage V1 represents the ohmic polarization. and electrochemical transfer polarization sum .

[0162] S26: Determine the ohmic internal resistance based on the difference between the second voltage V2 and the first voltage V1. and electrochemical transfer resistance sum.

[0163] Specifically, the ohmic internal resistance is determined according to formulas 5, 6, and 17. and electrochemical transfer resistance sum .

[0164] (Formula 5)

[0165] in, This represents the sum of ohmic polarization and electrochemical transferred polarization. Indicates Ohmic polarization, V1 represents electrochemical transfer polarization, V2 represents the voltage at the second moment, and V1 represents the voltage at the first moment.

[0166] Based on the sum of Ohmic polarization and electrochemical transfer polarization Current I1 and internal resistance in ohms The electrochemical transfer resistance is obtained according to Formula 6. .

[0167] (Formula 6)

[0168] in, Indicates the electrochemical transfer resistance. I1 represents the sum of ohmic polarization and electrochemical transfer polarization, and represents the current. This represents the internal resistance of the Ohm.

[0169] (Formula 17)

[0170] in, Indicates ohmic internal resistance and electrochemical transfer resistance sum.

[0171] In the above embodiments, by accurately capturing the voltage transient changes at the first and second moments, the separation of ohmic polarization and electrochemical transfer polarization is achieved by utilizing the time difference of polarization decay, thereby obtaining the ohmic internal resistance. and electrochemical transfer resistance In the subsequent equivalent circuit model, the first resistor R1 is equal to the ohmic internal resistance. The sum of the second and third resistances equals the electrochemical transfer internal resistance. The constraint fitting provides clear parameter basis. It eliminates the need for broadband signal generators or spectrum analyzers relying on AC methods; testing can be completed with only a constant current source and a high-precision voltage acquisition module. The equipment has a simple structure, is easy to miniaturize, and is suitable for engineering scenarios such as online monitoring of vehicle batteries and on-site battery testing of portable devices, significantly improving the feasibility of the technical solution.

[0172] Secondly, refer to Figure 7 The present invention also discloses a battery health status judgment device 100, comprising:

[0173] The function acquisition module 110 is used to acquire functions for the voltage and time at the battery terminals. The functions for the voltage and time at the battery terminals correspond to the equivalent circuit model of the battery. The parameters of the functions correspond to the physical quantities in the equivalent circuit model. The equivalent circuit model includes: a first resistor, used to characterize the ohmic internal resistance of the battery; a first circuit unit, electrically connected to the first resistor and including a second resistor, the first circuit unit being used to characterize the polarization process caused by the negative electrode electrochemical reaction of the battery; a second circuit unit, electrically connected to the first circuit unit and including a third resistor, the second circuit unit being used to characterize the polarization process caused by the positive electrode electrochemical reaction of the battery, the sum of the second resistor and the third resistor being the electrochemical transfer internal resistance;

[0174] The internal resistance determination module 120 is used to obtain the ohmic internal resistance and electrochemical transfer internal resistance of the battery, determine the first resistance based on the ohmic internal resistance, and determine the sum of the second and third resistances based on the electrochemical transfer internal resistance.

[0175] The DC test module 130 is used to apply a constant DC current to the battery through a voltage source to obtain data on the voltage and time across the battery terminals. Based on the relationship between the ohmic internal resistance and the first resistance, and the relationship between the electrochemical transfer internal resistance and the second and third resistances, the module substitutes the data on the voltage and time across the battery terminals, the ohmic internal resistance and the electrochemical transfer internal resistance into the functional relationship of the voltage and time across the battery terminals. The module then fits the functional relationship of the voltage and time across the battery terminals corresponding to the equivalent circuit model to determine the parameters of the function, including the first resistance, the second resistance and the third resistance.

[0176] The battery health status assessment module 140 is used to determine the health status of the battery based on parameters.

[0177] Using the above technical solution, before fitting the equivalent circuit model, the two core parameters with deterministic physical significance—ohmic internal resistance and electrochemical transfer internal resistance—have been accurately obtained. Based on the correspondence between the components in the equivalent circuit model and the internal physical characteristics of the battery, fixed constraints are further established: first, the ohmic internal resistance is equal to the first resistance in the model; second, the sum of the second and third resistances in the model equals the electrochemical transfer internal resistance. These fixed constraints, by clearly defining the mapping relationship between known parameters and model parameters, directly reduce the number of unknown variables in the voltage and time functions corresponding to the equivalent circuit model, thereby reducing the degrees of freedom in the fitting process. This fundamentally avoids the problem of mathematical fitting results deviating from the actual physical characteristics of the battery due to too many dependent variables, thus preventing overfitting. Therefore, the fitted parameters can truly and accurately reflect the dynamic process and polarization evolution law of the internal electrochemical reaction of the battery, significantly improving the accuracy of parameter identification in the equivalent circuit model, providing reliable parameter support for the quantitative determination of battery health status, and ultimately effectively improving the accuracy of battery health status assessment.

[0178] According to another specific embodiment of the present invention, reference is made to... Figure 8 The battery health status assessment device 100 also includes:

[0179] The parameter fitting module 141 is used to apply the same DC constant current to the battery n times through a voltage source to obtain multiple sets of parameters. Each set of parameters includes n fitted values ​​of the same parameter, where n is a positive integer greater than or equal to 2.

[0180] The degree of change calculation module 142 is used to calculate the degree of change of each group of parameters;

[0181] The health status assessment module 143 is used to determine the health status of the battery based on the degree of change in each set of parameters.

[0182] According to another specific embodiment of the present invention, reference is made to... Figure 9 The battery health status assessment device 100 also includes:

[0183] The root calculation module 144 is used to determine the root of the sum of squares of the relative average rates of change of multiple sets of parameters;

[0184] The root determination module 145 for the sum of squares is used to determine the health status of the battery based on the root of the sum of squares.

[0185] According to another specific embodiment of the present invention, reference is made to... Figure 10 The battery health status assessment device 100 also includes:

[0186] The AC current test module 121 is used to apply an AC current of a fixed frequency to the battery and test the voltage across the battery terminals when an AC current of a fixed frequency is applied to the battery.

[0187] The amplitude and phase offset calculation module 122 is used to obtain the amplitude of the current, the phase offset of the current, the amplitude of the voltage, and the phase offset of the voltage.

[0188] The ohmic internal resistance calculation module 123 is used to determine the ohmic internal resistance based on the amplitude of the current, the phase shift of the current, the amplitude of the voltage, and the phase shift of the voltage.

[0189] According to another specific embodiment of the present invention, reference is made to... Figure 11 The battery health status assessment device 100 also includes:

[0190] The charging / discharging module 124 is used to charge or discharge the battery at a constant current and then stop it.

[0191] The voltage acquisition module 125 is used to test the voltage across the battery at the first moment and the second moment, which correspond to the first voltage and the second voltage, respectively. The first moment is the moment when constant current charging or constant current discharging stops, and the second moment is the 8th to 12th ms moment when constant current charging or constant current discharging stops.

[0192] The electrochemical transfer resistance calculation module 126 is used to determine the sum of the ohmic internal resistance and the electrochemical transfer internal resistance based on the difference between the second voltage and the first voltage.

[0193] Thirdly, refer to Figure 12 The present invention also discloses an electronic device 200, including a memory 201, a processor 202, and a computer program stored in the memory 201 and executable on the processor 202. When the processor 202 executes the computer program, it implements the above-mentioned method for judging the health status of the battery.

[0194] Using the above technical solution, before fitting the equivalent circuit model, the two core parameters with deterministic physical significance—ohmic internal resistance and electrochemical transfer internal resistance—have been accurately obtained. Based on the correspondence between the components in the equivalent circuit model and the internal physical characteristics of the battery, fixed constraints are further established: first, the ohmic internal resistance is equal to the first resistance in the model; second, the sum of the second and third resistances in the model equals the electrochemical transfer internal resistance. These fixed constraints, by clearly defining the mapping relationship between known parameters and model parameters, directly reduce the number of unknown variables in the voltage and time functions corresponding to the equivalent circuit model, thereby reducing the degrees of freedom in the fitting process. This fundamentally avoids the problem of mathematical fitting results deviating from the actual physical characteristics of the battery due to too many dependent variables, thus preventing overfitting. Therefore, the fitted parameters can truly and accurately reflect the dynamic process and polarization evolution law of the internal electrochemical reaction of the battery, significantly improving the accuracy of parameter identification in the equivalent circuit model, providing reliable parameter support for the quantitative determination of battery health status, and ultimately effectively improving the accuracy of battery health status assessment.

[0195] Fourthly, the present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described method for determining the health status of a battery.

[0196] Using the above technical solution, before fitting the equivalent circuit model, the two core parameters with deterministic physical significance—ohmic internal resistance and electrochemical transfer internal resistance—have been accurately obtained. Based on the correspondence between the components in the equivalent circuit model and the internal physical characteristics of the battery, fixed constraints are further established: first, the ohmic internal resistance is equal to the first resistance in the model; second, the sum of the second and third resistances in the model equals the electrochemical transfer internal resistance. These fixed constraints, by clearly defining the mapping relationship between known parameters and model parameters, directly reduce the number of unknown variables in the voltage and time functions corresponding to the equivalent circuit model, thereby reducing the degrees of freedom in the fitting process. This fundamentally avoids the problem of mathematical fitting results deviating from the actual physical characteristics of the battery due to too many dependent variables, thus preventing overfitting. Therefore, the fitted parameters can truly and accurately reflect the dynamic process and polarization evolution law of the internal electrochemical reaction of the battery, significantly improving the accuracy of parameter identification in the equivalent circuit model, providing reliable parameter support for the quantitative determination of battery health status, and ultimately effectively improving the accuracy of battery health status assessment.

[0197] The following is a detailed explanation using specific examples:

[0198] S1: A function that obtains the voltage and time across the battery terminals. The function of the voltage V(t) and time t across the battery terminals corresponds to the equivalent circuit model of the battery, and the parameters of the function correspond to the physical quantities in the equivalent circuit model.

[0199] Equivalent circuit model such as Figure 1 As shown, the equivalent circuit model includes:

[0200] First resistor Used to characterize the ohmic internal resistance of a battery The first circuit unit, and the first resistor. Electrical connection, and includes a second resistor. The first circuit unit is used to characterize the polarization process caused by the electrochemical reaction at the negative electrode of the battery. The first circuit unit and the first resistor... Series connection. The first circuit unit includes a second resistor. It also includes the second resistor The first capacitor, C1, is connected in parallel. This first circuit unit reflects the polarization effect generated at the negative electrode during the electrochemical reaction, and is used to quantify the intensity of the negative electrode polarization process. The second circuit unit, electrically connected to the first circuit unit, includes a third resistor. The second circuit unit is used to characterize the polarization process caused by the positive electrode electrochemical reaction of the battery. The second circuit unit includes a third resistor. It also includes the third resistor The second capacitor C2 is connected in parallel. The second circuit unit reflects the polarization effect generated at the positive electrode during the electrochemical reaction process, and is used to quantify the intensity of the positive electrode polarization process. The second resistor... With the third resistor The sum of these two factors constitutes the electrochemical transfer resistance. The electrochemical transfer resistance is the sum of the polarization resistance caused by the positive electrode electrochemical reaction and the polarization resistance caused by the negative electrode electrochemical reaction.

[0201] Battery voltage The functional relationship between time t and the time t is:

[0202] (Formula 1)

[0203] in, This indicates the open-circuit voltage of the battery. This represents the value of the DC constant current. Indicates the first resistance. Indicates the second resistor. Indicates the first capacitor. Indicates the third resistor. This indicates the second capacitor.

[0204] S2: Obtain the ohmic internal resistance of the battery. and electrochemical transfer resistance Among them, obtaining the ohmic internal resistance The values ​​can be obtained through a single-frequency alternating current test. Specifically, after the battery has been left to stand, a single-frequency alternating current test is performed, and the alternating voltage and current are fitted using formulas 2 and 3.

[0205] (Formula 2)

[0206] Where V represents the voltage of a single-frequency alternating current test. This represents the DC offset of the voltage. f represents the voltage amplitude, and f represents the voltage frequency. This represents the phase shift of the voltage, and x represents time.

[0207] (Formula 3)

[0208] Where I represents the current in a single-frequency alternating current test. Indicates the DC offset of the current. f represents the amplitude of the current, and f represents the frequency of the current. This represents the phase shift of the current, and x represents time.

[0209] The ohmic resistance can be obtained using Formula 4. :

[0210] (Formula 4)

[0211] Then, based on the amplitude of the current Phase shift of the current The amplitude of the voltage Phase shift of voltage Determine the ohmic internal resistance .

[0212] The electrochemical transfer resistance is determined by obtaining the sum of the ohmic polarization and the electrochemical transfer polarization.

[0213] (Formula 5)

[0214] in, This represents the sum of ohmic polarization and electrochemical transferred polarization. Indicates Ohmic polarization, V1 represents electrochemical transfer polarization, V2 represents the voltage at the second moment, and V1 represents the voltage at the first moment.

[0215] Based on the sum of Ohmic polarization and electrochemical transfer polarization Current I1 and internal resistance in ohms The electrochemical transfer resistance is obtained according to Formula 6. .

[0216] (Formula 6)

[0217] in, Indicates the electrochemical transfer resistance. I1 represents the sum of ohmic polarization and electrochemical transfer polarization, and represents the current. This represents the internal resistance of the Ohm.

[0218] According to Ohm's internal resistance Determine the first resistor Specifically, the ohmic internal resistance The first internal resistance is R1. The second resistance is determined based on the electrochemical transfer internal resistance. and the third resistor The sum. Specifically, the electrochemical transfer internal resistance. For the second resistor With the third resistor sum.

[0219] Data on the voltage and time at both ends of the battery, and the internal resistance in ohms. and electrochemical transfer resistance Substitute into Formula 1:

[0220] (Formula 1)

[0221] in, This indicates the open-circuit voltage of the battery. This represents the value of the DC constant current. Indicates the first resistance. Indicates the second resistor. Indicates the first capacitor. Indicates the third resistor. This indicates the second capacitor.

[0222] Determine the parameters of the function, including the first resistance. Second resistor and the third resistor .

[0223] S4: Determine the battery's health status based on the parameters.

[0224] Calculate the first resistance according to formulas 7 and 8. The relative average rate of change.

[0225] (Formula 7)

[0226] (Formula 8)

[0227] in, Represents the first resistance in the nth power. The average of the fitted values, Indicates the first resistor The fitted value of the i-th iteration, Indicates the first resistor The fitted value for the nth iteration. Indicates the first resistor The relative average rate of change.

[0228] Calculate the second resistor according to formulas 9 and 10. The relative average rate of change.

[0229] (Formula 9)

[0230] (Formula 10)

[0231] in, Represents the second resistor of the nth power. The average of the fitted values, Indicates the second resistor The fitted value of the i-th iteration, Indicates the second resistor The fitted value for the nth iteration. Indicates the second resistor The relative average rate of change.

[0232] Calculate the third resistor using formulas 11 and 12. The relative average rate of change.

[0233] (Formula 11)

[0234] (Formula 12)

[0235] in, Represents the third resistance of the nth power The average of the fitted values, Indicates the third resistor The fitted value of the i-th iteration, Indicates the third resistor The fitted value for the nth iteration. Indicates the third resistor The relative average rate of change.

[0236] S431: Determine the root of the sum of squares of the relative average rates of change of multiple sets of parameters. Specifically, as shown in Formula 15, calculate the first resistance. relative average rate of change Second resistor relative average rate of change Third resistor relative average rate of change The root of the sum of squares .

[0237] (Formula 15)

[0238] in, The first resistor Second resistor and the third resistor The root of the sum of squares of the relative average rate of change Also known as the decision number.

[0239] The first resistance was obtained from the test. relative average rate of change Second resistor relative average rate of change Third resistor relative average rate of change The result is N(n), the root of the sum of squares of the relative average rates of change of each parameter, as shown in the figure. Figures 13-16 .

[0240] Figure 13 The first resistor relative average rate of change This reflects the change in Ohmic internal resistance. From Figure 13 It can be seen that, in cycles 1 to 182, the first resistor... relative average rate of change Maintain stability. 183rd charging cycle, first resistance. relative average rate of change The value increases dramatically beyond the preset threshold A1. During the 183rd to 191st charge-discharge cycles, the first resistance... relative average rate of change A dramatic increase, first resistance relative average rate of change The first resistor in the 183rd to 191st cycles relative average rate of change The derivative is much greater than the derivative of the relative average rate of change from 1 to 182. This indicates that battery degradation occurs around the 183rd charging cycle.

[0241] Figure 14 For the second resistor relative average rate of change This reflects the change in the internal resistance of the negative electrode's electrochemical transfer. From... Figure 14 It can be seen that, in cycles 1 to 181, the second resistor... relative average rate of change Maintain stability. 182nd charging cycle, second resistor. relative average rate of change The value increases dramatically beyond the preset threshold A2. During the 182nd to 191st charge-discharge cycles, the second resistor... relative average rate of change The second resistance increases dramatically. relative average rate of change The second resistor in the 182nd to 191st cycles relative average rate of change The derivative of the value is much greater than the derivative of the relative average rate of change from 1 to 181. This indicates that battery degradation occurs around the 182nd charge cycle.

[0242] Figure 15 For the third resistor relative average rate of change This reflects the change in the internal resistance of the positive electrode's electrochemical transfer. From... Figure 14 It can be seen that, in cycles 1 to 181, the third resistor... relative average rate of change Maintaining stability. 182nd charging cycle, third resistor. relative average rate of change The value increases dramatically beyond the preset threshold A3. This occurs during the 182nd to 191st charge-discharge cycles, specifically in the third resistor. relative average rate of change A dramatic increase, third resistor relative average rate of change The third resistor in the 182nd to 191st cycles relative average rate of change The derivative of the value is much greater than the derivative of the relative average rate of change from 1 to 181. This indicates that battery degradation occurs around the 182nd charge cycle.

[0243] refer to Figure 16 According to the first resistor Second resistor and the third resistor The root of the sum of squares of the relative average rate of change Determine the battery's health status. Determine the first resistance. Second resistor and the third resistor The root of the sum of squares of the relative average rate of change Does it exceed the preset threshold Y? If yes, the battery is unhealthy; if no, the battery is healthy. From Figure 16 It can be seen that, The first resistor Second resistor and the third resistor The root of the sum of squares of the relative average rate of change This is also known as the judgment number being greater than the preset judgment threshold Y after the 182nd charging cycle. A surge occurred after 182 charge cycles, resulting in a sharp drop in battery capacity. In the 182nd charge cycle, the battery capacity decreased from the initial 14.5 Ah to 11.8 Ah, representing only 81% of the initial capacity, indicating an unhealthy battery condition. This demonstrates that the battery is unhealthy after the 182nd charge cycle. The method of this invention allows for accurate, timely, and effective assessment of battery health by accurately fitting the model parameters in the equivalent circuit model.

[0244] While the present invention has been illustrated and described with reference to certain preferred embodiments, those skilled in the art should understand that the above description is a further detailed explanation of the invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the invention to these descriptions. Various changes in form and detail can be made by those skilled in the art, including several simple deductions or substitutions, without departing from the spirit and scope of the invention.

Claims

1. A method for judging the health status of a battery, characterized in that, include: A function is used to obtain the voltage and time across the battery terminals. This function corresponds to an equivalent circuit model of the battery. The parameters of the function correspond to physical quantities in the equivalent circuit model, which includes: The first resistor is used to characterize the ohmic internal resistance of the battery; A first circuit unit, electrically connected to the first resistor and including a second resistor, is used to characterize the polarization process caused by the negative electrode electrochemical reaction of the battery. The second circuit unit is electrically connected to the first circuit unit and includes a third resistor. The second circuit unit is used to characterize the polarization process caused by the positive electrode electrochemical reaction of the battery. The sum of the second resistor and the third resistor is the electrochemical transfer internal resistance. Obtain the ohmic internal resistance and electrochemical transfer internal resistance of the battery, determine the first resistance based on the ohmic internal resistance, and determine the sum of the second resistance and the third resistance based on the electrochemical transfer internal resistance; A DC constant current is applied to the battery using a voltage source to obtain data on the voltage and time across the battery. Based on the relationship between the ohmic internal resistance and the first resistance, and the relationship between the electrochemical transfer internal resistance and the second and third resistances, the data on the voltage and time across the battery, the ohmic internal resistance, and the electrochemical transfer internal resistance are substituted into the functional relationship between the voltage and time across the battery. The functional relationship between the voltage and time across the battery corresponding to the equivalent circuit model is fitted to determine the parameters of the function. The parameters include the first resistance, the second resistance, and the third resistance. The health status of the battery is determined based on the parameters.

2. The method for judging the health status of a battery as described in claim 1, characterized in that, The step of determining the health status of the battery based on the parameters includes: By applying the same DC constant current to the battery n times through the voltage source, multiple sets of parameters are obtained. Each set of parameters includes n fitted values ​​of the same parameter, where n is a positive integer greater than or equal to 2. Calculate the degree of change of each group of parameters; The health status of the battery is determined based on the degree of change in each set of parameters.

3. The method for judging the health status of a battery as described in claim 2, characterized in that, The degree of change is the relative average rate of change, which is the rate of change of the nth parameter relative to the average value of the group of parameters.

4. The method for judging the health status of a battery as described in claim 3, characterized in that, The step of determining the battery's health status based on the degree of change of each set of parameters includes: Determine the root of the sum of squares of the relative average rates of change of multiple parameters; The health status of the battery is determined based on the root of the sum of squares.

5. The method for judging the health status of a battery as described in claim 1, characterized in that, The first circuit unit further includes a first capacitor, which is connected in parallel with the second resistor; The second circuit unit further includes a second capacitor, which is connected in parallel with the third resistor; The parameters also include the first capacitor and the second capacitor.

6. The method for judging the health status of a battery as described in claim 5, characterized in that, The functional relationship between the voltage across the battery and time is as follows: (Formula 1) in, This indicates the open-circuit voltage of the battery. This represents the current value of the DC constant current. This represents the first resistor. This indicates the second resistor. This refers to the first capacitor. This refers to the third resistor. This refers to the second capacitor.

7. The method for judging the health status of a battery as described in claim 1, characterized in that, The process of obtaining the ohmic internal resistance and electrochemical transfer internal resistance of the battery includes: An alternating current of a fixed frequency is applied to the battery, and the voltage across the battery is tested when the alternating current of the fixed frequency is applied to the battery. The amplitude of the current, the phase shift of the current, the amplitude of the voltage, and the phase shift of the voltage are obtained. The ohmic internal resistance is determined based on the amplitude of the current, the phase shift of the current, the amplitude of the voltage, and the phase shift of the voltage.

8. The method for judging the health status of a battery as described in claim 1, characterized in that, Determining the ohmic internal resistance and electrochemical transfer internal resistance of the battery includes: Stop charging or discharging the battery at a constant current after it has been charged or discharged at a constant current. The voltages across the battery are tested at the first and second time points, respectively, which correspond to the first voltage and the second voltage. The first time point is the moment when the constant current charging or constant current discharging stops, and the second time point is the 8th to 12th ms moment when the constant current charging or constant current discharging stops. The sum of the ohmic internal resistance and the electrochemical transfer internal resistance is determined based on the difference between the second voltage and the first voltage.

9. A device for judging the health status of a battery, characterized in that, include: A function acquisition module is used to acquire functions representing the voltage and time at the battery terminals. These functions correspond to an equivalent circuit model of the battery. The parameters of the function correspond to physical quantities in the equivalent circuit model. The equivalent circuit model includes: a first resistor characterizing the ohmic internal resistance of the battery; a first circuit unit electrically connected to the first resistor and including a second resistor, the first circuit unit characterizing the polarization process caused by the negative electrode electrochemical reaction of the battery; and a second circuit unit electrically connected to the first circuit unit and including a third resistor, the second circuit unit characterizing the polarization process caused by the positive electrode electrochemical reaction of the battery. The sum of the second resistor and the third resistor is the electrochemical transfer internal resistance. An internal resistance determination module is used to obtain the ohmic internal resistance and electrochemical transfer internal resistance of the battery, determine the first resistance based on the ohmic internal resistance, and determine the sum of the second resistance and the third resistance based on the electrochemical transfer internal resistance. A DC testing module is used to apply a constant DC current to the battery through a voltage source, acquire data on the voltage and time across the battery, and, based on the relationship between the ohmic internal resistance and the first resistance, and the relationship between the electrochemical transfer internal resistance and the second and third resistances, substitute the data on the voltage and time across the battery, the ohmic internal resistance, and the electrochemical transfer internal resistance into the functional relationship of the voltage and time across the battery, fit the functional relationship of the voltage and time across the battery corresponding to the equivalent circuit model, and determine the parameters of the function, which include the first resistance, the second resistance, and the third resistance. A battery health status assessment module is used to determine the health status of the battery based on the parameters.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the battery health status judgment method as described in any one of claims 1 to 8.

11. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the battery health status judgment method as described in any one of claims 1 to 8.

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