CN117388724A - Battery self-discharge detection method, computer-readable storage medium and electronic equipment - Google Patents

Abstract

The present invention relates to the field of battery technology, and specifically provides a battery self-discharge detection method, a computer-readable storage medium and an electronic device, aiming to solve the problem that existing self-discharge detection methods have limited applicable scenarios and cannot effectively identify self-discharge. To this end, the battery self-discharge detection method of the present invention forms a battery pack by connecting multiple batteries to be detected with the same initial state of charge in series, and calculates the total current of the battery pack at different times during the charging process and the rest period after charging. The voltage data set of each battery to be tested in the battery pack is used as the input of the second-order equivalent battery model, and the least squares method is used to fit the parameters in the second-order equivalent battery model; according to the simulated data corresponding to the battery to be tested in the battery pack, The fitting parameters corresponding to the combined parameters and all the batteries to be tested in the battery pack determine whether self-discharge occurs in the battery to be tested. It avoids the problem of limited applicable range and can effectively detect battery self-discharge.

Description

Battery self-discharge detection method, computer-readable storage medium and electronic equipment

Technical field

The invention relates to the field of battery technology, and specifically provides a battery self-discharge detection method, a computer-readable storage medium and an electronic device.

Background technique

With the gradual popularization of new energy vehicles, people have put forward higher and higher requirements for the actual endurance capability that vehicle batteries can provide. Self-discharge, as one of the important factors affecting the capacity retention capacity of the battery pack, needs to be monitored in real time to determine the health status of the battery pack by monitoring self-discharge conditions, promptly discover battery packs with abnormal self-discharge batteries, and avoid battery packs that have abnormal self-discharge during use. Failures can cause a bad experience for users and even pose safety risks.

In the prior art, the relevant parameters of a single battery, such as the state of charge, are usually used to identify whether the battery is discharged. Specifically, the open circuit voltage of the battery is first determined, and the state of charge of the battery is determined based on the correspondence between the open circuit voltage and the state of charge. Electrical state to identify self-discharge, but this method is applicable to limited self-discharge detection scenarios. For example, for LFP batteries (lithium iron phosphate batteries), the open circuit voltage-state of charge curve is relatively flat, and most of the open circuit voltage can be mapped to the charge The state range is large, so self-discharge cannot be effectively identified based on the corresponding relationship between open circuit voltage and state of charge, which brings inconvenience and difficulty to self-discharge detection of LFP batteries.

Contents of the invention

The present invention aims to solve the above technical problems, that is, to solve the problem that the existing self-discharge detection method has limited applicable scenarios and cannot effectively identify self-discharge.

In a first aspect, the present invention provides a battery self-discharge detection method, which includes:

The total current of the battery pack at different times during the charging process and the voltage of each battery to be detected in the battery pack at different times during the rest period after charging are obtained in real time, and a voltage data set of each battery to be detected is obtained. The group includes a plurality of batteries to be tested connected in series, and the initial state of charge of each battery to be tested is the same;

The voltage data set of each battery to be detected and the total current of the battery pack at different times are input into a second-order equivalent battery model, and the least squares method is used to calculate the second-order equivalent battery model. The parameters are fitted to obtain at least one fitting parameter of each of the batteries to be detected;

Whether the battery to be detected self-discharges is determined based on the fitting parameters corresponding to the battery to be detected in the battery pack and the fitting parameters corresponding to all the batteries to be detected in the battery pack.

In some embodiments, when there is only one kind of fitting parameter, the fitting parameter corresponding to the battery to be detected in the battery pack and the fitting parameters corresponding to all batteries to be detected in the battery pack are determined. Describe whether the battery to be tested is self-discharging, including:

Calculate the average value of the fitting parameters according to the fitting parameters of all batteries to be detected in the battery pack;

Whether the battery to be detected self-discharges is determined based on the fitting parameters of the battery to be detected and the average value of the fitting parameters.

In some embodiments, the fitting parameters include open circuit voltage, ohmic internal resistance or electrochemical polarization internal resistance, and the battery to be detected is determined according to the fitting parameters of the battery to be detected and the average value of the fitting parameters. Whether self-discharge occurs, including:

When the fitting parameter is the open circuit voltage, determine the state of charge corresponding to the open circuit voltage of the battery to be detected and the reference state of charge corresponding to the average value of the open circuit voltage according to the open circuit voltage-state of charge relationship table, and determine Whether the difference between the state of charge corresponding to the battery to be detected and the reference state of charge is within a preset range; if so, it is determined that the battery to be detected has not self-discharged; if not, it is determined that the battery to be detected is not self-discharged Self-discharge occurs;

When the fitting parameter is the ohmic internal resistance, determine whether the difference between the ohmic internal resistance corresponding to the battery to be detected and the average ohmic internal resistance is less than the first preset threshold; if so, determine whether the battery to be detected has occurred. Self-discharge; if not, determine that the battery to be detected does not self-discharge;

When the fitting parameter is electrochemical polarization internal resistance, determine whether the difference between the electrochemical polarization internal resistance corresponding to the battery to be detected and the average electrochemical polarization internal resistance is less than the second preset threshold; if If yes, it is determined that self-discharge has occurred in the battery to be detected; if not, it is determined that self-discharge has not occurred in the battery to be detected.

In some embodiments, when there are multiple fitting parameters, the fitting parameters corresponding to the battery to be detected in the battery pack and the fitting parameters corresponding to all batteries to be detected in the battery pack are determined. Describe whether the battery to be tested is self-discharging, including:

Determine the average value of the fitting parameters corresponding to each fitting parameter of all batteries to be detected in the battery pack;

For each fitting parameter, determine whether the fitting parameter of the battery to be detected and the corresponding average value of the fitting parameter meet the corresponding first preset condition;

And/or, perform a linear polynomial combination on at least two fitting parameters of each battery to be detected in the battery pack to obtain the characteristic value of each battery to be detected; according to the characteristic value of the battery to be detected and the The characteristic values of all batteries to be detected in the battery pack are determined to determine whether the characteristic values of the batteries to be detected meet the second preset condition;

When any one of the first preset condition and the second preset condition is met, it is determined that the battery to be detected has self-discharge; when neither the first preset condition nor the second preset condition is met, it is determined that the battery to be detected has self-discharge. Check that the battery does not self-discharge.

In some embodiments, when the fitting parameter is an open circuit voltage, and the difference between the state of charge corresponding to the open circuit voltage of the battery to be detected and the reference state of charge corresponding to the average value of the open circuit voltage exceeds the preset range When, it is determined that the first preset condition is met;

When the fitting parameter is ohmic internal resistance, and the difference between the ohmic internal resistance corresponding to the battery to be detected and the average ohmic internal resistance is less than the first preset threshold, it is determined that the first preset condition is met;

When the fitting parameter is the electrochemical polarization internal resistance, and the difference between the electrochemical polarization internal resistance corresponding to the battery to be detected and the average electrochemical polarization internal resistance is less than the second preset threshold, it is determined that the the first preset condition.

In some embodiments, the characteristic value of each battery to be detected is obtained by performing a linear polynomial combination on the fitting parameters of each battery to be detected in the battery pack using the following expression:

Among them, S represents the characteristic value, R ₀ represents the ohmic internal resistance, R ₁ represents the electrochemical polarization internal resistance, C ₁ represents the electrochemical polarization capacitance, R ₂ represents the concentration polarization internal resistance, and C ₂ represents the concentration polarization Capacitance, a ₀ , a ₁ , a ₂ , a ₃ , a ₄ , b ₀ , b ₁ , b ₂ , b ₃ and b ₄ are constants.

In some embodiments, the fitting parameters include ohmic internal resistance and at least one polarization internal resistance, the polarization internal resistance includes electrochemical polarization internal resistance and concentration polarization internal resistance, and the respective values are At least two fitting parameters of each battery to be tested in the battery pack are combined with a linear polynomial to obtain the characteristic value of each battery to be tested, including:

The ohmic internal resistance and the at least one polarization internal resistance of each battery to be detected in the battery pack are respectively summed to obtain the characteristic value of each battery to be detected.

In some embodiments, determining whether the characteristic value of the battery to be tested meets the second preset condition based on the characteristic value of the battery to be tested and the characteristic values of all batteries to be tested in the battery pack includes:

According to the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack, determine whether the characteristic value of the battery to be detected is an outlier; if so, determine the characteristic value of the battery to be detected The second preset condition is met; if not, it is determined that the characteristic value of the battery to be detected does not meet the second preset condition.

In some embodiments, determining whether the characteristic value of the battery to be detected is an outlier based on the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack includes:

Determine the median characteristic value from the characteristic values of all batteries to be tested and calculate the absolute median difference based on the characteristic values of all batteries to be tested;

Determine whether the characteristic value of the battery to be detected is less than the difference between the median characteristic value and the first preset multiple absolute median difference. If so, determine that the characteristic value of the battery to be detected is an outlier; if not, It is determined that the characteristic value of the battery to be detected is not an outlier.

In some embodiments, determining whether the characteristic value of the battery to be detected is an outlier based on the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack includes:

Calculate the average characteristic value based on the characteristic values of all batteries to be detected, and calculate the standard deviation of the characteristic values based on the characteristic values of the remaining batteries to be detected in the battery pack except the battery to be detected selected for detection;

Determine whether the characteristic value of the selected battery to be detected is less than the difference between the average characteristic value and the second preset multiple characteristic value standard deviation; if so, determine that the characteristic value of the selected battery to be detected is an outlier. ; If not, determine that the characteristic value of the battery to be detected selected for detection is not an outlier.

In a second aspect, the present invention provides a computer-readable storage medium, a computer program stored in the computer-readable storage medium, and when the computer program is executed by a processor, the battery self-discharge described in any one of the above is realized. Detection method.

In a third aspect, the present invention provides an electronic device, which includes a memory and a processor. A computer program is stored in the memory. When the computer program is executed by the processor, the battery according to any one of the above is implemented. Self-discharge detection method.

Solution 1. A battery self-discharge detection method, characterized by including:

The total current of the battery pack at different times during the charging process and the voltage of each battery to be detected in the battery pack at different times during the rest period after charging are obtained in real time, and a voltage data set of each battery to be detected is obtained. The group includes a plurality of batteries to be tested connected in series, and the initial state of charge of each battery to be tested is the same;

The voltage data set of each battery to be detected and the total current of the battery pack at different times are input into a second-order equivalent battery model, and the least squares method is used to calculate the second-order equivalent battery model. The parameters are fitted to obtain at least one fitting parameter of each of the batteries to be detected;

Whether the battery to be detected self-discharges is determined based on the fitting parameters corresponding to the battery to be detected in the battery pack and the fitting parameters corresponding to all the batteries to be detected in the battery pack.

Option 2. The method according to Option 1, characterized in that when there is only one fitting parameter, the fitting parameter corresponding to the battery to be detected in the battery pack and all the parameters to be detected in the battery pack are The fitting parameters corresponding to the detection battery determine whether self-discharge occurs in the battery to be detected, including:

Calculate the average value of the fitting parameters according to the fitting parameters of all batteries to be detected in the battery pack;

Whether the battery to be detected self-discharges is determined based on the fitting parameters of the battery to be detected and the average value of the fitting parameters.

Option 3. The method according to Option 2, characterized in that the fitting parameters include open circuit voltage, ohmic internal resistance or electrochemical polarization internal resistance. According to the fitting parameters of the battery to be detected and the fitting The average parameter value determines whether self-discharge occurs in the battery to be tested, including:

When the fitting parameter is the open circuit voltage, determine the state of charge corresponding to the open circuit voltage of the battery to be detected and the reference state of charge corresponding to the average value of the open circuit voltage according to the open circuit voltage-state of charge relationship table, and determine Whether the difference between the state of charge corresponding to the battery to be detected and the reference state of charge is within a preset range; if so, it is determined that the battery to be detected has not self-discharged; if not, it is determined that the battery to be detected is not self-discharged Self-discharge occurs;

When the fitting parameter is the ohmic internal resistance, determine whether the difference between the ohmic internal resistance corresponding to the battery to be detected and the average ohmic internal resistance is less than the first preset threshold; if so, determine whether the battery to be detected has occurred. Self-discharge; if not, determine that the battery to be detected does not self-discharge;

When the fitting parameter is electrochemical polarization internal resistance, determine whether the difference between the electrochemical polarization internal resistance corresponding to the battery to be detected and the average electrochemical polarization internal resistance is less than the second preset threshold; if If yes, it is determined that self-discharge has occurred in the battery to be detected; if not, it is determined that self-discharge has not occurred in the battery to be detected.

Option 4. The method according to Option 1, characterized in that when there are multiple fitting parameters, according to the fitting parameters corresponding to the battery to be detected in the battery pack and all the parameters to be detected in the battery pack The fitting parameters corresponding to the detection battery determine whether self-discharge occurs in the battery to be detected, including:

Determine the average value of the fitting parameters corresponding to each fitting parameter of all batteries to be detected in the battery pack;

For each fitting parameter, determine whether the fitting parameter of the battery to be detected and the corresponding average value of the fitting parameter meet the corresponding first preset condition;

And/or, perform a linear polynomial combination on at least two fitting parameters of each battery to be detected in the battery pack to obtain the characteristic value of each battery to be detected; according to the characteristic value of the battery to be detected and the The characteristic values of all batteries to be detected in the battery pack are determined to determine whether the characteristic values of the batteries to be detected meet the second preset condition;

When any one of the first preset condition and the second preset condition is met, it is determined that the battery to be detected has self-discharge; when neither the first preset condition nor the second preset condition is met, it is determined that the battery to be detected has self-discharge. Check that the battery does not self-discharge.

Option 5. The method according to Option 4, characterized in that when the fitting parameter is an open circuit voltage, and the state of charge corresponding to the open circuit voltage of the battery to be detected and the reference charge corresponding to the average value of the open circuit voltage When the difference in electrical status exceeds the preset range, it is determined that the first preset condition is met;

When the fitting parameter is ohmic internal resistance, and the difference between the ohmic internal resistance corresponding to the battery to be detected and the average ohmic internal resistance is less than the first preset threshold, it is determined that the first preset condition is met;

When the fitting parameter is the electrochemical polarization internal resistance, and the difference between the electrochemical polarization internal resistance corresponding to the battery to be detected and the average electrochemical polarization internal resistance is less than the second preset threshold, it is determined that the the first preset condition.

Option 6. The method according to Option 4, characterized by performing a linear polynomial combination on the fitting parameters of each battery to be detected in the battery pack using the following expression to obtain the characteristic value of each battery to be detected:

Among them, S represents the characteristic value, R ₀ represents the ohmic internal resistance, R ₁ represents the electrochemical polarization internal resistance, C ₁ represents the electrochemical polarization capacitance, R ₂ represents the concentration polarization internal resistance, and C ₂ represents the concentration polarization Capacitance, a ₀ , a ₁ , a ₂ , a ₃ , a ₄ , b ₀ , b ₁ , b ₂ , b ₃ and b ₄ are constants.

Option 7. The method according to Option 4, characterized in that the fitting parameters include ohmic internal resistance and at least one polarization internal resistance, and the polarization internal resistance includes electrochemical polarization internal resistance and concentration difference electrode. To reduce the internal resistance, perform a linear polynomial combination on at least two fitting parameters of each battery to be tested in the battery pack to obtain the characteristic value of each battery to be tested, including:

The ohmic internal resistance and the at least one polarization internal resistance of each battery to be detected in the battery pack are respectively summed to obtain the characteristic value of each battery to be detected.

Option 8. The method according to Option 6 or 7, characterized in that the characteristics of the battery to be detected are determined based on the characteristic values of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack. Whether the value meets the second preset condition, including:

According to the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack, determine whether the characteristic value of the battery to be detected is an outlier; if so, determine the characteristic value of the battery to be detected The second preset condition is met; if not, it is determined that the characteristic value of the battery to be detected does not meet the second preset condition.

Option 9. The method according to Option 8, characterized in that, based on the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack, it is determined whether the characteristic value of the battery to be detected is an isolated Group values include:

Determine the median characteristic value from the characteristic values of all batteries to be tested and calculate the absolute median difference based on the characteristic values of all batteries to be tested;

Determine whether the characteristic value of the battery to be detected is less than the difference between the median characteristic value and the first preset multiple absolute median difference. If so, determine that the characteristic value of the battery to be detected is an outlier; if not, It is determined that the characteristic value of the battery to be detected is not an outlier.

Option 10. The method according to Option 8, characterized in that, based on the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack, it is determined whether the characteristic value of the battery to be detected is an isolated Group values include:

Calculate the average characteristic value based on the characteristic values of all batteries to be detected, and calculate the standard deviation of the characteristic values based on the characteristic values of the remaining batteries to be detected in the battery pack except the battery to be detected selected for detection;

Determine whether the characteristic value of the selected battery to be detected is less than the difference between the average characteristic value and the second preset multiple characteristic value standard deviation; if so, determine that the characteristic value of the selected battery to be detected is an outlier. ; If not, determine that the characteristic value of the battery to be detected selected for detection is not an outlier.

Embodiment 11. A computer-readable storage medium, characterized in that a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the battery according to any one of Embodiments 1 to 10 is implemented. Self-discharge detection method.

Embodiment 12. An electronic device, characterized in that it includes a memory and a processor. A computer program is stored in the memory. When the computer program is executed by the processor, the method described in any one of Embodiments 1 to 10 is implemented. Battery self-discharge detection method.

When the above technical solution is adopted, the present invention connects multiple batteries to be detected with the same initial charge state in series to form a battery pack, and obtains in real time the total current of the battery pack at different times during the charging process and the battery during the rest period after charging. The voltage data set of each battery to be detected in the group; construct a second-order equivalent battery model, using the voltage data set of each battery and the total current of the battery group at different times as the input of the second-order equivalent battery model, using the minimum The square method is used to fit the parameters in the second-order equivalent battery model to obtain at least one fitting parameter for each battery to be tested; according to the fitting parameters corresponding to the battery to be tested in the battery pack and all the parameters to be tested in the battery pack The fitting parameters corresponding to the battery determine whether self-discharge occurs in the battery to be detected. This method determines whether self-discharge occurs in the battery to be detected by analyzing and comparing the fitting parameters of a single battery to be detected in the battery pack and the fitting parameters of all batteries to be detected in the battery pack, and avoids the correlation based on the battery to be detected alone. Parameters for self-discharge identification can be applied to problems with limited scope or low identification accuracy, and can effectively detect battery self-discharge.

Description of the drawings

The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic flow chart of a battery self-discharge detection method provided by an embodiment of the present invention;

Figure 2 is a circuit schematic diagram of the second-order equivalent battery model provided by the present invention;

Figure 3 is a schematic flowchart of a method for determining whether self-discharge occurs in a battery to be detected according to an embodiment of the present invention;

FIG. 4 is a schematic flowchart of another method for determining whether self-discharge occurs in a battery to be detected according to an embodiment of the present invention.

Detailed ways

Some embodiments of the invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of the present invention.

In the prior art, the relevant parameters of a single battery, such as the state of charge, are usually used to identify whether the battery is discharged. Specifically, the open circuit voltage of the battery is first determined, and the state of charge of the battery is determined based on the correspondence between the open circuit voltage and the state of charge. Electrical state to identify self-discharge, but this method is applicable to limited self-discharge detection scenarios. For example, for LFP batteries (lithium iron phosphate batteries), the open circuit voltage-state of charge curve is relatively flat, and most of the open circuit voltage can be mapped to the charge The state range is large, so self-discharge cannot be effectively identified based on the corresponding relationship between open circuit voltage and state of charge, which brings inconvenience and difficulty to self-discharge detection of LFP batteries.

In view of this, the present invention provides a battery self-discharge detection method. By connecting multiple batteries to be detected with the same initial state of charge in series to form a battery pack, the total current of the battery pack at different times during the charging process and the end of charging are obtained in real time. The voltage data set of each battery to be detected in the battery pack during the post-rest period; construct a second-order equivalent battery model, using the voltage data set of each battery and the total current of the battery pack at different times as the second-order equivalent battery model As input, the least squares method is used to fit the parameters in the second-order equivalent battery model to obtain at least one fitting parameter for each battery to be tested; according to the fitting parameters corresponding to the battery to be tested in the battery pack and the battery The fitting parameters corresponding to all batteries to be tested in the group determine whether self-discharge occurs in the battery to be tested. This method determines whether self-discharge occurs in the battery to be detected by analyzing and comparing the fitting parameters of a single battery to be detected in the battery pack and the fitting parameters of all batteries to be detected in the battery pack, and avoids the correlation based on the battery to be detected alone. Parameters for self-discharge identification can be applied to problems with limited scope or low identification accuracy, and can effectively detect battery self-discharge.

Referring to Figure 1, Figure 1 is a schematic flow chart of a battery self-discharge detection method provided by an embodiment of the present invention, which may include:

Step S11: Obtain in real time the total current of the battery pack at different times during the charging process and the voltage of each battery to be detected in the battery pack at different times during the rest period after charging, and obtain a voltage data set of each battery to be detected. The battery pack includes Multiple batteries to be tested are connected in series, and the initial state of charge of each battery to be tested is the same;

Step S12: Input the voltage data set of each battery to be detected and the total current of the battery pack at different times into the second-order equivalent battery model, and use the least squares method to fit the parameters in the second-order equivalent battery model to Obtain at least one fitting parameter for each battery to be tested;

Step S13: Determine whether the battery to be detected self-discharges according to the fitting parameters corresponding to the battery to be detected in the battery pack and the fitting parameters corresponding to all the batteries to be detected in the battery pack.

In the embodiment of the present invention, multiple batteries to be detected with the same initial state of charge can be connected in series to form a battery pack.

In some embodiments, step S11 can be specifically to charge the battery pack, and obtain in real time the constant current of the battery pack at different times during the charging process and the voltage of each battery to be detected in the battery pack at different times during the rest period after charging, to obtain Voltage data set for each battery to be tested.

As an example, the initial state of charge can be used as the upper limit of charging to perform constant current charging on the battery pack, and the constant current of the battery pack during the charging process can be collected in real time. The voltage data set of each battery to be tested can be obtained by collecting the voltage in real time during the rest period from the end of charging to the complete voltage stabilization. It should be noted that in other embodiments, the battery pack can also be charged with non-constant current, and the total current at different moments in the current stabilization stage during the charging process can be obtained.

In the embodiment of the present invention, as shown in Figure 2, the circuit of the second-order equivalent battery model includes the following parameters: open circuit voltage E(t), charging current i(t) of the battery pack, ohmic internal resistance R ₀ , Electrochemical polarization internal resistance R ₁ , electrochemical polarization capacitance C ₁ , concentration difference polarization internal resistance R ₂ , concentration difference polarization capacitance C ₂ and the terminal voltage V(t) of the battery to be detected.

In some embodiments, step S12 may specifically include inputting the voltage data set u(t) of each battery to be detected and the total current of the battery pack at different times into a second-order equivalent battery model, where the constant current of the battery pack or The total current in the current stabilization stage is used as the charging current i(t) of the battery pack to avoid voltage mutations caused by current changes, which may lead to polarization and interfere with the results of battery self-discharge detection.

In some embodiments, in step S12, the confidence region algorithm can be used to perform least squares fitting on the parameters in the second-order equivalent battery model, and the terminal voltage of the battery to be detected is output according to the fitted second-order equivalent battery model. The fitting curve of V(t) and the fitting curve of the voltage data set u(t) of the battery to be detected determine whether the stop condition of the model iteration is met, and when the model meets the iteration stop condition, the minimum value of each battery to be detected is obtained. A fitting parameter. As an example, when the standard residual of the fitting curve of the terminal voltage V(t) of the battery to be detected and the fitting curve of the voltage data set u(t) is less than 0.01, it is determined that the model has converged and the iteration stop condition is met.

In some embodiments, when there is only one fitting parameter, as shown in Figure 3, step S13 may be specifically:

Step S21: Calculate the average value of the fitting parameters according to the fitting parameters of all batteries to be detected in the battery pack;

Step S22: Determine whether the battery to be detected is self-discharged based on the fitting parameters of the battery to be detected and the average value of the fitting parameters.

Among them, the fitting parameters may include open circuit voltage, ohmic internal resistance or electrochemical polarization internal resistance.

In some embodiments, when the fitting parameter is the open circuit voltage, step S21 may specifically include calculating the average open circuit voltage based on the open circuit voltages of all batteries to be detected in the battery pack and the number of batteries to be detected in the battery pack.

Step S22 may specifically include determining the state of charge corresponding to the open circuit voltage of the battery to be detected and the reference state of charge corresponding to the average value of the open circuit voltage according to the open circuit voltage-state of charge relationship table, and determining the state of charge corresponding to the battery to be detected. Whether the difference from the reference state of charge is within the preset range; if so, it is determined that self-discharge has not occurred in the battery to be detected; if not, it is determined that self-discharge has occurred in the battery to be detected. As a specific example, when the state of charge corresponding to the battery to be detected is less than the reference state of charge and the absolute value of the difference between the state of charge and the reference state of charge is greater than 4% of the reference state of charge, it is determined that the battery to be detected has self-discharged .

In some embodiments, when the fitting parameter is ohmic internal resistance, step S21 may specifically include calculating the average ohmic internal resistance based on the ohmic internal resistances of all batteries to be detected in the battery pack and the number of batteries to be detected in the battery pack.

Step S22 may specifically include determining whether the difference between the ohmic internal resistance corresponding to the battery to be detected and the average ohmic internal resistance is less than the first preset threshold; if yes, determining that the battery to be detected has self-discharged; if not, determining that the battery to be detected has not discharged. Self-discharge occurs. The first preset threshold can be set as needed. As a specific example, the first preset threshold can be set to -0.5 milliohms, when the difference between the ohmic internal resistance corresponding to the battery to be detected and the average ohmic internal resistance is less than -0.5 milliohm, it is determined that the battery to be tested has self-discharge.

In some embodiments, when the fitting parameter is the electrochemical polarization internal resistance, step S21 may specifically include calculating the electric power according to the electrochemical polarization internal resistance of all batteries to be detected in the battery group and the number of batteries to be detected in the battery group. Average chemical polarization internal resistance.

Step S22 may be specifically determined to determine whether the difference between the electrochemical polarization internal resistance corresponding to the battery to be detected and the average value of the electrochemical polarization internal resistance is less than a second preset threshold; if yes, it is determined that self-discharge occurs in the battery to be detected; if not , it is determined that the battery to be tested does not self-discharge. The second preset threshold can be set as needed, and it can be the same as or different from the first preset threshold. As a specific example, the second preset threshold can be set to -0.5 milliohms. When the electrochemical response of the battery to be detected is When the difference between the polarization internal resistance and the average electrochemical polarization internal resistance is less than -0.5 milliohms, it is determined that the battery to be tested has self-discharged.

In other embodiments, when there are multiple fitting parameters, as shown in Figure 4, step S13 may be specifically:

Step S31: Determine the average value of the fitting parameters corresponding to each fitting parameter of all batteries to be detected in the battery pack;

Step S32: For each fitting parameter, determine whether the fitting parameters of the battery to be detected and the average value of the corresponding fitting parameters meet the corresponding first preset condition;

and / or,

Step S33: Perform a linear polynomial combination on at least two fitting parameters of each battery to be tested in the battery pack to obtain the characteristic value of each battery to be tested; according to the characteristic value of the battery to be tested and all the batteries to be tested in the battery pack The characteristic value of the battery to be detected is judged whether the characteristic value of the battery to be detected meets the second preset condition;

Step S34: When any one of the first preset condition and the second preset condition is met, it is determined that the battery to be detected has self-discharge; when neither the first preset condition nor the second preset condition is met, it is determined that the battery to be detected is self-discharged. The battery does not self-discharge.

The fitting parameters may include at least two of ohmic internal resistance, electrochemical polarization internal resistance, electrochemical polarization capacitance, concentration polarization internal resistance and concentration polarization capacitance.

In some embodiments, step S31 may specifically include, for each fitting parameter, determining the average value of the fitting parameters based on the fitting parameters of all batteries to be detected in the battery pack and the number of batteries to be detected in the battery pack.

In some embodiments, when the fitting parameter includes the open circuit voltage, step S32 may specifically determine whether the open circuit voltage of the battery to be detected and the corresponding average open circuit voltage satisfy the corresponding first preset condition through the following steps:

According to the open circuit voltage-state of charge relationship table, determine the state of charge corresponding to the open circuit voltage of the battery to be detected and the reference state of charge corresponding to the average value of the open circuit voltage, and determine the state of charge corresponding to the battery to be detected and the reference state of charge Whether the difference is within the preset range;

When the difference between the state of charge corresponding to the open circuit voltage of the battery to be detected and the reference state of charge corresponding to the average value of the open circuit voltage exceeds the preset range, it is determined that the first preset condition is met.

In some embodiments, when the fitting parameter includes ohmic internal resistance, step S32 may specifically determine whether the ohmic internal resistance of the battery to be detected and the corresponding average ohmic internal resistance satisfy the corresponding first preset condition through the following steps:

Determine whether the difference between the ohmic internal resistance corresponding to the battery to be detected and the average ohmic internal resistance is less than the first preset threshold;

When the difference between the ohmic internal resistance corresponding to the battery to be detected and the average ohmic internal resistance is less than the first preset threshold, it is determined that the first preset condition is met.

The first preset threshold can be set as needed.

In some embodiments, when the fitting parameters include electrochemical polarization internal resistance, step S32 may specifically determine whether the electrochemical polarization internal resistance of the battery to be detected and the corresponding electrochemical polarization internal resistance average value satisfy the corresponding requirements through the following steps: The first preset condition:

Determine whether the difference between the electrochemical polarization internal resistance corresponding to the battery to be detected and the average electrochemical polarization internal resistance is less than a second preset threshold;

When the difference between the electrochemical polarization internal resistance corresponding to the battery to be detected and the average electrochemical polarization internal resistance is less than the second preset threshold, it is determined that the first preset condition is met.

The second preset threshold can be set as needed, and it can be the same as or different from the first preset threshold.

In some embodiments, the following expression can be used to perform a linear polynomial combination on the fitting parameters of each battery to be detected in the battery pack to obtain the characteristic value of each battery to be detected:

Among them, S represents the characteristic value, R ₀ represents the ohmic internal resistance, R ₁ represents the electrochemical polarization internal resistance, C ₁ represents the electrochemical polarization capacitance, R ₂ represents the concentration polarization internal resistance, and C ₂ represents the concentration polarization Capacitance, a ₀ , a ₁ , a ₂ , a ₃ , a ₄ , b ₀ , b ₁ , b ₂ , b ₃ and b ₄ are constants.

Among them, at least two of a ₀ , a ₁ , a ₂ , a ₃ and a ₄ are non-zero constants, and at least two of b ₀ , b ₁ , b ₂ , b ₃ and b ₄ are non-zero constants. .

In other embodiments, when the fitting parameters include ohmic internal resistance and at least one polarization internal resistance, and the polarization internal resistance includes electrochemical polarization internal resistance and concentration polarization internal resistance, each step can be obtained through the following steps. Characteristic values of the batteries to be tested:

The ohmic internal resistance and at least one polarization internal resistance of each battery to be detected in the battery pack are respectively summed to obtain the characteristic value of each battery to be detected.

In some embodiments, in step S33, judging whether the characteristic value of the battery to be tested meets the second preset condition based on the characteristic value of the battery to be tested and the characteristic values of all batteries to be tested in the battery pack may include:

According to the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack, determine whether the characteristic value of the battery to be detected is an outlier; if so, determine that the characteristic value of the battery to be detected meets the second preset condition; if No, it is determined that the characteristic value of the battery to be detected does not meet the second preset condition.

In some embodiments, determining whether the characteristic value of the battery to be detected is an outlier is determined based on the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack, including:

Determine the median characteristic value from the characteristic values of all batteries to be tested and calculate the absolute median difference based on the characteristic values of all batteries to be tested;

Determine whether the characteristic value of the battery to be detected is less than the difference between the median characteristic value and the first preset multiple absolute median difference. If so, determine that the characteristic value of the battery to be detected is an outlier; if not, determine that the battery to be detected is an outlier. The eigenvalues of are not outliers.

Among them, the absolute median difference MAD can be calculated by the following expression:

MAD=median(Si-median(S))

Among them, Si represents the characteristic value of the i-th battery to be tested, median(S) represents the median characteristic value, and MAD is the new data obtained by subtracting the median characteristic value from the characteristic value of the i-th battery to be tested. Get the median of the absolute value of the new data from the absolute value.

In other embodiments, determining whether the characteristic value of the battery to be detected is an outlier is determined based on the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack, including:

Calculate the average characteristic value based on the characteristic values of all batteries to be tested, and calculate the standard deviation of the characteristic values based on the characteristic values of the remaining batteries to be tested in the battery pack except the battery to be tested;

Determine whether the characteristic value of the selected battery to be tested is less than the difference between the average characteristic value and the standard deviation of the second preset multiple characteristic value; if so, determine whether the characteristic value of the selected battery to be tested is an outlier; if not, Make sure that the characteristic value of the battery to be tested is not an outlier.

In some embodiments, when it is determined based only on steps S31 and S32 whether the battery to be detected self-discharges, step S34 may specifically be: when any one of the multiple fitting parameters of the battery to be detected satisfies the first predetermined Set conditions to determine that self-discharge occurs in the battery to be detected; when multiple fitting parameters of the battery to be detected do not meet the first preset condition, it is determined that self-discharge does not occur in the battery to be detected.

In other embodiments, when determining whether self-discharge occurs in the battery to be detected based only on step S33, step S34 may specifically include determining that self-discharge occurs in the battery to be detected when the characteristic value of the battery to be detected meets the second preset condition; When the characteristic value of the battery to be detected does not meet the second preset condition, it is determined that self-discharge has not occurred in the battery to be detected.

In other embodiments, when it is simultaneously determined based on steps S31, S32 and S33 whether the battery to be detected self-discharges, as long as any one of the first preset condition and the second preset condition is met, it is determined that the battery to be detected is The battery self-discharges; when neither the first preset condition nor the second preset condition is satisfied, it is determined that the battery to be detected does not self-discharge.

The above is a battery self-discharge detection method provided by an embodiment of the present invention. By connecting multiple batteries to be detected with the same initial state of charge in series to form a battery pack, the total current of the battery pack at different times during the charging process and the end of charging are obtained in real time. The voltage data set of each battery to be detected in the battery pack during the post-rest period; construct a second-order equivalent battery model, using the voltage data set of each battery and the total current of the battery pack at different times as the second-order equivalent battery model As input, the least squares method is used to fit the parameters in the second-order equivalent battery model to obtain at least one fitting parameter for each battery to be tested; according to the fitting parameters corresponding to the battery to be tested in the battery pack and the battery The fitting parameters corresponding to all batteries to be tested in the group determine whether self-discharge occurs in the battery to be tested. This method determines whether self-discharge occurs in the battery to be detected by analyzing and comparing the fitting parameters of a single battery to be detected in the battery pack and the fitting parameters of all batteries to be detected in the battery pack, and avoids the correlation based on the battery to be detected alone. Parameters for self-discharge identification can be applied to problems with limited scope or low identification accuracy, and can effectively detect battery self-discharge.

Another aspect of the present invention also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, it can implement the battery self-discharge detection method in any of the above embodiments. . The computer-readable storage medium may be a storage device formed by various electronic devices. Optionally, in the embodiment of the present invention, the computer-readable storage medium is a non-transitory computer-readable storage medium.

Another aspect of the present invention also provides an electronic device, which includes: a memory and a processor. A computer program is stored in the memory. When the computer program is executed by the processor, the battery self-discharge detection described in any of the above embodiments is implemented. method.

So far, the technical solution of the present invention has been described with reference to the preferred embodiments shown in the drawings. However, those skilled in the art can easily understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to relevant technical features, and technical solutions after these modifications or substitutions will fall within the protection scope of the present invention.

Claims (10)

1. A battery self-discharge detection method, characterized by comprising: The total current of the battery pack at different times during the charging process and the voltage of each battery to be detected in the battery pack at different times during the rest period after charging are obtained in real time, and a voltage data set of each battery to be detected is obtained. The group includes a plurality of batteries to be tested connected in series, and the initial state of charge of each battery to be tested is the same; The voltage data set of each battery to be detected and the total current of the battery pack at different times are input into a second-order equivalent battery model, and the least squares method is used to calculate the second-order equivalent battery model. The parameters are fitted to obtain at least one fitting parameter of each of the batteries to be detected; Whether the battery to be detected self-discharges is determined based on the fitting parameters corresponding to the battery to be detected in the battery pack and the fitting parameters corresponding to all the batteries to be detected in the battery pack. 2. The method according to claim 1, characterized in that when there is only one fitting parameter, the fitting parameter corresponding to the battery to be detected in the battery pack and all the parameters to be detected in the battery pack are The fitting parameters corresponding to the detection battery determine whether self-discharge occurs in the battery to be detected, including: Calculate the average value of the fitting parameters according to the fitting parameters of all batteries to be detected in the battery pack; Whether the battery to be detected self-discharges is determined based on the fitting parameters of the battery to be detected and the average value of the fitting parameters. 3. The method according to claim 2, wherein the fitting parameters include open circuit voltage, ohmic internal resistance or electrochemical polarization internal resistance. According to the fitting parameters of the battery to be detected and the fitting The average parameter value determines whether self-discharge occurs in the battery to be tested, including: When the fitting parameter is the open circuit voltage, determine the state of charge corresponding to the open circuit voltage of the battery to be detected and the reference state of charge corresponding to the average value of the open circuit voltage according to the open circuit voltage-state of charge relationship table, and determine Whether the difference between the state of charge corresponding to the battery to be detected and the reference state of charge is within a preset range; if so, it is determined that the battery to be detected has not self-discharged; if not, it is determined that the battery to be detected is not self-discharged Self-discharge occurs; When the fitting parameter is the ohmic internal resistance, determine whether the difference between the ohmic internal resistance corresponding to the battery to be detected and the average ohmic internal resistance is less than the first preset threshold; if so, determine whether the battery to be detected has occurred. Self-discharge; if not, determine that the battery to be detected does not self-discharge; When the fitting parameter is electrochemical polarization internal resistance, determine whether the difference between the electrochemical polarization internal resistance corresponding to the battery to be detected and the average electrochemical polarization internal resistance is less than the second preset threshold; if If yes, it is determined that self-discharge has occurred in the battery to be detected; if not, it is determined that self-discharge has not occurred in the battery to be detected. 4. The method according to claim 1, characterized in that when there are multiple fitting parameters, the fitting parameter corresponding to the battery to be detected in the battery pack and all the batteries to be detected in the battery pack are The fitting parameters corresponding to the detection battery determine whether self-discharge occurs in the battery to be detected, including: Determine the average value of the fitting parameters corresponding to each fitting parameter of all batteries to be detected in the battery pack; For each fitting parameter, determine whether the fitting parameter of the battery to be detected and the corresponding average value of the fitting parameter meet the corresponding first preset condition; And/or, perform a linear polynomial combination on at least two fitting parameters of each battery to be detected in the battery pack to obtain the characteristic value of each battery to be detected; according to the characteristic value of the battery to be detected and the The characteristic values of all batteries to be detected in the battery pack are determined to determine whether the characteristic values of the batteries to be detected meet the second preset condition; When any one of the first preset condition and the second preset condition is met, it is determined that the battery to be detected has self-discharge; when neither the first preset condition nor the second preset condition is met, it is determined that the battery to be detected has self-discharge. Check that the battery does not self-discharge. 5. The method according to claim 4, characterized in that when the fitting parameter is an open circuit voltage, and the state of charge corresponding to the open circuit voltage of the battery to be detected and the reference charge corresponding to the average value of the open circuit voltage When the difference in electrical status exceeds the preset range, it is determined that the first preset condition is met; When the fitting parameter is ohmic internal resistance, and the difference between the ohmic internal resistance corresponding to the battery to be detected and the average ohmic internal resistance is less than the first preset threshold, it is determined that the first preset condition is met; When the fitting parameter is the electrochemical polarization internal resistance, and the difference between the electrochemical polarization internal resistance corresponding to the battery to be detected and the average electrochemical polarization internal resistance is less than the second preset threshold, it is determined that the the first preset condition. 6. The method according to claim 4, characterized in that the characteristic value of each battery to be detected is obtained by performing a linear polynomial combination on the fitting parameters of each battery to be detected in the battery pack using the following expression: Among them, S represents the characteristic value, R ₀ represents the ohmic internal resistance, R ₁ represents the electrochemical polarization internal resistance, C ₁ represents the electrochemical polarization capacitance, R ₂ represents the concentration polarization internal resistance, and C ₂ represents the concentration polarization Capacitance, a ₀ , a ₁ , a ₂ , a ₃ , a ₄ , b ₀ , b ₁ , b ₂ , b ₃ and b ₄ are constants. 7. The method according to claim 4, wherein the fitting parameters include ohmic internal resistance and at least one polarization internal resistance, and the polarization internal resistance includes electrochemical polarization internal resistance and concentration difference electrode. To reduce the internal resistance, perform a linear polynomial combination on at least two fitting parameters of each battery to be tested in the battery pack to obtain the characteristic value of each battery to be tested, including: The ohmic internal resistance and the at least one polarization internal resistance of each battery to be detected in the battery pack are respectively summed to obtain the characteristic value of each battery to be detected. 8. The method according to claim 6 or 7, characterized in that the characteristics of the battery to be detected are determined based on the characteristic values of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack. Whether the value meets the second preset condition, including: According to the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack, determine whether the characteristic value of the battery to be detected is an outlier; if so, determine the characteristic value of the battery to be detected The second preset condition is met; if not, it is determined that the characteristic value of the battery to be detected does not meet the second preset condition. 9. The method according to claim 8, characterized in that, based on the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack, it is determined whether the characteristic value of the battery to be detected is an ion. Group values include: Determine the median characteristic value from the characteristic values of all batteries to be tested and calculate the absolute median difference based on the characteristic values of all batteries to be tested; Determine whether the characteristic value of the battery to be detected is less than the difference between the median characteristic value and the first preset multiple absolute median difference. If so, determine that the characteristic value of the battery to be detected is an outlier; if not, It is determined that the characteristic value of the battery to be detected is not an outlier. 10. The method according to claim 8, characterized in that, based on the characteristic value of the battery to be detected and the characteristic values of all batteries to be detected in the battery pack, it is determined whether the characteristic value of the battery to be detected is an isolated Group values include: Calculate the average characteristic value based on the characteristic values of all batteries to be detected, and calculate the standard deviation of the characteristic values based on the characteristic values of the remaining batteries to be detected in the battery pack except the battery to be detected selected for detection; Determine whether the characteristic value of the selected battery to be detected is less than the difference between the average characteristic value and the second preset multiple characteristic value standard deviation; if so, determine that the characteristic value of the selected battery to be detected is an outlier. ; If not, determine that the characteristic value of the battery to be detected selected for detection is not an outlier.