Battery DC impedance estimation method and device

Abstract

The invention discloses a battery DC impedance estimation method and device, and a battery management system can determine a first time period and a second time period according to the sampling time and the sampling current in battery operation data, and obtains a first impedance estimation value according to the sampling voltage and the sampling current of the first time period. And obtaining an impedance compensation value according to the sampling voltage, the sampling current and the sampling temperature in the second time period, and further determining a battery DC impedance estimation value according to the first impedance estimation value and the impedance compensation value. The battery management system can estimate the direct current impedance of the battery by adopting an equivalent heat production internal resistance mode according to the sampling time, the sampling voltage, the sampling current and the sampling temperature in the battery operation data. The method has higher precision than an equivalent circuit method to obtain a DC impedance estimation value, and has better mobility than an equivalent circuit method to estimate DC impedance.

Description

[0001] This application is a divisional application of the invention application with the application date of November 10, 2022, the Chinese application number of 202211407306.X, and the invention name of "Battery Direct Current Resistance Estimation Method and Device". TECHNICAL FIELD

[0002] The present application relates to the field of batteries, in particular to a battery direct current resistance estimation method and device. BACKGROUND

[0003] At present, a battery, which can be a lithium battery, is usually arranged in an energy storage system to store excess electricity. The service life of the battery is generally required to reach 20 to 25 years. However, the battery will age after long-term use, and the state of health (SOH) of the aged battery decreases. In order to ensure that the energy storage system can operate safely and stably, the battery direct current resistance (DCR) needs to be estimated, and the aging degree of the battery is estimated based on the battery direct current resistance.

[0004] In the related art, the equivalent circuit method can be used to estimate the battery direct current resistance. However, the accuracy of the battery direct current resistance estimated by this method is low. SUMMARY

[0005] In view of the above problems, the present application provides a battery direct current resistance estimation method and device, which can solve the problem of low accuracy of battery direct current resistance estimation in the related art.

[0006] In a first aspect, a battery direct current resistance estimation method is provided, comprising:

[0007] Obtaining battery operation data, wherein the battery operation data includes a sampling time, a sampling voltage, a sampling current, and a sampling temperature;

[0008] Determining a first time period and a second time period according to the sampling time and the sampling current;

[0009] Obtaining a first impedance estimation value according to the sampling voltage and the sampling current of the first time period, and obtaining an impedance compensation value according to the sampling voltage, the sampling current, and the sampling temperature of the second time period;

[0010] Determining a battery direct current resistance estimation value according to the first impedance estimation value and the impedance compensation value.

[0011] The battery direct current impedance estimation method provided by the embodiments of the present disclosure has higher precision than the direct current impedance estimation values obtained by the definition method and the equivalent circuit method, and has better migration than the method of estimating direct current impedance by the equivalent circuit. The method is suitable for direct current impedance estimation in most working condition scenes in the whole life cycle of the battery, and can solve the problem that direct current impedance estimation values in different working conditions cannot be directly compared.

[0012] In some embodiments, the first time period and the second time period are determined according to the sampling time and the sampling current, comprising:

[0013] The current step starting point is determined according to the sampling time and the sampling current;

[0014] The first time period and the second time period are determined according to the current step starting point.

[0015] In some embodiments, the current step starting point is determined according to the sampling time and the sampling current, comprising:

[0016] According to the sampling time and the sampling current, the previous sampling time when the sampling current change value of the adjacent two sampling times is greater than the preset current threshold value is taken as the current step starting point, so as to determine the current step starting point.

[0017] In some embodiments, the preset current threshold value is determined according to the minimum current causing the change of the external polarization of the battery cell. In this way, the accuracy of the determined current step starting point is improved.

[0018] In some embodiments, the first time period is a time period after the current step starting point, and the second time period is a time period before the current step starting point, so as to ensure the reliability of the determined first time period and the second time period.

[0019] In some embodiments, the first impedance estimation value is obtained according to the sampling voltage and the sampling current of the first time period, comprising:

[0020] The product of the sampling voltage and the sampling current of the first time period is accumulated to obtain a first estimation value, and the square of the sampling current of the first time period is accumulated to obtain a second estimation value; the first impedance estimation value is determined according to the first estimation value and the second estimation value, so as to ensure the reliability of the determined first impedance estimation value.

[0021] In some embodiments, the first impedance estimation value is calculated according to the following formula:

[0022]

[0023] Wherein, DCRO is the first impedance estimation value, U i is the difference between the sampling voltage of the i th sampling time of the first time period and the sampling voltage of the current step starting point, I iis the sampling current at the i-th sampling time of the first time period, i is an integer greater than or equal to 0 and less than or equal to t. The first impedance estimation value determined by the formula has high accuracy.

[0024] In some embodiments, the impedance compensation value is obtained according to the sampling voltage, the sampling current and the sampling temperature of the second time period, comprising:

[0025] The sampling voltage, the sampling current and the sampling temperature of the second time period and the second time period are input into the impedance estimation model to obtain the impedance compensation value.

[0026] The impedance estimation model can improve the efficiency and accuracy of determining the impedance compensation value.

[0027] In some embodiments, after obtaining the battery operation data, the method further comprises:

[0028] The battery operation data is preprocessed, wherein the preprocessing operation comprises one or more of the empty processing operation, the de-duplication processing operation, the exception filtering operation and the time sorting operation.

[0029] By preprocessing the battery operation data, the quality of the data used to estimate the battery DC impedance is ensured, thereby improving the accuracy of determining the battery DC impedance estimation value.

[0030] In some embodiments, after determining the battery DC impedance estimation value, the method further comprises:

[0031] According to the battery DC impedance estimation value, one or more of the battery cell aging state, the battery cell real-time power, the battery cell heat generation and the battery cell consistency are determined.

[0032] By determining the battery cell aging state, the aging trajectory of the cell can be accurately reflected, and the aging direction of the cell can be accurately predicted. Moreover, the real-time power capability of the cell can be accurately estimated according to the battery DC impedance estimation value, the battery cell heat generation can be accurately evaluated, and the battery cell consistency can be accurately evaluated.

[0033] In a second aspect, a computer readable storage medium is provided, and the computer readable storage medium stores a computer program. When the computer program is executed by a computer device, the computer device implements the battery DC impedance estimation method according to the above-mentioned aspect.

[0034] In a third aspect, a battery management system is provided, comprising a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, the battery management system implements the battery DC impedance estimation method according to the above-mentioned aspect.

[0035] In a fourth aspect, a cloud server is provided, comprising a memory and a processor, the memory storing a computer program, the computer program being executed by the processor to enable the cloud server to implement the battery direct current impedance estimation method according to the above aspect.

[0036] In a fifth aspect, a battery direct current impedance estimation device is provided, comprising:

[0037] An acquisition module is configured to acquire battery operation data, wherein the battery operation data comprises a sampling time, a sampling voltage, a sampling current and a sampling temperature.

[0038] A determination module is configured to determine a current step starting point according to the sampling time and the sampling current, and determine a first time period and a second time period according to the current step starting point.

[0039] An estimation module is configured to obtain a first impedance estimation value according to the sampling voltage and the sampling current of the first time period, obtain an impedance compensation value according to the sampling voltage, the sampling current and the sampling temperature of the second time period, and determine a battery direct current impedance estimation value according to the first impedance estimation value and the impedance compensation value.

[0040] Additional aspects and advantages of the present disclosure will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a flowchart of a battery direct current impedance estimation method provided by an embodiment of the present disclosure;

[0042] Figure 2 is a flowchart of another battery direct current impedance estimation method provided by an embodiment of the present disclosure;

[0043] Figure 3 is a block diagram of a battery direct current impedance estimation method provided by an embodiment of the present disclosure;

[0044] Figure 4 is a block diagram of another battery direct current impedance estimation method provided by an embodiment of the present disclosure;

[0045] Figure 5 is a structural schematic diagram of a battery management system provided by an embodiment of the present disclosure;

[0046] Figure 6 is a structural schematic diagram of a cloud server provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0047] Embodiments of the present disclosure are described below in detail, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present disclosure, and cannot be understood as a limitation of the present disclosure.

[0048] At present, a battery, which can be a lithium battery, is usually required to be arranged in an energy storage system to store excess electricity. The service life of the battery is generally required to reach 20 to 25 years. However, the battery will age after long-term use, and the health state of the aged battery will decrease. In order to ensure that the energy storage system can operate safely and stably, it is necessary to estimate the direct current impedance of the battery and determine the aging degree of the battery based on the direct current impedance of the battery.

[0049] In the related art, the direct current impedance of the battery is estimated by using an equivalent circuit method or a definition method. The direct current impedance of the battery estimated by using the definition method is The ΔU is the change amount of the voltage, and the ΔI is the change amount of the discharge current.

[0050] However, if the equivalent circuit method is used to estimate the direct current impedance of the battery, the precision of the direct current impedance of the battery estimated by this estimation method is low, and the migration is poor. If the definition method is used to estimate the direct current impedance of the battery, it is required that the battery is at rest for a long time before the current step, the step current is required to be large enough, the step current is required to last for a certain period of time and cannot be switched in the middle, the data is required to have no update delay, and the voltage and current data are required to have good synchronization. It can be seen that this estimation method has high requirements for the quality of the data, the calculation conditions are strict, and the available working condition data is less. In addition, since the direct current impedance of the battery is related to the temperature, the state of charge and the size of the step current, the direct current impedances calculated under different working conditions are greatly different and cannot be directly compared.

[0051] The embodiment of the present disclosure provides a battery direct current impedance estimation method. In the method, the battery management system can estimate the direct current impedance of the battery by using an equivalent heat generation resistance method according to the sampling time, the sampling voltage, the sampling current and the sampling temperature in the battery operation data. The method has higher precision than the direct current impedance estimation values obtained by the definition method and the equivalent circuit method. Compared with the method of estimating the direct current impedance by using the equivalent circuit, the method has better migration, is suitable for direct current impedance estimation in most working condition scenes in the whole life cycle of the battery, and can solve the problem that the direct current impedance estimation values under different working conditions cannot be directly compared.

[0052] Figure 1 is a flowchart of a battery direct current impedance estimation method provided by the embodiment of the present disclosure, which is applied to a battery management system or a cloud server. In the following, the method applied to the battery management system is taken as an example for description. As shown in FIG. 1, the method comprises the following steps. Figure 1 The method comprises the following steps:

[0053] Step 101, obtaining battery operation data.

[0054] The battery management system can pre-store the battery operation data. After receiving the battery DC impedance estimation instruction, the battery management system can obtain the pre-stored battery operation data. The battery management system can generate the battery DC impedance estimation instruction after receiving the DC impedance estimation operation for the battery, or the battery DC impedance estimation instruction can also be generated periodically. The battery operation data can include the sampling time, the sampling voltage, the sampling current, and the sampling temperature.

[0055] Step 102, determining the first time period and the second time period according to the sampling time and the sampling current.

[0056] After obtaining the battery operation data, the battery management system can determine the first time period and the second time period according to the sampling time and the sampling current.

[0057] Step 103, obtaining the first impedance estimation value according to the sampling voltage and the sampling current of the first time period, and obtaining the impedance compensation value according to the sampling voltage, the sampling current, and the sampling temperature of the second time period.

[0058] After obtaining the battery operation data, the battery management system can also obtain the first impedance estimation value according to the sampling voltage and the sampling current of the first time period, and obtain the impedance compensation value according to the sampling voltage, the sampling current, and the sampling temperature of the second time period.

[0059] Step 104, determining the battery DC impedance estimation value according to the first impedance estimation value and the impedance compensation value.

[0060] After determining the first impedance estimation value and the impedance compensation value, the battery management system can determine the battery DC impedance estimation value according to the first impedance estimation value and the impedance compensation value. Optionally, the battery management system can determine the sum of the first impedance estimation value and the impedance compensation value as the battery DC impedance estimation value.

[0061] In summary, the battery DC impedance estimation method provided by the embodiments of the present disclosure can determine the first time period and the second time period according to the sampling time and the sampling current in the battery operation data, obtain the first impedance estimation value according to the sampling voltage and the sampling current of the first time period, obtain the impedance compensation value according to the sampling voltage, the sampling current, and the sampling temperature of the second time period, and then determine the battery DC impedance estimation value according to the first impedance estimation value and the impedance compensation value.

[0062] That is, the battery management system can estimate the battery DC impedance according to the sampling time, the sampling voltage, the sampling current, and the sampling temperature in the battery operation data by using the equivalent heat generation resistance method, and the method has higher precision than the estimated DC impedance values obtained by the definition method and the equivalent circuit method. Compared with the equivalent circuit method for estimating the DC impedance, the method has better portability, is suitable for DC impedance estimation in most working condition scenes in the whole life cycle of the battery, and can solve the problem that the estimated DC impedance values in different working conditions cannot be directly compared.

[0063] Figure 2 is a flowchart of another battery DC impedance estimation method provided by the embodiments of the present disclosure, which is applied to a battery management system or a cloud server. The following takes the method applied to the battery management system as an example for description. As shown in Figure 2 the method can include:

[0064] Step 201, obtaining battery operation data.

[0065] In the embodiments of the present disclosure, the battery management system can pre-store the battery operation data. After receiving a battery DC impedance estimation instruction, the battery management system can obtain the pre-stored battery operation data. Optionally, the battery management system can generate the battery DC impedance estimation instruction after receiving a DC impedance estimation operation for the battery, or the battery management system can also periodically generate the battery DC impedance estimation instruction.

[0066] The battery operation data can include a sampling time, a sampling voltage, a sampling current, and a sampling temperature. The sampling time refers to the time when the sampling voltage, the sampling current, and the sampling temperature of the battery are sampled. The sampling voltage refers to the voltage of the battery at a sampling time, the sampling current refers to the current of the battery at a sampling time, and the sampling temperature refers to the temperature of the battery at a sampling time. The battery operation data can include multiple sampling times, and the sampling voltage, the sampling current, and the sampling temperature at each sampling time in the multiple sampling times.

[0067] Step 202, performing a preprocessing operation on the battery operation data.

[0068] After obtaining the battery operation data, the battery management system can also perform a preprocessing operation on the battery operation data. The preprocessing operation can include one or more of a null processing operation, a duplicate processing operation, an exception filtering operation, and a time sorting operation.

[0069] If the preprocessing operation comprises a null processing operation, for each sampling time point, the battery management system can detect whether the sampling voltage, the sampling battery and the sampling temperature at the sampling time point are null, respectively. If any of the sampling voltage, the sampling battery and the sampling temperature at the sampling time point is null, the sampling time point and the sampling voltage, the sampling battery and the sampling temperature at the sampling time point can be removed. If none of the sampling voltage, the sampling battery and the sampling temperature at the sampling time point is null, the sampling time point and the sampling voltage, the sampling battery and the sampling temperature at the sampling time point can be retained.

[0070] If the preprocessing operation comprises a null processing operation, for each sampling time point, the battery management system can detect whether the sampling voltage, the sampling battery and the sampling temperature at the sampling time point are null, respectively. If any of the sampling voltage, the sampling battery and the sampling temperature at the sampling time point is null, the sampling time point and the sampling voltage, the sampling battery and the sampling temperature at the sampling time point can be removed. If none of the sampling voltage, the sampling battery and the sampling temperature at the sampling time point is null, the sampling time point and the sampling voltage, the sampling battery and the sampling temperature at the sampling time point can be retained.

[0071] If the preprocessing operation comprises an abnormal value filtering operation, for each sampling time point, the battery management system can detect whether the sampling voltage, the sampling battery and the sampling temperature at the sampling time point are abnormal values. If any of the sampling voltage, the sampling battery and the sampling temperature at the sampling time point is an abnormal value, the sampling time point and the sampling voltage, the sampling battery and the sampling temperature at the sampling time point can be removed. If none of the sampling voltage, the sampling battery and the sampling temperature at the sampling time point is an abnormal value, the sampling time point and the sampling voltage, the sampling battery and the sampling temperature at the sampling time point can be retained.

[0072] The current threshold range, the temperature threshold range and the voltage threshold range can be determined according to empirical values or according to rated parameters of the battery.

[0073] For each sampling current, if the battery management system detects that the sampling current is within the current threshold range, the battery management system can determine that the sampling current is not an abnormal value. If the battery management system detects that the sampling current is outside the current threshold range, the battery management system can determine that the sampling current is an abnormal value.

[0074] For each sampling voltage, if the battery management system detects that the sampling voltage is within the voltage threshold range, the battery management system can determine that the sampling voltage is not an abnormal value. If the battery management system detects that the sampling voltage is outside the voltage threshold range, the battery management system can determine that the sampling voltage is an abnormal value.

[0075] For each sampling temperature, the battery management system can determine that the sampling temperature is not an abnormal value if the battery management system detects that the sampling temperature is within the temperature threshold range. The battery management system can determine that the sampling temperature is an abnormal value if the battery management system detects that the sampling temperature is outside the temperature threshold range.

[0076] If the preprocessing operation includes a time sorting operation, the battery management system can further perform the time sorting operation on the plurality of sampling time instants to sort the sampling voltages, the sampling currents, and the sampling temperatures of the plurality of sampling time instants. Optionally, the time sorting operation can be an ascending operation or a descending operation. Embodiments of the present disclosure take the ascending operation as an example for illustration.

[0077] By performing the preprocessing operation on the battery operating data, the quality of the data used for estimating the DC impedance of the battery is ensured, thereby improving the accuracy of the determination of the DC impedance estimation value of the battery.

[0078] In step 203, according to the sampling time instants and the sampling currents, a previous sampling time instant of adjacent two sampling time instants is determined as a current step starting point, if a sampling current change value of the adjacent two sampling time instants is greater than a preset current threshold.

[0079] After performing the preprocessing operation on the battery operating data, the battery management system can further determine a current step starting point according to the sampling time instants and the sampling currents.

[0080] Optionally, the battery management system can determine a current step starting point according to the sampling time instants and the sampling currents, if a sampling current change value of adjacent two sampling time instants is greater than a preset current threshold. The preset current threshold can be determined according to the minimum current that causes the change of the external polarization of the battery cell.

[0081] Optionally, for the plurality of sampling time instants, the battery management system can determine a sampling current change value of any adjacent two sampling time instants in the plurality of sampling time instants. If the sampling current change value of the adjacent two sampling time instants is greater than a preset current threshold, the previous sampling time instant of the adjacent two sampling time instants can be determined as a current step starting point. If the sampling current change value of the adjacent two sampling time instants is not greater than the preset current threshold, the previous sampling time instant of the adjacent two sampling time instants does not need to be determined as a current step starting point.

[0082] In step 204, a first time period and a second time period are determined according to the current step starting point.

[0083] After determining the current step start point, the battery management system can determine a first time period and a second time period according to the current step start point. The first time period can be a time period after the current step start point, and the first time period can be a time period of a first time length taken backward from the current step start point. The first time period t1 can satisfy t1=t0+Δt1, where t0 is the current step start point, and Δt1 is the first time length. The second time period can be a time period before the current step start point, and the second time period can be a time period of a second time length taken forward from the current step start point. The second time period t2 can satisfy t2=t0-Δt2, where Δt2 is the second time length.

[0084] In the embodiments of the present disclosure, the first time length and the second time length can be the shortest time length that can cause a temperature change of the battery cell under the action of a certain current, thereby ensuring the accuracy of the determination of the first time length and the second time length.

[0085] In step 205, the product of the sampled voltage and the sampled current of the first time period is accumulated to obtain a first estimated value, and the square of the sampled current of the first time period is accumulated to obtain a second estimated value.

[0086] After determining the first time period and the second time period, the battery management system can accumulate the product of the sampled voltage and the sampled current of the first time period to obtain a first estimated value, and can accumulate the square of the sampled current of the first time period to obtain a second estimated value.

[0087] Optionally, the first estimated value can satisfy: The second estimated value can satisfy: The U i The difference between the sampled voltage of the i th sampling time point of the first time period and the sampled voltage of the current step start point, the i i The sampled current of the i th sampling time point of the first time period, the t is an integer less than the total number of sampling time points in the first time period, the i is an integer greater than or equal to 0 and less than or equal to t.

[0088] In step 206, a first impedance estimated value is determined according to the first estimated value and the second estimated value.

[0089] After obtaining the first estimated value and the second estimated value, the battery management system can determine a first impedance estimated value according to the first estimated value and the second estimated value, where the first impedance estimated value is calculated according to the following formula:

[0090] The DCRO can be the first impedance estimated value.

[0091] In step 207, a preconfigured impedance estimation model is determined.

[0092] The battery management system can further determine a pre-configured impedance estimation model after determining the first impedance estimation value, wherein the impedance estimation model can be pre-stored in the battery management system, and the impedance estimation model can be trained by using a plurality of sample data, and each sample data can include a sample time period, a sample sampling voltage of the sample time period, a sample sampling current, a sample sampling temperature, and a sample impedance compensation value.

[0093] In step 208, the sampling voltage, the sampling current, and the sampling temperature of the second time period and the second time period are input into the impedance estimation model to obtain the impedance compensation value.

[0094] The battery management system can input the sampling voltage, the sampling current, and the sampling temperature of the second time period and the second time period into the pre-configured impedance estimation model after determining the pre-configured impedance estimation model, and the value output by the impedance estimation model is the impedance compensation value, thereby obtaining the impedance compensation value. Using the impedance estimation model can improve the efficiency and accuracy of determining the impedance compensation value.

[0095] In step 209, the battery direct current impedance estimation value is determined according to the first impedance estimation value and the impedance compensation value.

[0096] The battery management system can determine the battery direct current impedance estimation value according to the first impedance estimation value and the impedance compensation value after obtaining the first impedance estimation value and the impedance compensation value. Optionally, the battery management system can determine the sum of the first impedance estimation value and the impedance compensation value as the battery direct current impedance estimation value, that is, the battery direct current impedance estimation value can satisfy: DCRO+DCRO sup , the DCRO sup is the impedance compensation value.

[0097] In step 210, one or more of the battery cell aging state, the battery cell real-time power, the battery cell heat generation, and the battery cell consistency are determined according to the battery direct current impedance estimation value.

[0098] The battery management system can further determine one or more of the battery cell aging state, the battery cell real-time power, the battery cell heat generation, and the battery cell consistency according to the battery direct current impedance estimation value after determining the battery direct current impedance estimation value. The battery cell real-time power can refer to the real-time power state (SOP) of the battery cell. By determining the battery cell aging state, the aging trajectory of the cell can be accurately reflected, and the aging direction of the cell can be accurately predicted. The real-time power capability of the cell can be accurately estimated according to the battery direct current impedance estimation value, the battery cell heat generation can be accurately evaluated, and the battery cell consistency can be accurately evaluated.

[0099] The battery management system can also send the battery DC impedance estimation value to a scheduling unit, which can determine one or more of a battery cell aging state, a battery cell real-time power, a battery cell heat production, and a battery cell consistency based on the battery DC impedance estimation value. The scheduling unit can also send the battery DC impedance to other devices that need the battery DC impedance.

[0100] In summary, the embodiments of the present disclosure provide a battery DC impedance estimation method. In the method, the battery management system can determine a current step starting point based on a sampling time and a sampling current in battery operation data, determine a first time period and a second time period based on the current step starting point, obtain a first impedance estimation value based on a sampling voltage and a sampling current in the first time period, obtain an impedance compensation value based on a sampling voltage, a sampling current, and a sampling temperature in the second time period, and then determine a battery DC impedance estimation value based on the first impedance estimation value and the impedance compensation value.

[0101] The method provided by the embodiments of the present disclosure has higher accuracy than the DC impedance estimation values obtained by the definition method and the equivalent circuit method, has better portability than the method of estimating the DC impedance by the equivalent circuit, and does not need to be modeled for different cells. In addition, the method has low requirements for the quality of model input data and is not sensitive to the polarization state before static and the step current, and thus is suitable for DC impedance estimation in most working condition scenarios in the whole life cycle of the cell and can solve the problem that the DC impedance estimation values in different working conditions cannot be directly compared.

[0102] Figure 3 is a block diagram of a battery DC impedance estimation device provided by the embodiments of the present disclosure. The device can be applied in a battery management system or a cloud server, as shown in Figure 3 The device can include:

[0103] The acquisition module 301 is configured to acquire battery operation data.

[0104] The battery operation data includes a sampling time, a sampling voltage, a sampling current, and a sampling temperature.

[0105] The determination module 302 is configured to determine a first time period and a second time period based on the sampling time and the sampling current.

[0106] The estimation module 303 is configured to obtain a first impedance estimation value based on a sampling voltage and a sampling current in the first time period, obtain an impedance compensation value based on a sampling voltage, a sampling current, and a sampling temperature in the second time period, and determine a battery DC impedance estimation value based on the first impedance estimation value and the impedance compensation value.

[0107] In summary, the battery DC impedance estimation device provided by the embodiments of the present disclosure can determine the first time period and the second time period according to the sampling time and the sampling current in the battery operation data, obtain the first impedance estimation value according to the sampling voltage and the sampling current in the first time period, obtain the impedance compensation value according to the sampling voltage, the sampling current and the sampling temperature in the second time period, and then determine the battery DC impedance estimation value according to the first impedance estimation value and the impedance compensation value. That is, the battery management system can estimate the battery DC impedance in an equivalent heat generation resistance manner according to the sampling time, the sampling voltage, the sampling current and the sampling temperature in the battery operation data. The method has higher precision than the DC impedance estimation values obtained by the definition method and the equivalent circuit method, has better transferability than the method of estimating the DC impedance by the equivalent circuit, is suitable for DC impedance estimation in most working condition scenes in the whole life cycle of the battery, and can solve the problem that the DC impedance estimation values in different working conditions cannot be directly compared.

[0108] Optionally, the determining module 302 is configured to:

[0109] determine the current step start point according to the sampling time and the sampling current.

[0110] determine the first time period and the second time period according to the current step start point.

[0111] Optionally, the determining module 302 is configured to:

[0112] determine the previous sampling time, at which the sampling current change value of the adjacent two sampling times is greater than a preset current threshold value, as the current step start point according to the sampling time and the sampling current.

[0113] Optionally, the preset current threshold value is determined according to the minimum current causing the external polarization change of the battery cell.

[0114] Optionally, the first time period is a time period after the current step start point, and the second time period is a time period before the current step start point.

[0115] Optionally, the estimating module 303 is configured to:

[0116] accumulate the product of the sampling voltage and the sampling current in the first time period to obtain a first estimation value, and accumulate the square of the sampling current in the first time period to obtain a second estimation value.

[0117] determine the first impedance estimation value according to the first estimation value and the second estimation value.

[0118] Optionally, the first impedance estimation value is calculated according to the following formula:

[0119]

[0120] wherein, DCRO is the first impedance estimation value, U i is a difference between the sampling voltage at the i-th sampling moment of the first time period and the sampling voltage at the step start point of the current, I i is the sampling current at the i-th sampling moment of the first time period, i is an integer greater than or equal to 0 and less than or equal to t.

[0121] Optionally, the estimation module 303 is configured to:

[0122] input the sampling voltage, the sampling current and the sampling temperature of the second time period and the second time period into an impedance estimation model to obtain the impedance compensation value.

[0123] Referring to Figure 3 The device can further include a processing module 304 configured to:

[0124] After obtaining the battery operation data, the battery operation data is preprocessed, wherein the preprocessing operation includes one or more of the empty processing operation, the de-duplication processing operation, the exception filtering operation and the time sorting operation.

[0125] The determination module 302 is further configured to:

[0126] After determining the battery direct current impedance estimation value, one or more of the battery cell aging state, the battery cell real-time power, the battery cell heat generation and the battery cell consistency are determined according to the battery direct current impedance estimation value.

[0127] In summary, the embodiments of the present disclosure provide a battery direct current impedance estimation device, in which the battery management system can determine the first time period and the second time period according to the sampling moment and the sampling current in the battery operation data, obtain the first impedance estimation value according to the sampling voltage and the sampling current of the first time period, and obtain the impedance compensation value according to the sampling voltage, the sampling current and the sampling temperature of the second time period, and then determine the battery direct current impedance estimation value according to the first impedance estimation value and the impedance compensation value. That is, the battery management system can estimate the battery direct current impedance in an equivalent heat generation resistance manner according to the sampling time, the sampling voltage, the sampling current and the sampling temperature in the battery operation data. This method has higher precision than the direct current impedance estimation value obtained by the definition method and the equivalent circuit method, has better transferability than the method of estimating the direct current impedance by the equivalent circuit, is suitable for direct current impedance estimation in most working condition scenes in the whole life cycle of the battery, and can solve the problem that the direct current impedance estimation values in different working conditions cannot be directly compared.

[0128] The embodiments of the present disclosure provide a computer readable storage medium, and the computer readable storage medium stores a computer program. When the computer program is executed by a computer device, the computer device implements the battery direct current impedance estimation method described in the above embodiments.

[0129] Figure 5 is a structural schematic diagram of a battery management system provided by an embodiment of the present disclosure, comprising a memory 501 and a processor 502, the memory 502 stores a computer program, and the computer program is executed by the processor 502, so that the battery management system 50 realizes the battery direct current impedance estimation method described in the above embodiments.

[0130] Figure 6 is a structural schematic diagram of a cloud server provided by an embodiment of the present disclosure, comprising a memory 601 and a processor 602, the memory 601 stores a computer program, and the computer program is executed by the processor 602, so that the cloud server 60 realizes the battery direct current impedance estimation method according to the above embodiments.

[0131] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a list of executable instructions for implementing logic functions, which can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus or device, such as a computer-based system, a system including a processor or other system that can fetch instructions from an instruction execution system, apparatus or device and execute the instructions, or in conjunction with these instruction execution systems, apparatus or devices. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transport programs for use by or in conjunction with an instruction execution system, apparatus or device, or in conjunction with these instruction execution systems, apparatus or devices. More specific examples (non-exhaustive list) of computer-readable medium include the following: electrical connections having one or more wires (electronic devices), portable computer disk boxes (magnetic devices), random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memories), fiber optic devices, and portable compact disc read-only memories (CDROMs). In addition, the computer-readable medium can even be paper or other suitable medium on which the program can be printed, because the program can be electronically obtained, for example, by optical scanning of the paper or other medium, followed by editing, interpretation or necessary processing, if any, in other suitable manner, and then stored in the computer memory.

[0132] It should be understood that various parts of the present disclosure can be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, a plurality of steps or methods can be implemented with software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, and as in another embodiment, it can be implemented with any one or a combination of the following technologies known in the art: discrete logic circuitry having logic gates for implementing logic functions on data signals, application specific integrated circuits (ASICs) having appropriate combinational logic gates, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0133] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0134] In addition, the terms "first", "second", and the like used in the embodiments of the present disclosure are only for the purpose of description and can not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated in the embodiments. Therefore, the features defined with "first", "second", and the like in the embodiments of the present disclosure can explicitly or implicitly indicate that at least one of the features is included in the embodiments. In the description of the present disclosure, the meaning of the word "a plurality of" is at least two or two or more, such as two, three, four, etc., unless otherwise specifically limited in the embodiments.

[0135] In the present disclosure, unless otherwise specifically related or limited in the embodiments, the terms "mounting", "connecting", "connecting" and "fixing" and the like appearing in the embodiments should be understood broadly, for example, the connection can be fixed connection, or detachable connection, or integral, which can be understood, or mechanical connection, electrical connection, etc. Of course, it can also be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements, or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific implementation situation.

[0136] Although the embodiments of the present disclosure have been shown and described above, it can be understood that the above-described embodiments are exemplary and cannot be understood as limiting the present disclosure, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present disclosure.

Claims

1. A method for estimating a battery DC impedance, characterized in that: include: Acquiring battery operation data, wherein the battery operation data includes sampling time, sampling voltage, sampling current and sampling temperature; Determine a current step starting point according to the sampling moment and the sampled current, and determine a first time period and a second time period according to the current step starting point; Obtaining a first impedance estimation value according to the sampled voltage and the sampled current during the first period, and obtaining an impedance compensation value according to the sampled voltage, the sampled current, and the sampled temperature during the second period; A battery DC impedance estimation value is determined according to the first impedance estimation value and the impedance compensation value.

2. The battery DC impedance estimation method according to claim 1, wherein: Determining a current step starting point according to the sampling moment and the sampled current includes: According to the sampling moment and the sampling current, the previous sampling moment at which the sampling current change value between two adjacent sampling moments is greater than a preset current threshold is used as the current step starting point.

3. The battery DC impedance estimation method according to claim 2, characterized in that: The preset current threshold is determined according to a minimum current that causes a change in external polarization of the battery cell.

4. The battery DC impedance estimation method according to claim 1, wherein: The first time period is a time period after the starting point of the current step, and the second time period is a time period before the starting point of the current step.

5. The battery DC impedance estimation method according to claim 1, wherein: Obtaining a first impedance estimation value according to the sampled voltage and the sampled current during the first time period includes: Accumulating the product of the sampled voltage and the sampled current during the first period to obtain a first estimated value, and accumulating the square of the sampled current during the first period to obtain a second estimated value; The first impedance estimate is determined based on the first estimate and the second estimate.

6. The battery DC impedance estimation method according to claim 5, characterized in that: The first impedance estimate is calculated according to the following formula: Wherein, DCRO is the first impedance estimation value, U i is the difference between the sampling voltage at the i-th sampling moment of the first period and the sampling voltage at the starting point of the current step, I i is the sampling current at the i-th sampling moment of the first time period, where i is an integer greater than or equal to 0 and less than or equal to t.

7. The battery DC impedance estimation method according to any one of claims 1 to 6, characterized in that: Obtaining an impedance compensation value according to the sampled voltage, the sampled current, and the sampled temperature during the second period, including: The sampled voltage, sampled current and sampled temperature of the second time period and the second time period are input into an impedance estimation model to obtain the impedance compensation value.

8. The battery DC impedance estimation method according to any one of claims 1 to 6, characterized in that: After obtaining the battery operation data, the method further includes: A preprocessing operation is performed on the battery operation data, wherein the preprocessing operation includes one or more of a null removal operation, a duplicate removal operation, an abnormality filtering operation, and a time sorting operation.

9. The battery DC impedance estimation method according to any one of claims 1 to 6, characterized in that: After determining the estimated battery DC impedance, the method further includes: One or more of a battery cell aging state, a battery cell real-time power, a battery cell heat generation, and a battery cell consistency is determined according to the battery DC impedance estimation value.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a computer device, the computer device implements the battery DC impedance estimation method according to any one of claims 1 to 9.

11. A battery management system, characterized in that: The battery management system comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the battery management system implements the battery DC impedance estimation method according to any one of claims 1 to 9.

12. A cloud server, characterized in that: The cloud server comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the cloud server implements the battery DC impedance estimation method according to any one of claims 1 to 9.

13. A battery DC impedance estimation device, characterized in that: include: An acquisition module is used to acquire battery operation data, wherein the battery operation data includes sampling time, sampling voltage, sampling current and sampling temperature; a determination module, configured to determine a current step starting point according to the sampling moment and the sampled current, and determine a first time period and a second time period according to the current step starting point; an estimation module, configured to obtain a first impedance estimation value based on the sampled voltage and sampled current during the first time period, obtain an impedance compensation value based on the sampled voltage, sampled current, and sampled temperature during the second time period, and determine a battery DC impedance estimation value based on the first impedance estimation value and the impedance compensation value.

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