Battery internal resistance consistency evaluation method and device, vehicle and storage medium

Abstract

The invention relates to a battery internal resistance consistency evaluation method and device, a vehicle and a storage medium. Comprising the following steps: acquiring a first voltage of each cell before discharging, a second voltage of each cell after discharging, a discharging current of a battery system, a third voltage of each cell before charging, a fourth voltage of each cell after charging and a charging current of the battery system in a target charge state, calculating the discharge internal resistance of each battery cell according to the first voltage, the second voltage and the discharge current, recording the maximum discharge internal resistance and the minimum discharge internal resistance, and further calculating the discharge internal resistance extreme value difference of each battery cell; calculating the charging internal resistance of each battery cell according to the third voltage, the fourth voltage and the charging current, recording the maximum charging internal resistance and the minimum charging internal resistance, further calculating the charging internal resistance extreme value difference of each battery cell, and when the discharging internal resistance extreme value difference is smaller than or equal to a discharging internal resistance target value and the charging internal resistance extreme value difference is smaller than or equal to a charging internal resistance target value, determining that the charging internal resistance value is smaller than or equal to the charging internal resistance target value. And judging that the battery system meets the internal resistance consistency evaluation.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and in particular to a method, device, vehicle, and storage medium for evaluating battery internal resistance consistency. Background Art

[0002] With the rapid development of electric vehicles and energy storage systems, the requirements for battery system performance are becoming increasingly stringent, especially in terms of safety, stability, and lifespan. The internal resistance differences between individual cells in a battery system can affect the performance of the entire system, making it crucial to accurately assess the internal resistance consistency of the cells within the battery system.

[0003] In related technologies, the internal resistance consistency of battery cells is usually measured and constrained when the cells are offline, but there is a lack of process management between the cells being offline and the system being grouped, and it is impossible to capture the internal resistance changes under dynamic working conditions. At the same time, there is a lack of quantitative standards for judging the consistency of internal resistance, and a fixed threshold method is usually used, which is difficult to adapt to different battery systems, making it impossible to accurately monitor the battery health status for different battery systems. This problem urgently needs to be solved. Summary of the Invention

[0004] The present application provides a method, device, vehicle and storage medium for evaluating the consistency of battery internal resistance to address the problems that related technologies are unable to capture changes in internal resistance under dynamic working conditions, lack quantitative standards for judging internal resistance consistency, are difficult to adapt to different battery systems, and thus cannot accurately monitor the battery health status for different battery systems.

[0005] A first embodiment of the present application provides a method for evaluating battery internal resistance consistency, comprising the following steps:

[0006] Obtaining a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, a discharge current of the battery system, a third voltage of each battery cell before charge, a fourth voltage of each battery cell after charge, and a charge current of the battery system in a battery system at a target state of charge;

[0007] Calculating the discharge internal resistance of each battery cell according to the first voltage of each battery cell before discharge, the second voltage of each battery cell after discharge, and the discharge current, and recording the maximum discharge internal resistance and the minimum discharge internal resistance of all battery cells to calculate the discharge internal resistance extreme value difference of each battery cell according to the maximum discharge internal resistance and the minimum discharge internal resistance;

[0008] Calculating the charging internal resistance of each battery cell according to the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging, and the charging current, and recording the maximum charging internal resistance and the minimum charging internal resistance of all battery cells, so as to calculate the charging internal resistance extreme value difference of each battery cell according to the maximum charging internal resistance and the minimum charging internal resistance;

[0009] Determine the discharge internal resistance target value of each battery cell and the charging internal resistance target value of each battery cell. If the discharge internal resistance extreme value difference is less than or equal to the discharge internal resistance target value, and the charging internal resistance extreme value difference is less than or equal to the charging internal resistance target value, then determine that the battery system meets the internal resistance consistency assessment.

[0010] According to one embodiment of the present application, obtaining a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, and a discharge current of the battery system in a battery system at a target state of charge includes:

[0011] Based on the target ambient temperature, each of the battery cells is discharged at a first preset rate for a first time at a constant current, until the discharge satisfies a full-window discharge cutoff condition of each battery cell, and each of the battery cells is allowed to stand for a first time at the target ambient temperature, until each of the battery cells is allowed to stand to a preset ambient temperature;

[0012] Performing a first constant current charge on each battery cell after the first rest at a second preset rate until the battery cell is charged to meet the first charging cutoff condition of the full window of each battery cell, switching to a third preset rate to perform a second constant current charge on each battery cell until the battery cell is charged to meet the second charging cutoff condition of the full window of each battery cell, and performing a second rest on each battery cell at the target ambient temperature until the battery cell is rested to the target ambient temperature;

[0013] Based on the target ambient temperature, each battery cell is discharged at a fourth preset rate for a second constant current discharge to obtain a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, and a discharge current of the battery system.

[0014] According to one embodiment of the present application, obtaining a third voltage of each battery cell before charging, a fourth voltage of each battery cell after charging, and a charging current of the battery system in a battery system at a target state of charge includes:

[0015] Allowing each battery cell to rest for a third time at the target ambient temperature, and after the resting time is set, replenishing current to each battery cell at a fifth preset rate until the replenished power of the battery system integrated with each battery cell is equal to the discharge capacity of the battery system;

[0016] At the target ambient temperature, each battery cell is allowed to rest for a fourth time until each battery cell is allowed to rest to the target ambient temperature, and each battery cell is charged with a constant current for a third time at a sixth preset rate to obtain a third voltage of each battery cell in the battery system before charging, a fourth voltage of each battery cell after charging, and a charging current of the battery system.

[0017] According to one embodiment of the present application, determining the target discharge internal resistance value of each battery cell and the target charge internal resistance value of each battery cell includes:

[0018] Obtain the DC internal resistance data of each battery cell when it is powered off;

[0019] Extracting a first preset number of DC internal resistance data samples from the DC internal resistance data, and obtaining a second preset number of DC internal resistance data after extracting a preset number of times;

[0020] obtaining the second preset number of discharge internal resistance extreme value differences and the second preset number of charge internal resistance extreme value differences based on the second preset number of DC internal resistance data;

[0021] Calculate the sample mean and sample standard deviation of the DC internal resistance data sample based on a preset normal distribution strategy;

[0022] According to the sample mean and the sample standard deviation, a preset distribution principle is used to obtain the discharge internal resistance variation range of each battery cell and the charging internal resistance variation range of each battery cell, and the upper limit value of the discharge internal resistance variation range is used as the discharge internal resistance target value, and the upper limit value of the charging internal resistance variation range is used as the charging internal resistance target value.

[0023] According to one embodiment of the present application, after determining the target discharge internal resistance value of each battery cell and the target charge internal resistance value of each battery cell, the method further includes:

[0024] If the extreme difference in discharge internal resistance is greater than the target discharge internal resistance value, or the extreme difference in charge internal resistance is greater than the target charge internal resistance value, it is determined that the battery system does not meet the internal resistance consistency evaluation, and the battery cell with the smallest internal resistance in the battery system is replaced until the battery system meets the internal resistance consistency evaluation.

[0025] According to the method for evaluating the consistency of the internal resistance of batteries in an embodiment of the present application, the first voltage of each battery cell before discharge, the second voltage of each battery cell after discharge, the discharge current of the battery system, the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging, and the charging current of the battery system are obtained. The discharge internal resistance of each battery cell is calculated according to the first voltage, the second voltage, and the discharge current, and the maximum discharge internal resistance and the minimum discharge internal resistance are recorded, and then the discharge internal resistance extreme value difference of each battery cell is calculated; the charging internal resistance of each battery cell is calculated according to the third voltage, the fourth voltage, and the charging current, and the maximum charging internal resistance and the minimum charging internal resistance are recorded, and then the charging internal resistance extreme value difference of each battery cell is calculated. When the discharge internal resistance is less than or equal to the target value and the charging internal resistance extreme difference is less than or equal to the charging internal resistance target value, the battery system is judged to meet the internal resistance consistency assessment. This solves the problem that the relevant technology cannot capture the internal resistance changes under dynamic working conditions, and lacks a quantitative standard for internal resistance consistency judgment, making it difficult to adapt to different battery systems, and thus unable to accurately monitor the battery health status for different battery systems. By recording the charging and discharging current in the battery system, the voltage of the battery cell before and after discharge and charging, calculating the maximum and minimum internal resistance of all battery cells, and then calculating the battery system internal resistance extreme difference, and comparing the internal resistance extreme difference with the internal resistance consistency target value, it can be determined whether the battery system meets the internal resistance consistency design requirements.

[0026] A second embodiment of the present application provides a device for evaluating battery internal resistance consistency, comprising:

[0027] an acquisition module, configured to acquire a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, a discharge current of the battery system, a third voltage of each battery cell before charge, a fourth voltage of each battery cell after charge, and a charge current of the battery system in a battery system at a target state of charge;

[0028] a first calculation module, configured to calculate a discharge internal resistance of each battery cell according to the first voltage of each battery cell before discharge, the second voltage of each battery cell after discharge, and the discharge current, and record a maximum discharge internal resistance and a minimum discharge internal resistance among all battery cells, so as to calculate a discharge internal resistance extreme value difference of each battery cell according to the maximum discharge internal resistance and the minimum discharge internal resistance;

[0029] a second calculation module, configured to calculate a charging internal resistance of each battery cell according to the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging, and the charging current, and record a maximum charging internal resistance and a minimum charging internal resistance among all the battery cells, so as to calculate a charging internal resistance extreme value difference of each battery cell according to the maximum charging internal resistance and the minimum charging internal resistance;

[0030] A determination module is configured to determine a target discharge internal resistance value for each battery cell and a target charge internal resistance value for each battery cell, and determine that the battery system satisfies an internal resistance consistency assessment if the extreme value difference in discharge internal resistance is less than or equal to the target discharge internal resistance value, and the extreme value difference in charge internal resistance is less than or equal to the target charge internal resistance value.

[0031] According to one embodiment of the present application, the acquisition module includes:

[0032] a rest unit, configured to perform a first constant current discharge on each of the battery cells at a first preset rate based on a target ambient temperature until the discharge satisfies a full-window discharge cutoff condition of each battery cell, and to perform a first rest on each of the battery cells at the target ambient temperature until each of the battery cells is rested to a preset ambient temperature;

[0033] a first charging unit, configured to perform a first constant current charging on each battery cell after the first rest at a second preset rate until the battery cell is charged to meet a first charging cutoff condition of the full window of each battery cell, switch to a third preset rate to perform a second constant current charging on each battery cell until the battery cell is charged to meet a second charging cutoff condition of the full window of each battery cell, and perform a second rest on each battery cell at the target ambient temperature until the battery cell is rested to the target ambient temperature;

[0034] The discharge unit is used to perform a second constant current discharge on each battery cell at a fourth preset rate based on the target ambient temperature to obtain a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, and a discharge current of the battery system.

[0035] According to one embodiment of the present application, the acquisition module includes:

[0036] a current replenishing unit, configured to place each battery cell at a target ambient temperature for a third time, and after a preset resting time, replenish current to each battery cell at a fifth preset rate until the replenished power of the battery system integrated with each battery cell is equal to the discharge capacity of the battery system;

[0037] The second charging unit is used to perform a fourth resting of each battery cell at the target ambient temperature until each battery cell is rested to the target ambient temperature, and perform a third constant current charging of each battery cell at a sixth preset rate to obtain a third voltage of each battery cell in the battery system before charging, a fourth voltage of each battery cell after charging, and a charging current of the battery system.

[0038] According to one embodiment of the present application, the determination module includes:

[0039] The first acquisition unit is used to obtain the DC internal resistance data of each battery cell when it is powered off;

[0040] an extraction unit, configured to extract a first preset number of DC internal resistance data samples from the DC internal resistance data, and obtain a second preset number of DC internal resistance data after extracting a preset number of times;

[0041] a second acquiring unit, configured to obtain the second preset number of discharge internal resistance extreme value differences and the second preset number of charge internal resistance extreme value differences based on the second preset number of DC internal resistance data;

[0042] A calculation unit, configured to calculate a sample mean and a sample standard deviation of the DC internal resistance data sample based on a preset normal distribution strategy;

[0043] a third acquisition unit, configured to obtain, according to the sample mean and the sample standard deviation, the discharge internal resistance variation range of each battery cell and the charging internal resistance variation range of each battery cell using a preset distribution principle, and to use the upper limit value of the discharge internal resistance variation range as the discharge internal resistance target value, and to use the upper limit value of the charging internal resistance variation range as the charging internal resistance target value.

[0044] According to one embodiment of the present application, after determining the target discharge internal resistance value of each battery cell and the target charge internal resistance value of each battery cell, the determination module further includes:

[0045] a determination unit, configured to determine that the battery system does not satisfy an internal resistance consistency evaluation if the extreme difference in discharge internal resistance is greater than the target discharge internal resistance value, or if the extreme difference in charge internal resistance is greater than the target charge internal resistance value, and replace the battery cell with the smallest internal resistance in the battery system until the battery system satisfies the internal resistance consistency evaluation.

[0046] According to the battery internal resistance consistency evaluation device of the embodiment of the present application, the first voltage of each battery cell before discharge, the second voltage of each battery cell after discharge, the discharge current of the battery system, the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging and the charging current of the battery system are obtained. The discharge internal resistance of each battery cell is calculated according to the first voltage, the second voltage and the discharge current, and the maximum discharge internal resistance and the minimum discharge internal resistance are recorded, and then the discharge internal resistance extreme value difference of each battery cell is calculated; the charging internal resistance of each battery cell is calculated according to the third voltage, the fourth voltage and the charging current, and the maximum charging internal resistance and the minimum charging internal resistance are recorded, and then the charging internal resistance extreme value difference of each battery cell is calculated. When the discharge internal resistance is less than or equal to the target value and the charging internal resistance extreme difference is less than or equal to the charging internal resistance target value, the battery system is judged to meet the internal resistance consistency assessment. This solves the problem that the relevant technology cannot capture the internal resistance changes under dynamic working conditions, and lacks a quantitative standard for internal resistance consistency judgment, making it difficult to adapt to different battery systems, and thus unable to accurately monitor the battery health status for different battery systems. By recording the charging and discharging current in the battery system, the voltage of the battery cell before and after discharge and charging, calculating the maximum and minimum internal resistance of all battery cells, and then calculating the battery system internal resistance extreme difference, and comparing the internal resistance extreme difference with the internal resistance consistency target value, it can be determined whether the battery system meets the internal resistance consistency design requirements.

[0047] A third aspect of the present application provides a vehicle, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the battery internal resistance consistency evaluation method as described in the above embodiment.

[0048] A fourth aspect of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the battery internal resistance consistency evaluation method as described in the above embodiment.

[0049] A fifth aspect of the present application provides a computer program product, including a computer program, which is executed to implement the method for evaluating the consistency of battery internal resistance as described in the above embodiment.

[0050] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0052] Figure 1A flowchart of a method for evaluating battery internal resistance consistency according to an embodiment of the present application;

[0053] Figure 2 This is an overall flow chart of battery internal resistance consistency evaluation according to one embodiment of the present application;

[0054] Figure 3 This is a diagram of the discharge internal resistance distribution of a battery system according to one embodiment of the present application;

[0055] Figure 4 A charging internal resistance distribution diagram of a battery system according to one embodiment of the present application;

[0056] Figure 5 This is an example diagram of a device for evaluating battery internal resistance consistency according to an embodiment of the present application;

[0057] Figure 6 Schematic diagram of the structure of a vehicle according to an embodiment of the present application. DETAILED DESCRIPTION

[0058] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0059] The following describes the method, device, vehicle and storage medium for evaluating the consistency of the internal resistance of batteries according to the embodiments of the present application with reference to the accompanying drawings. In view of the problem that the related technologies mentioned in the above background technology cannot capture the changes in internal resistance under dynamic working conditions, and lack a quantitative standard for judging the consistency of internal resistance, and are difficult to adapt to different battery systems, and thus cannot accurately monitor the battery health status for different battery systems, the present application provides a method for evaluating the consistency of the internal resistance of batteries. In this method, the first voltage of each battery cell before discharge, the second voltage of each battery cell after discharge, the discharge current of the battery system, the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging and the charging current of the battery system are obtained at the target state of charge. The discharge internal resistance of each battery cell is calculated based on the first voltage, the second voltage and the discharge current, and the maximum discharge internal resistance and the minimum discharge internal resistance are recorded, and then the discharge internal resistance extreme value difference of each battery cell is calculated; the discharge internal resistance of each battery cell is calculated based on the third voltage, the fourth voltage and the charging current. Charging internal resistance, and record the maximum charging internal resistance and the minimum charging internal resistance, and then calculate the charging internal resistance extreme difference of each battery cell. When the discharge internal resistance extreme difference is less than or equal to the discharge internal resistance target value and the charging internal resistance extreme difference is less than or equal to the charging internal resistance target value, the battery system is judged to meet the internal resistance consistency assessment. This solves the problem that the relevant technology cannot capture the internal resistance changes under dynamic conditions, and lacks a quantitative standard for internal resistance consistency judgment, making it difficult to adapt to different battery systems, and thus unable to accurately monitor the battery health status for different battery systems. By recording the charging and discharging current in the battery system, the voltage of the battery cell before and after discharge and charging, calculating the maximum and minimum internal resistance of all battery cells, and then calculating the battery system internal resistance extreme difference, and comparing the internal resistance extreme difference with the internal resistance consistency target value, it can be determined whether the battery system meets the internal resistance consistency design requirements.

[0060] Specifically, Figure 1 A flowchart of a method for evaluating the consistency of battery internal resistance provided in an embodiment of the present application.

[0061] like Figure 1 As shown, the method for evaluating the consistency of the battery internal resistance includes the following steps:

[0062] In step S101, a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, a discharge current of the battery system, a third voltage of each battery cell before charging, a fourth voltage of each battery cell after charging, and a charging current of the battery system are obtained in a battery system at a target state of charge.

[0063] According to one embodiment of the present application, a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, and a discharge current of the battery system in a battery system at a target state of charge are obtained, including: based on the target ambient temperature, performing a first constant current discharge on each battery cell at a first preset rate until the discharge satisfies the full window discharge cutoff condition of each battery cell, and performing a first rest on each battery cell at the target ambient temperature until each battery cell is rested at the preset ambient temperature; performing a first constant current charge on each battery cell after the first rest at a second preset rate until the charge satisfies the first charge cutoff condition of the full window of each battery cell, switching to a third preset rate to perform a second constant current charge on each battery cell until the charge satisfies the second charge cutoff condition of the full window of each battery cell, and performing a second rest on each battery cell at the target ambient temperature until each battery cell is rested at the target ambient temperature; based on the target ambient temperature, performing a second constant current discharge on each battery cell at a fourth preset rate to obtain the first voltage of each battery cell before discharge, the second voltage of each battery cell after discharge, and the discharge current of the battery system.

[0064] Among them, the preset ambient temperature, the first preset magnification, the second preset magnification, the third preset magnification and the fourth preset magnification can all be set by those skilled in the art according to actual test requirements and are not specifically limited here.

[0065] Specifically, in order to solve the problem of internal resistance consistency of the battery system caused by inconsistent status of each battery cell, the embodiment of the present application evaluates the internal resistance consistency of the battery system through extreme value difference, and uses probability distribution to obtain the target value of internal resistance consistency of the battery cell or battery system (i.e., charging internal resistance target value and discharging internal resistance target value) to characterize the consistency of the internal resistance of the battery cell or battery system, thereby helping to effectively evaluate the status of the sample before the battery is installed on the vehicle, and avoid problems such as increased temperature difference, battery attenuation, and decreased power performance due to poor internal resistance consistency.

[0066] Specifically, if Figure 2 As shown, the embodiment of the present application is equipped with a room temperature pulse power test of a battery cell or a battery system. First, based on the target ambient temperature (for example, 25°C±2°C), each battery cell is discharged at a first preset rate (for example, a 1 / 3C rate) for the first time. To ensure the discharge safety of the battery cell, the embodiment of the present application needs to discharge each battery cell until the full window discharge cutoff condition of each battery cell is met, that is, the lowest voltage limit allowed to be reached by the battery cell during the discharge process, so as to avoid continuing to discharge beyond this limit, which may cause irreversible damage to the battery or affect its service life. Therefore, when each battery cell is discharged at a constant current for the first time to meet the full window discharge cutoff condition of each battery cell, the system will automatically stop discharging to protect the battery system from the harm of over-discharge.

[0067] The C in the 1 / 3C rate refers to the rated capacity of the battery. For example, if the rated capacity of the battery is 3000mAh, then 1 / 3C is 1000mA.

[0068] Secondly, at the target ambient temperature, each battery cell is left to rest for the first time until each battery cell reaches a preset ambient temperature (for example, the difference between the battery cell temperature and the target ambient temperature is no more than 2°C), and then each battery cell is charged with a constant current for the first time at a second preset rate (for example, a 1 / 3C rate) to quickly increase the power of the battery system to a state close to full charge, so as to replenish a large amount of energy for the battery in a relatively short time. To ensure the charging safety of the battery cell, the embodiment of the present application also needs to charge each battery cell to meet the first charging cutoff condition of the full window of each battery cell, that is, the highest voltage limit allowed to be reached by the battery cell during the charging process, so as to avoid continuing to charge beyond this limit, which may cause irreversible damage to the battery or affect its service life.

[0069] Again, after charging each battery cell to meet the first charging cutoff condition of the full window of each battery cell, at this time, the battery voltage is close to its maximum value, and it is necessary to switch to the third preset rate (for example, 0.05C rate) to perform a second constant current charging on each battery cell until it is charged to meet the second charging cutoff condition of the full window of each battery cell, and then each battery cell is left to rest for a second time until each battery cell is left to rest to the target ambient temperature.

[0070] The C in the 0.05C rate also refers to the rated capacity of the battery. For example, if the rated capacity of the battery is 3000mAh, then 0.05C is 150mA.

[0071] It should be noted that when each cell in the battery system is charged to a nearly full state, it is necessary to switch to a smaller charging current to continue charging each cell in order to achieve more precise control of the charging process, avoid overcharging, and ensure that each cell can reach its maximum safe voltage level.

[0072] Finally, based on the target ambient temperature, each battery cell is discharged for a second time at a fourth preset rate (for example, a 1 / 3C rate) until the discharge capacity Qloss reaches the target SOC (State of Charge) of the system test, where the discharge is stopped, wherein the discharge capacity Qloss = battery system rated capacity × (1-target SOC). Each battery cell is then left to rest at the target ambient temperature and discharged at a constant current of 3C for ts (for example, 10s). At this time, the first voltage Va of each battery cell before discharge, the second voltage Vb of each battery cell after discharge, the discharge current I1 and the discharge capacity Qloss of the battery system are obtained at the target SOC.

[0073] That is to say, under the normal temperature pulse power test, first, each battery cell is discharged at a constant current rate of 1 / 3C for the first time at the target ambient temperature of 25℃±2℃ until the discharge is stopped at the full window discharge cutoff condition of each battery cell, and each battery cell is left to stand for the first time at the target ambient temperature of 25℃±2℃, so that the difference between the battery cell temperature and the target ambient temperature is not higher than 2℃; then, each battery cell is charged at a constant current rate of 1 / 3C for the first time until it is charged to the first charge cutoff condition of the full window of each battery cell, and then the rate is switched to 0.05C for each battery cell. The second constant current charging is performed until the second charging cutoff condition of the full window of each battery cell is met. Finally, each battery cell is allowed to rest for a second time until each battery cell is allowed to rest to 25℃±2℃, and then each battery cell is discharged for a second time at a constant current rate of 1 / 3C to the target SOC and then stopped discharging. After each battery cell is allowed to rest to 25℃±2℃, it is discharged at a constant current of 3C for 10s, so that the first voltage Va of each battery cell before discharge, the second voltage Vb of each battery cell after discharge, the discharge current I1 and the discharge capacity Qloss of the battery system under the target SOC can be obtained.

[0074] In step S102, the discharge internal resistance of each battery cell is calculated based on the first voltage of each battery cell before discharge, the second voltage of each battery cell after discharge, and the discharge current, and the maximum discharge internal resistance and the minimum discharge internal resistance of all battery cells are recorded to calculate the discharge internal resistance extreme value difference of each battery cell based on the maximum discharge internal resistance and the minimum discharge internal resistance.

[0075] Specifically, based on the first voltage Va of each battery cell before discharge, the second voltage Vb of each battery cell after discharge, the discharge current I1 and the discharge capacity Qloss of the battery system under the target SOC obtained above, the discharge internal resistance R of each battery cell can be calculated based on the first voltage Va, the second voltage Vb and the discharge current I1. dis , which can be expressed as R dis =(Vb-Va) / I1, and record the maximum discharge internal resistance R of all cells dismax and minimum discharge internal resistance R dismin ,like Figure 3 As shown, the discharge internal resistance R dis The distribution range is 0.73~0.77mΩ. At this time, the maximum discharge internal resistance R dismax and minimum discharge internal resistance R dismin Calculate the discharge internal resistance extreme value difference △R of each battery cell dis , that is, △R dis =R dismax -R dismin =0.04mΩ.

[0076] In step S103, the charging internal resistance of each battery cell is calculated based on the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging, and the charging current, and the maximum charging internal resistance and the minimum charging internal resistance of all battery cells are recorded to calculate the charging internal resistance extreme value difference of each battery cell based on the maximum charging internal resistance and the minimum charging internal resistance.

[0077] According to one embodiment of the present application, a third voltage of each battery cell before charging, a fourth voltage of each battery cell after charging, and a charging current of the battery system are obtained in a battery system at a target state of charge, including: allowing each battery cell to rest for a third time at a target ambient temperature, and after a preset resting time, supplementing current to each battery cell at a fifth preset rate until the supplemented power of the battery system integrated with each battery cell is equal to the discharge capacity of the battery system; allowing each battery cell to rest for a fourth time at the target ambient temperature until each battery cell rests to the target ambient temperature, and performing constant current charging on each battery cell for a third time at a sixth preset rate, to obtain the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging, and the charging current of the battery system.

[0078] The preset time and the fifth preset magnification can be set by those skilled in the art according to actual test requirements and are not specifically limited here.

[0079] Specifically, in order to ensure that the battery system can accurately restore to the previous target state of charge, so as to carry out more accurate subsequent measurement and analysis, it is necessary to replenish the discharged discharge capacity Qloss so that the battery system will be in a known and controllable state, that is, each battery cell is left to rest for a third time at the target ambient temperature, and after a preset resting time (for example, 40s), each battery cell is supplemented with current at a fifth preset rate (for example, a 0.1C rate) until the supplemented power of the battery system integrated in each battery cell is equal to the discharge capacity Qloss of the battery system. Then, each battery cell is left to rest for a fourth time until each battery cell is rested to the target ambient temperature, and each battery cell is charged with a third constant current at a sixth preset rate (for example, a 2.25C rate) (for example, charging for 10s) to obtain a third voltage Vc of each battery cell in the battery system before charging, a fourth voltage Vd of each battery cell after charging, and a charging current I2 of the battery system.

[0080] That is to say, after each battery cell is allowed to stand at the target ambient temperature for 40 seconds, each battery cell is supplemented with current at a rate of 0.1C until the supplemented capacity of the battery system integrated in each battery cell is equal to the discharge capacity Qloss of the battery system. Then, after each battery cell is allowed to stand at 25℃±2℃, each battery cell is charged with a third constant current for 10 seconds at a rate of 2.25C, and the third voltage Vc of each battery cell before charging, the fourth voltage Vd of each battery cell after charging, and the charging current I2 of the battery system are recorded.

[0081] Therefore, the charging internal resistance R of each battery cell can be calculated according to the third voltage Vc, the fourth voltage Vd and the charging current I2. char , which can be expressed as R char =(Vd-Vc) / I2, and record the maximum charging internal resistance R of all cells charmax and minimum charging internal resistance R charmin ,like Figure 4 As shown, the charging internal resistance R char The distribution range is 0.84~0.90mΩ. At this time, the maximum charging internal resistance R charmax and minimum charging internal resistance R charmin Calculate the charging internal resistance extreme difference △R of each battery cell char , that is, △R char =R charmax -R charmin =0.06mΩ.

[0082] In step S104, the discharge internal resistance target value of each battery cell and the charging internal resistance target value of each battery cell are determined. If the discharge internal resistance extreme value difference is less than or equal to the discharge internal resistance target value, and the charging internal resistance extreme value difference is less than or equal to the charging internal resistance target value, it is determined that the battery system meets the internal resistance consistency assessment.

[0083] According to one embodiment of the present application, determining the discharge internal resistance target value of each battery cell and the charging internal resistance target value of each battery cell includes: obtaining DC internal resistance data of each battery cell when it is powered off; extracting a first preset number of DC internal resistance data samples from the DC internal resistance data, and obtaining a second preset number of DC internal resistance data after extracting the preset number of times; obtaining a second preset number of discharge internal resistance extreme value differences and a second preset number of charging internal resistance extreme value differences based on the second preset number of DC internal resistance data; calculating the sample mean and sample standard deviation of the DC internal resistance data samples based on a preset normal distribution strategy; according to the sample mean and the sample standard deviation, using a preset distribution principle to obtain the discharge internal resistance variation range of each battery cell and the charging internal resistance variation range of each battery cell, and using the upper limit value of the discharge internal resistance variation range as the discharge internal resistance target value, and using the upper limit value of the charging internal resistance variation range as the charging internal resistance target value.

[0084] Among them, the first preset number, the second preset number, the preset number of times, the preset normal distribution strategy and the preset distribution principle can all be set by those skilled in the art according to actual testing requirements and are not specifically limited here.

[0085] Specifically, in the embodiment of the present application, a probability statistics method is used to obtain the internal resistance consistency target value. First, the DC internal resistance data (i.e., DCR (Direct Current Resistance) data) of each battery cell when it is powered off is obtained, and a first preset number (e.g., n) of DC internal resistance data samples are extracted from the DC internal resistance data. After extracting a preset number of times (e.g., 1000 times), a second preset number (e.g., 1000 groups) of DC internal resistance data are obtained. According to △R dis =R dismax -R dismin and △R char =R charmax -R charmin , for each set of DC internal resistance data, a discharge internal resistance extreme value difference △R can be calculated dis and the charging internal resistance extreme value difference △R char , then a total of 1000 △R can be obtained dis and 1000 △R char Secondly, according to the preset normal distribution strategy, the preset distribution principle is used to obtain the discharge internal resistance variation range of each battery cell (for example, μ-3σ≤△R dis ≤μ+3σ) and the charging internal resistance variation range of each battery cell (for example, μ-3σ≤△R char ≤μ+3σ), and the upper limit value of the discharge internal resistance change range (μ+3σ) is used as the discharge internal resistance target value △R0 dis , and the upper limit of the charging internal resistance variation range is used as the charging internal resistance target value △R0 char .

[0086] That is to say, using the discharge DCR data of the battery cell, the data sample size is n, and m (m≤n) are randomly selected each time, and 1000 samples are drawn with replacement, 1000 sets of DCR data can be obtained. According to △R dis =R dismax -R dismin and △R char =R charmax -R charmin , calculate a △R for each set of DCR data dis and △R char , then 1000 △R dis Values ​​and 1000 △R char Then, according to the general normal distribution, μ is the sample mean, σ is the sample standard deviation, when 1000 △R dis The value satisfies μ-3σ≤△R dis When ≤μ+3σ, △R disThere is a 99.73% probability of falling within this range. At this time, [μ-3σ, μ+3σ] is called the normal fluctuation range. Therefore, μ+3σ is used as the discharge internal resistance target value or the charge internal resistance target value. For example, if μ dis =0.1mΩ, σ dis =0.015mΩ, then △R0 dis =μ dis +3σ dis =0.1mΩ+3x0.015 mΩ=0.145mΩ≈0.14mΩ, that is, △R0 dis =μ+3σ=0.14mΩ; Similarly, assuming μ char =0.12mΩ, σ char =0.013mΩ, then △R0 char =μ char +3σ char =0.12mΩ+3x0.013 mΩ=0.159mΩ≈0.16mΩ, that is, △R0 char =0.16mΩ.

[0087] Where, μ=(△R dis，1 +△R dis，2 +‥‥‥+△R dis，1000 ) / 1000;

[0088] σ=[∑(△R dis,i- μ) 2 / (1000-1)] 1 / 2

[0089] Furthermore, for the internal resistance consistency evaluation of each cell or battery system, if the discharge internal resistance extreme value difference △R dis Less than or equal to the discharge internal resistance target value △R0 dis , and the charging internal resistance extreme value difference △R char Less than or equal to the charging internal resistance target value △R0 char , then the battery system is judged to meet the internal resistance consistency assessment, that is, if △R dis ≤△R0 dis And △R char ≤△R0 char , proving that the internal resistance consistency of the battery cell or battery system is qualified.

[0090] According to one embodiment of the present application, after determining the discharge internal resistance target value of each battery cell and the charging internal resistance target value of each battery cell, it also includes: if the discharge internal resistance extreme value difference is greater than the discharge internal resistance target value, or the charging internal resistance extreme value difference is greater than the charging internal resistance target value, it is determined that the battery system does not meet the internal resistance consistency evaluation, and the battery cell with the smallest internal resistance in the battery system is replaced until the battery system meets the internal resistance consistency evaluation.

[0091] Specifically, if the discharge internal resistance extreme value difference △R dis Greater than the discharge internal resistance target value △R0 dis , or the charging internal resistance extreme value difference △R char Greater than the charging internal resistance target value △R0 char , that is, △R dis >△R0 dis , or △R char >△R0 char If the battery system is determined to not meet the internal resistance consistency assessment, which will affect the electric vehicle's range and power performance during long-term use, the battery cell with the smallest internal resistance in the battery system needs to be replaced until the battery system meets the internal resistance consistency assessment.

[0092] In the embodiment of the present application, based on the above example, the calculated discharge internal resistance extreme value difference △R dis =0.04mΩ<discharge internal resistance target value △R0 dis =0.14mΩ, charging internal resistance extreme value difference △R char =0.06mΩ<Charging internal resistance target value △R0 char =0.16mΩ, indicating that the internal resistance consistency of the battery system meets the design requirements for the internal resistance consistency of the battery system.

[0093] In summary, it can be seen from the above test results that the detection of the internal resistance consistency of the power battery system of the embodiment of the present application is carried out after the normal temperature pulse power test. By recording the pulse charge and discharge current in the battery system, the voltage of the battery cell before and after pulse discharge and charging, and referring to the DC internal resistance calculation method, the internal resistance of all battery cells in the system is obtained, and the battery system internal resistance extreme value difference is calculated according to the maximum and minimum values ​​of the battery cell internal resistance. Then, the probability statistics method is used to obtain the target value of the internal resistance consistency of the battery cell or battery system, and the internal resistance extreme value difference obtained by the test is compared with the battery system internal resistance consistency target value, so as to determine whether the power battery system meets the internal resistance consistency design requirements.

[0094] According to the method for evaluating the consistency of the internal resistance of batteries in an embodiment of the present application, the first voltage of each battery cell before discharge, the second voltage of each battery cell after discharge, the discharge current of the battery system, the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging, and the charging current of the battery system are obtained. The discharge internal resistance of each battery cell is calculated according to the first voltage, the second voltage, and the discharge current, and the maximum discharge internal resistance and the minimum discharge internal resistance are recorded, and then the discharge internal resistance extreme value difference of each battery cell is calculated; the charging internal resistance of each battery cell is calculated according to the third voltage, the fourth voltage, and the charging current, and the maximum charging internal resistance and the minimum charging internal resistance are recorded, and then the charging internal resistance extreme value difference of each battery cell is calculated. When the discharge internal resistance is less than or equal to the target value and the charging internal resistance extreme difference is less than or equal to the charging internal resistance target value, the battery system is judged to meet the internal resistance consistency assessment. This solves the problem that the relevant technology cannot capture the internal resistance changes under dynamic working conditions, and lacks a quantitative standard for internal resistance consistency judgment, making it difficult to adapt to different battery systems, and thus unable to accurately monitor the battery health status for different battery systems. By recording the charging and discharging current in the battery system, the voltage of the battery cell before and after discharge and charging, calculating the maximum and minimum internal resistance of all battery cells, and then calculating the battery system internal resistance extreme difference, and comparing the internal resistance extreme difference with the internal resistance consistency target value, it can be determined whether the battery system meets the internal resistance consistency design requirements.

[0095] Figure 5 4 is a block diagram of a device for evaluating battery internal resistance consistency according to an embodiment of the present application.

[0096] like Figure 5 As shown, the battery internal resistance consistency evaluation device 10 includes: an acquisition module 100 , a first calculation module 200 , a second calculation module 300 and a determination module 400 .

[0097] The acquisition module 100 is configured to acquire a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, a discharge current of the battery system, a third voltage of each battery cell before charging, a fourth voltage of each battery cell after charging, and a charging current of the battery system in a battery system at a target state of charge;

[0098] a first calculation module 200, configured to calculate a discharge internal resistance of each battery cell based on a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, and a discharge current, and to record a maximum discharge internal resistance and a minimum discharge internal resistance among all battery cells, so as to calculate a discharge internal resistance extreme value difference of each battery cell based on the maximum discharge internal resistance and the minimum discharge internal resistance;

[0099] a second calculating module 300, configured to calculate a charging internal resistance of each battery cell based on the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging, and the charging current, and to record a maximum charging internal resistance and a minimum charging internal resistance among all the battery cells, so as to calculate a charging internal resistance extreme value difference of each battery cell based on the maximum charging internal resistance and the minimum charging internal resistance;

[0100] The determination module 400 is used to determine the discharge internal resistance target value of each battery cell and the charging internal resistance target value of each battery cell. If the discharge internal resistance extreme value difference is less than or equal to the discharge internal resistance target value, and the charging internal resistance extreme value difference is less than or equal to the charging internal resistance target value, it is determined that the battery system meets the internal resistance consistency assessment.

[0101] According to one embodiment of the present application, the acquisition module 100 includes:

[0102] A rest unit is used to perform a first constant current discharge on each battery cell at a first preset rate based on the target ambient temperature until the discharge meets the full window discharge cutoff condition of each battery cell, and to perform a first rest on each battery cell at the target ambient temperature until each battery cell is rested to the preset ambient temperature;

[0103] a first charging unit, configured to perform a first constant current charging on each battery cell after the first rest at a second preset rate until the battery cell is charged to meet a first charging cutoff condition of the full window of each battery cell, then switch the charging to a third preset rate to perform a second constant current charging on each battery cell until the battery cell is charged to meet a second charging cutoff condition of the full window of each battery cell, and perform a second rest on each battery cell at a target ambient temperature until each battery cell is rested to the target ambient temperature;

[0104] The discharge unit is used to perform a second constant current discharge on each battery cell at a fourth preset rate based on the target ambient temperature to obtain a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, and a discharge current of the battery system.

[0105] According to one embodiment of the present application, the acquisition module 100 includes:

[0106] a current replenishing unit, configured to place each battery cell at a target ambient temperature for a third time, and after a preset resting time, replenish current to each battery cell at a fifth preset rate until the replenished capacity of the battery system integrated with each battery cell is equal to the discharge capacity of the battery system;

[0107] The second charging unit is used to perform a fourth resting of each battery cell at a target ambient temperature until each battery cell is cooled to the target ambient temperature, and perform a third constant current charging of each battery cell at a sixth preset rate to obtain a third voltage of each battery cell in the battery system before charging, a fourth voltage of each battery cell after charging, and a charging current of the battery system.

[0108] According to one embodiment of the present application, the determination module 400 includes:

[0109] The first acquisition unit is used to obtain the DC internal resistance data of each battery cell when it is powered off;

[0110] an extraction unit, configured to extract a first preset number of DC internal resistance data samples from the DC internal resistance data, and obtain a second preset number of DC internal resistance data after extracting the samples a preset number of times;

[0111] a second acquiring unit, configured to obtain a second preset number of discharge internal resistance extreme value differences and a second preset number of charge internal resistance extreme value differences based on a second preset number of DC internal resistance data;

[0112] A calculation unit, configured to calculate a sample mean and a sample standard deviation of the DC internal resistance data sample based on a preset normal distribution strategy;

[0113] The third acquisition unit is used to obtain the discharge internal resistance variation range of each battery cell and the charging internal resistance variation range of each battery cell according to the sample mean and the sample standard deviation using a preset distribution principle, and use the upper limit value of the discharge internal resistance variation range as the discharge internal resistance target value, and use the upper limit value of the charging internal resistance variation range as the charging internal resistance target value.

[0114] According to one embodiment of the present application, after determining the target discharge internal resistance value of each battery cell and the target charge internal resistance value of each battery cell, the determination module 400 further includes:

[0115] A determination unit is configured to determine that the battery system does not meet the internal resistance consistency assessment if the extreme difference in discharge internal resistance is greater than the target discharge internal resistance, or if the extreme difference in charge internal resistance is greater than the target charge internal resistance, and replace the battery cell with the smallest internal resistance in the battery system until the battery system meets the internal resistance consistency assessment.

[0116] According to the battery internal resistance consistency evaluation device of the embodiment of the present application, the first voltage of each battery cell before discharge, the second voltage of each battery cell after discharge, the discharge current of the battery system, the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging and the charging current of the battery system are obtained. The discharge internal resistance of each battery cell is calculated according to the first voltage, the second voltage and the discharge current, and the maximum discharge internal resistance and the minimum discharge internal resistance are recorded, and then the discharge internal resistance extreme value difference of each battery cell is calculated; the charging internal resistance of each battery cell is calculated according to the third voltage, the fourth voltage and the charging current, and the maximum charging internal resistance and the minimum charging internal resistance are recorded, and then the charging internal resistance extreme value difference of each battery cell is calculated. When the discharge internal resistance is less than or equal to the target value and the charging internal resistance extreme difference is less than or equal to the charging internal resistance target value, the battery system is judged to meet the internal resistance consistency assessment. This solves the problem that the relevant technology cannot capture the internal resistance changes under dynamic working conditions, and lacks a quantitative standard for internal resistance consistency judgment, making it difficult to adapt to different battery systems, and thus unable to accurately monitor the battery health status for different battery systems. By recording the charging and discharging current in the battery system, the voltage of the battery cell before and after discharge and charging, calculating the maximum and minimum internal resistance of all battery cells, and then calculating the battery system internal resistance extreme difference, and comparing the internal resistance extreme difference with the internal resistance consistency target value, it can be determined whether the battery system meets the internal resistance consistency design requirements.

[0117] Figure 6 A schematic diagram of the structure of a vehicle provided in an embodiment of the present application. The vehicle may include:

[0118] A memory 601 , a processor 602 , and a computer program stored in the memory 601 and executable on the processor 602 .

[0119] When the processor 602 executes the program, the method for evaluating the consistency of the internal resistance of the battery provided in the above embodiment is implemented.

[0120] Furthermore, the vehicle further comprises:

[0121] The communication interface 603 is used for communication between the memory 601 and the processor 602 .

[0122] The memory 601 is used to store computer programs that can be run on the processor 602 .

[0123] The memory 601 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0124] If the memory 601, processor 602, and communication interface 603 are implemented independently, the communication interface 603, memory 601, and processor 602 can be interconnected via a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 6 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0125] Optionally, in a specific implementation, if the memory 601, the processor 602 and the communication interface 603 are integrated on a chip, the memory 601, the processor 602 and the communication interface 603 can communicate with each other through an internal interface.

[0126] The processor 602 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0127] This embodiment further provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the above-mentioned method for evaluating the consistency of the internal resistance of a battery is implemented.

[0128] This embodiment further provides a computer program product, including a computer program. The computer program is executed to implement the battery internal resistance consistency evaluation method of the above embodiment.

[0129] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations 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 N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0130] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0131] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0132] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or N wires (electronic devices), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and a portable compact disc read-only memory (CDROM). Furthermore, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or otherwise processing it in a suitable manner if necessary, and then storing it in a computer memory.

[0133] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiment, the N steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0134] Those skilled in the art will appreciate that all or part of the steps in the method for implementing the above-mentioned embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0135] In addition, the functional units in the various embodiments of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into a module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0136] The storage medium mentioned above may be a read-only memory, a magnetic disk, or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application. Persons skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A method for evaluating battery internal resistance consistency, characterized in that: The following steps are involved: Obtaining a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, a discharge current of the battery system, a third voltage of each battery cell before charge, a fourth voltage of each battery cell after charge, and a charge current of the battery system in a battery system at a target state of charge; Calculating the discharge internal resistance of each battery cell according to the first voltage of each battery cell before discharge, the second voltage of each battery cell after discharge, and the discharge current, and recording the maximum discharge internal resistance and the minimum discharge internal resistance of all battery cells to calculate the discharge internal resistance extreme value difference of each battery cell according to the maximum discharge internal resistance and the minimum discharge internal resistance; Calculating the charging internal resistance of each battery cell according to the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging, and the charging current, and recording the maximum charging internal resistance and the minimum charging internal resistance of all battery cells, so as to calculate the charging internal resistance extreme value difference of each battery cell according to the maximum charging internal resistance and the minimum charging internal resistance; Determine the discharge internal resistance target value of each battery cell and the charging internal resistance target value of each battery cell. If the discharge internal resistance extreme value difference is less than or equal to the discharge internal resistance target value, and the charging internal resistance extreme value difference is less than or equal to the charging internal resistance target value, then determine that the battery system meets the internal resistance consistency assessment.

2. The method according to claim 1, characterized in that The obtaining of a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, and a discharge current of the battery system in the battery system at a target state of charge includes: Based on the target ambient temperature, each of the battery cells is discharged at a first preset rate for a first time at a constant current, until the discharge satisfies a full-window discharge cutoff condition of each battery cell, and each of the battery cells is allowed to stand for a first time at the target ambient temperature, until each of the battery cells is allowed to stand to a preset ambient temperature; Performing a first constant current charge on each battery cell after the first rest at a second preset rate until the battery cell is charged to meet the first charging cutoff condition of the full window of each battery cell, switching to a third preset rate to perform a second constant current charge on each battery cell until the battery cell is charged to meet the second charging cutoff condition of the full window of each battery cell, and performing a second rest on each battery cell at the target ambient temperature until the battery cell is rested to the target ambient temperature; Based on the target ambient temperature, each battery cell is discharged at a fourth preset rate for a second constant current discharge to obtain a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, and a discharge current of the battery system.

3. The method according to claim 1, characterized in that The obtaining of a third voltage of each battery cell before charging, a fourth voltage of each battery cell after charging, and a charging current of the battery system in the battery system at a target state of charge includes: Allowing each battery cell to rest for a third time at the target ambient temperature, and after the resting time is set, replenishing current to each battery cell at a fifth preset rate until the replenished power of the battery system integrated with each battery cell is equal to the discharge capacity of the battery system; At the target ambient temperature, each battery cell is allowed to rest for a fourth time until each battery cell is allowed to rest to the target ambient temperature, and each battery cell is charged with a constant current for a third time at a sixth preset rate to obtain a third voltage of each battery cell in the battery system before charging, a fourth voltage of each battery cell after charging, and a charging current of the battery system.

4. The method according to claim 1, wherein The determining of the target discharge internal resistance value of each battery cell and the target charge internal resistance value of each battery cell includes: Obtain the DC internal resistance data of each battery cell when it is powered off; Extracting a first preset number of DC internal resistance data samples from the DC internal resistance data, and obtaining a second preset number of DC internal resistance data after extracting a preset number of times; obtaining the second preset number of discharge internal resistance extreme value differences and the second preset number of charge internal resistance extreme value differences based on the second preset number of DC internal resistance data; Calculate the sample mean and sample standard deviation of the DC internal resistance data sample based on a preset normal distribution strategy; According to the sample mean and the sample standard deviation, a preset distribution principle is used to obtain the discharge internal resistance variation range of each battery cell and the charging internal resistance variation range of each battery cell, and the upper limit value of the discharge internal resistance variation range is used as the discharge internal resistance target value, and the upper limit value of the charging internal resistance variation range is used as the charging internal resistance target value.

5. The method according to claim 1, wherein After determining the target discharge internal resistance value of each battery cell and the target charge internal resistance value of each battery cell, the method further includes: If the extreme difference in discharge internal resistance is greater than the target discharge internal resistance value, or the extreme difference in charge internal resistance is greater than the target charge internal resistance value, it is determined that the battery system does not meet the internal resistance consistency evaluation, and the battery cell with the smallest internal resistance in the battery system is replaced until the battery system meets the internal resistance consistency evaluation.

6. A device for evaluating battery internal resistance consistency, characterized in that: include: an acquisition module, configured to acquire a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, a discharge current of the battery system, a third voltage of each battery cell before charge, a fourth voltage of each battery cell after charge, and a charge current of the battery system in a battery system at a target state of charge; a first calculation module, configured to calculate a discharge internal resistance of each battery cell according to the first voltage of each battery cell before discharge, the second voltage of each battery cell after discharge, and the discharge current, and record a maximum discharge internal resistance and a minimum discharge internal resistance among all battery cells, so as to calculate a discharge internal resistance extreme value difference of each battery cell according to the maximum discharge internal resistance and the minimum discharge internal resistance; a second calculation module, configured to calculate a charging internal resistance of each battery cell according to the third voltage of each battery cell before charging, the fourth voltage of each battery cell after charging, and the charging current, and record a maximum charging internal resistance and a minimum charging internal resistance among all the battery cells, so as to calculate a charging internal resistance extreme value difference of each battery cell according to the maximum charging internal resistance and the minimum charging internal resistance; A determination module is configured to determine a target discharge internal resistance value for each battery cell and a target charge internal resistance value for each battery cell, and determine that the battery system satisfies an internal resistance consistency assessment if the extreme value difference in discharge internal resistance is less than or equal to the target discharge internal resistance value, and the extreme value difference in charge internal resistance is less than or equal to the target charge internal resistance value.

7. The device according to claim 6, characterized in that The acquisition module includes: a rest unit, configured to perform a first constant current discharge on each of the battery cells at a first preset rate based on a target ambient temperature until the discharge satisfies a full-window discharge cutoff condition of each battery cell, and to perform a first rest on each of the battery cells at the target ambient temperature until each of the battery cells is rested to a preset ambient temperature; a first charging unit, configured to perform a first constant current charging on each battery cell after the first rest at a second preset rate until the battery cell is charged to meet a first charging cutoff condition of the full window of each battery cell, switch to a third preset rate to perform a second constant current charging on each battery cell until the battery cell is charged to meet a second charging cutoff condition of the full window of each battery cell, and perform a second rest on each battery cell at the target ambient temperature until the battery cell is rested to the target ambient temperature; The discharge unit is used to perform a second constant current discharge on each battery cell at a fourth preset rate based on the target ambient temperature to obtain a first voltage of each battery cell before discharge, a second voltage of each battery cell after discharge, and a discharge current of the battery system.

8. The device according to claim 6, characterized in that The acquisition module includes: a current replenishing unit, configured to place each battery cell at a target ambient temperature for a third time, and after a preset resting time, replenish current to each battery cell at a fifth preset rate until the replenished power of the battery system integrated with each battery cell is equal to the discharge capacity of the battery system; The second charging unit is used to perform a fourth resting of each battery cell at the target ambient temperature until each battery cell is rested to the target ambient temperature, and perform a third constant current charging of each battery cell at a sixth preset rate to obtain a third voltage of each battery cell in the battery system before charging, a fourth voltage of each battery cell after charging, and a charging current of the battery system.

9. A vehicle, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for evaluating the consistency of internal resistance of a battery as claimed in any one of claims 1 to 5.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the method for evaluating battery internal resistance consistency as described in any one of claims 1 to 5.

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