Battery internal resistance detection method and device

Abstract

The invention relates to a battery internal resistance detection method and device. The method comprises the following steps: acquiring a pre-constructed association relationship based on temperature, current and internal resistance of a to-be-detected battery; in the charging process of the to-be-detected battery, when a preset condition is met, determining a first moment, and recording a charging parameter corresponding to the first moment; electric quantity integration is carried out at the first moment; in the discharging process of the to-be-detected battery, when the electric quantity integral reaches a preset threshold value, determining a second moment, and recording a discharging parameter corresponding to the second moment; and determining the internal resistance of the battery according to the charging parameter, the discharging parameter and the association relationship. According to the method, the dependence on the working condition environment, the data acquisition synchronism and the data acquisition frequency is reduced through the pre-constructed incidence relation of the temperature, the current and the internal resistance, the internal resistance of the battery is determined through the charging parameter, the discharging parameter and the incidence relation, and the detection precision of the internal resistance of the battery is further improved on the premise of not increasing extra cost.

Description

Technical Field

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

[0002] With the rapid development of new energy vehicles, portable electronic devices, and energy storage systems, lithium batteries have become the mainstream power source due to their high energy density, long cycle life, and environmentally friendly features. A battery's internal resistance refers to the resistance encountered by current flowing through the battery during operation. Internal resistance is a key parameter for measuring battery state of health (SOH) and energy efficiency, directly affecting the stability, power output capability, and cycle life of energy storage devices.

[0003] Current technologies typically use the DC internal resistance method or the AC impedance method to calculate battery internal resistance. However, because the current and voltage sensors are located on different chips, the two signals often experience a time offset, leading to inaccurate internal resistance calculations. The AC impedance method requires an electrochemical workstation or EIS chip to measure the impedance spectrum, adding additional costs. Summary of the Invention

[0004] Based on this, it is necessary to provide a battery internal resistance detection method and device to address the above technical issues.

[0005] In a first aspect, the present application provides a battery internal resistance detection method, the method comprising: obtaining a pre-constructed correlation relationship based on temperature, current and internal resistance of a battery to be detected; during the charging process of the battery to be detected, when a preset condition is met, determining a first moment and recording the charging parameters corresponding to the first moment; starting power integration at the first moment; during the discharging process of the battery to be detected, when the power integration reaches a preset threshold, determining a second moment and recording the discharge parameters corresponding to the second moment; determining the battery internal resistance based on the charging parameters, the discharge parameters and the correlation relationship.

[0006] In one embodiment, the method further includes: respectively obtaining the internal resistance of the test battery corresponding to multiple test conditions at a preset state of charge; the preset state of charge is a plateau state of charge; the test conditions include temperature and charge and discharge current; based on the internal resistance of the test battery corresponding to the standard condition, normalizing the internal resistance of the test battery corresponding to the multiple test conditions to obtain the internal resistance ratio corresponding to the multiple test conditions; and constructing a correlation relationship based on temperature, current and internal resistance of the battery to be tested according to the multiple test conditions and the internal resistance ratios corresponding to the multiple test conditions.

[0007] In one embodiment, the obtaining of multiple test conditions and the corresponding test battery internal resistance at the preset state of charge include: obtaining a first discharge voltage corresponding to the preset state of charge when the battery to be tested is discharged under the target test condition; the target test condition is any one of the multiple test conditions; obtaining a first charging voltage corresponding to the preset state of charge when the battery to be tested is charged under the target test condition; determining the first charging open-circuit voltage corresponding to the preset state of charge according to the preset state of charge and the state of charge-open-circuit voltage curve during charging; determining the first discharge open-circuit voltage corresponding to the preset state of charge according to the preset state of charge and the state of charge-open-circuit voltage curve during discharge; and determining the test battery internal resistance corresponding to the target test condition according to the first charging voltage, the first discharge voltage, the first charging open-circuit voltage, the first discharge open-circuit voltage and the charge and discharge current of the target test condition.

[0008] In one embodiment, during the charging process of the battery to be tested, when a preset condition is met, determining a first moment and recording the charging parameters corresponding to the first moment include: during the charging process of the battery to be tested, when a charging time condition, a charging temperature condition, and a charging state of charge condition are met, recording the current moment as the first moment; and obtaining the charging current, second charging voltage, charging state of charge, and charging temperature corresponding to the battery to be tested at the first moment.

[0009] In one embodiment, during the discharge process of the battery to be detected, when the power integral reaches a preset threshold, determining a second moment, and recording the discharge parameters corresponding to the second moment include: during the discharge process of the battery to be detected, when the power integral reaches a preset threshold, recording the current moment as the second moment; and obtaining the discharge current, second discharge voltage, discharge charge state, and discharge temperature corresponding to the battery to be detected at the second moment.

[0010] In one embodiment, determining the battery internal resistance based on the charging parameters, the discharging parameters, and the association includes: determining a fusion ratio based on the charging current, the charging temperature, the discharging current, the discharge temperature, and the association; determining an initial internal resistance based on the second charging voltage, the charging state of charge, the second discharging voltage, the discharging state of charge, and the fusion ratio; obtaining a filtering weight, and updating a pre-stored battery internal resistance based on the initial internal resistance and the filtering weight to obtain the battery internal resistance corresponding to the current moment.

[0011] In one embodiment, determining the fusion rate based on the charging current, charging temperature, discharging current, discharging temperature and the associated relationship includes: determining a first internal resistance rate based on the charging current, charging temperature and the associated relationship; determining a second internal resistance rate based on the discharging current, discharging temperature and the associated relationship; determining a fusion rate based on the charging current, discharging current, the first internal resistance rate and the second internal resistance rate.

[0012] In one embodiment, determining the initial internal resistance based on the second charging voltage, the charging state of charge, the second discharging voltage, the discharge state of charge, and the fusion rate includes: determining the average state of charge based on the charging state of charge and the discharge state of charge; determining the second charging open-circuit voltage and the second discharging open-circuit voltage corresponding to the average state of charge based on the average state of charge, the state of charge-open-circuit voltage curve during charging, and the state of charge-open-circuit voltage curve during discharging; determining the initial internal resistance based on the second charging voltage, the second discharging voltage, the second charging open-circuit voltage, the second discharge open-circuit voltage, and the fusion rate.

[0013] In one embodiment, the method further includes: constructing a data set based on the initial internal resistance and the charge and discharge parameters corresponding to the initial internal resistance; if the data set meets a preset data condition, updating the association relationship between temperature, current and internal resistance based on the data set.

[0014] In the second aspect, the present application also provides a battery internal resistance detection device, which includes: an acquisition module for obtaining a pre-constructed correlation relationship based on temperature, current and internal resistance of a battery to be detected; a first detection module for determining a first moment during the charging process of the battery to be detected when a preset condition is met, and recording the charging parameters corresponding to the first moment; an integration module for starting power integration at the first moment; a second detection module for determining a second moment during the discharging process of the battery to be detected when the power integration reaches a preset threshold, and recording the discharge parameters corresponding to the second moment; an internal resistance calculation module for determining the battery internal resistance based on the charging parameters, the discharge parameters and the correlation relationship.

[0015] In a third aspect, the present application further provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements any one of the battery internal resistance detection methods described in the first aspect when executing the computer program.

[0016] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any one of the battery internal resistance detection methods described in the first aspect.

[0017] The above-mentioned battery internal resistance detection method and device obtain a pre-constructed correlation relationship based on temperature, current and internal resistance. During the battery charging process, when the preset conditions are met, the first moment is determined and the charging parameters corresponding to the first moment are recorded. After determining the first moment, the power integration starts at the first moment. During the battery discharging process, when the power integration reaches a preset threshold, the second moment is determined and the discharge parameters corresponding to the second moment are recorded. Finally, the battery internal resistance is determined based on the charging parameters, discharge parameters and the correlation relationship. Through the pre-constructed correlation relationship between temperature, current and internal resistance, the dependence on the working environment, data acquisition synchronization and data acquisition frequency is reduced. The battery internal resistance is determined by the charging parameters, discharge parameters and the correlation relationship, and the detection accuracy of the battery internal resistance is further improved without adding additional costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a charge and discharge curve of a battery in one embodiment;

[0019] Figure 2 The internal resistance curve of the battery at 25 degrees in one embodiment;

[0020] Figure 3 1 is a flow chart of a method for detecting internal resistance of a battery in one embodiment;

[0021] Figure 4 A schematic flow chart of a method for establishing an association relationship in one embodiment;

[0022] Figure 5 1 is a flow chart of a method for calculating battery internal resistance in one embodiment;

[0023] Figure 6 1 is a flow chart of a method for calculating battery internal resistance using charge and discharge pairing in one embodiment;

[0024] Figure 7 This is a structural block diagram of a battery internal resistance detection device in one embodiment;

[0025] Figure 8 FIG. 1 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0027] With the rapid development of new energy vehicles, portable electronic devices, and energy storage systems, lithium batteries have become the mainstream power source due to their high energy density, long cycle life, and environmentally friendly features. A battery's internal resistance refers to the resistance encountered by current flowing through the battery during operation. Internal resistance is a key parameter for measuring battery state of health (SOH) and energy efficiency, directly affecting the stability, power output capability, and cycle life of energy storage devices. Battery internal resistance increases nonlinearly with capacity decay, temperature fluctuations, and changes in charge and discharge current. Traditional static internal resistance testing fails to reflect the dynamic characteristics under actual operating conditions.

[0028] In current related technologies, the battery internal resistance is usually calculated using a DC internal resistance method or an AC impedance method.

[0029] For the DC internal resistance method, the internal resistance value is calculated by selecting the instantaneous current fluctuation and obtaining the voltage drop and current change before and after the current fluctuation. The condition of this method must be the current change condition, and the current and voltage are synchronized, and the signal acquisition frequency is high. Because the current and voltage sensors are on different chips, there is often a time deviation between the two signals, which leads to inaccurate internal resistance calculation. For example, the cloud data has a data time deviation of about 10 seconds, so it is difficult to calculate the accurate internal resistance. The internal resistance during the plateau period is representative of the battery, but it is difficult to find a suitable plateau current fluctuation condition in the energy storage environment of peak shaving and valley filling.

[0030] For the AC impedance method, an AC signal of a certain frequency is applied and the impedance spectrum is measured using an electrochemical workstation or EIS chip. Among them, the EIS chip is a battery management chip that can evaluate the health status of the battery by monitoring the electrochemical impedance spectrum of the battery. The ohmic internal resistance and polarization internal resistance of the battery are obtained by measuring the impedance spectrum. This method can calculate the battery internal resistance at any time, but it requires additional costs, and most battery management systems do not have EIS functions.

[0031] Based on the above, the current related technologies have problems such as battery internal resistance, low detection accuracy, or the need to increase additional costs.

[0032] The internal resistance of a battery characterizes the battery status and aging. When the internal resistance of a battery changes, it indicates that an abnormality may occur inside the battery and an alarm needs to be issued for maintenance. However, the actual situation is that the internal resistance of the battery is affected by temperature, current, and state of charge. When a change in internal resistance is detected, there is a high probability that it is caused by temperature, current, and state of charge, which will lead to abnormal false alarms. Therefore, an embodiment of the present application provides a low-cost, high-precision, and normalized internal resistance calculation method suitable for various scenarios. The internal resistance calculated by this method has high accuracy, and through normalization processing, it can avoid the influence of temperature, current, and state of charge, and further accurately detect battery abnormalities through internal resistance.

[0033] In the embodiment of the present application, the calculation of the internal resistance is based on the charge and discharge plateau period. Figure 1 As shown, Figure 1 is the charge and discharge curve of the battery. Figure 1 The blue curve in the figure is the state of charge-open circuit voltage curve during battery charging, also known as the SOC-OCV curve during charging. The battery model for the constant current charging process is: V charging voltage = chgOcv + I charging current * R(I, T), where V charging voltage is the charging voltage during constant current charging, I charging current is the charging current during constant current charging, chgOcv is the open circuit voltage during constant current charging, and R(I, T) is the battery internal resistance when the charging voltage is I and the charging temperature is T during constant current charging. Figure 1 The red curve in the figure is the state of charge-open circuit voltage curve during battery discharge, that is, the SOC-OCV curve during discharge. The battery model of the constant current discharge process is: V discharge voltage = disOcv + I discharge current * R(I, T), where V discharge voltage is the discharge voltage during constant current discharge, I discharge current is the discharge current during constant current discharge, disOcv is the open circuit voltage during constant current discharge, and R(I, T) is the battery internal resistance when the discharge voltage is I and the discharge temperature is T during constant current discharge. Based on Figure 1 The battery has a plateau during the charge and discharge process. During this plateau period (SOC = 20% ~ 90%), the voltage basically does not change, that is, the voltage does not change significantly with SOC. The relationship between the battery's OCV and SOC is stable and is less affected by temperature and aging. The battery's internal resistance is affected by temperature and rate, but during the plateau period (SOC = 20% ~ 90%), the internal resistance is close to the same, such as Figure 2 As shown, Figure 2 The internal resistance curve of the battery at 25 degrees is based on Figure 2 During the plateau period, internal resistance changes little. Therefore, through testing, we establish a correlation between the battery's internal resistance at different temperatures and currents. Based on this, we can calculate the battery's internal resistance using the charging voltage, current, and discharging voltage and current at the same SOC. This process is suitable for most energy storage scenarios.

[0034] In one embodiment, Figure 3 As shown, a battery internal resistance detection method is provided, comprising the following steps:

[0035] Step 301: Obtain a pre-built correlation relationship based on temperature, current and internal resistance of a battery to be tested.

[0036] Before calculating the internal resistance of a battery to be tested, the battery to be tested needs to be tested and a correlation relationship based on temperature, current, and internal resistance of the battery to be tested needs to be established. The battery to be tested is the battery for which the internal resistance calculation is required. For example, when testing the battery to be tested, the battery to be tested is charged and discharged separately under different test conditions, and the charging and discharging parameters during the charging and discharging process are recorded. The test conditions include temperature and charge and discharge current. Using the charging and discharge parameters corresponding to each test condition, the internal resistance of the test battery corresponding to the test condition is calculated, that is, the internal resistance of the test battery corresponding to the temperature and charge and discharge current is obtained. Using the internal resistances of the test batteries corresponding to multiple groups of different test conditions, a correlation relationship based on temperature, current, and internal resistance is established. The correlation relationship can be a mapping relationship table in tabular form, or a functional relationship based on temperature, current, and internal resistance can be obtained by function fitting. This is not specifically limited in this embodiment, and the correlation relationship only needs to be able to express the corresponding relationship between temperature, current, and internal resistance. After the battery to be tested is tested and the correlation relationship is obtained, the correlation relationship is stored. When the internal resistance of the battery is actually calculated, the correlation relationship corresponding to the battery to be tested is obtained from the memory.

[0037] Step 302 : During the charging process of the battery to be tested, when a preset condition is met, a first moment is determined, and charging parameters corresponding to the first moment are recorded.

[0038] When calculating the internal resistance of a battery to be tested, the first moment at which preset conditions are met is determined during the charging process of the battery to be tested, and the charging parameters corresponding to the first moment are recorded. The charging parameters include charging temperature, charging current, charging voltage, and charging state of charge. The charging temperature is the charging temperature at the first moment, the charging current is the charging current at the first moment, the charging voltage is the charging voltage at the first moment, and the charging state of charge is the charging state at the first moment. The state of charge is also the remaining charge percentage. The preset conditions include charging time, charging temperature, and charging state of charge.

[0039] Step 303: Start electricity integration at the first moment.

[0040] After the first moment is determined, the electric quantity integration is performed starting from the first moment. For example, starting from the first moment, the charging current or the discharging current is acquired in real time, and the electric quantity integration is performed based on the charging current or the discharging current.

[0041] Step 304 : During the discharge process of the battery to be tested, when the power integral reaches a preset threshold, a second moment is determined, and a discharge parameter corresponding to the second moment is recorded.

[0042] Starting from the first moment, the power integration is performed until the power integration reaches a preset threshold value during the discharge process of the battery to be tested, the moment when the preset threshold value is reached is determined to be the second moment, and the discharge parameters corresponding to the second moment are recorded. The preset threshold value can be 0. When the power integration is 0, it means that from the first moment to the second moment, the charging power is equal to the discharging power, that is, the state of charge at the first moment is the same as the state of charge at the second moment. Preferably, the preset threshold value can be set as a redundant value. The preset threshold value of the example can be 5% of the nominal capacity of the battery to be tested. The discharge parameters include discharge temperature, discharge current, discharge voltage and discharge charge state. The discharge temperature is the discharge temperature at the second moment, the discharge current is the discharge current at the second moment, the discharge voltage is the discharge voltage at the second moment, and the discharge charge state is the charge state at the second moment.

[0043] Step 305 : determining the battery internal resistance according to the charging parameters, the discharging parameters, and the correlation relationship.

[0044] After obtaining the paired charging and discharging parameters, the battery internal resistance is determined through a pre-established correlation relationship based on temperature, current, and internal resistance.

[0045] In this embodiment, by obtaining a pre-constructed correlation relationship based on temperature, current and internal resistance, during the battery charging process, when the preset conditions are met, the first moment is determined and the charging parameters corresponding to the first moment are recorded. After determining the first moment, the power integration starts at the first moment. During the battery discharging process, when the power integration reaches a preset threshold, the second moment is determined and the discharge parameters corresponding to the second moment are recorded. Finally, the battery internal resistance is determined based on the charging parameters, discharge parameters and the correlation relationship. Through the pre-constructed correlation relationship between temperature, current and internal resistance, the dependence on the working environment, data acquisition synchronization and data acquisition frequency is reduced. The battery internal resistance is determined by the charging parameters, discharge parameters and the correlation relationship, and the detection accuracy of the battery internal resistance is further improved without increasing additional costs.

[0046] In one embodiment, Figure 4 As shown, a method for establishing an association relationship is provided, which specifically includes the following steps:

[0047] Step 401 : obtaining the internal resistance of the test battery corresponding to a plurality of test conditions at a preset state of charge.

[0048] First, multiple test conditions are constructed. The battery to be tested is then tested under each test condition to obtain the internal resistance of the test battery. The test conditions include temperature and charge / discharge current. Multiple test conditions refer to conditions with different temperatures and charge / discharge currents. For example, the test condition can be: 25°C, 0.3°C. Alternatively, it can be 30°C, 0.6°C. This embodiment does not specifically limit the test conditions' temperature and charge / discharge current; multiple test conditions can be obtained by simply varying the temperature and charge / discharge current. Where C represents the rate, 1C represents a current value of 1 multiplied by the battery's nominal capacity, and 0.3C represents a current value of 0.3 multiplied by the battery's nominal capacity. After obtaining multiple test conditions, for each test condition, the charge and discharge parameters corresponding to the same preset state of charge are obtained. The internal resistance of the test battery corresponding to the corresponding test condition is then determined based on the charge and discharge parameters. The preset state of charge is a plateau state of charge. For example, the preset state of charge can range from 40% to 85%, and preferably, the preset state of charge can be 80%.

[0049] In one embodiment, calculating the internal resistance of the test battery includes the following steps:

[0050] Step 1: Obtain a first discharge voltage corresponding to a preset state of charge when discharging the battery under test under a target test condition.

[0051] The target test condition is any one of a variety of test conditions. This description will be made using the target test condition of 25 degrees Celsius and 0.3C, with a preset state of charge of 80%. First, it is necessary to obtain the state-of-charge-open-circuit voltage curve of the battery under test during charging and the state-of-charge-open-circuit voltage curve during discharge, namely the charging SOC-OCV curve and the discharging SOC-OCV curve. These curves can be obtained from the manufacturer of the battery under test, or by performing a conventional pulse test on the battery under test; this is not specifically limited in this embodiment.

[0052] First, at 25°C, charge the battery to 90% SOC at a current of 0.3C. Then, at 25°C and a current of 0.3C, discharge the battery to 20% of its nominal capacity, effectively discharging it to 70% SOC. During the discharge process, calculate the SOC at each moment and obtain the first discharge voltage corresponding to SOC = 80%. This first discharge voltage is the discharge voltage at which the battery reaches 80% SOC during the discharge process.

[0053] Step 2: Obtain a first charging voltage corresponding to a preset state of charge when charging the battery to be tested under a target test condition.

[0054] After discharging the battery under test, it is then charged to 20% of its nominal capacity at a temperature of 25°C and a current of 0.3°C, effectively charging it to a SOC of 90%. During the charging process, the SOC is calculated at each moment, and the first charging voltage corresponding to an SOC of 80% is obtained. This first charging voltage is the charging voltage at which the battery under test reaches a SOC of 80% during the charging process.

[0055] Step 3: Determine a first charging open circuit voltage corresponding to the preset state of charge according to the preset state of charge and a state of charge-open circuit voltage curve during charging.

[0056] After obtaining the first charging voltage, a first charging open-circuit voltage corresponding to the preset state of charge is calculated based on the preset state of charge and the state of charge-open-circuit voltage curve during charging. The first charging open-circuit voltage is the open-circuit voltage when the state of charge of the battery to be tested is 80% during charging.

[0057] Step 4: Determine a first discharge open circuit voltage corresponding to the preset state of charge according to the preset state of charge and a state of charge-open circuit voltage curve during discharge.

[0058] After obtaining the first discharge voltage, a first discharge open-circuit voltage corresponding to the preset state of charge is calculated based on the preset state of charge and the state of charge-open-circuit voltage curve during discharge. The first discharge open-circuit voltage is the open-circuit voltage when the state of charge of the battery to be tested is 80% during discharge.

[0059] Step 5: Determine the internal resistance of the test battery corresponding to the target test condition according to the first charging voltage, the first discharging voltage, the first charging open-circuit voltage, the first discharging open-circuit voltage, and the charge and discharge current of the target test condition.

[0060] The specific calculation formula is as follows:

[0061]

[0062] Among them, chgVol 80 Indicates the first charging voltage, disVol 80 Indicates the first discharge voltage, chgOcv 80 Indicates the first charging open circuit voltage, disOcv 80 represents the first discharge open circuit voltage, I represents the charge and discharge current of the target test condition, and R 测试 Indicates the internal resistance of the test battery corresponding to the target test condition.

[0063] Based on the above test method, the internal resistance of the test battery is calculated for each test condition, and the internal resistance of the test battery corresponding to the multiple test conditions is obtained.

[0064] Step 402 : Taking the internal resistance of the test battery corresponding to the standard working condition as a reference, normalize the internal resistance of the test battery corresponding to the various test working conditions to obtain the internal resistance ratios corresponding to the various test working conditions.

[0065] After obtaining the internal resistance of the test battery corresponding to a variety of test conditions, it is necessary to determine the standard operating condition among the multiple test conditions. For example, a temperature of 25 degrees and a charge and discharge current of 0.3C can be determined as the standard operating condition. After determining the standard operating condition, the internal resistance of the test battery corresponding to the standard operating condition is used as a benchmark to normalize the internal resistance of the test battery corresponding to all test conditions to obtain the internal resistance ratio corresponding to each test condition. Specifically, the internal resistance of the test battery corresponding to all test conditions is divided by the internal resistance of the test battery corresponding to the standard operating condition to obtain the internal resistance ratio corresponding to each test condition. It can be understood that the internal resistance ratio corresponding to the standard operating condition is 1.

[0066] Step 403 : constructing a correlation relationship based on temperature, current, and internal resistance of the battery to be tested according to the multiple test conditions and the internal resistance ratios corresponding to the multiple test conditions.

[0067] After calculating the internal resistance ratios corresponding to various test conditions, each test condition including temperature, charge / discharge current, and internal resistance ratio, a correlation between temperature, current, and internal resistance is determined based on the temperature, charge / discharge current, and internal resistance ratio corresponding to each test condition.

[0068] In one embodiment, a mapping relationship table can be constructed based on multiple test conditions and the internal resistance ratios corresponding to the multiple test conditions.

[0069] Temperature\Current 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 10 1.66 1.51 1.37 1.32 1.26 1.21 1.17 1.12 1.07 1.03 15 1.49 1.36 1.23 1.19 1.14 1.09 1.05 1.01 0.97 0.93 20 1.34 1.22 1.11 1.07 1.02 0.98 0.94 0.91 0.87 0.83 25 1.21 1.1 1.00 0.96 0.92 0.88 0.85 0.82 0.78 0.75 30 1.09 0.99 0.90 0.86 0.83 0.80 0.76 0.73 0.70 0.68 35 0.98 0.89 0.81 0.78 0.75 0.72 0.69 0.66 0.63 0.61 40 0.88 0.80 0.73 0.70 0.67 0.64 0.62 0.59 0.57 0.55 45 0.79 0.72 0.66 0.63 0.60 0.58 0.56 0.53 0.51 0.49

[0070] The first row shows the charge and discharge current, ranging from 0.1C to 1C. The first column shows the temperature, ranging from 10°C to 45°C. The parameters in the table are the internal resistance ratios corresponding to the temperature and charge and discharge current. It should be understood that the temperature and charge and discharge current values in the above table are only examples. In actual use, more test conditions can be constructed.

[0071] In one embodiment, a functional relationship can be constructed based on multiple test conditions and the internal resistance ratios corresponding to the multiple test conditions. Because batteries age, the relationship between their internal resistance, temperature, and current will also change. Therefore, it is necessary to continuously update the association relationship. It is difficult to update a simple table. Therefore, the association relationship can be expressed by constructing a function relationship. The specific functional relationship is:

[0072] rate=F(T,Ic)=a*exp(b*(T-25)+c*(Ic-0.3))

[0073] Where rate is the internal resistance ratio, T is the temperature, and Ic is the charge and discharge current. a, b, and c are function coefficients, obtained by fitting various test conditions and the corresponding internal resistance ratios. In the above functional relationship, rate = 1 under standard operating conditions. Based on the above, the internal resistance ratio decreases with increasing temperature while the charge current remains unchanged, and decreases with increasing charge and discharge current while the temperature remains unchanged.

[0074] This embodiment constructs a correlation by testing the battery under test under various test conditions. This pre-established correlation between temperature, current, and internal resistance reduces dependence on operating conditions, data acquisition synchronization, and data acquisition frequency when calculating internal resistance, further improving the accuracy of battery internal resistance calculations.

[0075] In one embodiment, during the charging process of the battery to be tested, when a preset condition is met, a first moment is determined, and recording the charging parameters corresponding to the first moment specifically includes: during the charging process of the battery to be tested, when a charging time condition, a charging temperature condition, and a charging state of charge condition are met, recording the current moment as the first moment; and obtaining the charging current, second charging voltage, charging state of charge, and charging temperature corresponding to the battery to be tested at the first moment.

[0076] The charging time condition may be that the charging time is greater than a preset time threshold, the charging temperature condition may be that the charging temperature is greater than a preset temperature threshold, and the charging state of charge condition may be that the current state of charge is within a preset state of charge range. This embodiment does not specifically limit the preset time threshold, preset temperature threshold, and preset state of charge range, and they can be set according to actual usage. For example, the preset time threshold may be 2-30 minutes, the preset temperature threshold may be 10 degrees, and the preset state of charge range may be 40%-80%. It is understandable that during the charging process of the battery to be tested, when the charging time reaches the preset time threshold, the charging temperature is greater than the preset temperature threshold, and the current state of charge is within the preset state of charge range, the current moment is recorded as the first moment. The charging current, second charging voltage, charging state of charge, and charging temperature of the battery to be tested at the first moment are obtained.

[0077] In one embodiment, during the discharge process of the battery to be tested, when the power integral reaches a preset threshold, determining a second moment, and recording the discharge parameters corresponding to the second moment specifically include: during the discharge process of the battery to be tested, when the power integral reaches a preset threshold, recording the current moment as the second moment; obtaining the discharge current, second discharge voltage, discharge charge state and discharge temperature corresponding to the battery to be tested at the second moment.

[0078] After the first moment is determined, the charge integration will be performed starting from the first moment. That is, starting from the first moment, the charging current or the discharging current is obtained in real time, and the charge integration is performed using the charging current or the discharging current. During the discharge process of the battery to be tested, when the charge integration reaches the preset threshold, the current moment is recorded as the second moment. And the discharge current, the second discharge voltage, the discharge charge state and the discharge temperature of the battery to be tested at the second moment are obtained. Among them, the preset threshold can be 0. When the charge integration is 0, it means that from the first moment to the second moment, the charge state is equal to the discharge state, that is, the charge state at the first moment is the same as the charge state at the second moment. Preferably, the preset threshold can be set as a redundant value. The preset threshold in the example can be 5% of the nominal capacity of the battery to be tested.

[0079] In this embodiment, the charging parameters and the discharging parameters are paired by integrating the charge quantity, that is, the state of charge at the first moment is the same as the state of charge at the second moment. Based on the charging parameters and the discharging parameters at the same state of charge, the calculation accuracy of the battery internal resistance can be improved.

[0080] In one embodiment, Figure 5 As shown, a method for calculating the internal resistance of a battery is provided, which specifically includes the following steps:

[0081] Step 501 : determining a fusion rate according to the charging current, charging temperature, discharging current, discharging temperature and their correlation.

[0082] After obtaining the charging parameters and discharging parameters, the fusion ratio is determined according to the charging current, charging temperature, discharging current, discharging temperature and the correlation. Specifically, first, the first internal resistance ratio is determined according to the charging current, charging temperature and the correlation. That is, the charging current and charging temperature are substituted into the above functional relationship, and the first internal resistance ratio corresponding to the charging current and charging temperature is calculated. Then, the second internal resistance ratio is determined according to the discharge current, discharge temperature and the correlation. That is, the discharge current and discharge temperature are substituted into the above functional relationship, and the second internal resistance ratio corresponding to the discharge current and discharge temperature is calculated. Finally, the fusion ratio is determined according to the charging current, discharge current, the first internal resistance ratio and the second internal resistance ratio. The specific calculation formula is:

[0083] mixI=w dis ·|disI|+w chg ·|chgI|

[0084] Among them, mixI is the fusion ratio, w dis is the second internal resistance ratio, disI is the discharge current, w chg is the first internal resistance ratio, chgI is the charging current.

[0085] Step 502 : determining an initial internal resistance according to the second charging voltage, the charging state of charge, the second discharging voltage, the discharging state of charge, and the fusion rate.

[0086] First, determine the average state of charge based on the charging state of charge and the discharging state of charge. The specific formula is as follows:

[0087]

[0088] Among them, chgSoc is the charging state of charge, disSoc is the discharging state of charge, and avgSoc is the average state of charge.

[0089] Then, based on the average state of charge, the state of charge-open circuit voltage curve during charging, and the state of charge-open circuit voltage curve during discharging, a second charge open circuit voltage and a second discharge open circuit voltage corresponding to the average state of charge are determined. Specifically, the second charge open circuit voltage corresponding to the average state of charge is calculated based on the average state of charge and the state of charge-open circuit voltage curve during charging. The second discharge open circuit voltage corresponding to the average state of charge is calculated based on the average state of charge and the state of charge-open circuit voltage curve during discharging.

[0090] Finally, the initial internal resistance is determined based on the second charging voltage, the second discharging voltage, the second charging open-circuit voltage, the second discharging open-circuit voltage, and the fusion rate. The specific formula is as follows:

[0091]

[0092] Among them, chgVol is the second charging voltage, disVol is the second discharging voltage, chgOcv soc The second charging open circuit voltage, disOcv soc is the second discharge open circuit voltage, mixI is the fusion rate, and Ri is the initial internal resistance.

[0093] Step 503 : Obtain a filtering weight, and based on the initial internal resistance and the filtering weight, update the pre-stored battery internal resistance to obtain the battery internal resistance corresponding to the current moment.

[0094] After the initial internal resistance is calculated, there will be accidental errors each time the internal resistance is calculated, so it is necessary to eliminate the accidental errors through filtering. The specific formula is as follows:

[0095] batR 新 =batR 旧 *w+(1-w)*R i

[0096] Among them, batR 新 batR is the battery internal resistance corresponding to the current moment after update. 旧is the pre-stored battery internal resistance, w is the filter weight, and Ri is the initial internal resistance. The filter weight is generally set between 0.5 and 1. This embodiment of the application does not impose any specific restrictions and is set based on actual usage requirements. The pre-stored battery internal resistance is the updated battery internal resistance from the last calculation of the battery internal resistance.

[0097] In this embodiment, the fusion rate is determined by the charging parameters and the discharging parameters, and the battery internal resistance is determined based on the fusion rate, thereby further improving the calculation accuracy of the battery internal resistance.

[0098] In one embodiment, after calculating the battery internal resistance, a pre-established association relationship can be updated based on the real-time calculated battery internal resistance and the corresponding charge and discharge parameters. This includes: constructing a data set based on the initial internal resistance and the charge and discharge parameters corresponding to the initial internal resistance; and, if the data set meets pre-set data conditions, updating the association relationship based on temperature, current, and internal resistance based on the data set.

[0099] After calculating the battery internal resistance, the charging parameters corresponding to the first moment of the charging process, the discharge parameters corresponding to the second moment of the discharging process, and the battery internal resistance can be stored to build a database. For example, the average temperature of the charging and discharging temperatures is calculated, and the average current of the charging and discharging currents is calculated. The average current, average temperature, and battery internal resistance are correlated to build a database. When the amount of data in the database reaches a certain amount, the correlation between temperature, current, and internal resistance is updated based on the data set.

[0100] In one specific embodiment, Figure 6 As shown, a method for calculating the internal resistance of a battery using charge and discharge pairing is provided, which specifically includes the following steps:

[0101] Step 1: Obtain the charging SOC-OCV curve and the discharging SOC-OCV curve from the battery manufacturer, or obtain the charging SOC-OCV curve and the discharging SOC-OCV curve through a conventional pulse test.

[0102] Step 2: Using 25 degrees Celsius and 0.3C as standard operating conditions, establish the relationship between the battery plateau period, different temperatures, different currents, and internal resistance. Where C represents the rate, and 1C means current value = 1 * battery nominal capacity.

[0103] Step 2.1: Charge the battery to SOC = 90% at a current of I = 0.3C at 25 degrees Celsius.

[0104] Step 2.2: discharge 20% of the battery's nominal capacity at a temperature of T = 25 degrees and a current of I = 0.3C, that is, discharge the battery to a SOC of 70%.

[0105] Step 2.3: charge the battery to 20% of its nominal capacity at a temperature of T = 25 degrees and a current of I = 0.3C, that is, charge the battery to SOC = 90%.

[0106] Step 2.4: Select the discharge data in step 2.2, calculate the SOC value at each moment, and record the discharge voltage when SOC = 80%, which is recorded as disVol 80 Select the charging data in step 2.3, calculate the SOC value at each moment, and record the charging voltage when SOC = 80%, recorded as chgVol 80 . According to the discharge voltage at SOC = 80% and the discharge SOC-OCV curve, determine the discharge open circuit voltage at SOC = 80%. According to the charge voltage at SOC = 80% and the charge SOC-OCV curve, determine the charge open circuit voltage at SOC = 80%. Calculate the internal resistance as shown below:

[0107]

[0108] chgVol 80 Indicates the charging voltage when SOC=80%, disVol 80 Indicates the discharge voltage when SOC=80%, chgOcv 80 Indicates the charging open circuit voltage when SOC=80%, disOcv 80 Indicates the discharge open circuit voltage when SOC=80%, R 测试 represents the internal resistance, and I represents the charge and discharge current.

[0109] Step 2.5, adjust the temperature T and current I. For example, the temperature T can be modified to 10, 15, 20, ... 45 degrees in sequence; the current I can be modified to 0.1, 0.2, ... 1C in sequence. Repeat steps 2.1-2.4 with the modified temperature and current to obtain the internal resistance values corresponding to different temperatures and currents. Then take the internal resistance corresponding to the standard working condition of 25 degrees and 0.3C as the standard internal resistance for normalization. Calculate the ratio of the internal resistance value to the standard internal resistance at other temperatures and currents to obtain the internal resistance correlation table for different temperatures and currents. The format is shown in the following table,

[0110] Temperature\Current 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 10 1.66 1.51 1.37 1.32 1.26 1.21 1.17 1.12 1.07 1.03 15 1.49 1.36 1.23 1.19 1.14 1.09 1.05 1.01 0.97 0.93 20 1.34 1.22 1.11 1.07 1.02 0.98 0.94 0.91 0.87 0.83 25 1.21 1.1 1.00 0.96 0.92 0.88 0.85 0.82 0.78 0.75 30 1.09 0.99 0.90 0.86 0.83 0.80 0.76 0.73 0.70 0.68 35 0.98 0.89 0.81 0.78 0.75 0.72 0.69 0.66 0.63 0.61 40 0.88 0.80 0.73 0.70 0.67 0.64 0.62 0.59 0.57 0.55 45 0.79 0.72 0.66 0.63 0.60 0.58 0.56 0.53 0.51 0.49

[0111] In step 2.6, as batteries age, the relationship between their internal resistance, temperature, and current will also change. Therefore, it is necessary to continuously update the parameter table relationship. It is difficult to update a simple table, so we can update the relationship by constructing a relationship. The constructor is as follows:

[0112] rate=F(T,Ic)=a*exp(b*(T-25)+c*(Ic-0.3))

[0113] Among them, T is the temperature, Ic is the charge and discharge current, and rate is the ratio of the internal resistance value at the current temperature and current to the standard internal resistance. a, b, and c are function coefficients, which are obtained by fitting all the data in the above table. When the above exponential formula is under standard working conditions, rate = 1. And the internal resistance ratio decreases with the increase of temperature when the charging current remains unchanged, and the internal resistance ratio decreases with the increase of the charge and discharge current when the temperature remains unchanged. On the contrary, it increases.

[0114] Step 3: Calculate the internal resistance by the charge and discharge pairing method during the real-time operation process.

[0115] Step 3.1: During real-time operation, during the battery charging process, select any moment that satisfies the constant current or constant power charging time is greater than m minutes, the temperature is greater than n degrees, and 80% < SOC < 40%, and record it as t chg . And record t chg The charging current at time t is chgI, the charging voltage is chgVol, the charging SOC is chgSoc, and the charging temperature is chgTemp. Among them, the value of m is related to the battery characteristics and can be set to 2 - 30 minutes. By setting the continuous charging time, the influence brought by polarization can be eliminated. n can be set to the minimum temperature in Step 2.5, and for example, it can be set to be greater than or equal to 10 degrees.

[0116] Step 3.2: Starting from time t chg , continuously accumulate the electric quantity Q according to the ampere-hour integration formula, and the formula is as follows:

[0117]

[0118] In the formula, the charging current is positive and the discharging current is negative.

[0119] Step 3.3: During the battery discharging process, select any moment when |Q| < 0.5% of the nominal capacity, and record it as t dis . And record t dis The discharging current at time t is disI, the discharging voltage is disVol, the discharging SOC is disSoc, and the discharging temperature is disTemp. Through the limitation of Q, the SOC at time t chg and time t dis are equal. At this time, a set of charging data and discharging data under the same SOC can be obtained.

[0120] Calculate the average SOC:

[0121]

[0122] Among them, chgSoc is the charging SOC, disSoc is the discharging SOC, and avgSoc is the average SOC.

[0123] Calculate the fusion ratio:

[0124] mixI=w dis ·|disI|+w chg ·|chgI|

[0125] Substituting the discharge current disI and the discharge temperature disTemp into the formula F(T,Ic), we can get w dis , where w dis Substituting the charging current chgI and the charging temperature chgTemp into the formula F(T,Ic), we get w chg , where w chg is the second ratio. mixI is the fusion ratio.

[0126] According to the average SOC and charging SOC-OCV curve, the open circuit voltage chgOcv is calculated soc According to the average SOC and discharge SOC-OCV curve, the open circuit voltage disOcv is calculated. soc .

[0127] Using data from different currents and temperatures, calculate the internal resistance at 25 degrees and 0.3°C. The formula is as follows:

[0128]

[0129] Record the disI, disVol, disSoc, chgI, chgVol, chgSoc, and Ri of the successful pairing to establish an internal resistance calculation database.

[0130] In step 3.4, since there will be accidental errors each time the internal resistance is calculated, it is necessary to eliminate the accidental errors through filtering. The specific formula is as follows:

[0131] barR 新 =batR 旧 *w+(1-w)*R i

[0132] Among them, batR 新 batR is the battery internal resistance corresponding to the current moment after update. 旧 is the pre-stored battery internal resistance, w is the filter weight, and Ri is the internal resistance calculated in step 3.3. The filter weight is generally set between 0.5 and 1.

[0133] Step 4: During real-time operation, collect the internal resistance calculated after charge and discharge pairing and the corresponding charge and discharge data, and update the function constructed in step 2.6.

[0134] Step 4.1, when the amount of data in the internal resistance calculation database in step 3.3 reaches a certain amount, update the function constructed in step 2.6. Because the Ri calculated in steps 3.1-3.3 uses a ratio calculation formula to equate the internal resistance at different temperatures and different currents to the internal resistance under standard working conditions, if the ratio calculation formula is accurate, then the calculated series of Ri should be relatively close. If the ratio calculation formula is inaccurate, then the series of Ri will have a large difference. Therefore, the parameters of the ratio calculation formula can be updated based on the difference in a series of internal resistances in the internal resistance calculation database. Specifically, the ion cluster algorithm is used to update the optimization formula parameters, with the minimum standard deviation of a series of internal resistances in the internal resistance calculation database as the optimization goal, and the formula parameters are continuously adjusted.

[0135] In step 4.2, set the update range of a, b, and c, adjust the values of a, b, and c, and then recalculate the internal resistance based on the new formula using the data in the internal resistance calculation database to calculate the standard deviation of a series of internal resistances.

[0136] In step 4.3, use the particle swarm algorithm to continuously adjust the values of a, b, and c, iterate n times, and when n>3, output a, b, and c with the smallest internal resistance standard deviation and update the formula.

[0137] The embodiment of the present application can calculate the resistance of the battery without detecting current fluctuations or additional equipment, and is particularly suitable for calculating internal resistance in energy storage scenarios.

[0138] Peak shaving and valley filling is a common application scenario for energy storage. Traditional methods make it difficult to calculate the battery's internal resistance during plateau periods. This embodiment of the present application establishes an internal resistance prediction function by coupling characteristic parameters of the charge and discharge curves, reducing dependence on operating conditions, data acquisition synchronization, and data acquisition frequency. This method is particularly suitable for calculating battery internal resistance in peak shaving and valley filling scenarios.

[0139] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0140] Based on the same inventive concept, embodiments of the present application also provide a battery internal resistance detection device for implementing the aforementioned battery internal resistance detection method. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more battery internal resistance detection device embodiments provided below can be found in the above-described limitations of the battery internal resistance detection method and will not be further elaborated here.

[0141] In one embodiment, Figure 7 As shown, a battery internal resistance detection device is provided, including: an acquisition module 100, a first detection module 200, an integration module 300, a second detection module 400 and an internal resistance calculation module 500, wherein:

[0142] An acquisition module 100 is configured to acquire a pre-established correlation relationship based on temperature, current, and internal resistance of a battery to be tested;

[0143] The first detection module 200 is configured to determine a first moment and record charging parameters corresponding to the first moment when a preset condition is met during the charging process of the battery to be detected;

[0144] An integration module 300 is configured to start integrating electric quantity at a first moment;

[0145] The second detection module 400 is configured to determine a second moment when the integrated charge reaches a preset threshold value during the discharge process of the battery to be detected, and record the discharge parameters corresponding to the second moment;

[0146] The internal resistance calculation module 500 is configured to determine the battery internal resistance according to the charging parameter, the discharging parameter, and the correlation relationship.

[0147] The acquisition module 100 is further used to respectively obtain the internal resistance of the test battery corresponding to multiple test conditions at a preset state of charge; the preset state of charge is a plateau state of charge; the test conditions include temperature and charge and discharge current; based on the internal resistance of the test battery corresponding to the standard condition, the internal resistance of the test battery corresponding to the multiple test conditions is normalized to obtain the internal resistance ratio corresponding to the multiple test conditions; based on the multiple test conditions and the internal resistance ratios corresponding to the multiple test conditions, a correlation relationship based on temperature, current and internal resistance of the battery to be tested is constructed.

[0148] The acquisition module 100 is further used to obtain a first discharge voltage corresponding to the preset state of charge when the battery to be tested is discharged under a target test condition; the target test condition is any one of a plurality of test conditions; obtain a first charging voltage corresponding to the preset state of charge when the battery to be tested is charged under the target test condition; determine the first charging open-circuit voltage corresponding to the preset state of charge based on the preset state of charge and the state of charge-open-circuit voltage curve during charging; determine the first discharge open-circuit voltage corresponding to the preset state of charge based on the preset state of charge and the state of charge-open-circuit voltage curve during discharge; determine the internal resistance of the test battery corresponding to the target test condition based on the first charging voltage, the first discharge voltage, the first charging open-circuit voltage, the first discharge open-circuit voltage and the charge and discharge current of the target test condition.

[0149] The first detection module 200 is further configured to, during the charging process of the battery to be detected, record the current moment as the first moment when the charging time condition, the charging temperature condition, and the charging state of charge condition are met; and obtain the charging current, the second charging voltage, the charging state of charge, and the charging temperature corresponding to the battery to be detected at the first moment.

[0150] The second detection module 400 is further configured to, during the discharge process of the battery to be detected, when the power integral reaches a preset threshold, record the current moment as a second moment; and obtain the discharge current, second discharge voltage, discharge charge state, and discharge temperature corresponding to the battery to be detected at the second moment.

[0151] The internal resistance calculation module 500 is further used to determine the fusion ratio based on the charging current, charging temperature, discharging current, discharging temperature and their associated relationships; determine the initial internal resistance based on the second charging voltage, charging state of charge, second discharging voltage, discharging state of charge and fusion ratio; obtain the filtering weight, and update the pre-stored battery internal resistance based on the initial internal resistance and the filtering weight to obtain the battery internal resistance corresponding to the current moment.

[0152] The internal resistance calculation module 500 is further used to determine a first internal resistance ratio based on the charging current, charging temperature and the associated relationship; determine a second internal resistance ratio based on the discharge current, discharge temperature and the associated relationship; and determine a fusion ratio based on the charging current, discharge current, the first internal resistance ratio and the second internal resistance ratio.

[0153] The internal resistance calculation module 500 is further used to determine the average state of charge based on the charging state of charge and the discharging state of charge; determine the second charging open-circuit voltage and the second discharging open-circuit voltage corresponding to the average state of charge based on the average state of charge, the state of charge-open-circuit voltage curve during charging, and the state of charge-open-circuit voltage curve during discharging; and determine the initial internal resistance based on the second charging voltage, the second discharging voltage, the second charging open-circuit voltage, the second discharging open-circuit voltage, and the fusion rate.

[0154] The internal resistance calculation module 500 is further configured to construct a data set based on the initial internal resistance and the charge and discharge parameters corresponding to the initial internal resistance; and update the correlation between temperature, current and internal resistance based on the data set if the data set meets a preset data condition.

[0155] Each module in the battery internal resistance detection device described above can be implemented in whole or in part through software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in hardware form, or can be stored in a computer device memory in software form, so that the processor can call and execute the corresponding operations of each module.

[0156] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as follows: Figure 8 As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a battery internal resistance detection method is implemented.

[0157] Those skilled in the art will understand that Figure 8 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0158] In one embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements any one of the battery internal resistance detection methods in the above embodiments when executing the computer program.

[0159] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, any one of the battery internal resistance detection methods in the above embodiments is implemented.

[0160] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processor involved in the various embodiments provided herein may be, but are not limited to, a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic unit, a data processing logic unit based on quantum computing, and the like.

[0161] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0162] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A battery internal resistance detection method, characterized in that: The method comprises: Obtain a pre-built correlation relationship based on temperature, current and internal resistance of the battery to be tested; During the charging process of the battery to be tested, when a preset condition is met, determining a first moment and recording a charging parameter corresponding to the first moment; Starting to perform power integration at the first moment; During the discharge process of the battery to be tested, when the power integral reaches a preset threshold, determining a second moment and recording the discharge parameters corresponding to the second moment; The internal resistance of the battery is determined according to the charging parameter, the discharging parameter, and the association relationship.

2. The method according to claim 1, characterized in that The method further comprises: Obtaining multiple test conditions and corresponding test battery internal resistance at a preset state of charge; the preset state of charge is a plateau state of charge; the test conditions include temperature and charge and discharge current; Taking the internal resistance of the test battery corresponding to the standard working condition as a benchmark, the internal resistance of the test battery corresponding to various test working conditions is normalized to obtain the internal resistance ratio corresponding to the various test working conditions; According to the multiple test conditions and the internal resistance ratios corresponding to the multiple test conditions, a correlation relationship based on temperature, current and internal resistance of the battery to be tested is constructed.

3. The method according to claim 2, characterized in that The multiple test conditions are obtained respectively, and the corresponding test battery internal resistance at the preset state of charge includes: Obtaining a first discharge voltage corresponding to the preset state of charge when discharging the battery to be tested under a target test condition; the target test condition is any one of multiple test conditions; Obtaining a first charging voltage corresponding to the preset state of charge when the battery to be tested is charged under a target test condition; Determining a first charging open circuit voltage corresponding to the preset state of charge according to the preset state of charge and a state of charge-open circuit voltage curve during charging; Determining a first discharge open-circuit voltage corresponding to the preset state of charge according to the preset state of charge and a state of charge-open-circuit voltage curve during discharge; An internal resistance of a test battery corresponding to the target test condition is determined according to the first charging voltage, the first discharging voltage, the first charging open-circuit voltage, the first discharging open-circuit voltage, and the charging and discharging current of the target test condition.

4. The method according to claim 1, wherein During the charging process of the battery to be tested, when a preset condition is met, determining a first moment and recording a charging parameter corresponding to the first moment includes: During the charging process of the battery to be tested, when a charging time condition, a charging temperature condition, and a charging state of charge condition are met, recording the current moment as the first moment; Obtaining a charging current, a second charging voltage, a charging state of charge, and a charging temperature corresponding to the battery to be detected at the first moment.

5. The method according to claim 4, characterized in that During the discharge process of the battery to be tested, when the power integral reaches a preset threshold, determining a second moment and recording the discharge parameter corresponding to the second moment includes: During the discharge process of the battery to be tested, when the power integral reaches a preset threshold, the current moment is recorded as the second moment; Obtain a discharge current, a second discharge voltage, a discharge state, and a discharge temperature corresponding to the battery to be detected at the second moment.

6. The method according to claim 5, characterized in that The determining the battery internal resistance according to the charging parameter, the discharging parameter, and the association relationship includes: Determining a fusion rate according to the charging current, charging temperature, discharging current, discharging temperature and their associated relationships; determining an initial internal resistance according to the second charging voltage, the charging state of charge, the second discharging voltage, the discharging state of charge, and the fusion rate; A filtering weight is obtained, and based on the initial internal resistance and the filtering weight, a pre-stored battery internal resistance is updated to obtain the battery internal resistance corresponding to the current moment.

7. The method according to claim 6, characterized in that The determining of the fusion rate according to the charging current, charging temperature, discharging current, discharging temperature and the associated relationship includes: Determining a first internal resistance ratio according to the charging current, the charging temperature, and the associated relationship; determining a second internal resistance ratio according to the discharge current, the discharge temperature, and the associated relationship; A fusion ratio is determined according to the charging current, the discharging current, the first internal resistance ratio, and the second internal resistance ratio.

8. The method according to claim 6, characterized in that The determining of the initial internal resistance according to the second charging voltage, the charging state of charge, the second discharging voltage, the discharging state of charge, and the fusion rate includes: determining an average state of charge based on the charging state of charge and the discharging state of charge; Determining a second charging open-circuit voltage and a second discharging open-circuit voltage corresponding to the average state of charge according to the average state of charge, a state of charge-open-circuit voltage curve during charging, and a state of charge-open-circuit voltage curve during discharging; An initial internal resistance is determined according to the second charging voltage, the second discharging voltage, the second charging open-circuit voltage, the second discharging open-circuit voltage, and the fusion rate.

9. The method according to claim 6, characterized in that The method further comprises: constructing a data set according to the initial internal resistance and the charge and discharge parameters corresponding to the initial internal resistance; If the data set meets the preset data condition, the association relationship between temperature, current and internal resistance is updated based on the data set.

10. A battery internal resistance detection device, characterized in that: The device comprises: An acquisition module is used to obtain a pre-built correlation relationship based on temperature, current and internal resistance of the battery to be tested; A first detection module is configured to determine a first moment and record charging parameters corresponding to the first moment when a preset condition is met during the charging process of the battery to be detected; An integration module, used for starting power integration at the first moment; A second detection module is configured to determine a second moment when the integrated charge reaches a preset threshold value during the discharge process of the battery to be detected, and record the discharge parameters corresponding to the second moment; The internal resistance calculation module is used to determine the internal resistance of the battery according to the charging parameter, the discharging parameter and the correlation relationship.

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