WO2023082046A1

WO2023082046A1 - Method for determining direct-current discharge resistance, method for determining maximum discharge power, and battery management system

Info

Publication number: WO2023082046A1
Application number: PCT/CN2021/129543
Authority: WO
Inventors: 王丹凤; 宋晋阳
Original assignee: 宁德时代新能源科技股份有限公司
Priority date: 2021-11-09
Filing date: 2021-11-09
Publication date: 2023-05-19
Also published as: CN116685853A

Abstract

The present application relates to a method for determining the direct-current discharge resistance of a battery. The method comprises: acquiring working condition data of a battery within a specified state-of-health interval, wherein the working condition data comprises the temperature, state of charge, current and voltage of the battery, and the specified state-of-health interval is the state-of-health interval corresponding to the latest state-of-health point, which has been passed and is specified for updating a data table of direct-current discharge resistance; determining a data table of direct-current discharge resistance of the battery within the specified state-of-health interval according to the working condition data of the battery within the specified state-of-health interval; acquiring the current temperature and the current state of charge of the battery; and determining the direct-current discharge resistance of the battery according to the data table of the direct-current discharge resistance within the specified state-of-health interval, the current temperature and the current state of charge. The present application further relates to a method for determining the maximum discharge power of a battery, and a battery management system.

Description

Method for determining DC discharge resistance and maximum discharge power and battery management system

technical field

The present application relates to the field of battery technology, and in particular to a method for determining a DC discharge resistance of a battery, a method for determining a maximum discharge power of a battery, and a battery management system.

Background technique

With the development of new energy technology, more and more fields use batteries as power. Due to the advantages of high energy density, rechargeable, safe and environmentally friendly, batteries are widely used in new energy vehicles, consumer electronics, energy storage systems and other fields.

The power supply capacity of the battery directly affects the performance of the electrical equipment. In order to maximize the performance of the battery and protect the battery from being discharged, it is necessary to estimate the maximum available power of the battery.

Contents of the invention

In view of the above problems, the present application proposes a method for determining the DC discharge resistance of a battery, a method for determining the maximum discharge power of a battery, and a battery management system.

To this end, a first aspect of the present invention provides a method for determining the DC discharge resistance of a battery, wherein the method comprises:

Obtain the working condition data of the battery in the specified health state interval, the working condition data includes the temperature, charge state, current, voltage and health state of the battery, and the above specified health state interval is the one that has been experienced and is designated for updating the DC discharge resistance The health status interval corresponding to the latest health status point in the data table;

Determine the data table of the DC discharge resistance of the battery in the above-mentioned designated health state interval according to the working condition data of the battery in the above-mentioned designated health state interval;

Obtain the current temperature and current state of charge of the battery; and

Determine the DC discharge resistance of the battery from the data sheet for DC discharge resistance within the specified state of health interval above, as well as the current temperature and current state of charge.

In the embodiment of the present application, the DC discharge resistance of the battery is determined by obtaining the data table of the DC discharge resistance in the latest health state interval, and according to the data table of the DC discharge resistance, the current temperature and the state of charge. This embodiment obtains the data table of the DC discharge resistance during the whole life cycle of the battery, thereby ensuring the accuracy of the determined DC discharge resistance.

In the embodiments of the present application, "DC discharge resistance" refers to the resistance of the battery during DC discharge, rather than the static internal resistance of the battery.

In some embodiments of the present application, the data table for determining the DC discharge resistance of the battery within the above specified state of health interval includes:

Filter out the data fragments that meet the preset working condition conditions from the working condition data in the above-mentioned specified health state interval;

When the current of a data point in the data segment is within the preset current interval, it is updated according to the mutuality between the data of the data point and the data of the corresponding position of the data point in the discharge current and voltage difference data table Data sheets for discharge current and voltage difference;

When the data at the corresponding position satisfies the preset sufficient condition, calculate the DC discharge resistance of the battery at the corresponding position according to the linear fitting relationship between the discharge current and the voltage difference; and

According to whether the calculated working conditions covered by the DC discharge resistance meet the preset data adequacy conditions and the health status of the data point, the data table of the DC discharge resistance of the battery within the specified health status interval is completed.

In the embodiment of the present application, "corresponding position" refers to the corresponding table position of the state of charge (SOC) and temperature of the data point in the data table of discharge current and voltage difference. In the embodiment of the present application, by updating the two-dimensional data table of discharge current and voltage difference based on temperature and state of charge, and regularly updating the data table of DC discharge resistance, the data in the data table of DC discharge resistance of the battery is ensured The current parameter situation closest to the battery.

In some embodiments of the present application, the above-mentioned preset working conditions include a static period and a pulse period, the static period requires a current rate less than or equal to 0.05C and the duration is greater than or equal to 30 seconds, and the pulse period requires an average current rate Greater than or equal to 0.2C, state of charge greater than or equal to 30% and duration greater than or equal to 2 seconds. In some embodiments of the present application, after determining that the working condition data meets the requirements of the static period, it is then determined whether the working condition data meets the requirements of the pulse period.

When measuring the data sheet of the DC discharge resistance under different SOC and temperature offline, it is necessary to let the battery stand for a period of time, then discharge it at a constant current for a period of time, and then measure the resistance between the end of the resting period and the end of the constant current discharge. Voltage difference, and use the voltage difference and constant current discharge current to measure the DC discharge resistance. However, under the actual operating conditions of electrical equipment such as electric vehicles, it is almost impossible to have the static and constant current conditions of offline measurement, so the working conditions are relaxed to the above-mentioned static segment and pulse segment requirements to screen the available The data.

In some embodiments of the present application, determining the data table of the DC discharge resistance of the battery within the above specified health state range includes the following steps:

When the current in the pulse segment of the data segment does not meet the quasi-constant current condition, the current in the pulse segment of the data segment is converted into an equivalent constant current. In some embodiments of the present application, the quasi-constant current condition is that the current fluctuates no more than ±7%, preferably ±5%. The lower the current fluctuation in the quasi-constant current condition, the more accurate the data obtained; however, when the current fluctuation is too low, there will not be enough data to meet the requirements of the preset working conditions. Therefore, the application is implemented in the most preferred In the scheme, the quasi-constant current condition was set as ±5%.

In the embodiment of this application, the current of the pulse segment may appear in the following situations: monotonically increasing, monotonically decreasing, constant current or quasi-constant current, first monotonically increasing and then constant current or quasi-constant current, first monotonically decreasing and then constant current or Quasi-constant current, etc. After converting the non-constant current into an equivalent constant current, the equivalent constant current can be used to calculate the DC discharge resistance.

In some embodiments of the present application, the equivalent constant current is calculated according to the following formulas (1) and (2):

Among them, I _eq represents the equivalent constant current, w(t) represents the weight function, I(t) represents the discharge current at the sampling time point, t _end represents the end time of the pulse segment, n is a positive integer and 2≤n≤6 .

In some embodiments of the present application, the above preset current intervals include three current intervals, the first current interval of the three current intervals is between 0.05 and 0.2 times the maximum discharge current, and the three current intervals are between 0.05 and 0.2 times the maximum discharge current. The second current interval is between 0.2 times and 0.4 times of the above-mentioned maximum discharge current, and the third current interval among the three current intervals is between 0.4 and 0.8 times of the above-mentioned maximum discharge current, and the above-mentioned maximum discharge current has a rated capacity The maximum current allowed for the battery to be discharged at the temperature and state of charge corresponding to the working condition of the data point. In the embodiment of the present application, as described before, it is necessary to judge whether the current of the data points in the data segment is within a plurality of preset current intervals, to ensure that the data of the discharge current and the voltage difference are within the linear range, and it is hoped that The current is distributed in each current interval to obtain a more usable linear fitting curve.

In some embodiments of the present application, when the capacity of the battery at the data point has decayed by a preset percentage relative to the rated capacity of the battery, the data table of the discharge current and the voltage difference is cleared or a new data table is provided to store the discharge current and Voltage difference data. In some embodiments of the present application, whenever the capacity of the battery decays by 5%, a new two-dimensional data table of discharge current and voltage difference based on temperature and state of charge is stored, and the data table of DC discharge resistance is updated. In this embodiment, the capacity decay of the battery by 5% represents a large change in the internal parameters of the battery, so the new discharge current and voltage difference are used to calculate the DC discharge resistance that also undergoes a large change. In the implementation of clearing the two-dimensional data table of discharge current and voltage difference, clearing the two-dimensional data table of discharge current and voltage difference is based on the consideration of saving system memory or limited system memory. When the system memory is sufficient or the system memory is not considered , you can keep all the original two-dimensional data tables of discharge current and voltage difference and use the new two-dimensional data table to store the data of discharge current and voltage difference.

In some embodiments of the present application, determining the data table of the DC discharge resistance of the battery within the above-mentioned specified health state interval comprises the following steps:

When the data of the data point is not different from the data of the corresponding position:

Take the average value of the voltage difference between the voltage at the end of the rest period in the data segment and the voltage of the data point and the voltage difference between the corresponding position and the data of the data point without mutuality to replace the corresponding position and the data The data of the point does not have the voltage difference of the data of mutuality; and

The current of the data point and the current of the data having no dissimilarity between the corresponding position and the data of the data point are averaged to replace the current of the data having no dissimilarity between the corresponding position and the data of the data point.

In this embodiment, when there is no mutuality, the voltage difference and current are averaged, so that the data at the corresponding position is updated closer to the actual value, reducing the error.

When the data of the data point is different from the data of the corresponding position, the data table of the discharge current and the voltage difference is updated according to the relationship between the data of the data point and the data of the corresponding position in the above-mentioned preset current interval, Wherein the above-mentioned preset current range includes a plurality of current ranges.

In this embodiment, the two-dimensional data table of discharge current and voltage difference is updated according to the relationship between the data of the data point and the data of the corresponding position in the preset multiple current intervals, and the data stored in the discharge current and voltage difference can be controlled. The distribution of the data in the two-dimensional data table makes the availability of the linear fitting curve of the discharge current and the voltage difference higher.

In some embodiments of the present application, the criterion for judging that the data of the data point has mutual dissimilarity with the data of the corresponding position is that the current of the data point is relative to the data in the two-dimensional data table of the discharge current and the voltage difference. The temperature of the point fluctuates within 1° C. and the state of charge fluctuates within 2 percent, and the current fluctuates more than 5 percent.

In the embodiment of the present application, updating the two-dimensional data table of discharge current and voltage difference based on temperature and state of charge hopes to fill each cell in the two-dimensional data table, but the measured data cannot be completely corresponding Based on the SOC and temperature point of the table position in the two-dimensional data table, it is necessary to judge which cell of the two-dimensional data table the measurement data falls in according to the mutuality judgment standard. If there is data stored in the grid where the measurement data falls, it is considered to have no mutuality, and if there is no data stored in the grid where the measurement data falls, it is considered to have mutuality.

In some embodiments of the present application, the step of updating the data table of the discharge current and the voltage difference according to the relationship between the data of the data point and the data of the corresponding position within the above-mentioned preset current interval includes:

When the data at the corresponding position is distributed in the above-mentioned multiple current intervals, compare the data of the corresponding position before and after the data of the current interval where the data point in the corresponding position is replaced with the data of the data point. The square of the correlation coefficient of the voltage difference linear fit;

When the square of the correlation coefficient using the data of the data point is larger, the data of the data point is stored in the data table of the discharge current and the voltage difference.

In the embodiment of the present application, by retaining data with a larger square of the correlation coefficient, the error of the linear fitting of the voltage difference and the current is smaller. In some embodiments of the present application, the correlation coefficient R can be calculated according to the following formula (3):

Among them, Cov(X, Y) is the covariance of X and Y, Var[X] is the variance of X, Var[Y] is the variance of Y, and the range of R is -1～+1. Therefore, the square of the correlation coefficient can be expressed by the following formula (4):

in,

is the mean of X,

is the mean of Y. In an embodiment of the present application, X corresponds to the current value and Y corresponds to the voltage difference.

When the data at the corresponding position is not distributed in the above-mentioned multiple current intervals, it is judged whether the data at the corresponding position has a value in the current interval where the current of the data point is located;

When the data at the corresponding position has no value in the current interval where the current of the data point is located, the data of the data point is stored in the data table of discharge current and voltage difference.

When the data at the corresponding position has a value in the current interval where the current of the data point is located, determine whether the data of the data point is credible; and

When the data for this data point is credible:

When the current of the data point is in the current interval with the smallest current value among the above-mentioned multiple current intervals, the current of the data point and the current at the corresponding position in the current interval with the smallest current value among the above-mentioned multiple current intervals are smaller The data of current value is saved in the data table of discharge current and voltage difference;

When the current of the data point is not in the current interval with the smallest current value among the above-mentioned multiple current intervals, the current of the data point and the current at the corresponding position in the current interval where the current of the data point is located is the larger current value The data is saved in the data table for discharge current and voltage difference.

In some embodiments of the present application, the above-mentioned preset current intervals include three current intervals, the first current interval of the above-mentioned three current intervals is between 0.05 times and 0.2 times of the maximum discharge current, and the above-mentioned three current intervals The second current interval in the above-mentioned three current intervals is between 0.2 times and 0.4 times of the above-mentioned maximum discharge current, and the third current interval among the above-mentioned three current intervals is between 0.4 times and 0.8 times of the above-mentioned maximum discharge current, and the above-mentioned maximum discharge current is The maximum current allowed for a battery with rated capacity to be discharged at the temperature and state of charge corresponding to the working condition of the data point;

When the data for this data point is credible:

When the current of the data point is in the first current interval, the current of the data point and the data of the smaller current value in the current of the corresponding position in the first current interval are stored in the data table of discharge current and voltage difference;

When the current of the data point is in the second current interval or the third current interval, the data of the larger current value among the current of the data point and the current of the corresponding position in the current interval where the current of the data point is located is stored in data sheet for discharge current and dropout voltage.

In the embodiment of the present application, by judging whether the data is credible, it is ensured that the data conforms to the change rule, and the situation of skipping points in the data table is avoided. In addition, by retaining a smaller current in the first current interval and a larger current in the second current interval and the third current interval, the currents are closer to the two ends and the distribution is more uniform, so that a more usable linearity can be obtained Curve fitting.

In the specific implementation of this application, the principles for judging the credibility of data points include:

When the current of the data point is greater than the current of the data at the corresponding position in the current interval of the current of the data point, the voltage difference of the data point is greater than the voltage of the data of the corresponding position in the current interval of the current of the data point poor; and

The resistance of the data point fluctuates by no more than 20% of the resistance of the current interval where the current of the data point is located relative to the data at the corresponding position, wherein the resistance of the data point is equal to the voltage difference of the data point divided by the current, and the The resistance of the data at the corresponding position in the current interval of the current of the data point is equal to the voltage difference of the data of the corresponding position in the current interval of the current of the data point divided by the current.

Based on the consideration of system memory, in a preferred embodiment of the present application, the working condition data of the battery is the working condition data of the two battery cells with the lowest state of charge and voltage in the battery. However, it should be understood that when the system memory is not considered, the working condition data of the battery may include not only two representative cells, but also all the cells in the battery.

In some embodiments of the present application, the voltage difference of the data point is equal to the voltage at the end of the rest period in the data segment minus the voltage of the data point; and

The current at this data point is the absolute value of the discharge current of the battery.

In the embodiment of the present application, since the filtered data segments are being discharged, the voltage of the battery keeps decreasing, so the voltage difference of the data points is a positive value. In addition, although in the battery management system (BMS), the symbol of the charging current is +, and the symbol of the discharging current is -; however, in the embodiment of the present application, the absolute value of the discharging current is taken as the current value of the data point, that is, stored in The current values in the data sheets of the discharge current and the voltage difference are both positive values, and the currents compared with each other are all positive values. Therefore, both the current value and the voltage difference used in the calculation of the above formulas (3) and (4) are positive values.

In some embodiments of the present application, the above preset current range includes multiple current ranges, and the preset sufficient conditions include:

The data of the corresponding position in the data table of discharge current and voltage difference are distributed in the above-mentioned multiple current intervals; and

The square of the correlation coefficient of the linear fitting of the discharge current and the voltage difference at the corresponding position in the data table of the discharge current and the voltage difference is greater than or equal to 0.95.

In the embodiment of the present application, through the preset sufficient conditions, it is ensured that the current and voltage difference data used to calculate the DC discharge resistance are grouped, linear fitting can be performed, and the error of the linear fitting is small enough.

In other embodiments of the present application, the preset sufficient conditions include:

The minimum current at the corresponding position in the discharge current and voltage difference data table is between 0.05 and 0.2 times the maximum discharge current at the corresponding position;

The current change step at the corresponding position in the data table of discharge current and voltage difference is between 0.15 times and 0.3 times the maximum discharge current at the corresponding position; and

The square of the correlation coefficient of the linear fitting of the current and voltage difference at the corresponding position in the data table of the discharge current and voltage difference is greater than or equal to 0.95;

Wherein the maximum discharge current at the corresponding position is the maximum current allowed to be discharged by a battery with rated capacity at the temperature and state of charge of the corresponding position.

In some embodiments of the present application, the step of calculating the DC discharge resistance of the battery at the corresponding position according to the linear fitting relationship between the discharge current and the voltage difference includes:

Linear fitting is performed on the discharge current and the voltage difference at the corresponding position to obtain the slope and pitch of the fitted voltage difference-current curve;

According to the state of charge-open circuit voltage curve of the battery and the state of charge of the corresponding position, the open circuit voltage of the corresponding position is obtained;

Subtracting the cut-off voltage of the battery from the open circuit voltage at the corresponding position to obtain the first maximum voltage difference at the corresponding position;

Obtaining the first maximum discharge current according to the above-mentioned fitted voltage difference-current curve and the above-mentioned first maximum voltage difference;

Selecting the minimum value of the above-mentioned first maximum discharge current and the second maximum discharge current as the third maximum discharge current, wherein the above-mentioned second maximum discharge current is the discharge current limited by the mechanical parts of the battery;

Obtaining a second maximum voltage difference according to the above-mentioned fitted voltage difference-current curve and the above-mentioned third maximum discharge current; and

Divide the second maximum voltage difference by the third maximum discharge current to obtain the DC discharge resistance of the battery at the corresponding position.

In an embodiment of the present application, the first maximum voltage difference ΔU _max is calculated according to the following formula (5):

ΔU _max = OCV-U _cutoff (5)

Wherein, OCV is the open circuit voltage of the corresponding position, and _Ucutoff is the cutoff voltage of the battery. Then, the first maximum current corresponding to the first maximum voltage difference ΔU _max is determined according to the fitted voltage difference-current curve obtained when the discharge current and the voltage difference are linearly fitted or when the correlation coefficient of the linear fit is calculated before. I _max0 :

Wherein, k is the slope of the fitted voltage difference-current curve, and b is the pitch of the fitted voltage difference-current curve. Since the maximum discharge current allowed by the battery is not only limited by the cut-off voltage, but also limited by mechanical parts, the actual maximum discharge current allowed by the battery is determined according to the following formula (7):

I' _max = min(I _max0 , I _max1 ) (7)

Wherein, I' _max is the maximum discharge current allowed by the battery actually, that is, the third maximum discharge current; I _max1 is the maximum discharge current limited by the cut-off voltage, that is, the second maximum discharge current. After determining the actual maximum discharge current _I'max allowed by the battery, according to the fitted voltage difference-current curve obtained when the discharge current and the voltage difference are linearly fitted or when the correlation coefficient of the linear fit is calculated before, determine The maximum voltage difference corresponding to I' _max , that is, the second maximum voltage difference ΔU′ _max :

ΔU' _max =k*I' _max +b (8).

Finally, calculate the DC discharge resistance DCR according to the following formula (9):

DCR = _ΔU'max / _I'max (9).

In some embodiments of the present application, when the working conditions covered by the calculated DC discharge resistance meet the preset data sufficiency conditions, the discharge current and voltage difference are completed according to the existing data in the data table of the discharge current and voltage difference The data table, and based on the data in the completed discharge current and voltage difference data table, complete the data table of the DC discharge resistance of the battery in the above-mentioned specified health state interval according to the linear fitting relationship between the discharge current and the voltage difference.

In some embodiments of the present application, the preset data sufficiency conditions include that the calculated operating conditions covered by the DC discharge resistance meet the following requirements:

Covered temperatures include at least three sets of temperatures between -20 and 25°C, each of the at least three sets of temperatures separated by greater than or equal to 10°C;

The covered temperatures include at least two sets of temperatures between 25 and 55°C, each of the at least two sets of temperatures separated by greater than or equal to 10°C; and

The covered states of charge include at least two groups of states of charge between 30% and 100%, and the interval between each group of states of charge in the at least two groups of states of charge is greater than or equal to 20%.

In the embodiment of the present application, through the preset data adequacy condition, it is ensured that the data stored in the data table of the discharge current and the voltage difference is sufficient, so that the data of the discharge current and the voltage difference can be completed by methods such as linear interpolation. All data in the data table.

In some embodiments of the present application, the step of completing the data table of the discharge current and the voltage difference according to the existing data in the data table of the discharge current and the voltage difference includes:

Carry out linear fitting on the current and voltage difference of the existing temperature and state of charge, and complement the voltage difference in the above preset current range of the existing temperature and state of charge according to the fitted ΔU-I curve;

performing linear interpolation for the voltage difference between 30% and 100% of the state of charge to complement the voltage difference between 30% and 100% of the state of charge based on the voltage difference of the known temperature, state of charge and current; and

According to the voltage difference of known temperature, state of charge and current, perform linear fitting on lnΔU and 1/T, where the unit of T is Kelvin, and interpolate according to the fitted lnΔU-1/T curve at -25 to 25°C and the voltage difference between 25 to 55°C.

When the working conditions covered by the calculated DC discharge resistance do not meet the preset data sufficiency conditions, it is judged whether the capacity of the battery at the data point has decayed by a preset percentage relative to the rated capacity of the battery;

When the capacity of the battery at this data point has decayed by a preset percentage relative to the rated capacity of the battery, the maximum growth rate of the DC discharge resistance calculated at the same temperature relative to the DC discharge resistance in the data sheet of the previous DC discharge resistance , calculate the DC discharge resistance of the missing state of charge to complement the DC discharge resistance of different temperatures and states of charge.

In the implementation of this application, when the data is not enough, it is judged whether the capacity of the battery has attenuated the percentage of forced update, if the preset percentage has not decayed, then continue to supplement the data; if the preset percentage has decayed, follow the growth law Supplementary data. This implementation scheme ensures that the data conforms to the changing law and avoids jumping points in the data table.

A second aspect of the present application provides a battery management system, wherein the battery management system is configured to determine the DC discharge resistance of the battery, and the battery management system includes:

at least one processor; and

a memory connected to at least one of the processors;

Wherein the memory stores instructions, and when the instructions are executed by the at least one processor, the instructions cause the at least one processor to execute the method for determining the DC discharge resistance of the battery described in the first aspect above.

A third aspect of the present application provides a method for determining the maximum discharge power of a battery, wherein the method includes:

Obtain the working condition data of the battery in the specified health state interval, the working condition data includes the battery temperature, state of charge, current, voltage and health state, and the above specified health state interval is the one that has been experienced and is designated for updating the maximum discharge power The health status interval corresponding to the latest health status point in the data table;

According to the working condition data of the battery in the above-mentioned designated health state interval, determine the data table of the maximum discharge power of the battery in the above-mentioned designated health state interval;

Obtain the current temperature and current state of charge of the battery; and

Determine the maximum discharge power of the battery according to the data table of the maximum discharge power within the above specified health state interval, as well as the current temperature and the current state of charge.

In the embodiment of the present application, the maximum discharge power of the battery is determined by obtaining the data table of the maximum discharge power of the latest health state interval, and according to the data table of the maximum discharge power, the current temperature and the state of charge. This implementation obtains the data table of the maximum discharge power during the entire life cycle of the battery, and can calculate the DC discharge resistance and maximum discharge power of the battery according to the real-time working conditions during the entire life cycle, thereby ensuring the accuracy of the determined maximum discharge power. The performance of the battery can be maximized, and the safety and power of driving can be improved at the same time.

In some embodiments of the present application, the data table for determining the maximum discharge power of the battery within the above specified health state range includes:

Filter out the data fragments that meet the preset working condition conditions from the working condition data within the specified health state interval;

When the data at the corresponding position satisfies the preset sufficient condition, calculate the maximum discharge power of the battery at the corresponding position according to the linear fitting relationship between the discharge current and the voltage difference; and

According to whether the working condition covered by the calculated maximum discharge power satisfies the preset data adequacy condition and the health state of the data point, the data table of the maximum discharge power of the battery within the specified health state interval is completed.

In the embodiment of the present application, by updating the two-dimensional data table of discharge current and voltage difference based on temperature and state of charge, the data table of the maximum discharge power is regularly updated, ensuring the data in the data table of the maximum discharge power of the battery The current parameter condition closest to the battery.

In some embodiments of the present application, determining the data table of the maximum discharge power of the battery within the specified health state interval includes the following steps:

When the current in the pulse segment of the data segment does not meet the quasi-constant current condition, the current in the pulse segment of the data segment is converted into an equivalent constant current. In some embodiments of the present application, the quasi-constant current condition is that the current fluctuates no more than ±7%, preferably ±5%. The lower the current fluctuation in the quasi-constant current condition, the more accurate the data obtained; however, when the current fluctuation is too low, there will not be enough data to meet the requirements of the preset working conditions. Therefore, in the embodiment of the present application, the limit of the current fluctuation under the quasi-constant current condition will not be lower than ±2%; in the most preferred embodiment, the quasi-constant current condition is set to ±5%.

In the embodiment of this application, the current of the pulse segment may appear in the following situations: monotonically increasing, monotonically decreasing, constant current or quasi-constant current, first monotonically increasing and then constant current or quasi-constant current, first monotonically decreasing and then constant current or Quasi-constant current, etc. After converting the non-constant current into an equivalent constant current, the equivalent constant current can be used to calculate the maximum discharge power.

In some embodiments of the present application, the equivalent constant current is calculated according to the above formulas (1) and (2).

In some embodiments of the present application, when the capacity of the battery at the data point has decayed by a preset percentage relative to the rated capacity of the battery, the data table of the discharge current and the voltage difference is cleared or a new data table is provided to store the discharge current and the voltage difference. Voltage difference data. In some embodiments of the present application, whenever the capacity of the battery declines by 5%, a new two-dimensional data table of discharge current and voltage difference based on temperature and state of charge is stored, and the data table of maximum discharge power is updated. In this embodiment, the capacity decay of the battery by 5% means that the internal parameters of the battery have changed greatly, so the new discharge current and voltage difference are used to calculate the maximum discharge power that also changes greatly. In the implementation of clearing the two-dimensional data table of discharge current and voltage difference, clearing the two-dimensional data table of discharge current and voltage difference is based on the consideration of saving system memory or limited system memory. When the system memory is sufficient or the system memory is not considered , you can keep all the original two-dimensional data tables of discharge current and voltage difference and use the new two-dimensional data table to store the data of discharge current and voltage difference.

In the embodiment of the present application, by retaining data with a larger square of the correlation coefficient, the error of the linear fitting of the voltage difference and the current is smaller. In some embodiments of the present application, the correlation coefficient R can be calculated according to the above formula (3), and the square of the correlation coefficient can be expressed by the above formula (4).

When the data for this data point is credible:

In the embodiment of the present application, since the filtered data segments are being discharged, the voltage of the battery keeps decreasing, so the voltage difference of the data points is a positive value. In addition, although in the battery management system (BMS), the symbol of the charging current is +, and the symbol of the discharging current is -; however, in the embodiment of the present application, the absolute value of the discharging current is taken as the current value of the data point, that is, stored in The current values in the data sheets of the discharge current and the voltage difference are both positive values, and the currents compared with each other are all positive values.

In the embodiment of the present application, through the preset sufficient conditions, it is ensured that the current and voltage difference data used to calculate the maximum discharge power are grouped, linear fitting can be performed, and the error of the linear fitting is small enough.

The current change step of the corresponding position in the data table of the discharge current and the voltage difference is between 0.15 times and 0.3 times of the maximum discharge current at the corresponding position; and

In some embodiments of the present application, the step of calculating the maximum discharge power of the battery at the corresponding position according to the linear fitting relationship between the discharge current and the voltage difference includes:

Obtaining the second maximum voltage difference according to the above-mentioned fitted voltage difference-current curve and the above-mentioned third maximum discharge current;

Dividing the second maximum voltage difference by the third maximum discharge current to obtain the DC discharge resistance of the battery at the corresponding position;

Subtracting the product of the DC discharge resistance at the corresponding position and the third maximum discharge current from the open circuit voltage at the corresponding position to obtain the maximum supply voltage of the battery at the corresponding position; and

The third maximum discharge current at the corresponding position is multiplied by the above-mentioned maximum supply voltage to obtain the maximum discharge power at the corresponding position.

In the embodiment of the present application, the first maximum voltage difference ΔU _max is calculated according to the above formula (5). Then, the first maximum current corresponding to the first maximum voltage difference ΔU _max is determined according to the fitted voltage difference-current curve obtained when the discharge current and the voltage difference are linearly fitted or when the correlation coefficient of the linear fit is calculated before. I _max0 . Since the maximum discharge current allowed by the battery is not only limited by the cut-off voltage, but also limited by mechanical parts, the actual maximum discharge current I ^' _max allowed by the battery is determined according to the above formula (7), that is, the third maximum discharge current; I _max1 is the maximum discharge current limited by the cut-off voltage, that is, the second maximum discharge current. After determining the actual maximum discharge current _I'max allowed by the battery, according to the fitted voltage difference-current curve obtained when the discharge current and the voltage difference are linearly fitted or when the correlation coefficient of the linear fit is calculated before, determine The maximum voltage difference corresponding to I' _max is the second maximum voltage difference ΔU' _max . Next, calculate the DC discharge resistance DCR according to the above formula (9). Finally, the maximum discharge power P _max of the battery at the corresponding position is calculated according to the following formula (10):

P _max = (OCV-I′ _max *DCR)*I′ _max (10).

In some embodiments of the present application, when the operating conditions covered by the calculated maximum discharge power meet the preset data sufficiency conditions, the discharge current and voltage difference are completed according to the existing data in the data table of the discharge current and voltage difference The data table, and based on the data in the completed discharge current and voltage difference data table, complete the data table of the maximum discharge power of the battery in the above-mentioned specified health state interval according to the linear fitting relationship between the discharge current and voltage difference.

In some embodiments of the present application, the preset data sufficiency conditions include that the calculated working conditions covered by the maximum discharge power meet the following requirements:

When the working conditions covered by the calculated maximum discharge power do not meet the preset data sufficiency conditions, it is judged whether the capacity of the battery at this data point has decayed by a preset percentage relative to the rated capacity of the battery;

When the capacity of the battery at this data point has decayed by a preset percentage relative to the rated capacity of the battery, the maximum attenuation rate of the maximum discharge power calculated at the same temperature relative to the maximum discharge power in the data table of the previous maximum discharge power , to calculate the maximum discharge power of the missing state of charge to complement the maximum discharge power of different temperatures and states of charge.

In the implementation of this application, when the data is not enough, it is judged whether the capacity of the battery has decayed by the percentage of mandatory update, if the preset percentage has not decayed, then continue to supplement the data; if the preset percentage has decayed, then follow the maximum discharge Supplementary data for power decay laws. This implementation scheme ensures that the data conforms to the changing law and avoids jumping points in the data table.

In some embodiments of the present application, the data table of the maximum discharge power of the battery is updated at the same time as the data table of the DC discharge resistance of the battery is updated.

A fourth aspect of the present application provides a battery management system, wherein the battery management system is configured to determine the maximum discharge power of the battery, and the battery management system includes:

at least one processor; and

a memory connected to at least one of the processors;

Wherein the memory stores instructions, and when the instructions are executed by the at least one processor, the instructions cause the at least one processor to execute the method for determining the maximum discharge power of the battery described in the third aspect above.

Description of drawings

In order to illustrate the technical solution of the present application more clearly, the accompanying drawings that need to be used in the embodiments of the present application will be briefly introduced below. Obviously, the accompanying drawings described below are only some implementations of the present application. Ordinary technicians can also obtain other drawings based on the drawings without creative labor. In the attached picture:

FIG. 1 illustrates a flow chart of a method for determining the DC discharge resistance of a battery according to one embodiment of the present application;

Figure 2a illustrates a flow chart of a method of determining a data table of DC discharge resistance of a battery according to an embodiment of the present application;

Fig. 2b illustrates a flow chart of a method for updating a data table of discharge current and voltage difference according to the mutuality between data according to an embodiment of the present application;

Figure 2c illustrates a flow chart of a method for calculating the DC discharge resistance of a battery at a corresponding position according to a linear fitting relationship between the discharge current and the voltage difference according to an embodiment of the present application;

FIG. 3 illustrates a flowchart of a method for determining a maximum discharge power of a battery according to an embodiment of the present application;

Figure 4a illustrates a flow chart of a method of determining a data table of the maximum discharge power of a battery according to an embodiment of the present application;

Figure 4b illustrates a flow chart of a method for calculating the maximum discharge power of a battery at a corresponding position according to a linear fitting relationship between discharge current and voltage difference according to an embodiment of the present application; and

FIG. 5 is a schematic diagram of a battery management system according to an embodiment of the present application.

Detailed ways

Embodiments of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solution of the present application more clearly, and therefore are only examples, and should not be used to limit the protection scope of the present application.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the application; the terms used herein are only for the purpose of describing specific embodiments, and are not intended to be To limit this application; the terms "comprising" and "having" and any variations thereof in the specification and claims of this application and the description of the above drawings are intended to cover a non-exclusive inclusion.

In the description of the embodiments of the present application, the technical terms "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features , a specific order or a primary-secondary relationship.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The occurrences of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is understood explicitly and implicitly by those skilled in the art that the embodiments described herein can be combined with other embodiments.

In the description of the embodiments of the present application, the term "and/or" is only an association relationship describing associated objects, which means that there may be three relationships, such as A and/or B, which may mean: there is A, and there is A at the same time and B, there are three cases of B. In addition, the character "/" in this article generally indicates that the contextual objects are an "or" relationship. In the description of the embodiments of the present application, the term "plurality" refers to two or more (including two), unless otherwise clearly and specifically defined.

If steps are recited in order in the specification or claims, this does not necessarily mean that the embodiments or aspects are limited to the recited order. Rather, it is conceivable that the steps are also carried out in a different order or in parallel to each other, unless one step builds on another, which absolutely requires that the built-in steps be carried out subsequently (however this will become clear in individual cases) . Therefore, the stated order may be a preferred embodiment.

At present, batteries are not only used in energy storage power systems such as water power, fire power, wind power and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, as well as military equipment and aerospace. field. With the continuous expansion of battery application fields, its market demand is also constantly expanding.

The inventor found in practice that the conventional method of obtaining the maximum available power of the battery is to search the data table of the stored discharge power according to the SOC and the battery temperature to obtain the target output power, and then according to the voltage deviation between the minimum cell voltage and the cut-off voltage or A coefficient related to the state of health (SOH) to adjust the maximum available power. However, on the one hand, there may be jumps in the temperature or SOC dimension in the pre-stored discharge power data table, that is, a certain power value in the data table is too far from the power value of the front and rear temperatures or the front and rear SOC, which does not meet the power requirements. This is because the measured voltage data is not verified to be reasonable, and therefore the maximum available power obtained in this way is invalid. On the other hand, adjusting the maximum available power only with a single-point voltage or a coefficient related to SOH is only a rough estimate and cannot accurately reflect the state of performance parameters of the battery under the current SOH.

In order to accurately reflect the state of performance parameters of the battery under the current SOH, the inventor thought of regularly updating the data table of the discharge power so as to relatively accurately reflect the state of the performance parameters of the battery under the current SOH. In addition, in order to ensure the availability of the maximum available power obtained, the inventor thought of performing a series of screening and preprocessing on the obtained raw data before storing the obtained raw data in the data table, so that the data stored in the data table The data is reasonable and relatively reliable.

FIG. 1 illustrates a flowchart of a method 100 for determining a DC discharge resistance of a battery according to an embodiment of the present application. As shown in Figure 1, in step 102, the working condition data of the battery in the specified health state interval is obtained, the working condition data includes the temperature, state of charge, current, voltage and health state of the battery, and the above specified healthy state interval is The state of health interval corresponding to the latest state of health point specified for updating the data table of the DC discharge resistor that the battery has experienced. Then, at step 104, according to the working condition data in the specified health state interval, the data table of the DC discharge internal resistance of the battery in the above specified health state interval is determined. In step 106, the current temperature and current state of charge of the battery are obtained. In step 108, the DC discharge resistance of the battery is determined according to the data table of the DC discharge resistance within the specified health state interval, the current temperature and the current state of charge. In other words, look up the DC discharge resistor corresponding to the current temperature and state of charge in the DC discharge resistor's data sheet.

The method 100 for determining the DC discharge resistance of a battery shown in FIG. 1 continuously updates the data table of the DC discharge resistance during the entire life cycle of the battery, thereby ensuring the accuracy of the determined DC discharge resistance.

FIG. 2 a illustrates a flowchart of a method 200 a of determining a data table of a DC discharge resistance of a battery according to an embodiment of the present application. As shown in FIG. 2 a , in step 202 , from the working condition data within the specified health state interval, the data segments satisfying the preset working condition conditions are filtered out. In some embodiments of the present application, the preset operating conditions include a static period and a pulse period, the static period requires a current rate of less than or equal to 0.05C and a duration greater than or equal to 30 seconds, and the pulse period requires an average current The rate is greater than or equal to 0.2C, the state of charge is greater than or equal to 30%, and the duration is greater than or equal to 2 seconds. In a preferred embodiment of the present application, after judging that the working condition data satisfies the requirements of the static section, it is then judged whether the working condition data meets the requirements of the pulse section. In the embodiment of the present application, the preset working conditions ensure that the discharge current and the voltage difference are in a linear range, so that the DC discharge resistance calculated according to the linear fitting relationship between the discharge current and the voltage difference is relatively reliable. After filtering out the data segments satisfying the preset working conditions, it is judged whether the pulse segments in the data segments are quasi-constant current, step 204 .

If the pulse segment does not satisfy the quasi-constant current condition, convert the current in the pulse segment into an equivalent constant current, step 206 . In some embodiments of the present application, the quasi-constant current condition is that the current fluctuates no more than ±7%, preferably ±5%. Furthermore, in some embodiments of the present application, the equivalent constant current is calculated according to the above formulas (1) and (2). After the current is converted into an equivalent constant current, in step 208, it is judged whether the current of the data point in the above data segment is within a preset current range. If the pulse segment satisfies the quasi-constant current condition, it does not need to perform constant current conversion, and directly enters step 208 . In some embodiments of the present application, the preset current interval is between 0.05 times and 0.8 times of the maximum discharge current, and the above maximum discharge current is the temperature and charge corresponding to the working condition of the battery with rated capacity at the above data points The maximum current allowed for discharge in the state. In some embodiments of the present application, the preset current range includes three current ranges, the first current range of the three current ranges is between 0.05 and 0.2 times the maximum discharge current, and the third current range of the three current ranges is between 0.05 and 0.2 times the maximum discharge current. The second current range is between 0.2 and 0.4 times the maximum discharge current, and the third current range in the three current ranges is between 0.4 and 0.8 times the maximum discharge current. The above maximum discharge current is a battery with a rated capacity. The operating conditions of the above data points correspond to the temperature and the maximum current allowed for discharge in the state of charge. In the embodiment of the present application, as described before, it is necessary to judge whether the current of the data points in the data segment is within the preset current interval, and ensure that the data of the current and voltage difference are within the linear range to obtain higher usability The linear fitting curve of .

If the current of the data point is within the preset current interval, update the discharge current and The data table of the voltage difference, step 210; otherwise, return to step 202 to obtain the working condition data of the next data point.

After updating the data table of discharge current and voltage difference, in step 212, it is judged whether the data of the corresponding position in the data table of discharge current and voltage difference satisfies the preset sufficient condition, so as to determine whether the data of the corresponding position can be The discharge current and voltage difference were linearly fitted. In some embodiments of the present application, the preset sufficient conditions include: the current at the corresponding position in the two-dimensional data table of the discharge current and voltage difference is distributed in a plurality of preset current intervals; and the discharge current and voltage The square of the correlation coefficient R ² of the linear fitting of the current I and the voltage difference ΔU at the corresponding position in the difference two-dimensional data table is greater than or equal to 0.95. Through the preset sufficient conditions, it is ensured that the current and voltage difference data used to calculate the DC discharge resistance are grouped, linear fitting can be performed, and the error of the linear fitting is small enough.

When the preset sufficient condition is met, calculate the DC discharge resistance of the battery at the corresponding position according to the linear fitting relationship between the discharge current and the voltage difference, step 214; otherwise, return to step 202 to obtain the working condition data of the next data point. Next, in step 216, it is judged whether the working condition covered by the calculated DC discharge resistance satisfies the preset data adequacy condition, so as to judge whether the discharge can be reasonably completed according to the existing data in the data table of the discharge current and voltage difference. All data in the current and dropout voltage datasheet. In some embodiments of the present application, the preset data sufficiency conditions include that the calculated operating conditions covered by the DC discharge resistance meet the following requirements: the covered temperature includes at least three groups of temperatures between -20 and 25°C, and at least three groups Each set of temperatures is separated by greater than or equal to 10°C; the covered temperatures include at least two sets of temperatures between 25 and 55°C, each of the at least two sets of temperatures separated by greater than or equal to 10°C; and the covered charge The state between 30% and 100% includes at least two groups of states of charge, and the interval between each group of states of charge in the at least two groups of states of charge is greater than or equal to 20%. The preset data sufficiency condition ensures that the data stored in the discharge current and voltage difference data table is sufficient, so that all the data in the discharge current and voltage difference data table can be completed by linear interpolation and other methods.

If the preset data adequacy condition is satisfied, the data tables of discharge current and voltage difference are completed according to the existing data in the data table of discharge current and voltage difference, and the data of discharge current and voltage are completed based on the data in the completed data table The poor linear fitting relationship is used to complete the data table of the DC discharge resistor, step 218 . The data table of discharge current and voltage difference is completed by interpolation, which ensures that the data in the data table of discharge current and voltage difference conforms to the law of change and does not appear jumping points; correspondingly, the data table of the subsequently determined DC discharge resistance And the data sheet for the maximum discharge power does not appear to jump.

In some embodiments of the present application, firstly, linear fitting is performed on the discharge current and the voltage difference of the known temperature and state of charge, and the existing temperature and state of charge are complemented according to the fitted ΔU-I curve. The voltage difference between multiple preset current intervals. For example, Table 1 below illustrates a data table of discharge current and voltage difference for known temperatures and known states of charge. According to the known ΔU of 0.05*I _max , 0.25*I _max , and 0.45*I _max at 30% SOC and -20°C in Table 1, the ΔU-I curve at 30% SOC and -20°C is obtained, and according to the The curve obtains the ΔU under the missing current rate, and thus reciprocates to complete the ΔU of different discharge rates at each temperature.

Table 1

Then, according to the voltage difference of the known temperature, state of charge and current, a linear interpolation is performed on the state of charge between 30% and 100%, so as to complement the voltage difference between 30% and 100% of the state of charge. For example, Table 2 below illustrates a data table of discharge current and voltage difference for known temperatures. According to the known ΔU of different SOC at -20°C and 0.05*I _max discharge rate in Table 2, the linear curve of ΔU-SOC at -20°C and 0.05*I _max is obtained, and the -20 is interpolated according to the linear curve ℃ and 0.05*I _max , the ΔU under SOC is missing, and the ΔU under different SOC at each temperature and discharge rate is complemented in this way.

Table 2

Finally, according to the voltage difference of known temperature, state of charge and current, linear fitting is performed on lnΔU and 1/T, where the unit of T is Kelvin, and interpolation is completed according to the fitted lnΔU-1/T curve in Voltage difference between -25 to 25°C and between 25 to 55°C. For example, Table 3 below illustrates a data table of discharge current and voltage difference for known states of charge. According to the known ΔU of different temperatures at SOC1 and 0.05*I _max discharge rate in Table 3, the linear curve of lnΔU-1/T of SOC1 and 0.05*I _max is obtained. The unit of T in the linear curve is Kelvin, and according to The linear curve interpolates and complements the ΔU at the missing temperature when SOC1 is 0.05*I _max , so that the ΔU at different temperatures under each state of charge and discharge rate is reciprocated.

table 3

If the calculated operating conditions covered by the DC discharge resistance do not meet the preset data adequacy condition, then go to step 220 to determine whether the capacity decay of the battery has reached the preset percentage. If the capacity of the battery has not decayed by the preset percentage, return to step 202 to acquire the working condition data of the next data point. If the capacity of the battery has decayed by a preset percentage, update the DC discharge resistance DCR of the existing data point, and complete the data table of the DC discharge resistance according to the growth law of the DC discharge resistance DCR, step 222 . In some embodiments of the present application, whenever the capacity of the battery decays by 5%, that is, ΔSOH>5%, it means that the internal parameters of the battery have changed greatly, and a new discharge current based on temperature and state of charge needs to be stored. A 2D table of voltage differences and updated data sheets for DC discharge resistors. In other words, when the capacity of the battery is 95%, 90%, 85%, 80% or the like, the data table of the DC discharge resistor is updated compulsorily by completing the data table of the DC discharge resistor according to the growth law of DCR. In some embodiments of the present application, according to the maximum growth rate of the DC discharge resistance calculated at the same temperature relative to the DC discharge resistance in the previous data sheet, the DC discharge resistance of the missing state of charge is calculated to complement the DC discharge resistance data table.

Fig. 2b illustrates a flow chart of a method 200b for updating a data table of discharge current and voltage difference according to an embodiment of the present application according to the mutuality between the data. As shown in FIG. 2 b , in step 2102 , it is judged whether the data of the data point is different from the data of the corresponding position in the data table of the discharge current and the voltage difference. In some embodiments of the present application, the criterion for judging that the data of the data point and the data of the corresponding position have mutual dissimilarity is that the current of the data point fluctuates up and down in the temperature of the data point relative to the data table of the discharge current and the voltage difference1 The current fluctuates more than 5% within ℃ and within 2% of the state of charge fluctuation. It should be understood that the measured data cannot completely correspond to the SOC and temperature points of the table positions in the two-dimensional table, so it is necessary to judge which cell of the data table the measured data falls in according to the mutuality judgment standard. In some embodiments of the present application, if data is stored in the grid where the measurement data falls, it is considered to have no mutuality, and if there is no data stored in the grid where the measurement data falls, it is considered to have mutuality .

If the data of the data point and the data of the corresponding position do not have mutual dissimilarity, the voltage difference ΔU' of the voltage at the end of the rest period in the data segment minus the voltage of the data point and the voltage difference ΔU of the corresponding position are averaged to obtain Replace the voltage difference at the corresponding position, and take the average value of the equivalent constant current Ieq of the data point and the current I at the corresponding position to replace the current at the corresponding position, step 2104 . Then, enter step 2116, store the current I and the voltage difference ΔU in the above-mentioned two-dimensional table according to different temperatures and SOCs.

If the data of the data point is different from the data of the corresponding position, it is determined whether the data of the corresponding position has values in multiple preset current intervals, step 2106 .

If the data at the corresponding position has values in multiple preset current intervals, calculate the discharge of the data at the corresponding position before and after using the data of the data point to replace the data in the current interval where the data point in the corresponding position is located The square of the correlation coefficient R ² of the linear fitting of the current and the voltage difference, and retain the data with greater R ² , step 2108 . Then, enter step 2116, store the current I and the voltage difference ΔU in the above-mentioned two-dimensional table according to different temperatures and SOCs. By retaining data where the square of the correlation coefficient is larger, the error of the linear fit to the current and voltage difference is made smaller. In some embodiments of the present application, the square of the correlation coefficient can be calculated according to the above formula (3) and formula (4).

If the data at the corresponding position does not have a value in the preset multiple current intervals, it is determined whether the data at the corresponding position has a value in the current interval where the current of the data point is located, step 2110 .

If the data at the corresponding position has no value in the current interval where the current of the data point is located, then enter step 2116 to store the current I and the voltage difference ΔU. If the data at the corresponding position has a value in the current interval where the current of the data point is located, go to step 2112, and in step 2112, determine whether the data of the data point is credible. In some embodiments of the present application, the judging principle for the reliability of the data of the data point includes: when the current of the data point is greater than the current of the data at the corresponding position in the current interval where the current of the data point is located, the voltage difference of the data point is greater than the corresponding The voltage difference of the location data in the current interval where the current of the data point is located; and the resistance of the data point fluctuates no more than 20% relative to the resistance of the data of the corresponding position in the current interval of the current location of the data point, wherein the resistance of the data point It is equal to the voltage difference of the data point divided by the discharge current, and the resistance of the data at the corresponding position in the current interval of the current of the data point is equal to the voltage difference of the data at the corresponding position in the current interval of the current of the data point divided by the discharge current. In the embodiment of the present application, the judging principle of data credibility can ensure that the data conforms to the change rule, and avoid jumping points in the data table.

If the data of the data point is not credible, the data of the data point is not stored, and the process returns to step 202 to obtain the working condition data of the next data point. If the data of the data point is credible, then enter step 2114, when the current of the data point is in the first current interval I1, keep the smaller data between the current of the data point and the current of the corresponding position in the first current interval I1 ; When the current of the data point is in the second current interval I2 or the third current interval I3, the current of the reserved data point and the current of the corresponding position in the corresponding second current interval I2 or the third current interval I3 are larger data. The operation in step 2114 preserves the current closer to both ends, so that the current distribution is more uniform, so that a more usable linear fitting curve can be obtained. After step 2114, enter step 2116 to store the current I and the voltage difference ΔU.

In the embodiment of the present application, the data table of the discharge current and the voltage difference is updated according to the mutuality, and the distribution of the data stored in the data table of the discharge current and the voltage difference can be controlled, so that the linear approximation of the discharge current and the voltage difference The availability of the fitting curve is higher, and it is more reliable to calculate the DC discharge resistance based on the linear fitting relationship between the discharge current and the voltage difference.

Fig. 2c illustrates a flow chart of a method 200c for calculating the DC discharge resistance of a battery at a corresponding position according to a linear fitting relationship between discharge current and voltage difference according to an embodiment of the present application. As shown in Figure 2c, in step 2142, the discharge current and voltage difference at the corresponding position are linearly fitted to obtain the slope k and pitch b of the fitted voltage difference-current curve; in step 2144, according to the charge of the battery The electric state-open circuit voltage curve and the SOC of the corresponding position are used to obtain the open circuit voltage OCV of the corresponding position; in step 2146, the cut-off voltage U of the battery is _subtracted from the open circuit voltage OCV of the corresponding position to obtain the first Maximum voltage difference ΔU _max ; in step 2148, find the discharge current corresponding to the first maximum voltage difference ΔU _max in the fitted voltage difference-current curve, as the first maximum discharge current I _max0 ; then, in step 2150, select the first The minimum value of a maximum discharge current I _max0 and a second maximum discharge current I _max1 is used as the maximum discharge current I' _max actually allowed by the battery, wherein the second maximum discharge current I _max1 is the discharge current limited by the mechanical parts of the battery; Step 2152, according to the voltage difference corresponding to the actual maximum discharge current _I'max of the battery in the fitted voltage difference-current curve, as the second maximum voltage difference _ΔU'max ; finally, in step 2154, the second maximum voltage The difference ΔU′ _max is divided by the maximum discharge current I′ _max actually allowed by the battery to obtain the DC discharge resistance DCR of the battery at the corresponding position. In short, as mentioned above, the DC discharge resistance DCR at the corresponding position is calculated according to the above formulas (5)-(9).

FIG. 3 illustrates a flowchart of a method 300 for determining a maximum discharge power of a battery according to an embodiment of the present application. As shown in Figure 3, in step 302, the working condition data of the battery within the specified health state interval is obtained, the working condition data includes the temperature, state of charge, current, voltage and state of health of the battery, and the specified health state interval is The health state interval corresponding to the latest health state point of the data table designated for updating the maximum discharge power that the battery has experienced. In some embodiments of the present application, the latest state of health point that the battery has experienced and is designated for updating the data table of the DC discharge resistance is the latest state of health point that the battery has experienced and is designated for updating the data table of the maximum discharge power. Then, at step 304 , according to the operating condition data in the specified health state interval, a data table of the maximum discharge power of the battery in the specified health state interval is determined. In step 306, the current temperature and current state of charge of the battery are obtained. In step 308, the maximum discharge power of the battery is determined according to the data table of the maximum discharge power within the specified health state interval, the current temperature and the current state of charge. In other words, find the maximum discharge power corresponding to the current temperature and state of charge in the maximum discharge power data table.

The method 300 for determining the maximum discharge power of the battery shown in FIG. 3 continuously updates the data table of the maximum discharge power during the entire life cycle of the battery, thereby ensuring the accuracy of the determined maximum discharge power and maximizing the performance of the battery. , while improving driving safety and power.

FIG. 4 a illustrates a flowchart of a method 400 a of determining a data table of a DC discharge resistance of a battery according to one embodiment of the present application. The method illustrated in FIG. 4a is similar to the method illustrated in FIG. 2a, and the same parts will not be repeated here. In Figure 4a, in step 414, the maximum discharge power of the battery at the corresponding position is calculated according to the linear fitting relationship between the discharge current and the voltage difference; in step 416, whether the operating conditions covered by the calculated maximum discharge power meet the preset Data adequacy conditions and the health state of the data point complement the data table of the maximum discharge power of the battery within the specified health state interval. In some embodiments of the present application, the preset data sufficiency condition satisfied by the working condition covered by the calculated maximum discharge power is the same as the preset data sufficiency condition satisfied by the calculated working condition covered by the DC discharge resistance. In addition, in step 418, the data table of the discharge current and the voltage difference is completed according to the existing data in the data table of the discharge current and the voltage difference, and based on the data in the completed data table, a linear simulation of the discharge current and the voltage difference is performed. In step 422, the maximum discharge power P _max of the existing data point is updated, and the data table of the maximum discharge power is completed according to the decay law of the maximum discharge power P _max . In some embodiments of the present application, according to the maximum attenuation value of the maximum discharge power calculated at the same temperature relative to the maximum discharge power in the previous data table, the maximum discharge power of the missing state of charge is calculated to complement the maximum discharge power data table.

Fig. 4b illustrates a flowchart of a method 400b for calculating the maximum discharge power of a battery at a corresponding position according to a linear fitting relationship between discharge current and voltage difference according to an embodiment of the present application. The method 400b for calculating the maximum discharge power illustrated in FIG. 4b is similar to the method 300c for calculating the DC discharge resistance illustrated in FIG. 3c. The difference of method 400b is that after the DC discharge resistance is calculated in step 4154, in step 4156, the open circuit voltage OCV at the corresponding position is subtracted from the DC discharge resistance DCR at the corresponding position and the actual maximum discharge current I of the battery. ' _max to obtain the maximum power supply voltage U _S of the battery at the corresponding position, and multiply the maximum discharge current I' _max actually allowed by the battery at the corresponding position by the above maximum power supply voltage U _S to obtain the maximum discharge at the corresponding position Power P _max . In other words, as described above, the maximum discharge power P _max is calculated according to the above formula (10).

Based on the same inventive concept, please refer to FIG. 5 , an embodiment of the present application also provides a battery management system 500, including: at least one processor 501; and a memory 502 communicatively connected to the processor 501; wherein, the memory 502 stores There are instructions executable by the processor. When the instructions are executed by the processor 501, the instructions cause the processor 501 to execute the method for determining the DC discharge resistance of the battery and/or for determining the DC discharge resistance of the battery provided by the embodiments of the present application. method of maximum discharge power.

Wherein, the processor 501 and the memory 502 are electrically connected directly or indirectly to realize data transmission or interaction. For example, these components can be electrically connected through one or more communication buses or signal buses. The methods for correcting the state of charge of the battery each include at least one software function module that can be stored in the memory 502 in the form of software or firmware.

The processor 501 may be an integrated circuit chip with signal processing capability. The processor 501 can be a general-purpose processor, including a central processing unit (Central Processing Unit, CPU), a network processor (Network Processor, NP), etc.; it can also be a digital signal processor, an application-specific integrated circuit, an off-the-shelf programmable gate array or Other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can realize or execute the various methods, steps and logic block diagrams disclosed in the embodiments of the present application. A general-purpose processor may be a microprocessor, or the processor may be any conventional processor, or the like.

The memory 502 can store various software programs and modules, such as the program instructions/modules corresponding to the method for determining the DC discharge resistance of the battery and/or the method and device for determining the maximum discharge power of the battery provided in the embodiments of the present application . The processor 501 executes various functional applications and data processing by running software programs and modules stored in the memory 502 , that is, implements the methods in the embodiments of the present application.

Memory 502 can include but not limited to random access memory (Random Access Memory, RAM), read-only memory (Read Only Memory, ROM), programmable read-only memory (Programmable Read-Only Memory, PROM), erasable read-only memory Memory (Erasable Programmable Read-Only Memory, EPROM), Electric Erasable Programmable Read-Only Memory (EEPROM), etc.

The aforementioned embodiments and specific examples of the method for determining the DC discharge resistance of the battery and the method for determining the maximum discharge power of the battery are also applicable to the battery management system 500 shown in FIG. 5 . A detailed description of the method for the DC discharge resistance and the method for determining the maximum discharge power of the battery, those skilled in the art can clearly know the implementation method of the battery management system 500 in FIG. More details.

In addition, the present application also provides a device, which includes: a battery; and a battery management system as shown in FIG. 5 . Batteries can be used as a power source for a device or as an energy storage unit for a device. Devices can be, but not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, Electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. A device can choose a battery according to its usage needs.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for parts thereof without departing from the scope of the invention. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

A method for determining the DC discharge resistance of a battery, characterized in that the method comprises:

Obtaining the working condition data of the battery within a specified health state interval, the working condition data including the temperature, state of charge, current, voltage, and state of health of the battery, and the specified healthy state interval is the specified The health state interval corresponding to the latest health state point of the data table used to update the DC discharge resistor;

Determine the data table of the DC discharge resistance of the battery in the specified health state interval according to the working condition data of the battery in the specified health state interval;

obtaining the current temperature and current state of charge of the battery; and

The DC discharge resistance of the battery is determined according to the data table of the DC discharge resistance within the specified health state interval and the current temperature and the current state of charge.
The method according to claim 1, wherein the data table for determining the DC discharge resistance of the battery within the specified health state interval comprises:

Filtering out data segments that meet preset working condition conditions from the working condition data within the specified health state interval;

When the current of the data point in the data segment is within the preset current interval, according to the difference between the data of the data point and the data of the corresponding position of the data point in the discharge current and voltage difference data table Mutuality to update the data table for discharge current and voltage difference;

When the data at the corresponding position satisfies a preset sufficient condition, calculate the DC discharge resistance of the battery at the corresponding position according to the linear fitting relationship between the discharge current and the voltage difference; and

Completing the data table of the DC discharge resistance of the battery within the specified health state interval according to whether the calculated operating conditions covered by the DC discharge resistance meet the preset data adequacy condition and the health status of the data points.
The method according to claim 2, wherein determining the data table of the DC discharge resistance of the battery within the specified health state interval comprises the following steps:

When the current in the pulse segment of the data segment does not meet the quasi-constant current condition, the current in the pulse segment of the data segment is converted into an equivalent constant current.
The method according to claim 3, wherein the equivalent constant current is calculated according to the following formula:

Among them, I eq represents the equivalent constant current, w(t) represents the weight function, I(t) represents the discharge current at the sampling time point, t end represents the end time of the pulse segment, n is a positive integer and 2≤n ≤6.
The method according to any one of claims 2 to 4, wherein the preset current interval includes three current intervals, and the first current interval among the three current intervals is within 0.05 of the maximum discharge current. times to 0.2 times, the second current interval in the three current intervals is between 0.2 and 0.4 times the maximum discharge current, and the third current interval in the three current intervals is between the maximum Between 0.4 times and 0.8 times of the discharge current, the maximum discharge current is the maximum current allowed for discharge of the battery with rated capacity at the temperature and state of charge corresponding to the working condition of the data point.
The method according to any one of claims 2 to 5, wherein determining the data table of the DC discharge resistance of the battery within the specified health state interval comprises the following steps:

When the data of the data point and the data of the corresponding position do not have mutual dissimilarity:

Taking the average value of the voltage difference between the voltage at the end of the rest period in the data segment and the voltage of the data point and the voltage difference between the corresponding position and the data of the data point that has no mutual difference to replace the the voltage difference of the data having no mutuality between the corresponding position and the data of the data point; and

Taking the average value of the current of the data point and the current of the data having no dissimilarity between the corresponding position and the data of the data point to replace the current of the data having no dissimilarity between the corresponding position and the data of the data point .
The method according to any one of claims 2 to 6, wherein determining the data table of the DC discharge resistance of the battery within the specified health state interval comprises the following steps:

When the data of the data point is different from the data of the corresponding position, update the discharge current and voltage according to the relationship between the data of the data point and the data of the corresponding position in the preset current interval Bad data table, wherein the preset current range includes a plurality of current ranges.
The method according to claim 7, characterized in that, according to the relationship between the data of the data point and the data of the corresponding position within the preset current interval, the step of updating the data table of the discharge current and the voltage difference include:

When the data of the corresponding position is distributed in the plurality of current intervals, comparing the corresponding position before and after replacing the data of the current interval where the data point in the corresponding position is replaced by the data of the data point The square of the correlation coefficient of the data to the discharge current and voltage difference linear fitting;

When the square of the correlation coefficient using the data of the data point is larger, the data of the data point is stored in the data table of the discharge current and the voltage difference.
The method according to claim 7 or 8, characterized in that the data table of discharge current and voltage difference is updated according to the relationship between the data of the data point and the data of the corresponding position within the preset current interval The steps include:

When the data at the corresponding position is not distributed in the multiple current intervals, judging whether the data at the corresponding position has a value in the current interval where the current of the data point is located;

When the data at the corresponding position has no value in the current interval where the current of the data point is located, the data of the data point is stored in a data table of discharge current and voltage difference.
The method according to claim 9, characterized in that, according to the relationship between the data of the data point and the data of the corresponding position within the preset current interval, the step of updating the data table of the discharge current and the voltage difference include:

When the data at the corresponding position has a value in the current interval where the current of the data point is located, determine whether the data of the data point is credible; and

Where the data for said data point is credible:

When the current of the data point is in the current interval with the smallest current value among the plurality of current intervals, the current of the data point is compared with the current interval of the corresponding position in the current interval with the smallest current value among the plurality of current intervals The data of the smaller current value in the current is stored in the data table of discharge current and voltage difference;

When the current of the data point is not in the current interval with the smallest current value among the plurality of current intervals, comparing the current of the data point with the current of the corresponding position in the current interval where the current of the data point is located Data for large current values is stored in the discharge current and voltage difference data tables.
The method according to claim 9, wherein the preset current interval includes three current intervals, and the first current interval among the three current intervals is between 0.05 times and 0.2 times of the maximum discharge current The second current interval among the three current intervals is between 0.2 and 0.4 times the maximum discharge current, and the third current interval among the three current intervals is between 0.4 and 0.4 times the maximum discharge current. Between 0.8 times, the maximum discharge current is the maximum current allowed to discharge the battery with rated capacity at the temperature and state of charge corresponding to the working condition of the data point;

Where the data for said data point is credible:

When the current of the data point is in the first current interval, the data of the smaller current value of the current of the data point and the current of the corresponding position in the first current interval is stored in the discharge current and in the datasheet for the voltage difference;

When the current of the data point is in the second current interval or the third current interval, comparing the current of the data point with the current of the corresponding position in the current interval where the current of the data point is located Data for large current values is stored in the discharge current and voltage difference data tables.
The method according to claim 10 or 11, characterized in that the judging principles of the data credibility of the data points include:

When the current of the data point is greater than the current of the data at the corresponding position in the current interval where the current of the data point is located, the voltage difference of the data point is greater than the current of the data at the corresponding position at the data point the voltage difference in the current interval; and

The resistance of the data point fluctuates by no more than 20% in the resistance of the current interval where the current of the data point is located relative to the data at the corresponding position, wherein the resistance of the data point is equal to the voltage difference of the data point divided by The current, and the resistance of the data at the corresponding position in the current interval where the current of the data point is equal to the voltage difference of the data at the corresponding position in the current interval where the current of the data point is divided by the current.
The method according to any one of claims 2 to 12, wherein the voltage difference of the data point is equal to the voltage at the end of the rest period in the data segment minus the voltage of the data point; and

The current of the data point is the absolute value of the discharge current of the battery.
The method according to any one of claims 2 to 13, wherein the preset current range includes a plurality of current ranges, and the preset sufficient conditions include:

The data of the corresponding positions in the data table of the discharge current and the voltage difference are distributed in the plurality of current intervals; and

The square of the correlation coefficient of the linear fitting of the discharge current and the voltage difference at the corresponding position in the data table of the discharge current and the voltage difference is greater than or equal to 0.95.
The method according to any one of claims 2 to 14, wherein the step of calculating the DC discharge resistance of the battery at the corresponding position according to the linear fitting relationship between the discharge current and the voltage difference comprises:

performing linear fitting on the discharge current and the voltage difference at the corresponding position to obtain the slope and pitch of the fitted voltage difference-current curve;

Obtaining the open circuit voltage at the corresponding position according to the state of charge-open circuit voltage curve of the battery and the state of charge at the corresponding position;

Subtracting the cut-off voltage of the battery from the open circuit voltage at the corresponding position to obtain the first maximum voltage difference at the corresponding position;

Obtaining a first maximum discharge current according to the fitted voltage difference-current curve and the first maximum voltage difference;

Selecting the minimum value of the first maximum discharge current and the second maximum discharge current as the third maximum discharge current, wherein the second maximum discharge current is a discharge current limited by mechanical parts of the battery;

Obtaining a second maximum voltage difference according to the fitted voltage difference-current curve and the third maximum discharge current; and

Dividing the second maximum voltage difference by the third maximum discharge current to obtain the DC discharge resistance of the battery at the corresponding position.
The method according to any one of claims 2 to 15, characterized in that, when the calculated operating conditions covered by the DC discharge resistance meet the preset data adequacy condition, according to the discharge current and voltage difference in the data table Existing data complement the data table of discharge current and voltage difference, and based on the data in the data table of the completed discharge current and voltage difference, complete the battery in the said battery according to the linear fitting relationship between discharge current and voltage difference Data table for DC discharge resistors within specified health state intervals.
The method according to any one of claims 2 to 16, wherein the preset data sufficiency conditions include that the calculated operating conditions covered by the DC discharge resistance meet the following requirements:

The covered temperatures include at least three sets of temperatures between -20 and 25°C, each of the at least three sets of temperatures separated by greater than or equal to 10°C;

The covered temperatures include at least two sets of temperatures between 25 and 55°C, each of said at least two sets of temperatures separated by greater than or equal to 10°C; and

The covered states of charge between 30% and 100% include at least two groups of states of charge, and the interval between each group of states of charge in the at least two groups of states of charge is greater than or equal to 20%.
The method according to any one of claims 2 to 17, wherein the step of completing the data table of the discharge current and the voltage difference according to the existing data in the data table of the discharge current and the voltage difference comprises:

performing linear fitting on the current and voltage difference of the existing temperature and state of charge, and complementing the voltage difference in the preset current range of the existing temperature and state of charge according to the fitted ΔU-I curve;

performing linear interpolation for the voltage difference between 30% and 100% of the state of charge to complement the voltage difference between 30% and 100% of the state of charge based on the voltage difference of the known temperature, state of charge and current; and

According to the voltage difference of known temperature, state of charge and current, perform linear fitting on lnΔU and 1/T, where the unit of T is Kelvin, and interpolate according to the fitted lnΔU-1/T curve at -25 to 25°C and the voltage difference between 25 to 55°C.
The method according to any one of claims 2 to 18, wherein determining the data table of the DC discharge resistance of the battery within the specified health state interval comprises the following steps:

When the calculated operating conditions covered by the DC discharge resistance do not meet the preset data adequacy condition, judging whether the capacity of the battery at the data point has decayed by a preset percentage relative to the rated capacity of the battery;

When the capacity of the battery at the data point has decayed by a preset percentage relative to the rated capacity of the battery, the DC discharge resistance calculated at the same temperature relative to the specified health state interval in the previous health state interval The maximum growth rate of the DC discharge resistance in the data table of the DC discharge resistance, calculate the DC discharge resistance of the missing state of charge, to complement the DC discharge resistance of different temperatures and states of charge.
A battery management system, characterized in that the battery management system is configured to determine the DC discharge resistance of the battery, and the battery management system includes:

at least one processor; and

a memory connected to the at least one processor;

Wherein the memory stores instructions which, when executed by the at least one processor, cause the at least one processor to perform the method for determining a battery according to any one of claims 1 to 19 DC discharge resistor method.
A method for determining the maximum discharge power of a battery, characterized in that the method comprises:

Obtaining the working condition data of the battery within a specified health state interval, the working condition data including the temperature, state of charge, current, voltage, and state of health of the battery, and the specified healthy state interval is the specified The health state interval corresponding to the latest health state point of the data table used to update the maximum discharge power;

determining the data table of the maximum discharge power of the battery in the specified health state interval according to the working condition data of the battery in the specified health state interval;

obtaining the current temperature and current state of charge of the battery; and

The maximum discharge power of the battery is determined according to the data table of the maximum discharge power within the specified health state interval, the current temperature and the current state of charge.
The method according to claim 21, wherein the data table for determining the maximum discharge power of the battery within the specified health state interval comprises:

Filtering out data segments that meet preset working condition conditions from the working condition data within the specified health state interval;

When the current of the data point in the data segment is within the preset current interval, according to the difference between the data of the data point and the data of the corresponding position of the data point in the discharge current and voltage difference data table Mutuality to update the data table for discharge current and voltage difference;

When the data at the corresponding position satisfies a preset sufficient condition, calculate the maximum discharge power of the battery at the corresponding position according to the linear fitting relationship between the discharge current and the voltage difference; and

According to whether the working condition covered by the calculated maximum discharge power satisfies the preset data adequacy condition and the health state of the data points, the data table of the maximum discharge power of the battery in the specified health state interval is completed.
The method according to claim 22, wherein determining the data table of the maximum discharge power of the battery within the specified health state interval comprises the following steps:

When the current in the pulse segment of the data segment does not meet the quasi-constant current condition, the current in the pulse segment of the data segment is converted into an equivalent constant current.
The method according to claim 23, wherein the equivalent constant current is calculated according to the following formula:

Among them, I eq represents the equivalent constant current, w(t) represents the weight function, I(t) represents the discharge current at the sampling time point, t end represents the end time of the pulse segment, n is a positive integer and 2≤n ≤6.
The method according to any one of claims 22 to 24, wherein the preset current interval includes three current intervals, and the first current interval among the three current intervals is within 0.05 of the maximum discharge current. times to 0.2 times, the second current interval in the three current intervals is between 0.2 and 0.4 times the maximum discharge current, and the third current interval in the three current intervals is between the maximum Between 0.4 times and 0.8 times of the discharge current, the maximum discharge current is the maximum current allowed for discharge of the battery with rated capacity at the temperature and state of charge corresponding to the working condition of the data point.
The method according to any one of claims 22 to 25, wherein determining the data table of the maximum discharge power of the battery within the specified health state interval comprises the following steps:

When the data of the data point and the data of the corresponding position do not have mutual dissimilarity:

Taking the average value of the voltage difference between the voltage at the end of the rest period in the data segment and the voltage of the data point and the voltage difference between the corresponding position and the data of the data point that has no mutual difference to replace the the voltage difference of the data having no mutuality between the corresponding position and the data of the data point; and

Taking the average value of the current of the data point and the current of the data having no dissimilarity between the corresponding position and the data of the data point to replace the current of the data having no dissimilarity between the corresponding position and the data of the data point .
The method according to any one of claims 22 to 26, wherein determining the data table of the maximum discharge power of the battery within the specified health state interval comprises the following steps:

When the data of the data point is different from the data of the corresponding position, update the discharge current and voltage according to the relationship between the data of the data point and the data of the corresponding position in the preset current interval Bad data table, wherein the preset current range includes a plurality of current ranges.
The method according to claim 27, characterized in that, according to the relationship between the data of the data point and the data of the corresponding position within the preset current interval, the step of updating the data table of the discharge current and the voltage difference include:

When the data of the corresponding position is distributed in the plurality of current intervals, comparing the corresponding position before and after replacing the data of the current interval where the data point in the corresponding position is replaced by the data of the data point The square of the correlation coefficient of the data to the discharge current and voltage difference linear fitting;

When the square of the correlation coefficient using the data of the data point is larger, the data of the data point is stored in the data table of the discharge current and the voltage difference.
The method according to claim 27 or 28, characterized in that the data table of discharge current and voltage difference is updated according to the relationship between the data of the data point and the data of the corresponding position within the preset current interval The steps include:

When the data at the corresponding position is not distributed in the multiple current intervals, judging whether the data at the corresponding position has a value in the current interval where the current of the data point is located;

When the data at the corresponding position has no value in the current interval where the current of the data point is located, the data of the data point is stored in a data table of discharge current and voltage difference.
The method according to claim 29, characterized in that, according to the relationship between the data of the data point and the data of the corresponding position within the preset current interval, the step of updating the data table of the discharge current and the voltage difference include:

When the data at the corresponding position has a value in the current interval where the current of the data point is located, determine whether the data of the data point is credible; and

Where the data for said data point is credible:

When the current of the data point is in the current interval with the smallest current value among the plurality of current intervals, the current of the data point is compared with the current interval of the corresponding position in the current interval with the smallest current value among the plurality of current intervals The data of the smaller current value in the current is stored in the data table of discharge current and voltage difference;

When the current of the data point is not in the current interval with the smallest current value among the plurality of current intervals, comparing the current of the data point with the current of the corresponding position in the current interval where the current of the data point is located Data for large current values is stored in the discharge current and voltage difference data tables.
The method according to claim 29, wherein the preset current interval includes three current intervals, and the first current interval among the three current intervals is between 0.05 times and 0.2 times of the maximum discharge current The second current interval among the three current intervals is between 0.2 and 0.4 times the maximum discharge current, and the third current interval among the three current intervals is between 0.4 and 0.4 times the maximum discharge current. Between 0.8 times, the maximum discharge current is the maximum current allowed to discharge the battery with rated capacity at the temperature and state of charge corresponding to the working condition of the data point;

Where the data for said data point is credible:

When the current of the data point is in the first current interval, the data of the smaller current value of the current of the data point and the current of the corresponding position in the first current interval is stored in the discharge current and in the datasheet for the voltage difference;

When the current of the data point is in the second current interval or the third current interval, comparing the current of the data point with the current of the corresponding position in the current interval where the current of the data point is located Data for large current values is stored in the discharge current and voltage difference data tables.
The method according to claim 30 or 31, characterized in that, the judging principles for the credible data of the data points include:

When the current of the data point is greater than the current of the data at the corresponding position in the current interval where the current of the data point is located, the voltage difference of the data point is greater than the current of the data at the corresponding position at the data point the voltage difference in the current interval; and

The resistance of the data point fluctuates by no more than 20% in the resistance of the current interval where the current of the data point is located relative to the data at the corresponding position, wherein the resistance of the data point is equal to the voltage difference of the data point divided by The current, and the resistance of the data at the corresponding position in the current interval where the current of the data point is equal to the voltage difference of the data at the corresponding position in the current interval where the current of the data point is divided by the current.
The method according to any one of claims 22 to 32, wherein the voltage difference of the data point is equal to the voltage at the end of the rest period in the data segment minus the voltage of the data point; and

The current of the data point is the absolute value of the discharge current of the battery.
The method according to any one of claims 22 to 33, wherein the preset current range includes a plurality of current ranges, and the preset sufficient conditions include:

The data of the corresponding positions in the data table of the discharge current and the voltage difference are distributed in the plurality of current intervals; and

The square of the correlation coefficient of the linear fitting of the discharge current and the voltage difference at the corresponding position in the data table of the discharge current and the voltage difference is greater than or equal to 0.95.
The method according to any one of claims 22 to 34, wherein the step of calculating the maximum discharge power of the battery at the corresponding position according to the linear fitting relationship between the discharge current and the voltage difference comprises:

performing linear fitting on the discharge current and the voltage difference at the corresponding position to obtain the slope and pitch of the fitted voltage difference-current curve;

Obtaining the open circuit voltage at the corresponding position according to the state of charge-open circuit voltage curve of the battery and the state of charge at the corresponding position;

Subtracting the cut-off voltage of the battery from the open circuit voltage at the corresponding position to obtain the first maximum voltage difference at the corresponding position;

Obtaining a first maximum discharge current according to the fitted voltage difference-current curve and the first maximum voltage difference;

Selecting the minimum value of the first maximum discharge current and the second maximum discharge current as the third maximum discharge current, wherein the second maximum discharge current is a discharge current limited by mechanical parts of the battery;

Obtaining a second maximum voltage difference according to the fitted voltage difference-current curve and the third maximum discharge current;

dividing the second maximum voltage difference by the third maximum discharge current to obtain the DC discharge resistance of the battery at the corresponding position;

subtracting the product of the DC discharge resistance at the corresponding position and the third maximum discharge current from the open circuit voltage at the corresponding position to obtain the maximum supply voltage of the battery at the corresponding position; and

and multiplying the third maximum discharge current at the corresponding position by the maximum supply voltage to obtain the maximum discharge power at the corresponding position.
The method according to any one of claims 22 to 35, characterized in that, when the operating conditions covered by the calculated maximum discharge power meet the preset data adequacy condition, according to the discharge current and voltage difference in the data table Existing data complement the data table of discharge current and voltage difference, and based on the data in the data table of the completed discharge current and voltage difference, complete the battery in the said battery according to the linear fitting relationship between discharge current and voltage difference A data table specifying the maximum discharge power within a state of health interval.
The method according to any one of claims 22 to 36, wherein the preset data adequacy condition includes that the calculated operating conditions covered by the maximum discharge power meet the following requirements:

The covered temperatures include at least three sets of temperatures between -20 and 25°C, each of the at least three sets of temperatures separated by greater than or equal to 10°C;

The covered temperatures include at least two sets of temperatures between 25 and 55°C, each of said at least two sets of temperatures separated by greater than or equal to 10°C; and

The covered states of charge between 30% and 100% include at least two groups of states of charge, and the interval between each group of states of charge in the at least two groups of states of charge is greater than or equal to 20%.
The method according to any one of claims 22 to 37, wherein the step of completing the data table of the discharge current and the voltage difference according to the existing data in the data table of the discharge current and the voltage difference comprises:

performing linear fitting on the current and voltage difference of the existing temperature and state of charge, and complementing the voltage difference in the preset current range of the existing temperature and state of charge according to the fitted ΔU-I curve;

performing linear interpolation for the voltage difference between 30% and 100% of the state of charge to complement the voltage difference between 30% and 100% of the state of charge based on the voltage difference of the known temperature, state of charge and current; and

According to the voltage difference of known temperature, state of charge and current, perform linear fitting on lnΔU and 1/T, where the unit of T is Kelvin, and interpolate according to the fitted lnΔU-1/T curve at -25 to 25°C and the voltage difference between 25 to 55°C.
The method according to any one of claims 22 to 38, wherein determining the data table of the maximum discharge power of the battery within the specified health state interval comprises the following steps:

When the working condition covered by the calculated maximum discharge power does not meet the preset data adequacy condition, it is judged whether the capacity of the battery at the data point has decayed by a preset percentage relative to the rated capacity of the battery;

When the capacity of the battery at the data point has attenuated by a preset percentage relative to the rated capacity of the battery, according to the maximum discharge power calculated at the same temperature relative to the maximum discharge power in the previous maximum discharge data table The maximum decay rate of power, calculate the maximum discharge power of the missing state of charge, to complement the maximum discharge power of different temperatures and states of charge.
A battery management system, characterized in that the battery management system is configured to determine the maximum discharge power of the battery, and the battery management system includes:

at least one processor; and

a memory connected to the at least one processor;

Wherein the memory stores instructions which, when executed by the at least one processor, cause the at least one processor to perform the method for determining a battery according to any one of claims 21 to 39 The method of maximum discharge power.