CN116930794A - Battery capacity updating method and device, electronic equipment and storage medium - Google Patents
Battery capacity updating method and device, electronic equipment and storage medium Download PDFInfo
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/385—Arrangements for measuring battery or accumulator variables
- G01R31/387—Determining ampere-hour charge capacity or SoC
- G01R31/388—Determining ampere-hour charge capacity or SoC involving voltage measurements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/08—Measuring resistance by measuring both voltage and current
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/3644—Constructional arrangements
- G01R31/3648—Constructional arrangements comprising digital calculation means, e.g. for performing an algorithm
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/374—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC] with means for correcting the measurement for temperature or ageing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/389—Measuring internal impedance, internal conductance or related variables
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Abstract
The invention discloses a battery capacity updating method, a device, electronic equipment and a storage medium, wherein the method comprises the following steps: when the battery is determined to meet the preset charging condition, charging the battery and acquiring charging data, and calculating the current impedance value of the battery according to the charging data; obtaining a reference impedance value of the battery at a reference temperature according to the current impedance value and a pre-generated impedance relational expression; and updating the compensation impedance value of the battery in the current state according to the reference impedance value, and updating the battery capacity of the battery according to the compensation impedance value. The technical scheme provided by the invention can solve the technical problem that the battery capacity precision is reduced due to the change of impedance after aging in the prior art.
Description
Technical Field
The present invention relates to the field of battery technologies, and in particular, to a method and apparatus for updating battery capacity, an electronic device, and a storage medium.
Background
With the demands of clean energy in the market and the demands of application markets, lithium batteries are increasingly widely used in daily life. The battery can output stable current, continuously provides energy for electronic products, and has very wide application. In order to realize detection of the electric quantity of the battery cell, in many application scenarios, a voltage test method is generally adopted to estimate the battery cell capacity of the lithium ion battery cell.
In battery management, an electricity meter is responsible for estimating battery capacity. Its basic functions are to monitor voltage, charge-discharge current and battery temperature, and to estimate the state of charge (SOC) of the battery and the Full Charge Capacity (FCC) of the battery. In fuel gauge chips with the CEDV algorithm, data at a cell capacity of 7% is typically of interest, i.e. the voltage value at which the cell discharge approaches the critical point.
In the use process of the battery, the aging phenomenon of the battery can occur along with the continuous charge and discharge of the battery. The existing CEDV technology has insufficient accuracy in calculating FCC. The capacity precision of the CEDV algorithm is reduced by 6-8% after the battery is used for 1 year, so that the algorithm precision difference can lead to the reduction of the battery service time by 6-8%, the user experience is poor, and the longer the battery service time is, the larger the influence is. The prior art relies on a fixed impedance value to estimate the full charge capacity (Full charge capacity, FCC) of the battery, but in practice, the impedance value of the battery is not fixed due to long-term storage and aging of the battery, and gradually changes with the use of the battery, and if the FCC is estimated only by means of the fixed impedance value, calculation errors occur, resulting in lower accuracy of the calculated FCC.
Disclosure of Invention
The invention provides a battery capacity updating method, a battery capacity updating device, electronic equipment and a storage medium, and aims to effectively solve the technical problem that in the prior art, as a battery ages, the accuracy of the battery capacity is reduced due to impedance change.
According to an aspect of the present invention, there is provided a battery capacity updating method including:
when the battery is determined to meet the preset charging condition, charging the battery and acquiring charging data, and calculating the current impedance value of the battery according to the charging data;
obtaining a reference impedance value of the battery at a reference temperature according to the current impedance value and a pre-generated impedance relational expression;
and updating the compensation impedance value of the battery in the current state according to the reference impedance value, and updating the battery capacity of the battery according to the compensation impedance value.
Further, determining that the battery meets the preset charging condition includes:
acquiring the charging current multiplying power, the charging temperature and the current voltage value of the battery;
determining that the charging current multiplying power is in a preset multiplying power interval, determining that the charging temperature is in a preset temperature interval, and determining that the current voltage value is a preset first voltage.
Further, the charging the battery and acquiring charging data includes:
when the current voltage value of the battery is the first voltage, changing the charging current from the first charging current to the second charging current, and after the charging time reaches the preset time, changing the charging current from the second charging current to the first charging current, and determining the current voltage value of the battery to be the second voltage.
Further, the calculating the current impedance value of the battery according to the charging data includes:
calculating a voltage difference between the first voltage and the second voltage, and calculating a current difference between the first charging current and the second charging current;
and calculating the ratio between the voltage difference and the current difference, and determining the ratio as the current impedance value.
Further, the impedance relation is generated by:
when the battery meets the charging condition, charging the test battery at a plurality of test temperatures, and obtaining charging test data, wherein the charging test data comprises a first test voltage and a corresponding first test charging current, and a second test voltage and a corresponding second test charging current;
calculating a plurality of battery impedance values of the test battery according to the first test voltage, the first test charging current, the second test voltage and the second test charging current corresponding to a plurality of test temperatures;
the impedance relationship is derived based on a plurality of battery impedance values and their corresponding test temperatures.
Further, the updating the compensation impedance value of the battery in the current state according to the reference impedance value includes:
acquiring an initial impedance value of the battery at the reference temperature when the battery is not in use;
calculating a charging impedance change rate according to the reference impedance value and the initial impedance value;
the compensation impedance value is calculated based on the reference impedance value and the charging impedance change rate.
Further, the calculating the charging impedance change rate from the reference impedance value and the initial impedance value includes:
calculating the charging impedance change rate according to the following formula:
D R ＝(R2-R1)/R1，
wherein D is R And R1 represents the initial impedance value, and R2 represents the reference impedance value.
Further, the calculating the compensation impedance value based on the reference impedance value, the charging impedance change rate includes:
calculating the compensation impedance value according to the following formula:
R0＝R1*(1+n*D R )，
wherein R0 represents the compensation impedance value, R1 represents the reference impedance value, D R And n represents a conversion coefficient of the charging impedance change rate and the discharging impedance change rate.
According to another aspect of the present invention, there is also provided a battery capacity updating apparatus including:
the first calculation module is used for charging the battery and acquiring charging data when the battery is determined to meet preset charging conditions, and calculating the current impedance value of the battery according to the charging data;
the second calculation module is used for obtaining a reference impedance value of the battery at a reference temperature according to the current impedance value and a pre-generated impedance relational expression;
and the battery capacity updating module is used for updating the compensation impedance value of the battery in the current state according to the reference impedance value and updating the battery capacity of the battery according to the compensation impedance value.
According to another aspect of the present invention, there is also provided an electronic apparatus including:
the device comprises a controller, a communication interface, a memory and a communication bus, wherein the controller, the communication interface and the memory are communicated with each other through the communication bus;
a memory for storing a computer program;
and the controller is used for executing the program stored in the memory so as to realize any one of the battery capacity updating methods.
According to another aspect of the present invention, there is also provided a storage medium having stored therein a plurality of instructions adapted to be loaded by a processor to perform any of the battery capacity updating methods as described above.
Through one or more of the above embodiments of the present invention, at least the following technical effects can be achieved:
in the technical scheme disclosed by the invention, a plurality of conditions are preset in advance, when the current state of the battery meets the charging conditions, the current impedance value of the battery is calculated according to the obtained charging data, so that a reference impedance value at a preset temperature is obtained, and then the compensation impedance value for calculating the battery capacity is updated according to the reference impedance value, so that the accurate battery capacity is calculated. According to the scheme, an additional circuit is not needed, corresponding parameters can be optimized through a single aging cycle test, the actual impedance value of the battery is calculated, and the operation is easy. The calculated accurate supplementary impedance value is used for replacing the fixed impedance value, so that the FCC is calculated, the problem that the FCC precision is insufficient after the battery is stored and aged for a long time is solved, and the accurate update of the FCC is realized.
Drawings
The technical solution and other advantageous effects of the present invention will be made apparent by the following detailed description of the specific embodiments of the present invention with reference to the accompanying drawings.
Fig. 1 is a flowchart of steps of a battery capacity updating method according to an embodiment of the present invention;
FIG. 2 is a graph of an impedance relationship provided by an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a battery capacity updating device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
In the description of the present invention, it should be noted that, unless explicitly specified and defined otherwise, the term "and/or" herein is merely an association relationship describing associated objects, and means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist together, and B exists alone. The character "/" herein generally indicates that the associated object is an "or" relationship unless otherwise specified.
Fig. 1 is a flowchart illustrating steps of a battery capacity updating method according to an embodiment of the present invention, where according to an aspect of the present invention, a battery capacity updating method is provided, and the method includes:
step 101: when the battery is determined to meet the preset charging condition, charging the battery and acquiring charging data, and calculating the current impedance value of the battery according to the charging data;
step 102: obtaining a reference impedance value of the battery at a reference temperature according to the current impedance value and a pre-generated impedance relational expression;
step 103: and updating the compensation impedance value of the battery in the current state according to the reference impedance value, and updating the battery capacity of the battery according to the compensation impedance value.
Illustratively, batteries used by electronic devices typically have an electricity meter chip with a CEDV algorithm therein, and during battery use, battery capacity (FCC) may be assessed based on the CEDV algorithm.
The CEDV (Compensated End of Discharge Voltage) algorithm is a coulomb integration-based coulometric algorithm that evaluates battery capacity from data obtained by charging and discharging the battery. When using the CEDV algorithm, during the discharging process of the battery, the 3 dynamic voltage points of EDV2, EDV1 and EDV0 are usually required to be paid attention to, which correspond to the dynamic voltages when the capacities of the battery cells are 7%, 3% and 0%, respectively.
Wherein the dynamic voltage point EDV2 at a cell capacity of 7% affects the accuracy of the estimated FCC. Specifically, in evaluating FCC, the battery is charged, and the battery is left to stand when the battery charge increases from 0 to 7% charge, resulting in a standing voltage V. Then, the full-charged battery is discharged, the dynamic voltage EDV2 when the battery is discharged to 7% from 100% of electric quantity is calculated, and the discharge current I and the battery impedance value R need to be obtained when the EDV2 is calculated, and EDV2=V-I. In the prior art, after the battery ages, the battery impedance value and the actual impedance value do not match, so that the calculated EDV2 has errors. In practice, the battery impedance value after aging increases, so the true EDV2 value should be smaller.
When calculating FCC, it is necessary to obtain the discharge current and the required discharge time t when the battery is charged from full to 7%, fcc=i×t/93%.
In the calculation formula of the FCC, the EDV2 value is inaccurate, so the calculated charging time is smaller than that of the actual charging time, and the FCC value is error.
Therefore, it is critical to determine the impedance value of the current battery. After the impedance value is clear, accurate dynamic voltage can be obtained, and then accurate discharge time is obtained, and finally accurate FCC is obtained.
When the discharging temperature or the impedance value of the battery is different, the voltage corresponding to the EDV2 point can be changed, when the FCC precision is updated by using the CEDV algorithm, the accurate compensation impedance value of the battery at the reference temperature of 25 ℃ is calculated, when the basic impedance value is clear, the impedance value of the battery during discharging is determined, then the battery automatically calculates the dynamic voltage EDV2, and further, the accurate FCC precision is calculated, and the FCC updating precision can be improved.
In this embodiment, the present impedance value, the reference impedance value, the initial impedance value, and the compensation impedance value of the battery are respectively referred to as a plurality of impedance values. In the using process of the battery, the discharging impedance can not be tested, and only the charging impedance can be tested, so that the discharging impedance needs to be calculated according to the charging impedance, wherein the current impedance value, the reference impedance value and the initial impedance value are all charging impedance, and the compensating impedance value is discharging impedance.
The current impedance value is the actual impedance value of the battery at the current temperature during use or during testing. For example, when the charge temperature or test temperature of the battery is 10 ℃, 30 ℃, 40 ℃, then the current impedance value is the true impedance value of the battery at 10 ℃, 30 ℃ or 40 ℃.
The reference impedance value is an impedance value of the used battery at a predetermined reference temperature, for example, assuming that the predetermined reference temperature is 25 ℃, the reference impedance value is an impedance value of the used battery at 25 ℃.
The initial impedance value is the impedance value of the battery at the contracted reference temperature before the battery is not used, for example, assuming the contracted reference temperature is 25 ℃, the initial impedance value is the impedance value of the new battery at 25 ℃ before the battery is used.
The compensation impedance value is an impedance value when the current electric quantity of the battery is 7% in the discharging process, wherein the compensation impedance value is an impedance value measured by the battery at a reference temperature, and in practical application, the reference temperature can be determined to be 25 ℃. After calculating the compensation impedance value, the battery electricity meter can automatically calculate the dynamic voltage and the discharging time according to the compensation impedance value, and calculate the Full Charge Capacity (FCC) of the battery.
The above steps 101 to 103 are specifically described below.
In step 101, when it is determined that the battery meets a preset charging condition, charging the battery and acquiring charging data, and calculating a current impedance value of the battery according to the charging data.
When the charging current multiplying power, the charging temperature and the current voltage value of the battery meet preset conditions, the battery is subjected to pulse charging, charging data such as current and voltage related to the battery are obtained, and the current impedance value of the battery is calculated according to the charging data.
Wherein, the charge current multiplying power, the charge temperature and the current voltage value of the battery need to meet the conditions. For example, the charging current multiplying power is between 0.5C and 1C, the charging temperature of the battery is between 15 ℃ and 45 ℃, and when both conditions are satisfied, the resistance value of the battery is also evaluated when the current voltage value of the battery is a preset first voltage, for example, the first voltage is 4150 mV.
In step 102, a reference impedance value of the battery at a reference temperature is obtained according to the current impedance value and a pre-generated impedance relation.
Illustratively, when the cell temperature of the battery changes, the impedance value of the battery changes with the temperature change. The method comprises the steps of storing a pre-generated impedance relation in an electricity meter chip of a battery, specifically, testing the battery before leaving the factory, changing the temperature value of the battery, calculating the impedance values of the battery at different temperatures through charging data, and fitting a change curve according to a plurality of groups of impedance values and temperature values to obtain the relation between the temperature and the impedance of the battery.
After the battery is aged continuously, the current impedance value of the battery changes, but the change trend between the temperature and the impedance does not change, and the characteristic is utilized to obtain the current reference impedance value of the battery at the preset reference temperature.
In step 103, the compensation impedance value of the battery under the preset electric quantity is updated according to the current impedance value.
Illustratively, when a battery ages, the current impedance value of the aged battery changes compared to a new battery, and correspondingly, the compensating impedance value of the CEDV algorithm under the preset electric quantity also changes, and if the compensating impedance value is not adjusted, the complete charge capacity (FCC) estimated by the CEDV algorithm has errors.
In fuel gauge chips with the CEDV algorithm, a voltage value at 7% of the cell capacity is typically of interest, i.e. the preset charge is 7% of the battery capacity. According to the scheme, the compensation impedance value of the battery under the preset electric quantity is updated according to the reference impedance value, so that the value of the Full Charge Capacity (FCC) can be accurately updated, and the problem of insufficient FCC precision after long-term storage and aging of the battery is solved.
Further, determining that the battery meets the preset charging condition includes:
acquiring the charging current multiplying power, the charging temperature and the current voltage value of the battery;
determining that the charging current multiplying power is in a preset multiplying power interval, determining that the charging temperature is in a preset temperature interval, and determining that the current voltage value is a preset first voltage.
Illustratively, the evaluation of the impedance value is started when the state at the time of charging the battery satisfies a preset condition, specifically, the charging current magnification, the charging temperature, and the present voltage value of the battery are required to satisfy the condition. For example, the charging current multiplying power is between 0.5C and 1C, the charging temperature of the battery is between 15 ℃ and 45 ℃, and when the two conditions are met, the current voltage value of the battery is required to be a preset first voltage, for example, the first voltage is 4150mV, and the impedance value of the battery is evaluated by using a pulse charging method.
The charging current multiplying power is a measure of the charging speed, and refers to the current value required by the battery when the battery is charged to the rated capacity at a specified time. Is numerically equal to a multiple of the battery rated capacity, i.e. "charging current/battery rated capacity=charging rate"; the charging temperature is the current temperature of the battery core of the battery; the current voltage value is a real-time voltage value of the battery monitored by the battery electricity meter during charging.
Further, the charging the battery and acquiring charging data includes:
when the current voltage value of the battery is the first voltage, changing the charging current from the first charging current to the second charging current, and after the charging time reaches the preset time, changing the charging current from the second charging current to the first charging current, and determining the current voltage value of the battery to be the second voltage.
In an exemplary embodiment, when the temperature value and the charging rate of the battery meet preset conditions, the cell voltage of the battery is monitored by an electricity meter built in the battery, and pulse charging is performed when the cell voltage reaches a preset first voltage. For example, before pulse charging, the battery is charged with a current of 2000mA, the charge amount in the battery cell is gradually increased, and accordingly, the battery cell voltage is also gradually increased, 4150mV is set as the trigger voltage in advance, when the battery cell voltage is detected to be 4150mV, the pulse charging is performed on the battery, for example, the charging current is changed from 2000mA to 100mA, after the charging lasts for 5 seconds, the current is restored to 2000mA, the charging is continued, and the battery cell voltage at the current time is acquired again. In this example, a first voltage CV 1 4150mV of first charging current CC 1 2000mA, a second charging current CC 2 Measuring the second voltage CV after pulse charging to 100mA 2 The data is taken into the formula to calculate the impedance value of the battery.
Further, the calculating the current impedance value of the battery according to the charging data includes:
calculating a voltage difference between the first voltage and the second voltage, and calculating a current difference between the first charging current and the second charging current;
and calculating the ratio between the voltage difference and the current difference, and determining the ratio as the current impedance value.
Illustratively, during battery charging, the batteryThe power in the capacitor is increased, and the voltage is increased gradually, so that the second voltage CV 2 Is greater than the first voltage CV 1 Second voltage CV 2 Reducing the first voltage CV 1 Obtaining a voltage difference; after pulse charging, the charging current suddenly decreases, and thus the first charging current CC 1 Is greater than the second charging current CC 2 First charging current CC 1 Reducing the second charging current CC 2 The current difference is calculated, the present impedance value is the ratio between the voltage difference and the current difference, i.e. the present impedance value is (CV 2 -CV 1 )/(CC 1 -CC 2 )。
Further, the impedance relation is generated by:
when the battery meets the charging condition, charging the test battery at a plurality of test temperatures, and obtaining charging test data, wherein the charging test data comprises a first test voltage and a corresponding first test charging current, and a second test voltage and a corresponding second test charging current;
calculating a plurality of battery impedance values of the test battery according to the first test voltage, the first test charging current, the second test voltage and the second test charging current corresponding to a plurality of test temperatures;
the impedance relationship is derived based on a plurality of battery impedance values and their corresponding test temperatures.
Illustratively, the impedance value of the battery may change with temperature changes. And at each temperature value, calculating a corresponding impedance value through charging data, and then fitting an impedance relation of the battery according to a plurality of groups of impedance values and temperature values. And further, a preset mathematical algorithm can be used for normalizing the measured impedance value to a corresponding current impedance value at a preset temperature value.
For example, the impedance relationship may be calculated according to the following equation:
IMP＝a*T 3 +b*T 2 +c*T+d,
where IMP represents the battery impedance value at a test temperature T, T represents the test temperature, and a, b, c, and d are coefficients to be calculated.
Since the equation has a plurality of coefficients to be calculated, it is necessary to acquire test data at a plurality of temperatures and then fit the impedance relation.
For example, table 1 is a temperature-impedance data table obtained by testing, and fig. 2 is a graph of an impedance relation provided in an embodiment of the present invention. The graph of fig. 2 is obtained after curve fitting the data in table 1.
Table 1 temperature-impedance data sheet
| Temp | 5.00 | 10.00 | 15.00 | 20.00 | 25.00 | 30.00 | 35.00 | 40.00 |
| Sample1 Imp | 143.00 | 111.22 | 87.17 | 70.77 | 52.79 | 51.02 | 46.39 | 42.50 |
| Sample2 Imp | 143.10 | 111.08 | 86.88 | 70.12 | 52.54 | 50.56 | 46.04 | 42.15 |
| Avgimp 12 | 143.05 | 111.15 | 87.03 | 70.44 | 52.67 | 50.79 | 46.21 | 42.32 |
In table 1, temp represents the charge temperature of the battery, sample1 Imp represents the current impedance value of Sample1, sample2 Imp represents the current impedance value of Sample2, and Avgimp 12 represents the average current impedance value of Sample1 and Sample 2.
Taking table 1 as an example, the battery is tested to obtain an impedance relation under a preset touch power voltage before the new battery is manufactured. The relation to be solved in the scheme is determined according to practical experience, the test is required to be carried out under at least 3 temperature values, the impedance value of the battery is calculated respectively, and a specific relation is calculated according to 3 groups of temperature-impedance value data. In table 1, in order to improve fitting accuracy, data of a plurality of test temperatures were collected, respectively: 5.00, 10.00, 15.00, 20.00, 25.00, 30.00, 35.00 and 40.00. Two impedance values Sample1 Imp and Sample2 Imp were calculated for each temperature, and the two impedance values were averaged to obtain an average value Avgimp.
The calculated impedance relation is:
y＝-0.2294x 3 +5.7201x 2 -49.277x+188.72，
i.e. imp= -0.2294T 3 +5.7201T 2 -49.277T+188.72，
Where IMP represents the battery impedance value at the test temperature T, and T represents the test temperature.
In the impedance relation, a= -0.2294, b= 5.7201, c= -49.277, d= 188.72, where the value of d is the resistance of the battery at 0 ℃. Assuming a reference temperature of 25 ℃, bringing t=25 ℃ into the formula yields the impedance value of the new battery at the reference temperature.
Further, the updating the compensation impedance value of the battery in the current state according to the reference impedance value includes:
acquiring an initial impedance value of the battery at the reference temperature when the battery is not in use;
calculating a charging impedance change rate according to the reference impedance value and the initial impedance value;
the compensation impedance value is calculated based on the reference impedance value and the charging impedance change rate.
For example, an initial impedance value of a new cell at a reference temperature (for example, 25 ℃) is recorded in a fuel gauge chip of the battery, the impedance value changes after the battery ages, an impedance change rate at the time of charging is calculated from the reference impedance value and the initial impedance value, and a compensation impedance value at the time of discharging at 7% is calculated from the impedance change rate.
Further, the calculating the charging impedance change rate from the reference impedance value and the initial impedance value includes:
calculating the charging impedance change rate according to the following formula:
D R ＝(R2-R1)/R1，
wherein D is R And R1 represents the initial impedance value, and R2 represents the reference impedance value.
For example, R1 is calculated from data obtained by a charging test, and R2 is calculated from data obtained by charging in a battery usage state, so the above formula calculates a charging impedance change rate, which characterizes the magnitude of impedance change of an aged battery compared to a new battery.
Further, the calculating the compensation impedance value based on the reference impedance value, the charging impedance change rate includes:
calculating the compensation impedance value according to the following formula:
R0＝R1*(1+n*D R )，
wherein R0 represents the compensation impedance value, R1 represents the reference impedance value, D R And n represents a conversion coefficient of the charging impedance change rate and the discharging impedance change rate.
Illustratively, when the FCC accuracy is updated by using the CEDV algorithm, the impedance in the process is calculated as the impedance of the battery discharge, and therefore, the charging impedance change rate needs to be multiplied by the coefficient n and then converted into the discharge impedance change rate, so that the compensation impedance value when the battery discharge is 7% is calculated.
The technical scheme and technical effects of the scheme are specifically described below according to data.
Table 2 charging impedance test results
In table 2, ATL475778 represents a battery cell model, ED650 represents a battery energy density of 650, CHG DCR represents a battery impedance value during charging, fresh CHG represents an initial impedance value of a new battery, aging CHG represents a reference impedance value of the battery after Aging, and growth rate represents a charging impedance change rate.
Table 2 shows the results of the charge impedance test, in Table 2, the initial impedance value R1 of the new battery is 59.34mΩ, according to the method of the present embodimentCalculating the reference impedance value R2 of the aged battery to 74.37mΩ, and further calculating the charging impedance change rate D according to the above formula R 25.33%.
TABLE 3 discharge impedance test results
In table 3, in table 2, ATL475778 represents a cell model number, ED650 represents a battery energy density of 650, chg DCR represents a battery resistance value during charging, discharge current represents a discharge current, fresh DSG represents a discharge resistance value of a new battery, aging DSG represents a compensation resistance value of a battery after Aging, and growth rate represents a discharge resistance change rate.
Table 3 shows the discharge impedance test results, and in table 3, taking the first group of data as an example, the negative sign "-" in the discharge rate indicates discharge, when the discharge rate is 0.2C, the discharge impedance value of the new battery is 92.81mΩ, the compensation impedance value R0 of the aged battery is 74.37mΩ, and the discharge impedance change rate is 24.95%.
In the above-described group 1 data, the discharge magnification was 0.2C, and the conversion coefficient n1 of the charge impedance change rate and the discharge impedance change rate was 24.95/25.33= 98.52%;
in the above-described group 2 data, the discharge magnification was 0.5C, and the conversion coefficient n2 of the charge impedance change rate and the discharge impedance change rate was 24.95/25.33= 76.63%;
in the above data of group 3, the discharge magnification was 1C, and the conversion coefficient n3 of the charge resistance change rate and the discharge resistance change rate was 24.95/25.33= 60.65%.
Table 4 FCC without compensation
In table 4, ATL475778 indicates a cell model, ED650 indicates a battery energy density of 650, VSQ at 45 ℃ indicates a long-cycle test at 45 ℃,200 cycles indicates a cycle number of 200 times, sample indicates a Sample, condition indicates a charging Condition, "Before r0=1884" indicates an R0 value Before compensation, real cap (mAh) indicates a Real battery capacity, FCC/cWh indicates a full charge capacity, cWh indicates a capacity unit, FCC/mAh indicates a full charge capacity, mAh indicates a capacity unit, FCC accuracies indicates a battery capacity deviation (accuracy of full charge capacity).
Table 4 shows the FCC calculated without compensating the battery impedance value in the prior art, and the compensated impedance value R0 is a fixed value set when the battery leaves the factory, that is, an initial value. As shown in table 4, the charging conditions were: the charging temperature was 25 ℃, and the charging rates were 0.2C, 0.5C, and 1C, respectively, and were tested 2 times under each charging condition in order to improve the calculation accuracy. Real cap (mAh) is the actual battery capacity, and FCC/cWh and FCC/mAh are the FCC with different estimated capacity units. Comparing the actual battery capacity in mAh with the estimated battery capacity, a battery capacity deviation FCC accuracy is obtained, and it can be seen from table 4 that if FCC is calculated from a fixed impedance value, the deviation is large, in the example, the deviation is all greater than 10%, and the actual battery capacity is actually greater than the estimated battery capacity.
TABLE 5 FCC after compensation
In table 5, sample indicates a Sample, condition indicates a charging Condition, "After r0=2354" indicates an R0 value After compensation, real cap (mAh) indicates a Real battery capacity, FCC/cWh indicates a full charge capacity, cWh indicates a capacity unit, FCC/mAh indicates a full charge capacity, mAh indicates a capacity unit, and FCC accuracy indicates a battery capacity deviation (accuracy of full charge capacity).
Table 5 shows that the calculated compensation impedance value is different when the battery temperature and the charging rate are different for the FCC after compensation. Thus, the supplementary resistance values at a charging temperature of 25℃and charging rates of 0.2C, 0.5C and 1C were calculated, respectively. Taking the example when the charging rate is 0.2C, the deviation between the Real battery capacity Real cap (mAh) and the compensated battery capacity FCC/mAh is obviously reduced, and the scheme improves the updating precision of FCC by calculating the accurate compensation impedance value.
Through one or more of the above embodiments of the present invention, at least the following technical effects can be achieved:
in the technical scheme disclosed by the invention, a plurality of conditions are preset in advance, when the current state of the battery meets the charging conditions, the current impedance value of the battery is calculated according to the obtained charging data, so that a reference impedance value at a preset temperature is obtained, and then the compensation impedance value for calculating the battery capacity is updated according to the reference impedance value, so that the accurate battery capacity is calculated. According to the scheme, an additional circuit is not needed, corresponding parameters can be optimized through a single aging cycle test, required data are obtained in the battery charging process, the actual impedance value of the battery is calculated, and the operation is easy. The calculated accurate supplementary impedance value replaces the fixed impedance value to calculate the FCC, so that the problem of insufficient FCC precision after the battery is stored for a long time and aged is solved, and the accurate update of the FCC is realized.
Based on the same inventive concept as a battery capacity updating method according to an embodiment of the present invention, an embodiment of the present invention provides a battery capacity updating device, please refer to fig. 3, which includes:
a first calculation module 201, configured to, when it is determined that a battery meets a preset charging condition, charge the battery and obtain charging data, and calculate a current impedance value of the battery according to the charging data;
a second calculation module 202, configured to obtain a reference impedance value of the battery at a reference temperature according to the current impedance value and a pre-generated impedance relational expression;
and the battery capacity updating module 203 is configured to update a compensation impedance value of the battery in a current state according to the reference impedance value, and update a battery capacity of the battery according to the compensation impedance value.
Further, the first computing module 201 is further configured to:
acquiring the charging current multiplying power, the charging temperature and the current voltage value of the battery;
determining that the charging current multiplying power is in a preset multiplying power interval, determining that the charging temperature is in a preset temperature interval, and determining that the current voltage value is a preset first voltage.
Further, the first computing module 201 is further configured to:
when the current voltage value of the battery is the first voltage, changing the charging current from a first charging current to a second charging current, changing the charging current from the second charging current to the first charging current after the charging time reaches a preset time, and determining that the current voltage value of the battery is the second voltage.
Further, the first computing module 201 is further configured to:
calculating a voltage difference between the first voltage and the second voltage;
calculating a current difference between the first charging current and the second charging current;
and calculating the ratio between the voltage difference and the current difference, and determining the ratio as the current impedance value.
Further, the battery capacity update module 203 is further configured to:
acquiring an initial impedance value of the battery at the reference temperature when the battery is not in use;
calculating a charging impedance change rate according to the reference impedance value and the initial impedance value;
the compensation impedance value is calculated based on the reference impedance value and the charging impedance change rate.
Further, the battery capacity update module 203 is further configured to:
calculating the charging impedance change rate according to the following formula:
D R ＝(R2-R1)/R1，
wherein D is R And R1 represents the initial impedance value, and R2 represents the reference impedance value.
Further, the battery capacity update module 203 is further configured to:
calculating the compensation impedance value according to the following formula:
R0＝R1*(1+n*D R )，
wherein R0 represents the compensation impedance value, R1 represents the reference impedance value, D R And n represents a conversion coefficient of the charging impedance change rate and the discharging impedance change rate.
Other aspects and implementation details of the battery capacity updating device are the same as or similar to those of the battery capacity updating method described above, and are not described herein.
According to another aspect of the present invention, there is also provided a storage medium having stored therein a plurality of instructions adapted to be loaded by a processor to perform any of the battery capacity updating methods as described above.
In summary, although the present invention has been described in terms of the preferred embodiments, the preferred embodiments are not limited to the above embodiments, and various modifications and changes can be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention is defined by the appended claims.
Claims (11)
1. A battery capacity updating method, the method comprising:
when the battery is determined to meet the preset charging condition, charging the battery and acquiring charging data, and calculating the current impedance value of the battery according to the charging data;
obtaining a reference impedance value of the battery at a reference temperature according to the current impedance value and a pre-generated impedance relational expression;
and updating the compensation impedance value of the battery in the current state according to the reference impedance value, and updating the battery capacity of the battery according to the compensation impedance value.
2. The method of claim 1, wherein determining that the battery meets a preset charging condition comprises:
acquiring the charging current multiplying power, the charging temperature and the current voltage value of the battery;
determining that the charging current multiplying power is in a preset multiplying power interval, determining that the charging temperature is in a preset temperature interval, and determining that the current voltage value is a preset first voltage.
3. The method of claim 2, wherein charging the battery and obtaining charging data comprises:
when the current voltage value of the battery is the first voltage, changing the charging current from the first charging current to the second charging current, and after the charging time reaches the preset time, changing the charging current from the second charging current to the first charging current, and determining the current voltage value of the battery to be the second voltage.
4. The method of claim 3, wherein said calculating a current impedance value of the battery from the charge data comprises:
calculating a voltage difference between the first voltage and the second voltage, and calculating a current difference between the first charging current and the second charging current;
and calculating the ratio between the voltage difference and the current difference, and determining the ratio as the current impedance value.
5. The method of claim 1, wherein the impedance relationship is generated by:
when the battery meets the charging condition, charging the test battery at a plurality of test temperatures, and obtaining charging test data, wherein the charging test data comprises a first test voltage and a corresponding first test charging current, and a second test voltage and a corresponding second test charging current;
calculating a plurality of battery impedance values of the test battery according to the first test voltage, the first test charging current, the second test voltage and the second test charging current corresponding to a plurality of test temperatures;
the impedance relationship is derived based on a plurality of battery impedance values and their corresponding test temperatures.
6. The method of claim 1, wherein updating the compensation impedance value of the battery in the current state based on the reference impedance value comprises:
acquiring an initial impedance value of the battery at the reference temperature when the battery is not in use;
calculating a charging impedance change rate according to the reference impedance value and the initial impedance value;
the compensation impedance value is calculated based on the reference impedance value and the charging impedance change rate.
7. The method of claim 6, wherein said calculating a charge impedance rate of change from said reference impedance value and said initial impedance value comprises:
calculating the charging impedance change rate according to the following formula:
D R ＝(R2-R1)/R1，
wherein D is R And R1 represents the initial impedance value, and R2 represents the reference impedance value.
8. The method of claim 7, wherein the calculating the compensation impedance value based on the reference impedance value, the charging impedance rate of change comprises:
calculating the compensation impedance value according to the following formula:
R0＝R1*(1+n*D R )，
wherein R0 represents the compensation impedance value, and R1 represents theReference impedance value D R And n represents a conversion coefficient of the charging impedance change rate and the discharging impedance change rate.
9. A battery capacity updating apparatus, characterized in that the apparatus comprises:
the first calculation module is used for charging the battery and acquiring charging data when the battery is determined to meet preset charging conditions, and calculating the current impedance value of the battery according to the charging data;
the second calculation module is used for obtaining a reference impedance value of the battery at a reference temperature according to the current impedance value and a pre-generated impedance relational expression;
and the battery capacity updating module is used for updating the compensation impedance value of the battery in the current state according to the reference impedance value and updating the battery capacity of the battery according to the compensation impedance value.
10. An electronic device, comprising: the device comprises a controller, a communication interface, a memory and a communication bus, wherein the controller, the communication interface and the memory are communicated with each other through the communication bus;
a memory for storing a computer program;
a controller for executing a program stored on a memory to implement the battery capacity updating method according to any one of claims 1 to 8.
11. A storage medium having stored therein a plurality of instructions adapted to be loaded by a processor to perform the method of any one of claims 1 to 8.
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