CN116203428A - Self-discharge detection method for calculating equivalent model parameters of lithium battery based on constant-voltage charging and discharging - Google Patents
Self-discharge detection method for calculating equivalent model parameters of lithium battery based on constant-voltage charging and discharging Download PDFInfo
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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]
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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]
- G01R31/378—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC] specially adapted for the type of battery or accumulator
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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]
- G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
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Abstract
The invention discloses a self-discharge detection method for calculating parameters of an equivalent model of a lithium battery based on constant-voltage charging, which comprises the following steps: s1, constructing a self-discharge equivalent circuit model and a self-discharge current mathematical model of a lithium ion battery; s2, measuring the open-circuit voltage of the battery by using a universal meter; s3, measuring a relation curve of the state of charge of the battery and the open-circuit voltage to obtain an equivalent capacitance corresponding to the current state of charge; s4, measuring self-discharge resistance: applying a programmable constant voltage source to two ends of the battery, and connecting the two ends through a current detection resistor; monitoring real-time line current, and obtaining a self-discharge resistor according to the mathematical relationship between the self-discharge resistor and the line current; s5, substituting the parameters measured in the S2-S4 into a self-discharge current mathematical model to obtain the self-discharge current. When the self-discharge equivalent model parameters are measured, the invention does not need to wait for the line current to reach stability, and can effectively shorten the measurement time by utilizing the process quantity to calculate the self-discharge resistance.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a self-discharge detection method for calculating equivalent model parameters of a lithium battery based on constant-voltage charging and electrolysis.
Background
With the increasing importance of the international society to the energy crisis, the environmental pollution problem and the like, the lithium ion battery is widely applied as a pollution-free, high in energy density, long in service life and the like; currently, lithium ion batteries are widely used in electronic products such as mobile phones, watches, cameras, children toys, and the like.
In the new energy automobile industry, a power battery system formed by lithium ion batteries provides driving electric energy for the new energy automobile, and is one of the most critical parts of the new energy automobile; and the power battery system requires that each single battery has high consistency in capacity, internal resistance, voltage, self-discharge and the like.
The self-discharge of the battery not only can influence the capacity of the single battery, but also can influence the consistency of a power system of the lithium ion battery, and further influence the performance and the service life of the new energy automobile, so that the self-discharge measurement is an important detection technology for the quality assurance of the power battery system.
The self-discharge of the battery means that the battery is not connected with an external circuit, and the capacity loss is caused by self-reaction in the battery; self-discharge can be classified into reversible self-discharge and irreversible self-discharge. The reversible self-discharge is caused by the fact that impurities exist in the battery to pierce through the diaphragm, electrons penetrate through the diaphragm to form an internal short circuit, and the reversible self-discharge also becomes physical self-discharge. The self-discharge caused by the micro-short circuit has a great influence on the long-term performance of the battery; the irreversible self-discharge is caused by chemical side reaction inside the battery, the anode and cathode materials and some impurities of the battery can generate chemical side reaction with the electrolyte of the battery, so that lithium ions are lost, capacity loss is directly caused, the irreversible self-discharge is chemical self-discharge, and the irreversible self-discharge of the battery is screened by adopting a high-temperature storage accelerating chemical side reaction mode. Reversible self-discharge has a greater impact on the long-term performance of the battery than irreversible self-discharge.
Currently, common self-discharge detection methods include a direct measurement method, an open circuit voltage method, and a capacity retention method.
The direct measurement method comprises charging the battery to obtain the current capacity Q of the battery 0 Then standing for a period of time at normal temperature, wherein the standing time specified by China national Standard for Power storage Battery Performance requirement and test method for electric automobile (GB/T31486) is 28 days, and then charging the Battery at normal temperature to obtain the capacity Q after standing 1 It can be found that the self-discharge rate of the lithium ion battery is (Q 0 -Q 1 )/Q 0 The method comprises the steps of carrying out a first treatment on the surface of the Charging the battery, discharging all the electric quantity to obtain battery capacity Q 2 The method comprises the steps of carrying out a first treatment on the surface of the The reversible self-discharge of the battery is Q rev ＝Q 2 -Q 1 The method comprises the steps of carrying out a first treatment on the surface of the Irreversible self-discharge to Q irr ＝Q 0 -Q 2 。
The open circuit voltage method is based on the unique correspondence between the open circuit voltage OCV of the battery and the state of charge of the battery, and the open circuit voltage loss is used for representing the electric quantity loss of the battery. Measuring open circuit voltage OCV of battery before standing using multimeter 1 Standing at normal temperature for a period of time t, wherein the standing time specified by a general enterprise is 2-10 days, and then measuring the open circuit voltage OCV of the battery after standing 2 The method comprises the steps of carrying out a first treatment on the surface of the The evaluation index of the open circuit voltage method is K, which means that the open circuit voltage in unit time is reduced
K＝(OCV 1 -OCV 2 )/t。
The capacity retention method is an equivalent circuit model in which a battery is equivalent to a capacitor, an internal resistance, and a self-discharge resistance, and a mathematical model of the self-discharge current of the battery can be estimated from the circuit model. Applying a programmable constant voltage source to the battery, wherein the voltage of the programmable constant voltage source is equal to or close to the open-circuit voltage of the battery as much as possible, and the constant voltage source is used for carrying out tiny current charging on the battery until the charging current and the battery terminal voltage are stable, and the charging current mathematical model and the self-discharging current mathematical model are consistent when the charging current and the battery terminal voltage are stable, so that the charging current just can supplement the internal self-discharging current loss of the battery, namely, the current is equal to the self-discharging current; the charging current is monitored and read by using a multimeter and other devices, and a stable measurement result is taken as the final value of the self-discharging current.
The three measuring methods have high measuring precision by a direct measuring method, but the measuring time is longest, and one month of standing time is needed; the open circuit voltage method utilizes the advantage of high resolution of the universal meter, shortens the test time to within a few days, but the measurement time is still very long; the capacity retention method directly measures the capacity loss in unit time, namely the self-discharge current; the test time of the method is determined by the time constant of the test loop, and after three times of time constant, the change of the self-discharge current is smaller than 5% of the final value, so that the self-discharge current can be considered to be stable. However, since the final value of the self-discharge current is an unknown parameter, a test time greater than three times the time constant is generally required to determine that the self-discharge current has reached stability, the waiting time is uncertain, and the time is long.
Disclosure of Invention
The invention aims to solve the problems of low efficiency and long test time of the self-discharge test method in the prior art, and provides a self-discharge detection method based on constant-voltage charge and calculation of lithium battery equivalent model parameters, which is capable of measuring parameters such as open-circuit voltage, equivalent capacitance and self-discharge resistance of a battery by respectively utilizing a universal meter, an open-circuit voltage curve of the battery and constant-voltage charge line current in an established measurement loop, and substituting the parameters into a mathematical model to obtain the self-discharge current.
The aim of the invention is realized by the following technical scheme: the self-discharge detection method for calculating the equivalent model parameters of the lithium battery based on constant-voltage charging and electrolysis comprises the following steps:
s1, constructing a lithium ion battery equivalent circuit model and a self-discharge current mathematical model: the battery equivalent circuit model comprises an equivalent capacitor C eff Self-discharge resistor R sd And internal resistance R S Equivalent capacitance C eff And self-discharge resistor R sd Parallel connection with internal resistance R S In the series connection and open circuit state, the voltage across the series circuit is the open circuit voltage OCV, and the battery self-discharge current I sd The mathematical model of (a) is:
s2, measuring the open circuit voltage OCV of the battery by using a universal meter;
s3, measuring a relation curve of the charge state and the open-circuit voltage of the battery to obtain an equivalent capacitance C corresponding to the current charge state eff ；
S4, measuring self-discharge resistance R sd : a programmable constant voltage source is applied to two ends of the battery, and a current detection resistor R is arranged between the two ends line Connecting; through voltmeter and current detection resistor R line Monitoring real-time line current I m And according to the self-discharge resistance R sd And line current I m Mathematical relationship between the two to obtain self-discharge resistance R sd ；
S5, equivalent capacitance C corresponding to the current state of charge and the open circuit voltage OCV measured by S2-S4 eff Self-discharge resistor R sd Substituting into the formula (1) to obtain the self-discharge current I of the battery sd Mathematical model over time.
The specific implementation method of the step S3 is as follows:
s31, charging the battery to an upper cut-off voltage by using a constant current of 1C, and then turning to constant voltage charging until the current is less than 0.05C, and stopping charging;
s32, discharging to lower cut-off voltage by using a 1C current constant current, and measuring the battery capacity Q;
s33, charging the battery to an upper cut-off voltage by using a constant current of 1C, and then turning to constant voltage charging until the current is less than 0.05C to stop charging;
s34, the measurement area of the charge state is 5% -95%, the charge state interval of 10% -90% of the segments is set to be 5%, the rest charge state interval is set to be 1%, and the total charge state interval is 27 points; discharging at 1C, calculating discharge time according to the state of charge, and measuring the open circuit voltage of the battery after standing for 2 hours when discharging to one state of charge measuring point; repeating the discharging process until all points are measured;
s35, after measurement is completed, performing three hermit interpolation on points in a 10% -90% state of charge interval to improve resolution, enabling the state of charge interval to be 1%, and obtaining a relation curve of the state of charge and open circuit voltage of the battery; the method comprises the steps of carrying out a first treatment on the surface of the Then according to the open circuit voltage curve of the battery and the formula (2), the equivalent capacitance under the current state of charge is obtained;
the Δq is a capacity of the battery discharged by Δsoc corresponding to the total capacity discharged in the current state of charge, and may be obtained from the state of charge interval Δsoc and the total capacity Q on a relationship curve of the state of charge and the open circuit voltage; delta V is the difference between the initial open circuit voltage and the discharged open circuit voltage after the battery discharges the delta SOC of the total capacity under the current state of charge, namely delta OCV, and can be obtained from the relation curve of the state of charge and the open circuit voltage.
In the step S4, the self-discharge resistance R is measured sd The required equipment comprises a programmable constant voltage source, two seven-bit half-digital universal meters, a current detection resistor, constant temperature equipment and an upper computer; the constant temperature equipment is used for eliminating the influence of temperature measurement and test, and the upper computer is used for control, acquisition and operation; universal meter 1 is used for measuring the voltage at two ends of a programmable constant voltage source, and universal meter 2 is used for measuring the voltage V at two ends of a battery to be measured cell The current detecting resistor is positioned at the two ends of the programmable constant voltage source and the battery, and then the line current I m The measurement model of (2) is shown in formula (3).
In measuring self-discharge resistance R sd Before, the battery to be tested is placed in constant temperature equipment for standing for one day, so that the polarization phenomenon of the battery is removed, and the voltage of the battery is fully stabilized; the universal meter 1 is connected with the programmable constant voltage source, the universal meter 2 is connected with the battery, the universal meter 2 measures the current open-circuit voltage OCV of the battery and sets the current open-circuit voltage OCV as the input voltage of the programmable constant voltage source, and the current open-circuit voltage OCV is constant due to the programmable constant voltage sourceThe voltage source has output error, so the output voltage V of the programmable constant voltage source needs to be fed back according to the universal meter 1 s o urce The difference between the open-circuit voltage OCV of the battery fed back by the universal meter 2 and the input of the programmable constant voltage source is regulated, and the voltage V output by the programmable constant voltage source is repeated for a plurality of times s o urce The difference between the open-circuit voltage OCV of the battery to be tested and the open-circuit voltage OCV of the battery to be tested is less than 5 microvolts, so that the open-circuit voltage OCV and the open-circuit voltage OCV of the battery to be tested are matched; connecting a measuring circuit, and obtaining real-time line current I through a universal meter and a formula (3) m The method comprises the steps of carrying out a first treatment on the surface of the Due to the internal resistance R of the battery S Is far smaller than the current detection resistance R line Therefore, the internal resistance R of the battery can be ignored S From the influence of (a) the self-discharge resistance R can be obtained from the measuring circuit sd And real-time line current I m The mathematical relationship between the two is shown as formula (4), and the upper computer obtains the self-discharge resistor R according to formula (4) sd ；
If the self-discharge resistance R is obtained sd At one time constant R of measuring circuit line C eff The self-discharge resistance R is considered to be if the variation value is less than 5% sd Has reached stability, taking its mean value over the period of time as self-discharge resistance R sd Is a final measurement of (a).
The beneficial effects of the invention are as follows: according to the method, the self-discharge equivalent circuit model and the self-discharge current mathematical model of the lithium ion battery are built, the open-circuit voltage, the equivalent capacitance and the self-discharge resistance of the battery are obtained by respectively utilizing the universal meter, the open-circuit voltage curve of the battery and the process current in the built measuring loop, and then the open-circuit voltage, the equivalent capacitance and the self-discharge resistance are substituted into the self-discharge current mathematical model to obtain the self-discharge current. Compared with the traditional direct measurement method, open-circuit voltage method and capacity retention method, the method greatly shortens the self-discharge measurement time and improves the measurement efficiency.
Drawings
FIG. 1 is a measurement flow chart of the self-discharge detection method of the present invention;
FIG. 2 is a schematic diagram of the self-discharge detection method of the present invention;
FIG. 3 is a schematic diagram of a battery state of charge versus open circuit voltage;
fig. 4 is a schematic diagram of a measurement principle of a model parameter self-discharge resistance of a battery.
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings.
As shown in fig. 1, the self-discharge detection method based on constant-voltage charging and lithium battery equivalent model parameters comprises the following steps:
s1, constructing a lithium ion battery equivalent circuit model and a self-discharge current mathematical model: according to the self-discharge characteristic of the lithium ion battery, an equivalent model of the lithium ion battery is constructed as shown in a dotted line frame in fig. 2, and the model comprises an equivalent capacitor C eff Self-discharge resistor R sd And internal resistance R S Equivalent capacitance C eff And self-discharge resistor R sd Parallel connection with internal resistance R S In the series connection and open circuit state, the voltage across the series circuit is the open circuit voltage OCV, and the battery self-discharge current I sd The mathematical model of (a) is:
s2, measuring the open circuit voltage OCV of the battery by using a universal meter;
s3, measuring a relation curve of the charge state and the open-circuit voltage of the battery to obtain an equivalent capacitance C corresponding to the current charge state eff The method comprises the steps of carrying out a first treatment on the surface of the The specific implementation method comprises the following steps:
s31, charging the battery, namely, charging the battery to an upper cut-off voltage by using a constant current of 1C (1 hour rate discharge current), and then turning to constant voltage charging until the current is less than 0.05C, and stopping charging;
s32, discharging to lower cut-off voltage by using a 1C current constant current, and measuring the battery capacity Q;
s33, charging the battery to an upper cut-off voltage by using a constant current of 1C, and then turning to constant voltage charging until the current is less than 0.05C to stop charging;
s34, the measurement area of the charge state is 5% -95%, the charge state interval of 10% -90% of the segments is set to be 5%, the rest charge state interval is set to be 1%, and the total charge state interval is 27 points; discharging at 1C, calculating discharge time according to the state of charge, and measuring the open circuit voltage of the battery after standing for 2 hours when discharging to one state of charge measuring point; repeating the discharging process until all points are measured;
s35, after measurement is completed, performing hermit interpolation on the points in the 10% -90% state of charge interval for three times to improve the resolution, enabling the state of charge interval to be 1%, and obtaining a relation curve of the state of charge of the battery and open circuit voltage, as shown in FIG. 3; then according to the open circuit voltage curve of the battery and the formula (2), the equivalent capacitance under the current state of charge is obtained;
the Δq is a capacity of the battery discharged by Δsoc corresponding to the total capacity discharged in the current state of charge, and may be obtained from the state of charge interval Δsoc and the total capacity Q on a relationship curve of the state of charge and the open circuit voltage; delta V is the difference between the initial open circuit voltage and the discharged open circuit voltage after the battery discharges the delta SOC of the total capacity under the current state of charge, namely delta OCV, and can be obtained from the relation curve of the state of charge and the open circuit voltage.
S4, measuring self-discharge resistance R sd : a programmable constant voltage source is applied to two ends of the battery, and a current detection resistor R is arranged between the two ends line Connecting; through voltmeter and current detection resistor R line Monitoring real-time line current I m And according to the self-discharge resistance R sd And line current I m Mathematical relationship between the two to obtain self-discharge resistance R sd ；
The measuring device measures the self-discharge resistance R as shown in FIG. 4 sd The required equipment comprises a programmable constant voltage source, two seven-bit half-digital multimeter and a current detecting resistorThe constant temperature equipment and the upper computer; the constant temperature equipment is used for eliminating the influence of temperature measurement and test, and the upper computer is used for control, acquisition and operation; universal meter 1 is used for measuring the voltage at two ends of a programmable constant voltage source, and universal meter 2 is used for measuring the voltage V at two ends of a battery to be measured cell The current detecting resistor is positioned at the two ends of the programmable constant voltage source and the battery, and then the line current I m The measurement model of (2) is shown in formula (3).
In measuring self-discharge resistance R sd Before, the battery to be tested is placed in constant temperature equipment for standing for one day, so that the polarization phenomenon of the battery is removed, and the voltage of the battery is fully stabilized; the universal meter 1 is connected with the programmable constant voltage source, the universal meter 2 is connected with the battery, the universal meter 2 measures the current open-circuit voltage OCV of the battery and sets the current open-circuit voltage OCV as the input voltage of the programmable constant voltage source, and the output voltage V of the programmable constant voltage source needs to be fed back according to the universal meter 1 because the programmable constant voltage source has an output error s o urce The difference between the open-circuit voltage OCV of the battery fed back by the universal meter 2 and the input of the programmable constant voltage source is regulated, and the voltage V output by the programmable constant voltage source is repeated for a plurality of times s o urce The difference between the open-circuit voltage OCV of the battery to be tested and the open-circuit voltage OCV of the battery to be tested is less than 5 microvolts, so that the open-circuit voltage OCV and the open-circuit voltage OCV of the battery to be tested are matched; connecting a measuring circuit, and obtaining real-time line current I through a universal meter and a formula (3) m The current data is updated every 10 seconds; due to the internal resistance R of the battery S Is far smaller than the current detection resistance R line Therefore, the internal resistance R of the battery can be ignored S From the influence of (a) the self-discharge resistance R can be obtained from the measuring circuit sd And real-time line current I m The mathematical relationship between the two is shown as formula (4), and the upper computer obtains the self-discharge resistor R according to formula (4) sd ；
The upper computer generates voltage data according to each group of battery voltage and constant voltage source voltage dataCan measure a self-discharge resistance R sd I.e. a self-discharge resistance R can be obtained every 10 seconds sd But due to line current I m With measurement errors, the line current I at an initial stage m Smaller, larger relative error, self-discharge resistance R sd The measured value fluctuates greatly, and the line current I increases with time m Increase, decrease the relative error, self-discharge resistance R sd The measured value is more accurate and stable, if the self-discharge resistance R is obtained sd At one time constant R of measuring circuit line C eff A change value of less than 5% for about 3 to 4 hours, the self-discharge resistance R is considered to be sd Has reached stability, taking its mean value over the period of time as self-discharge resistance R sd Is a final measurement of (a).
S5, equivalent capacitance C corresponding to the current state of charge and the open circuit voltage OCV measured by S2-S4 eff Self-discharge resistor R sd Substituting into the formula (1) to obtain the self-discharge current I of the battery sd Mathematical model over time. Due to time constant R sd C eff For several tens of days, the time-dependent self-discharge current change is negligible within several hours of measurement, and OCV/R can be considered sd Is the self-discharge current of the battery at the present state of charge.
Those of ordinary skill in the art will recognize that the embodiments described herein are for the purpose of aiding the reader in understanding the principles of the present invention and should be understood that the scope of the invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific modifications and combinations from the teachings of the present disclosure without departing from the spirit thereof, and such modifications and combinations remain within the scope of the present disclosure.
Claims (3)
1. The self-discharge detection method for calculating the equivalent model parameters of the lithium battery based on constant-voltage charging and electrolysis is characterized by comprising the following steps of:
s1, constructing a lithium ion battery equivalent circuit model and a self-discharge current mathematical model: the battery equivalent circuit model comprises equivalent electricityCapacitor C eff Self-discharge resistor R sd And internal resistance R S Equivalent capacitance C eff And self-discharge resistor R sd Parallel connection with internal resistance R S In the series connection and open circuit state, the voltage across the series circuit is the open circuit voltage OCV, and the battery self-discharge current I sd The mathematical model of (a) is:
s2, measuring the open circuit voltage OCV of the battery by using a universal meter;
s3, measuring a relation curve of the charge state and the open-circuit voltage of the battery to obtain an equivalent capacitance C corresponding to the current charge state e ff；
S4, measuring self-discharge resistance R sd : a programmable constant voltage source is applied to two ends of the battery, and a current detection resistor R is arranged between the two ends line Connecting; through voltmeter and current detection resistor R line Monitoring real-time line current I m And according to the self-discharge resistance R sd And line current I m Mathematical relationship between the two to obtain self-discharge resistance R sd ；
S5, equivalent capacitance C corresponding to the current state of charge and the open circuit voltage OCV measured by S2-S4 eff Self-discharge resistor R sd Is carried into the formula (1) to obtain the self-discharge current I of the battery sd Mathematical model over time.
2. The self-discharge detection method based on constant-voltage charging calculation of the parameters of the equivalent model of the lithium battery according to claim 1, wherein the specific implementation method of the step S3 is as follows:
s31, charging the battery to an upper cut-off voltage by using a constant current of 1C, and then turning to constant voltage charging until the current is less than 0.05C, and stopping charging;
s32, discharging to lower cut-off voltage by using a 1C current constant current, and measuring the battery capacity Q;
s33, charging the battery to an upper cut-off voltage by using a constant current of 1C, and then turning to constant voltage charging until the current is less than 0.05C to stop charging;
s34, the measurement area of the charge state is 5% -95%, the charge state interval of 10% -90% of the segments is set to be 5%, the rest charge state interval is set to be 1%, and the total charge state interval is 27 points; discharging at 1C, calculating discharge time according to the state of charge, and measuring the open circuit voltage of the battery after standing for 2 hours when discharging to one state of charge measuring point; repeating the discharging process until all points are measured;
s35, after measurement is completed, performing three hermit interpolation on points in a 10% -90% state of charge interval to improve resolution, enabling the state of charge interval to be 1%, and obtaining a relation curve of the state of charge and open circuit voltage of the battery; then according to the open circuit voltage curve of the battery and the formula (2), the equivalent capacitance under the current state of charge is obtained;
the delta Q is the capacity of the battery corresponding to the delta SOC of the total discharge capacity under the current state of charge, and is obtained from the state of charge interval delta SOC and the total capacity Q on the relation curve of the state of charge and the open circuit voltage; delta V is the difference between the initial open circuit voltage and the discharged open circuit voltage after the battery discharges the delta SOC of the total capacity under the current state of charge, namely delta OCV, and is obtained from the relation curve of the state of charge and the open circuit voltage.
3. The method for detecting self-discharge based on constant-voltage charge and discharge calculation of parameters of equivalent model of lithium battery according to claim 1, wherein in step S4, self-discharge resistance R is measured sd The required equipment comprises a programmable constant voltage source, two seven-bit half-digital universal meters, a current detection resistor, constant temperature equipment and an upper computer; the constant temperature equipment is used for eliminating the influence of temperature measurement and test, and the upper computer is used for control, acquisition and operation; universal meter 1 for measuring voltage V across programmable constant voltage source s o urce The universal meter 2 is used for measuring the voltage V at two ends of the battery to be measured cell The current detecting resistor is positioned on the programmable constant voltage sourceAnd the two ends of the battery are connected with the line current I m The measurement model of (2) is shown in formula (3):
in measuring self-discharge resistance R sd Before, the battery to be tested is placed in constant temperature equipment for standing for one day, so that the polarization phenomenon of the battery is removed, and the voltage of the battery is fully stabilized; the universal meter 1 is connected with the programmable constant voltage source, the universal meter 2 is connected with the battery, the universal meter 2 measures the current open-circuit voltage OCV of the battery and sets the current open-circuit voltage OCV as the input voltage of the programmable constant voltage source, and the output voltage V of the programmable constant voltage source needs to be fed back according to the universal meter 1 because the programmable constant voltage source has an output error s o urce The difference between the open-circuit voltage OCV of the battery fed back by the universal meter 2 and the input of the programmable constant voltage source is regulated, and the voltage V output by the programmable constant voltage source is repeated for a plurality of times s o urce The difference between the open-circuit voltage OCV of the battery to be tested and the open-circuit voltage OCV of the battery to be tested is less than 5 microvolts, so that the open-circuit voltage OCV and the open-circuit voltage OCV of the battery to be tested are matched; connecting a measuring circuit, and obtaining real-time line current I through a universal meter and a formula (3) m The method comprises the steps of carrying out a first treatment on the surface of the Due to the internal resistance R of the battery S Is far smaller than the current detection resistance R line Therefore, the internal resistance R of the battery can be ignored S From the influence of (a) the self-discharge resistance R can be obtained from the measuring circuit sd And real-time line current I m The mathematical relationship between the two is shown as formula (4), and the upper computer obtains the self-discharge resistor R according to formula (4) sd ；
If the self-discharge resistance R is obtained sd At one time constant R of measuring circuit line C eff The self-discharge resistance R is considered to be if the variation value is less than 5% sd Has reached stability, taking its mean value over the period of time as self-discharge resistance R sd Is a final measurement of (a).
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116500466A (en) * | 2023-06-28 | 2023-07-28 | 吉林大学 | LXI bus-based integrated battery parameter measurement system and method |
| CN117148172A (en) * | 2023-10-31 | 2023-12-01 | 宁德时代新能源科技股份有限公司 | Battery state detection method, device, computing equipment and medium |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116500466A (en) * | 2023-06-28 | 2023-07-28 | 吉林大学 | LXI bus-based integrated battery parameter measurement system and method |
| CN116500466B (en) * | 2023-06-28 | 2023-09-15 | 吉林大学 | LXI bus-based integrated battery parameter measurement system and method |
| CN117148172A (en) * | 2023-10-31 | 2023-12-01 | 宁德时代新能源科技股份有限公司 | Battery state detection method, device, computing equipment and medium |
| CN117148172B (en) * | 2023-10-31 | 2024-04-09 | 宁德时代新能源科技股份有限公司 | Battery state detection method, device, computing equipment and medium |
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