CN117572268A - Method for detecting short circuit in power battery based on IC curve - Google Patents
Method for detecting short circuit in power battery based on IC curve Download PDFInfo
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- CN117572268A CN117572268A CN202311470094.4A CN202311470094A CN117572268A CN 117572268 A CN117572268 A CN 117572268A CN 202311470094 A CN202311470094 A CN 202311470094A CN 117572268 A CN117572268 A CN 117572268A
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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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- 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
- 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]
- G01R31/392—Determining battery ageing or deterioration, e.g. state of health
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Abstract
The invention discloses a method for detecting short circuit in a power battery based on an IC curve, which relates to the technical field of power batteries and comprises the following steps: calculating dq/dvi of each cell i in a charging process, drawing an IC curve, and calculating Euclidean distances between the cell i and other cells by using the IC curve envelope area Si of the cell i, the maximum value Mi of the IC curve, the charging starting voltage Vsi and the charging ending voltage Vei; calculating the distance and Di between the battery cell i and all other battery cells by using Euclidean distance between the battery cell i and other battery cells; and judging whether the battery cell i is an outlier or not according to the distance and Di of the battery cell i, and if so, indicating that the internal short circuit problem occurs. The invention comprehensively considers a plurality of characteristics based on the IC curve, including the envelope area of the IC curve and the maximum value of the IC curve of the battery core, is used for detecting the short circuit state in the power battery, and has relatively high detection accuracy.
Description
Technical Field
The invention relates to the technical field of power batteries, in particular to a method for detecting short circuits in a power battery based on an IC curve.
Background
The power battery is used as a core component of the new energy automobile and is directly related to safe and stable running of the automobile. In order to ensure good performance and prolong the service life of the battery, various parameters of the battery need to be effectively managed. Thermal runaway is one of the most dangerous factors in the use of power cells. According to the current research, the main factors causing thermal runaway can be classified into mechanical abuse, electrical abuse, thermal abuse. All three causes can lead to the direct contact of the anode and the cathode in the battery or the connection of the anode and the cathode through metal, so as to form internal short circuit. Internal short circuits are a common link in which three abuse modes lead to thermal runaway of the battery.
Therefore, the internal short circuit of the power battery can be timely and accurately detected, and various accidents can be effectively avoided.
In the prior art, the detection method of the short circuit in the battery mainly comprises the following steps: 1. the self-discharge of the battery at rest is detected. 2. And when in charge and discharge, the electric quantity predicted by the model is compared with the test electric quantity. 3. It is detected whether an abnormal dip-rise in the battery voltage signal occurs. 4. And checking consistency among the battery cells. 5. The battery temperature was detected using an infrared device.
At present, the method for detecting the short circuit in the battery is mainly carried out in a laboratory, and the detection methods 1-4 mentioned above cannot be used in actual vehicle operation and cannot be used for real-time online detection due to the problems of data acquisition frequency, acquisition precision and communication. Although the above-mentioned method 5 allows real-time on-line detection, it is too costly to install a sensor for each vehicle.
Through retrieval, the method for detecting the internal short circuit of the power battery on line is disclosed as CN115980596A, the method obtains the charging data of the vehicle battery on line, screens out the charging process that all the battery cells are completely charged, and calculates the internal short circuit degree value of each battery cell according to the charging data of the screened charging process; respectively judging the internal short circuit state of each cell according to the internal short circuit degree value of each cell; the patent uses the time difference that the voltage value of the electric core reaches the first near-cut-off voltage and the second near-cut-off voltage as the basis for judging the internal short circuit degree, and if the time difference that the voltage value of a certain electric core reaches the first near-cut-off voltage and the second near-cut-off voltage respectively is too large, namely exceeds the relative standard, the electric core is considered to be possibly internally short-circuited. However, when the patent judges the internal short-circuit degree of the battery cell, only the time difference between the first near-cut-off voltage and the second near-cut-off voltage is respectively reached according to the voltage value of the battery cell, only part of the characteristics of the battery cell can be reflected, the judging basis is not comprehensive, and the judging basis is not direct according to the time difference.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a method for detecting the short circuit in the power battery based on the IC curve, which comprehensively considers a plurality of characteristics based on the IC curve, including the envelope area of the IC curve of the battery core and the maximum value of the IC curve, is used for detecting the short circuit state in the power battery, and has relatively high detection accuracy.
In order to achieve the above purpose, the present invention adopts the following technical scheme, including:
a method for detecting a short circuit in a power battery based on an IC curve, comprising the steps of:
s4, calculating dq/dvi of each battery cell i in a charging process; wherein i=1, 2,3,; dvi the voltage change of the cell i between the front and rear data during charging; dq represents the charge quantity of the battery between the front and rear data in the charging process;
s5, drawing an IC curve according to dq/dvi of each cell i, and respectively calculating the envelope area Si of the IC curve of each cell i; wherein the abscissa represents the voltage value of the cell i, and the ordinate represents dq/dvi of the cell i;
s6, acquiring a charging start voltage Vsi, a charging end voltage Vei and an IC curve maximum value Mi of each battery cell i; where mi=max (dq/dvi);
s7, judging whether each cell i is an outlier: calculating Euclidean distances between the battery cell i and other battery cells by using the IC curve envelope area Si of the battery cell i, the maximum value Mi of the IC curve, the charging starting voltage Vsi and the charging ending voltage Vei; calculating the distance and Di between the battery cell i and all other battery cells by using Euclidean distance between the battery cell i and other battery cells; and judging whether the battery cell i is an outlier or not according to the distance and Di of the battery cell i, and if so, indicating that the internal short circuit problem occurs.
Preferably, the specific procedure of step S7 is as follows:
s71, calculating the Euclidean distance dij between the cell i and other cells, namely the cell j, as follows:
wherein j=1, 2,..n and j+.i, sj is the IC curve envelope area of cell j, vsj is the charge start voltage of cell j, vej is the charge end voltage of cell j, mj is the maximum value of dq/dvj of cell j;
s72, calculating the distance sum Di between the battery cell i and all other battery cells as follows:
Di＝∑ j dij
s73, according to the distances and Di of all the cells i, the calculated average Avg and standard deviation Std are respectively:
and S74, if the distance sum Di of the electric core i is Avg-alpha Std less than or equal to Di less than or equal to avg+alpha Std, the electric core i is not an outlier, otherwise, the electric core i is an outlier, namely the electric core i has the problem of internal short circuit.
Preferably, in step S7, normalization processing is performed on the IC curve envelope area Si, the IC curve maximum value Mi, the charging start voltage Vsi, and the charging end voltage Vei of the battery cell i, and the euclidean distance is calculated using the IC curve envelope area Si, the IC curve maximum value Mi, the charging start voltage Vsi, and the charging end voltage Vei of the battery cell i after normalization processing.
Preferably, the step S4 is preceded by the following steps:
s1, acquiring charging data of a vehicle on line, wherein the charging data comprise voltage values of all battery cores;
s2, splitting a charging process according to charging data of the vehicle, and if the time interval of the front and rear pieces of charging data is larger than a set value, determining that the front and rear pieces of charging data respectively belong to two different charging processes.
Preferably, the method further comprises:
and S3, cleaning charging data in a charging process, wherein in the charging process, if the same voltage value appears in the battery core repeatedly for 2 times or more than 2 times, only the charging data when the voltage value appears last time is reserved.
The invention has the advantages that:
(1) The invention comprehensively considers a plurality of characteristics, including the IC curve envelope area Si, the IC curve maximum value Mi, the charging initial voltage Vsi and the charging end voltage Vei of the battery core, is used for detecting the short circuit state in the power battery, and has relatively high detection accuracy. Compared with the prior art, the invention can more completely characterize the battery cell by taking the time difference that the voltage value of the battery cell reaches the first near-cut-off voltage and the second near-cut-off voltage as the basis for judging the internal short circuit degree, and improves the detection accuracy.
(2) The invention directly uses the online data to calculate the short circuit degree in the battery cell, has low realization cost and is easy to popularize.
(3) The invention quantifies the internal short circuit degree of the battery, so that the internal short circuit degree among different battery cells is easy to compare.
Drawings
Fig. 1 is a flowchart of a method for detecting a short circuit in a power cell based on an IC curve.
Fig. 2 is a schematic diagram of an IC curve of each cell in the present embodiment.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. 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 be within the scope of the invention.
As shown in fig. 1, a method for detecting a short circuit in a power battery based on an IC curve includes the following steps:
s1, acquiring charging data of a vehicle on line, wherein the charging data comprise voltage values of all battery cells.
S2, splitting a charging process according to charging data of the vehicle, and if the time interval of the front and rear pieces of charging data is greater than 10min, determining that the front and rear pieces of charging data respectively belong to two different charging processes.
And S3, cleaning charging data in a charging process, wherein in the charging process, if the same voltage value appears in the battery core repeatedly for 2 times or more than 2 times, only the charging data when the voltage value appears last time is reserved.
In theory, the voltage value of the battery core should be monotonically increased in a charging process, namely, the voltage value of the same battery core at the later time should be larger than the voltage value at the former time, but actually, the data returned by the voltage sensor of the vehicle shows that the voltage value of the battery core is unchanged, decreases or oscillates back and forth at certain time in a charging process.
S4, calculating dq/dvi of each battery cell i in a charging process; wherein i=1, 2,3,; dvi the voltage change of the cell i between the front and rear data during charging; dq represents the charge quantity of the battery between the front and rear data in the charging process, namely the integral of the charging current to the charging time; where dq/dvi refers to the charge of the battery when the cell voltage varies by one unit.
S5, respectively drawing an IC curve according to dq/dvi of each cell i, and calculating the envelope area Si of the IC curve of each cell i, wherein the abscissa represents the voltage value of the cell i, and the ordinate represents the dq/dvi of the cell i as shown in FIG. 2.
S6, the charge start voltage Vsi, the charge end voltage Vei, and the IC curve maximum value Mi, mi=max (dq/dvi) of each cell i are obtained.
S7, judging whether each cell i is an outlier: the battery cell i is characterized by each Si, vsi, vei, mi, si, vsi, vei, mi of the battery cell i is subjected to normalization processing, euclidean distance between the battery cell i and other battery cells is calculated by using Si, vsi, vei, mi after the normalization processing, distance and Di between the battery cell i and all other battery cells are calculated by using Euclidean distance between the battery cell i and other battery cells, whether the battery cell i is an outlier is judged by the distance and Di of the battery cell i, and if yes, the battery cell i possibly has an internal short circuit problem; the specific process is as follows:
s71, calculating the Euclidean distance dij between the cell i and other cells, namely the cell j, as follows:
wherein j=1, 2,..n and j+.i, sj is the IC curve envelope area of cell j, vsj is the charge start voltage of cell j, vej is the charge end voltage of cell j, mj is the maximum value of dq/dvj of cell j;
s72, calculating the distance sum Di between the battery cell i and all other battery cells as follows:
Di＝∑ j dij
s73, according to the distances and Di of all the battery cells i, the calculated average value Avg and standard deviation Std are as follows:
and S74, if the distance sum Di of the electric core i is Avg-alpha Std less than or equal to Di less than or equal to avg+alpha Std, the electric core i is not an outlier, otherwise, the electric core i is an outlier, namely the electric core i has the problem of internal short circuit. In this embodiment, α=3.
The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.
Claims (5)
1. The method for detecting the short circuit in the power battery based on the IC curve is characterized by comprising the following steps of:
s4, calculating dq/dvi of each battery cell i in a charging process; wherein i=1, 2,3,; dvi the voltage change of the cell i between the front and rear data during charging; dq represents the charge quantity of the battery between the front and rear data in the charging process;
s5, drawing an IC curve according to dq/dvi of each cell i, and respectively calculating the envelope area Si of the IC curve of each cell i; wherein the abscissa represents the voltage value of the cell i, and the ordinate represents dq/dvi of the cell i;
s6, acquiring a charging start voltage Vsi, a charging end voltage Vei and an IC curve maximum value Mi of each battery cell i; where mi=max (dq/dvi);
s7, judging whether each cell i is an outlier: calculating Euclidean distances between the battery cell i and other battery cells by using the IC curve envelope area Si of the battery cell i, the maximum value Mi of the IC curve, the charging starting voltage Vsi and the charging ending voltage Vei; calculating the distance and Di between the battery cell i and all other battery cells by using Euclidean distance between the battery cell i and other battery cells; and judging whether the battery cell i is an outlier or not according to the distance and Di of the battery cell i, and if so, indicating that the internal short circuit problem occurs.
2. The method for detecting a short circuit in a power battery based on an IC curve according to claim 1, wherein the specific procedure of step S7 is as follows:
s71, calculating the Euclidean distance dij between the cell i and other cells, namely the cell j, as follows:
wherein j=1, 2,..n and j+.i, sj is the IC curve envelope area of cell j, vsj is the charge start voltage of cell j, vej is the charge end voltage of cell j, mj is the maximum value of dq/dvj of cell j;
s72, calculating the distance sum Di between the battery cell i and all other battery cells as follows:
Di＝∑ j dij
s73, according to the distances and Di of all the cells i, the calculated average Avg and standard deviation Std are respectively:
and S74, if the distance sum Di of the electric core i is Avg-alpha Std less than or equal to Di less than or equal to avg+alpha Std, the electric core i is not an outlier, otherwise, the electric core i is an outlier, namely the electric core i has the problem of internal short circuit.
3. The method for detecting a short circuit in a power battery based on an IC curve according to claim 1 or 2, wherein in step S7, normalization processing is performed on the IC curve envelope area Si, the IC curve maximum value Mi, the charge start voltage Vsi, and the charge end voltage Vei of the battery i, and the euclidean distance is calculated by using the IC curve envelope area Si, the IC curve maximum value Mi, the charge start voltage Vsi, and the charge end voltage Vei of the battery i after normalization processing.
4. The method for detecting a short circuit in a power battery based on an IC curve according to claim 1, further comprising the steps of:
s1, acquiring charging data of a vehicle on line, wherein the charging data comprise voltage values of all battery cores;
s2, splitting a charging process according to charging data of the vehicle, and if the time interval of the front and rear pieces of charging data is larger than a set value, determining that the front and rear pieces of charging data respectively belong to two different charging processes.
5. The method for detecting a short circuit in a power cell based on an IC curve as defined in claim 4, further comprising:
and S3, cleaning charging data in a charging process, wherein in the charging process, if the same voltage value appears in the battery core repeatedly for 2 times or more than 2 times, only the charging data when the voltage value appears last time is reserved.
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| CN202311470094.4A CN117572268A (en) | 2023-11-07 | 2023-11-07 | Method for detecting short circuit in power battery based on IC curve |
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| CN202311470094.4A CN117572268A (en) | 2023-11-07 | 2023-11-07 | Method for detecting short circuit in power battery based on IC curve |
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