CN115980596B - Method for detecting internal short circuit of power battery on line - Google Patents
Method for detecting internal short circuit of power battery on line Download PDFInfo
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- CN115980596B CN115980596B CN202310256842.2A CN202310256842A CN115980596B CN 115980596 B CN115980596 B CN 115980596B CN 202310256842 A CN202310256842 A CN 202310256842A CN 115980596 B CN115980596 B CN 115980596B
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Abstract
The invention discloses a method for detecting an internal short circuit of a power battery on line, which relates to the technical field of power batteries and comprises the following steps: acquiring charging data of a vehicle battery on line, wherein the charging data comprise voltage values of all battery cores; splitting a charging process of the vehicle battery according to charging data of the vehicle battery, and splitting the charging data of the vehicle battery into charging data of a plurality of charging processes; screening a plurality of charging processes obtained after splitting respectively to screen out charging processes in which all the battery cells are completely charged; calculating the internal short circuit degree value of each battery cell according to the screened charging data of the charging process; and respectively judging the internal short circuit state of each cell according to the internal short circuit degree value of each cell. The invention can utilize common data and detect the internal short circuit state of the power battery on line in real time, and is easy to realize and popularize.
Description
Technical Field
The invention relates to the technical field of power batteries, in particular to a method for detecting an internal short circuit of a power battery on line.
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.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a method for detecting the internal short circuit of the power battery on line, which can utilize common data and detect the internal short circuit state of the power battery on line in real time.
In order to achieve the above purpose, the present invention adopts the following technical scheme, including:
a method for on-line detection of a short circuit in a power cell, comprising the steps of:
s1, acquiring charging data of a battery on line, wherein the charging data comprise voltage values of all battery cells;
s2, splitting the charging process of the battery according to the charging data of the battery, and splitting the charging data of the battery into charging data of a plurality of charging processes;
s3, screening the plurality of charging processes obtained after the splitting in the step S2 respectively, and screening out the charging processes that all the battery cells are completely charged;
s4, calculating the internal short circuit degree value of each battery cell according to the charging data of the charging process screened in the step S3;
s5, respectively judging the internal short circuit state of each cell according to the internal short circuit degree value of each cell.
Preferably, in step S2, the splitting manner is as follows: if the time interval between two adjacent pieces of data is greater than the set threshold value Tth in the charging data of the battery, the two adjacent pieces of data are considered to belong to two different charging processes respectively, namely, the charging data of the two different charging processes respectively.
Preferably, the threshold value tth=10min is set.
Preferably, in step S3, the screening process is as follows:
s31, in a charging process, recording the minimum time when the voltage value of the battery cell i reaches the first near-cut-off voltage as Ai time and the minimum time when the voltage value of the battery cell i reaches the second near-cut-off voltage as Bi time aiming at the battery cell i;
wherein the first near-cutoff voltage < the second near-cutoff voltage < the cutoff voltage;
i represents the number of cells in the battery, there are M cells in the battery, i=1, 2, ·m;
s32, in a charging process, if the battery cell i has the Ai moment and the Bi moment at the same time, the battery cell i is completely charged in the charging process; otherwise, the battery cell i is incompletely charged in the charging process;
s33, screening out the charging process that all the battery cells are completely charged.
Preferably, in step S31,
the first near-cutoff voltage, dV1= (Vo- Δv1) ± 3;
the second near-cutoff voltage, dV2= (Vo- Δv2) ± 3;
wherein dV1 is a first near cut-off voltage, vo is a cut-off voltage, and DeltaV 1 is a set first differential pressure; dV2 is the second near-cutoff voltage, and Deltav 2 is the set second differential pressure; Δv2< Δv1.
Preferably, the first differential pressure Δv1=350 mV is set, and the second differential pressure Δv2=250 mV is set.
Preferably, in step S33, if all the battery cells in the plurality of charging processes are fully charged, a charging process in which all the battery cells closest to the current time are fully charged is selected.
Preferably, in step S4, the specific calculation mode is as follows:
s41, respectively calculating the time difference delta ti between the Ai moment and the Bi moment of each cell i according to the charging data of the charging process screened in the step S3, wherein delta ti=Bi-Ai;
s42, selecting the minimum value, namely min (delta ti), from the time differences delta ti of all the battery cells i, and taking the minimum value min (delta ti) as a standard deviation;
s43, respectively calculating the internal short circuit degree value sci=delta ti/min (delta ti) of each cell i;
wherein Deltati is the time difference between the Ai time and the Bi time of the battery cell i; SCi is the internal short circuit degree value of the cell i.
Preferably, in step S5, if the internal short circuit degree value of a certain cell is greater than the set threshold SCth, determining that the cell is in an internal short circuit state; otherwise, the battery cell is not judged to be in an internal short circuit state.
Preferably, the set threshold scth=1.5.
The invention has the advantages that:
(1) Compared with the existing detection method, the method has the main advantages that: 1. the method is easy to realize, and real-time online detection can be realized without adding an additional sensor. 2. The method is easy to fall to the ground, and can be used in the normal vehicle running process because the method is only used for the problem of a laboratory in the existing part detection method and has low requirements on data acquisition precision and acquisition frequency.
(2) The invention directly uses the online data to calculate the internal short circuit degree of the battery cell, has low realization cost and is easy to popularize.
(3) The invention quantifies the internal short circuit degree of the battery cells, so that the internal short circuit degree among different cells is easy to compare.
(4) The comparison of internal short circuits is actually to compare the self-discharge effect of the battery, and in fact, all the battery cells have internal short circuits to a certain extent, and only when the internal short circuits are large enough, attention should be paid, so that the battery cells cannot be problematic at the same time. Therefore, when the internal short circuit degree value is calculated in the step S4, the time difference and the minimum time difference of each cell are obtained, then the time difference and the minimum time difference are compared by utilizing the ratio, the cell with the minimum time difference is actually considered to be a normal cell, the cell with higher internal short circuit degree can be directly found by comparing the time difference of different cells, and when the time difference is higher than a certain threshold value, the cell is considered to be abnormal.
Drawings
Fig. 1 is a flowchart of a method for detecting an internal short circuit of a power battery on line.
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 an internal short circuit of a power battery on line includes the following steps:
s1, acquiring charging data of a vehicle battery on line, wherein the charging data comprise voltage values of all battery cells.
Wherein, the number of the electric core in the battery is represented by i, and the battery has M electric cores, i=1, 2, & M.
S2, splitting the charging process of the vehicle battery according to the charging data of the vehicle battery, and splitting the charging data of the vehicle battery into charging data of a plurality of charging processes.
The splitting mode is as follows: if the time interval between two adjacent pieces of data is greater than the set threshold value Tth, the two adjacent pieces of data are considered to belong to two different charging processes, namely, the charging data of the two different charging processes. In the present embodiment, the threshold tth=10min.
S3, screening a plurality of charging processes obtained through the division in the step S2, wherein the screening processes are as follows:
s31, in a charging process, recording the minimum time when the voltage value of the battery cell i reaches the first near-cut-off voltage as Ai time and the minimum time when the voltage value of the battery cell i reaches the second near-cut-off voltage as Bi time aiming at the battery cell i;
the first near-cutoff voltage, dV1= (Vo- Δv1) ± 3;
the second near-cutoff voltage, dV2= (Vo- Δv2) ± 3;
wherein dV1 is a first near cut-off voltage, vo is a cut-off voltage, and DeltaV 1 is a set first differential pressure; dV2 is the second near-cutoff voltage, and Deltav 2 is the set second differential pressure; Δv2< Δv1, dV1< dV2< Vo. In this example, Δv2=250 mV, Δv1=350 mV.
Generally, a battery has multiple battery cells, and if a certain battery cell reaches a charge cutoff voltage during a battery charging process, the battery stops charging, and the electric quantity is displayed as full charge of the battery.
S32, in a charging process, if the battery cell i has the Ai moment and the Bi moment at the same time, the battery cell i is completely charged in the charging process; otherwise, the battery cell i is incompletely charged in the charging process;
s33, screening out a charging process that all the battery cells are completely charged; if all the battery cells in the plurality of charging processes are completely charged, selecting a charging process in which all the battery cells closest to the current moment are completely charged, namely selecting a charging process in which all the latest battery cells are completely charged.
S4, calculating the internal short circuit degree value of each battery cell according to the charging data of the charging process screened in the step S3, wherein the specific calculation mode is as follows:
s41, respectively calculating the time difference delta ti between the Ai time and the Bi time of each cell i according to the charging data of the charging process screened in the step S3, wherein delta ti=Bi-Ai.
Δti is the time difference between the Ai time and the Bi time of the cell i.
S42, selecting the minimum value, namely min (delta ti), from the time differences delta ti of all the battery cells i, and taking the minimum value min (delta ti) as the standard deviation.
S43, the internal short circuit degree value sci=Δti/min (Δti) of each cell i is calculated.
SCi is the internal short circuit degree value of the cell i.
S5, if the internal short-circuit degree value of a certain cell is larger than a set threshold SCth, judging that the cell is in an internal short-circuit state; otherwise, the battery cell is not judged to be in an internal short circuit state. Wherein, the larger the internal short-circuit degree value is, the more serious the internal short-circuit condition is. In this embodiment, the threshold scth=1.5.
The invention directly uses the online data to calculate the internal short circuit degree of the battery cell, has low realization cost and is easy to popularize.
The invention quantifies the internal short circuit degree of the battery cells, so that the internal short circuit degree among different cells is easy to compare. The comparison of internal short circuits is actually to compare the self-discharge effect of the battery, and in fact, all the battery cells have a certain degree of internal short circuits, and only when the degree of internal short circuits is large enough, attention should be paid, so that the battery cells cannot be problematic at the same time. Therefore, when the internal short circuit degree value of the battery core is calculated in the step S4, the time difference and the minimum time difference of each battery core are obtained, then the time difference and the minimum time difference are compared by utilizing the ratio, the battery core with the minimum time difference is actually considered to be a normal battery core, the battery core with higher internal short circuit degree can be directly found by comparing the time difference of different battery cores, and when the time difference is higher than a certain threshold value, the battery core is considered to be abnormal.
In this embodiment, the power battery of a certain vehicle includes 28 battery cells, taking the power battery as an example, according to the manner of step S2, the charging process of the power battery is split into a plurality of charging processes according to the charging data of the power battery, and the charging data of the power battery is split into the charging data of the plurality of charging processes.
In this embodiment, the charge cut-off voltage vo=3650 mV, Δv2=250 mV, Δv1=350 mV of the power battery, and the first near cut-off voltage dv1=3300±3 and the second near cut-off voltage dv2=3400±3 are obtained.
In a charging process, regarding the 1 st cell, the voltage value of the 1 st cell is denoted as Hv1, and according to the manner of step S31, the time A1, which is the minimum time when the voltage value Hv1 of the 1 st cell reaches the first near-cutoff voltage dV1, is obtained, and the time B1, which is the minimum time when the voltage value Hv1 of the 1 st cell reaches the second near-cutoff voltage dV2, is obtained. According to the method of step S31, the Ai time and the Bi time of each cell i are obtained for each cell i.
And screening out a charging process of complete charging according to the mode of the steps S32-S33.
According to the method of step S4, according to the Ai time and the Bi time of each cell i, the time difference Δti of each cell i is calculated, and the minimum value is selected from the time differences Δti of all the cells i, so as to calculate and obtain the internal short-circuit degree value SCi of each cell i, and the calculation result shows that the internal short-circuit degree value of each cell is about 1, so that all the cells of the power battery have no serious internal short-circuit condition.
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 (7)
1. A method for detecting an internal short circuit of a power cell on-line, comprising the steps of:
s1, acquiring charging data of a battery on line, wherein the charging data comprise voltage values of all battery cells;
s2, splitting the charging process of the battery according to the charging data of the battery, and splitting the charging data of the battery into charging data of a plurality of charging processes;
s3, screening the plurality of charging processes obtained after the splitting in the step S2 respectively, and screening out the charging processes that all the battery cells are completely charged;
s4, calculating the internal short circuit degree value of each battery cell according to the charging data of the charging process screened in the step S3;
s5, respectively judging the internal short circuit state of each cell according to the internal short circuit degree value of each cell;
in step S3, the screening process is as follows:
s31, in a charging process, recording the minimum time when the voltage value of the battery cell i reaches the first near-cut-off voltage as Ai time and the minimum time when the voltage value of the battery cell i reaches the second near-cut-off voltage as Bi time aiming at the battery cell i;
wherein the first near-cutoff voltage < the second near-cutoff voltage < the cutoff voltage;
i represents the number of cells in the battery, there are M cells in the battery, i=1, 2, ·m;
s32, in a charging process, if the battery cell i has the Ai moment and the Bi moment at the same time, the battery cell i is completely charged in the charging process; otherwise, the battery cell i is incompletely charged in the charging process;
s33, screening out a charging process that all the battery cells are completely charged;
in step S4, the specific calculation method is as follows:
s41, respectively calculating the time difference delta ti between the Ai moment and the Bi moment of each cell i according to the charging data of the charging process screened in the step S3, wherein delta ti=Bi-Ai;
s42, selecting the minimum value, namely min (delta ti), from the time differences delta ti of all the battery cells i, and taking the minimum value min (delta ti) as a standard deviation;
s43, respectively calculating the internal short circuit degree value sci=delta ti/min (delta ti) of each cell i;
wherein Deltati is the time difference between the Ai time and the Bi time of the battery cell i; SCi is the internal short circuit degree value of the battery cell i;
in step S5, if the internal short circuit degree value of a certain cell is greater than the set threshold SCth, determining that the cell is in an internal short circuit state; otherwise, the battery cell is not judged to be in an internal short circuit state.
2. The method for online detecting a short circuit in a power battery according to claim 1, wherein in step S2, the splitting manner is as follows: if the time interval between two adjacent pieces of data is greater than the set threshold value Tth in the charging data of the battery, the two adjacent pieces of data are considered to belong to two different charging processes respectively, namely, the charging data of the two different charging processes respectively.
3. A method of on-line detection of a short circuit in a power cell according to claim 2, characterized in that the threshold Tth = 10min is set.
4. The method for on-line detection of a short circuit in a power cell according to claim 1, wherein, in step S31,
the first near-cutoff voltage, dV1= (Vo- Δv1) ± 3;
the second near-cutoff voltage, dV2= (Vo- Δv2) ± 3;
wherein dV1 is a first near cut-off voltage, vo is a cut-off voltage, and DeltaV 1 is a set first differential pressure; dV2 is the second near-cutoff voltage, and Deltav 2 is the set second differential pressure; Δv2< Δv1.
5. The method of claim 4, wherein the first differential pressure Δv1=350 mV and the second differential pressure Δv2=250 mV are set.
6. The method according to claim 1, wherein in step S33, if all the cells in the plurality of charging processes are fully charged, a charging process in which all the cells closest to the current time are fully charged is selected.
7. The method for on-line detection of a short circuit in a power cell according to claim 1, wherein the set threshold SCth = 1.5.
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| CN106932722A (en) * | 2015-12-30 | 2017-07-07 | 华为技术有限公司 | The internal short-circuit detection method and device of a kind of electrokinetic cell |
| CN107064803B (en) * | 2016-12-16 | 2019-12-13 | 蔚来汽车有限公司 | on-line detection method for short circuit in battery |
| CN112666468B (en) * | 2019-09-30 | 2024-06-11 | Oppo广东移动通信有限公司 | Method and device for detecting short circuit in battery and electronic equipment |
| KR102283954B1 (en) * | 2019-11-05 | 2021-07-29 | 정대원 | Battery Short Circuit Detection System And Battery Short Circuit Detection Method Using Same |
| CN214850546U (en) * | 2021-03-17 | 2021-11-23 | 深圳市安仕新能源科技有限公司 | Battery management system |
| CN113884922B (en) * | 2021-10-28 | 2022-11-18 | 同济大学 | Battery internal short circuit quantitative diagnosis method based on voltage and electric quantity outlier coefficient |
| CN114137417B (en) * | 2021-11-19 | 2023-01-17 | 北京理工大学 | Battery internal short circuit detection method based on charging data characteristics |
| CN114252792A (en) * | 2021-12-23 | 2022-03-29 | 蜂巢能源科技(无锡)有限公司 | Method and device for detecting internal short circuit of battery pack, electronic equipment and storage medium |
| CN114705998A (en) * | 2022-04-28 | 2022-07-05 | 中国第一汽车股份有限公司 | Battery abnormality recognition method and device, storage medium and vehicle |
| CN115436825A (en) * | 2022-05-30 | 2022-12-06 | 北京车和家汽车科技有限公司 | Method, device and equipment for detecting abnormal state of single battery cell and storage medium |
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