CN116540109A - Method for detecting internal short circuit of single lithium ion battery - Google Patents
Method for detecting internal short circuit of single lithium ion battery Download PDFInfo
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- CN116540109A CN116540109A CN202310543621.3A CN202310543621A CN116540109A CN 116540109 A CN116540109 A CN 116540109A CN 202310543621 A CN202310543621 A CN 202310543621A CN 116540109 A CN116540109 A CN 116540109A
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 145
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 145
- 238000000034 method Methods 0.000 title claims abstract description 42
- 239000013598 vector Substances 0.000 claims abstract description 55
- 238000007600 charging Methods 0.000 claims abstract description 33
- 230000008569 process Effects 0.000 claims abstract description 22
- 238000007599 discharging Methods 0.000 claims abstract description 17
- 230000008859 change Effects 0.000 claims description 20
- 230000001678 irradiating effect Effects 0.000 claims description 3
- 238000001514 detection method Methods 0.000 abstract description 8
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 5
- 229910052744 lithium Inorganic materials 0.000 abstract description 5
- 238000012986 modification Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000010287 polarization Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 238000009825 accumulation Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 210000004027 cell Anatomy 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000010280 constant potential charging Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
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- 230000005012 migration Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000000284 resting effect Effects 0.000 description 1
- 238000010998 test method Methods 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]
- G01R31/378—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
- 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The invention provides a detection method for internal short circuit of a single lithium ion battery, which relates to the field of lithium battery detection and comprises the steps of using n of the lithium ion battery 0 The relation between the current and time of the lithium ion battery in the first charging process in the secondary charging and discharging cycle is used as a standard vector, and the relation between the current and time of the lithium ion battery in the charging process in each charging and discharging cycle is used as a comparison vector; the invention discloses a detection method of internal short circuit of a single lithium ion battery, which can diagnose the internal short circuit of the single battery, does not need to apply other load resistors, can accurately judge whether the internal short circuit exists in the battery, and simultaneously avoids the batteryMisjudgment caused by the difference.
Description
Technical Field
The invention relates to the field of lithium battery detection, in particular to a detection method for an internal short circuit of a single lithium ion battery.
Background
With the rapid development of 3C-type portable electronic consumer products, power automobiles and terminal energy storage devices, the demand for lithium ion batteries is increasing. The lithium ion battery has the advantages of high energy, long service life, recoverability and the like, but certain potential safety hazards exist in the use process of the lithium ion battery, such as thermal failure caused by short circuit in the battery, hazardous gas generated by expanding gas of the battery, and analysis risk of the battery. The monitoring of the safety performance or failure index of the batteries is an important guarantee for realizing the safe operation of the lithium ion batteries.
The internal short circuit of the battery is always the focus of the safety problem of the lithium battery, once the internal short circuit of the battery occurs, loop current can be formed at a short circuit point, a large amount of heat is generated, and thermal runaway can be formed due to untimely heat dissipation in severe cases, so that safety accidents are caused. However, the internal short circuit generated by the battery in the normal cycle process is a process which gradually becomes serious from no to no, and is followed by a gradual cycle, so that the identification of the internal short circuit at the initial stage of the internal short circuit is an effective method for avoiding the battery safety accident.
The existing method for detecting the internal short circuit of the single lithium ion battery mainly comprises the following steps: 1. comparing the difference value of the voltages before and after the resting of the battery with a threshold value, diagnosing the internal short circuit of the power core, wherein the method generally needs to rest the battery for more than 24 hours and the threshold value is not uniform; 2. when the internal short circuit occurs, the battery generates self-discharge, so that in the actual charging process, the actual SOC and the charging capacity of the battery are low, the equivalent OCV can be calculated, and the actual SOC of the current battery is determined through the relation between the OCV and the SOC, so that whether the internal short circuit occurs in the battery is diagnosed, but the accuracy requirement of a model required by the method is higher, and the robustness is lower; 3. when the internal short circuit occurs, the battery may be fused, and the voltage will drop sharply and then rebound, which is less and has no conventional reference; 4. the internal short circuit of the battery is diagnosed by identifying the change of the battery parameters through the external load of the battery, such as the parallel connection of a constant voltage source to observe the change of current or the external connection of a resistor to observe the change of ohmic resistance of the battery, and the condition has higher requirements on the precision of the external load and is not in accordance with practical application.
Disclosure of Invention
The invention aims to provide a method for detecting internal short circuit of a single lithium ion battery, which can accurately detect the internal short circuit of the lithium ion battery.
In order to achieve the above object, the present invention provides the following technical solutions: a detection method of short circuit in a single lithium ion battery comprises the following steps: s1: obtaining the calibrated voltage drop K of the lithium ion battery 0 Confirming the voltage drop K of the current battery of the lithium ion battery 1 The method comprises the steps of carrying out a first treatment on the surface of the S2: when K is 1 <K 0 When the lithium ion battery, the switch and the photoresistor are connected in series; s3: opening the switch and conducting n-type operation on the lithium ion battery 0 After a number of charge and discharge cycles, the current voltage drop K of the lithium ion battery is measured 2 And at a frequency f 1 Recording the lithium ion battery at n 0 The voltage, current and capacity of the lithium ion battery during the secondary charge and discharge cycles; s4: closing the switch and n-conducting the lithium ion battery 1 And (3) charging and discharging cycles are carried out, and the intensity of a light source irradiating the photoresistor is changed so as to change the resistance value of the photoresistor, so that the resistance value of the photoresistor decays in a negative exponential manner along with the charge and discharge cycle times of the lithium ion battery and in a frequency f 1 Recording the lithium ion battery at n 1 The voltage, current and capacity of the lithium ion battery during the secondary charge and discharge cycles; s5: n is carried out on the lithium ion battery 1 Re-measurement after repeated charge and discharge cyclesObtaining the current voltage drop K of the lithium ion battery 3 The method comprises the steps of carrying out a first treatment on the surface of the S6: when max (K 1 ，K 2 )<K 0 <K 3 When the lithium ion battery is charged, confirming the relation between the current and time of the lithium ion battery in each charging process of the lithium ion battery; s7: n of the lithium ion battery 0 The relation between the current and time of the lithium ion battery in the first charging process in secondary charging and discharging cycles is used as a standard vector, the relation between the current and time of the lithium ion battery in the charging process in each charging and discharging cycle is used as a comparison vector, the magnitude of the current is used as the y-axis of the standard vector and the comparison vector, and the time is used as the x-axis of the standard vector and the comparison vector; s8: scaling the x-axis of each of the contrast vectors to align the contrast vector with the standard vector on the x-axis; s9: calculating the difference value between each comparison vector and the standard vector on the y axis along the x axis direction at the same interval, accumulating all the difference values between each comparison vector and the standard vector to obtain an accumulated minimum distance, and judging whether the lithium ion battery has internal short circuit or not by analyzing the change condition of the accumulated minimum distance along with the times of charge and discharge cycles of the lithium ion battery; s10: when judging that the lithium ion battery has an internal short circuit, acquiring an accumulated minimum distance when the lithium ion battery has the internal short circuit, and taking the accumulated minimum distance at the moment as a threshold value; s11: judging whether the accumulated minimum distance of the lithium ion battery to be detected exceeds a threshold value, and judging that the lithium ion battery to be detected has internal short circuit when the accumulated minimum distance of the lithium ion battery to be detected exceeds the threshold value.
Further, the frequency f 1 30 ms/time.
Further, the determining whether the lithium ion battery has an internal short circuit includes: setting a preset change value; judging whether the difference value of the accumulated minimum distances of every two adjacent charge and discharge cycles is larger than a preset change value, and judging that the lithium ion battery is internally short-circuited when the difference value is larger than the preset change value.
Further, in step S3, the lithium ion battery is charged and discharged at a constant current and a constant voltage at a rate of 1C, and the number of charging and discharging cycles of the lithium ion battery is n 0 =5; the charge cut-off current of the lithium ion battery is 0.05 ℃; in the charge and discharge cycle of the lithium ion battery, the interval between the charge and discharge of the lithium ion battery was 5min.
Further, in step S4, the lithium ion battery is charged and discharged at a constant current and a constant voltage at a rate of 1C, and the number of charging and discharging cycles of the lithium ion battery is n 1 =5; the charge cut-off current of the lithium ion battery is 0.05 ℃; in the charge and discharge cycle of the lithium ion battery, the interval between the charge and discharge of the lithium ion battery was 5min.
Further, the resistance value of the photoresistor is 10 omega-2000 omega.
Further, the same interval as described in step S9 is 30ms.
Further, the light source is a variable light intensity power supply.
According to analysis, the invention discloses a detection method for the internal short circuit of the single lithium ion battery, which can diagnose the internal short circuit of the single battery, does not need to apply other load resistors, can accurately judge whether the short circuit exists in the battery, and simultaneously avoids misjudgment caused by the difference of the batteries.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. Wherein:
fig. 1 is an equivalent circuit diagram of an internal short-circuit battery according to an embodiment of the present invention.
Figure 2 is a flow chart of the present invention.
Detailed Description
The invention will be described in detail below with reference to the drawings in connection with embodiments. The examples are provided by way of explanation of the invention and not limitation of the invention. Indeed, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For example, features illustrated or described as part of one embodiment can be used on another embodiment to yield still a further embodiment. Accordingly, it is intended that the present invention encompass such modifications and variations as fall within the scope of the appended claims and their equivalents.
In the description of the present invention, the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", etc. refer to the orientation or positional relationship based on that shown in the drawings, merely for convenience of description of the present invention and do not require that the present invention must be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. The terms "coupled," "connected," and "configured" as used herein are to be construed broadly and may be, for example, fixedly connected or detachably connected; can be directly connected or indirectly connected through an intermediate component; either a wired electrical connection, a radio connection or a wireless communication signal connection, the specific meaning of which terms will be understood by those of ordinary skill in the art as the case may be.
One or more examples of the invention are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms "first," "second," "third," and "fourth," etc. are used interchangeably to distinguish one component from another and are not intended to represent the location or importance of the individual components.
As shown in fig. 2, according to an embodiment of the present invention, there is provided a method for detecting an internal short circuit of a single lithium ion battery, including the steps of:
s1: obtaining the calibrated voltage drop K of the lithium ion battery 0 Confirming the voltage drop K of the current battery of the lithium ion battery 1 This example employs LCO/graphite system batteriesThe voltage was 3.0V-4.45V, and the K value of the fresh battery was first tested (using a 48h test method, k= (v1=v2)/t) was denoted as K 1 If K 1 <K 0 (K 0 Calibration for battery manufacturers) then the battery is considered to have no internal short circuit, and then the components such as the battery, the bright-cut, the photoresistor (10-2000 omega) and the like are assembled and connected according to the diagram shown in fig. 1;
s2: when K is 1 <K 0 When the lithium ion battery, the switch and the photoresistor are connected in series, the photoresistor and the switch are equivalent to external resistors, and no internal short circuit occurs when the battery is in the battery in the circulation process due to the fact that the battery is in the battery in the early production process. The internal short circuit of the battery mainly occurs in the middle and later stages of the battery cycle, and the main reasons for the internal short circuit are two points; 1. the gas is generated due to the decomposition of the electrolyte, so that the structure of the battery is damaged, and the conditions of diaphragm dislocation, pole piece movement and the like cause internal short circuit; 2. the cell tends to be associated with lithium evolution at a later stage of the cycle, and the generation of lithium dendrites has the risk of penetrating the membrane. But normally the creation of internal shorts is relatively slow and often requires time to deposit. Meanwhile, in the latter cycle, the capacity accumulation stage occurs in the constant voltage charging stage due to the increase of polarization, and in this stage, the current gradually decreases, and the internal short circuit should be gradually increased along with the time migration, so that the short circuit current gradually increases, and the current drop caused by the internal short circuit becomes obvious. In summary, the present invention adopts the external resistor method to simulate the internal short circuit of the battery, unlike the conventional external internal short circuit method, the present invention adopts an external photosensitive variable resistor, and changes the resistance value of the external resistor by adjusting the light intensity, so as to simulate the gradual accumulation of the variation of the internal short circuit of the battery in the cycle process, and fig. 1 is an equivalent circuit diagram of the battery after connecting the switch and the photosensitive resistor, wherein: u (U) OCV Is open circuit voltage, R 0 Is ohmic resistance, R c And C is polarization resistance and polarization capacitance, respectively, U 0 The voltage is terminal voltage, LDR is photoresistor, and LED is variable light intensity power supply.
S3: switch off and n is carried out on lithium ion battery 0 After the charge and discharge cycles, the current voltage drop K of the lithium ion battery is measured 2 And at a frequency f 1 Recording the lithium ion battery at n 0 The voltage, current and capacity of the lithium ion battery are charged by adopting a multiplying factor constant current and constant voltage of 1C under the condition of not externally connecting a resistor in the process of secondary charging and discharging circulation until the current is 0.05C, the charging is carried out for 5min, the charging is carried out by adopting 1C for constant current discharging, the charging is carried out for 5min, the charging is circulated for 5 weeks, and the K value of the battery is recorded as K according to the test in the step 1 2 Comparative K 2 And K is equal to 0 、K 1 It was determined that the cell was not significantly different from the initial after 5 weeks of cycling.
S4: closing the switch and carrying out n on the lithium ion battery 1 The charge and discharge cycles are carried out for a plurality of times, and the intensity of a light source irradiating the photoresistor is changed at the same time, so that the resistance value of the photoresistor is changed, and the resistance value of the photoresistor decays in a negative exponential manner along with the charge and discharge cycle times of the lithium ion battery and is in a frequency f 1 Recording the lithium ion battery at n 1 The voltage of the lithium ion battery, the current of the lithium ion battery and the capacity of the lithium ion battery in the process of secondary charging and discharging cycles, after a switch is turned on, the resistance value of a photoresistor is enabled to be negative exponentially attenuated along with the cycle times from large to small under the irradiation of a light source, the cycle is continued for 5 weeks according to the previous multiplying power, and meanwhile, the K value is tested again after 5 weeks of the cycle (the test K value is considered to be a virtual battery for testing the battery and the external resistor at the moment), and the K value is recorded as K 3 Comparative K 3 And K is equal to 0 、K 1 And K 2 Determining the size of max (K 1 ，K 2 )<K 0 <K 3 Recording data such as voltage, current, capacity and the like in the circulation process, and taking the data as a data source, wherein the acquisition frequency is 30 ms/time;
s5: n in lithium ion battery 1 Measuring the current voltage drop K of the lithium ion battery again after the secondary charge and discharge cycles 3 ；
S6: when max (K 1 ，K 2 )<K 0 <K 3 When the lithium ion battery is charged, confirming the relation between the current and time of the lithium ion battery in each charging process of the lithium ion battery;
s7: n of lithium ion battery 0 The relation between the current and time of the lithium ion battery in the first charging process in the secondary charging and discharging cycles is used as a standard vector, the relation between the current and time of the lithium ion battery in the charging process in each charging and discharging cycle is used as a comparison vector, wherein the magnitude of the current is used as the y-axis of the standard vector and the comparison vector, and the time is used as the x-axis of the standard vector and the comparison vector;
s8: scaling the x-axis of each contrast vector to align the contrast vector with the standard vector on the x-axis, mainly utilizing the I-t curve of the constant voltage stage (curve of the standard vector and the contrast vector in the x-axis and y-axis coordinate systems) in the data analysis stage, matching the dynamic time adjustment (Dynamic Time Warping, DTW) of the contrast vector with the time sequence of the standard vector to keep consistency with the time sequence of the standard vector, and obtaining the current difference value of the standard vector and the standard vector at the same time;
s9: calculating the difference value between each contrast vector and the standard vector on the y axis along the x axis direction at the same interval, accumulating all the difference values between each contrast vector and the standard vector to obtain accumulated minimum distance, after the circulation is finished, deriving data, firstly extracting current and time data in the constant voltage charging process, adopting particle filtering to carry out noise reduction treatment on an I-t curve (curve of the standard vector and the contrast vector in the x axis and the y axis coordinate system), then taking the I-t data of the first circle as the standard vector, utilizing matlab to align the latter circulation data with the first circle standard vector through dynamic time adjustment, obtaining accumulated minimum distance with the standard vector, judging whether internal short circuit occurs in the lithium ion battery by analyzing the change condition of the accumulated minimum distance along with the times of charging and discharging cycles of the lithium ion battery, taking the sum of the current difference values (accumulated minimum distance) as a parameter value of judging battery internal short circuit judging standard, determining a threshold value by analyzing the change condition of the accumulated minimum distance along with the circulation times, and judging whether internal short circuit occurs or not;
s10: when judging that the lithium ion battery has an internal short circuit, acquiring the accumulated minimum distance when the lithium ion battery has the internal short circuit, and taking the accumulated minimum distance at the moment as a threshold value;
s11: judging whether the accumulated minimum distance of the lithium ion battery to be detected exceeds a threshold value, judging that the lithium ion battery to be detected is in internal short circuit when the accumulated minimum distance of the lithium ion battery to be detected exceeds the threshold value, and judging whether the lithium ion battery to be tested is in internal short circuit according to the threshold value after the threshold value of the lithium ion battery is determined.
Preferably, the frequency f 1 At 30 ms/time, a sufficient number of values can be obtained at a frequency of 30 ms/time to establish a subsequent I-t curve.
Preferably, determining whether an internal short circuit of the lithium ion battery occurs includes: setting a preset change value; judging whether the difference value of the accumulated minimum distances of every two adjacent charge and discharge cycles is larger than a preset change value, judging that the lithium ion battery is internally short-circuited when the difference value is larger than the preset change value, judging whether the lithium ion battery is internally short-circuited by observing the change amplitude of the accumulated minimum distances, and proving that the battery is internally short-circuited when the change amplitude is overlarge. Preferably, in step S3, the lithium ion battery is charged and discharged at a constant current and a constant voltage at a rate of 1C, and the number of charge and discharge cycles of the lithium ion battery is n 0 =5; the charge cut-off current of the lithium ion battery is 0.05 ℃; in the charge and discharge cycle of the lithium ion battery, the interval between the charge and discharge of the lithium ion battery is 5min, the charge and discharge rate of 1C can be increased as much as possible under the condition of ensuring the normal operation of the battery, the interval between the charge and discharge is 5min, the overheat of the battery caused by the charge and discharge can be reduced, and the cycle times n under the normal condition can be reduced 0 Sufficient data samples were taken for 5 weeks.
Preferably, in step S4, the lithium ion battery is charged and discharged at a constant current and a constant voltage at a rate of 1C, and the number of charge and discharge cycles of the lithium ion battery is n 1 ＝5；
The charge cut-off current of the lithium ion battery is 0.05 ℃;
in the charge and discharge cycle of the lithium ion battery, the interval between the charge and discharge of the lithium ion battery was 5min.
Preferably, the resistance of the photoresistor is 10 omega-2000 omega, and the 10 omega-2000 omega can simulate most loads, and the resistance of the photoresistor is simple to regulate and control and easy to operate.
Preferably, the same interval in step S9 is 30ms, and the interval in S9 is equal to the frequency f 1 The same, thereby enabling the standard vector to be compared with the scaled contrast vector based on the actual point values it acquired.
Preferably, the light source is a variable light intensity power supply, and a variable light intensity LED light emitting device is generally selected.
Compared with the prior art, the invention discloses a detection method for the internal short circuit of a single lithium ion battery, which can diagnose the internal short circuit of the single battery without applying other load resistors, and in the circulation process, the I-t time curve of the battery is continuously updated, the accumulated minimum distance between the I-t time curve and a standard time sequence is also continuously updated, when a certain value is reached, the internal short circuit of the battery is obviously increased, and meanwhile, the misjudgment caused by the difference of the batteries is avoided, namely, the threshold value of each single battery is defined by the self previous characteristic.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. The method for detecting the internal short circuit of the single lithium ion battery is characterized by comprising the following steps of:
s1: obtaining the calibrated voltage drop K of the lithium ion battery 0 Confirming the voltage drop K of the current battery of the lithium ion battery 1 ；
S2: when K is 1 <K 0 When the lithium ion battery, the switch and the photoresistor are connected in series;
s3: opening the switch and aiming at the lithium ion batteryProceeding n 0 After a number of charge and discharge cycles, the current voltage drop K of the lithium ion battery is measured 2 And at a frequency f 1 Recording the lithium ion battery at n 0 The voltage, current and capacity of the lithium ion battery during the secondary charge and discharge cycles;
s4: closing the switch and n-conducting the lithium ion battery 1 And (3) charging and discharging cycles are carried out, and the intensity of a light source irradiating the photoresistor is changed so as to change the resistance value of the photoresistor, so that the resistance value of the photoresistor decays in a negative exponential manner along with the charge and discharge cycle times of the lithium ion battery and in a frequency f 1 Recording the lithium ion battery at n 1 The voltage, current and capacity of the lithium ion battery during the secondary charge and discharge cycles;
s5: n is carried out on the lithium ion battery 1 Measuring the current voltage drop K of the lithium ion battery again after the charge and discharge cycles 3 ；
S6: when max (K 1 ，K 2 )<K 0 <K 3 When the lithium ion battery is charged, confirming the relation between the current and time of the lithium ion battery in each charging process of the lithium ion battery;
s7: n of the lithium ion battery 0 The relation between the current and time of the lithium ion battery in the first charging process in secondary charging and discharging cycles is used as a standard vector, the relation between the current and time of the lithium ion battery in the charging process in each charging and discharging cycle is used as a comparison vector, the magnitude of the current is used as the y-axis of the standard vector and the comparison vector, and the time is used as the x-axis of the standard vector and the comparison vector;
s8: scaling the x-axis of each of the contrast vectors to align the contrast vector with the standard vector on the x-axis;
s9: calculating the difference value between each comparison vector and the standard vector on the y axis along the x axis direction at the same interval, accumulating all the difference values between each comparison vector and the standard vector to obtain an accumulated minimum distance, and judging whether the lithium ion battery has internal short circuit or not by analyzing the change condition of the accumulated minimum distance along with the times of charge and discharge cycles of the lithium ion battery;
s10: when judging that the lithium ion battery has an internal short circuit, acquiring an accumulated minimum distance when the lithium ion battery has the internal short circuit, and taking the accumulated minimum distance at the moment as a threshold value;
s11: judging whether the accumulated minimum distance of the lithium ion battery to be detected exceeds a threshold value, and judging that the lithium ion battery to be detected has internal short circuit when the accumulated minimum distance of the lithium ion battery to be detected exceeds the threshold value.
2. The method for detecting an internal short circuit of a single lithium ion battery according to claim 1, wherein the frequency f 1 30 ms/time.
3. The method for detecting an internal short circuit in a single lithium ion battery according to claim 1, wherein the determining whether the internal short circuit occurs in the lithium ion battery comprises:
setting a preset change value;
judging whether the difference value of the accumulated minimum distances of every two adjacent charge and discharge cycles is larger than a preset change value, and judging that the lithium ion battery is internally short-circuited when the difference value is larger than the preset change value.
4. The method for detecting an internal short circuit of a single lithium ion battery according to claim 1, wherein in step S3, the lithium ion battery is charged and discharged at a constant current and constant voltage at a rate of 1C, and the number of charging and discharging cycles of the lithium ion battery is n 0 ＝5；
The charge cut-off current of the lithium ion battery is 0.05 ℃;
in the charge and discharge cycle of the lithium ion battery, the interval between the charge and discharge of the lithium ion battery was 5min.
5. Root of Chinese characterThe method for detecting an internal short circuit of a single lithium ion battery according to claim 1, wherein in step S4, the lithium ion battery is charged and discharged at a constant current and constant voltage at a rate of 1C, and the number of charge and discharge cycles of the lithium ion battery is n 1 ＝5；
The charge cut-off current of the lithium ion battery is 0.05 ℃;
in the charge and discharge cycle of the lithium ion battery, the interval between the charge and discharge of the lithium ion battery was 5min.
6. The method for detecting an internal short circuit of a single lithium ion battery according to claim 1, wherein the resistance value of the photoresistor is 10Ω -2000 Ω.
7. The method according to claim 1, wherein the same interval in step S9 is 30ms.
8. The method for detecting an internal short circuit of a single lithium ion battery according to claim 1, wherein the light source is a variable light intensity power supply.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2022110281398 | 2022-08-25 | ||
| CN202211028139.8A CN115327396A (en) | 2022-08-25 | 2022-08-25 | Method for detecting short circuit in single lithium ion battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116540109A true CN116540109A (en) | 2023-08-04 |
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