CN114035074A - Method for diagnosing micro short-circuit monomer in lithium iron phosphate series battery pack - Google Patents
Method for diagnosing micro short-circuit monomer in lithium iron phosphate series battery pack Download PDFInfo
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- 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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- G01R31/3842—Arrangements for monitoring battery or accumulator variables, e.g. SoC combining voltage and current measurements
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- 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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Abstract
The invention discloses a method for diagnosing a micro short circuit monomer in a lithium iron phosphate series battery pack, which comprises the following steps of: step 1, charging a lithium iron phosphate battery pack twice, and respectively positioning two platform-period voltage values in a voltage curve of a charging end of a single battery according to working data of the lithium iron phosphate battery pack; step 2, respectively acquiring a first voltage reference line and a second voltage reference line of each single battery to be tested; step 3, recording the time of each single battery to be tested reaching the first voltage reference line and the second voltage reference line respectively, and recording as the first charging time and the second charging time of each single battery to be tested; step 4, calculating a first reference charging capacity and a second reference charging capacity; step 5, calculating the leakage current of each single battery to be tested; and 6, judging whether each single battery to be tested is a micro short circuit single body according to the micro short circuit resistance value of each single battery to be tested.
Description
Technical Field
The invention relates to the technical field of battery management systems, in particular to a method for diagnosing a micro short-circuit monomer in a lithium iron phosphate series battery pack.
Background
Lithium ion batteries have many advantages such as high energy and power density and long cycle life, and are therefore favored by various power storage devices. Meanwhile, the lithium iron phosphate battery with low cost and better safety is better than the ternary lithium battery in yield and loading capacity. However, in any of the batteries, there is a risk of a micro short circuit of the battery due to various causes such as dust, burrs of raw materials, and the like during the production process, or abuse during the use process. The battery generates a micro short circuit to cause the internal self-loop, continuously consumes the battery power, increases the inconsistency of the battery pack, not only can influence the overall performance of the battery pack, but also can lead the self-discharge rate of the battery to be gradually improved along with the rising of the micro short circuit degree, increases the heat production quantity, even generates serious safety problems such as thermal runaway and the like. Therefore, it is very important to find an effective method for diagnosing micro-shorted cells in a battery pack.
Most of the existing methods are directed at the ternary lithium battery, but the voltage curve of the lithium iron phosphate battery has two obvious platform periods more than that of the ternary lithium battery, so that the diagnosis method of the ternary lithium battery is not suitable for the lithium iron phosphate battery any more. In addition, in some methods, micro short circuit detection needs to be performed according to working conditions of full charge and full discharge, and for actual user use conditions, due to reasons of mileage anxiety, quick charge and the like, ideal charge and discharge use conditions are few, so that the applicability and accuracy of the method are reduced.
Disclosure of Invention
The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of diagnosing a micro short-circuit cell in a lithium iron phosphate series battery.
The invention provides a method for diagnosing a micro short-circuit monomer in a lithium iron phosphate series battery pack, which is characterized by comprising the following steps of: step 1, charging a lithium iron phosphate battery pack twice, and respectively positioning two platform-period voltage values in a voltage curve of a charging end of a single battery according to working data of the lithium iron phosphate battery pack; step 2, respectively acquiring a first voltage reference line and a second voltage reference line of each single battery to be tested according to the first plateau voltage value and the second plateau voltage value; step 3, recording the time of each single battery to be tested reaching the first voltage reference line and the second voltage reference line respectively, and recording as the first charging time and the second charging time of each single battery to be tested; step 4, calculating a first reference charging electric quantity and a second reference charging electric quantity according to the first charging time and the second charging time; step 5, calculating the leakage current of each single battery to be tested according to the first charging time, the second charging time, the first reference charging electric quantity and the second reference charging electric quantity; and 6, calculating the micro short circuit resistance value of each single battery to be tested according to the first voltage reference line, the second voltage reference line and the leakage current, and judging whether each single battery to be tested is a micro short circuit single battery or not according to the micro short circuit resistance value. The reference single battery is the single battery with the maximum voltage value at the charging ending time, the first voltage reference line is the median of two platform period voltage values in the first charging data, and the second voltage reference line is the median of two platform period voltage values in the second charging data.
The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack provided by the invention can also have the following characteristics: in the step 1, the working data of the lithium iron phosphate battery pack comprise voltage, current, time and temperature.
The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack provided by the invention can also have the following characteristics: in step 1, the method for positioning and referring the platform period voltage value of the single battery comprises the following steps:
the terminal voltage curve of the lithium iron phosphate battery has two obvious platform periods, the voltage change rate in a certain sampling period is calculated in the terminal voltage curve of a reference single battery, if the voltage change rate is smaller than a preset threshold value, the voltage platform period is judged, and the average value of voltage data of each platform period is taken as a corresponding platform period voltage value.
The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack provided by the invention can also have the following characteristics: in step 2, the voltage reference line is: the voltage curve of the lithium iron phosphate battery has two obvious platform periods, wherein the range of the platform periods is 35% -55% of SOC (state of charge) and 65% -95% of SOC, a voltage interval with a larger slope is arranged between the two platform periods, and a voltage reference line is positioned in the voltage interval and is a voltage median line between the two platform periods.
The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack provided by the invention can also have the following characteristics: in step 4, the calculation process of the first reference charging capacity is as follows:
CR1,i＝Qo1,i-QR1
in the formula, QR1For reference to the charge capacity, Q, of the cell during the first chargeo1,iIn the first charging process, i is 1,2, …, n is the charging capacity of other single batteries to be tested, t is the total number of the single batteries to be tested0_1For the start time of the first charging, t1_1The time for reaching the first voltage reference line is referred to; t is t2_1,iThe time of other single batteries to be tested reaching the first voltage reference line; i is the charging current of the battery pack; cR1,iThe first reference charging capacity is obtained.
The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack provided by the invention can also have the following characteristics: in step 4, the calculation process of the second reference charging capacity is as follows:
CR2,i＝Qo2,i-QR2
in the formula, QR2Referring to the charging capacity of the single battery in the second charging process; qo2,iThe charging capacity of other single batteries to be tested in the second charging process is i-1, 2, …, n, which is n single batteries to be tested; t is t0_2At the beginning of the second chargingA (c) is added; t is t1_2The time for reaching the second voltage reference line of the single battery is taken as reference; t is t2_2,iThe time of other single batteries to be tested reaching the second voltage reference line; i is the charging current of the battery pack; cR2,iA second reference charge level.
The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack provided by the invention can also have the following characteristics: in step 5, the specific process of calculating the leakage current is as follows: step 5-1, calculating a difference value between the first reference charging capacity and the second reference charging capacity to obtain the leakage capacity of each single battery to be tested in the two charging processes; step 5-2, calculating the time length between the first charging time and the second charging time of each single battery to be tested; and 5-3, calculating the ratio of the leakage amount to the time length to obtain the leakage current of each single battery to be tested.
The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack provided by the invention can also have the following characteristics: in step 6, the specific process of estimating the micro short circuit resistance value is as follows: step 6-1, calculating the average value of the first voltage reference line of each single battery to be tested and the second voltage reference line of each single battery to be tested as an average voltage; and 6-2, calculating the ratio of the average voltage to the leakage current to obtain the micro short circuit resistance value corresponding to each monomer to be tested. The method for judging and obtaining the micro short circuit monomer according to the micro short circuit resistance value comprises the following steps: and if the micro short circuit resistance value corresponding to each monomer to be detected is smaller than a preset threshold value, determining that the monomer to be detected is a micro short circuit monomer.
The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack provided by the invention can also have the following characteristics: based on the leakage current, the leakage current in a certain time is further calculated by ampere-hour integration, and the ratio of the leakage current to the theoretical electric quantity of the monomer is the self-discharge rate of the self-discharge abnormal monomer, so that the self-discharge abnormal monomer in the battery pack can be diagnosed.
Action and Effect of the invention
According to the method for diagnosing the micro short circuit monomer in the lithium iron phosphate series battery pack, firstly, the lithium iron phosphate battery pack is charged twice, and two platform-period voltage values in a voltage curve of a charging end of a reference monomer battery each time are respectively positioned according to working data of the lithium iron phosphate battery pack; then respectively acquiring a first voltage reference line and a second voltage reference line of each single battery to be tested according to the first plateau voltage value and the second plateau voltage value; then recording the time when each single battery to be tested respectively reaches the first voltage reference line and the second voltage reference line, and recording as the first charging time and the second charging time of each single battery to be tested; then, calculating a first reference charging electric quantity and a second reference charging electric quantity according to the first charging time and the second charging time; then calculating the leakage current of each single battery to be tested according to the first charging time, the second charging time, the first reference charging electric quantity and the second reference charging electric quantity; and then calculating the micro short circuit resistance value of each single battery to be tested according to the first voltage reference line, the second voltage reference line and the leakage current, and judging whether each single battery to be tested is a micro short circuit single battery or not according to the micro short circuit resistance value. The reference single battery is the single battery with the maximum voltage value at the charging ending time, the first voltage reference line is the median of two platform period voltage values in the first charging data, and the second voltage reference line is the median of two platform period voltage values in the second charging data.
The diagnosis method is quick and simple, the single battery with the micro short circuit in the battery pack can be diagnosed with small calculation amount only based on two or more times of historical charging data, and the accurate micro short circuit estimated resistance value can be obtained. In addition, the invention does not depend on the overall data of the battery pack, is not influenced by the inconsistency of the battery pack and the like, and the diagnosis results are not influenced mutually even if the micro short circuit degrees of the single bodies are different according to the comparison of the historical data of the single bodies. Thereby providing reference for subsequent system alarming or coping measures and the like.
In addition, the diagnosis method of the invention has strong adaptability, is not limited to the charging and discharging use conditions of full charge and full discharge, is not influenced by temperature, charging condition, battery life and the like, and can embody a more accurate estimation value no matter under the situations of 1/3C constant current charging or 1C constant current charging and the like, thereby improving the safety, the dynamic property and the durability of the battery pack.
In addition, the diagnosis method has wide application field, and can be used for diagnosing the micro-short-circuit monomer in the lithium iron phosphate series battery pack and accurately monitoring the self-discharge abnormal monomer.
Drawings
Fig. 1 is a schematic view of a lithium iron phosphate series battery pack according to an embodiment of the present invention;
fig. 2 is a flowchart of a method for diagnosing micro short-circuit cells in a lithium iron phosphate series battery pack according to an embodiment of the present invention;
fig. 3 is an OCV-SOC curve of a lithium iron phosphate unit cell used in an embodiment of the present invention;
fig. 4 is a schematic diagram of a charging voltage curve of a single battery of the lithium iron phosphate series battery pack in the embodiment of the invention.
Detailed Description
In order to make the technical means, creation features, achievement objectives and effects of the present invention easy to understand, the following embodiments are specifically set forth a method for diagnosing a micro short-circuit monomer in a lithium iron phosphate series battery pack according to the present invention with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of the lithium iron phosphate series battery in this example.
As shown in fig. 1, in this embodiment, two LP27148134-40Ah lithium iron phosphate batteries manufactured by tianjin dynasty battery gmbh are arbitrarily selected to be connected in series to form a group, and a resistor with a resistance of 100 Ω is randomly connected in parallel outside one battery to simulate the situation of micro short circuit of a single body.
Fig. 2 is a flowchart of a method for diagnosing a micro short-circuit cell in a lithium iron phosphate series battery pack according to the present embodiment.
As shown in fig. 2, the method for diagnosing a micro short-circuit cell in a lithium iron phosphate series battery according to the present embodiment includes the following steps:
and step S1, charging the lithium iron phosphate battery pack twice, and respectively positioning two platform period voltage values in a voltage curve of each charging terminal of the reference single battery according to the working data of the lithium iron phosphate battery pack.
The battery pack operation data used in the present embodiment includes at least two charging data (voltage, current, time, temperature, etc.), and is not limited to two consecutive charges. The terminal voltage curve of the lithium iron phosphate battery has two obvious platform periods, and the platform period voltage value of the same reference monomer can be changed due to the fact that the situation that the charging working conditions are different for two times possibly exists, so that the platform period of the charging terminal voltage at each time needs to be positioned. In the present embodiment, in a terminal voltage curve of a reference cell, a plateau position is roughly determined by calculating a voltage change rate in a certain sampling period. And if the voltage change rate is less than the preset threshold value of 0.3mv, judging the voltage plateau period, and taking the average value of the voltage data of each plateau period as the corresponding voltage value.
In addition, the reference cell is considered to be the cell with the maximum voltage value at the charging end time, and is not limited to the full-charge condition. Furthermore, even if a certain self-discharge condition occurs in the later stage of the reference monomer, the method of the embodiment still cannot be influenced.
Step S2, respectively obtaining a first voltage reference line and a second voltage reference line of each single battery to be tested according to the first plateau voltage value and the second plateau voltage value.
Fig. 3 is an OCV-SOC curve of the lithium iron phosphate single cell used in this example.
As shown in fig. 3, the OCV-SOC curve at 25 ℃ of the lithium iron phosphate battery used in the present example is shown. It is easy to see that the ranges of the two obvious platform periods are 35% -55% SOC and 65% -95% SOC, a voltage interval with a larger slope is also arranged between the two platforms, and a voltage reference line is positioned in the voltage interval and is a voltage median line of the two platforms. According to the use habit of most users, the electric quantity at the moment of charging the battery must include two voltage plateaus, at least one section of the two plateaus. Thus, the method of the embodiment can still be normally used even if the user is in the condition of not full charge and full discharge.
Step S3, recording the time when each of the to-be-tested single batteries respectively reaches the first voltage reference line and the second voltage reference line, and recording the time as the first charging time and the second charging time of each of the to-be-tested single batteries.
In step S4, a first reference charging capacity and a second reference charging capacity are calculated according to the first charging time and the second charging time.
Fig. 4 is a graph illustrating the charging voltage curve of the unit cells of the lithium iron phosphate series battery in this embodiment. Wherein (a) and (b) are a first charge and a second charge, respectively.
Fig. 4 is a schematic diagram of a two-time charging voltage curve in the present embodiment, and the details are described with reference to fig. 4(a) as an example. Wherein, U1The single cell which reaches the first voltage reference line firstly serves as a reference single cell, and the other single cell serves as a single cell to be tested. t is t1_1The time for reaching the first voltage reference line is referred to; t is t2_1The time for the single battery to be measured to reach the first voltage reference line is obtained. The first reference electric quantity is further calculated according to the following formula.
CR1＝Qo1-QR1
Wherein Q isR1Referring to the charging capacity of the single battery in the first charging process; qo1The charging capacity of the single battery to be tested in the first charging process (in this embodiment, only one single battery is included, so Q is directly usedo1Represents); t is t0_1A start time for a first charge; i is the charging current of the battery pack; cR1The first reference charging capacity is obtained.
In this embodiment, Q is calculatedR1Is 22.7627Ah, Qo123.0699Ah, the first reference charging capacity CR10.3071 Ah. The second reference charge can be obtained in the same wayElectric quantity CR2It was 0.4774 Ah.
Step S5, calculating the leakage current of each cell to be tested according to the first charging time, the second charging time, the first reference charging capacity and the second reference charging capacity.
And step S5-1, calculating the difference value between the first reference charging capacity and the second reference charging capacity to obtain the leakage capacity of each single battery to be tested in the two charging processes to be 0.2294 Ah.
And step S5-2, calculating the time length between the first charging time and the second charging time of each single battery to be tested.
And step S5-3, calculating the ratio of the leakage current to the time length, namely the leakage current of each single battery to be tested is 0.0249A.
Step S6, calculating a micro short circuit resistance value of each single battery to be tested to be about 135.0292 Ω according to the first voltage reference line, the second voltage reference line and the leakage current, and determining whether each single battery to be tested is a micro short circuit single battery according to the micro short circuit resistance value.
Since the actual capacities of the two battery cells used in this embodiment are 41.2196Ah and 41.2196Ah, respectively. It can be seen that the capacities of the two batteries have a certain difference, so that the resistance value can be estimated for the first time by the influence of factors such as the capacity difference between the single batteries. Further, in the present example, three charge-discharge cycles were continued. Three other groups of micro short circuit resistances are obtained, namely 99.3221 omega, 118.0912 omega and 113.0524 omega. Obviously, the estimation value of the method can reach certain precision. And judging whether the monomer is a micro short circuit monomer or not according to the micro short circuit resistance value.
Effects and effects of the embodiments
According to the method for diagnosing the micro short circuit monomer in the lithium iron phosphate series battery pack, firstly, the lithium iron phosphate battery pack is charged twice, and two platform-period voltage values in a voltage curve of a charging end of a reference monomer battery each time are respectively positioned according to working data of the lithium iron phosphate battery pack; then respectively acquiring a first voltage reference line and a second voltage reference line of each single battery to be tested according to the first plateau voltage value and the second plateau voltage value; then recording the time when each single battery to be tested respectively reaches the first voltage reference line and the second voltage reference line, and recording as the first charging time and the second charging time of each single battery to be tested; then, calculating a first reference charging electric quantity and a second reference charging electric quantity according to the first charging time and the second charging time; then calculating the leakage current of each single battery to be tested according to the first charging time, the second charging time, the first reference charging electric quantity and the second reference charging electric quantity; and then calculating the micro short circuit resistance value of each single battery to be tested according to the first voltage reference line, the second voltage reference line and the leakage current, and judging whether each single battery to be tested is a micro short circuit single battery or not according to the micro short circuit resistance value. The reference single battery is the single battery with the maximum voltage value at the charging ending time, the first voltage reference line is the median of two platform period voltage values in the first charging data, and the second voltage reference line is the median of two platform period voltage values in the second charging data.
The diagnosis method is quick and simple, the single battery with the micro short circuit in the battery pack can be diagnosed with a small calculation amount only based on two times of historical charging data, and a relatively accurate micro short circuit estimated resistance value can be obtained. In addition, the present embodiment does not depend on the data of the entire battery pack, is not affected by the inconsistency of the battery pack, and the diagnosis results will not be affected by each other even if the degree of the micro short circuit of each cell is different, only by comparing the historical data of each cell. Thereby providing reference for subsequent system alarming or coping measures and the like.
In addition, the diagnosis method of the embodiment has strong adaptability, is not limited to the charging and discharging use conditions of full charge and full discharge, is not influenced by temperature, charging condition, battery life and the like, and can embody a relatively accurate estimation value no matter in the situations of 1/3C constant current charging or 1C constant current charging and the like, so that the safety, the power performance and the durability of the battery pack are improved.
In addition, the diagnosis method of the embodiment has wide application field, and besides the diagnosis of the micro-short-circuit monomer in the lithium iron phosphate series battery pack, the method of the embodiment can also be applied to the accurate monitoring of the self-discharge abnormal monomer.
The above embodiments are preferred examples of the present invention, and are not intended to limit the scope of the present invention.
Claims (9)
1. A method for diagnosing a micro short-circuit monomer in a lithium iron phosphate series battery pack is characterized by comprising the following steps:
step 1, charging a lithium iron phosphate battery pack twice, and respectively positioning two platform-period voltage values in a voltage curve of a charging end of a single battery according to working data of the lithium iron phosphate battery pack;
step 2, respectively acquiring a first voltage reference line and a second voltage reference line of each single battery to be tested according to the first platform period voltage value and the second platform period voltage value;
step 3, recording the time of each single battery to be tested reaching the first voltage reference line and the second voltage reference line respectively, and recording as the first charging time and the second charging time of each single battery to be tested;
step 4, calculating a first reference charging electric quantity and a second reference charging electric quantity according to the first charging time and the second charging time;
step 5, calculating the leakage current of each single battery to be tested according to the first charging time, the second charging time, the first reference charging capacity and the second reference charging capacity;
step 6, calculating the micro short circuit resistance value of each single battery to be tested according to the first voltage reference line, the second voltage reference line and the leakage current, judging whether each single battery to be tested is a micro short circuit single battery or not according to the micro short circuit resistance value,
wherein the reference single battery is the single battery with the maximum voltage value at the charging end time,
the first voltage reference line is the median of the two plateau voltage values in the first charging data,
the second voltage reference line is a median of the two plateau voltage values in the second charging data.
2. The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack according to claim 1, wherein the method comprises the following steps:
in the step 1, the working data of the lithium iron phosphate battery pack comprise voltage, current, time and temperature.
3. The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack according to claim 1, wherein the method comprises the following steps:
in step 1, the method for positioning and referring the platform period voltage value of the single battery comprises the following steps:
the terminal voltage curve of the lithium iron phosphate battery has two obvious platform periods, the voltage change rate in a certain sampling period is calculated in the terminal voltage curve of a reference single battery, if the voltage change rate is smaller than a preset threshold value, the voltage platform period is judged, and the average value of voltage data of each platform period is taken as a corresponding platform period voltage value.
4. The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack according to claim 1, wherein the method comprises the following steps:
in step 2, the voltage reference line is:
the voltage curve of the lithium iron phosphate battery has two obvious platform periods, wherein the range of the platform periods is 35% -55% SOC and 65% -95% SOC, a voltage interval with a larger slope is arranged between the two platform periods, and the voltage reference line is positioned in the voltage interval and is a voltage median line between the two platform periods.
5. The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack according to claim 1, wherein the method comprises the following steps:
in step 4, the calculation process of the first reference charging capacity is as follows:
CR1,i＝Qo1,i-QR1
in the formula, QR1For reference to the charge capacity, Q, of the cell during the first chargeo1,iIn the first charging process, i is 1,2, …, n is the charging capacity of other single batteries to be tested, t is the total number of the single batteries to be tested0_1For the start time of the first charging, t1_1The time for reaching the first voltage reference line is referred to; t is t2_1,iThe time of other single batteries to be tested reaching the first voltage reference line; i is the charging current of the battery pack; cR1,iThe first reference charging capacity is obtained.
6. The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack according to claim 1, wherein the method comprises the following steps:
in step 4, the calculation process of the second reference charging capacity is as follows:
CR2,i＝Qo2,i-QR2
in the formula, QR2Referring to the charging capacity of the single battery in the second charging process; qo2,iThe charging capacity of other single batteries to be tested in the second charging process is i-1, 2, …, n, which is n single batteries to be tested; t is t0_2A start time for the second charge; t is t1_2The time for reaching the second voltage reference line of the single battery is taken as reference; t is t2_2,iReaching a second voltage base for other single batteries to be testedTime of alignment; i is the charging current of the battery pack; cR2,iA second reference charge level.
7. The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack according to claim 1, wherein the method comprises the following steps:
in step 5, the specific process of calculating the leakage current is as follows:
step 5-1, calculating a difference value between the first reference charging capacity and the second reference charging capacity to obtain the leakage capacity of each single battery to be tested in the two charging processes;
step 5-2, calculating the time length between the first charging time and the second charging time of each single battery to be tested;
and 5-3, calculating the ratio of the leakage current to the time length, namely the leakage current of each single battery to be tested.
8. The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack according to claim 1, wherein the method comprises the following steps:
in step 6, the specific process of estimating the micro short circuit resistance value is as follows:
step 6-1, calculating the average value of the first voltage reference line of each single battery to be tested and the second voltage reference line of each single battery to be tested as an average voltage;
step 6-2, calculating the ratio of the average voltage to the leakage current to obtain the micro short circuit resistance value corresponding to each monomer to be tested,
the method for judging and obtaining the micro short circuit monomer according to the micro short circuit resistance value comprises the following steps:
and if the micro short circuit resistance value corresponding to each monomer to be detected is smaller than a preset threshold value, determining that the monomer to be detected is a micro short circuit monomer.
9. The method for diagnosing the micro short-circuit monomer in the lithium iron phosphate series battery pack according to claim 1, wherein the method comprises the following steps:
and on the basis of the leakage current, further calculating the leakage current for a certain time by ampere-hour integration, wherein the ratio of the leakage current to the theoretical electric quantity of the monomer is the self-discharge rate of the self-discharge abnormal monomer, so that the self-discharge abnormal monomer in the battery pack can be diagnosed.
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| US20140163853A1 (en) * | 2012-12-12 | 2014-06-12 | GM Global Technology Operations LLC | Plug-in charge capacity estimation method for lithium iron-phosphate batteries |
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| CN106443478A (en) * | 2016-10-26 | 2017-02-22 | 河南师范大学 | Lithium iron phosphate battery rest electric quantity estimation method based on closed-loop hybrid algorithm |
| CN108152755A (en) * | 2018-01-19 | 2018-06-12 | 上海理工大学 | The method of online quantitative Diagnosis battery micro-short circuit failure |
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