CN116520168A - Capacity consistency detection method, device, vehicle and medium of battery system - Google Patents

Abstract

The application provides a method for detecting capacity consistency of a battery system, which comprises the following steps: charging the battery system, and carrying out secondary charging on the battery system under the condition that the open circuit voltage of the battery system charged to the target battery cell monomer meets the charging cut-off condition; acquiring a first open-circuit voltage of each battery cell in the battery system under the condition that the battery system is charged for the second time until the open-circuit voltage of the target battery cell meets a charge cut-off condition; discharging the battery system, and acquiring a second open-circuit voltage of each battery cell under the condition that the open-circuit voltage of the battery system discharged to the target battery cell meets a discharge cut-off condition; and acquiring the monomer capacity of each cell unit based on the first open-circuit voltage and the second open-circuit voltage, and determining the capacity consistency of the battery system based on the monomer capacity of each cell unit.

Description

Capacity consistency detection method, device, vehicle and medium of battery system

technical field

The present application relates to the field of battery technology, and in particular to a method, device, vehicle and medium for detecting capacity consistency of a battery system.

Background technique

With the increasing popularity of electric vehicles, lithium-ion batteries have become an important part of the drive system of electric vehicles due to their own advantages such as high energy density, good cycle performance, low self-discharge rate and no memory effect. The battery system as an electric vehicle drive system is usually composed of multiple battery cells of the same type. Due to the differences in capacity, voltage, internal resistance, self-discharge rate, etc. of the battery cells, especially the battery cells The difference in capacity consistency leads to the fact that the discharge capacity of the battery system used in the electric vehicle often cannot reach the original level of the battery cell, which seriously affects the cruising range of the electric vehicle. At present, the test of the battery system is usually carried out for the battery system as a whole, and it is difficult to evaluate the consistency difference of the capacity of all battery cells in the battery system.

Contents of the invention

The embodiment of the present application provides a battery system capacity consistency detection method, device, vehicle and medium to solve the problem that it is difficult to evaluate the consistency difference of the capacity of all battery cells in the battery system in the prior art.

In order to solve the above-mentioned technical problems, the application is implemented as follows:

In the first aspect, an embodiment of the present application provides a method for detecting capacity consistency of a battery system, the method comprising:

Charge the battery system, and recharge the battery system when the battery system is charged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition, wherein the target battery cell Any single cell in the cell system;

Acquiring the first open circuit voltage of each battery cell in the battery system when the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition;

Discharging the battery system, and obtaining the second open circuit voltage of each battery cell when the battery system is discharged until the open circuit voltage of the target battery cell meets the discharge cut-off condition;

Obtaining the cell capacity of each battery cell based on the first open circuit voltage and the second open circuit voltage, and determining the cell capacity of the battery system based on the cell capacity of each cell cell Capacity Consistency.

Optionally, the charging the battery system includes:

controlling the battery system to stand for a first period of time within a preset temperature range;

Discharging the battery system at a preset discharge rate;

When the battery system is discharged until the open circuit voltage of the target battery cell satisfies the discharge cut-off condition, controlling the battery system to stand still in a preset temperature range for a first duration;

The battery system is charged at a preset first charging rate.

Optionally, when the battery system is charged to the point where the open-circuit voltage of the target battery cell satisfies the charging cut-off condition, performing secondary charging on the battery system includes:

In the case that the open circuit voltage of the target battery cell satisfies the charging cut-off condition, controlling the battery system to stand still for a second duration, wherein the second duration is shorter than the first duration;

Secondary charging is performed on the battery system at a preset second charging rate.

Optionally, when the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charge cut-off condition, acquiring the first value of each battery cell in the battery system Open circuit voltage, including:

When the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition, the battery system is controlled to stand still in a preset temperature range for a third period of time, wherein the a third duration is longer than the second duration and shorter than the first duration;

Obtaining the first open circuit voltage of each battery cell in the battery system;

The obtaining the second open circuit voltage of each battery cell when the battery system is discharged to the open circuit voltage of the target battery cell meeting the discharge cut-off condition includes:

When the battery system is discharged until the open-circuit voltage of the target cell meets the discharge cut-off condition, controlling the battery system to stand still in the preset temperature range for the third duration;

Acquiring the second open circuit voltage of each battery cell in the battery system.

Optionally, after acquiring the second open circuit voltage of each battery cell, the method further includes:

Obtaining the first capacity of each battery cell, wherein the first capacity is a single discharge capacity of the battery system, and the cell capacity of the battery cell is determined based on the first capacity.

Optionally, the obtaining the cell capacity of each battery cell based on the first open circuit voltage and the second open circuit voltage includes:

Obtain the mapping relationship between the state of charge and the open circuit voltage;

Based on the first open circuit voltage and the mapping relationship, obtain the first state of charge of each battery cell, and based on the second open circuit voltage and the mapping relationship, obtain the each battery cell the second state of charge of the monomer;

Based on the first capacity, the first state of charge and the second state of charge, the cell capacity of each battery cell is obtained.

Optionally, the determining the capacity consistency of the battery system based on the cell capacity of each battery cell includes:

Obtain the preset discharge capacity and capacity consistency parameters of the battery cells of the battery system;

Acquiring the target cell capacity of the battery cell, wherein the target cell capacity is the minimum cell capacity of the battery cell in the battery system;

determining a target capacity interval based on the target cell capacity and the capacity consistency parameter;

When the target cell capacity is greater than or equal to the preset discharge capacity, judging whether the cell capacity of each battery cell is within the target capacity range;

In a case where the cell capacity of each battery cell is within the target capacity interval, it is determined that the capacity consistency of the battery system is qualified.

In the second aspect, the present application also provides a capacity consistency detection device for a battery system, the device comprising:

The first charging module is configured to charge the battery system, and recharge the battery system when the battery system is charged until the open circuit voltage of the target cell meets the charging cut-off condition, wherein, The target battery cell is any one of the battery cells in the battery system;

The second charging module is configured to obtain the second charge of each battery cell in the battery system when the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition - open circuit voltage;

The discharge module is used to discharge the battery system, and obtain the second voltage of each battery cell when the battery system is discharged to the open circuit voltage of the target battery cell meeting the discharge cut-off condition. open circuit voltage;

A determining module, configured to obtain the cell capacity of each battery cell based on the first open circuit voltage and the second open circuit voltage, and determine the cell capacity based on the cell capacity of each cell cell The capacity consistency of the battery system.

In a third aspect, the present application also provides a vehicle, the vehicle includes a processor and a memory, the memory stores programs or instructions that can run on the processor, and when the programs or instructions are executed by the processor The steps of realizing the capacity consistency detection method of a battery system according to any one of the first aspect.

In the fourth aspect, the present application also provides a computer-readable storage medium, on which a program or instruction is stored, and when the program or instruction is executed by a processor, it can realize any one of the first aspect. The steps of a method for detecting capacity consistency of a battery system.

In the embodiment of the present application, by obtaining the open circuit voltage of the battery system in the fully charged and discharged states, the capacity of each cell in the battery system can be determined, and finally the capacity consistency of the battery system can be determined. On the basis of not adding additional test items, only charge and discharge the battery system to determine whether each cell in the battery system meets the capacity consistency standard, so as to determine whether the capacity consistency of the battery system is qualified, which can effectively eliminate capacity consistency Poor battery cells.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that need to be used in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on these drawings without any creative effort.

FIG. 1 is one of the flowcharts of a method for detecting capacity consistency of a battery system provided in an embodiment of the present application;

Fig. 2 is the second flow chart of a battery system capacity consistency detection method provided by the embodiment of the present application;

Fig. 3 is the third flowchart of a battery system capacity consistency detection method provided by the embodiment of the present application;

Fig. 4 is the detection result of the capacity consistency of the lithium iron phosphate battery system in the embodiment of the present application;

Fig. 5 is the detection result of the capacity consistency of the ternary polymer lithium battery system in the embodiment of the present application;

FIG. 6 is a schematic structural diagram of a capacity consistency detection device for a battery system provided in an embodiment of the present application;

Fig. 7 is a schematic structural diagram of a vehicle provided by an embodiment of the present application.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

Embodiments of the present application provide a battery system capacity consistency detection method, device, vehicle, and medium. Referring to FIG. 1, FIG. 1 is one of the flow charts of a method for detecting capacity consistency of a battery system provided in an embodiment of the present application. The method includes the following steps:

S101. Charge the battery system. When the battery system is charged until the open-circuit voltage of the target cell meets the charging cut-off condition, recharge the battery system, wherein the target cell A single cell is any single cell in the cell system.

In a specific implementation, the above-mentioned battery system may be a lithium-ion battery that is convenient for charging and discharging, specifically, it may be a battery system that can be used as a power system of an electric vehicle, such as a lithium iron phosphate battery, a ternary polymer lithium battery, etc. The battery system used in this application The types are not limited and can be used according to actual needs. The battery system of the present application includes a plurality of battery cells, and under the joint charge and discharge of the multiple battery cells, the vehicle is driven. In addition, the above-mentioned charging cut-off condition can be a specific voltage parameter set in advance. For example, charging the battery system can be determined by judging whether there is an open-circuit voltage of a battery cell that is greater than the parameter value set by the charging cut-off condition. Whether the battery system is fully charged.

S102. Acquire a first open circuit voltage of each battery cell in the battery system when the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition.

In the above steps, the first open circuit voltage may be the terminal voltage of the battery cell in a fully charged state and under an open circuit condition, and the maximum state of charge of the corresponding battery cell may be reflected by the first open circuit voltage.

In the specific implementation, the battery system needs to be charged twice, and the battery system is charged again after the first charge reaches the charge cut-off condition, so that there is a target cell in the battery system whose open circuit voltage is greater than the charge cut-off condition . The double charging can prevent the battery cells in the battery system from backflow or leakage after the first charge due to differences in capacity, energy, power, and service life, which can make the battery cells in the battery system reach full charge.

S103. Discharge the battery system, and obtain a second open circuit voltage of each battery cell when the battery system is discharged until the open circuit voltage of the target battery cell satisfies a discharge cut-off condition.

It should be noted that the above-mentioned discharge cut-off condition can also be a preset voltage parameter. For example, after the battery system is discharged, it can be judged whether there is an open-circuit voltage of a cell in the battery that is lower than the discharge cut-off condition. Voltage parameters, so that it can be judged whether the battery system is fully discharged. In addition, the second open-circuit voltage may be the terminal voltage of the battery cell in a state of being discharged and under an open-circuit condition, and the minimum state of charge of the corresponding battery cell may be reflected by the second open-circuit voltage.

In the above steps, the battery system is discharged after the battery system is fully charged, and the battery system is discharged until the open circuit voltage of the target battery cell meets the discharge cut-off condition, that is, the battery system is discharged. When the battery system is completely discharged, the second open-circuit voltage of each battery cell is measured and obtained at this time.

S104. Based on the first open circuit voltage and the second open circuit voltage, obtain the cell capacity of each battery cell, and determine the battery based on the cell capacity of each cell cell System capacity consistency.

It should be understood that the above-mentioned acquisition of the cell capacity of the battery cell based on the first open circuit voltage and the second open circuit voltage may firstly determine the cell capacity of each cell cell through the first open circuit voltage and the second open circuit voltage of each cell cell. The maximum state of charge and the minimum state of charge of the body, the difference between the maximum state of charge and the minimum state of charge is determined as the state of charge difference of the battery cell, and the actual capacity of the battery cell obtained in advance through comprehensive value to determine the cell capacity of the battery cell, which can be obtained by the following formula:

Among them, Q _X is the monomer capacity of any battery cell;

Q is the pre-acquired single discharge capacity value of the battery cell;

Soc is the maximum state of charge corresponding to the first open circuit voltage of the battery cell;

Soc' is the minimum state of charge corresponding to the second open circuit voltage of the battery cell.

In the above steps, the capacity consistency of the battery system is determined based on the capacity of each battery cell. Specifically, it may be: after determining the cell capacity of each battery cell, determine the battery capacity of the battery system. The minimum cell capacity of a cell, the minimum cell capacity is used to determine the capacity consistency index, and when the cell capacity of each battery cell is within this index, it indicates that the capacity consistency of the battery system is qualified .

In the embodiment of the present application, firstly, the battery system is charged until the open circuit voltage of a single battery cell in the battery system reaches the charging cut-off condition, and the battery system is recharged again to keep the battery cells fully charged. The state is convenient for determining the first open circuit voltage of the battery cell in the fully charged state. Subsequently, the battery system is discharged until the open-circuit voltage of the target battery cell reaches the discharge cut-off condition, and at this time, the second open-circuit voltage of the battery cell in an empty state is determined. Determine the maximum capacity value and the minimum capacity value of each battery cell based on the first open circuit voltage and the second open circuit voltage to determine the cell capacity of each battery cell. Finally, compare the individual capacity of each battery cell with the capacity consistency index to comprehensively determine the capacity consistency of the battery system.

This application can obtain the single capacity of each battery cell in the battery system only through the above-mentioned charging, secondary charging and discharging process without adding other testing methods, so as to evaluate and determine the capacity consistency of the battery system, and can Reduce test costs, improve evaluation efficiency, and promptly eliminate battery systems with unqualified capacity consistency.

As an optional implementation manner, the charging the battery system includes:

controlling the battery system to stand for a first period of time within a preset temperature range;

Discharging the battery system at a preset discharge rate;

When the battery system is discharged until the open circuit voltage of the target battery cell satisfies the discharge cut-off condition, controlling the battery system to stand still in a preset temperature range for a first duration;

The battery system is charged at a preset first charging rate.

It should be understood that the battery system is controlled to stand still for a first period of time within the preset temperature range, so that the battery system can perform charge and discharge tests in a normal state, and prevent the extreme temperature from affecting the battery system from too much interference to the detection effect of the battery system capacity consistency. . Discharge the battery system at a preset discharge rate, so that the battery system can be discharged under a constant current and stable state, reducing the interference of unstable factors on the detection of the capacity of the battery system. In addition, the above-mentioned target battery cell can be any battery cell in the battery system. When the battery system is discharged until the open circuit voltage of the target battery cell satisfies the discharge cut-off condition, that is, there is an open circuit voltage of one battery cell. Satisfy the discharge cut-off condition. In a specific implementation, the battery system is first discharged and then the battery system is left to stand, so that the battery system can maintain a stable state after being discharged, so that the battery system can be charged later.

As an optional implementation manner, when the battery system is charged to the point where the open-circuit voltage of the target battery cell satisfies the charging cut-off condition, performing secondary charging on the battery system includes:

In the case that the open circuit voltage of the target battery cell satisfies the charging cut-off condition, controlling the battery system to stand still for a second duration, wherein the second duration is shorter than the first duration;

Secondary charging is performed on the battery system at a preset second charging rate.

Specifically, after the battery system is fully charged for the first time, the battery system is left to stabilize, so that the battery system can be stabilized. At this time, the battery system will be depolarized, the voltage will drop, and the battery cells will no longer meet the charging cut-off conditions. Subsequently, the battery system is charged for the second time at a preset second rate smaller than the preset first charge rate, so that the open circuit voltage of the battery cell in the battery system can meet the charge cut-off condition again, so that the battery can be stabilized system, so that the battery system is stably in a fully charged state.

As an optional implementation manner, when the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition, the acquisition of each battery cell in the battery system The first open circuit voltage of the monomer, including:

When the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition, the battery system is controlled to stand still in a preset temperature range for a third period of time, wherein the a third duration is longer than the second duration and shorter than the first duration;

Obtaining the first open circuit voltage of each battery cell in the battery system;

The obtaining the second open circuit voltage of each battery cell when the battery system is discharged to the open circuit voltage of the target battery cell meeting the discharge cut-off condition includes:

When the battery system is discharged until the open-circuit voltage of the target cell meets the discharge cut-off condition, controlling the battery system to stand still in the preset temperature range for the third duration;

Acquiring the second open circuit voltage of each battery cell in the battery system.

In specific implementation, after recharging the battery, the battery system needs to be left still within a preset temperature range to reduce the temperature rise of the battery system due to charging, so that the battery system tends to be stable and does not occur in a discharged state. After the battery system is in a stable state, the first open circuit voltage of each battery cell in the battery system is measured in time, and the first open circuit voltage measured at this time can more accurately reflect the maximum charging capacity of the battery cell. Please refer to FIG. 2 in detail. In the specific embodiment of obtaining the first open circuit voltage and the second open circuit voltage in this application, the following steps may be specifically included:

Step 201. Control the battery system to stand still for a first duration within a preset temperature range.

Specifically, the first duration can be set within a range of 8 to 16 hours, and the battery system can be left standing for 16 hours at an ambient temperature of 25°C±2°C.

Step 202. Discharge the battery system at a preset discharge rate.

Step 203 , judging whether the open circuit voltage of the target cell meets the discharge cut-off condition.

Step 204 , when the battery system is discharged until the open circuit voltage of the target battery cell satisfies the discharge cut-off condition, control the battery system to stand still in the preset temperature range for a first time period again. When the open-circuit voltage of the target battery cell does not meet the discharge cut-off condition, the battery system continues to discharge.

In a specific implementation, the preset discharge rate can be set within the rate range from 0.25C to 0.5C, and the battery system can be discharged at a constant current of 0.25C. When there is a battery cell in the battery system, that is, the above-mentioned target battery cell, stop discharging when the open circuit voltage of the target battery cell meets the cell full-window discharge cut-off condition, and let the battery system stand still for 180 minutes. Subsequently, the battery system may be left to stand for a first period of time at an ambient temperature of 25°C±2°C, so that the difference between the temperature of the battery cells and the preset environmental problem is not higher than 2°C.

Step 205, charging the battery system at a preset first charging rate.

Step 206 , judging whether the open circuit voltage of the target battery cell satisfies the charging cut-off condition.

Step 207 , when the open circuit voltage of the target battery cell satisfies the charging cut-off condition, control the battery system to stand still for a second duration. When the open-circuit voltage of the target battery cell does not satisfy the charging cut-off condition, the battery system is charged again at a preset first charging rate.

In the above steps, the preset first charging rate can be set within the rate range of 0.25C to 0.5C, the battery system can be charged at a charging rate of 0.25C, and the second duration can be set between 5 seconds and 300 seconds within the interval. Subsequently, when the open-circuit voltage of the target battery cell in the battery system meets the charging cut-off condition, the battery system is left to stand for 300 seconds.

Step 208 , recharging the battery system at a preset second charging rate.

Step 209 , judging again whether the open circuit voltage of the target cell meets the charging cut-off condition.

Step 210 , when the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition, acquire a first open circuit voltage of each battery cell in the battery system.

Specifically, after standing still, it can switch to a small current to charge the battery system. The preset second charging rate can be set within the range of 0.01C to 0.05C. The battery system can be recharged at a charge rate of 0.05C. When the battery system is charged until the open circuit voltage of the target battery cell meets the charging cut-off condition, record the first open circuit voltage of each battery cell.

Step 211, performing secondary discharge on the battery system at a preset discharge rate.

Step 212 , judging whether the open circuit voltage of the target cell meets the discharge cut-off condition.

Step 213: When the battery system is discharged a second time until the open-circuit voltage of the target battery cell satisfies the discharge cut-off condition, control the battery system to stand still for a third period of time within a preset temperature range, and Obtain the second open-circuit voltage of each battery cell. When the battery system is discharged a second time until the open circuit voltage of the target battery cell does not satisfy the discharge cut-off condition, the battery system is continuously discharged for a second time.

In the specific implementation steps, before discharging the battery system for the second time, the battery system can be placed at an ambient temperature of 25°C±2°C for a first period of time, so that the difference between the temperature of the battery system and the ambient temperature does not exceed 2°C. Subsequently, the battery system can be discharged at a rate of 0.25C until the open circuit voltage of the target battery cell meets the cell full-window discharge cut-off condition. In addition, the third duration may be set within a range of 30 minutes to 180 minutes. In the case that the open circuit voltage of the target battery cell meets the discharge cut-off condition, after the battery system is left standing for a third period of time, the second open circuit voltage of each battery cell is recorded.

Continuing to refer to Figure 2, through the process of discharging, charging, recharging, and redischarging the battery system in the above steps, the first open-circuit voltage of each battery cell in the battery system representing the maximum state of charge is obtained, and the expression The second open circuit voltage of the minimum state of charge.

As an optional implementation manner, after obtaining the second open circuit voltage of each battery cell, further include:

Obtaining the first capacity of each battery cell, wherein the first capacity is a single discharge capacity of the battery system, and the cell capacity of the battery cell is determined based on the first capacity.

It is worth mentioning that the first capacity in this application can be the single discharge capacity of the battery system, and the single capacity of the battery cell can be obtained through the first capacity, the first open circuit voltage and the second open circuit voltage, and the specific calculation The formula has been described above and will not be repeated here.

As an optional implementation manner, the obtaining the cell capacity of each battery cell based on the first open circuit voltage and the second open circuit voltage includes:

Obtain the mapping relationship between the state of charge and the open circuit voltage;

Based on the first open circuit voltage and the mapping relationship, obtain the first state of charge of each battery cell, and based on the second open circuit voltage and the mapping relationship, obtain the each battery cell the second state of charge of the monomer;

Based on the first capacity, the first state of charge and the second state of charge, the cell capacity of each battery cell is obtained.

In a specific implementation, the above-mentioned mapping relationship between the state of charge and the open circuit voltage may be provided by a single battery cell, and may be expressed as a mapping relationship between the state of charge and the open circuit voltage. Through this mapping relationship, the state of charge, that is, the actual display capacity of the battery cell can be determined based on the open circuit voltage. The above-mentioned first state of charge may be the maximum state of charge corresponding to the first open circuit voltage, and the second state of charge may be the minimum state of charge corresponding to the second open circuit voltage. Then, the cell capacity of each battery cell is obtained through the difference between the first state of charge and the second state of charge, and the first capacity. For details, please refer to the following formula:

Among them, Q _X is the monomer capacity of any battery cell;

Q is the first capacity, that is, the single discharge capacity value of the battery system;

Soc _x is the first state of charge;

Soc' _x is the second state of charge.

As an optional implementation manner, the determining the capacity consistency of the battery system based on the cell capacity of each battery cell includes:

Obtain the preset discharge capacity and capacity consistency parameters of the battery cells of the battery system;

Acquiring the target cell capacity of the battery cell, wherein the target cell capacity is the minimum cell capacity of the battery cell in the battery system;

determining a target capacity interval based on the target cell capacity and the capacity consistency parameter;

When the target cell capacity is greater than or equal to the preset discharge capacity, judging whether the cell capacity of each battery cell is within the target capacity interval;

In a case where the cell capacity of each battery cell is within the target capacity interval, it is determined that the capacity consistency of the battery system is qualified.

In the above embodiments, the target capacity range is determined based on the existing preset discharge capacity of the battery system and the capacity consistency parameters determined according to actual test requirements. The target capacity range can be used as an index to measure whether the capacity of the battery cell meets the capacity consistency standard, and can accurately determine whether the battery cell in the battery system is qualified or not, so as to facilitate the timely elimination of cells that do not meet the capacity consistency standard Monomer can also reduce the testing cost of capacity consistency.

In addition, the target cell capacity obtained above is the minimum cell capacity of the battery cell in the battery system, and the target cell capacity may be the smallest difference between the first open circuit voltage and the second open circuit voltage of the cell cell The value can be the minimum charge and discharge capacity value of the battery cell in the battery system. By judging whether the capacity of the battery system satisfies the preset discharge capacity as the first standard for measuring whether the capacity consistency of the battery system is qualified, the capacity consistency detection result can be determined more accurately.

Please refer to FIG. 3, in the specific embodiment of the present application to determine the capacity consistency of the battery system based on the first open circuit voltage and the second open circuit voltage, the following steps are specifically included:

Step 301. Obtain the mapping relationship between the state of charge and the open circuit voltage.

Step 302, based on the first open circuit voltage and the mapping relationship, obtain the first state of charge of each battery cell, and based on the second open circuit voltage and the mapping relationship, obtain the The second state of charge of a battery cell.

Step 303 , based on the first capacity, the first state of charge and the second state of charge, obtain the cell capacity of each battery cell.

In the above steps, specifically, the first state of charge of the battery cell can be obtained by bringing the first open circuit voltage into the mapping relationship between the state of charge and the open circuit voltage. The second state of charge of the battery cell can be obtained by bringing the second open circuit voltage into the mapping relationship between the state of charge and the open circuit voltage. Furthermore, based on the aforementioned first capacity, the cell capacity of each battery cell can be determined.

Step 304, acquiring the preset discharge capacity and capacity consistency parameters of the battery cells of the battery system.

Step 305. Obtain the target cell capacity, wherein the target cell cell is the cell cell with the smallest cell capacity in the battery system.

Step 306: Determine a target capacity range based on the target cell capacity and the capacity consistency parameter.

Step 307, judging whether the target cell capacity is greater than or equal to the preset discharge capacity.

Step 308 , if the target cell capacity is greater than or equal to the preset discharge capacity, determine whether the cell capacity of each battery cell is within the target capacity range. In the case that the target cell capacity is less than the preset discharge capacity, it is determined that the capacity consistency of the battery system is unqualified.

Step 309 , when the cell capacity of each battery cell is within the target capacity interval, it is determined that the capacity consistency of the battery system is qualified.

In a specific embodiment, the aforementioned preset discharge capacity is a specification value during the discharge process of the battery system at a preset discharge rate. The above-mentioned capacity consistency parameters can be determined according to actual requirements, and can be specifically set within (1.01, 1.1). In addition, the target battery cell may be the battery cell with the smallest cell capacity in the battery system. The above steps determine the target capacity interval based on the target monomer capacity and capacity consistency parameters. The target capacity interval can be expressed as:

[Q _min ,A·Q _min ]

Among them, Q _min is the target monomer capacity;

A is the capacity consistency parameter.

Based on the above target capacity range and target cell capacity, the cell capacity of each battery cell is judged. First of all, the target cell capacity in the battery system needs to be greater than or equal to the target cell capacity, that is, Q ₀ ≤ Q _min , where Q ₀ is the preset discharge capacity of the battery cell. In the case of meeting the aforementioned conditions, it is judged whether the cell capacity of each battery cell is within the target capacity range, that is, whether Q _min ≤ Q _x ≤ A·Q _min is satisfied, where Q _x is any A battery cell. In the case of meeting the aforementioned conditions, it is determined that the capacity consistency of the battery system is qualified, otherwise it is unqualified.

In a specific first embodiment of the present application, the battery system may be a lithium iron phosphate battery system, and the preset discharge rate and the preset first charge rate are both The capacity consistency parameter of the lithium iron phosphate battery system is set to be 1.06C ₁ , where C ₁ is the preset first discharge rate of the lithium iron phosphate battery system. The first open circuit voltage and the second open circuit voltage of each battery cell in the lithium iron phosphate battery system are acquired. also:

Q ₀₁ ＝C ₁ ·A ₁ ·H ₁

Among them, Q ₀₁ is the preset discharge capacity of the lithium iron phosphate battery system;

A ₁ is the rated discharge current of the lithium iron phosphate battery system;

H ₁ is the actual discharge time of the lithium iron phosphate battery system.

As shown in Figure 4, line a is the total voltage of the lithium iron phosphate battery system, line b is the first open circuit voltage of the battery cell in the lithium iron phosphate battery system, and line c is the voltage of the battery cell in the lithium iron phosphate battery system second open circuit voltage. Therefore, it is determined that the target capacity interval of the lithium iron phosphate battery system is [1.02Q ₀₁ , 1.05Q ₀₁ ]. After the capacity consistency evaluation of each battery cell in the lithium iron phosphate battery system, it is determined that the capacity consistency requirements are met, and the capacity consistency of the lithium iron phosphate battery system is determined to be qualified.

In a specific second embodiment of the present application, the battery system may be a ternary polymer lithium battery system, and the ternary polymer lithium battery system is charged and discharged with a constant current. Both the preset discharge rate and the preset first charge rate can be set The capacity consistency parameter is set to 1.05·C ₂ , where C ₂ is the preset first discharge rate of the ternary polymer lithium battery system. Obtain the first open circuit voltage and the second open circuit voltage of each battery cell in the ternary polymer lithium battery system. also:

Q ₀₂ ＝C ₂ ·A ₂ ·H ₂

Among them, Q ₀₂ is the preset discharge capacity of the ternary polymer lithium battery system;

A ₂ is the rated discharge current of the ternary polymer lithium battery system;

_H2 is the actual discharge time of the ternary polymer lithium battery system.

As shown in Figure 5, the line d is the total voltage of the ternary polymer lithium battery system, the line e is the first open circuit voltage of the battery cell in the ternary polymer lithium battery system, and the line f is the ternary polymer lithium battery The second open circuit voltage of the battery cells in the system. Based on the first open circuit voltage and the second open circuit voltage, and the preset discharge capacity of the ternary polymer lithium battery system, the capacity of each cell can be determined. In the ternary polymer lithium battery system with After rate discharge, the distribution range of the cell capacity Q _X of the battery cell is [1.01Q ₀₂ , 1.04Q ₀₂ ]. Therefore, the capacity consistency of the ternary polymer lithium battery system is qualified.

Please refer to FIG. 6. FIG. 6 is a capacity consistency detection device for a battery system provided in an embodiment of the present application. As shown in FIG. 6, the capacity consistency detection device 400 includes:

The first charging module 401 is configured to charge the battery system, and recharge the battery system when the battery system is charged to the point where the open circuit voltage of the target cell meets the charging cut-off condition, wherein , the target cell is any cell in the cell system;

The second charging module 402 is configured to acquire the voltage of each battery cell in the battery system when the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition first open circuit voltage;

The discharge module 403 is configured to discharge the battery system, and obtain the first-order value of each battery cell when the battery system is discharged to the open circuit voltage of the target battery cell meeting the discharge cut-off condition. Two open circuit voltage;

A determining module 404, configured to obtain the cell capacity of each battery cell based on the first open circuit voltage and the second open circuit voltage, and based on the cell capacity of each cell cell, Capacity consistency of the battery system is determined.

Optionally, the first charging module 401 is configured to:

controlling the battery system to stand for a first period of time within a preset temperature range;

Discharging the battery system at a preset discharge rate;

When the battery system is discharged until the open circuit voltage of the target battery cell satisfies the discharge cut-off condition, controlling the battery system to stand still in a preset temperature range for a first duration;

The battery system is charged at a preset first charging rate.

Optionally, the first charging module 401 is configured to:

In the case that the open circuit voltage of the target battery cell satisfies the charging cut-off condition, controlling the battery system to stand still for a second duration, wherein the second duration is shorter than the first duration;

Secondary charging is performed on the battery system at a preset second charging rate.

Optionally, the second charging module 402 is used for:

When the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition, the battery system is controlled to stand still in a preset temperature range for a third period of time, wherein the a third duration is longer than the second duration and shorter than the first duration;

Obtain the first open-circuit voltage of each battery cell in the battery system.

The discharging module 403 is used for:

The obtaining the second open circuit voltage of each battery cell when the battery system is discharged to the open circuit voltage of the target battery cell meeting the discharge cut-off condition includes:

When the battery system is discharged until the open-circuit voltage of the target cell meets the discharge cut-off condition, controlling the battery system to stand still in the preset temperature range for the third duration;

Acquiring the second open circuit voltage of each battery cell in the battery system.

Optionally, the discharging module 403 is also used for:

Discharging the battery system, and acquiring a second open circuit voltage of each battery cell when the battery system is discharged until the open circuit voltage of the target battery cell satisfies a discharge cut-off condition.

Obtaining the first capacity of each battery cell, wherein the first capacity is a single discharge capacity of the battery system, and the cell capacity of the battery cell is determined based on the first capacity.

Optionally, the determining module 404 is configured to:

Obtain the mapping relationship between the state of charge and the open circuit voltage;

Based on the first open circuit voltage and the mapping relationship, obtain the first state of charge of each battery cell, and based on the second open circuit voltage and the mapping relationship, obtain the each battery cell the second state of charge of the monomer;

Based on the first capacity, the first state of charge and the second state of charge, the cell capacity of each battery cell is obtained.

Optionally, the determining module 404 is configured to:

Obtain the preset discharge capacity and capacity consistency parameters of the battery cells of the battery system;

Acquiring the target cell capacity of the battery cell, wherein the target cell capacity is the minimum cell capacity of the battery cell in the battery system;

determining a target capacity interval based on the target cell capacity and the capacity consistency parameter;

When the target cell capacity is greater than or equal to the preset discharge capacity, judging whether the cell capacity of each battery cell is within the target capacity range;

In a case where the cell capacity of each battery cell is within the target capacity interval, it is determined that the capacity consistency of the battery system is qualified.

The capacity consistency detection device 400 provided in the embodiment of the present invention can realize each process of a battery system capacity consistency detection method provided in the embodiment of the present invention, and can achieve the same beneficial effect. To avoid repetition, it is not repeated here repeat.

Please refer to FIG. 7 . FIG. 7 is a schematic structural diagram of a vehicle provided in an embodiment of the present application. The vehicle 500 includes: a memory 501 , a processor 502 and a computer program stored in the memory 501 and operable on the processor 502 . The embodiment of the present invention can realize each step in the embodiment of the capacity consistency detection method of the battery system as shown in FIG. 1 , and can achieve the same beneficial effect. To avoid repetition, details are not repeated here.

An embodiment of the present invention also provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the capacity of the battery system provided by the embodiment shown in FIG. 1 is realized. Each process in the consistency detection method can achieve the same technical effect, so in order to avoid repetition, details will not be repeated here. Wherein, the computer-readable storage medium is, for example, a read-only memory (Read-Only Memory, ROM for short), a random access memory (Random Access Memory, RAM for short), a magnetic disk or an optical disk, and the like.

It should be noted that, in this document, the term "comprising", "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, It also includes other elements not expressly listed, or elements inherent in the process, method, article, or device. Without further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus comprising that element.

The embodiments of the present application have been described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementations. The above-mentioned specific implementations are only illustrative and not restrictive. Those of ordinary skill in the art will Under the inspiration of this application, without departing from the purpose of this application and the scope of protection of the claims, many forms can also be made, all of which belong to the protection of this application.

Claims (10)

1. A capacity consistency detection method for a battery system, comprising: Charge the battery system, and recharge the battery system when the battery system is charged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition, wherein the target battery cell Any single cell in the cell system; Acquiring the first open circuit voltage of each battery cell in the battery system when the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition; Discharging the battery system, and obtaining the second open circuit voltage of each battery cell when the battery system is discharged until the open circuit voltage of the target battery cell meets the discharge cut-off condition; Obtaining the cell capacity of each battery cell based on the first open circuit voltage and the second open circuit voltage, and determining the cell capacity of the battery system based on the cell capacity of each cell cell Capacity Consistency. 2. The method according to claim 1, wherein the charging the battery system comprises: controlling the battery system to stand for a first period of time within a preset temperature range; Discharging the battery system at a preset discharge rate; When the battery system is discharged until the open circuit voltage of the target battery cell satisfies the discharge cut-off condition, controlling the battery system to stand still in a preset temperature range for a first duration; The battery system is charged at a preset first charging rate. 3. The method according to claim 2, characterized in that, when the battery system is charged to the point where the open-circuit voltage of the target cell meets the charging cut-off condition, the battery system is recharged, include: In the case that the open circuit voltage of the target battery cell satisfies the charging cut-off condition, controlling the battery system to stand still for a second duration, wherein the second duration is shorter than the first duration; Secondary charging is performed on the battery system at a preset second charging rate. 4. The method according to claim 3, wherein, when the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition, obtaining the battery The first open circuit voltage of each battery cell in the system, including: When the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition, the battery system is controlled to stand still in a preset temperature range for a third period of time, wherein the a third duration is longer than the second duration and shorter than the first duration; Obtaining the first open circuit voltage of each battery cell in the battery system; The obtaining the second open circuit voltage of each battery cell when the battery system is discharged to the open circuit voltage of the target battery cell meeting the discharge cut-off condition includes: When the battery system is discharged until the open-circuit voltage of the target cell meets the discharge cut-off condition, controlling the battery system to stand still in the preset temperature range for the third duration; Acquiring the second open circuit voltage of each battery cell in the battery system. 5. The method according to claim 1, characterized in that, after acquiring the second open circuit voltage of each battery cell, further comprising: Obtaining the first capacity of each battery cell, wherein the first capacity is a single discharge capacity of the battery system, and the cell capacity of the battery cell is determined based on the first capacity. 6. The method according to claim 5, wherein the obtaining the cell capacity of each battery cell based on the first open circuit voltage and the second open circuit voltage comprises: Obtain the mapping relationship between the state of charge and the open circuit voltage; Based on the first open circuit voltage and the mapping relationship, obtain the first state of charge of each battery cell, and based on the second open circuit voltage and the mapping relationship, obtain the each battery cell the second state of charge of the monomer; Based on the first capacity, the first state of charge and the second state of charge, the cell capacity of each battery cell is obtained. 7. The method according to claim 1, wherein the determining the capacity consistency of the battery system based on the capacity of each battery cell comprises: Obtain the preset discharge capacity and capacity consistency parameters of the battery cells of the battery system; Acquiring the target cell capacity of the battery cell, wherein the target cell capacity is the minimum cell capacity of the battery cell in the battery system; determining a target capacity interval based on the target cell capacity and the capacity consistency parameter; When the target cell capacity is greater than or equal to the preset discharge capacity, judging whether the cell capacity of each battery cell is within the target capacity range; In a case where the cell capacity of each battery cell is within the target capacity interval, it is determined that the capacity consistency of the battery system is qualified. 8. A capacity consistency detection device for a battery system, comprising: The first charging module is configured to charge the battery system, and recharge the battery system when the battery system is charged until the open circuit voltage of the target cell meets the charging cut-off condition, wherein, The target battery cell is any one of the battery cells in the battery system; The second charging module is configured to obtain the second charge of each battery cell in the battery system when the battery system is recharged until the open circuit voltage of the target battery cell satisfies the charging cut-off condition - open circuit voltage; The discharge module is used to discharge the battery system, and obtain the second voltage of each battery cell when the battery system is discharged to the open circuit voltage of the target battery cell meeting the discharge cut-off condition. open circuit voltage; A determining module, configured to obtain the cell capacity of each battery cell based on the first open circuit voltage and the second open circuit voltage, and determine the cell capacity based on the cell capacity of each cell cell The capacity consistency of the battery system. 9. A vehicle, characterized in that it comprises a processor and a memory, the memory stores programs or instructions that can run on the processor, and when the programs or instructions are executed by the processor, the invention according to claim 1 is realized. -The steps of the capacity consistency detection method of a battery system described in any one of 7. 10. A computer-readable storage medium, characterized in that a program or an instruction is stored on the readable storage medium, and when the program or instruction is executed by a processor, the method according to any one of claims 1-7 is implemented. A method for detecting capacity consistency of a battery system.