Capacity Consistency Detection Method, Device, Vehicle and Medium of Battery System

Abstract

The present application provides a method for detecting the capacity consistency of a battery system. The method includes: charging the battery system, and performing secondary charging on the battery system when the open-circuit voltage of the target cell module in the battery system meets the charging cut-off condition; obtaining the first open-circuit voltage of each cell module in the battery system when the battery system is secondarily charged until the open-circuit voltage of the target cell module meets the charging cut-off condition; discharging the battery system, and obtaining the second open-circuit voltage of each cell module when the open-circuit voltage of the target cell module in the battery system meets the discharging cut-off condition; obtaining the individual capacity of each cell module 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 individual capacity of each cell module.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and in particular to a method and device for detecting the capacity consistency of a battery system, a vehicle, and a medium. Background Art

[0002] 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 high energy density, good cycle performance, low self-discharge rate, and no memory effect. A battery system serving as the drive system of an electric vehicle usually consists of multiple battery cell monomers of the same model. Due to differences in the capacity, voltage, internal resistance, self-discharge rate, etc. of the battery cell monomers, especially the difference in the capacity consistency of the battery cell monomers, the discharge capacity of the battery system in which they are located often fails to reach the original level of the battery cell monomers when used in an electric vehicle, seriously affecting the range of the electric vehicle. Currently, the tests performed on a battery system are usually carried out on the overall battery system, making it difficult to evaluate the consistency differences in the capacities of all the battery cell monomers in the battery system. Summary of the Invention

[0003] Embodiments of the present application provide a method and device for detecting the capacity consistency of a battery system, a vehicle, and a medium, so as to solve the problem in the prior art that it is difficult to evaluate the consistency differences in the capacities of all the battery cell monomers in the battery system.

[0004] To solve the above technical problems, the present application is implemented as follows:

[0005] In a first aspect, an embodiment of the present application provides a method for detecting the capacity consistency of a battery system, the method including:

[0006] Charging the battery system, and when the open-circuit voltage of a target battery cell monomer in the battery system satisfies a charging cut-off condition, performing secondary charging on the battery system, where the target battery cell monomer is any one of the battery cell monomers in the battery cell system;

[0007] When the battery system is secondarily charged until the open-circuit voltage of the target battery cell monomer satisfies the charging cut-off condition, obtaining the first open-circuit voltage of each battery cell monomer in the battery system;

[0008] Discharging the battery system, and when the open-circuit voltage of the target battery cell monomer in the battery system satisfies a discharge cut-off condition, obtaining the second open-circuit voltage of each battery cell monomer;

[0009] Based on the first open-circuit voltage and the second open-circuit voltage, obtaining the monomer capacity of each battery cell monomer, and based on the monomer capacity of each battery cell monomer, determining the capacity consistency of the battery system.

[0010] Optionally, charging the battery system includes:

[0011] Controlling the battery system to stand still for a first duration within a preset temperature range;

[0012] Discharging the battery system at a preset discharge rate;

[0013] When the open-circuit voltage of the target cell in the battery system discharges to meet the discharge cut-off condition, controlling the battery system to stand still for a first duration within a preset temperature range;

[0014] Charging the battery system at a preset first charging rate.

[0015] Optionally, when the battery system is charged to the open-circuit voltage of the target cell meets the charging cut-off condition, performing a secondary charge on the battery system, including:

[0016] When the open-circuit voltage of the target cell meets the charging cut-off condition, controlling the battery system to stand still for a second duration, where the second duration is shorter than the first duration;

[0017] Performing a secondary charge on the battery system at a preset second charging rate.

[0018] Optionally, when the battery system is secondarily charged to the open-circuit voltage of the target cell meets the charging cut-off condition, obtaining the first open-circuit voltage of each cell in the battery system, including:

[0019] When the battery system is secondarily charged to the open-circuit voltage of the target cell meets the charging cut-off condition, controlling the battery system to stand still for a third duration within a preset temperature range, where the third duration is longer than the second duration and shorter than the first duration;

[0020] Obtaining the first open-circuit voltage of each cell in the battery system;

[0021] When the battery system is discharged to the open-circuit voltage of the target cell meets the discharge cut-off condition, obtaining the second open-circuit voltage of each cell, including:

[0022] When the battery system is discharged to the open-circuit voltage of the target cell meets the discharge cut-off condition, controlling the battery system to stand still for the third duration within a preset temperature range;

[0023] Obtaining the second open-circuit voltage of each cell in the battery system.

[0024] Optionally, after obtaining the second open circuit voltage of each battery cell, the method further includes:

[0025] Obtain the first capacity of each battery cell, where the first capacity is the single discharge capacity of the battery system, and the single capacity of the battery cell is determined based on the first capacity.

[0026] Optionally, the step of obtaining the single capacity of each battery cell based on the first open circuit voltage and the second open circuit voltage includes:

[0027] Obtain the mapping relationship between the state of charge and the open circuit voltage;

[0028] 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 second state of charge of each battery cell;

[0029] Based on the first capacity, the first state of charge, and the second state of charge, obtain the single capacity of each battery cell.

[0030] Optionally, the step of determining the capacity consistency of the battery system based on the single capacity of each battery cell includes:

[0031] Obtain the preset discharge capacity and the capacity consistency parameter of the battery cells of the battery system;

[0032] Obtain the target single capacity of the battery cell, where the target single capacity is the minimum single capacity of the battery cells in the battery system;

[0033] Based on the target single capacity and the capacity consistency parameter, determine the target capacity range;

[0034] In the case where the target single capacity is greater than or equal to the preset discharge capacity, determine whether the single capacity of each battery cell is within the target capacity range;

[0035] In the case where the single capacity of each battery cell is within the target capacity range, determine that the capacity consistency of the battery system is qualified.

[0036] In a second aspect, the present application further provides a device for detecting the capacity consistency of a battery system, the device includes:

[0037] A first charging module, configured to charge the battery system, and perform secondary charging on the battery system when the open circuit voltage of the target battery cell in the battery system satisfies the charging cut-off condition, where the target battery cell is any one battery cell in the battery cell system;

[0038] A second charging module, configured to obtain a first open-circuit voltage of each cell unit in the battery system when the battery system is recharged for the second time until the open-circuit voltage of the target cell unit meets the charging cut-off condition;

[0039] A discharging module, configured to discharge the battery system, and obtain a second open-circuit voltage of each cell unit when the battery system is discharged until the open-circuit voltage of the target cell unit meets the discharging cut-off condition;

[0040] A determining module, configured to obtain the capacity of each cell unit based on the first open-circuit voltage and the second open-circuit voltage, and determine the capacity consistency of the battery system based on the capacity of each cell unit.

[0041] In a third aspect, the present application further provides a vehicle, which includes a processor and a memory. The memory stores a program or instruction that can be run on the processor. When the program or instruction is executed by the processor, the steps of a method for detecting the capacity consistency of a battery system as described in any one of the first aspects are implemented.

[0042] In a fourth aspect, the present application further provides a computer-readable storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, the steps of a method for detecting the capacity consistency of a battery system as described in any one of the first aspects are implemented.

[0043] In the embodiments of the present application, by obtaining the open-circuit voltage of the battery system in the fully charged and fully discharged states, the capacity of each cell unit in the battery system can be determined. Finally, the capacity consistency of the battery system can be determined. It is possible to charge and discharge the battery system only without adding additional test items, determine whether each cell unit in the battery system meets the capacity consistency standard, and thus determine whether the capacity consistency of the battery system is qualified, which can effectively exclude cell units with poor capacity consistency. Description of the Drawings

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 is one of the flowcharts of a method for detecting the capacity consistency of a battery system provided by an embodiment of the present application;

[0046] Figure 2 It is the second flowchart of a method for detecting the capacity consistency of a battery system provided by an embodiment of the present application;

[0047] Figure 3 It is the third flowchart of a method for detecting the capacity consistency of a battery system provided by an embodiment of the present application;

[0048] Figure 4 It is the detection result of the capacity consistency of a lithium iron phosphate battery system in an embodiment of the present application;

[0049] Figure 5 It is the detection result of the capacity consistency of a lithium cobalt manganese oxide battery system in an embodiment of the present application;

[0050] Figure 6 It is the structural schematic diagram of a device for detecting the capacity consistency of a battery system provided by an embodiment of the present application;

[0051] Figure 7 It is the structural schematic diagram of a vehicle provided by an embodiment of the present application. Detailed implementation manners

[0052] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0053] An embodiment of the present application provides a method, device, vehicle and medium for detecting the capacity consistency of a battery system. Refer to Figure 1 , Figure 1 It is the first flowchart of a method for detecting the capacity consistency of a battery system provided by an embodiment of the present application. The method includes the following steps:

[0054] S101. Charge the battery system. When the open-circuit voltage of the target cell in the battery system meets the charging cut-off condition, perform secondary charging on the battery system, where the target cell is any one cell in the cell system.

[0055] In a specific implementation, the above-mentioned battery system can be a lithium-ion battery that is convenient for charging and discharging. Specifically, it can be a lithium iron phosphate battery, a ternary polymer lithium battery, etc., which can be used as a battery system for an electric vehicle power system. The present application does not limit the type of battery system used and can be selected according to actual needs. The battery system of the present application includes multiple battery cell monomers, and under the combined charging and discharging action of the multiple battery cell monomers, the vehicle is driven to travel. In addition, the above-mentioned charging cut-off condition can be a specific voltage parameter set in advance. For example, when charging the battery system, it can be determined whether the battery system is fully charged by judging whether there is an open-circuit voltage of a battery cell monomer greater than the parameter value set by the charging cut-off condition.

[0056] S102. When the battery system is recharged for the second time until the open-circuit voltage of the target battery cell monomer meets the charging cut-off condition, obtain the first open-circuit voltage of each battery cell monomer in the battery system.

[0057] In the above step, the first open-circuit voltage can be the terminal voltage of the battery cell monomer in a fully charged state and under an open-circuit condition, and the maximum state of charge of the corresponding battery cell monomer can be reflected by this first open-circuit voltage.

[0058] In a specific implementation, the battery system needs to be charged twice. After the first charge reaches the charging cut-off condition, the battery system is charged again so that there is an open-circuit voltage of a target battery cell monomer in the battery system greater than the charging cut-off condition. The two charges can prevent the battery cell monomers in the battery system from experiencing backflow or leakage due to differences in capacity, energy, power performance, service life, etc. after the first charge, and can enable the battery cell monomers in the battery system to reach a fully charged state.

[0059] S103. Discharge the battery system. When the battery system is discharged until the open-circuit voltage of the target battery cell monomer meets the discharge cut-off condition, obtain the second open-circuit voltage of each battery cell monomer.

[0060] It should be noted that the above-mentioned discharge cut-off condition can also be a voltage parameter set in advance. For example, after discharging the battery system, it can be judged whether the battery system is discharged completely by judging whether there is an open-circuit voltage of a battery cell monomer in the battery less than the voltage parameter set by the discharge cut-off condition. In addition, the second open-circuit voltage can be the terminal voltage of the battery cell monomer in a fully discharged state and under an open-circuit condition, and the minimum state of charge of the corresponding battery cell monomer can be reflected by this second open-circuit voltage.

[0061] In the above steps, after the battery system is fully charged, the battery system is discharged until the open-circuit voltage of the target cell reaches the discharge cut-off condition, that is, the battery system is fully discharged. When the battery system is fully discharged, the second open-circuit voltage of each cell is measured and obtained.

[0062] S104. Based on the first open-circuit voltage and the second open-circuit voltage, obtain the single-cell capacity of each cell, and based on the single-cell capacity of each cell, determine the capacity consistency of the battery system.

[0063] It should be understood that obtaining the single-cell capacity of a cell based on the first open-circuit voltage and the second open-circuit voltage may first determine the maximum state of charge and the minimum state of charge of the cell through the first open-circuit voltage and the second open-circuit voltage of each cell, determine the difference in the state of charge of the cell as the state-of-charge difference of the cell, and then determine the single-cell capacity of the cell by comprehensively considering the actually obtained single-cell capacity value of the cell. Specifically, it can be obtained through the following formula:

[0064]

[0065] Among them, Q X is the single-cell capacity of any one cell;

[0066] Q is the single-discharge capacity value of the cell obtained in advance;

[0067] Soc is the maximum state of charge corresponding to the first open-circuit voltage of the cell;

[0068] Soc′ is the minimum state of charge corresponding to the second open-circuit voltage of the cell.

[0069] In the above steps, based on the single-cell capacity of each cell, determining the capacity consistency of the battery system can specifically be: after determining the single-cell capacity of each cell, determine the minimum single-cell capacity among the cells in the battery system, and use this minimum single-cell capacity to determine the capacity consistency index. When the single-cell capacity of each cell is within this index, it indicates that the capacity consistency of the battery system is qualified.

[0070] In the embodiments of the present application, first, the battery system is charged until the open-circuit voltage of a single cell in the battery system reaches the charging cut-off condition, and then the battery system is charged a second time to keep the cell in a fully charged state, facilitating the determination of the first open-circuit voltage of the cell in the fully charged state. Subsequently, the battery system is discharged until the open-circuit voltage of the target cell reaches the discharge cut-off condition, and at this time, the second open-circuit voltage of the cell in the fully discharged state is determined. Based on the first open-circuit voltage and the second open-circuit voltage, the maximum capacity value and the minimum capacity value of each cell are determined, and the individual capacity of each cell is determined. Finally, the individual capacity of each cell is compared with the capacity consistency index to comprehensively determine the capacity consistency of the battery system.

[0071] The present application can obtain the individual capacity of each cell in the battery system only through the above process of charging, secondary charging, and then discharging, without adding other testing methods, so as to evaluate and determine the capacity consistency of the battery system, which can reduce the testing cost, improve the evaluation efficiency, and timely exclude the battery systems with unqualified capacity consistency.

[0072] As an alternative embodiment, the charging of the battery system includes:

[0073] Controlling the battery system to stand still for a first duration within a preset temperature range;

[0074] Discharging the battery system at a preset discharge rate;

[0075] When the open-circuit voltage of the battery system discharges to the open-circuit voltage of the target cell satisfying the discharge cut-off condition, controlling the battery system to stand still for a first duration within a preset temperature range;

[0076] Charging the battery system at a preset first charging rate.

[0077] It should be understood that controlling the battery system to stand still for a first duration within a preset temperature range enables the battery system to perform charge and discharge tests under normal conditions, preventing extreme temperatures from interfering with the battery too much and affecting the detection effect of the capacity consistency of the battery system. Discharging the battery system at a preset discharge rate enables the battery system to discharge in a constant current and stable state, reducing the interference of unstable factors on the detection of the battery system capacity. In addition, the above target cell can be any cell in the battery system. When the open-circuit voltage of the battery system discharges to the open-circuit voltage of the target cell satisfying the discharge cut-off condition, that is, the open-circuit voltage of one cell satisfies the discharge cut-off condition. In specific implementation, the battery system is discharged first and then the battery system is made to stand still, so that the battery system can remain stable after being fully discharged, facilitating subsequent charging of the battery system.

[0078] As an alternative implementation, when the open-circuit voltage of the target cell in the battery system meets the charging cut-off condition, performing secondary charging on the battery system includes:

[0079] When the open-circuit voltage of the target cell meets the charging cut-off condition, controlling the battery system to stand still for a second duration, where the second duration is shorter than the first duration;

[0080] Performing secondary charging on the battery system at a preset second charging rate.

[0081] Specifically, after the battery system is fully charged for the first time, the battery system is allowed to stand still to stabilize it. At this time, the battery system will depolarize and the voltage will decrease, and the open-circuit voltage of the cell no longer meets the charging cut-off condition. Subsequently, the battery system is charged a second time at a preset second rate smaller than the preset first charging rate, so that the open-circuit voltage of the cell in the battery system can meet the charging cut-off condition again. In this way, the battery system can be stabilized and the battery system can be stably in a fully charged state.

[0082] As an alternative implementation, when the open-circuit voltage of the target cell in the battery system during secondary charging meets the charging cut-off condition, obtaining the first open-circuit voltage of each cell in the battery system includes:

[0083] When the open-circuit voltage of the target cell in the battery system during secondary charging meets the charging cut-off condition, controlling the battery system to stand still for a third duration within a preset temperature range, where the third duration is longer than the second duration and shorter than the first duration;

[0084] Obtaining the first open-circuit voltage of each cell in the battery system;

[0085] When the battery system discharges to the open-circuit voltage of the target cell meets the discharge cut-off condition, obtaining the second open-circuit voltage of each cell includes:

[0086] When the open-circuit voltage of the target cell in the battery system discharges to meet the discharge cut-off condition, controlling the battery system to stand still for the third duration within a preset temperature range;

[0087] Obtaining the second open-circuit voltage of each cell in the battery system.

[0088] In a specific implementation, after the battery is recharged for the second time, the battery system needs to be statically placed within a preset temperature range to reduce the temperature of the battery system increased due to charging, so that the battery system tends to be stable and does not enter a discharging state. After the battery system is in a stable state, the first open-circuit voltage of each single battery cell in the battery system is measured in a timely manner. The first open-circuit voltage measured at this time can more accurately reflect the maximum charging capacity of the single battery cell. Please specifically refer to Figure 2 , in a specific embodiment of obtaining the first open-circuit voltage and the second open-circuit voltage in the present application, the following steps may be specifically included:

[0089] Step 201, control the battery system to be statically placed within a preset temperature range for a first duration.

[0090] Specifically, the first duration can be set within the range of 8 to 16 hours, and the battery system can be statically placed for 16 hours at an ambient temperature of 25°C ± 2°C.

[0091] Step 202, discharge the battery system at a preset discharge rate.

[0092] Step 203, determine whether the open-circuit voltage of the target single battery cell meets the discharge cut-off condition.

[0093] Step 204, when the battery system is discharged until the open-circuit voltage of the target single battery cell meets the discharge cut-off condition, control the battery system to be statically placed within a preset temperature range for the first duration again. When the open-circuit voltage of the target single battery cell does not meet the discharge cut-off condition, the battery system continues to discharge.

[0094] In a specific implementation, the preset discharge rate can be set within the rate range of 0.25C to 0.5C, and the battery system can be discharged at a constant current of 0.25C. When there is a single battery cell in the battery system, that is, the above-mentioned target single battery cell, discharge stops when the open-circuit voltage of the target single battery cell meets the single-cell full-window discharge cut-off condition, and the battery system is statically placed for 180 minutes. Subsequently, the battery system can be statically placed for the first duration again at an ambient temperature of 25°C ± 2°C, so that the difference between the temperature of the single battery cell and the preset ambient temperature is not higher than 2°C.

[0095] Step 205, charge the battery system at a preset first charging rate.

[0096] Step 206, determine whether the open-circuit voltage of the target single battery cell meets the charging cut-off condition.

[0097] Step 207, when the open-circuit voltage of the target battery cell monomer meets the charging cut-off condition, control the battery system to stand still for a second period of time. When the open-circuit voltage of the target battery cell monomer does not meet the charging cut-off condition, charge the battery system again at a preset first charging rate.

[0098] In the above steps, the preset first charging rate can be set within the range of 0.25C to 0.5C. The battery system can be charged at a charging rate of 0.25C. The second period of time can be set within the range of 5 seconds to 300 seconds. Subsequently, when the open-circuit voltage of the target battery cell monomer in the battery system meets the charging cut-off condition, the battery system is made to stand still for 300 seconds.

[0099] Step 208, charge the battery system for a second time at a preset second charging rate.

[0100] Step 209, judge again whether the open-circuit voltage of the target battery cell monomer meets the charging cut-off condition.

[0101] Step 210, when the battery system is charged for a second time until the open-circuit voltage of the target battery cell monomer meets the charging cut-off condition, obtain the first open-circuit voltage of each battery cell monomer in the battery system.

[0102] Specifically, after standing still, the battery system can be charged with a small current. The preset second charging rate can be set within the range of 0.01C to 0.05C. The battery system can be charged for a second time at a charging rate of 0.05C. When the battery system is charged until the open-circuit voltage of the target battery cell monomer meets the charging cut-off condition, record the first open-circuit voltage of each battery cell monomer.

[0103] Step 211, discharge the battery system for a second time at a preset discharge rate.

[0104] Step 212, judge whether the open-circuit voltage of the target battery cell monomer meets the discharge cut-off condition.

[0105] Step 213, when the battery system is discharged for a second time until the open-circuit voltage of the target battery cell monomer meets 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 monomer. When the battery system is discharged for a second time until the open-circuit voltage of the target battery cell monomer does not meet the discharge cut-off condition, continue to discharge the battery system for a second time.

[0106] In the specific implementation steps, before the secondary discharge of the battery system, the battery system can be placed in an environment temperature of 25°C ± 2°C and left to stand for a first period of time, and it is required that the temperature difference between the battery system and the environment 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 cell meets the single-cell full-window discharge cut-off condition. In addition, the third period of time can be set within the range of 30 minutes to 180 minutes. When the open-circuit voltage of the target cell meets the discharge cut-off condition, after the battery system is left to stand for the third period of time, record the second open-circuit voltage of each cell.

[0107] Continue to refer to Figure 2 ., through the processes of discharging, charging, secondary charging, and secondary discharging the battery system in the above steps, obtain the first open-circuit voltage representing the maximum state of charge and the second open-circuit voltage representing the minimum state of charge for each cell in the battery system.

[0108] As an alternative implementation, after obtaining the second open-circuit voltage of each cell, it further includes:

[0109] Obtain the first capacity of each cell, where the first capacity is the single discharge capacity of the battery system, and the single-cell capacity of the cell is determined based on the first capacity.

[0110] It is worth mentioning that the first capacity in this application can be the single discharge capacity of the battery system. The single-cell capacity of the cell can be obtained through the first capacity, the first open-circuit voltage, and the second open-circuit voltage. The specific calculation formula has been described above and will not be elaborated here.

[0111] As an alternative implementation, obtaining the single-cell capacity of each cell based on the first open-circuit voltage and the second open-circuit voltage includes:

[0112] Obtain the mapping relationship between the state of charge and the open-circuit voltage;

[0113] Based on the first open-circuit voltage and the mapping relationship, obtain the first state of charge of each cell, and based on the second open-circuit voltage and the mapping relationship, obtain the second state of charge of each cell;

[0114] Based on the first capacity, the first state of charge, and the second state of charge, obtain the single-cell capacity of each cell.

[0115] In specific implementation, the mapping relationship between the state of charge and the open-circuit voltage can be possessed by a single battery cell, and can be represented as a corresponding table of the mapping relationship between the state of charge and the open-circuit voltage. Through this mapping relationship, the state of charge can be determined based on the open-circuit voltage, that is, the actual displayed capacity of the single battery cell. The above first state of charge can be the maximum state of charge corresponding to the first open-circuit voltage, and the second state of charge can be the minimum state of charge corresponding to the second open-circuit voltage. Then, through the difference between the first state of charge and the second state of charge, and the first capacity, the single-cell capacity of each single battery cell is obtained. Specifically, the following formula can be referred to:

[0116]

[0117] Wherein, Q X is the single-cell capacity of any single battery cell;

[0118] Q is the first capacity, that is, the single discharge capacity value of the battery system;

[0119] Soc x is the first state of charge;

[0120] Soc′ x is the second state of charge.

[0121] As an optional implementation manner, determining the capacity consistency of the battery system based on the single-cell capacity of each single battery cell includes:

[0122] Obtaining the preset discharge capacity and capacity consistency parameter of the single battery cells of the battery system;

[0123] Obtaining the target single-cell capacity, wherein the target single-cell capacity is the minimum single-cell capacity possessed by the single battery cells in the battery system;

[0124] Based on the target single-cell capacity and the capacity consistency parameter, determining a target capacity range;

[0125] When the target single-cell capacity is greater than or equal to the preset discharge capacity, judging whether the single-cell capacity of each single battery cell is within the target capacity range;

[0126] When the single-cell capacity of each single battery cell is within the target capacity range, determining that the capacity consistency of the battery system is qualified.

[0127] In the above embodiment, a target capacity range is determined based on the preset discharge capacity of the battery system and the capacity consistency parameter determined according to the actual test requirements. This target capacity range can be used as an indicator to measure whether the capacity of each single battery cell meets the capacity consistency standard, and can accurately determine whether the single battery cells in the battery system are qualified, facilitating the timely exclusion of single battery cells that do not meet the capacity consistency standard, and also reducing the detection cost of capacity consistency.

[0128] In addition, the above-obtained target single-cell capacity is the minimum single-cell capacity of the single battery cells in the battery system. The target single-cell capacity can be the minimum difference between the first open-circuit voltage and the second open-circuit voltage of the single battery cell, or the minimum charge-discharge capacity value of the single battery cells in the battery system. By judging whether the capacity of the battery system meets the preset discharge capacity and using this as the first standard to measure whether the capacity consistency of the battery system is qualified, the capacity consistency detection result can be determined more accurately.

[0129] Please refer to Figure 3 , in a specific embodiment of the present application for determining 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:

[0130] Step 301, obtain the mapping relationship between the state of charge and the open-circuit voltage.

[0131] Step 302, based on the first open-circuit voltage and the mapping relationship, obtain the first state of charge of each single battery cell, and based on the second open-circuit voltage and the mapping relationship, obtain the second state of charge of each single battery cell.

[0132] Step 303, based on the first capacity, the first state of charge, and the second state of charge, obtain the single-cell capacity of each single battery cell.

[0133] In the above steps, specifically, the first state of charge of the single battery cell can be obtained by substituting 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 single battery cell can be obtained by substituting the second open-circuit voltage into the mapping relationship between the state of charge and the open-circuit voltage. Then, based on the aforementioned first capacity, the single-cell capacity of each single battery cell can be determined.

[0134] Step 304, obtain the preset discharge capacity and the capacity consistency parameter of the single battery cells of the battery system.

[0135] Step 305, obtain the target single-cell capacity, where the target single battery cell is the single battery cell with the minimum single-cell capacity in the battery system.

[0136] Step 306: Determine the target capacity range based on the target single-cell capacity and the capacity consistency parameter.

[0137] Step 307: Determine whether the target single-cell capacity is greater than or equal to the preset discharge capacity.

[0138] Step 308: When the target single-cell capacity is greater than or equal to the preset discharge capacity, determine whether the single-cell capacity of each battery cell is within the target capacity range. When the target single-cell capacity is less than the preset discharge capacity, it is determined that the capacity consistency of the battery system is unqualified.

[0139] Step 309: When the single-cell capacity of each battery cell is within the target capacity range, it is determined that the capacity consistency of the battery system is qualified.

[0140] In a specific embodiment, the above preset discharge capacity is the specification value during the discharge process of the battery system at a preset discharge rate. The above capacity consistency parameter can be specifically determined according to actual requirements, and can be specifically set within (1.01, 1.1). In addition, the target battery cell can be the battery cell with the smallest single-cell capacity in the battery system. The above steps determine the target capacity range based on the target single-cell capacity and the capacity consistency parameter. The target capacity range can be expressed as:

[0141] [Q min , A·Q min

[0142] Among them, Q min is the target single-cell capacity;

[0143] A is the capacity consistency parameter.

[0144] Based on the above target capacity range and target single-cell capacity, the single-cell capacity of each battery cell is judged. First, it is required that the target single-cell capacity in the battery system is greater than or equal to the target single-cell capacity, that is, Q 0 ≤Q min , where Q 0 is the preset discharge capacity of the battery cell. When the above conditions are met, it is judged whether the single-cell capacity of each battery cell is within the target capacity range, that is, whether Q min ≤Q x ≤A·Q min , where Q x is any battery cell in the battery system. When the above conditions are met, it is determined that the capacity consistency of the battery system is qualified, otherwise it is unqualified.

[0145] In a specific first embodiment of the present application, the battery system can be a lithium iron phosphate battery system. It is set that the preset discharge rate and the preset first charge rate are both Set the capacity consistency parameter of the lithium iron phosphate battery system to 1.06C 1 , where C 1 is the preset first discharge rate of the lithium iron phosphate battery system. Obtain the first open-circuit voltage and the second open-circuit voltage of each single cell in the lithium iron phosphate battery system. In addition:

[0146] Q 01 = C 1 ·A 1 ·H 1

[0147] where Q 01 is the preset discharge capacity of the lithium iron phosphate battery system;

[0148] A 1 is the rated discharge current of the lithium iron phosphate battery system;

[0149] H 1 is the actual discharge time of the lithium iron phosphate battery system.

[0150] As Figure 4 shown, line a is the total voltage of the lithium iron phosphate battery system, line b is the first open-circuit voltage of the single cells in the lithium iron phosphate battery system, and line c is the second open-circuit voltage of the single cells in the lithium iron phosphate battery system. Thus, determine the target capacity range of the lithium iron phosphate battery system to be [1.02Q 01 , 1.05Q 01 . After evaluating the capacity consistency of each single cell in the lithium iron phosphate battery system, it is determined that the capacity consistency requirement is met, and the capacity consistency of the lithium iron phosphate battery system is determined to be qualified.

[0151] In a specific second embodiment of the present application, the battery system can be a ternary polymer lithium battery system, and constant current charge and discharge are performed on the ternary polymer lithium battery system. The preset discharge rate and the preset first charge rate can be set to both Set the capacity consistency parameter 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 single cell in the ternary polymer lithium battery system. In addition:

[0152] Q 02 = C 2 ·A 2 ·H 2

[0153] where Q 02 is the preset discharge capacity of the ternary polymer lithium battery system;

[0154] A 2 is the rated discharge current of the ternary polymer lithium battery system;

[0155] H 2 is the actual discharge time of the ternary polymer lithium battery system.

[0156] As Figure 5 shown, line d is the total voltage of the ternary polymer lithium battery system, line e is the first open-circuit voltage of the single battery cell in the ternary polymer lithium battery system, and line f is the second open-circuit voltage of the single battery cell in the ternary polymer lithium battery system. Based on the first open-circuit voltage, the second open-circuit voltage, and the preset discharge capacity of the ternary polymer lithium battery system, the single-cell capacity of each single battery cell can be determined. After discharging at rate in the ternary polymer lithium battery system, the distribution range of the single-cell capacity Q X of the single battery cell is [1.01Q 02 , 1.04Q 02 . Therefore, the capacity consistency of the ternary polymer lithium battery system is qualified.

[0157] Please refer to Figure 6 , Figure 6 which is a device for detecting the capacity consistency of a battery system provided by an embodiment of the present application. As Figure 6 shown, the capacity consistency detection device 400 includes:

[0158] A first charging module 401, configured to charge the battery system, and perform secondary charging on the battery system when the open-circuit voltage of the target single battery cell in the battery system satisfies the charging cut-off condition, where the target single battery cell is any single battery cell in the battery cell system;

[0159] A second charging module 402, configured to obtain the first open-circuit voltage of each single battery cell in the battery system when the battery system is charged to the open-circuit voltage of the target single battery cell satisfying the charging cut-off condition;

[0160] A discharge module 403, configured to discharge the battery system, and obtain the second open-circuit voltage of each single battery cell when the battery system is discharged to the open-circuit voltage of the target single battery cell satisfying the discharge cut-off condition;

[0161] A determination module 404, configured to obtain the single-cell capacity of each single battery cell based on the first open-circuit voltage and the second open-circuit voltage, and determine the capacity consistency of the battery system based on the single-cell capacity of each single battery cell.

[0162] Optionally, the first charging module 401 is configured to:

[0163] Control the battery system to stand still for a first period of time within a preset temperature range;

[0164] Discharge the battery system at a preset discharge rate;

[0165] When the open-circuit voltage of the target cell in the battery system satisfies the discharge cut-off condition, control the battery system to stand still for a first period of time within a preset temperature range;

[0166] Charge the battery system at a preset first charging rate.

[0167] Optionally, the first charging module 401 is used for:

[0168] When the open-circuit voltage of the target cell satisfies the charging cut-off condition, control the battery system to stand still for a second period of time, where the second period of time is shorter than the first period of time;

[0169] Recharge the battery system at a preset second charging rate.

[0170] Optionally, the second charging module 402 is used for:

[0171] When the battery system is recharged until the open-circuit voltage of the target cell satisfies the charging cut-off condition, control the battery system to stand still for a third period of time within a preset temperature range, where the third period of time is longer than the second period of time and shorter than the first period of time;

[0172] Obtain the first open-circuit voltage of each cell in the battery system.

[0173] The discharge module 403 is used for:

[0174] When the battery system is discharged until the open-circuit voltage of the target cell satisfies the discharge cut-off condition, obtaining the second open-circuit voltage of each cell includes:

[0175] When the battery system is discharged until the open-circuit voltage of the target cell satisfies the discharge cut-off condition, control the battery system to stand still for the third period of time within a preset temperature range;

[0176] Obtain the second open-circuit voltage of each cell in the battery system.

[0177] Optionally, the discharge module 403 is further used for:

[0178] Discharge the battery system. When the open circuit voltage of the target battery cell reaches the discharge cut-off condition during the discharge of the battery system, obtain the second open circuit voltage of each battery cell.

[0179] Obtain the first capacity of each battery cell, where the first capacity is the single-discharge capacity of the battery system, and the single-cell capacity of the battery cell is determined based on the first capacity.

[0180] Optionally, the determining module 404 is configured to:

[0181] Obtain the mapping relationship between the state of charge and the open circuit voltage;

[0182] 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 second state of charge of each battery cell;

[0183] Based on the first capacity, the first state of charge, and the second state of charge, obtain the single-cell capacity of each battery cell.

[0184] Optionally, the determining module 404 is configured to:

[0185] Obtain the preset discharge capacity and the capacity consistency parameter of the battery cells of the battery system;

[0186] Obtain the target single-cell capacity, where the target single-cell capacity is the minimum single-cell capacity of the battery cells in the battery system;

[0187] Based on the target single-cell capacity and the capacity consistency parameter, determine the target capacity range;

[0188] When the target single-cell capacity is greater than or equal to the preset discharge capacity, determine whether the single-cell capacity of each battery cell is within the target capacity range;

[0189] When the single-cell capacity of each battery cell is within the target capacity range, determine that the capacity consistency of the battery system is qualified.

[0190] The capacity consistency detection device 400 provided in the embodiments of the present invention can implement each process of a method for detecting the capacity consistency of a battery system provided in the embodiments of the present invention, and can achieve the same beneficial effects. To avoid repetition, details are not described herein again.

[0191] Please refer to Figure 7 , Figure 7It is a schematic structural diagram of a vehicle provided by an embodiment of the present application. The vehicle 500 includes: a memory 501, a processor 502, and a computer program stored on the memory 501 and executable on the processor 502. Embodiments of the present invention can implement each step in the embodiment of the capacity consistency detection method of the battery system as shown in Figure 1 and can achieve the same beneficial effects. To avoid repetition, they will not be described here again.

[0192] Embodiments of the present invention further provide a computer-readable storage medium. A computer program is stored on the computer-readable storage medium. When the computer program is executed by the processor, it implements each process in the capacity consistency detection method of the battery system provided by the embodiment as shown in Figure 1 and can achieve the same technical effects. To avoid repetition, they will not be described here again. Among them, the computer-readable storage medium includes, for example, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disc.

[0193] It should be noted that in this article, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without more limitations, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the element.

[0194] The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all of them fall within the protection scope of the present application.

Claims

1. A method for detecting the capacity consistency of a battery system, characterized in that, it includes: Charging the battery system, and when the open-circuit voltage of the target cell in the battery system meets the charging cut-off condition, performing secondary charging on the battery system, where the target cell is any one cell in the battery system; When the battery system is secondarily charged until the open-circuit voltage of the target cell meets the charging cut-off condition, obtaining the first open-circuit voltage of each cell in the battery system; Discharging the battery system, and when the open-circuit voltage of the target cell in the battery system meets the discharge cut-off condition, obtaining the second open-circuit voltage of each cell; Based on the first open-circuit voltage and the second open-circuit voltage, obtaining the individual capacity of each cell, and based on the individual capacity of each cell, determining the capacity consistency of the battery system; Wherein, the performing secondary charging on the battery system when the open-circuit voltage of the target cell in the battery system meets the charging cut-off condition includes: When the open-circuit voltage of the target cell meets the charging cut-off condition, controlling the battery system to stand still for a second duration; Performing secondary charging on the battery system at a preset second charging rate; Wherein, the obtaining the individual capacity of each cell based on the first open-circuit voltage and the second open-circuit voltage includes: Obtaining the mapping relationship between the state of charge and the open-circuit voltage; Based on the first open-circuit voltage and the mapping relationship, obtaining the first state of charge of each cell, and based on the second open-circuit voltage and the mapping relationship, obtaining the second state of charge of each cell; Based on the first capacity, the first state of charge and the second state of charge, obtaining the individual capacity of each cell; Wherein, the determining the capacity consistency of the battery system based on the individual capacity of each cell includes: Obtaining the preset discharge capacity and the capacity consistency parameter of the cells in the battery system; Obtaining the target individual capacity of the cell, where the target individual capacity is the minimum individual capacity of the cells in the battery system; Based on the target individual capacity and the capacity consistency parameter, determining the target capacity range; When the target individual capacity is greater than or equal to the preset discharge capacity, determining whether the individual capacity of each cell is within the target capacity range; When the individual capacity of each cell is within the target capacity range, determining that the capacity consistency of the battery system is qualified.

2. The method according to claim 1, characterized in that, the charging the battery system includes: Controlling the battery system to stand still for a first duration within a preset temperature range, and the first duration is longer than the second duration; Discharging the battery system at a preset discharge rate; When the battery system discharges until the open-circuit voltage of the target cell meets the discharge cut-off condition, control the battery system to stand still for a first period within a preset temperature range; Charge the battery system at a preset first charging rate.

3. The method according to claim 2, wherein, when the battery system is recharged until the open-circuit voltage of the target cell meets the charge cut-off condition, obtaining the first open-circuit voltage of each cell in the battery system includes: when the battery system is recharged until the open-circuit voltage of the target cell meets the charge cut-off condition, control the battery system to stand still for a third period within a preset temperature range, wherein the third period is longer than the second period and shorter than the first period; obtain the first open-circuit voltage of each cell in the battery system; when the battery system discharges until the open-circuit voltage of the target cell meets the discharge cut-off condition, obtaining the second open-circuit voltage of each cell includes: when the battery system discharges until the open-circuit voltage of the target cell meets the discharge cut-off condition, control the battery system to stand still for the third period within a preset temperature range; obtain the second open-circuit voltage of each cell in the battery system.

4. The method according to claim 1, wherein, after obtaining the second open-circuit voltage of each cell, further includes: obtaining the first capacity of each cell, wherein the first capacity is the single discharge capacity of the battery system, and the single cell capacity of the cell is determined based on the first capacity.

5. A capacity consistency detection device for a battery system, wherein, includes: A first charging module for charging the battery system, and when the open-circuit voltage of the target cell in the battery system meets the charge cut-off condition, recharging the battery system, wherein the target cell is any one cell in the battery system; A second charging module for obtaining the first open-circuit voltage of each cell in the battery system when the battery system is recharged until the open-circuit voltage of the target cell meets the charge cut-off condition; A discharge module for discharging the battery system, and obtaining the second open-circuit voltage of each cell when the battery system discharges until the open-circuit voltage of the target cell meets the discharge cut-off condition; A determination module for obtaining the single cell capacity of each cell 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 single cell capacity of each cell; wherein, the first charging module is used for: when the open-circuit voltage of the target cell meets the charge cut-off condition, control the battery system to stand still for a second period; recharge the battery system at a preset second charging rate; wherein, the determination module is used for: 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 second state of charge of each battery cell; Based on the first capacity, the first state of charge and the second state of charge, obtain the cell capacity of each battery cell; The determining module is configured to: Obtain the preset discharge capacity and the capacity consistency parameter of the battery cells of the battery system; Obtain the target cell capacity, where the target cell capacity is the minimum cell capacity of the battery cells in the battery system; Based on the target cell capacity and the capacity consistency parameter, determine the target capacity range; When 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; When the cell capacity of each battery cell is within the target capacity range, determine that the capacity consistency of the battery system is qualified.

6. A vehicle, characterized in that, It includes a processor and a memory, and the memory stores a program or instruction that can run on the processor. When the program or instruction is executed by the processor, the steps of a method for detecting the capacity consistency of a battery system as described in any one of claims 1-4 are implemented.

7. A computer-readable storage medium, characterized in that, The readable storage medium stores a program or instruction. When the program or instruction is executed by a processor, the steps of a method for detecting the capacity consistency of a battery system as described in any one of claims 1-4 are implemented.

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