Method, system and device for improving battery open-circuit voltage test precision and medium

Abstract

The invention relates to a method, system, equipment and medium for improving battery open-circuit voltage test precision, and belongs to the technical field of battery test.The method for improving the battery open-circuit voltage test precision comprises the following steps that a battery in a fresh state is obtained for constant volume test, and the capacity of the battery is determined; in a set constant temperature environment, the SOC state of the battery is adjusted based on the capacity of the constant volume test, and it is ensured that the constant temperature of the battery is recovered to the set constant temperature before each adjustment; for each set SOC state of the battery, OCV values are measured under different set temperature conditions, and SOC-OCV data under different temperature conditions are obtained. According to the method, the SOC-OCV data under different temperature conditions are accurately obtained, reliable basic data support is provided for SOC correction and SOH calculation of the battery management system, and the accuracy of battery state evaluation is remarkably improved.

Description

Technical Field

[0001] The present disclosure belongs to the field of battery testing technology, and in particular relates to a method, system, device, and medium for improving the accuracy of battery open circuit voltage testing. Background Art

[0002] Currently, in the development of battery management systems, open-circuit voltage (OCV) curves are commonly used to correct battery state-of-charge (SOC) and calculate state-of-health (SOH). However, the OCV curve is susceptible to drift, which reduces the accuracy of SOC correction and SOH calculation. Traditional testing methods require long OCV curve tests at different temperatures and SOC states. This is not only time-consuming but also increases the risk of errors due to self-discharge or capacity fade.

[0003] Therefore, it is necessary to provide a new method, system, device and medium for improving the accuracy of battery open circuit voltage testing to solve the above technical problems. Summary of the Invention

[0004] The purpose of the present disclosure is to provide a method, system, device and medium for improving the accuracy of battery open circuit voltage testing in order to solve the above problems.

[0005] The present disclosure achieves the above objectives through the following technical solutions: A method for improving the accuracy of battery open circuit voltage testing comprises the following steps: Obtain fresh batteries for constant capacity testing to determine the battery capacity; Under a set constant temperature environment, adjust the battery's SOC based on the capacity of the constant capacity test, and ensure that the battery returns to the set constant temperature before each adjustment; For each set SOC state of the battery, the OCV value is measured under different set temperature conditions to obtain SOC-OCV data under different temperature conditions.

[0006] As a further optimization solution of the present disclosure, a constant capacity test is performed using a current with a charge and discharge rate less than a preset rate.

[0007] As a further optimization solution of the present disclosure, when the cumulative test time is greater than a preset duration or the number of test cycles is greater than a preset number, the constant volume test needs to be performed again.

[0008] As a further optimization scheme of the present disclosure, the capacity cut-off method is used to adjust the SOC state of the battery; before each adjustment of the SOC state of the battery, the battery is placed in a set constant temperature environment for a corresponding preset time according to different temperature test conditions until it reaches a thermal equilibrium state.

[0009] As a further optimization solution of the present disclosure, for each set SOC state of the battery, the OCV value is measured under different set temperature conditions, including: For each set SOC state of the battery, OCV values ​​are measured under different temperature conditions. Different SOC states of the battery include but are not limited to the following 35 key SOC states: 100%, 99%, 98%, 95%, 85%, 75%, 65%, 63%, 61%, 59%, 57%, 55%, 45%, 35%, 30%, 28%, 26%, 24%, 22%, 20%, 18%, 16%, 14%, 12%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, and 0%.

[0010] As a further optimization solution of the present disclosure, it also includes: Based on the SOC-OCV correspondence data under different temperature conditions, a complete battery characteristic curve is established.

[0011] A system for improving the accuracy of battery open circuit voltage testing, comprising: The capacity determination module is used to obtain fresh batteries for capacity determination testing to determine the battery capacity; The SOC state adjustment module is used to adjust the battery's SOC state based on the capacity of the constant capacity test under a set constant temperature environment, and ensure that the battery returns to the set constant temperature before each adjustment; The measurement module is used to measure the OCV value under different set temperature conditions for each set SOC state of the battery, and obtain SOC-OCV data under different temperature conditions.

[0012] The SOC state adjustment module uses a capacity cutoff method to adjust the SOC state of the battery; before each adjustment of the SOC state of the battery, the battery is placed in a set constant temperature environment for a corresponding preset time according to different temperature test conditions until it reaches a thermal equilibrium state.

[0013] An electronic device, comprising a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus; Memory for storing computer programs; The processor is used to execute the program stored in the memory to implement the method for improving the accuracy of battery open circuit voltage testing.

[0014] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the method for improving the accuracy of battery open circuit voltage testing.

[0015] The beneficial effects of the present disclosure are: The present disclosure provides reliable basic data support for SOC correction and SOH calculation of the battery management system by accurately obtaining SOC-OCV data under different temperature conditions, significantly improving the accuracy of battery state assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a flowchart of the method in an embodiment of the present disclosure; Figure 2 is a specific flowchart of the method in an embodiment of the present disclosure; Figure 3 is a block diagram of the system structure in an embodiment of the present disclosure; Figure 4 is a block diagram of the device structure in an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The following further describes the present application in detail with reference to the accompanying drawings. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0018] As Figure 1 shown, a method for improving the accuracy of battery open-circuit voltage testing includes the following steps: S1. Obtain the capacity of the battery through constant-volume testing of the battery in a fresh state (only after the initial process and without actual use), including: Cell pre-treatment and constant-volume testing require obtaining the fresh-state cell and performing constant-volume testing using a low-rate current with a charge-discharge rate less than 0.5C to eliminate the influence of cell polarization and determine the actual capacity of the cell, providing an accurate data basis for subsequent SOC state adjustment.

[0019] S2. Under a set constant-temperature environment, adjust the SOC state of the battery based on the capacity obtained from the constant-volume testing, and ensure that the battery returns to the set constant temperature before each adjustment, including: The SOC adjustment requires adjusting the SOC state of the battery using the capacity cut-off method based on the constant-volume testing results in a 25°C constant-temperature environment. Before each SOC state adjustment, the battery needs to be left at 25°C until it reaches thermal equilibrium to ensure that it returns to 25°C before each adjustment. Before adjusting the SOC state using the capacity cut-off, the requirements are: For low-temperature test conditions (≤0°C), it needs to be left at 25°C for >8 hours; For high-temperature test conditions (>25°C), it needs to be left at 25°C for >4 hours; For normal-temperature test conditions (0°C < Ttest < 25°C), it needs to be left at 25°C for >6 hours.

[0020] The constant volume capacity needs to be calibrated during the test. When the cumulative experimental time is greater than 72 hours or the number of test cycles is greater than 3 times, the capacity needs to be recalibrated to ensure that the test accuracy meets the requirements.

[0021] S3. For each set state of battery SOC, measure the OCV value under different set temperature conditions to obtain SOC-OCV data under different temperature conditions, including: For each set SOC state, OCV value measurement is performed under corresponding temperature conditions. According to the voltage platform characteristics of lithium iron phosphate batteries, SOC test points are reasonably set, including but not limited to the following 35 key SOC states: 100%, 99%, 98%, 95%, 85%, 75%, 65%, 63%, 61%, 59%, 57%, 55%, 45%, 35%, 30%, 28%, 26%, 24%, 22%, 20%, 18%, 16%, 14%, 12%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0%.

[0022] Output SOC-OCV correspondence data under different temperature conditions to establish a complete battery characteristic curve, providing an accurate reference for SOC estimation of the battery management system (BMS).

[0023] In this embodiment, it specifically includes: The following are explanations of several key terms involved: ① In this test specification, for all lithium iron phosphate cells (square and cylindrical cells), the charge and discharge test voltage range is 2.5 (2.0) ~ 3.65V (T>0℃, discharge to 2.5V; T≤0℃, discharge to 2.0V) or the voltage range specified by the R&D personnel; ②Vmin: discharge cut-off voltage, 2.5V (T>0℃), 2.0V (T≤0℃); ③Vmax: charging cut-off voltage, 3.65V; ④C0: Test battery fixed capacity; ⑤X%SOC: Target SOC state of the measured OCV, X interval range is [0,100].

[0024] like Figure 2 As shown, the following are the specific implementation steps of this method: 1. Test the capacity of the battery cell at 25 degrees: ① Under a 25°C environment, connect all fresh single batteries to the test cabinet according to their positive and negative terminals and let them stand for 30 minutes; ②Discharge at 1 / 3C constant current to Vmin, let it stand for 30 minutes; charge at 1 / 3C constant current to Vmax, constant voltage cutoff current 0.05C, let it stand for 30 minutes; repeat this charge and discharge test method three times, and record the third discharge capacity C0.

[0025] 2. Adjust the battery SOC status at 25 degrees: ①100% SOC adjustment: At 25°C, charge the above-mentioned fixed-capacity battery cell at 1 / 3C constant current to Vmax (or the standard charging current specified by the R&D personnel), with a constant voltage cutoff current of 0.05C, and leave it for 1 hour; ②99% SOC adjustment: a. Place the cells tested at different temperatures (not 25 degrees) at 25 degrees Celsius for a certain period of time to reach thermal equilibrium (high temperature shelf time > 4 hours, low temperature shelf time > 6 / 8 hours); b. 1 / 3C constant current discharge to Vmin, and let it stand for 30 minutes; c. Charge to Vmax with a constant current of 1 / 3C, set the cut-off current to 0.05C, and let it stand for 30 minutes; d. 1 / 3C constant current discharge 1% SOC (i.e. 1% C0), let it stand for 30 minutes; ③Other SOC status adjustments: a. Place the cells tested under different temperature conditions at 25°C for more than 6 hours to reach thermal equilibrium; b. 1 / 3C constant current discharge to Vmin, and let it stand for 30 minutes; c. Charge to Vmax with a constant current of 1 / 3C, set the cut-off current to 0.05C, and let it stand for 30 minutes; d. 1 / 3C constant current discharge (100%-X%) SOC (i.e. (100%-X%) C0, current step X% corresponds to 2% SOC→100% SOC), and let it stand for 30 minutes; When testing under the same temperature conditions, the two batteries under test are required to be adjusted from a high SOC state to a low SOC state in sequence, 100% SOC → 0% SOC; if the cumulative test time is ≥ 3 days from the last capacity calibration time, the battery capacity must be re-calibrated, and the SOC state of the battery to be tested shall be adjusted according to the latest calibrated capacity.

[0026] 3. OCV test under different temperature conditions: ① Connect the two batteries after SOC adjustment to the test cabinet according to the positive and negative terminals, and place them at the test temperature (25℃ / +45℃ / +10℃ / 0℃ / -10℃ / -20℃ / -30℃) for 10 hours to ensure that the batteries reach thermal equilibrium at the test temperature before testing; ②After the test conditions are met, conduct OCV test and record; 4. Output SOC-OCV data under different temperature conditions.

[0027] like Figure 3 As shown, an embodiment of the present disclosure provides a system for improving the accuracy of battery open circuit voltage testing, including: The capacity determination module is used to obtain fresh batteries for capacity determination testing to determine the battery capacity; The SOC state adjustment module is used to adjust the battery's SOC state based on the capacity of the constant capacity test under a set constant temperature environment, and ensure that the battery returns to the set constant temperature before each adjustment; The measurement module is used to measure the OCV value under different set temperature conditions for each set SOC state of the battery, and obtain SOC-OCV data under different temperature conditions.

[0028] The implementation process of the functions and effects of each module in the above system is specifically described in the implementation process of the corresponding steps in the above method, which will not be repeated here.

[0029] For the system embodiment, since it basically corresponds to the method embodiment, the relevant parts can be referred to the partial description of the method embodiment. The system embodiment described above is only schematic, wherein the modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they may be located in one place, or they may be distributed on multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the disclosed solution. Those of ordinary skill in the art can understand and implement it without paying any creative work.

[0030] In the above embodiments, any number of all modules can be combined into one module for implementation, or any one of the modules can be split into multiple modules. Alternatively, at least part of the functionality of one or more of these modules can be combined with at least part of the functionality of other modules and implemented in one module. At least one of all modules can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application-specific integrated circuit (ASIC), or can be implemented in hardware or firmware by any other reasonable means of integrating or packaging the circuit, or can be implemented in any one of the three implementation methods of software, hardware, and firmware, or in an appropriate combination of any of them. Alternatively, at least one of all modules can be at least partially implemented as a computer program module, which can perform the corresponding function when the computer program module is executed.

[0031] See also Figure 3The electronic device provided by an embodiment of the present disclosure includes a processor 1110, a communication interface 1120, a memory 1130 and a communication bus 1140, wherein the processor 1110, the communication interface 1120, and the memory 1130 communicate with each other through the communication bus 1140; Memory 1130, for storing computer programs; The processor 1110 is configured to implement the above-mentioned method for improving the accuracy of battery open circuit voltage testing when executing the program stored in the memory 1130 . The communication bus 1140 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The communication bus 1140 can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, the figure shows only one thick line, but this does not mean that there is only one bus or only one type of bus.

[0032] The communication interface 1120 is used for communication between the electronic device and other devices.

[0033] The memory 1130 may include a random access memory (RAM) or a non-volatile memory, such as at least one disk storage. Alternatively, the memory 1130 may be at least one storage device located away from the processor 1110.

[0034] The above-mentioned processor 1110 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0035] The embodiments of the present disclosure further provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for improving the accuracy of battery open circuit voltage testing as described above.

[0036] The computer-readable storage medium may be included in the device / apparatus described in the above embodiments, or may exist independently and not incorporated into the device / apparatus. The computer-readable storage medium carries one or more programs that, when executed, implement the method for improving the accuracy of battery open-circuit voltage testing according to the embodiments of the present disclosure.

[0037] According to embodiments of the present disclosure, a computer-readable storage medium may be a non-volatile computer-readable storage medium, such as, but not limited to, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present disclosure, a computer-readable storage medium may be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0038] The above-described embodiments merely represent several implementation methods of the present disclosure. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present disclosure. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the scope of the present disclosure, all of which fall within the scope of protection of the present disclosure.

Claims

1. A method for improving the accuracy of battery open circuit voltage testing, characterized in that: The following steps are involved: Obtain fresh batteries for constant capacity testing to determine the battery capacity; Under a set constant temperature environment, adjust the battery's SOC based on the capacity of the constant capacity test, and ensure that the battery returns to the set constant temperature before each adjustment; For each set SOC state of the battery, the OCV value is measured under different set temperature conditions to obtain SOC-OCV data under different temperature conditions.

2. A method for improving the accuracy of battery open circuit voltage testing according to claim 1, characterized in that: Perform constant capacity test using a current with a charge / discharge rate lower than the preset rate.

3. The method for improving the accuracy of battery open circuit voltage testing according to claim 1, wherein: When the cumulative test time is greater than the preset time or the number of test cycles is greater than the preset number, the constant volume test needs to be repeated.

4. The method for improving the accuracy of battery open circuit voltage testing according to claim 1, wherein: The capacity cut-off method is used to adjust the battery's SOC state. Before each adjustment of the battery's SOC state, the battery is placed in a set constant temperature environment for a corresponding preset time according to different temperature test conditions until it reaches a thermal equilibrium state.

5. The method for improving the accuracy of battery open circuit voltage testing according to claim 1, wherein: For each set battery SOC state, the OCV value is measured under different set temperature conditions, including: For each set SOC state of the battery, OCV values ​​are measured under different temperature conditions. Different SOC states of the battery include but are not limited to the following 35 key SOC states: 100%, 99%, 98%, 95%, 85%, 75%, 65%, 63%, 61%, 59%, 57%, 55%, 45%, 35%, 30%, 28%, 26%, 24%, 22%, 20%, 18%, 16%, 14%, 12%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, and 0%.

6. The method for improving the accuracy of battery open circuit voltage testing according to claim 1, wherein: Also includes: Based on the SOC-OCV correspondence data under different temperature conditions, a complete battery characteristic curve is established.

7. A system for improving the accuracy of battery open circuit voltage testing, characterized in that: include: The capacity determination module is used to obtain fresh batteries for capacity determination testing to determine the battery capacity; The SOC state adjustment module is used to adjust the battery's SOC state based on the capacity of the constant capacity test under a set constant temperature environment, and ensure that the battery returns to the set constant temperature before each adjustment; The measurement module is used to measure the OCV value under different set temperature conditions for each set SOC state of the battery, and obtain SOC-OCV data under different temperature conditions.

8. The system for improving battery open circuit voltage test accuracy according to claim 7, characterized in that: The SOC state adjustment module uses a capacity cutoff method to adjust the SOC state of the battery; before each adjustment of the SOC state of the battery, the battery is placed in a set constant temperature environment for a corresponding preset time according to different temperature test conditions until it reaches a thermal equilibrium state.

9. An electronic device, characterized in that: The processor, the communication interface, the memory and the communication bus are connected to each other via the communication bus. Memory for storing computer programs; A processor is configured to execute a program stored in a memory to implement the method for improving the accuracy of battery open circuit voltage testing according to any one of claims 1 to 6.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for improving the accuracy of battery open circuit voltage testing according to any one of claims 1 to 6 is implemented.

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