State of charge calibration methods, battery management systems and energy storage devices

Abstract

This application relates to battery management technology. The purpose of this application is to provide a state-of-charge (POC) calibration method, a battery management system, and an energy storage device, aiming to solve the problem that traditional battery management systems cannot guarantee the accuracy of POC calibration without a clock chip. The POC calibration method includes: responding to a wake-up operation of the energy storage device, real-time monitoring of the current battery current value of the battery module of the energy storage device; starting a timer if the current battery current value is less than a preset threshold; and performing POC calibration when the current battery current value remains below the preset threshold and the timer duration reaches the set rest period. The advantage of this application is that it eliminates the need for a separate clock chip. It is applicable to POC calibration of energy storage devices.

Description

Technical Field

[0001] This application belongs to the field of battery management technology, and particularly relates to a state of charge calibration method, a battery management system and an energy storage device. Background Technology

[0002] Currently, energy storage devices generally include a battery management system (BMS), and all BMS systems have a state of charge (SOC) calibration function. However, some BMS systems do not install a separate clock chip in order to save costs. As a result, these BMS systems cannot calculate the time when they are in sleep mode, and therefore cannot accurately determine whether the battery has been sufficiently rested after waking up. Only when the battery has been sufficiently rested can the accuracy of calibrating the state of charge by consulting the battery open circuit voltage (OCV) table be guaranteed.

[0003] Therefore, traditional energy storage devices' battery management systems cannot guarantee the accuracy of state-of-charge calibration without installing a clock chip. Summary of the Invention

[0004] The purpose of this application is to provide a state of charge calibration method, a battery management system, and an energy storage device, aiming to solve the problem that traditional battery management systems cannot guarantee the accuracy of state of charge calibration without installing a clock chip.

[0005] The first aspect of this application provides a state of charge calibration method applied to an energy storage device; the state of charge calibration method includes:

[0006] In response to the wake-up operation of the energy storage device, the current battery current value of the battery module of the energy storage device is monitored in real time. If the current battery current value is less than a preset threshold, then timing begins; When the current battery current value is continuously less than the preset threshold and the timing duration reaches the preset resting time, the state of charge calibration is performed.

[0007] In one embodiment, the method further includes: If the current battery current value is greater than or equal to a preset threshold before the timeout period reaches the preset rest period, the timeout period will be reset to zero.

[0008] In one embodiment, the step of performing state of charge calibration when the current battery current value is continuously less than the preset threshold and the timing duration reaches the preset resting time includes: Obtain the current internal resistance and current voltage of the battery module; Calculate the current battery open-circuit voltage value based on the current battery internal resistance value, the current battery voltage value, and the current battery current value; The target state of charge is located based on the current battery open-circuit voltage value, and the state of charge is calibrated based on the target state of charge.

[0009] In one embodiment, calculating the current battery open-circuit voltage value based on the current battery internal resistance value, the current battery voltage value, and the current battery current value includes: multiplying the current battery current value and the current battery internal resistance value to obtain a product, and subtracting the product from the current battery voltage value to obtain the current battery open-circuit voltage value.

[0010] In one embodiment, obtaining the current internal resistance value of the battery module includes: Collect the current battery temperature and current state of charge of the battery module; The current internal resistance of the battery is determined based on the current battery temperature and the current state of charge.

[0011] In one embodiment, determining the current battery internal resistance value based on the current battery temperature and the current state of charge includes: In a preset mapping table, the internal resistance value corresponding to the current battery temperature and the current state of charge is found. The preset mapping table includes the correspondence between each battery temperature, each state of charge, and the internal resistance value.

[0012] In one embodiment, the method further includes: Under various preset test conditions, a preset current pulse is applied to the battery within a preset time; wherein the preset battery temperature and / or preset state of charge are different in each preset test condition. The voltage change value is obtained, and the voltage change value is the difference between the voltage value of the battery before the preset current pulse is applied and the voltage value of the battery after the preset current pulse is applied; The battery internal resistance value under each preset test condition is calculated based on the voltage change value and the preset current pulse.

[0013] In one embodiment, the calibration of the state of charge based on the target state of charge includes: Obtain the difference between the target state of charge and the current state of charge; The correction factor is determined based on the difference. The current state of charge is calibrated according to the correction factor so that the current state of charge is consistent with the target state of charge.

[0014] A second aspect of this application provides a battery management system disposed within an energy storage device. The battery management system is connected to the battery module of the energy storage device. The battery management system includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the state-of-charge calibration method as described above.

[0015] A third aspect of this application provides an energy storage device, characterized in that the energy storage device includes a battery module and a battery management system, the battery management system being connected to the battery module, and the battery management system being used to implement the state of charge calibration method as described above when executing a computer program.

[0016] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows: When timing is performed, the above-mentioned state of charge calibration method can be performed using the system's built-in system time. When the battery current value is detected to be less than the preset threshold for a preset resting time, it is determined that the current battery has been sufficiently rested, and then the state of charge calibration is performed. Thus, it is not necessary to use a separate clock chip to determine whether the battery has been sufficiently rested, making the state of charge calibration more accurate. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of the state of charge calibration method provided in the first aspect of the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the battery management system provided in the second aspect of the embodiments of this application; Figure 3 This is a schematic diagram of the structure of an energy storage device provided in the third aspect of the embodiments of this application; Figure 4 This is a schematic diagram of the structure of the state of charge calibration device provided in the fourth aspect of the embodiments of this application. Detailed Implementation

[0018] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0019] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0020] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0021] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0022] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0024] Figure 1 A schematic flowchart of a state of charge calibration method provided in the first aspect of this application is shown. This is an example and not a limitation; the method can be applied to energy storage devices. The state of charge calibration method includes: S101, In response to the wake-up operation of the energy storage device, monitor the current battery current value of the battery module of the energy storage device in real time.

[0025] In this step, the device responding to the wake-up operation of the energy storage device should be the corresponding device that applies the state of charge calibration method, such as the battery management system inside the energy storage device. The wake-up operation includes, for example, waking up the battery management system. After waking up, the device can monitor the current battery current value of the battery module in real time through its connection with the battery module.

[0026] S102. If the current battery current value is less than the preset threshold, start timing.

[0027] It is understandable that in this step, timing can be performed using the system's built-in system time, thus allowing the state of charge calibration method to be applied to energy storage devices that do not have a separate clock chip.

[0028] S103. When the current battery current value is continuously less than the preset threshold and the timing duration reaches the preset resting time, perform state of charge calibration.

[0029] It should be noted that for a certain battery cell (i.e., battery module), its preset resting time is a certain period of time. This preset resting time is determined when the battery cell leaves the factory. It is a parameter determined by the battery cell itself and can be stored in the memory of the energy storage device in advance.

[0030] Understandably, since this step has determined that the battery module has reached the preset resting time, the state of charge can be calibrated directly by querying the OCV table or other methods.

[0031] In some embodiments, the preset threshold can be set according to the actual situation, for example, set to 0.1C, regardless of whether the current battery is in a charging or discharging state.

[0032] Specifically, since the current battery current value may be greater than or equal to a preset threshold before the timing period reaches the preset resting time, in order to propose a handling method for this situation, the state of charge calibration method may further include the following steps: If the current battery current value is greater than or equal to the preset threshold before the timer reaches the preset rest period, the timer will be reset to zero.

[0033] That is, if the current battery current value is greater than or equal to the preset threshold before the timer reaches the preset rest time, no further steps will be taken and the timer will be reset to zero. At this time, it is equivalent to returning to the untimed state. Therefore, when the current battery current value is less than the preset threshold again, the timer will restart.

[0034] In one possible implementation, since the battery open-circuit voltage value cannot be obtained directly, and there is a one-to-one correspondence between the current battery open-circuit voltage value and the target state of charge, it is required that the acquisition of the current battery open-circuit voltage value be as accurate as possible. Therefore, the method for performing state of charge calibration in step S103 may include the following steps: Obtain the current internal resistance and current voltage of the battery module; Calculate the current open-circuit voltage of the battery based on the current internal resistance, current voltage, and current current. Find the target state of charge based on the current battery open-circuit voltage value, and then calibrate the state of charge based on the target state of charge.

[0035] It is understandable that when performing state of charge calibration in the above steps, the current battery open-circuit voltage value is calculated based on the current battery internal resistance value, the current battery voltage value, and the current battery current value. The current battery voltage value and the current battery current value can be obtained directly through monitoring and are very accurate. Therefore, the current battery internal resistance value is relatively accurate, and the calculated current battery open-circuit voltage value is also relatively accurate.

[0036] To find the target state of charge based on the current battery open-circuit voltage, you can look up the OCV (Optical Value Table) using the current battery open-circuit voltage. This OCV is preset in the energy storage device and is a parameter determined by the battery module itself. For example, the OCV of a certain battery cell can be found in Table 1.

[0037] Table 1. OCV table for a certain type of battery cell SOC (%) 0 10 20 30 40 50 60 70 80 90 100 Voltage (mV) 3353 3488 3566 3619 3652 3707 3821 3931 4048 4168 4315 Specifically, this application also proposes a formula for calculating the current battery open-circuit voltage value. The formula for calculating the current battery open-circuit voltage value based on the battery internal resistance, current battery voltage, and current battery current is as follows: ; Among them, V ocv V represents the current open-circuit voltage of the battery. bms I represents the current battery voltage value. bms R is the current battery current value, and R is the battery internal resistance value.

[0038] It should be noted that since the battery's internal resistance changes with battery temperature and state of charge, directly obtaining the current battery internal resistance is not easy, and if the method for obtaining the current battery internal resistance is too complex, it will overload the system. Therefore, in this embodiment, the following method can be used to obtain the current battery internal resistance: Collect the current battery temperature and current state of charge of the battery module; Determine the battery's internal resistance based on the current battery temperature and current state of charge.

[0039] Understandably, since the main factors affecting the battery's internal resistance are battery temperature and state of charge (SOC), the battery's internal resistance can be determined based on the current battery temperature and SOC. Similarly, the device that collects the current battery temperature and SOC of the battery module should be a device that applies this SOC calibration method, such as the battery management system within an energy storage device.

[0040] Optionally, to simplify the process of determining the current battery internal resistance and save system resources, determining the current battery internal resistance based on the current battery temperature and current state of charge may include the following steps: In the preset mapping table, find the internal resistance value corresponding to the current battery temperature and the current state of charge. The preset mapping table includes the correspondence between each battery temperature, each state of charge and the internal resistance value.

[0041] Therefore, the corresponding internal resistance value can be looked up in a preset mapping table based on the current battery temperature and current state of charge. The found internal resistance value is the current battery internal resistance value. Since a preset mapping table is available, and the battery internal resistance value is determined by looking up the table, it is no longer necessary to calculate or sample the battery internal resistance value, saving system resources. The preset mapping table can be directly stored in the internal memory of the corresponding energy storage device before the device leaves the factory.

[0042] In some embodiments, since the battery internal resistance includes the instantaneous ohmic internal resistance and the polarization internal resistance after the battery polarization reaction, the calculation of the correspondence between each battery temperature and each state of charge and the internal resistance value in the preset mapping table is relatively complex. Therefore, the state of charge calibration method in this embodiment may further include the following steps: Under various preset test conditions, a preset current pulse is applied to the battery within a preset time; wherein the preset battery temperature and / or preset state of charge are different in each preset test condition. The voltage change value is obtained. The voltage change value is the difference between the battery voltage value before the preset current pulse is applied and the battery voltage value after the preset current pulse is applied. Calculate the battery internal resistance value under each preset test condition based on the voltage change value and the preset current pulse.

[0043] Understandably, the above method, by testing the batteries, identifies the correspondence between each battery's temperature, state of charge, and internal resistance value. This yields internal resistance values ​​that include both instantaneous ohmic resistance and polarization resistance after the battery's polarization reaction, thus avoiding the need to calculate both ohmic and planned internal resistance separately. Furthermore, the calculated battery internal resistance values ​​under various preset test conditions are compiled into a corresponding preset mapping table.

[0044] The preset time and the size of the preset current pulse can be set according to the actual situation. For example, if the preset time is set to 20 seconds and the size of the preset current pulse is 1C, the preset mapping table of a certain battery cell can be found in Table 2. In Table 2, the temperature is in °C, the SOC is in %, and the internal resistance is in uohm.

[0045] Table 2. Preset mapping table for a certain type of battery cell SOC temperature 0 10 20 30 40 50 60 70 80 90 100 -10 5500 4500 3456 2722 2326 2273 2204 2191 2223 2293 2391 0 4953 4047 1819 1510 1377 1318 1300 1309 1341 1393 1461 10 1914 1451 1016 884 830 810 810 822 846 880 924 25 1232 682 548 509 496 493 498 506 520 537 559 40 639 451 407 395 392 392 396 401 408 417 427 50 496 400 378 373 372 373 375 379 383 389 397 Optionally, since there may be a large difference between the target state of charge and the current state of charge, in order to prevent the displayed current state of charge from instantly changing to the target state of charge with a large difference, the calibration of the state of charge based on the target state of charge may include the following steps: Obtain the difference between the target state of charge and the current state of charge; The correction factor is determined based on the difference. The current state of charge is calibrated according to the correction factor to make the current state of charge consistent with the target state of charge.

[0046] It is understandable that since the energy storage device obtains relevant information from the battery module at regular intervals to calculate the current state of charge, the current state of charge can be changed step by step to the target state of charge with a large difference after the correction factor is introduced.

[0047] Meanwhile, when using a preset mapping table, the battery's internal resistance is obtained from the current battery temperature and current state of charge (SOC). However, the current SOC is not the accurate target SOC, thus introducing a certain degree of error. By introducing a correction factor, the target SOC obtained at each stage of change in the current SOC will also be corrected, thereby reducing the error.

[0048] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0049] Figure 2 A schematic structural block diagram of a battery management system 101 provided in the second aspect of an embodiment of this application is shown. For ease of explanation, only the parts related to the embodiment of this application are shown.

[0050] Reference Figure 2 The battery management system 101 is installed in the energy storage device and is connected to the battery module 102 of the energy storage device. The battery management system 101 includes a memory 1012, a processor 1011 and a computer program stored in the memory 1012 and executable on the processor 1011. When the processor 1011 executes the computer program, it implements the state of charge calibration method as described above.

[0051] Figure 3 A schematic structural block diagram of an energy storage device 10 provided in the third aspect of an embodiment of this application is shown. For ease of explanation, only the parts related to the embodiments of this application are shown.

[0052] Reference Figure 3The energy storage device 10 includes a battery module 102 and a battery management system 101. The battery management system 101 is connected to the battery module 102 and is used to implement the state of charge calibration method as described above when executing a computer program.

[0053] Figure 4 A schematic structural block diagram of a state of charge calibration device 20 provided in the fourth aspect of an embodiment of this application is shown. For ease of explanation, only the parts related to the embodiments of this application are shown.

[0054] Reference Figure 4 The state of charge calibration device 20 includes: Monitoring unit 201, in response to the wake-up operation of the energy storage device, monitors the current battery current value of the battery module of the energy storage device in real time; The timing unit 202 is used to start timing if the current battery current value is less than a preset threshold. The calibration unit 203 is used to perform state of charge calibration when the current battery current value is continuously less than a preset threshold and the timing duration reaches a preset resting time.

[0055] It should be noted that the information interaction and execution process between the above-mentioned devices / units / modules are based on the same concept as the method embodiments of this application. For details on their specific functions and technical effects, please refer to the method embodiments section, and they will not be repeated here.

[0056] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0057] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of this application can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying the computer program code to a photographing device / terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks.

[0058] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0059] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0060] In the embodiments provided in this application, it should be understood that the disclosed apparatus / network devices and methods can be implemented in other ways. For example, the apparatus / network device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0061] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0062] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

[0063] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for calibrating the state of charge, characterized in that, Applications in energy storage devices; The state of charge calibration method includes: In response to the wake-up operation of the energy storage device, the current battery current value of the battery module of the energy storage device is monitored in real time. If the current battery current value is less than a preset threshold, the timing will start using the system's built-in system time. When the current battery current value is continuously less than the preset threshold and the timing duration reaches the preset resting time, a state of charge calibration is performed, including: obtaining the current battery internal resistance value and the current battery voltage value of the battery module; calculating the current battery open circuit voltage value based on the current battery internal resistance value, the current battery voltage value, and the current battery current value; finding the target state of charge based on the current battery open circuit voltage value; and calibrating the state of charge based on the target state of charge. The step of obtaining the current internal resistance value of the battery module includes: collecting the current battery temperature and current state of charge of the battery module; and determining the current internal resistance value of the battery based on the current battery temperature and current state of charge. The calibration of the state of charge based on the target state of charge includes: obtaining the difference between the target state of charge and the current state of charge; determining a correction factor based on the difference; calibrating the current state of charge based on the correction factor. After introducing the correction factor, when the current state of charge changes at each level, the subsequently obtained target state of charge will also be corrected, changing the displayed current state of charge level by level to the target state of charge with a larger difference, so that the current state of charge is consistent with the target state of charge.

2. The state of charge calibration method as described in claim 1, characterized in that, The method further includes: If the current battery current value is greater than or equal to a preset threshold before the timeout period reaches the preset rest period, the timeout period will be reset to zero.

3. The state of charge calibration method as described in claim 1, characterized in that, The step of calculating the current battery open-circuit voltage value based on the battery internal resistance value, the current battery voltage value, and the current battery current value includes: The product is obtained by multiplying the current battery current value by the current battery internal resistance value; Subtract the product from the current battery voltage value to obtain the current battery open-circuit voltage value.

4. The state of charge calibration method as described in claim 1, characterized in that, Determining the current battery internal resistance value based on the current battery temperature and the current state of charge includes: In a preset mapping table, the internal resistance value corresponding to the current battery temperature and the current state of charge is found. The preset mapping table includes the correspondence between each battery temperature, each state of charge, and the internal resistance value.

5. The state of charge calibration method as described in claim 4, characterized in that, The method further includes: Under various preset test conditions, a preset current pulse is applied to the battery within a preset time; wherein the preset battery temperature and / or preset state of charge are different in each preset test condition. The voltage change value is obtained, and the voltage change value is the difference between the voltage value of the battery before the preset current pulse is applied and the voltage value of the battery after the preset current pulse is applied; The battery internal resistance value under each preset test condition is calculated based on the voltage change value and the preset current pulse.

6. A battery management system, characterized in that, The battery management system is installed within the energy storage device and is connected to the battery module of the energy storage device. The battery management system includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the state of charge calibration method as described in any one of claims 1-5.

7. An energy storage device, characterized in that, The energy storage device includes a battery module and a battery management system, the battery management system being connected to the battery module, and the battery management system being used to implement the state of charge calibration method as described in any one of claims 1-5 when executing a computer program.

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