Battery capacity estimation method, device, and computer program

Abstract

A method, device and computer storage medium for estimating battery capacity are disclosed, which includes the steps of: acquiring a voltage-capacity curve of a battery in real time during a charging process of the battery (S110), obtaining a voltage difference-capacity curve by subtracting the voltage-capacity curve (S120), determining a voltage inflection point from the voltage-capacity curve based on the voltage difference-capacity curve, acquiring a reference capacity value corresponding to the pre-calibrated voltage inflection point (S170), acquiring a charging amount of electricity required to charge the battery from the voltage inflection point to a fully charged state (S180), and acquiring an actual capacity of the battery based on the sum of the reference capacity value and the charging amount of electricity (S190).

Description

[Technical Field]

[0001] This application claims priority to a Chinese patent application bearing application number 202111422355.6 and entitled "Battery capacity estimation method, apparatus and computer storage medium" filed with the State Intellectual Property Office of the People's Republic of China on November 26, 2021, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the technical field of battery processing, and in particular to a method, apparatus and computer storage medium for estimating battery capacity. [Background technology]

[0003] The strong public demand for new renewable energy solutions, such as electric vehicles, electric aircraft, and electric tankers, has led to the rapid development of lithium-ion batteries. Batteries applied in these systems face harsher operating conditions, including higher power and energy demands and greater temperature variations, all of which accelerate battery degradation. Therefore, it is necessary to track a battery's State of Health (SOH) and determine when it will reach the end of its useful life. SOH is typically defined as the ratio of a battery's actual capacity at a given time to its initial capacity.

[0004] Currently, battery capacity is calculated by fully charging or fully discharging a battery to calculate the total amount of electricity in the charging or discharging stage, or by charging or discharging within a certain battery State of Charge (SOC) range and calculating the total battery capacity based on the charged or discharged amount of electricity and the corresponding SOC range. The estimation accuracy of this method is entirely dependent on the accuracy of the SOC, and a large SOC estimation error will affect the accuracy of the battery capacity estimation. In particular, for lithium iron phosphate batteries, the accumulation of SOC errors affects the accuracy of the battery capacity, but battery capacity errors in turn affect the SOC accuracy, creating a cross-effect that ultimately leads to a completely invalid battery capacity estimation.

[0005] There are two drawbacks to using laboratory benchmarking. First, laboratory measurements are very time-consuming and expensive, and measurements under all operating conditions cannot be comprehensively performed. Second, benchmarking with laboratory data during actual use is dogmatic, and it is not possible to estimate the true capacity of the battery. Summary of the Invention

[0006] The "Summary of the Invention" introduces a series of simplified concepts, which are explained in more detail in the "Description of the Invention." The "Summary of the Invention" of this application is not intended to limit the key features and necessary technical features of the claimed technical means, nor is it intended to determine the scope of protection of the claimed technical means.

[0007] In order to solve the above technical problem, a method for estimating battery capacity according to a first aspect of an embodiment of the present application includes the steps of: acquiring a voltage-capacity curve of the battery in real time during a charging process of the battery; differential And the voltage differential - obtaining a capacity curve; differentialidentifying a plurality of peaks from the capacity curve; calculating a first height and a first width between each peak and its adjacent bottom on the left side, and a second height and a second width between each peak and its adjacent bottom on the right side; and calculating a decision index based on the first height, the first width, the second height, and the second width, where p=2(h1+w1) / (h1·w1)+2(h2+w2) / (h2·w2), where p represents the decision index, h1 represents the first height, w1 represents the first width, and h2 represents the second height. where w1 represents the second height and w2 represents the second width; determining a voltage inflection point in the voltage-capacity curve based on the peak at which the judgment index is minimum; obtaining a reference capacity value corresponding to the voltage inflection point in a pre-calibrated voltage-capacity curve; when the battery reaches a fully charged state, obtaining a charging amount of electricity required to charge the battery from the voltage inflection point to the fully charged state; and obtaining an actual capacity of the battery based on the sum of the reference capacity value and the charging amount of electricity.

[0008] The present invention estimates battery capacity based on the voltage inflection point on the voltage-capacity curve during the battery charging process, thereby improving the accuracy of battery capacity estimation, eliminating the need to fully discharge the battery, and conforming to user usage habits.

[0009] In one embodiment, the voltage-capacity curve is differential The method further includes smoothing and filtering the voltage-capacity curve before performing the voltage-capacity test.

[0010] In one embodiment, the reference capacity value is calibrated by fully discharging the battery and then charging it to a full charge state at a constant current, recording a reference voltage-capacity curve of the battery during the constant current charging process, and calibrating the reference capacity value based on the voltage-capacity curve during the constant current charging process.

[0011] In one embodiment, the step of obtaining the amount of charge electricity required to charge the battery from the voltage inflection point to a fully charged state includes the steps of: recording a charging time required to charge the battery from the voltage inflection point to a fully charged state; and calculating the amount of charge electricity based on the charging time and the charging current.

[0012] In one embodiment, the method further comprises estimating a state of health of the battery based on the actual capacity and a pre-calibrated initial capacity of the battery.

[0013] In one embodiment, the battery is a lithium iron phosphate battery.

[0014] In one embodiment, the initial capacity of a battery is determined by fully discharging the battery and then charging it to a full charge state at a constant current and recording the initial capacity of the battery.

[0015] In one embodiment, the step of estimating the state of health of the battery based on the actual capacity and the pre-calibrated initial capacity of the battery is based on the SOH=Q / Q new *100% included, where the actual capacity is represented by Q and the initial capacity is Q new and the battery's state of health is expressed as SOH.

[0016] A battery capacity estimation device according to a second aspect of an embodiment of the present application includes a memory and a processor, wherein the memory stores a computer program to be executed by the processor, and the computer program, when executed by the processor, executes the battery capacity estimation method.

[0017] A third aspect of an embodiment of the present application provides a computer storage medium storing a computer program that, when executed, implements the battery capacity estimation method.

[0018] The battery capacity estimation method and apparatus according to the embodiments of the present application estimates battery capacity based on the voltage inflection point on the voltage-capacity curve during the battery charging process, thereby improving the accuracy of battery capacity estimation regardless of the absolute value of the SOC, eliminating the need to fully discharge the battery, and conforming to user usage habits. [Brief explanation of the drawings]

[0019] The above and other objects, features, and advantages of the present application will become more apparent from a more detailed description of the embodiments of the present application, taken in conjunction with the accompanying drawings, which provide a further understanding of the embodiments of the present application, constitute a part of the specification, and explain the present application together with the embodiments of the present application, but do not limit the present application. In the drawings, like reference numerals generally represent like parts or steps.

[0020] [Figure 1] 1 is a schematic flowchart of a method for estimating battery capacity according to an embodiment of the present application; [Figure 2] FIG. 2 is a schematic diagram of a voltage-capacity curve according to an example of the present application. [Figure 3] FIG. 2 is a schematic diagram of a voltage differential-capacity curve according to an embodiment of the present application. [Figure 4] 1 is a schematic block diagram of a battery capacity estimation device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0021] In order to clarify the objectives, technical means, and advantages of the present application, exemplary embodiments of the present application will be described in detail below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, and are not all of the embodiments of the present application. It should be understood that the present application is not limited to the exemplary embodiments described herein. Any other embodiments that can be obtained by a person skilled in the art based on the embodiments of the present application described herein without any creative work are all within the scope of protection of the present application.

[0022] In the following description, many specific details are provided to provide a more thorough understanding of the present application. However, as will be apparent to those skilled in the art, the present application can be implemented without one or more of these details. In other instances, some technical features known in the art will not be described to avoid confusion with the present application.

[0023] As should be understood, the present application may be embodied in different forms and should not be construed as limited to the examples provided herein. Rather, these examples are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0024] The purpose of the terms used herein is to describe specific embodiments only and is not intended to limit the present application. As used herein, the singular forms "a," "one," and "the" are intended to include the plural forms unless the context clearly dictates otherwise. It is further understood that the terms "comprise" and / or "comprise," when used herein, determine the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. As used herein, the term "and / or" includes any and all combinations of the associated listed items.

[0025] In order to thoroughly understand the present application, the following description will provide a detailed structure to describe the technical means of the present application. Preferred embodiments of the present application will be described in detail as follows. In addition to these detailed descriptions, the present application may have other embodiments.

[0026] Hereinafter, a battery capacity estimation method and a battery capacity estimation device according to an embodiment of the present application will be described with reference to the drawings. First, Fig. 1 is a schematic flowchart of a battery capacity estimation method according to an embodiment of the present application. As shown in Fig. 1, the battery capacity estimation method includes steps S110 to S190.

[0027] In step S110, during the charging process of the battery, the voltage-capacity curve of the battery is obtained in real time.

[0028] In step S120, the voltage-capacity curve is differential And the voltage differential -Get the capacity curve.

[0029] In step S130, the voltage differential -Identify multiple peaks from the capacity curve.

[0030] In step S140, a first height and a first width between each peak and its adjacent bottom on the left side, and a second height and a second width between each peak and its adjacent bottom on the right side are calculated.

[0031] In step S150, a judgment index is calculated based on the first height, the first width, the second height, and the second width, where p=2(h1+w1) / (h1·w1)+2(h2+w2) / (h2·w2), where p represents the judgment index, h1 represents the first height, w1 represents the first width, h2 represents the second height, and w2 represents the second width.

[0032] In step S160, a voltage inflection point on the voltage-capacity curve is determined based on the peak at which the judgment index is minimum.

[0033] In step S170, a reference capacitance value corresponding to a voltage inflection point on a pre-calibrated voltage-capacity curve is obtained.

[0034] In step S180, when the battery reaches a fully charged state, the amount of charge electricity required to charge the battery from the voltage inflection point to the fully charged state is obtained.

[0035] In step S190, the actual capacity of the battery is obtained based on the sum of the reference capacity value and the charged amount of electricity.

[0036] The battery capacity estimation method according to the present embodiment detects the voltage-battery capacity curve during the battery charging process in real time, analyzes the curve characteristics, searches for voltage inflection points, and estimates the actual battery capacity based on the voltage inflection points. This method intelligently estimates the actual battery capacity based on the characteristic attributes of the materials themselves during the battery charging process, eliminating the need to deeply discharge the battery. Even when the initial SOC state of the battery is unknown, the actual battery capacity can be accurately calculated. Furthermore, the calculation process does not involve the absolute value of the SOC, so there is no cross-influence on the SOC calculation. The battery capacity estimation method according to the present embodiment not only significantly reduces laboratory measurement costs, but also significantly improves the efficiency and accuracy of battery capacity calculation. By estimating battery capacity based on the voltage inflection points on the voltage-capacity curve during the battery charging process, the present invention can improve the accuracy of battery capacity estimation, eliminate the need to fully discharge the battery, and accommodate user usage habits.

[0037] Specifically, during the charging process of a battery, the voltage-capacity curve of the battery is acquired in real time, and a voltage inflection point is determined from the voltage-capacity curve. The battery may include a lithium-ion battery, specifically a lithium iron phosphate battery. The voltage inflection point is one of several points at which the voltage changes most rapidly with capacity. The characteristics of the voltage-capacity curve and the voltage inflection point will be described below with reference to FIGS. 2 and 3.

[0038] First, Figure 2 shows the voltage-capacity curve of a lithium-ion battery. Generally, the voltage-capacity curve of a lithium-ion battery has three sections called voltage platform sections, where the voltage changes slowly with capacity. Between two adjacent voltage platform sections, there is a region where the voltage changes rapidly with capacity. The point where the voltage changes most rapidly within this region is called the voltage inflection point. In the present embodiment, the voltage inflection point for estimating the battery SOH is located between the second and third voltage platform sections, and is the point where the voltage changes most rapidly with capacity within this section.

[0039] Research has found that as lithium-ion batteries deteriorate, the difference between the battery capacity value corresponding to the voltage inflection point and the battery capacity value corresponding to SOC=0 (i.e., the capacity value is 0) remains unchanged. The embodiment of the present application estimates the actual capacity of a battery based on the characteristic of the voltage inflection point. After estimating the actual capacity of a battery, the battery's state of health (SOH) can be calculated based on the actual capacity of the battery. The SOH of a battery is the ratio of the actual capacity of the battery to its initial capacity. The initial capacity of a battery can be obtained by calibration before shipping. Specifically, the battery is fully discharged and then charged to a full charge state at a constant current to determine the initial capacity (Q new The embodiment of the present application calculates the actual capacity of the battery based on the voltage inflection point characteristic, thereby avoiding the need to calculate the actual capacity based on the SOC. This avoids the problem of the accumulation of SOC errors affecting the accuracy of the SOH estimation, and the SOH errors affecting the accuracy of the SOC.

[0040] Specifically, as described above, since the battery capacity value corresponding to the voltage inflection point remains unchanged, the embodiment of the present application identifies the voltage inflection point based on the voltage-capacity curve, and then calculates the amount of charge (QHVP) of the battery in the section from the voltage inflection point to the fully charged state of the battery. By adding the amount of charge and the capacity value (QHVTP) corresponding to the voltage inflection point, the actual capacity Q of the battery (Q=QHVP+QHVTP) can be obtained. The actual capacity Q of the battery and the pre-calibrated initial capacity Q new Based on the battery SOH (SOH=Q / Q new *100%).

[0041] Because the battery capacity in a voltage-capacity curve is calculated by a battery management system based on the SOC, to avoid introducing SOC errors, embodiments of the present application calculate the actual capacity of a battery using a pre-calibrated reference capacity value corresponding to a voltage inflection point. For example, before a battery is shipped, the battery is fully discharged and then charged to a fully charged state at a constant current. The voltage-capacity curve during the battery charging process is recorded, and the characteristics of the voltage-capacity curve are analyzed to determine the reference capacity value corresponding to the voltage inflection point by offline calibration. When calculating the amount of charge from the voltage inflection point to the fully charged state, the time to reach the voltage inflection point and the charging time to reach the fully charged state are recorded, and the amount of charge can be calculated based on the actual charging current and the charging time required to charge the battery from the voltage inflection point to the fully charged state. Because the reference capacity value corresponding to the voltage inflection point and the amount of charge are both accurate values, the accurate actual capacity of the battery can be obtained by adding them together.

[0042] The present embodiment does not depend on the absolute value of the SOC in the process of estimating the actual capacity of a battery, thereby avoiding the drawback of over-reliance on the accuracy of the SOC estimation when calculating the actual capacity of a battery in the conventional method. Furthermore, the present embodiment does not require the battery to be fully discharged, which is compatible with the usage habits of general users, and it has been experimentally proven that the actual capacity of a battery can be accurately calculated even when charging is started when the SOC is lower than 60%.

[0043] For example, a voltage inflection point is the point where voltage changes most rapidly with capacitance, so differential -The capacity curve can be determined based on the voltage inflection point. differential This corresponds to the peak of the voltage-capacity curve. differential and voltage differential -Capacitance (dV / dQ-Q) curve is obtained and the voltage differential -Based on the peak of the capacitance curve, determine the capacitance value corresponding to the voltage inflection point.

[0044] Voltage differentialA capacity curve generally has multiple peaks, and in order to determine the voltage inflection points, it is necessary to determine characteristic peaks among those peaks, i.e., peaks corresponding to the voltage inflection points. In the embodiment of the present application, characteristic peaks are searched for based on the ratio of the perimeter to the area of ​​each peak, and the voltage inflection points determined based on the characteristic peaks are voltage inflection points that satisfy the capacity constancy characteristic.

[0045] Specifically, as shown in Figure 3, first, the voltage differential - Identifying a plurality of peaks from the capacitance curve, and calculating a first height and a first width between each peak and its adjacent bottom to the left, and a second height and a second width between each peak and its adjacent bottom to the right, the first height being the voltage difference between each peak and its adjacent bottom to the left. differential The first width is the difference in capacitance between each peak and its adjacent bottom to the left, and the second height is the difference in voltage between each peak and its adjacent bottom to the right. differential The second width is the absolute value of the difference in capacitance between each peak and its adjacent bottom on the right side.

[0046] Then, a judgment index is calculated for each peak based on the first height, first width, second height, and second width, and the sum of the ratios of the circumference and area of ​​the left and right halves of each peak is used as the judgment index. Specifically, judgment index p = 2(h1 + w1) / (h1 · w1) + 2(h2 + w2) / (h2 · w2), where h1 represents the first height, w1 represents the first width, h2 represents the second height, and w2 represents the second width. After calculating the judgment index for each peak, the peak with the smallest judgment index is taken as the characteristic peak and the voltage inflection point is determined.

[0047] In some embodiments, the voltage-capacity curve is differential The method further includes smoothing and filtering the voltage-capacity curve before determining the voltage inflection point. After determining the voltage inflection point, the actual capacity of the battery can be estimated as described above.

[0048] The present embodiment detects and analyzes the voltage-capacity curve in real time during the battery charging process, eliminating the need for deep discharging the battery and adapting to user usage habits, resulting in significant technical advantages and market value. The calculation process does not require determining the initial SOC of the battery. Rather, the actual battery capacity can be calculated simply by identifying voltage inflection points during the charging process, regardless of the absolute value of the SOC. This improves the accuracy of estimating the actual battery capacity. Furthermore, the SOH of the battery can be obtained, improving the accuracy and speed of SOH estimation. Furthermore, the voltage inflection points are automatically identified using perimeter / area features, eliminating the need to manually set thresholds based on the vehicle model and level of deterioration, resulting in greater versatility.

[0049] The present embodiment further provides a battery capacity estimation device for implementing the battery capacity estimation method. Figure 4 is a schematic block diagram of a battery capacity estimation device 400 according to the present embodiment.

[0050] 4 , the battery capacity estimation device 400 includes a memory 410, a processor 420, and a computer program stored in the memory 410 and executed on the processor 420. When the processor 420 executes the computer program, the battery capacity estimation method can be realized. The processor 420 may be implemented by software, hardware, firmware, or a combination thereof, and may use at least one of a circuit, one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), central processing units (CPUs), controllers, microcontrollers, and microprocessors, so that the device can perform some, all, or any combination of steps of the battery capacity estimation method in each embodiment of the present application.

[0051] An embodiment of the present application further provides a computer storage medium having stored thereon a computer program that, when executed, can implement the method for estimating battery capacity according to an embodiment of the present application.

[0052] The battery capacity estimation device 400 and computer storage medium according to the embodiment of the present application also have similar advantages for implementing the battery capacity estimation method.

[0053] Although exemplary embodiments have been described herein with reference to the drawings, it should be understood that the exemplary embodiments are merely illustrative and are not intended to limit the scope of the present application. Those skilled in the art may make various changes and modifications without departing from the scope and spirit of the present application. All such changes and modifications are intended to be included within the scope of the present application as defined in the appended claims.

[0054] Those skilled in the art can recognize that the units and algorithm steps of each example described in the embodiments disclosed herein can be combined and realized in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in the form of hardware or software depends on the specific application and design constraints of the technical means. Those skilled in the art may implement the described functions in different ways for each specific application, but such implementation should not be considered to go beyond the scope of the present application.

[0055] It should be understood that in some embodiments of the present application, the disclosed devices and methods can be realized in other ways. For example, the device embodiments described above are merely schematic, and the division of each unit is merely a logical division of function. In actual implementation, other division methods may be used. For example, multiple units or components may be combined or integrated into another device, and some features may be ignored or not implemented.

[0056] In the specification provided herein, many specific details are set forth. However, it will be understood that embodiments of the present application may be practiced without these specific details. In some embodiments, well-known methods, structures, and techniques are not shown in detail in order not to obscure an understanding of this specification.

[0057] Similarly, it will be understood that in the description of exemplary embodiments of the present application, features of the present application may be grouped together in a single embodiment, figure, or description to simplify the present application and facilitate understanding of one or more of the inventive aspects. However, this method should not be interpreted as reflecting an intention that the claimed application requires more features than are expressly recited in each claim. More specifically, as the corresponding claims reflect, the inventive concept may solve the corresponding technical problem using fewer than all features of a single disclosed embodiment. Therefore, the claims according to specific embodiments are expressly incorporated into the specific embodiments, with each claim itself being a separate embodiment of the present application.

[0058] As will be understood by those skilled in the art, all features disclosed in this specification (including the accompanying claims, abstract and drawings) and all processes or units of any method or apparatus so disclosed may be combined using any combination other than mutual exclusivity between features. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract and drawings) may be replaced with an alternative feature serving the same, equivalent or similar purpose.

[0059] Furthermore, as will be understood by those skilled in the art, although some embodiments described herein may include some features included in other embodiments but not other features included in other embodiments, a combination of features from different embodiments is within the scope of the present application and means to form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

[0060] Various component embodiments of the present application may be implemented in hardware, software modules running on one or more processors, or a combination thereof. As will be appreciated by those skilled in the art, a microprocessor or digital signal processor (DSP) may actually be used to implement some or all of the functionality of some modules according to the present application. The present application may also be implemented as an apparatus program (e.g., a computer program and computer program product) that executes some or all of the methods described herein. Such programs implementing the present application may be stored on a computer-readable medium or may have the form of one or more signals. Such signals may be downloaded from an Internet site, provided on a carrier signal, or provided in other formats.

[0061] It should be noted that the above embodiments are illustrative of the present application, not limiting, and that those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs in parentheses shall not be construed as limiting the scope of the claims. The present application may be realized by hardware comprising several different elements and by a suitably programmed computer. In a unit claim enumerating several devices, several of such devices may be embodied by the same hardware. The use of terms such as first, second, and third does not indicate any order. Such terms may be construed as names.

[0062] The above description is merely a specific embodiment or description of a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto, and any changes or substitutions that a person skilled in the art can easily make within the technical scope disclosed in the present application should be included in the scope of protection of the present application. The scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. During the charging process of the battery, a voltage-capacity curve of the battery is acquired in real time (S110); Differentiating the voltage-capacity curve to obtain a voltage differential-capacity curve (S120); Identifying a plurality of peaks from the voltage derivative-capacity curve (S130); calculating (S140) a first height and a first width between each peak and an adjacent end of a voltage platform section to the left of the peak where the voltage differential is smaller and more constant than that near the peak, and a second height and a second width between each peak and an adjacent end of a voltage platform section to the right of the peak where the voltage differential is smaller and more constant than that near the peak; a step (S150) of calculating a judgment index based on the first height, the first width, the second height, and the second width, where p=2(h1+w1) / (h1·w1)+2(h2+w2) / (h2·w2), where p represents the judgment index, h1 represents the first height, w1 represents the first width, h2 represents the second height, and w2 represents the second width; determining a voltage inflection point in the voltage-capacity curve based on the peak at which the judgment index is minimum (S160); Before shipping the battery, fully discharge the battery and then charge it to a fully charged state at a constant current to obtain a voltage-capacity curve during the charging process of the battery, and obtain a reference capacity value corresponding to the charge amount from the fully discharged state to the voltage inflection point on the voltage-capacity curve (S170); After the battery reaches a fully charged state, a charging amount of electricity required to charge the battery from the voltage inflection point to a fully charged state is obtained (S180); and acquiring (S190) an actual capacity of the battery based on the sum of the reference capacity value and the charged amount of electricity.

2. 2. The method of claim 1, further comprising the step of smoothing and filtering the voltage-capacity curve before differentiating the voltage-capacity curve.

3. 2. The method of claim 1, wherein the reference capacity value is calibrated by fully discharging the battery and then charging it to a full charge state at a constant current, recording a voltage-capacity curve of the battery during the constant current charging process, and calibrating the reference capacity value based on the voltage-capacity curve of the battery during the constant current charging process.

4. The step of acquiring the amount of charge electricity required to charge the battery from the voltage inflection point to a fully charged state includes: recording the charging time required to charge the battery from the voltage inflection point to a fully charged state; Calculating the charged quantity of electricity based on the charging time and charging current.

5. The method for estimating a battery capacity according to any one of claims 1 to 4, further comprising the step of estimating a state of health of the battery based on the actual capacity and a pre-calibrated initial capacity of the battery.

6. The method for estimating battery capacity according to any one of claims 1 to 4, wherein the battery is a lithium iron phosphate battery.

7. 6. The method of estimating battery capacity according to claim 5, wherein the initial capacity of the battery is determined by fully discharging the battery and then charging it to a fully charged state at a constant current, and recording the initial capacity of the battery.

8. The step of estimating the state of health of the battery based on the actual capacity and the pre-calibrated initial capacity of the battery is carried out by: SOH=Q / Q ｎｅｗ *100%, where the actual capacity is represented by Q and the initial capacity is Q ｎｅｗ and the state of health of the battery is expressed as SOH.

9. The present invention includes a memory (410) and a processor (420), wherein the memory (410) stores a computer program that is executed by the processor (420), and the computer program, when executed by the processor (420), performs the following: During the charging process of the battery, acquiring a voltage-capacity curve of the battery in real time; differentiating the voltage-capacity curve to obtain a voltage differential-capacity curve; identifying a plurality of peaks from the voltage derivative vs. capacity curve; calculating a first height and a first width between each peak and an adjacent end of a voltage platform section to the left of the peak where the voltage derivative is smaller and more constant than near the peak, and a second height and a second width between each peak and an adjacent end of a voltage platform section to the right of the peak where the voltage derivative is smaller and more constant than near the peak; calculating a judgment index based on the first height, the first width, the second height, and the second width, where p=2(h1+w1) / (h1·w1)+2(h2+w2) / (h2·w2), where p represents the judgment index, h1 represents the first height, w1 represents the first width, h2 represents the second height, and w2 represents the second width; determining a voltage inflection point in the voltage-capacity curve based on the peak at which the judgment index is minimum; Before shipping the battery, fully discharge the battery and then charge it at a constant current until it is fully charged, thereby obtaining a voltage-capacity curve during the battery charging process, and obtaining a reference capacity value corresponding to the charge amount from the fully discharged state to the voltage inflection point on the voltage-capacity curve; After the battery reaches a fully charged state, a charging amount of electricity required to charge the battery from the voltage inflection point to a fully charged state is acquired; and acquiring an actual capacity of the battery based on the sum of the reference capacity value and the charged amount of electricity.

10. 10. The battery capacity estimation device (400) of claim 9, wherein before differentiating the voltage-capacity curve, the computer program further performs the steps of smoothing and filtering the voltage-capacity curve.

11. 10. The battery capacity estimation device (400) of claim 9, wherein the reference capacity value is calibrated by fully discharging the battery and then charging it to a fully charged state at a constant current, recording a voltage-capacity curve of the battery during the constant current charging process, and calibrating the reference capacity value based on the voltage-capacity curve of the battery during the constant current charging process.

12. The step of acquiring the amount of charge electricity required to charge the battery from the voltage inflection point to a fully charged state includes: recording the charging time required to charge the battery from the voltage inflection point to a fully charged state; 10. The battery capacity estimation device (400) of claim 9, further comprising the step of: calculating the charged quantity of electricity based on the charging time and charging current.

13. The battery capacity estimation device (400) of claim 9, wherein the computer program further executes a step of estimating a state of health of the battery based on the actual capacity and a pre-calibrated initial capacity of the battery.

14. The battery capacity estimation device (400) according to any one of claims 9 to 13, wherein the battery is a lithium iron phosphate battery.

15. A computer program that, when executed, During the charging process of the battery, acquiring a voltage-capacity curve of the battery in real time; differentiating the voltage-capacity curve to obtain a voltage differential-capacity curve; identifying a plurality of peaks from the voltage derivative vs. capacity curve; calculating a first height and a first width between each peak and an adjacent end of a voltage platform section to the left of the peak where the voltage derivative is smaller and more constant than near the peak, and a second height and a second width between each peak and an adjacent end of a voltage platform section to the right of the peak where the voltage derivative is smaller and more constant than near the peak; calculating a judgment index based on the first height, the first width, the second height, and the second width, where p=2(h1+w1) / (h1·w1)+2(h2+w2) / (h2·w2), where p represents the judgment index, h1 represents the first height, w1 represents the first width, h2 represents the second height, and w2 represents the second width; determining a voltage inflection point in the voltage-capacity curve based on the peak at which the judgment index is minimum; Before shipping the battery, fully discharge the battery and then charge it at a constant current until it is fully charged, thereby obtaining a voltage-capacity curve during the battery charging process, and obtaining a reference capacity value corresponding to the charge amount from the fully discharged state to the voltage inflection point on the voltage-capacity curve; After the battery reaches a fully charged state, a charging amount of electricity required to charge the battery from the voltage inflection point to a fully charged state is acquired; and acquiring an actual capacity of the battery based on the sum of the reference capacity value and the charged amount of electricity.

16. The computer program of claim 15 , wherein the computer program further implements the step of smoothing and filtering the voltage-capacity curve before differentiating the voltage-capacity curve.

17. 16. The computer program of claim 15, wherein the reference capacity value is calibrated by fully discharging the battery and then charging it to a full charge state at a constant current, recording a voltage-capacity curve of the battery during the constant current charging process, and calibrating the reference capacity value based on the voltage-capacity curve of the battery during the constant current charging process.

18. The step of acquiring the amount of charge electricity required to charge the battery from the voltage inflection point to a fully charged state includes: recording the charging time required to charge the battery from the voltage inflection point to a fully charged state; and calculating the charged quantity of electricity based on the charging time and charging current.

19. The computer program of claim 15 , further comprising estimating a state of health of the battery based on the actual capacity and a pre-calibrated initial capacity of the battery.

20. The computer program according to any one of claims 15 to 19, wherein the battery is a lithium iron phosphate battery.

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