Detection method, detection device and electric device

Abstract

The embodiment of the invention discloses a detection method, a detection device and a power utilization device, the detection method is used for detecting the SOC of a single battery, and the detection method comprises the steps: obtaining a plurality of terminal voltages of the single battery corresponding to a plurality of moments in a first time period after the single battery is charged or discharged; according to the multiple moments and the multiple terminal voltages, a first mapping relation between the terminal voltages and the time is determined, and the first mapping relation converges under the condition that the time tends to be positive infinity; determining a steady-state voltage according to the terminal voltage of the first mapping relation under the condition that the time tends to be positive infinity; and the SOC of the single battery is determined according to the steady-state voltage, so that the reliability of SOC estimation of the single battery can be improved.

Description

Technical Field

[0001] This application relates to the field of battery testing technology, and more specifically, to a testing method, a testing device, and an electrical device. Background Technology

[0002] Monitoring the state of charge (SOC) of individual battery cells is crucial during the use or charging of electrical devices. Obtaining the SOC of a battery cell helps users determine the charging and usage time based on the remaining charge. However, current methods for estimating the SOC of individual battery cells suffer from problems such as long estimation time and low accuracy, resulting in relatively low reliability.

[0003] Therefore, improving the reliability of single-cell SOC estimation has become an urgent problem to be solved. Summary of the Invention

[0004] This application provides a detection method, a detection device, and an electrical device that can improve the reliability of battery cell SOC estimation.

[0005] In a first aspect, a detection method is provided for detecting the state of charge (SOC) of a battery cell. The detection method includes: acquiring multiple terminal voltages of the battery cell at multiple times within a first time period after the battery cell has been charged or discharged; determining a first mapping relationship between the terminal voltage and time based on the multiple times and the multiple terminal voltages, wherein the first mapping relationship converges as time approaches positive infinity; determining a steady-state voltage based on the terminal voltage as time approaches positive infinity based on the first mapping relationship; and determining the SOC of the battery cell based on the steady-state voltage.

[0006] In the technical solution provided in this application, by sampling the terminal voltage at multiple moments within a first time period after a battery cell is charged or discharged, and fitting a first mapping relationship between the battery cell terminal voltage and time based on multiple pairs of time-terminal voltage data, the steady-state voltage of the battery cell can be estimated using short-time sampled data, thereby quickly obtaining the SOC of the battery cell. Simultaneously, the first mapping relationship converges at positive infinity, which improves the similarity between the estimated terminal voltage and the true value, thereby improving the accuracy of the SOC estimation and thus enhancing the reliability of the battery cell SOC estimation.

[0007] In some embodiments, determining a first mapping relationship between the terminal voltage and time based on the plurality of times and the plurality of terminal voltages includes: performing a linear fit on a first function of the terminal voltage and time to determine the first mapping relationship; wherein the first function is a convergent function.

[0008] When estimating the terminal voltage, if a linear fit is made between the terminal voltage and the first function of time, the trend of the terminal voltage change over time can be obtained in a shorter time. If the first function is a convergent function, the steady-state voltage when time approaches positive infinity can be estimated more accurately.

[0009] In some embodiments, the first function is a negative power function of time.

[0010] In some embodiments, the first mapping relationship includes the terminal voltage V and the negative power of time T. -d Linear relationship: V = a * T -d +b where a is a coefficient, b is the intercept, and d is the exponential coefficient; the steady-state voltage is determined based on the terminal voltage when time approaches positive infinity according to the first mapping relationship, including: determining the steady-state voltage based on the intercept b of the linear relationship when time approaches positive infinity.

[0011] In the technical solution provided in this application embodiment, the first mapping relationship includes the terminal voltage V and the negative power of time T. -d The linear relationship between the two leads allows the model fitted by this linear relationship to predict the terminal voltage in a way that better matches the polarization elimination process. This enables a more accurate prediction of the steady-state voltage of a single battery cell, providing a more accurate SOC prediction value and thus improving the reliability of battery SOC estimation.

[0012] In some embodiments, the range of d satisfies: 0 < d ≤ 2.

[0013] The range of values ​​for d satisfies the following condition: when 0 < d ≤ 2, the error between data points in the same time interval is more appropriate, the convergence speed of the fitted terminal voltage is not too fast, and the prediction accuracy of the terminal voltage trend is higher.

[0014] During the settling phase, the rate of voltage decay is related to the conductivity of the ions. Generally, the better the conductivity of the ions, the faster the voltage decays, and the appropriate value of d varies. For example, for liquid electrolytes (lithium hexafluorophosphate, lithium perchlorate, etc.), a value of 0.1-0.5 provides high accuracy. For solid electrolytes (oxide electrolytes, sulfide electrolytes, polymer electrolytes, etc.), a value of 0.1-2 provides high accuracy.

[0015] In the technical solution provided by the embodiments of this application, the value of d within this range is not too large, which can reduce the possibility of error being amplified during the test, thereby further improving the accuracy of SOC estimation and thus improving the reliability of battery SOC estimation.

[0016] In some embodiments, the first function is the reciprocal of the natural logarithm of time.

[0017] In some embodiments, the first mapping relationship includes a linear relationship between the terminal voltage V and the reciprocal of the natural logarithm of time, 1 / ln(T): V = a * 1 / ln(T) + b, where a is a coefficient and b is the intercept; determining the steady-state voltage based on the terminal voltage when time approaches positive infinity according to the first mapping relationship includes: determining the steady-state voltage based on the intercept b of the linear relationship when time approaches positive infinity.

[0018] In some embodiments, the range of the first time period t satisfies 0.33min≤t≤30min.

[0019] In the technical solution provided in this application embodiment, the range of the first time period t satisfies 0.33min≤t≤30min. Compared with the current resting time of 3 hours or more, this greatly reduces the time required to estimate SOC, enabling SOC to be estimated in a shorter time, thereby improving the efficiency of SOC estimation.

[0020] In some embodiments, the charging or discharging rate N satisfies: 0C < N ≤ 4.0C.

[0021] In the technical solution provided in this application embodiment, by collecting the short-term terminal voltage during the resting period and using a convergence function with high accuracy to estimate the steady-state voltage, the SOC of a single battery cell can be estimated using the terminal voltage value over a shorter period of time, thereby improving the adaptability of the battery cell SOC estimation.

[0022] In some embodiments, the amount of charge or discharge Q satisfies: 0 < Q ≤ 100%.

[0023] In some embodiments, the SOC has a second mapping relationship with the steady-state voltage. Determining the SOC of a battery cell based on the steady-state voltage includes: determining the SOC of a battery cell based on the steady-state voltage and the second mapping relationship.

[0024] In some embodiments, SOC and steady-state voltage have multiple second mapping relationships, each of the multiple second mapping relationships corresponding to a single cell's SOH. The detection method further includes: acquiring the state of health (SOH) of the single cell; determining the second mapping relationship corresponding to the SOH from the multiple second mapping relationships; and determining the SOC of the single cell based on the steady-state voltage, including: determining the SOC of the single cell based on the second mapping relationship between the steady-state voltage and the corresponding SOH.

[0025] In the technical solution provided in this application embodiment, a suitable second mapping relationship is selected from multiple second mapping relationships based on the SOH of the battery cell, and the SOC of the battery cell is estimated based on the suitable second mapping relationship, thereby improving the accuracy of the battery cell SOC estimation.

[0026] In some embodiments, the second mapping relationship is determined based on a plurality of SOCs and a plurality of steady-state voltages; wherein the plurality of steady-state voltages are determined based on the terminal voltage of a single cell as time approaches positive infinity according to the first mapping relationship.

[0027] In the technical solution provided by the embodiments of this application, by sampling the terminal voltage in a short time and determining the steady-state voltage of the battery cell terminal voltage when time tends to positive infinity through the first mapping relationship, the second mapping relationship between SOC and steady-state voltage can be tested quickly, thereby improving the efficiency of SOC and steady-state voltage testing.

[0028] Secondly, a detection method is provided, comprising: acquiring multiple terminal voltages of a battery cell at multiple times within a first time period after the battery cell has been charged or discharged to one of multiple SOCs; determining a first mapping relationship between the terminal voltage and time based on the multiple times and the multiple terminal voltages, wherein the first mapping relationship converges as time approaches positive infinity; and determining a steady-state voltage corresponding to one SOC based on the terminal voltage as time approaches positive infinity according to the first mapping relationship.

[0029] In the technical solution provided by the embodiments of this application, the terminal voltage is sampled during the first time period after a battery cell is charged or discharged to one of multiple SOCs, and the steady-state voltage is determined by the terminal voltage of the battery cell when the time tends to positive infinity through the first mapping relationship. This enables the rapid acquisition of the correspondence between multiple SOCs and steady-state voltages, thereby quickly testing the second mapping relationship between SOCs and steady-state voltages, and thus improving the efficiency of SOC and steady-state voltage testing.

[0030] In some embodiments, the detection method further includes: determining a second mapping relationship between the SOC and the steady-state voltage based on the multiple stable voltages corresponding to the multiple SOCs.

[0031] In some embodiments, the detection method further includes: acquiring multiple state-of-the-art (SOH) values ​​of a single battery cell; and determining multiple second mapping relationships corresponding to the multiple SOH values.

[0032] In some embodiments, the first mapping relationship includes the terminal voltage V and the negative power of time T. -d Linear relationship: V = a * T -d +b where a is a coefficient, b is the intercept, and d is the exponential coefficient; the steady-state voltage is determined based on the terminal voltage when time approaches positive infinity according to the first mapping relationship, including: determining the steady-state voltage based on the intercept b of the linear relationship when time approaches positive infinity.

[0033] In some embodiments, the range of d satisfies: 0 < d ≤ 2.

[0034] In some embodiments, determining a first mapping relationship between the terminal voltage and time based on the plurality of times and the plurality of terminal voltages includes: performing a linear fit on a first function of the terminal voltage and time to determine the first mapping relationship; wherein the first function is a convergent function.

[0035] In some embodiments, the first function is a negative power function of time.

[0036] In some embodiments, the first mapping relationship includes a linear relationship between the terminal voltage V and the natural logarithm of time, 1 / ln(T): V = a * 1 / ln(T) + b, where a is a coefficient and b is the intercept; determining the steady-state voltage based on the terminal voltage when time approaches positive infinity according to the first mapping relationship includes: determining the steady-state voltage based on the intercept of the linear relationship when time approaches positive infinity.

[0037] In some embodiments, the range of the first time period t satisfies 0.33min≤t≤30min.

[0038] In some embodiments, the charging or discharging rate N satisfies: 0C < N ≤ 4.0C.

[0039] In some embodiments, the amount of charge or discharge Q satisfies: 0 < Q ≤ 100%.

[0040] In some embodiments, the first function is the reciprocal of the natural logarithm of time.

[0041] Thirdly, a detection apparatus is provided, comprising a memory and a processor, wherein the memory is used to store instructions and the processor is used to read the instructions and execute the detection method as described in any of the first aspects according to the instructions.

[0042] Fourthly, a detection apparatus is provided, comprising a memory and a processor, the memory for storing instructions and the processor for reading the instructions and executing the method as described in any of the second aspects.

[0043] Fifthly, an electrical device is provided, comprising: a battery cell and a detection device as described in the third aspect; wherein the battery cell is used to provide electrical energy, and the detection device is used to detect the state of charge (SOC) of the battery cell.

[0044] In a sixth aspect, a computer-readable storage medium is provided for storing a computer program that, when executed by a computer, causes the computer to implement the detection method as described in any of the first aspects, or causes the computer to implement the detection method as described in any of the second aspects.

[0045] In a seventh aspect, a computer program product is provided, comprising: computer program instructions, which, when executed by a computer, cause the computer to implement the detection method as described in any of the first aspects, or cause the computer to implement the detection method as described in any of the second aspects. Attached Figure Description

[0046] Figure 1 A schematic diagram of an electrical device according to an embodiment of this application is shown; Figure 2 A flowchart of a detection method provided in one embodiment of this application is shown; Figure 3 This paper shows a schematic diagram of the terminal voltage and resting time during the resting stage in a certain embodiment of the present application; Figure 4 A schematic diagram of a terminal voltage prediction model according to a certain embodiment of this application is shown; Figure 5 A schematic diagram of linear fitting according to a certain embodiment of this application is shown; Figure 6 This illustration shows a schematic diagram of the correspondence between predicted data and measured data in a certain embodiment of this application; Figure 7 A schematic diagram of linear fitting according to another embodiment of this application is shown; Figure 8 This illustration shows a schematic diagram of the correspondence between predicted data and measured data in another embodiment of this application; Figure 9 A flowchart of a detection method provided in another embodiment of this application is shown; Figure 10 A flowchart of a detection method provided in another embodiment of this application is shown; Figure 11 A flowchart of a detection method provided in one embodiment of this application is shown; Figure 12 This paper shows a schematic diagram of the relationship between SOC and steady-state voltage measured at different charging rates using a detection method provided in a certain embodiment of this application. Figure 13 A flowchart of a detection method provided in another embodiment of this application is shown; Figure 14 A schematic diagram of an electronic device provided in an embodiment of this application is shown. Detailed Implementation

[0047] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0048] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means two or more, unless otherwise explicitly defined. The terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing description of the drawings of this application, are intended to cover non-exclusive inclusion.

[0049] The term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Additionally, the character " / " in this text generally indicates that the preceding and following related objects have an "or" relationship.

[0050] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0051] In this application, the terms "upper," "lower," "left," "right," "inner," and "outer," indicating orientation or positional relationships, are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0052] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0053] Monitoring the State of Charge (SOC) of individual battery cells is crucial during the use or charging of electrical devices. Obtaining the SOC of a single battery cell helps users determine charging and usage time based on the remaining charge. However, current methods for estimating the SOC of individual battery cells suffer from drawbacks such as long latency and low accuracy, resulting in relatively low reliability.

[0054] Therefore, improving the reliability of single-cell SOC estimation has become an urgent problem to be solved.

[0055] This application provides a detection method for detecting the State of Charge (SOC) of a single battery cell. The detection method includes the following steps: acquiring multiple terminal voltages of the battery cell at multiple moments within a first time period after charging or discharging; determining a first mapping relationship between the terminal voltage and time based on the multiple moments and the multiple terminal voltages; wherein the first mapping relationship converges as time approaches positive infinity; determining a steady-state voltage based on the terminal voltage as time approaches positive infinity based on the first mapping relationship; and determining the SOC of the battery cell based on the steady-state voltage.

[0056] In the technical solution provided in this application, by sampling the terminal voltage at multiple moments within a first time period after a battery cell is charged or discharged, and fitting a first mapping relationship between the battery cell terminal voltage and time based on multiple pairs of time-terminal voltage data, the steady-state voltage of the battery cell can be estimated using short-time sampled data, thereby quickly obtaining the SOC of the battery cell. Simultaneously, the first mapping relationship converges at positive infinity, which improves the similarity between the estimated terminal voltage and the true value, thereby improving the accuracy of the SOC estimation and thus enhancing the reliability of the battery cell SOC estimation.

[0057] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery devices.

[0058] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical devices.

[0059] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0060] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0061] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cell assemblies housed within the housing.

[0062] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0063] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0064] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0065] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0066] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0067] In this embodiment, the battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrode plates. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the uncoated positive current collector protrudes beyond the coated positive current collector, serving as the positive electrode tab. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the uncoated negative current collector protrudes beyond the coated negative current collector, serving as the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, etc. To ensure that a large current can pass through without melting, there are multiple positive electrode tabs stacked together, and there are multiple negative electrode tabs stacked together. The separator can be made of polypropylene (PP) or polyethylene (PE), etc. Furthermore, the electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to these.

[0068] Figure 1 A schematic diagram of an electrical device according to an embodiment of this application is shown.

[0069] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0070] For example, such as Figure 1 The diagram shown is a structural schematic of a vehicle 1 according to one embodiment of this application. Vehicle 1 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A motor 40, a controller 30, and a battery device 10 can be installed inside vehicle 1. The controller 30 controls the battery device 10 to supply power to the motor 40. For example, the battery device 10 can be installed at the bottom, front, or rear of vehicle 1. The battery device 10 can be used to power vehicle 1. For example, the battery device 10 can serve as the operating power source for vehicle 1, for example, to meet the electrical system requirements of vehicle 1, such as for starting, navigation, and operation. In another embodiment of this application, the battery device 10 can not only serve as the operating power source for vehicle 1, but also as the driving power source for vehicle 1, replacing or partially replacing gasoline or natural gas to provide driving power for vehicle 1.

[0071] The following is combined with Figures 2 to 4This application describes a detection method provided in one embodiment.

[0072] Figure 2 A flowchart of a detection method provided in one embodiment of this application is shown; Figure 3 This paper shows a schematic diagram of the terminal voltage and resting time during the resting stage in a certain embodiment of the present application; Figure 4 A schematic diagram of a terminal voltage prediction model according to one embodiment of this application is shown.

[0073] This application provides a detection method for detecting the state of charge (SOC) of a single battery cell. The detection method includes the following steps.

[0074] S210: Obtain multiple terminal voltages of a battery cell at multiple times within the first time period after the battery cell has been charged or discharged.

[0075] The first period of time after charging or discharging stops is the resting phase.

[0076] As an example, a single battery cell can be charged using various charging methods, such as constant voltage charging or constant current constant voltage charging. A single battery cell can also be discharged using various discharging methods, such as normal power supply. This application does not limit the scope of these methods.

[0077] State of Charge (SOC) is usually expressed as a percentage of the remaining charge of a single battery cell.

[0078] The terminal voltage of a battery cell can be the actual potential difference between the positive and negative electrodes of the battery cell, and this application does not limit this.

[0079] Because the open-circuit voltage of a battery cell is related to the degree of lithium intercalation at its positive and negative electrodes, the state of charge (SOC) of a battery cell is usually strongly correlated with its open-circuit voltage. Therefore, the SOC of a battery cell is often estimated by measuring its open-circuit voltage. However, due to polarization during charging or discharging (such as ohmic polarization, electrochemical polarization, and concentration polarization), there is a significant error between the terminal voltage and the open-circuit voltage of a battery cell. After charging or discharging, there is still a certain difference between the terminal voltage and the open-circuit voltage of the battery cell. Therefore, in the initial period after charging or discharging, the terminal voltage of a battery cell changes dynamically over time. Thus, it is not possible to directly correlate the SOC of a battery cell by simply measuring its terminal voltage.

[0080] S220 determines the first mapping relationship between terminal voltage and time based on multiple times and multiple terminal voltages.

[0081] The first mapping converges as time approaches positive infinity.

[0082] The system acquires the terminal voltage of each battery cell at multiple time points and the corresponding terminal voltages at those times. Based on these multiple time points and their corresponding terminal voltages, a first mapping relationship reflecting the change of terminal voltage over time can be fitted. This first mapping relationship allows for the estimation of the terminal voltage at times following a first time period.

[0083] S230, determine the steady-state voltage based on the terminal voltage when time approaches positive infinity according to the first mapping relationship.

[0084] The first mapping relationship corresponds to the steady-state voltage of a single battery cell when time approaches positive infinity. That is, the first mapping relationship converges when time approaches positive infinity; otherwise, it cannot obtain a value when time approaches positive infinity. For example... Figure 3 As shown, the model prediction curve gradually flattens out over time, and the terminal voltage gradually approaches the steady-state voltage.

[0085] Steady-state voltage is the open-circuit voltage that a battery cell maintains after being left to stand for a sufficient period of time. During charging or discharging, polarization such as ohmic polarization, electrochemical polarization, and concentration polarization can cause significant discrepancies between the terminal voltage and the open-circuit voltage of a battery cell. Therefore, it is necessary to eliminate the effects of ohmic polarization, electrochemical polarization, and concentration polarization to obtain the steady-state voltage and thus accurately estimate the state of charge (SOC) of the battery cell.

[0086] The usual practice is to stop charging and discharging and let the battery cells rest to allow the polarization phenomenon inside the cells to subside. However, this process often lasts for several hours. By using the first mapping relationship that converges when time approaches positive infinity to reflect the relationship between the battery cell terminal voltage and time, the resting time of the battery cells can be shortened, so that the SOC estimation of the battery cells can be performed in real time and accurately during the charging and discharging process.

[0087] S240 determines the SOC of a single battery cell based on the steady-state voltage.

[0088] In the technical solution provided in this application, by sampling the terminal voltage at multiple moments within a first time period after a battery cell is charged or discharged, and fitting a first mapping relationship between the battery cell terminal voltage and time based on multiple pairs of time-terminal voltage data, the steady-state voltage of the battery cell can be estimated using short-time sampled data, thereby quickly obtaining the SOC of the battery cell. Simultaneously, the first mapping relationship converges at positive infinity, which improves the similarity between the estimated terminal voltage and the true value, thereby improving the accuracy of the SOC estimation and thus enhancing the reliability of the battery cell SOC estimation.

[0089] In some possible embodiments, determining the first mapping relationship between terminal voltage and time based on multiple moments and multiple terminal voltages can be achieved by linearly fitting a first function of terminal voltage and time to determine the first mapping relationship; wherein the first function is a convergent function.

[0090] The first function being a convergent function can be understood as having real values ​​when time is positive infinity, such as e^-T, 1 / ln(T), T^-0.1, etc. The embodiments of this application are not limited to this.

[0091] When estimating the terminal voltage, if a linear fit is made between the terminal voltage and the first function of time, the trend of the terminal voltage change over time can be obtained in a shorter time. If the first function is a convergent function, the steady-state voltage when time approaches positive infinity can be estimated more accurately.

[0092] In some possible implementations, the first mapping converges when time is infinite.

[0093] That is, there exists a corresponding terminal voltage value when time is positive infinity.

[0094] When time is infinite, the first mapping relationship that converges can be, for example, a negative power function, an inverse proportional function, a negative exponential function, etc., but the embodiments of this application are not limited thereto.

[0095] Combination Figures 5 to 7 This application describes a detection method provided in one embodiment.

[0096] Figure 5 A schematic diagram of linear fitting according to a certain embodiment of this application is shown; Figure 6 A schematic diagram showing the correspondence between predicted data and measured data in one embodiment of this application is shown.

[0097] In some possible embodiments, the first function is a negative power function of time.

[0098] The difference between the terminal voltage and steady-state voltage of a single battery cell is caused by factors such as polarization within the cell. Polarization phenomena, such as concentration polarization, satisfy a diffusion model after the current generated by polarization ceases. The change in ion concentration at the cell electrode, ΔC, is related to... Relatedly, the potential difference caused by concentration polarization is concentration-dependent and satisfies E = f * ln(C1 / C2), where E is the concentration polarization potential difference, f is a constant, C1 is the ion concentration at the positive electrode, and C2 is the ion concentration at the negative electrode. Therefore, the first mapping relationship includes the terminal voltage V and the negative power of time T. -d The linear relationship can better simulate the trend of polarization, making the simulation of the terminal voltage more consistent with the real terminal voltage value.

[0099] In some possible embodiments, the first mapping relationship includes the terminal voltage V and the negative power of time T. -d Linear relationship: V=a*T -d +b; Where a is the coefficient, b is the intercept, and d is the exponential coefficient.

[0100] By performing a linear fit on multiple time points and multiple terminal voltages according to the above formula, we obtain the following: Figure 5 The linear relationship shown. Figure 5 For example, d is taken as 0.1, but this application is not limited to this.

[0101] As time approaches positive infinity, the coefficient term approaches 0, so the steady-state voltage can be determined directly from the intercept b of the linear relationship.

[0102] For example, such as Figure 6 As shown, when d is 0.1, the predicted and measured values ​​of the terminal voltage have good consistency over the entire time line.

[0103] In the technical solution provided in this application embodiment, the first mapping relationship includes the terminal voltage V and the negative power of time T. -d The linear relationship between the two leads allows the model fitted by this linear relationship to predict the terminal voltage in a way that better matches the polarization elimination process. This enables a more accurate prediction of the steady-state voltage of a single battery cell, providing a more accurate SOC prediction value and thus improving the reliability of battery SOC estimation.

[0104] In some possible embodiments, the range of d satisfies: 0 < d ≤ 2.

[0105] The range of values ​​for d satisfies the following condition: when 0 < d ≤ 2, the error between data points in the same time interval is more appropriate, the convergence speed of the fitted terminal voltage is not too fast, and the prediction accuracy of the terminal voltage trend is higher.

[0106] During the settling phase, the rate of voltage decay is related to the conductivity of the ions. Generally, the better the conductivity of the ions, the faster the voltage decays, and the appropriate value of d varies. For example, for liquid electrolytes (lithium hexafluorophosphate, lithium perchlorate, etc.), a value of 0.1-0.5 provides high accuracy. For solid electrolytes (oxide electrolytes, sulfide electrolytes, polymer electrolytes, etc.), a value of 0.1-2 provides high accuracy.

[0107] In this embodiment, the accuracy can be compared with the estimated steady-state voltage and the steady-state voltage after resting for more than 3 hours. The ratio of the difference between the two to the steady-state voltage after resting for more than 3 hours is less than 1%, which can be considered as high accuracy.

[0108] In the technical solution provided by the embodiments of this application, the value of d within this range is not too large, which can reduce the possibility of error being amplified during the test, thereby further improving the accuracy of SOC estimation and thus improving the reliability of battery SOC estimation.

[0109] In some embodiments, the range of d satisfies 0.05 ≤ d ≤ 1. When d is within this range, on the one hand, the lower limit of d is increased, making the differences in values ​​during the detection process more significant, and the downward trend of the fitted curve is not too gradual. This reduces the amount of data required to obtain an accurate trend, allowing for the fitting of a more accurate model in a shorter time, thus accelerating the testing process. On the other hand, it further reduces the possibility of error amplification during testing, thereby further improving the accuracy of SOC estimation and consequently enhancing the reliability of battery SOC estimation.

[0110] In some embodiments, the value of d can also be other values. For example, d can take any of the following values ​​or any value between any two values: 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0.

[0111] Combination Figure 7 and Figure 8 This application describes a detection method provided in another embodiment.

[0112] Figure 7 A schematic diagram of linear fitting according to another embodiment of this application is shown; Figure 8 A schematic diagram showing the correspondence between predicted data and measured data in another embodiment of this application is shown.

[0113] In some possible embodiments, the first function is the reciprocal of the natural logarithm of time.

[0114] In some possible embodiments, the first mapping relationship includes a linear relationship between the terminal voltage V and the reciprocal of the natural logarithm of time, 1 / ln(T): V = a * 1 / ln(T) + b; Where a is the coefficient and b is the intercept.

[0115] As time approaches positive infinity, the steady-state voltage is determined based on the intercept b of the linear relationship.

[0116] In some possible embodiments, the range of the first time period t satisfies 0.33min≤t≤30min.

[0117] To obtain an accurate steady-state voltage, it is currently often necessary to let the battery stand for more than 3 hours. However, for electrical devices such as vehicles, letting the battery stand for 3 hours during charging and use has significant limitations on charging and use. Therefore, it is currently difficult to accurately obtain the SOC of a single battery cell in a short period of time.

[0118] The detection method provided in this application uses a function that conforms to the characteristics of the battery electrolyte to fit the relationship between the terminal voltage and time. This function converges when time is infinite. Only 20s (i.e. 0.33min) or more of test data is needed to predict a more accurate steady-state voltage, thereby enabling a more accurate estimation of the SOC.

[0119] In the technical solution provided in this application embodiment, the range of the first time period t satisfies 0.33min≤t≤30min. Compared with the current resting time of 3 hours or more, this greatly reduces the time required to estimate SOC, enabling SOC to be estimated in a shorter time, thereby improving the efficiency of SOC estimation.

[0120] In some embodiments, the range of the first time period t satisfies 0.5 min ≤ t ≤ 5 min. When t is within this range, on the one hand, the lower limit of the first time period is increased, allowing for the collection of more terminal voltage data and improving the accuracy of steady-state voltage prediction. On the other hand, the range of the first time period can be smaller, thus making it applicable to more charging and discharging scenarios, thereby improving the reliability of battery SOC estimation.

[0121] In some embodiments, t can also be other values. For example, d can take any of the following values ​​or any value between any two values: 0.33 min, 0.5 min, 1 min, 1.5 min, 3.0 min, 4.5 min, 6.0 min, 7.5 min, 9.0 min, 10.5 min, 12.0 min, 13.5 min, 15.0 min, 16.5 min, 18.0 min, 19.5 min, 21.0 min, 22.5 min, 24.0 min, 25.5 min, 27.0 min, 28.5 min, and 30 min.

[0122] In some possible embodiments, the charging or discharging rate N satisfies: 0C < N ≤ 4.0C.

[0123] To obtain an accurate steady-state voltage, a small current charging and discharging method is often used to reduce the impact of polarization on the terminal voltage. However, this method limits the efficiency of charging and use, and even with a small current charging and discharging method, the impact of polarization on the terminal voltage cannot be eliminated.

[0124] In the technical solution provided in this application, by collecting the short-term terminal voltage during the resting phase and estimating the steady-state voltage using a convergence function with high accuracy, the SOC of a single battery cell can be estimated using the terminal voltage value over a shorter period, thereby improving the adaptability of the battery cell SOC estimation. On the other hand, the charging rate is not too high, thus protecting the performance of the power battery from being affected.

[0125] In some embodiments, the charging or discharging rate N satisfies: 0.04C ≤ N ≤ 1.5C. When N is within this range, on the one hand, polarization has a smaller impact on the terminal voltage of the battery cell, leading to more accurate prediction of the steady-state voltage of the battery cell. On the other hand, a lower upper limit for the charging or discharging rate reduces the possibility that factors such as lithium plating in the battery cell will affect the SOC prediction, thereby improving the reliability of the battery SOC estimation.

[0126] In some embodiments, N can also take other values. For example, N can take any of the following values ​​or any value between any two values: 0.04C, 0.1C, 0.2C, 0.4C, 0.5C, 0.6C, 0.8C, 1.0C, 1.2C, 1.4C, 1.5C, 1.6C, 1.8C, 2.0C, 2.2C, 2.4C, 2.6C, 2.8C, 3.0C, 3.2C, 3.4C, 3.6C, 3.8C, and 4.0C.

[0127] In some possible embodiments, the amount of charge or discharge Q satisfies: 0 < Q ≤ 100%.

[0128] A smaller single charge / discharge capacity can meet the requirements of higher precision, while a larger single charge / discharge capacity can meet the application needs of more scenarios.

[0129] Figure 9 A flowchart of a detection method provided in another embodiment of this application is shown; Figure 10 A flowchart of a detection method provided in another embodiment of this application is shown.

[0130] In some possible embodiments, the SOC has a second mapping relationship with the steady-state voltage. Determining the SOC of a single battery cell based on the steady-state voltage includes the following steps: S241, determine the SOC of the battery cell based on the steady-state voltage and the second mapping relationship.

[0131] The second mapping relationship is the mapping relationship between SOC and steady-state voltage or open-circuit voltage.

[0132] After obtaining an accurate steady-state voltage through the above embodiments, the SOC of a single battery cell can be determined through the second mapping relationship.

[0133] In some possible embodiments, SOC and steady-state voltage have multiple second mapping relationships, each of which corresponds to a state of health (SOH) of a battery cell.

[0134] The state of harmonics (SOH) of a battery cell reflects the degree of performance degradation caused by aging. The mapping relationship between state of charge (SOC) and steady-state voltage (SVT) differs under different SOH values. Therefore, by obtaining the current SOH of a battery cell, a different secondary mapping relationship can be selected based on the current SOH.

[0135] S250, obtain the SOH of the battery cell.

[0136] The method for obtaining SOH can be determined based on the cycle number of a single battery cell, or it can be detected by other means. This application does not limit this method.

[0137] For example, although general battery testing methods use the number of charge-discharge cycles as the basis for determining SOH (State of Health), different users have different habits when using electrical devices, which may lead to different aging trajectories of the batteries in the devices. Therefore, other testing methods can be used, such as recalibrating the SOH using the testing method provided in the above embodiments of this application. Specifically, the testing method provided in the embodiments of this application is used to quickly determine multiple steady-state voltages and the SOC (State of Charge) corresponding to these multiple steady-state voltages. Based on the multiple steady-state voltages and the SOC corresponding to these multiple steady-state voltages, the second mapping relationship satisfied by the current battery device is determined from multiple second mapping relationships, and the SOH corresponding to the second mapping relationship is determined.

[0138] S260, determine the second mapping relationship corresponding to SOH from multiple second mapping relationships.

[0139] Determining the second mapping relationship corresponding to SOH from multiple second mapping relationships can be done by selecting the second mapping relationship according to a preset correspondence relationship. This application embodiment does not limit this.

[0140] Determining the SOC of a single battery cell based on the steady-state voltage can be achieved through the following steps: S270 determines the SOC of a single cell based on the second mapping relationship between the steady-state voltage and the corresponding SOH.

[0141] In the technical solution provided in this application embodiment, a suitable second mapping relationship is selected from multiple second mapping relationships based on the SOH of the battery cell, and the SOC of the battery cell is estimated based on the suitable second mapping relationship, thereby improving the accuracy of the battery cell SOC estimation.

[0142] In some possible embodiments, the second mapping relationship is determined based on multiple SOCs and multiple steady-state voltages; wherein the multiple steady-state voltages are determined based on the terminal voltage of a single cell as time approaches positive infinity according to the first mapping relationship.

[0143] When determining the mapping relationship between SOC and steady-state voltage, it is necessary to collect steady-state voltage values ​​under multiple SOC states. If the method of letting the battery cell stand still for several hours is adopted, it will take too long to obtain the mapping relationship between SOC and steady-state voltage. However, by using the steady-state voltage prediction method provided in this application embodiment to test and obtain the mapping relationship between SOC and steady-state voltage, it can take less time, thereby improving the testing efficiency.

[0144] In the technical solution provided by the embodiments of this application, by sampling the terminal voltage in a short time and determining the steady-state voltage of the battery cell terminal voltage when time tends to positive infinity through the first mapping relationship, the second mapping relationship between SOC and steady-state voltage can be tested quickly, thereby improving the efficiency of SOC and steady-state voltage testing.

[0145] Figure 11 A flowchart of a detection method provided in one embodiment of this application is shown; Figure 12 This paper shows a schematic diagram of the relationship between SOC and steady-state voltage measured at different charging rates using a detection method provided in a certain embodiment of this application. Figure 13 A flowchart of a detection method provided in another embodiment of this application is shown.

[0146] This application provides a detection method, which includes the following steps: S310: Obtain multiple terminal voltages of a battery cell at multiple times within a first time period after the battery cell has been charged or discharged to one of multiple SOCs.

[0147] The SOC of a single battery cell can be, for example, 5%, 10%, 15%, 30%, 50%, 100%, etc., and this application does not limit this.

[0148] For example, charging or discharging to one of a plurality of SOCs could be, for instance, charging or discharging to 50%.

[0149] S320 determines the first mapping relationship between terminal voltage and time based on multiple times and multiple terminal voltages.

[0150] The first mapping converges as time approaches positive infinity.

[0151] The system acquires the terminal voltage of each battery cell at multiple time points and the corresponding terminal voltages at those times. Based on these multiple time points and their corresponding terminal voltages, a first mapping relationship reflecting the change of terminal voltage over time can be fitted. This first mapping relationship allows for the estimation of the terminal voltage at times following a first time period.

[0152] S330 determines the steady-state voltage corresponding to a SOC based on the terminal voltage when time approaches positive infinity according to the first mapping relationship.

[0153] In some possible embodiments, determining the first mapping relationship between terminal voltage and time based on multiple moments and multiple terminal voltages can be achieved by linearly fitting a first function of terminal voltage and time to determine the first mapping relationship; wherein the first function is a convergent function.

[0154] The first function being a convergent function can be understood as having real values ​​when time is positive infinity, such as e^-T, 1 / ln(T), T^-0.1, etc. The embodiments of this application are not limited to this.

[0155] When estimating the terminal voltage, if a linear fit is made between the terminal voltage and the first function of time, the trend of the terminal voltage change over time can be obtained in a shorter time. If the first function is a convergent function, the steady-state voltage when time approaches positive infinity can be estimated more accurately.

[0156] Combination Figure 12 It can be seen that the test results of this detection method are consistent under various charging rates, indicating that the steady-state voltage value predicted by this method is close to the actual true value, and the reliability of this detection method is good.

[0157] In the technical solution provided by the embodiments of this application, the terminal voltage is sampled during the first time period after a battery cell is charged or discharged to one of multiple SOCs, and the steady-state voltage is determined by the terminal voltage of the battery cell when the time tends to positive infinity through the first mapping relationship. This enables the rapid acquisition of the correspondence between multiple SOCs and steady-state voltages, thereby quickly testing the second mapping relationship between SOCs and steady-state voltages, and thus improving the efficiency of SOC and steady-state voltage testing.

[0158] In some possible embodiments, the detection method further includes determining a second mapping relationship between the SOC and the steady-state voltage based on the multiple stable voltages corresponding to the multiple SOCs.

[0159] In some possible embodiments, the detection method further includes: S350, obtains multiple SOHs of individual battery cells.

[0160] S360, determine multiple second mapping relationships corresponding to multiple SOHs.

[0161] In some possible embodiments, the first function is a negative power function of time.

[0162] In some possible embodiments, the first mapping relationship includes the terminal voltage V and the negative power of time T. -d Linear relationship: V=a*T -d +b Where a is the coefficient, b is the intercept, and d is the exponential coefficient; Determining the steady-state voltage based on the terminal voltage as time approaches positive infinity according to the first mapping relationship includes: As time approaches positive infinity, the steady-state voltage is determined based on the intercept b of the linear relationship.

[0163] In some possible embodiments, the range of d satisfies: 0 < d ≤ 2.

[0164] In some possible embodiments, the first function is the reciprocal of the natural logarithm of time.

[0165] In some possible embodiments, the first mapping relationship includes a linear relationship between the terminal voltage V and the reciprocal of the natural logarithm of time, 1 / ln(T): V = a * 1 / ln(T) + b Where a is the coefficient and b is the intercept; Determining the steady-state voltage based on the terminal voltage as time approaches positive infinity according to the first mapping relationship includes: determining the steady-state voltage based on the intercept of the linear relationship as time approaches positive infinity.

[0166] In some possible embodiments, the range of the first time period t satisfies 0.33min≤t≤30min.

[0167] In some possible embodiments, the charging or discharging rate N satisfies: 0C < N ≤ 4.0C.

[0168] In some possible embodiments, the amount of charge or discharge Q satisfies: 0 < Q ≤ 100%.

[0169] The technical effects of the above embodiments can be found in the preceding text, and will not be elaborated further here.

[0170] Figure 14 A schematic diagram of an electronic device provided in an embodiment of this application is shown.

[0171] The electronic device 1000 can be a detection device, which includes a memory 1010 and a processor 1020. The memory 1010 is used to store instructions, and the processor 1020 is used to read instructions and execute the detection method in the above embodiments according to the instructions.

[0172] The electronic device 1000 can be a detection device, which includes a memory 1010 and a processor 1020. The memory 1010 is used to store instructions, and the processor 1020 is used to read instructions and execute the detection method in the above embodiments according to the instructions.

[0173] The memory 1010 can be a separate device independent of the processor 1020, or it can be integrated into the processor 1020.

[0174] It should be understood that the processor 1020 in this application embodiment may be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above method embodiments can be completed by the integrated logic circuitry in the hardware of the processor 1020 or by instructions in software form. The processor 1020 may be a general-purpose processor, 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, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules may be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in memory, and the processor reads information from the memory and combines it with its hardware to complete the steps of the above method.

[0175] It is understood that the memory 1010 in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory 1010 of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory 1010.

[0176] Optionally, embodiments of this application also provide an electrical device, which includes a battery cell and a detection device provided in embodiments of this application.

[0177] This application also provides a computer-readable storage medium for storing computer programs.

[0178] Optionally, the computer-readable storage medium can be applied to the detection device in the embodiments of this application, and when the computer program is run on the computer, it causes the computer to execute the corresponding processes implemented by the detection device in the various methods of the embodiments of this application. For the sake of brevity, it will not be described in detail here.

[0179] This application also provides a computer program product, including computer program instructions.

[0180] Optionally, the computer program product can be applied to the detection device in the embodiments of this application, and the computer program instructions, when run on a computer, cause the computer to execute the corresponding processes implemented by the detection device in the various methods of the embodiments of this application. For the sake of brevity, they will not be described in detail here.

[0181] This application also provides a computer program.

[0182] Optionally, the computer program can be applied to the detection device in the embodiments of this application. When the computer program is run on a computer, it causes the computer to execute the corresponding processes implemented by the detection device in the various methods of the embodiments of this application. For the sake of brevity, it will not be described in detail here.

[0183] 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.

[0184] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0185] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of 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. In addition, the mutual coupling or direct coupling or communication connection involved in the embodiments of this application may be through some interfaces, and the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms.

[0186] 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.

[0187] In addition, the functional units in the various embodiments of this application 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.

[0188] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0189] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A detection method, characterized in that, The detection method is used to detect the state of charge (SOC) of a single battery cell, and the detection method includes: Obtain multiple terminal voltages of the battery cell at multiple times within a first time period after the battery cell has been charged or discharged; A first mapping relationship between the terminal voltage and time is determined based on the plurality of time points and the plurality of terminal voltages, wherein the first mapping relationship converges as time approaches positive infinity; The steady-state voltage is determined based on the terminal voltage when time approaches positive infinity according to the first mapping relationship; The SOC of the battery cell is determined based on the steady-state voltage.

2. The detection method according to claim 1, characterized in that, Determining the first mapping relationship between the terminal voltage and time based on the plurality of times and the plurality of terminal voltages includes: A linear fit is performed on a first function of terminal voltage and time to determine the first mapping relationship; The first function is a convergent function.

3. The detection method according to claim 2, characterized in that, The first function is a negative power function of time.

4. The detection method according to claim 3, characterized in that, The first mapping relationship includes the terminal voltage V and the negative power of time T. -d Linear relationship: V=a*T -d +b Where a is the coefficient, b is the intercept, and d is the exponential coefficient; The step of determining the steady-state voltage based on the terminal voltage when time approaches positive infinity according to the first mapping relationship includes: As time approaches positive infinity, the steady-state voltage is determined based on the intercept b of the linear relationship.

5. The detection method according to claim 4, characterized in that, The range of d satisfies: 0 < d ≤ 2.

6. The detection method according to claim 2, characterized in that, The first function is the reciprocal of the natural logarithm of time.

7. The detection method according to claim 6, characterized in that, The first mapping relationship includes a linear relationship between the terminal voltage V and the reciprocal of the natural logarithm of time, 1 / ln(T): V = a * 1 / ln(T) + b Where a is the coefficient and b is the intercept; The step of determining the steady-state voltage based on the terminal voltage when time approaches positive infinity according to the first mapping relationship includes: As time approaches positive infinity, the steady-state voltage is determined based on the intercept b of the linear relationship.

8. The detection method according to any one of claims 1 to 7, characterized in that, The range of the first time period t satisfies 0.33min≤t≤30min.

9. The detection method according to any one of claims 1 to 7, characterized in that, The charging or discharging rate N satisfies: 0C < N ≤ 4.0C.

10. The detection method according to any one of claims 1 to 7, characterized in that, The charge or discharge quantity Q satisfies: 0 < Q ≤ 100%.

11. The detection method according to any one of claims 1 to 7, characterized in that, The SOC and the steady-state voltage have a second mapping relationship, and determining the SOC of the battery cell based on the steady-state voltage includes: The SOC of the battery cell is determined based on the steady-state voltage and the second mapping relationship.

12. The detection method according to claim 11, characterized in that, The SOC and the steady-state voltage have multiple second mapping relationships, each of the multiple second mapping relationships corresponding to a SOH of the battery cell, and the detection method further includes: Obtain the SOH of the battery cell; Determine the second mapping relationship corresponding to the SOH from the plurality of second mapping relationships; Determining the SOC of the battery cell based on the steady-state voltage includes: The SOC of the battery cell is determined based on the steady-state voltage and the second mapping relationship corresponding to the SOH.

13. The detection method according to claim 11, characterized in that, The second mapping relationship is determined based on multiple SOCs and multiple steady-state voltages; The plurality of steady-state voltages are determined based on the terminal voltage of the battery cell as time approaches positive infinity, according to the first mapping relationship.

14. A detection method, characterized in that, include: The battery cell is charged or discharged to one of a plurality of SOCs and the battery cell is charged or discharged to a certain SOC. The battery cell is charged or discharged to a certain SOC and the battery cell is .... The battery cell is discharged to a certain SOC. The battery cell is discharged to a certain SOC. The battery cell is discharged to a certain SOC. The battery cell A first mapping relationship between the terminal voltage and time is determined based on the plurality of time points and the plurality of terminal voltages, wherein the first mapping relationship converges as time approaches positive infinity; The steady-state voltage corresponding to the SOC is determined based on the terminal voltage when time approaches positive infinity according to the first mapping relationship.

15. The detection method according to claim 14, characterized in that, The detection method further includes: A second mapping relationship between SOC and steady-state voltage is determined based on multiple stable voltages corresponding to multiple SOCs.

16. The detection method according to claim 15, characterized in that, The detection method further includes: Obtain multiple SOHs of individual battery cells; Determine a plurality of the second mapping relationships corresponding to the plurality of SOHs.

17. The detection method according to any one of claims 14 to 16, characterized in that, Determining the first mapping relationship between the terminal voltage and time based on the plurality of times and the plurality of terminal voltages includes: A linear fit is performed on a first function of terminal voltage and time to determine the first mapping relationship; The first function is a convergent function.

18. The detection method according to claim 17, characterized in that, The first function is a negative power function of time.

19. The detection method according to claim 18, characterized in that, The first mapping relationship includes the terminal voltage V and the negative power of time t. -d Linear relationship: V=a*T -d +b Where a is the coefficient, b is the intercept, and d is the exponential coefficient; The step of determining the steady-state voltage based on the terminal voltage when time approaches positive infinity according to the first mapping relationship includes: As time approaches positive infinity, the steady-state voltage is determined based on the intercept b of the linear relationship.

20. The detection method according to claim 19, characterized in that, The range of d satisfies: 0 < d ≤ 2.

21. The detection method according to claim 17, characterized in that, The first function is the reciprocal of the natural logarithm of time.

22. The detection method according to claim 21, characterized in that, The first mapping relationship includes a linear relationship between the terminal voltage V and 1 / ln(T), which is one-third of the natural logarithm of time: V = a * 1 / ln(T) + b Where a is the coefficient and b is the intercept; The step of determining the steady-state voltage based on the terminal voltage when time approaches positive infinity according to the first mapping relationship includes: As time approaches positive infinity, the steady-state voltage is determined based on the intercept of the linear relationship.

23. A detection device, characterized in that, The detection device includes a memory and a processor. The memory is used to store instructions, and the processor is used to read the instructions and execute the detection method as described in any one of claims 1 to 13 according to the instructions.

24. A detection device, characterized in that, The detection device includes a memory and a processor. The memory is used to store instructions, and the processor is used to read the instructions and execute the detection method as described in any one of claims 14 to 22 according to the instructions.

25. An electrical appliance, characterized in that, The electrical device includes: Battery cell and the detection device as described in claim 23; The battery cell is used to provide electrical energy, and the detection device is used to detect the state of charge (SOC) of the battery cell.

26. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store a computer program, which, when executed by a computer, causes the computer to implement the detection method as described in any one of claims 1 to 13, or causes the computer to implement the detection method as described in any one of claims 14 to 22.

27. A computer program product, characterized in that, include: Computer program instructions, when executed by a computer, cause the computer to implement the detection method as described in any one of claims 1 to 13, or cause the computer to implement the detection method as described in any one of claims 14 to 22.

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