Method, device and equipment for generating soc-ocv curve of battery

Abstract

The application is suitable for the technical field of batteries, and provides a SOC-OCV curve generation method, device and equipment of a battery. The method comprises the following steps: obtaining a battery voltage and a battery SOC of the battery; when the battery SOC is located in a platform interval, calculating an equivalent open circuit voltage value of the battery according to the battery voltage and a preset equivalent circuit model; when the battery SOC is located in a non-platform interval, performing correction processing on the battery voltage according to a battery current to obtain the equivalent open circuit voltage value of the battery; and combining the battery SOC and the equivalent open circuit voltage value to draw an SOC-OCV curve of the battery. According to the scheme, the equivalent open circuit voltage value of the battery is calculated by using different calculation methods in different battery SOC intervals, so that the battery characteristics of the platform interval and the non-platform interval can be fully considered and combined, and the calculated equivalent open circuit voltage value is more accurate.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method, apparatus, and device for generating the SOC-OCV curve of a battery. Background Technology

[0002] With the increasing popularity of electronic applications such as mobile electronic devices, electric vehicles, and new energy storage systems, users are paying more and more attention to the accurate estimation of battery state of charge.

[0003] The State of Charge (SOC) of a battery is one of the important parameters of a battery management system. By monitoring and controlling the battery SOC, the charging and discharging of the battery can be systematically managed, ensuring the safe, stable, and long-life operation of the battery. Because there is a one-to-one correspondence between the battery's open circuit voltage (OCV) and its SOC, OCV is an important calibration parameter in the process of estimating the battery's SOC.

[0004] In relevant schemes, electrochemical models and equivalent circuit models are mainly used to estimate the mapping relationship between dynamic SOC and OCV. Electrochemical models have high accuracy, but they require a large amount of experimental data and the calculation process is very complicated, making them difficult to promote and use. Equivalent circuit models are simple and easy to understand, but their accuracy is poor and cannot meet users' expectations. Summary of the Invention

[0005] This application provides a method, apparatus, and device for generating the SOC-OCV curve of a battery, which can efficiently and accurately estimate and plot the SOC-OCV curve of a battery.

[0006] In a first aspect, embodiments of this application provide a method for generating the SOC-OCV curve of a battery, including:

[0007] Obtain the battery voltage and battery SOC.

[0008] When the battery SOC is in the plateau range, the equivalent open-circuit voltage of the battery is calculated based on the battery voltage and the preset equivalent circuit model.

[0009] When the battery SOC is in the non-plateau range, the battery voltage is corrected based on the battery current to obtain the battery's equivalent open-circuit voltage value.

[0010] Plot the SOC-OCV curve of the battery by combining the battery's SOC and equivalent open-circuit voltage.

[0011] Secondly, embodiments of this application provide a battery SOC-OCV curve generation apparatus, which has the function of implementing the method in the first aspect or any possible implementation thereof. Specifically, the apparatus includes units for implementing the method in the first aspect or any possible implementation thereof.

[0012] In one embodiment, the device includes:

[0013] The acquisition unit is used to acquire the battery voltage and battery SOC.

[0014] The processing unit is used to calculate the equivalent open-circuit voltage of the battery based on the battery voltage and a preset equivalent circuit model when the battery SOC is in the plateau range.

[0015] The processing unit is also used to correct the battery voltage based on the battery current when the battery SOC is in the non-plateau range, so as to obtain the equivalent open circuit voltage value of the battery.

[0016] The processing unit is also used to plot the SOC-OCV curve of the battery by combining the battery SOC and the equivalent open-circuit voltage value.

[0017] Thirdly, embodiments of this application provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it causes the computer device to implement any of the implementation methods of the first aspect described above.

[0018] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program, which, when executed by a computer device, causes the computer device to implement any of the implementation methods of the first aspect described above.

[0019] Fifthly, embodiments of this application provide a computer program product that, when run on a computer device, causes the computer device to execute any of the implementation methods of the first aspect described above.

[0020] The beneficial effects of this application embodiment compared with the prior art are as follows: By collecting battery voltage and battery SOC as data sources, a comprehensive analysis of the relationship between voltage and SOC during battery charging or discharging can be performed, improving the reliability of the calculation results; the specific condition of the battery in a non-static state is determined according to the distribution range of battery SOC, and calculations are performed separately for different battery SOC ranges. That is, in the plateau range, the equivalent open-circuit voltage value of the battery is calculated using a preset equivalent circuit model. This method can more accurately describe the actual working principle of the battery, and the calculated equivalent open-circuit voltage value is more accurate; in the non-plateau range, the battery voltage is corrected using battery current, which can reduce the measurement error caused by large battery voltage fluctuations, thereby improving the accuracy of the calculated equivalent open-circuit voltage value. In other words, using different calculation methods to calculate the equivalent open-circuit voltage value of the battery in different battery SOC ranges can fully consider and combine the battery characteristics in the plateau and non-plateau ranges, resulting in a more accurate equivalent open-circuit voltage value. As a result, the dispersion of the battery's SOC-OCV curve is smaller, and it is closer to the real SOC-OCV curve, improving the accuracy of the battery SOC-OCV curve. Attached Figure Description

[0021] Figure 1 It is a comparison chart of the battery voltage and SOC data collected directly in the non-static state with the standard SOC-OCV curve of the battery.

[0022] Figure 2 This is a flowchart illustrating a method for generating the SOC-OCV curve of a battery according to an embodiment of this application.

[0023] Figure 3 This is an SOC-OCV curve of a certain type of battery provided in an embodiment of this application.

[0024] Figure 4 This is an SOC-OCV curve of a certain type of battery obtained by using the SOC-OCV curve generation method of the present application in one embodiment of the present application.

[0025] Figure 5 This is a schematic flowchart illustrating a process for calculating the equivalent open-circuit voltage when the battery's state of charge (SOC) is in the non-plateau range, as provided in an embodiment of this application.

[0026] Figure 6 This is a circuit diagram of a second-order equivalent circuit model provided in an embodiment of this application.

[0027] Figure 7 This is a schematic diagram of an HPPC voltage response curve provided in an embodiment of this application.

[0028] Figure 8This is a schematic diagram of the device provided in the embodiments of this application.

[0029] Figure 9 This is a schematic diagram of the structure of the computer device provided in the embodiments of this application. Detailed Implementation

[0030] When the battery is not in a static state, the Battery Management System (BMS) can collect data corresponding to the battery's State of Charge (SOC) and Open Value (OCV) by monitoring the battery's charging and discharging process, and then use this collected data to plot the SOC-OCV curve. Typically, the relationship between battery SOC and battery OCV is non-linear, meaning that the battery OCV will change differently at different battery SOCs.

[0031] The SOC-OCV curve can be used to determine the state of charge of a battery, thus helping users understand the remaining capacity of the battery. At the same time, the SOC-OCV curve can also be used to calibrate the SOC estimation algorithm in the BMS, thereby improving the reliability and lifespan of the battery. Therefore, an accurate SOC-OCV curve is of great significance for the normal use of the battery.

[0032] The following is combined with Figure 1 Let's take a closer look at the SOC-OCV curve of a certain type of battery.

[0033] Figure 1 It is a comparison chart of the battery voltage and SOC data collected directly in the non-static state with the standard SOC-OCV curve of the battery.

[0034] like Figure 1 As shown, Figure 1 The curve formed by connecting the black data points represents the actual standard SOC-OCV curve of the battery, while the white data points represent the battery OCV collected in real time by the BMS under different battery SOC states. It is evident that the SOC-OCV relationship obtained by directly collecting battery SOC and OCV without modification has a significant error compared to the actual SOC-OCV curve, failing to meet users' needs for obtaining the actual remaining battery capacity.

[0035] To address the aforementioned issues, this application proposes a method for generating the SOC-OCV curve of a battery. By employing different methods to calculate the equivalent open-circuit voltage value of the battery in different SOC ranges, the equivalent open-circuit voltage value obtained under different battery SOC states is more accurate, thereby yielding a more accurate SOC-OCV curve.

[0036] To further illustrate the technical solution of this application, specific embodiments are described below.

[0037] Figure 2 This is a flowchart illustrating a method for generating the SOC-OCV curve of a battery according to an embodiment of this application.

[0038] like Figure 2 As shown, the above method includes the following steps S201 to S204.

[0039] S201. Obtain the battery voltage and battery SOC.

[0040] Battery voltage refers to the voltage value measured when the battery is not in a static state; it can also be understood as the voltage value measured when current flows through the battery. Battery SOC can be understood as the remaining charge of the battery. Batteries can be lithium iron phosphate batteries, ternary lithium batteries, etc., but the specific type of battery is not limited here.

[0041] Here, a Battery Management System (BMS) can be used to collect battery voltage and State of Charge (SOC) under different charge / discharge states. This application does not limit the battery charge / discharge strategy; for example, constant current charging, constant voltage charging, or constant current / constant voltage charging strategies can be used to control the battery SOC value during charging, or different discharge strategies can be used to control the battery SOC value during discharging. Then, a voltage sensor is used to collect the battery voltage at different SOCs. The specific data collection method can be selected according to the actual situation and is not limited here.

[0042] S202. When the battery SOC is in the plateau range, calculate the equivalent open-circuit voltage of the battery based on the battery voltage and the preset equivalent circuit model.

[0043] The battery's State of Charge (SOC) range is typically [0%, 100%]. For ease of understanding, the following will combine... Figure 3 Let's take a closer look at the division between the platform range and the non-platform range of battery SOC.

[0044] Figure 3 This is an SOC-OCV curve of a certain type of battery provided in an embodiment of this application.

[0045] like Figure 3 As shown, different battery states of charge (SOCs) correspond to different battery voltages. When the battery SOC gradually increases (or gradually decreases), the voltage will change. Figure 3The diagram only shows the state where the battery SOC gradually increases. The change in battery voltage is usually small, but sometimes large changes can occur. As an example, and not a limitation, when the battery SOC is in the range of [30%, 50%], the rate of change in battery voltage is small, essentially remaining stable; when the battery SOC is in the range of [50%, 65%], the rate of change in battery voltage is large, showing a significant jump. Therefore, the battery SOC range with a small rate of change in battery voltage (e.g., [30%, 50%]) can be called a plateau range, while the battery SOC range with a large rate of change in battery voltage (e.g., [50%, 65%]) can be called a non-plateau range. For example, in... Figure 3 In the meantime, the plateau range can also be [65%, 95%], and the non-plateau range is [95%, 100%] or [0%, 30%].

[0046] This can also be understood as follows: when the rate of change of battery voltage within a certain battery SOC range is less than a set threshold, that battery SOC range is considered a plateau range; when the rate of change of battery voltage within a certain battery SOC range is greater than a set threshold, that battery SOC range is considered a non-plateau range. Alternatively, an inflection point can be selected on the SOC-OCV curve, and the plateau and non-plateau ranges can be determined by judging whether the slope of the curves on both sides of the inflection point changes significantly. The specific plateau and non-plateau ranges of battery SOC vary depending on the battery model and battery state, and are not limited here. As mentioned above, when the battery SOC is in a plateau range, because the change in battery voltage is small, a preset equivalent circuit model is used to calculate the equivalent open-circuit voltage value.

[0047] The preset equivalent circuit model can be an n-order RC network equivalent circuit model, where n is a natural number. Examples include the Rint model (n=0), the Thevenin model, and the dual polarization (DP) model, etc. The appropriate equivalent circuit model can be selected based on the actual situation; no limitation is imposed here. The voltage value calculated using the preset equivalent circuit model can be called the equivalent open-circuit voltage value. It can also be understood as the equivalent open-circuit voltage value being close to the open-circuit voltage value. Therefore, the equivalent open-circuit voltage value can be used to replace the open-circuit voltage value when plotting the SOC-OCV curve.

[0048] When the battery's SOC is in the plateau region, the dynamic response inside the battery is in a relatively stable state, which is convenient for simulation. Using a preset equivalent circuit model to simulate the internal state of the battery and thus calculate the equivalent open circuit voltage value is simple in principle and requires little computation. At the same time, since the simulated battery state is close to the real state, the calculated equivalent open circuit voltage value is also closer to the open circuit voltage value, thus improving the accuracy of the equivalent open circuit voltage value.

[0049] S203. When the battery SOC is in the non-plateau range, the battery voltage is corrected according to the battery current to obtain the battery's equivalent open-circuit voltage value.

[0050] Combination Figure 3 It is evident that when the battery SOC is in the non-plateau region, the battery voltage changes significantly. At this time, different calculation methods can be used to calculate the battery voltage offset based on the different battery currents. Then, the actual collected battery voltage is corrected based on the battery voltage offset to obtain the battery's equivalent open-circuit voltage value.

[0051] Based on the characteristics of batteries, it is understood that the magnitude of battery current affects the magnitude of battery voltage. Therefore, calculating the battery voltage corresponding to different magnitudes of battery current can comprehensively consider the actual state of the battery, and the calculated equivalent open-circuit voltage value is more accurate and reliable.

[0052] S204. Combine the battery's SOC and equivalent open-circuit voltage values ​​to plot the battery's SOC-OCV curve.

[0053] After calculating the equivalent open-circuit voltage values ​​of the battery's SOC in the plateau range and the equivalent open-circuit voltage values ​​in the non-plateau range, the SOC-OCV curve of the battery can be plotted based on the battery's SOC and its corresponding equivalent open-circuit voltage value.

[0054] After acquiring battery voltage and SOC data, the system determines different SOC distribution ranges (plateau range or non-plateau range) and calculates them separately for each range. Specifically, in the plateau range, the equivalent open-circuit voltage value of the battery is calculated using a preset equivalent circuit model, while in the non-plateau range, the battery voltage is corrected using the battery current. This approach more comprehensively reflects the battery characteristics and the actual state of the battery, avoiding measurement errors caused by fluctuations in battery voltage. It also incorporates the actual battery conditions, resulting in a more accurate calculated equivalent open-circuit voltage value. Consequently, the obtained SOC-OCV curve is closer to the true SOC-OCV curve, improving the accuracy of the battery SOC-OCV curve.

[0055] To more intuitively demonstrate the effect of the improved SOC-OCV curve, the following section combines... Figure 4 Let me explain in detail.

[0056] Figure 4 This is an SOC-OCV curve of a certain type of battery obtained by using the SOC-OCV curve generation method of the present application in one embodiment of the present application.

[0057] like Figure 4 As shown, Figure 4The curve formed by connecting the black data points represents the standard SOC-OCV curve of the battery, while the curve formed by connecting the white (hollow) data points represents the improved SOC-OCV curve obtained by the battery using steps S201 to S204 above. Figure 1 Compared to the SOC-OCV curve plotted directly without modification, Figure 4 The improved SOC-OCV curve is significantly closer to the standard SOC-OCV curve, better reflecting the actual state of the battery. It can more accurately display the actual relationship between battery voltage and battery SOC, which is conducive to more accurate estimation of battery SOC during battery use. In turn, it can show users a more realistic remaining battery capacity, making it more convenient for users and meeting their expectations.

[0058] Understandably, this is for ease of distinction. Figure 4 The image only shows a portion of the white data points on the fitted SOC-OCV curve. In practical applications, the more actual battery SOC and equivalent open-circuit voltage values ​​are determined, the more white data points there will be, and the curve will converge to the standard SOC-OCV curve.

[0059] The following example will further illustrate how to calculate the equivalent open-circuit voltage of a battery when its state of charge (SOC) is in the non-plateau range.

[0060] In one implementation, when the battery SOC is in the non-plateau range, the battery voltage is corrected based on the battery current to obtain the battery's equivalent open-circuit voltage value. This includes: when the battery SOC is in the non-plateau range and the battery's operating parameters meet preset conditions, calculating the battery's voltage offset based on the battery current. The operating parameters include at least one of the following: battery temperature and battery current; and correcting the battery voltage based on the battery's voltage offset to obtain the battery's equivalent open-circuit voltage value.

[0061] By detecting whether the battery's operating parameters meet preset conditions, that is, by detecting the actual situation of the battery temperature and battery current, it can be determined whether the battery itself is in a relatively stable charging and discharging state.

[0062] It's understandable that during charging or discharging, chemical reactions and current flow occur within a battery, causing changes in the distribution of charge and energy inside the battery. At the start of charging or discharging, the internal chemical reactions and current flow may be unstable, leading to fluctuations in voltage and current. Over time, the internal chemical reactions gradually stabilize, and the charge and energy distribution gradually reach equilibrium, eventually achieving a stable state. If battery voltage is corrected while the battery is in an unstable state, it may be affected by various factors such as current and temperature. Fluctuations in these factors can lead to instability in the obtained battery voltage value, thus affecting the accuracy of the calculated voltage offset.

[0063] After confirming that the battery is in a stable state, the voltage offset can be calculated based on the battery current. The voltage offset can be understood as the difference between the measured battery voltage and the actual battery voltage. By calculating the voltage offset, we can know whether the measured battery voltage is too high or too low relative to the actual battery voltage. The battery voltage corrected based on the voltage offset can be regarded as the battery's equivalent open-circuit voltage value.

[0064] By determining whether the battery's operating parameters meet the preset conditions, the battery voltage can be corrected under stable conditions. This makes the entire correction process closer to the battery's actual performance and state, thus better ensuring the accuracy and reliability of the correction process and improving the accuracy of the calculated equivalent open-circuit voltage value of the battery.

[0065] The following examples illustrate the selection range of preset conditions.

[0066] In one implementation, the preset conditions include: the battery temperature is greater than a first preset temperature, and the battery current is a charging current and the time during which the battery current is less than a first preset current value is greater than a first preset duration; or, the battery temperature is greater than a first preset temperature, and the battery current is a discharging current and the time during which the battery current is less than a first preset current value is greater than a first preset duration.

[0067] Taking lithium iron phosphate batteries as an example, the first preset temperature can be 10℃, the first preset current value can be 0.2C (C is the battery charge / discharge capacity ratio), and the first preset duration can be 2 hours. In other words, if the battery's operating parameters meet the following conditions: the battery temperature is greater than 10℃ and the battery current during charging is less than 0.2C for more than 2 hours; or, the battery temperature is greater than 10℃ and the battery current during discharging is less than 0.2C for more than 2 hours, then the battery can be considered to meet the preset conditions, meaning it is considered to be in a stable state and can undergo battery voltage correction processing.

[0068] The specific preset values ​​vary depending on the battery model and condition; this is just an example and not a limitation.

[0069] By strictly controlling the battery temperature, the magnitude of the battery current, and the duration of the battery current, the stability of the measured battery voltage can be ensured, thereby improving the accuracy of the battery voltage correction process.

[0070] The following example illustrates how to calculate the battery voltage offset based on the battery current.

[0071] In one implementation, when the battery is in a charging state, the battery voltage offset is calculated based on the battery current, including:

[0072] When the battery current is greater than the second preset current value and the minimum single cell voltage of the battery is less than the preset voltage value, the first charging voltage offset of the battery is calculated based on the battery current, the full charge capacity of the battery and the first bias.

[0073] When the battery current is greater than the second preset current and the minimum single cell voltage is greater than or equal to the preset voltage, the second charging voltage offset of the battery is calculated based on the battery current, the battery's full charge capacity, and the second bias; wherein the value of the second charging voltage offset is greater than the value of the first charging voltage offset.

[0074] When the battery current is less than or equal to the second preset current, the third charging voltage offset of the battery is calculated based on the battery current and the battery's full charge capacity.

[0075] Taking lithium iron phosphate batteries as an example, the second preset current value can be 0.05C, the preset voltage value can be 3250mV, and the first and second bias values ​​are constants that can be set according to the battery characteristics and actual data.

[0076] For example, when the battery current is greater than 0.05C and the minimum single-cell voltage of the battery is less than 3250mV, the first charging voltage offset of the battery, calculated based on the battery current, the full charge capacity of the battery, and the first bias, can be expressed as the following formula (1):

[0077] V offset1 =100*I / C full +20, (1)

[0078] Among them, V offset Indicates the first charging voltage offset, I represents the battery current, and C represents the battery current. full This indicates the battery's full charge capacity, with the first bias being a constant of 20.

[0079] For example, when the battery current is greater than 0.05C and the minimum single cell voltage of the battery is greater than or equal to 3250mV, the second charging voltage offset of the battery, calculated based on the battery current, the full charge capacity of the battery, and the second bias, can be expressed as the following formula (2):

[0080] V offset =107 * I / C full +39, (2)

[0081] Among them, V offset Indicates the second charging voltage offset, I represents the battery current, and C represents the battery current. full This indicates the battery's full charge capacity, and the second bias is a constant of 39.

[0082] For example, when the battery current is less than or equal to 0.05C, the third charging voltage offset of the battery, calculated based on the battery current and the battery's full charge capacity, can be expressed as the following formula (3):

[0083] V offset =800*I / C full (3)

[0084] Among them, V offset Indicates the offset of the third charging voltage, I represents the battery current, and C represents the third charging voltage offset. full This indicates the battery's full charge capacity.

[0085] The specific numerical settings vary depending on the battery model and battery status; this is just an example and not a limitation.

[0086] In one implementation, when the battery is in a discharging state, the battery voltage offset is calculated based on the battery current, including:

[0087] When the battery current is less than or equal to the second preset current value, the first discharge voltage offset of the battery is calculated based on the battery current and the full charge capacity of the battery, wherein the first discharge voltage offset is a positive integer multiple of the ratio of the battery current to the full charge capacity of the battery.

[0088] When the battery current value is greater than the second preset current value, the second discharge voltage offset of the battery is calculated based on the battery current, the battery's full charge capacity, and the third bias.

[0089] Based on the above, taking lithium iron phosphate batteries as an example, the second preset current value can be 0.05C, and the third bias is a constant, which can be set according to the battery characteristics and actual data.

[0090] For example, when the battery current is less than or equal to 0.05C, the first discharge voltage offset of the battery, calculated based on the battery current and the battery's full charge capacity, can be expressed as the following formula (4):

[0091] V offset =300*I / C full (4)

[0092] Among them, V offset Indicates the first discharge voltage offset, I represents the battery current, and C represents the current. full This indicates the battery's full charge capacity.

[0093] For example, when the battery current is greater than 0.05C, the second discharge voltage offset of the battery, calculated based on the battery current, the battery's full charge capacity, and the third bias, can be expressed as the following formula (5):

[0094] V offset =110*I / C full –15, (5)

[0095] Among them, V offset Indicates the second discharge voltage offset, I represents the battery current, and C represents the battery current. full This indicates the battery's full charge capacity, and the third bias is a constant -15.

[0096] Combining the above formulas (1) to (5), after calculating the voltage offset under different charging and discharging conditions, the minimum single-cell voltage correction can be calculated by combining the measured minimum single-cell voltage, as shown in the following formula (6):

[0097] V MinCelloffset =V mincell -V offset (6)

[0098] Among them, V MinCelloffset Indicates the minimum unit voltage correction, V mincell This indicates the minimum voltage of a single unit.

[0099] Furthermore, the maximum single-cell voltage correction can be calculated by combining the measured maximum single-cell voltage, as shown in equation (7):

[0100] V MaxCelloffset =V maxcell –V offset (7)

[0101] Among them, V MaxCelloffset Indicates the highest single-unit voltage correction, V maxcell This indicates the maximum voltage of a single unit.

[0102] Finally, the equivalent open-circuit voltage V of the battery in the non-plateau region is calculated using the following equation (8). EcloudSoc .

[0103] V EcloudSoc =V MinCellOffset*(100–SOC)+V MaxCellOffset *SOC, (8)

[0104] By using the above calculation method and combining the battery current under different conditions to calculate the voltage offset under different conditions, the different battery states can be fully reflected, making the final calculated equivalent open-circuit voltage value more accurate.

[0105] The following is combined with Figure 5 This section provides a general overview of the process for calculating the equivalent open-circuit voltage when the battery's state of charge (SOC) is in the non-plateau range.

[0106] Figure 5 This is a schematic flowchart illustrating a process for calculating the equivalent open-circuit voltage when the battery's state of charge (SOC) is in the non-plateau range, as provided in an embodiment of this application.

[0107] like Figure 5 As shown, Figure 5 The process includes the following steps S501 to S5015.

[0108] S501, measures battery current and battery temperature.

[0109] S502. Determine whether the current direction remains unchanged and the current temperature is greater than 10℃.

[0110] S503, obtain the invalid value of the equivalent open-circuit voltage.

[0111] If the current direction does not remain unchanged and the current temperature is greater than 10℃, it indicates that the battery is not in a stable state, and an invalid value of the equivalent open circuit voltage is obtained. In this case, the cloud platform will not update the data.

[0112] S504, The cloud platform does not update invalid values.

[0113] S505, Measure the duration of current.

[0114] S506. Determine whether the current duration is greater than 2 hours.

[0115] S507, obtain the invalid value of the equivalent open-circuit voltage.

[0116] If the current duration does not meet the requirement of being greater than 2 hours, an invalid value of the equivalent open-circuit voltage will be obtained, and the cloud platform will not perform any update processing in this case.

[0117] S508, Calculate voltage offset.

[0118] S509. Determine if the battery is in a discharged state.

[0119] S5010, Calculate the first discharge voltage offset and the second discharge voltage offset.

[0120] S5011. Determine if the battery is charging.

[0121] S5012. Calculate the first charging voltage offset, the second charging voltage offset, and the third charging voltage offset.

[0122] S5013. Calculate the equivalent open-circuit voltage value based on the voltage offset.

[0123] S5014, obtain the effective value of the equivalent open-circuit voltage.

[0124] S5015, Cloud Platform Update Valid Values.

[0125] Understandably, after the data is transmitted to the cloud platform, users can access this data anytime, anywhere via the Internet for real-time monitoring, analysis, and management. In other words, by transmitting the battery voltage and battery SOC data to the cloud platform, users can remotely monitor and manage the battery status.

[0126] In one implementation, the equivalent open-circuit voltage of the battery is calculated based on the battery voltage and a preset equivalent circuit model, including:

[0127] The equivalent open-circuit voltage of the battery is calculated based on the battery voltage and the second-order equivalent circuit model.

[0128] To facilitate understanding, the following will be combined with... Figure 6 This application provides a detailed description of a second-order equivalent circuit model.

[0129] Figure 6 This is a circuit diagram of a second-order equivalent circuit model provided in an embodiment of this application.

[0130] like Figure 6 As shown, OCV is a voltage source, representing the open-circuit voltage when the battery is in a fully balanced state; R0 is the internal resistance in ohms; R pi and C pi These are the polarization resistor and polarization capacitor, respectively; U pi I is the polarization voltage; I is the terminal current, which is positive during battery charging and negative during battery discharging; U is the terminal voltage.

[0131] By combining the battery voltage and identifying the parameters of the established second-order equivalent circuit model, the equivalent open-circuit voltage value can be calculated. The specific calculation principle and process are introduced below.

[0132] Based on Kirchhoff's laws, the equation of the nth-order RC equivalent circuit model in the continuous domain can be expressed as the following equation (9):

[0133]

[0134] Where t is the time variable and i is a natural number determined by the order n. The more RC networks composed of polarization resistors and polarization capacitors connected in parallel, the more accurate the description of the battery polarization voltage, but the heavier the computational burden. Under zero initial conditions, the Laplace transform of the above equation (9) yields the transfer function of the nth-order RC equivalent circuit model. The s of the transfer function is a complex variable representing the system response frequency, as shown in the following equation (10):

[0135] Equation (10) is discretized using Equation (11) to obtain Equation (12), where Equation (11) is an expression for a zero-order hold, and z in Equation (12) is a variable that is discretized.

[0136]

[0137]

[0138] Among them, T s The system sampling period is T, which is taken in this paper. s =1s. Then the discrete-time model of the nth-order RC equivalent circuit model can be obtained as shown in equation (13).

[0139]

[0140] Where a i and b j The values ​​are calculated from the battery parameter model; k represents the current cycle, and (ki) represents the (ki)th cycle.

[0141] After establishing the battery model, the battery model parameters are still unknown. It is necessary to identify the established battery model parameters. The parameters to be identified are open circuit voltage OCV, ohmic internal resistance R0, polarization internal resistance R1 and R2, and polarization capacitance C1 and C2.

[0142] The following diagram will illustrate how to identify the parameters to be identified.

[0143] Figure 7 This is a schematic diagram of an HPPC (Hybrid Pulse Power Characterization) voltage response curve provided in an embodiment of this application.

[0144] like Figure 7 As shown, Figure 7The data includes five voltage sampling points, U1 to U5. It can be clearly seen that the voltage drops instantaneously from U1 to U2, then slowly drops to U3, then rises to U4, and finally slowly rises to U5. In other words, due to the presence of ohmic internal resistance, the voltage changes abruptly from U1 to U2 at the instant the current starts, and changes abruptly from U3 to U4 at the instant the current is removed.

[0145] The ohmic internal resistance can be calculated by taking the average of the two voltages, as shown in equation (14):

[0146]

[0147] U4→U5 can be considered as a zero-input response, and the voltage expression is shown in equation (15):

[0148]

[0149] The curve (U4→U5) can be obtained by curve fitting using the parameters of the second-order RC equivalent circuit model, and the fitting expression is as follows (16):

[0150]

[0151] Where A1 and A2 are constant values ​​obtained from the fitting.

[0152] By comparing equations (15) and (16), we can obtain equation (17):

[0153]

[0154] Now that the parameters R0, R1, R2, C1, and C2 are obtained, Uocv can be obtained according to formula (9), which is the equivalent open-circuit voltage value of the battery in the plateau range.

[0155] Using a second-order equivalent circuit model to calculate the equivalent open-circuit voltage can ensure the accuracy of the calculation results, control the complexity of the calculation process, and guarantee calculation efficiency.

[0156] In one implementation, when the battery SOC is in a non-plateau range and the battery's operating parameters do not meet preset conditions, the battery voltage is screened and confirmed as an invalid value, and the equivalent open-circuit voltage corresponding to the battery voltage is not calculated.

[0157] In other words, if the battery's operating parameters do not meet the preset conditions, the measured battery voltage is considered invalid, and the equivalent open-circuit voltage corresponding to the invalid battery voltage is not calculated.

[0158] By filtering out invalid battery voltage values, unnecessary calculations can be avoided for batteries in unstable states, improving the efficiency of the battery voltage correction process. It can also prevent invalid values ​​from interfering with the calculation of battery voltage offset in stable states, thus improving the accuracy of battery voltage correction.

[0159] In one implementation, the SOC-OCV curve is sent to the energy storage device corresponding to the battery.

[0160] It's understandable that in a battery management system (BMS), the battery's State of Charge (SOC) can be estimated by measuring its open-circuit voltage, thus enabling monitoring and control of the battery's state. The higher the accuracy of the SOC-OCV curve, the smaller the error between the estimated SOC value and the actual battery capacity. If the accuracy of the SOC-OCV curve is low, the estimated SOC value may differ significantly from the actual battery capacity, leading to misjudgments and malfunctions in the BMS.

[0161] After generating the improved SOC-OCV curve using the above steps, the improved SOC-OCV can be sent to the corresponding energy storage device. After receiving the SOC-OCV curve, the energy storage device can re-estimate the battery SOC using the more accurate and precise SOC-OCV curve, thereby improving the accuracy of battery SOC estimation and making it easier to present the most realistic remaining battery capacity to the user.

[0162] The methods of the embodiments of this application have been described above with reference to the accompanying drawings. It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially, these steps are not necessarily executed in the order shown in the figures. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the steps or stages of other steps. The apparatus of one embodiment of this application will now be described with reference to the accompanying drawings. For brevity, appropriate omissions will be made in the following description of the apparatus; relevant content can be referred to in the relevant descriptions of the methods above, and will not be repeated.

[0163] Figure 8 A schematic diagram of the structure of a device provided in the application embodiment.

[0164] like Figure 8 As shown, the device 1000 includes the following units.

[0165] The acquisition unit 1001 is used to acquire the battery voltage and battery SOC.

[0166] The processing unit 1002 is used to calculate the equivalent open-circuit voltage of the battery based on the battery voltage and a preset equivalent circuit model when the battery SOC is in the plateau range.

[0167] The processing unit 1002 is also used to correct the battery voltage based on the battery current when the battery SOC is in the non-plateau range, so as to obtain the equivalent open circuit voltage value of the battery.

[0168] The processing unit 1002 is also used to plot the SOC-OCV curve of the battery by combining the battery SOC and the equivalent open-circuit voltage value.

[0169] The processing unit 1002 described above can also be used to execute the methods in steps S501 to S5015 described above.

[0170] In one implementation, the device 1000 further includes a storage unit 1003, which can be used to store instructions and / or data, thereby implementing the method in the above embodiments.

[0171] It should be noted that the information interaction and execution process between the above-mentioned units are based on the same concept as the method embodiments of this application. For details on their specific functions and technical effects, please refer to the method embodiments section, which will not be repeated here.

[0172] Figure 9 This is a schematic diagram of the structure of the computer device provided in an embodiment of this application. Figure 9 As shown, the computer device 3000 of this embodiment includes: at least one processor 3100 ( Figure 9 (Only one is shown) a processor, a memory 3200, and a computer program 3210 stored in the memory 3200 and executable on at least one processor 3100, wherein when the processor 3100 executes the computer program 3210, the computer device performs the steps described in the above embodiments.

[0173] The processor 3100 can be a Central Processing Unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0174] In some embodiments, memory 3200 may be an internal storage unit of computer device 3000, such as a hard disk or RAM of computer device 3000. In other embodiments, memory 3200 may be an external storage device of computer device 3000, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., provided on computer device 3000. Furthermore, memory 3200 may include both internal and external storage units of computer device 3000. Memory 3200 is used to store operating system, application programs, boot loader data, and other programs, such as program code for computer programs. Memory 3200 may also be used to temporarily store data that has been output or will be output.

[0175] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units is merely an example. In practical applications, the above functions can be assigned to different functional units or modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0176] This application also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a computer device, it enables the computer device to perform the steps described in the above-described method embodiments.

[0177] This application provides a computer program product that, when run on a computer device, enables the computer device to implement the methods described above.

[0178] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of this application can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it enables a computer device to implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a photographing device / terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electrical carrier signals or telecommunication signals.

[0179] It should be understood that the sequence numbers of the steps in the above embodiments do not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application. In the description, specific details such as particular system structures and technologies are set forth for illustrative purposes rather than for limiting purposes, so as to provide a thorough understanding of the embodiments of this application. However, those skilled in the art should understand that this application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary details.

[0180] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0181] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0182] Furthermore, in the description of this application and the appended claims, the terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0183] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0184] 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.

[0185] In the embodiments provided in this application, it should be understood that the disclosed apparatus, computer equipment, and methods can be implemented in other ways. For example, the apparatus and computer equipment 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. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0186] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for generating the SOC-OCV curve of a battery, characterized in that, include: Obtain the battery voltage and battery SOC; When the battery's SOC is in the plateau range, the equivalent open-circuit voltage of the battery is calculated based on the battery voltage and a preset equivalent circuit model. When the battery SOC is in the non-plateau range, the battery voltage is corrected according to the battery current to obtain the equivalent open-circuit voltage value of the battery. Plot the SOC-OCV curve of the battery by combining the battery's SOC and the equivalent open-circuit voltage value; When the battery's SOC is in a non-plateau range, the battery voltage is corrected based on the battery current to obtain the battery's equivalent open-circuit voltage value, including: When the battery SOC is in the non-plateau range and the battery operating parameters meet preset conditions, the voltage offset of the battery is calculated based on the battery current. The operating parameters include at least one of the following: battery temperature and battery current. The battery voltage is corrected based on the battery voltage offset to obtain the battery's equivalent open-circuit voltage value.

2. The method according to claim 1, characterized in that, The preset conditions include: The battery temperature is greater than a first preset temperature, the battery current is the charging current, and the time during which the battery current is less than a first preset current value is greater than a first preset duration; or... The battery temperature is greater than a first preset temperature, the battery current is a discharge current, and the time during which the battery current is less than a first preset current value is greater than a first preset duration.

3. The method according to claim 1, characterized in that, When the battery is in a charging state, the calculation of the battery voltage offset based on the battery current includes: When the battery current is greater than the second preset current value and the minimum single cell voltage value of the battery is less than the preset voltage value, the first charging voltage offset of the battery is calculated based on the battery current, the full charge capacity of the battery and the first bias. When the current value of the battery is greater than the second preset current value and the minimum single-cell voltage value of the battery is greater than or equal to the preset voltage value, the second charging voltage offset of the battery is calculated based on the battery current, the full charge capacity of the battery and the second bias; wherein, the value of the second charging voltage offset is greater than the value of the first charging voltage offset. When the current value of the battery is less than or equal to the second preset current value, the third charging voltage offset of the battery is calculated based on the battery current and the full charge capacity of the battery.

4. The method according to claim 1, characterized in that, When the battery is in a discharging state, the calculation of the battery voltage offset based on the battery current includes: When the battery current is less than or equal to the second preset current value, the first discharge voltage offset of the battery is calculated based on the battery current and the full charge capacity of the battery, wherein the first discharge voltage offset is a positive integer multiple of the ratio of the battery current to the full charge capacity of the battery. When the current value of the battery is greater than the second preset current value, the second discharge voltage offset of the battery is calculated based on the battery current, the full charge capacity of the battery, and the third bias.

5. The method according to claim 1, characterized in that, The step of calculating the equivalent open-circuit voltage of the battery based on the battery voltage and a preset equivalent circuit model includes: The equivalent open-circuit voltage of the battery is calculated based on the battery voltage and the second-order equivalent circuit model.

6. The method according to claim 1, characterized in that, The method further includes: When the battery SOC is in a non-platform range and the battery's operating parameters do not meet preset conditions, the battery voltage is screened and confirmed as an invalid value, and the equivalent open-circuit voltage corresponding to the battery voltage is not calculated.

7. The method according to claim 1, characterized in that, The method further includes: The SOC-OCV curve is sent to the energy storage device corresponding to the battery.

8. A computer device, characterized in that, The device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it causes the computer device to implement the method for generating the SOC-OCV curve of a battery as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a computer device, implements the method for generating the SOC-OCV curve of a battery as described in any one of claims 1 to 7.

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