Method and device for measuring and calculating state of charge of sodium ion battery

Abstract

The present application discloses a method and device for measuring and calculating the state of charge (SOC) of a sodium ion battery. The method comprises: firstly, on the basis of a current integration method, outputting a real-time SOC to be calibrated; when a real-time current lasts for a preset duration of zero, starting to calibrate said SOC; by considering the effect of a battery temperature on said SOC, obtaining a plurality of curves in advance by testing in different temperatures of a sodium ion battery; during calibration, using a current real-time voltage, a current real-time temperature, a first curve, and a second curve to perform linear difference calculation of said SOC for multiple times to obtain the SOC corresponding to the current real-time temperature; and using the SOC corresponding to the current real-time temperature to calibrate said real-time SOC.

Description

Method and apparatus for calculating the state of charge of sodium-ion batteries

[0001] Related applications

[0002] This application claims priority to Chinese Patent Application No. 202411641681.X, filed on November 15, 2024, and incorporates the disclosure of the aforementioned patent application as part of this application. Technical Field

[0003] This application relates to the field of battery management technology, and in particular to a method and apparatus for calculating the state of charge of a sodium-ion battery. Background Technology

[0004] This section is intended to provide background or context for the embodiments of this application set forth in the claims. The description herein is not an admission that it is prior art simply because it is included in this section.

[0005] Currently, the new energy industry is booming, with huge demands for batteries from sectors such as power, energy storage, vehicles, ships, and aviation. The mainstream battery technology is lithium-ion batteries, primarily including lithium iron phosphate batteries and ternary lithium batteries. However, lithium mines are unevenly distributed globally, and supply stability is difficult to guarantee due to various factors. Sodium-ion batteries offer a solution with lower material costs, higher safety, and a more stable supply compared to lithium-ion batteries. When the supply of lithium-ion battery materials is limited, sodium-ion batteries are an effective alternative. However, current sodium-ion battery supporting technologies are still immature, and supporting equipment suffers from performance limitations, high costs, and unstable solutions, requiring collaborative improvement from all sectors of society.

[0006] Sodium-ion battery management systems (SMS) are the main devices used for monitoring, measuring, and protecting sodium-ion batteries. One of their core functions is the calculation of the battery's SOC (State of Charge, which represents the ratio of the battery's current remaining capacity to its total capacity, usually expressed as a percentage). Current sodium-ion battery SOC calculations primarily rely on direct and brute-force methods such as current integration or Kalman filtering. However, directly applying these methods to sodium-ion battery SOC calculations results in inaccuracies in the measured SOC values. Summary of the Invention

[0007] This application provides a method for calculating the state of charge (SOC) of a sodium-ion battery to improve the accuracy of SOC calculation. The method includes:

[0008] Based on the current integration method, the real-time state of charge (SOC) of sodium-ion batteries is output using the real-time current and time information.

[0009] Monitor the real-time current, real-time temperature, and real-time voltage of sodium-ion batteries;

[0010] When the real-time current remains at zero for a preset duration, the first curve and the second curve with the smallest difference in test temperature are selected from the preset curve library based on the current real-time temperature. The preset curve library stores multiple curves that reflect the mapping relationship between open-circuit voltage and SOC. Any two curves are obtained by testing at different test temperatures, where the test temperature is the temperature of the sodium-ion battery. The current real-time temperature is between the test temperatures of the first curve and the second curve.

[0011] By using the current real-time voltage, current real-time temperature, first curve and second curve to perform linear difference calculation of SOC multiple times, the SOC corresponding to the current real-time temperature is obtained;

[0012] The real-time SOC is corrected using the SOC corresponding to the current real-time temperature.

[0013] In one embodiment, based on the current integration method, the real-time SOC is output using the real-time current and time information of the sodium-ion battery, including: acquiring the initial charge; performing current integration using the real-time current and time interval to obtain the charge; determining the charge change value based on the current charging / discharging direction and the charge; the current charging / discharging direction includes the charging direction and the discharging direction, where the charge is positive during the charging direction and negative during the discharging direction; and determining the real-time SOC based on the initial charge, the charge change value, and the battery's actual maximum capacity.

[0014] In one embodiment, determining the real-time SOC based on the initial SOC, the change in charge value, and the actual maximum capacity of the battery includes:

[0015] The real-time SOC is determined using the following formula, based on the initial SOC, the change in charge, and the battery's actual maximum capacity:

[0016] SOC real-time = (Qt0 + △Qchg + △Qdsg) / Qmax;

[0017] In the formula, SOC real-time is the real-time SOC, Qt0 is the initial charge, △Qchg is the change in charge during the statistical time interval, △Qdsg is the change in charge during the statistical time interval, and Qmax is the current actual maximum capacity of the battery.

[0018] In one embodiment, the SOC corresponding to the current real-time temperature is obtained by performing linear difference calculations multiple times using the current real-time voltage, the current real-time temperature, the first curve, and the second curve. This includes: performing linear difference calculations using the current real-time voltage, the first curve, and the second curve to obtain the first SOC and the second SOC corresponding to the current real-time voltage on the first curve and the second curve, respectively; and performing linear difference calculations using the current real-time temperature, the test temperature of the first curve, the first SOC, and the test temperature of the second curve, and the second SOC to obtain the SOC corresponding to the current real-time temperature.

[0019] In one embodiment, a linear difference calculation is performed using the current real-time voltage, a first curve, and a second curve to obtain the first SOC and second SOC corresponding to the current real-time voltage on the first and second curves, respectively. This includes: using the current real-time voltage, determining two points on the first and second curves where the difference in open-circuit voltage is the smallest; the current real-time voltage is between the open-circuit voltages of the two points; performing a linear difference calculation using the open-circuit voltage and SOC of the two points on the first curve to obtain the first SOC corresponding to the current real-time voltage on the first curve; and performing a linear difference calculation using the open-circuit voltage and SOC of the two points on the second curve to obtain the second SOC corresponding to the current real-time voltage on the second curve.

[0020] In one embodiment, after monitoring the real-time current, real-time temperature, and real-time voltage of the sodium-ion battery, the method further includes:

[0021] When the sodium-ion battery is in charging mode, when a charging cut-off event is triggered, the real-time SOC is corrected to 100%; the charging cut-off event includes a real-time current of zero.

[0022] When the sodium-ion battery is in discharge mode, when a discharge cutoff event is triggered, the real-time SOC is corrected to 0%; the discharge cutoff event includes a real-time current of zero.

[0023] In one embodiment, after monitoring the real-time current, real-time temperature, and real-time voltage of the sodium-ion battery, the method further includes:

[0024] Record the state of charge (SOCt1) and charge (Qt1) at the first time point t1;

[0025] When the sodium-ion battery is operating normally at the second time point t2, the state of charge SOCt2 and the charge Qt2 are recorded; where the difference between SOCt2 and SOCt1 reaches the set threshold.

[0026] When t1 to t2 is the discharge process, the latest maximum capacitance is determined by the following formula: Q'max=(Qt2-Qt1) / (SOCt1-SOCt2);

[0027] When t1 to t2 is the charging process, the latest maximum capacity is determined by the following formula: Q'max=(Qt2-Qt1) / (SOCt2-SOCt1);

[0028] In the formula, Q'max is the latest maximum capacitance.

[0029] In one embodiment, after determining the latest maximum capacity, the method further includes: calibrating the real-time SOC using the latest maximum capacity.

[0030] This application also provides a sodium-ion battery state-of-charge (SOC) measurement device to improve the accuracy of SOC measurement for sodium-ion batteries. The device includes:

[0031] The power statistics module is used to output the real-time state of charge (SOC) based on the real-time current and time information of the sodium-ion battery using the current integration method.

[0032] The data acquisition module is used to monitor the real-time current, real-time temperature, and real-time voltage of the sodium-ion battery.

[0033] The OCV calibration module is used to select the first and second curves with the smallest difference in test temperatures from a preset curve library when the real-time current remains zero for a preset duration, based on the current real-time temperature. The preset curve library stores multiple curves reflecting the mapping relationship between open-circuit voltage and state of charge (SOC). Any two curves are obtained by testing at different test temperatures, where the test temperature is the temperature of the sodium-ion battery. The current real-time temperature is between the test temperatures of the first and second curves. The module calculates the linear difference in SOC multiple times using the current real-time voltage, current real-time temperature, and the first and second curves to obtain the SOC corresponding to the current real-time temperature. The real-time SOC is then corrected using the SOC corresponding to the current real-time temperature.

[0034] This application also provides 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 implements the above-described method for calculating the state of charge of a sodium-ion battery.

[0035] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for calculating the state of charge of a sodium-ion battery.

[0036] This application also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described method for calculating the state of charge of a sodium-ion battery.

[0037] In this embodiment, the real-time SOC to be calibrated is first output based on the current integration method. SOC calibration is initiated when the real-time current remains at zero for a preset duration. Considering the influence of battery temperature on SOC, multiple curves are obtained beforehand at different sodium-ion battery temperatures. During calibration, the linear difference of SOC is calculated multiple times using the current real-time voltage, current real-time temperature, the first curve, and the second curve to obtain the SOC corresponding to the current real-time temperature, thus obtaining a more accurate SOC. This more accurate SOC is then used to calibrate the aforementioned real-time SOC. Compared with existing technical solutions, this embodiment can significantly improve the accuracy of sodium-ion battery SOC measurement. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0039] Figure 1 is a flowchart illustrating the method for calculating the state of charge of a sodium-ion battery in an embodiment of this application.

[0040] Figure 2 is a specific example of the sodium-ion battery state-of-charge calculation method in this application.

[0041] Figure 3 is a schematic diagram of the OCV-SOC curve of the sodium-ion battery in the embodiment of this application;

[0042] Figure 4 is a schematic diagram of the current reduction process of the sodium-ion battery system in an embodiment of this application;

[0043] Figure 5 is another specific example of the sodium-ion battery state-of-charge calculation method in the embodiments of this application;

[0044] Figure 6 is a schematic diagram of the sodium-ion battery state-of-charge measurement device in an embodiment of this application. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the embodiments of this application will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments and their descriptions are used to explain this application, but are not intended to limit this application.

[0046] A sodium-ion battery management system (BMS) is a key device for monitoring, calculating, and protecting sodium-ion batteries. One of its core functions is calculating the state of charge (SOC) of the battery. Because different types of batteries have significantly different characteristics, different battery management systems need algorithms adapted to these battery characteristics to accurately estimate the charge level of sodium-ion batteries during use.

[0047] Figure 1 is a flowchart illustrating the method for calculating the state of charge of a sodium-ion battery in an embodiment of this application. As shown in Figure 1, the method includes:

[0048] Step 101: Based on the current integration method, output the real-time SOC using the real-time current and time information of the sodium-ion battery;

[0049] Step 102: Monitor the real-time current, real-time temperature, and real-time voltage of the sodium-ion battery;

[0050] Step 103: When the real-time current is continuously zero for a preset duration, based on the current real-time temperature, select the first curve and the second curve with the smallest difference in test temperature from the preset curve library; The preset curve library stores multiple curves reflecting the mapping relationship between open-circuit voltage and SOC. Any two curves are obtained by testing at different test temperatures, and the test temperature is the temperature of the sodium-ion battery; The current real-time temperature is between the test temperatures of the first curve and the second curve.

[0051] Step 104: Calculate the linear difference of SOC multiple times using the current real-time voltage, current real-time temperature, first curve, and second curve to obtain the SOC corresponding to the current real-time temperature;

[0052] Step 105: Correct the real-time SOC using the SOC corresponding to the current real-time temperature.

[0053] As shown in Figure 1, in this embodiment, the real-time SOC to be calibrated is first output based on the current integration method. SOC calibration is initiated when the real-time current remains at zero for a preset duration. Considering the influence of battery temperature on SOC, this embodiment obtains multiple curves beforehand at different sodium-ion battery temperatures. During calibration, the linear difference of SOC is calculated multiple times using the current real-time voltage, current real-time temperature, the first curve, and the second curve to obtain the SOC corresponding to the current real-time temperature, thus obtaining a more accurate SOC. This more accurate SOC is then used to calibrate the aforementioned real-time SOC. Compared with existing technologies, this embodiment significantly improves the accuracy of sodium-ion battery SOC measurement.

[0054] Furthermore, after obtaining the corrected real-time SOC, the remaining driving range can be dynamically calculated based on the current energy consumption and the corrected real-time SOC; and / or the energy storage system can calculate the sustainable power supply time based on the load power and the corrected real-time SOC. If the sustainable power supply time is less than or equal to a preset time, a low battery warning will be sent to the user. For example, after obtaining the corrected real-time SOC, when the corrected real-time SOC shows that the battery is fully charged (e.g., SOC = 100%), a command can be issued to terminate charging to prevent overcharging.

[0055] During implementation, the sodium-ion battery management system has a built-in battery model, and the real-time acquired data includes voltage V, temperature T, current I, maximum capacity Qmax, charge Q, and state of charge (SOC). Specifically, this data can be measured using corresponding sensors or converters; that is, the voltage V is measured by a voltage sensor (or analog-to-digital converter) and sent to the server, the temperature T is measured by a temperature sensor and sent to the server, and the current I is measured by a current sensor and sent to the server. Upon receiving the voltage V, temperature T, and current I data, and calculating the maximum capacity Qmax, charge Q, and SOC data, the server executes steps 101-105 above. Furthermore, it should be noted that the method for calculating the maximum capacity Qmax, charge Q, and SOC data can be consistent with any method for determining these data, and this application will not elaborate on this aspect.

[0056] Generally, the real-time state of charge (SOC) is first output based on the current integration method using the real-time current and time information of the sodium-ion battery; then, SOC calibration is performed when the calibration conditions are met.

[0057] When calibration conditions are not met, the SOC is calculated based on changes in charge, and the charge is accumulated based on the current.

[0058] Figure 2 is a specific example of the sodium-ion battery state-of-charge (SOC) calculation method in this application. As shown in Figure 2, based on the current integration method, the real-time SOC is output using the real-time current and time information of the sodium-ion battery, which may include:

[0059] Step 201: Obtain the initial battery level;

[0060] Step 202: Integrate the current using the real-time current and the time interval to obtain the charge.

[0061] Step 203: Determine the change in charge based on the current charging / discharging direction and charge amount; the current charging / discharging direction includes the charging direction and the discharging direction. In the charging direction, the charge amount is positive, and in the discharging direction, the charge amount is negative.

[0062] Step 204: Determine the real-time SOC based on the initial charge, the change in charge, and the battery's actual maximum capacity.

[0063] Furthermore, determining the real-time SOC based on the initial SOC, the change in charge, and the battery's actual maximum capacity can include:

[0064] The real-time SOC is determined using the following formula, based on the initial SOC, the change in charge, and the battery's actual maximum capacity: SOC 实时 =(Q t0 +△Q chg +△Q dsg ) / Q max ;

[0065] In the formula, SOC 实时 For real-time SOC, Q t0 For the initial charge, ΔQ chg ΔQ represents the change in the amount of electricity charged within a statistical time interval. dsg Q is the value of the change in discharge charge within a statistical time interval. max This represents the current maximum actual capacity of the battery.

[0066] For example, the battery management system collects and processes the current I.

[0067] When I is the charging direction, the charging current I chg =I, discharge current I dsg =0,

[0068] When I is in the discharge direction, the discharge current I dsg =I, charging current I chg =0.

[0069] Change in charge from time t0 to time t1

[0070] Change in discharge charge from time t0 to time t1

[0071] The charge Q at time t1 t1 =Q t0 +△Q chg +△Q dsg Q t1 Q t0 These represent the battery levels at time t1 and t0, respectively.

[0072] SOC at time t1 t1 =Q t1 / Q max .

[0073] Subsequently, the real-time current, real-time temperature, and real-time voltage of the sodium-ion battery are monitored in real time through the sodium-ion battery management system.

[0074] When the real-time current remains at zero for a preset duration, OCV calibration is initiated. Before performing OCV calibration, it is necessary to confirm that the battery system is stable. Based on battery characteristics, this embodiment considers that the battery is essentially completely stationary after 2 hours of rest.

[0075] That is, when it is determined that the real-time current I = 0 for 2 hours, SOC calibration is initiated.

[0076] First, in step 103, based on the current real-time temperature, the first curve and the second curve with the smallest difference in test temperature are selected from the preset curve library; wherein the current real-time temperature is between the test temperatures of the first curve and the second curve.

[0077] The preset curve library stores multiple curves reflecting the mapping relationship between open-circuit voltage and SOC. Any two curves are obtained by testing at different test temperatures, which are the temperatures of sodium-ion batteries. In practice, curves at different battery temperatures are pre-tested in a laboratory using specialized equipment with actual battery cell samples. Figure 3 is a schematic diagram of the OCV-SOC curve of a sodium-ion battery in an embodiment of this application. As shown in Figure 3, this curve displays the mapping relationship between open-circuit voltage and SOC.

[0078] Then, in step 104, the linear difference of SOC is calculated multiple times using the current real-time voltage, the current real-time temperature, the first curve, and the second curve to obtain the SOC corresponding to the current real-time temperature.

[0079] In one embodiment, the SOC is obtained by repeatedly calculating the linear difference between the current real-time voltage, the current real-time temperature, the first curve, and the second curve to obtain the SOC corresponding to the current real-time temperature. This may include:

[0080] By using the current real-time voltage, the first curve, and the second curve, linear difference calculation is performed to obtain the first SOC and the second SOC corresponding to the current real-time voltage on the first curve and the second curve, respectively.

[0081] By using the current real-time temperature, the test temperature of the first curve, the first SOC, and the test temperature and second SOC of the second curve, a linear difference calculation is performed to obtain the SOC corresponding to the current real-time temperature.

[0082] The process of calculating the linear difference between the current real-time voltage, the first curve, and the second curve to obtain the first SOC and the second SOC corresponding to the current real-time voltage on the first and second curves, respectively, may include:

[0083] Using the current real-time voltage, determine the two points on the first curve and the second curve where the difference in open-circuit voltage is the smallest; the current real-time voltage is between the open-circuit voltages of the two points.

[0084] By using the open-circuit voltage and SOC at two points on the first curve to perform linear difference calculation, the first SOC corresponding to the current real-time voltage on the first curve is obtained. Similarly, by using the open-circuit voltage and SOC at two points on the second curve to perform linear difference calculation, the second SOC corresponding to the current real-time voltage on the second curve is obtained.

[0085] For example, in the preset curve library, the OCV-SOC curve number is n, the test temperature of the nth OCV-SOC curve is Tab_T(n), the voltage at the mth point in the nth table is Tab_V(n,m), the SOC is Tab_SOC(n,m), and the mapping relationship is Tab_Soc(n,m)=f(n,Tab_V(n,m)).

[0086] During implementation, based on the current real-time temperature T, the closest OCV-SOC curve is searched in the preset curve library. When Tab_T(n)≤T<Tab_T(n+1) is satisfied, the two tables n and n+1 are selected for calibration.

[0087] Then, using the current real-time voltage V, determine the two points on the first curve and the second curve where the difference in open-circuit voltage is the smallest; the current real-time voltage is between the open-circuit voltages of the two points.

[0088] That is, when Tab_V(n,m0)≤V<Tab_V(n,m0+1), select points m0 and m0+1 as adjacent points of voltage in OCV table n;

[0089] When Tab_V(n+1,m1)≤V<Tab_V(n+1,m1+1), select points m1 and m1+1 as adjacent points of voltage in OCV table n+1.

[0090] Then, the open-circuit voltage and SOC at two points on the first curve are used to perform linear difference calculation to obtain the first SOC corresponding to the current real-time voltage on the first curve. The open-circuit voltage and SOC at two points on the second curve are used to perform linear difference calculation to obtain the second SOC corresponding to the current real-time voltage on the second curve.

[0091] Taking the curve on the nth table as an example, the distance (i.e. voltage difference) between the current real-time voltage V and Tab_V(n,m0) is V-Tab_V(n,m0);

[0092] The distance between Tab_V(n,m0) and Tab_V(n,m0+1) is Tab_V(n,m0+1)-Tab_V(n,m0), denoted as △Tab_V(n,m0);

[0093] The distance between Tab_Soc(n,m0) and Tab_Soc(n,m0+1) is Tab_Soc(n,m0+1)-Tab_Soc(n,m0), denoted as △Tab_Soc(n,m0).

[0094] Assuming the SOC difference ratio is the same as the voltage difference ratio, based on the difference algorithm,

[0095] Similarly, we can conclude that:

[0096] Finally, by using the current real-time temperature, the test temperature of the first curve, the first SOC, and the test temperature of the second curve, the second SOC, a linear difference calculation is performed to obtain the SOC corresponding to the current real-time temperature.

[0097] The distance between the current real-time temperature T and Tab_T(n) is T-Tab_T(n);

[0098] The distance between Tab_T(n) and Tab_T(n+1) is Tab_T(n+1)-Tab_T(n), denoted as △Tab_T(n);

[0099] SOC n With SOC n+1 The distance is SOCn+1-SOCn, denoted as △SOCn;

[0100] Calculated based on the temperature difference:

[0101] Real-time temperature T corresponds to

[0102] Finally, in step 105, the real-time SOC is corrected using the SOC corresponding to the current real-time temperature.

[0103] To further improve the accuracy of the State of Charge (SOC) of sodium-ion batteries, in one embodiment, after monitoring the real-time current, real-time temperature, and real-time voltage of the sodium-ion battery, the method for calculating the state of charge of the sodium-ion battery may further include:

[0104] When the sodium-ion battery is in charging mode, when a charging cut-off event is triggered, the real-time SOC is corrected to 100%; the charging cut-off event includes a real-time current of zero.

[0105] When the sodium-ion battery is in discharge mode, when a discharge cutoff event is triggered, the real-time SOC is corrected to 0%; the discharge cutoff event includes a real-time current of zero.

[0106] In this example, a full-fill-discharge calibration is performed.

[0107] Figure 4 is a schematic diagram of the current reduction process of the sodium-ion battery system in this embodiment of the application. As shown in Figure 4, the horizontal axis represents time information and the vertical axis represents current. During normal use of the sodium-ion battery, at the end of charging and discharging, the battery management system will control the system to reduce the current. After the current reduction is completed and the cutoff is reached, the charging and discharging can be considered to have ended normally. At this time, the current real-time SOC of the sodium-ion battery system can be accurately calibrated.

[0108] Under charging conditions:

[0109] When the charging cutoff event is triggered... chg =0, indicating that the full charge event has been triggered and SOC = 100%.

[0110] Under discharge conditions:

[0111] When the discharge cutoff event is triggered &&I dsg =0, indicating that the full-load event has been triggered, SOC = 0%.

[0112] Another scenario exists where the charging / discharging equipment operates in manual mode, uncontrolled by the battery system. In this case, the terminal will not reduce current according to the battery management system's control, and calibration should be performed based on the system's protection point. However, since the current is unstable at the cutoff point, it cannot be used as a basis for capacity estimation.

[0113] Under charging conditions:

[0114] When overvoltage protection is triggered && trigger time I chg <Para 预设最小电流 SOC = 100%.

[0115] Under discharge conditions:

[0116] When undervoltage protection is triggered && trigger time I dsg <Para 预设最小电流 SOC = 0%.

[0117] To further improve the accuracy of the State of Charge (SOC) of sodium-ion batteries, embodiments of this application perform maximum capacity calibration. In one embodiment, after monitoring the real-time current, real-time temperature, and real-time voltage of the sodium-ion battery, the method for calculating the state of charge of the sodium-ion battery may further include:

[0118] Record the state of charge (SOC) at the first time point t1. t1 Battery Q t1 ;

[0119] When the sodium-ion battery is operating normally at the second time point t2, the state of charge (SOC) is recorded. t2 Battery Q t2 Among them, SOC t2 With SOC t1The difference reaches the set threshold;

[0120] When t1 to t2 is the discharge process, the latest maximum capacitance is determined by the following formula: Q' max =(Q t2 -Q t1 ) / (SOC t1 -SOC t2 );

[0121] When the period from t1 to t2 is the charging process, the latest maximum capacity is determined by the following formula: Q' max =(Q t2 -Q t1 ) / (SOC t2 -SOC t1 );

[0122] In the formula, Q' max This is the latest maximum capacity.

[0123] In one embodiment, the selection of the two time points t1 and t2 is credible, i.e., the SOC at each time point is within the pre-examination range, for example, between 20% and 80%.

[0124] After determining the latest maximum capacity, the state of charge (SOC) calculation of the sodium-ion battery in Figure 1 can also include: calibrating the real-time SOC using the latest maximum capacity.

[0125] When triggering OCV calibration or current-controlled upper and lower limit calibration, the status of the recorded point includes the current SOC, charging capacity, and discharging capacity of the point.

[0126] If the SOC difference between the first and second points exceeds 50%, and the operating status is normal between the two records, with no warnings and a single direction of operating current, then capacity estimation can be performed.

[0127] Let point 1 be t1 and point 2 be t2, then the SOC is recorded. t1 SOC t2 Q chgt1 Q chgt2 Q dsgt1 Q dsgt2 .

[0128] If the process from point t1 to point t2 is a discharge process:

[0129] So

[0130] If the process from point t1 to point t2 is a charging process:

[0131] So

[0132] In one embodiment, if there is both charging and discharging between time point t1 and time point t2, then the calibration opportunity is abandoned to avoid introducing a large error.

[0133] In summary, the sodium-ion battery state-of-charge (SOC) calculation method in this application mainly includes a real-time SOC statistics section, an OCV calibration section, a full charge / discharge calibration section, and a capacity estimation section.

[0134] When calculating the State of Charge (SOC) of a sodium-ion battery, the main bases include the SOC corresponding to the voltage value of each individual cell and the change in charge calculated based on the detected current. When the battery undergoes full charging and full discharging operations according to system conditions, it can be calibrated as fully charged and depleted, respectively. The accumulated charging and discharging capacity during these processes can be considered the battery's capacity. The proportion of the change in charge to the total capacity during battery use is the change in SOC. However, if the battery operates in the intermediate range for a long time without full charging and discharging, the accuracy of the SOC will gradually decrease due to self-discharge and accumulated errors. Sodium-ion batteries inherently have a wide voltage range and a clear correlation between battery voltage and charge; therefore, this application uses a voltage-to-charge method for correction. Long-term static voltage stability is high, with few interference factors, and can serve as a highly reliable calibration benchmark for SOC correction.

[0135] The power statistics section uses current values ​​acquired by current sensors and related acquisition algorithms. These values ​​are integrated based on time data obtained from a timer to determine the change in battery power. This change in power is categorized into charging power and discharging power, depending on the charging and discharging states. The ratio of charging power to total battery capacity represents the increase in battery SOC (State of Charge), while the ratio of discharging power to total battery capacity represents the decrease in SOC. The total charging power is the amount of power charged during the process of going from empty to fully charged, and the total discharging power is the amount of power discharged during the process of going from fully charged to empty. Discharging power is the battery's capacity in a general sense; charging power will always exceed discharging power.

[0136] Full charge / discharge is a special operating state, representing the battery's maximum usable range and the most stable method for determining State of Charge (SOC). This method differs from SOC determination during operation. Full charge / discharge generally has two operating conditions: a controlled system state and an uncontrolled system state. When the system is controlled, at the end of the charge / discharge cycle, the battery system should reduce current and cut off according to the battery management system's preset scheme. When a cutoff action occurs, the battery system can be considered fully charged / discharged. When the system is uncontrolled but within the normal allowable operating range, the full charge / discharge is determined by triggering the cutoff protection. The cutoff protection is slightly more lenient than the active cutoff action to accommodate situations where the system is uncontrolled and triggers the cutoff protection at the maximum allowable power.

[0137] OCV calibration refers to the method of using open-circuit resting voltage for SOC calibration. Compared to lithium iron phosphate batteries, which have the largest market share, sodium-ion batteries have a very obvious voltage-SOC mapping relationship, making voltage-mapped SOC calibration very suitable. During use, sodium-ion batteries experience polarization, which means that when the battery transitions from operation to resting, the battery voltage cannot immediately match the long-term resting state. As the resting time gradually increases, the battery voltage will gradually approach the long-term resting voltage.

[0138] Figure 5 is another specific example of the sodium-ion battery state-of-charge (SOC) measurement method in this application. As can be seen from Figure 5, the battery capacity varies significantly at different temperatures; the capacity decreases significantly at low temperatures and increases significantly at high temperatures. Therefore, the OCV calibration method in this application requires the system to be without current for a period of time. From multiple OCV-SOC correspondence tables, a table with a similar temperature is selected, and then a point with a voltage similar to the current sodium-ion battery is selected. The difference is then calculated to obtain the corresponding SOC value, thus effectively improving the accuracy of OCV calibration.

[0139] This application also provides a sodium-ion battery state-of-charge (SOC) measurement device, as described in the following embodiments. Since the principle behind this device is similar to the SOC measurement method for sodium-ion batteries, its implementation can be referenced from the implementation of the SOC measurement method for sodium-ion batteries; repeated details will not be elaborated further.

[0140] Figure 6 is a schematic diagram of the sodium-ion battery state-of-charge measurement device in an embodiment of this application. As shown in Figure 5, the device 600 includes:

[0141] The power statistics module 601 is used to output the real-time state of charge (SOC) of sodium-ion batteries based on the current integration method and the real-time current and time information.

[0142] The data acquisition module 602 is used to monitor the real-time current, real-time temperature and real-time voltage of the sodium-ion battery;

[0143] The OCV calibration module 603 is used to select the first and second curves with the smallest difference in test temperatures from a preset curve library when the real-time current is continuously zero for a preset duration. The preset curve library stores multiple curves reflecting the mapping relationship between open-circuit voltage and SOC. Any two curves are obtained by testing at different test temperatures, which are the temperatures of sodium-ion batteries. The current real-time temperature is between the test temperatures of the first and second curves. The linear difference of SOC is calculated multiple times using the current real-time voltage, current real-time temperature, first curve, and second curve to obtain the SOC corresponding to the current real-time temperature. The real-time SOC is corrected using the SOC corresponding to the current real-time temperature.

[0144] In one embodiment, the power consumption statistics module 601 is specifically used for:

[0145] Get the initial battery level;

[0146] The charge is obtained by integrating the real-time current and the time interval.

[0147] The change in charge is determined based on the current charging / discharging direction and the amount of charge. The current charging / discharging direction includes the charging direction and the discharging direction. The charge is positive when charging and negative when discharging.

[0148] The real-time State of Charge (SOC) is determined based on the initial charge, the change in charge, and the maximum capacity.

[0149] In one embodiment, the power consumption statistics module 601 is specifically used for:

[0150] The real-time SOC is determined using the following formula, based on the initial SOC, the change in charge, and the maximum capacity: SOC 实时 =(Q t0 +△Q chg +△Q dsg ) / Q max ;

[0151] In the formula, SOC 实时 For real-time SOC, Q t0 For the initial charge, ΔQ chg ΔQ represents the change in the amount of electricity charged within a statistical time interval. dsg Q is the value of the change in discharge charge within a statistical time interval. max This represents the current maximum electrical capacity.

[0152] In one embodiment, the OCV calibration module 603 is specifically used for:

[0153] By using the current real-time voltage, the first curve, and the second curve, linear difference calculation is performed to obtain the first SOC and the second SOC corresponding to the current real-time voltage on the first curve and the second curve, respectively.

[0154] By using the current real-time temperature, the test temperature of the first curve, the first SOC, and the test temperature and second SOC of the second curve, a linear difference calculation is performed to obtain the SOC corresponding to the current real-time temperature.

[0155] In one embodiment, the OCV calibration module 603 is specifically used for:

[0156] Using the current real-time voltage, determine the two points on the first curve and the second curve where the difference in open-circuit voltage is the smallest; the current real-time voltage is between the open-circuit voltages of the two points.

[0157] By using the open-circuit voltage and SOC at two points on the first curve to perform linear difference calculation, the first SOC corresponding to the current real-time voltage on the first curve is obtained. Similarly, by using the open-circuit voltage and SOC at two points on the second curve to perform linear difference calculation, the second SOC corresponding to the current real-time voltage on the second curve is obtained.

[0158] In one embodiment, the device 600 further includes a full charge / discharge calibration module, used for:

[0159] After the data acquisition module 601 monitors the real-time current, real-time temperature and real-time voltage of the sodium-ion battery, when the sodium-ion battery is in charging condition, when a charging cut-off event is triggered, the real-time SOC is corrected to 100%; the charging cut-off event includes a real-time current of zero.

[0160] When the sodium-ion battery is in discharge mode, when a discharge cutoff event is triggered, the real-time SOC is corrected to 0%; the discharge cutoff event includes a real-time current of zero.

[0161] In one embodiment, the device 600 further includes: a capacity estimation module, used for:

[0162] Record the state of charge (SOC) at the first time point t1. t1 Battery Q t1 ;

[0163] When the sodium-ion battery is operating normally at the second time point t2, the state of charge (SOC) is recorded. t2 Battery Q t2 Among them, SOC t2 With SOC t1 The difference reaches the set threshold;

[0164] When t1 to t2 is the discharge process, the latest maximum capacitance is determined by the following formula: Q' max =(Q t2 -Q t1 ) / (SOC t1 -SOC t2 );

[0165] When the period from t1 to t2 is the charging process, the latest maximum capacity is determined by the following formula: Q' max =(Q t2 -Q t1 ) / (SOC t2 -SOC t1 );

[0166] In the formula, Q' max This is the latest maximum capacity.

[0167] In one embodiment, the device 600 further includes: a capacity calibration module, used for:

[0168] After the capacity estimation module determines the latest maximum capacity, the real-time SOC is calibrated using the latest maximum capacity.

[0169] This application also provides 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 implements the above-described method for calculating the state of charge of a sodium-ion battery.

[0170] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for calculating the state of charge of a sodium-ion battery.

[0171] This application also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described method for calculating the state of charge of a sodium-ion battery.

[0172] In this embodiment, the real-time SOC to be calibrated is first output based on the current integration method. SOC calibration is initiated when the real-time current remains at zero for a preset duration. Considering the influence of battery temperature on SOC, multiple curves are obtained beforehand at different sodium-ion battery temperatures. During calibration, the linear difference of SOC is calculated multiple times using the current real-time voltage, current real-time temperature, the first curve, and the second curve to obtain the SOC corresponding to the current real-time temperature, thus obtaining a more accurate SOC. This more accurate SOC is then used to calibrate the aforementioned real-time SOC. Compared with existing technical solutions, this embodiment can significantly improve the accuracy of sodium-ion battery SOC measurement.

[0173] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0174] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more flowchart illustrations and / or one or more block diagrams.

[0175] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0176] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0177] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for calculating the state of charge of a sodium-ion battery, characterized in that, include: Based on the current integration method, the real-time state of charge (SOC) of sodium-ion batteries is output using the real-time current and time information. Monitor the real-time current, real-time temperature, and real-time voltage of sodium-ion batteries; When the real-time current remains at zero for a preset duration, the first and second curves with the smallest difference in test temperature are selected from the preset curve library based on the current real-time temperature. The preset curve library stores multiple curves reflecting the mapping relationship between open-circuit voltage and SOC. Any two curves are obtained by testing at different test temperatures, where the test temperature is the temperature of the sodium-ion battery; the current real-time temperature is between the test temperatures of the first curve and the second curve. By using the current real-time voltage, current real-time temperature, first curve and second curve to perform linear difference calculation of SOC multiple times, the SOC corresponding to the current real-time temperature is obtained; as well as The real-time SOC is corrected using the SOC corresponding to the current real-time temperature.

2. The method of claim 1, wherein the method is performed by a processor of a battery management system. Based on the current integration method, the real-time SOC (State of Charge) of a sodium-ion battery is output using real-time current and time information, including: Get the initial battery level; The charge is obtained by integrating the real-time current and the time interval. The change in charge is determined based on the current charging / discharging direction and the amount of charge; the current charging / discharging direction includes both the charging and discharging directions, with the charge being positive during charging and negative during discharging; and... The real-time State of Charge (SOC) is determined based on the initial charge, the change in charge, and the maximum capacity.

3. The method of claim 2, wherein the method further comprises: Based on the initial SOC, the change in charge, and the maximum capacity, the real-time SOC is determined, including: The real-time SOC is determined using the following formula, based on the initial SOC, the change in charge, and the maximum capacity: SOC 实时 = (Q t0 + ΔQ chg + ΔQ dsg ) / Q max ; In the formula, SOC 实时 is the real-time SOC, Q t0 is the initial electric quantity, AQ chg is the change value of the electric quantity charged in the statistical time interval, AQ dsg is the change value of the electric quantity discharged in the statistical time interval, Q max is the maximum electric capacity.

4. The method of claim 1, wherein the method is performed by a processor. By repeatedly calculating the linear difference of SOC using the current real-time voltage, current real-time temperature, the first curve, and the second curve, the SOC corresponding to the current real-time temperature is obtained, including: By performing linear interpolation calculations using the current real-time voltage, the first curve, and the second curve, the first SOC and the second SOC corresponding to the current real-time voltage on the first and second curves, respectively, are obtained; and By using the current real-time temperature, the test temperature of the first curve, the first SOC, and the test temperature and second SOC of the second curve, a linear difference calculation is performed to obtain the SOC corresponding to the current real-time temperature.

5. The method of claim 4, wherein the method further comprises: By performing linear interpolation calculations using the current real-time voltage, the first curve, and the second curve, the first SOC and the second SOC corresponding to the current real-time voltage on the first curve and the second curve, respectively, are obtained, including: Using the current real-time voltage, determine the two points on the first curve and the second curve where the difference in open-circuit voltage is minimized; the current real-time voltage lies between the open-circuit voltages at these two points; and By performing linear difference calculation using the open-circuit voltage and SOC at the two points on the first curve, the first SOC corresponding to the current real-time voltage on the first curve is obtained. Similarly, by performing linear difference calculation using the open-circuit voltage and SOC at the two points on the second curve, the second SOC corresponding to the current real-time voltage on the second curve is obtained.

6. The method of claim 1, wherein the method is performed by a processor of a battery management system. After monitoring the real-time current, real-time temperature, and real-time voltage of the sodium-ion battery, the following is also included: When the sodium-ion battery is charging, if a charging cutoff event is triggered, the real-time SOC is corrected to 100%; the charging cutoff event includes a real-time current of zero; and When the sodium-ion battery is in discharge mode, when a discharge cutoff event is triggered, the real-time SOC is corrected to 0%; the discharge cutoff event includes a real-time current of zero.

7. The method of claim 3, wherein the method comprises: After monitoring the real-time current, real-time temperature, and real-time voltage of the sodium-ion battery, the following is also included: record the state of charge SOC at a first time point t1 t1 , the amount of electricity Q t1 ; When the sodium-ion battery normally works to a second time point t2, the state of charge SOC t2 , the electric quantity Q t2 ; wherein the difference between SOC t2 and SOC t1 reaches a set threshold value; When t1 to t2 is the discharge process, the latest maximum capacity is determined according to the following formula: Q' max = (Q t2 - Q t1 ) / (SOC t1 - SOC t2 ); When t1 to t2 is the charging process, the latest maximum capacity is determined according to the following formula: Q' max = (Q t2 - Q t1 ) / (SOC t2 - SOC t1 ); In the formula, Q max is the latest maximum capacitance.

8. The method of claim 7, wherein the method further comprises: After determining the latest maximum capacity, it also includes: Real-time SOC is calibrated using the latest maximum capacitance.

9. A sodium-ion battery state-of-charge measurement device, characterized in that, include: The power statistics module is used to output the real-time state of charge (SOC) based on the real-time current and time information of the sodium-ion battery using the current integration method. The data acquisition module is used to monitor the real-time current, real-time temperature, and real-time voltage of the sodium-ion battery. as well as The OCV calibration module is used to select the first and second curves with the smallest difference in test temperature from the preset curve library based on the current real-time temperature when the real-time current is continuously zero for a preset duration. The preset curve library stores multiple curves reflecting the mapping relationship between open-circuit voltage and SOC. Any two curves are obtained by testing at different test temperatures, where the test temperature is the temperature of the sodium-ion battery. The current real-time temperature is between the test temperatures of the first and second curves. The linear difference of SOC is calculated multiple times using the current real-time voltage, current real-time temperature, first curve, and second curve to obtain the SOC corresponding to the current real-time temperature. The real-time SOC is corrected using the SOC corresponding to the current real-time temperature.

10. The sodium-ion battery state-of-charge estimation apparatus of claim 9, wherein, The power consumption statistics module is specifically used for: Get the initial battery level; The charge is obtained by integrating the real-time current and the time interval. The change in charge is determined based on the current charging / discharging direction and the amount of charge; the current charging / discharging direction includes both the charging and discharging directions, with the charge being positive during the charging direction and negative during the discharging direction; and... The real-time State of Charge (SOC) is determined based on the initial charge, the change in charge, and the maximum capacity.

11. The sodium-ion battery state-of-charge estimation apparatus of claim 10, wherein, The power consumption statistics module is specifically used for: The real-time SOC is determined using the following formula, based on the initial SOC, the change in charge, and the maximum capacity: SOC 实时 = (Q t0 +△Q chg +△Q dsg ) / Q max ; SOC 实时 Q is the real-time SOC t0 Q is the initial charge chg Q is the change in charge value charged during the statistical time interval dsg Q is the change in charge value discharged during the statistical time interval max Q is the maximum capacity 12. The sodium-ion battery state-of-charge estimation apparatus of claim 9, wherein, The OCV calibration module is specifically used for: By using the current real-time voltage, the first curve, and the second curve, linear difference calculation is performed to obtain the first SOC and the second SOC corresponding to the current real-time voltage on the first curve and the second curve, respectively. as well as By using the current real-time temperature, the test temperature of the first curve, the first SOC, and the test temperature and second SOC of the second curve, a linear difference calculation is performed to obtain the SOC corresponding to the current real-time temperature.

13. The sodium-ion battery state-of-charge estimation apparatus of claim 12, wherein, The OCV calibration module is specifically used for: Using the current real-time voltage, determine the two points on the first curve and the second curve where the difference in open-circuit voltage is the smallest; the current real-time voltage is between the open-circuit voltages of the two points. as well as By performing linear difference calculation using the open-circuit voltage and SOC at the two points on the first curve, the first SOC corresponding to the current real-time voltage on the first curve is obtained. Similarly, by performing linear difference calculation using the open-circuit voltage and SOC at the two points on the second curve, the second SOC corresponding to the current real-time voltage on the second curve is obtained.

14. The sodium-ion battery state-of-charge estimation apparatus of claim 9, wherein Also includes: Full charge / discharge calibration module, used for: After the data acquisition module monitors the real-time current, real-time temperature, and real-time voltage of the sodium-ion battery, when the sodium-ion battery is in charging condition, when a charging cut-off event is triggered, the real-time SOC is corrected to 100%; the charging cut-off event includes a real-time current of zero. as well as When the sodium-ion battery is in discharge mode, when the discharge cutoff event is triggered, the real-time SOC is corrected to 0%. Discharge cutoff events include real-time current being zero.

15. The sodium-ion battery state-of-charge estimation apparatus of claim 11, wherein, Also includes: The capacity estimation module is used for: record the state of charge SOC at a first time point t1 t1 , the amount of electricity Q t1 ; When the sodium-ion battery is normally working to a second time point t2, the state of charge SOC t2 , the electric quantity Q t2 ; wherein the SOC t2 reaches a set threshold value from the SOC t1 of the battery. When t1 to t2 is the discharge process, the latest maximum capacity is determined according to the following formula: Q' max = (Q t2 - Q t1 ) / (SOC t1 - SOC t2 ); When t1 to t2 is the charging process, the latest maximum capacity is determined according to the following formula: Q' max = (Q t2 - Q t1 ) / (SOC t2 - SOC t1 ); In the formula, Q max is the latest maximum capacitance.

16. The sodium-ion battery state-of-charge estimation apparatus of claim 15, wherein, It also includes: a capacity calibration module, used for: After the capacity estimation module determines the latest maximum capacity, the real-time SOC is calibrated using the latest maximum capacity.

17. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the sodium-ion battery state-of-charge calculation method according to any one of claims 1 to 8.

18. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method for calculating the state of charge of a sodium-ion battery according to any one of claims 1 to 8.

19. A computer program product, characterised in that, The computer program product includes a computer program that, when executed by a processor, implements the sodium-ion battery state-of-charge calculation method according to any one of claims 1 to 8.

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