Sodium-ion battery pack equalization method and device based on battery cell monomer capacity correction

Abstract

The invention discloses a sodium ion battery pack equalization method and device based on battery cell monomer capacity correction, and the method comprises the steps: determining a charging reference battery cell and a discharging reference battery cell in a target sodium ion battery pack, and collecting the voltage, current, temperature and charge-discharge cycle times of each monomer battery cell in the target sodium ion battery pack in real time; based on the voltage, the current, the temperature and the number of charge-discharge cycles, determining the actual available capacity of the single cell; determining the residual charging time difference between each residual single cell and the charging reference cell, and determining the residual chargeable capacity of the corresponding residual single cell based on the residual charging time difference; determining the residual discharge time difference between each residual single cell and the discharge reference cell, and determining the residual dischargeable capacity of the residual single cells based on the residual discharge time difference and the actual available capacity; and carrying out capacity equalization on the target sodium ion battery pack based on the residual chargeable capacity and the residual dischargeable capacity of the residual single battery cells.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of sodium ion battery packs, in particular to a sodium ion battery pack equalization method and device based on cell monomer capacity correction. BACKGROUND

[0002] A sodium ion battery is a new type of high-performance battery, which has the advantages of high energy density, good safety, rich materials and the like, is regarded as an important development direction in the future fields of electric vehicles, energy storage systems and the like, and a sodium ion battery pack is a battery collection composed of multiple sodium ion battery monomers through series connection, parallel connection or series-parallel connection combination. The sodium ion battery pack functions to provide required electric energy for various devices and systems. Compared with a single sodium ion battery monomer, the battery pack can provide higher voltage and greater capacity to meet the power and energy requirements of power supply in different application scenarios. Since the sodium ion battery pack is composed of multiple sodium ion battery monomers, after the batteries in the battery pack are used for a period of time, due to the inconsistency in the battery manufacturing process, initial capacity and the like, the capacity difference between the batteries is caused after use. The inconsistency of the battery monomers causes more batteries to be unable to charge sufficient electric quantity or discharge sufficient capacity, so that the overall capacity is sharply reduced, thereby causing the effective service life of the battery pack to be seriously reduced, and the reliability and safety of the battery pack are greatly reduced in long-term operation. Therefore, it is necessary to equalize the capacity of each battery in the battery pack, so as to maintain the consistency of the entire battery pack and improve the service life of the battery.

[0003] At present, in the capacity equalization process of the sodium ion battery pack, the electric energy of the capacity excessive battery is usually consumed through a resistor. However, this capacity consumption mode has low energy utilization rate and has the problem of energy waste. Meanwhile, the capacity consumption through the resistor also causes the risk of high temperature of the battery, thereby reducing the service life of the sodium ion battery pack. SUMMARY

[0004] The application provides a sodium ion battery pack equalization method and device based on cell monomer capacity correction, which can improve the energy utilization rate of the sodium ion battery pack, avoid the high temperature of the battery pack, and thereby improve the service life of the sodium ion battery pack.

[0005] According to a first aspect of the application, a sodium ion battery pack equalization method based on cell monomer capacity correction is provided, which comprises the following steps: In response to a capacity equalization signal of a target sodium ion battery pack, a charging reference cell and a discharging reference cell are determined in each monomer cell of the target sodium ion battery pack, and the voltage, current, temperature and charging and discharging cycle number of each monomer cell in the target sodium ion battery pack are collected in real time. Based on the voltage, current, temperature, and charge / discharge cycle number, the actual usable capacity of the corresponding single cell is determined. The actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining single cells. The remaining single cells are the single cells in the target sodium-ion battery pack after removing the charging reference cell and the discharging reference cell. Determine the remaining charging time difference between each remaining single cell and the charging reference cell, and based on the remaining charging time difference, the actual available capacity of each remaining single cell, and the actual available capacity of the charging reference cell, determine the remaining rechargeable capacity of the corresponding remaining single cell. Determine the remaining discharge time difference between each remaining single cell and the discharge reference cell, and based on the remaining discharge time difference, the actual usable capacity of each remaining single cell, and the actual usable capacity of the discharge reference cell, determine the remaining dischargeable capacity of the corresponding remaining single cell. Based on the remaining rechargeable and dischargeable capacity of each remaining individual cell, the capacity of each individual cell in the target sodium-ion battery pack is balanced.

[0006] Optionally, a charging reference cell and a discharging reference cell are determined in each individual cell of the target sodium-ion battery pack, including: The target sodium-ion battery pack is charged with constant current. The dynamic charging voltage of each individual cell is collected at a preset charging time interval. The individual cell whose dynamic charging voltage reaches the preset charging cutoff voltage is selected as the charging reference cell. The target sodium-ion battery pack is subjected to constant current discharge. The dynamic discharge voltage of each individual cell is collected at a preset discharge time interval. The individual cell whose dynamic discharge voltage reaches the preset discharge cutoff voltage is selected as the discharge reference cell.

[0007] Optionally, determining the actual usable capacity of a single battery cell based on the voltage, current, temperature, and charge / discharge cycle count includes: Multiple sodium-ion battery cell samples were identified, and multiple sample temperature points were set in a temperature chamber. Based on each sample temperature point, the sodium-ion battery cell samples were subjected to cyclic charge-discharge operations at various charge-discharge rates in the temperature chamber until the cell capacity of each sodium-ion battery cell sample decayed to meet the requirements. The actual cell capacity of each sodium-ion battery cell sample under different sample temperatures, different sample currents, and different sample voltages in each cycle of charge-discharge operation was recorded. Based on the actual capacity of each sodium ion cell sample under different temperatures, currents, and voltages during each charge-discharge cycle, a pre-defined capacity prediction model is constructed. The voltage, current, temperature, and charge / discharge cycle count of each individual cell are input into the preset capacity prediction model to predict the actual usable capacity of each individual cell.

[0008] Optionally, determining the remaining charging time difference between each remaining individual cell and the charging reference cell includes: Based on the relationship between charging time and charging voltage during the charging process of the reference cell before and after the voltage plateau period, a linear function for charging before the voltage plateau period and a linear function for charging after the voltage plateau period are constructed accordingly. The starting charging time of the charging reference cell before the voltage plateau period is determined. Based on the starting charging time, the starting charging voltage of the plateau period is determined using the charging linear function before the plateau period. The ending charging time of the charging reference cell after the voltage plateau period is determined. Based on the ending charging time, the ending charging voltage of the plateau period is determined using the charging linear function after the plateau period. Determine the charging cutoff voltage for each remaining individual battery cell, and determine the charging time for the reference battery cell to reach the preset charging cutoff voltage during constant current charging. Based on the start charging time, the end charging time, the start charging voltage of the plateau period, and the end charging voltage of the plateau period, the charging time corresponding to the voltage at the charging cutoff point is determined. The charging time and the charging time The difference between them is taken as the remaining charging time difference. ; Determining the remaining discharge time difference between each remaining individual cell and the discharge reference cell includes: Based on the relationship between the discharge time and discharge voltage of the discharge reference cell before and after the voltage plateau period, a linear function for discharge before the voltage plateau period and a linear function for discharge after the voltage plateau period are constructed accordingly. The starting discharge time of the discharge reference cell before the voltage plateau period is determined. Based on the starting discharge time, the starting discharge voltage of the plateau period is determined using the discharge linear function before the plateau period. The ending discharge time of the discharge reference cell after the voltage plateau period is determined. Based on the ending discharge time, the ending discharge voltage of the plateau period is determined using the discharge linear function after the plateau period. Determine the discharge cutoff voltage for each remaining individual cell, and determine the discharge duration for the reference cell to reach the preset discharge cutoff voltage during constant current discharge. Based on the start discharge time, the end discharge time, the start discharge voltage of the plateau period, and the end discharge voltage of the plateau period, the discharge time corresponding to the discharge cutoff voltage is determined. The discharge duration and the discharge time The difference between them is taken as the remaining discharge time difference. .

[0009] Optionally, determining the remaining rechargeable capacity of the corresponding remaining individual cell based on the remaining charging time difference, the actual usable capacity of each remaining individual cell, and the actual usable capacity of the charging reference cell includes: Determine the constant current charging current of the target sodium-ion battery pack. and charging efficiency ; Based on the remaining charging time difference Each remaining single cell Actual available capacity The actual usable capacity of the charging reference cell Determine the corresponding remaining individual battery cells Remaining rechargeable capacity ,in, .

[0010] Optionally, determining the remaining discharge capacity of the corresponding remaining single cell based on the remaining discharge time difference, the actual usable capacity of each remaining single cell, and the actual usable capacity of the discharge reference cell includes: Determine the constant current discharge current of the target sodium-ion battery pack. and discharge efficiency ; Based on the remaining discharge time difference Each remaining single cell Actual available capacity The actual usable capacity of the discharge reference cell Determine the corresponding remaining individual battery cells Remaining discharge capacity ,in, .

[0011] Optionally, the process of balancing the capacity of individual cells in the target sodium-ion battery pack based on the remaining rechargeable and dischargeable capacity of each remaining cell includes: The sum of the remaining rechargeable capacity of each remaining individual cell and the sum of the remaining dischargeable capacity of each remaining individual cell are determined. The minimum value between the sum of the remaining rechargeable capacity and the sum of the remaining dischargeable capacity is taken as the current available capacity of the target sodium-ion battery pack. Based on the actual factory capacity of the target sodium-ion battery pack, a preset capacity threshold is determined. ; Based on the current available capacity and the preset capacity threshold Determine whether the target sodium-ion battery pack meets the capacity balance condition between individual cells; If the target sodium-ion battery pack meets the capacity balancing condition, then the actual factory capacity and current discharge capacity of the target sodium-ion battery pack are determined, and the balancing capacity is determined based on the actual factory capacity and current discharge capacity of the target sodium-ion battery pack. Based on the balanced capacity and the remaining rechargeable capacity of each remaining cell, low-capacity cells and high-capacity cells are identified in each remaining cell. Based on the balanced capacity and the remaining rechargeable capacity, a capacity transfer amount is determined. Based on the capacity transfer amount, the capacity in the high-capacity cell is transferred to the low-capacity cell. Based on the balanced capacity and the remaining dischargeable capacity of each remaining cell, the cell whose capacity needs to be released is determined in each remaining cell. Based on the balanced capacity and the remaining dischargeable capacity, the capacity release amount is determined. Based on the capacity release amount, the capacity of the cell whose capacity needs to be released is released through a low-power resistor network. If the target sodium-ion battery pack does not meet the capacity balance condition, a single cell screening threshold is determined, and based on the single cell screening threshold, a single cell to be replaced is selected from each remaining single cell, and the single cell to be replaced is replaced.

[0012] According to a second aspect of the present invention, a sodium-ion battery pack equalization device based on single-cell capacity correction is provided, comprising: The acquisition unit is used to respond to the capacity balancing signal of the target sodium-ion battery pack, determine the charging reference cell and the discharging reference cell in each individual cell of the target sodium-ion battery pack, and acquire the voltage, current, temperature and charge / discharge cycle number of each individual cell in the target sodium-ion battery pack in real time. The first determining unit is used to determine the actual usable capacity of the corresponding single cell based on the voltage, current, temperature, and charge / discharge cycle number. The actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining single cells. The remaining single cells are the single cells in the target sodium-ion battery pack after removing the charging reference cell and the discharging reference cell. The second determining unit is used to determine the remaining charging time difference between each remaining single cell and the charging reference cell, and to determine the remaining rechargeable capacity of the corresponding remaining single cell based on the remaining charging time difference, the actual available capacity of each remaining single cell, and the actual available capacity of the charging reference cell. The third determining unit is used to determine the remaining discharge time difference between each remaining single cell and the discharge reference cell, and to determine the remaining dischargeable capacity of the corresponding remaining single cell based on the remaining discharge time difference, the actual usable capacity of each remaining single cell, and the actual usable capacity of the discharge reference cell. The equalization unit is used to equalize the capacity of each individual cell in the target sodium-ion battery pack based on the remaining rechargeable capacity and remaining dischargeable capacity of each remaining individual cell.

[0013] According to a third aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the above-described sodium-ion battery pack balancing method based on single-cell capacity correction.

[0014] According to a fourth aspect of the present invention, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-described sodium-ion battery pack balancing method based on single-cell capacity correction.

[0015] According to the present invention, a sodium-ion battery pack balancing method and apparatus based on cell capacity correction is provided. Compared with the current method of balancing sodium-ion battery packs by dissipating the energy of excess cells in the pack through resistors, the present invention, in response to the capacity balancing signal of the target sodium-ion battery pack, determines the charging reference cell and the discharging reference cell among the individual cells of the target sodium-ion battery pack, and collects the voltage, current, temperature, and charge / discharge cycle count of each individual cell in the target sodium-ion battery pack in real time; and determines the actual usable capacity of the corresponding individual cell based on the voltage, current, temperature, and charge / discharge cycle count. The actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining individual cells, wherein the remaining individual cells are the target sodium-ion battery pack. The sodium-ion battery pack is divided into several parts. First, the remaining cells are separated from the charging reference cell and the discharging reference cell. Then, the remaining charging time difference between each remaining cell and the charging reference cell is determined. Based on the remaining charging time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the charging reference cell, the remaining rechargeable capacity of the corresponding remaining cell is determined. Next, the remaining discharging time difference between each remaining cell and the discharging reference cell is determined. Based on the remaining discharging time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the discharging reference cell, the remaining discharging capacity of the corresponding remaining cell is determined. Finally, based on the remaining rechargeable capacity and remaining discharging capacity of each remaining cell, the capacity of each cell in the target sodium-ion battery pack is balanced. Therefore, by determining the charging / discharging reference cell and establishing a dynamic reference standard, the balancing strategy is made more closely aligned with actual operating conditions, avoiding the use of fixed thresholds or average values ​​as balancing targets. By collecting voltage, current, temperature, and charge / discharge cycle counts in real time, the actual usable capacity of a single cell can be accurately determined, avoiding the limitations of traditional voltage balancing and thus improving the accuracy of capacity balancing in sodium-ion battery packs. Calculating the remaining charge / discharge capacity using the remaining charge / discharge time difference enables precise calculation of energy transfer, avoiding over-balancing or under-balancing. By balancing the capacity of individual cells within the target sodium-ion battery pack, without relying on external resistors, energy utilization can be improved, battery overheating can be avoided, and the lifespan of the battery pack can be extended. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1This invention provides a flowchart of a sodium-ion battery pack equalization method based on single-cell capacity correction according to an embodiment of the present invention. Figure 2 This invention provides a flowchart of another sodium-ion battery pack balancing method based on single-cell capacity correction. Figure 3 This diagram illustrates a structural schematic of a sodium-ion battery pack equalization device based on single-cell capacity correction provided in an embodiment of the present invention. Figure 4 This invention provides a schematic diagram of another sodium-ion battery pack equalization device based on single-cell capacity correction, according to an embodiment of the present invention. Figure 5 A schematic diagram of the physical structure of a computer device provided in an embodiment of the present invention is shown. Detailed Implementation

[0017] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the present application can be combined with each other.

[0018] Currently, in the capacity balancing process of sodium-ion battery packs, the energy of excess capacity cells in the sodium-ion battery pack is usually consumed by resistors. This method has low energy utilization and also poses a risk of high battery temperature, thereby reducing the lifespan of the sodium-ion battery pack.

[0019] To address the aforementioned problems, embodiments of the present invention provide a sodium-ion battery pack balancing method based on single-cell capacity correction, such as... Figure 1 As shown, the method includes: 101. In response to the capacity balancing signal of the target sodium-ion battery pack, determine the charging reference cell and the discharging reference cell in each individual cell of the target sodium-ion battery pack, and collect the voltage, current, temperature and charge / discharge cycle number of each individual cell in the target sodium-ion battery pack in real time.

[0020] In this embodiment of the invention, the target sodium-ion battery pack consists of multiple cells. To perform capacity balancing on the target sodium-ion battery pack, constant current charging and discharging are first performed. During the charging and discharging process, the dynamic voltage and corresponding time of each individual cell are collected. Based on the dynamic voltage, a charging reference cell and a discharging reference cell are determined. These two reference cells are used as dynamic reference standards for the charging and discharging processes, respectively, to quantify the capacity differences between cells and guide the balancing operation. Simultaneously, voltage, current, and temperature data of each cell within the sodium-ion battery pack are collected in real time using voltage sensors, current sensors, and temperature sensors. The collection frequency can also be set to collect this data. The number of charge-discharge cycles of each cell is also recorded. By determining the charging / discharging reference cells and establishing dynamic reference standards, this embodiment of the invention avoids using fixed thresholds or average values ​​as balancing targets, making the balancing strategy more closely aligned with actual operating conditions.

[0021] 102. Based on voltage, current, temperature, and charge / discharge cycle count, determine the actual usable capacity of the corresponding single cell. The actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining single cells. The remaining single cells are the single cells in the target sodium-ion battery pack after removing the charging reference cell and the discharging reference cell.

[0022] In this embodiment of the invention, a capacity prediction model is pre-constructed. For each individual cell, its corresponding voltage, current, temperature, and charge-discharge cycle count are input into the capacity prediction model. The actual usable capacity of each individual cell is then predicted by the capacity prediction model. This embodiment of the invention, by using real-time collected voltage, current, temperature, and charge-discharge cycle count, can accurately determine the actual usable capacity of an individual cell, avoiding the limitations of traditional voltage balancing, thereby improving the accuracy of capacity balancing in sodium-ion battery packs.

[0023] 103. Determine the remaining charging time difference between each remaining single cell and the charging reference cell, and based on the remaining charging time difference, the actual available capacity of each remaining single cell, and the actual available capacity of the charging reference cell, determine the remaining rechargeable capacity of the corresponding remaining single cell.

[0024] In this embodiment of the invention, the difference between the remaining time required for each remaining single cell to charge from the current voltage to the cutoff voltage and the remaining charging time of the charging reference cell is predetermined. This difference is used as the remaining charging time difference. Then, based on the remaining charging time difference, the actual usable capacity of each remaining single cell, and the actual usable capacity of the charging reference cell, the remaining rechargeable capacity of the corresponding remaining single cell is determined. The remaining charging time difference directly reflects the capacity and internal resistance differences between cells. Cells with lower capacity or higher internal resistance charge slower under the same current, resulting in a longer remaining charging time; conversely, cells with higher capacity or lower internal resistance charge faster, resulting in a shorter remaining charging time. Therefore, balancing the battery pack using the remaining charging time difference can improve the balancing accuracy of the battery pack.

[0025] 104. Determine the remaining discharge time difference between each remaining cell and the discharge reference cell, and based on the remaining discharge time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the discharge reference cell, determine the remaining dischargeable capacity of the corresponding remaining cell.

[0026] In this embodiment of the invention, the difference between the remaining time for each remaining individual cell to discharge from its current state to the minimum protection voltage and the remaining time for the discharge reference cell is predetermined, and this difference is used as the remaining discharge time difference. Then, based on the remaining discharge time difference, the actual usable capacity of each remaining individual cell, and the actual usable capacity of the discharge reference cell, the remaining dischargeable capacity of the corresponding remaining individual cell is determined. By analyzing the remaining discharge time difference, the problem of cells that discharge prematurely reaching the minimum protection voltage while other cells are not fully discharged can be avoided, thereby improving the overall capacity utilization rate.

[0027] 105. Based on the remaining rechargeable capacity and remaining dischargeable capacity of each remaining single cell, the capacity of each single cell in the target sodium-ion battery pack is balanced.

[0028] Among them, remaining rechargeable capacity and remaining dischargeable capacity are key parameters for quantifying the current state of a battery cell. Remaining rechargeable capacity refers to the amount of charge that the battery cell can absorb when charging from its current state to a fully charged state; remaining dischargeable capacity refers to the amount of charge that the battery cell can release when discharging from its current state to the minimum protection voltage.

[0029] In this embodiment of the invention, charge redistribution is achieved through energy transfer between battery cells based on the remaining rechargeable capacity and remaining dischargeable capacity, thereby improving energy utilization. Specifically, a threshold for the remaining rechargeable capacity or remaining dischargeable capacity can be set, and equalization is triggered when a battery cell exceeds the threshold. For example, if the remaining dischargeable capacity of cell A is 10% higher than a reference value, some of its energy is transferred to cell B with a lower capacity through active equalization. This avoids energy waste caused by relying on external components for energy transfer. Therefore, this embodiment of the invention improves energy utilization and prevents battery overheating by equalizing the capacity of each individual cell in the target sodium-ion battery pack, thus extending the battery pack's lifespan.

[0030] In another embodiment of the present invention, during the equalization process, for example, cell voltage and current data are collected every 0.5 seconds. If the cell voltage is detected to be higher than 3.8V (overcharge threshold) or lower than 1.5V (over-discharge threshold), the output power of the DC / DC converter is immediately adjusted until the remaining rechargeable capacity and remaining discharge capacity of all cells meet the requirements, that is, when the capacity difference of all cells drops to a preset threshold, such as below 2Ah, the equalization is stopped. By accurately judging the cell status, targeted charging and discharging operations are performed only on cells with insufficient capacity, avoiding energy waste by using external components such as resistors, and eliminating the need for complex equalization hardware. At the same time, the accurate judgment of the equalization operation reduces the number of invalid equalizations, reduces equipment loss and energy consumption, and extends the overall life of the battery pack.

[0031] For example, consider a sodium-ion battery pack composed of 16 sodium-ion cells connected in series: Target capacity =100Ah, charging cutoff voltage is 3.85V, discharging cutoff voltage is 2.0V, constant current charging current =10A, constant current discharge current =10A, preset voltage acquisition interval is 10s. Constant current charging is started, and the voltage sensor acquires the voltage of each cell every 10s. Charging stops when the 8th cell reaches 3.85V, and the 8th cell is marked as the charging reference cell. =105Ah), record the charging cutoff voltage and time of each cell. After resting for 30 minutes, start constant current discharge, and collect the voltage every 10 seconds. Stop the discharge when the 12th cell reaches 2.0V, and mark the 12th cell as the discharge reference cell ( =102Ah), record the discharge cutoff voltage and time of each cell. Using the voltage-time data of cell 8 as a reference, for cell 3 ( The remaining charging time difference Δ is obtained by interpolating the charging cutoff voltage (3.2V) of 98Ah. =120s, calculate the remaining rechargeable capacity according to the formula. : =10A×120s×(98 / 105)=1120C≈0.31Ah. Using the voltage-time data of the 12th cell as a reference, the discharge cutoff voltage (1.1V) of the 3rd cell is interpolated to obtain the remaining discharge time difference Δ. =90s, calculate the remaining discharge capacity according to the formula. : =10A×90s×(98 / 102)=864.7C≈0.24Ah. The current discharge capacity of the battery pack is measured. =92Ah, calculate =12Ah, =10Ah, current usable capacity of the battery pack =10Ah≥8Ah (ΔQ=100-92=8Ah), no cell replacement required, enter the equalization execution phase; remaining rechargeable flux of the third cell. =0.31Ah≤8Ah, calculate the capacity transfer amount. =8 - 0.31 = 7.69 Ah; Remaining discharge capacity =0.24Ah≤8Ah, and simultaneously calculate the capacity release. =8-0.24=7.76Ah. At this point, the bidirectional DC / DC converter is controlled to charge the third cell for 7.76Ah and then discharge it for 7.69Ah until its remaining chargeable and dischargeable capacity meets the 8Ah requirement. Similarly, the balancing operation of other cells is completed. After balancing, the actual discharge capacity of the battery pack is increased to 99.5Ah.

[0032] This invention provides a sodium-ion battery pack balancing method based on cell capacity correction. Compared to current methods that typically consume excess capacity cells in sodium-ion battery packs through resistors during capacity balancing, this invention, in response to the capacity balancing signal of the target sodium-ion battery pack, determines a charging reference cell and a discharging reference cell among the individual cells of the target sodium-ion battery pack, and collects the voltage, current, temperature, and charge / discharge cycle count of each individual cell in the target sodium-ion battery pack in real time. Based on the voltage, current, temperature, and charge / discharge cycle count, the actual usable capacity of the corresponding individual cell is determined. The actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining individual cells, where the remaining individual cells are the target sodium-ion battery pack cells. The process involves removing the charging reference cell and the discharging reference cell from the sub-battery pack; simultaneously, determining the remaining charging time difference between each remaining cell and the charging reference cell, and determining the remaining rechargeable capacity of the corresponding remaining cell based on the remaining charging time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the charging reference cell; then determining the remaining discharging time difference between each remaining cell and the discharging reference cell, and determining the remaining discharging capacity of the corresponding remaining cell based on the remaining discharging time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the discharging reference cell; finally, based on the remaining rechargeable capacity and remaining discharging capacity of each remaining cell, the capacity of each cell in the target sodium-ion battery pack is balanced. Therefore, by determining the charging / discharging reference cell and establishing a dynamic reference standard, the balancing strategy is made more closely aligned with actual operating conditions, avoiding the use of fixed thresholds or average values ​​as balancing targets. By collecting voltage, current, temperature, and charge / discharge cycle counts in real time, the actual usable capacity of a single cell can be accurately determined, avoiding the limitations of traditional voltage balancing and thus improving the accuracy of capacity balancing in sodium-ion battery packs. Calculating the remaining charge / discharge capacity using the remaining charge / discharge time difference enables precise calculation of energy transfer, avoiding over-balancing or under-balancing. By balancing the capacity of individual cells within the target sodium-ion battery pack, without relying on external resistors, energy utilization can be improved, battery overheating can be avoided, and the lifespan of the battery pack can be extended.

[0033] Furthermore, to better illustrate the above-described balancing process for sodium-ion battery packs based on individual cell capacity correction, as a refinement and extension of the above embodiments, this invention provides another balancing method for sodium-ion battery packs based on individual cell capacity correction, such as... Figure 2 As shown, the method includes: 201. In response to the capacity balancing signal of the target sodium-ion battery pack, determine the charging reference cell and the discharging reference cell in each individual cell of the target sodium-ion battery pack, and collect the voltage, current, temperature and charge / discharge cycle number of each individual cell in the target sodium-ion battery pack in real time.

[0034] In this embodiment of the invention, in order to achieve capacity balancing of the battery pack, it is first necessary to determine the charging reference cell and the discharging reference cell. Based on this, step 201 specifically includes: performing constant current charging on the target sodium-ion battery pack, collecting the dynamic charging voltage of each individual cell at a preset charging time interval, and using the individual cell whose dynamic charging voltage reaches the preset charging cutoff voltage as the charging reference cell; performing constant current discharging on the target sodium-ion battery pack, collecting the dynamic discharging voltage of each individual cell at a preset discharging time interval, and using the individual cell whose dynamic discharging voltage reaches the preset discharging cutoff voltage as the discharging reference cell.

[0035] The preset charging and discharging time intervals, as well as the charging and discharging cutoff voltages, are set according to actual needs. For example, the charging cutoff voltage can be the highest voltage limit allowed for the sodium-ion battery pack during charging, and the discharging cutoff voltage can be the lowest voltage limit allowed for the sodium-ion battery pack during discharging. Specifically, the sodium-ion battery pack is charged at a constant current, and the dynamic voltage of each cell is collected at preset charging time intervals until a certain cell reaches the charging cutoff voltage first. This cell that reaches the charging cutoff voltage first is designated as the charging reference cell, and the charging cutoff voltage and corresponding charging time of all cells are recorded. Simultaneously, the sodium-ion battery pack is discharged at a constant current, and the dynamic voltage of each cell is collected at the same preset time intervals until any cell reaches the discharging cutoff voltage. This cell that reaches the discharge cutoff voltage first is designated as the discharging reference cell, and the discharging cutoff voltage and corresponding discharging time of all cells are recorded. For example, a preset charging cutoff voltage is set... (3.85±0.05V), preset discharge cutoff voltage (2.0±0.05V), charging / discharging current I (0.5-1C), voltage sampling frequency f≥10Hz; constant current charging is performed when the voltage of the first cell reaches... At that time, it was marked as a charging reference cell. (capacity Record charging time Synchronously perform constant current discharge and mark the discharge reference cell. (capacity Record the discharge duration. Then, sensors and other devices are used to collect parameters such as voltage, current, temperature, and charge / discharge cycle count of each individual cell in the target sodium-ion battery pack in real time.

[0036] 202. Determine multiple sodium-ion battery cell samples, set multiple sample temperature points in a temperature chamber, and based on each sample temperature point, perform cyclic charge-discharge operations on the sodium-ion battery cell samples in the temperature chamber at multiple charge-discharge rates until the cell capacity of each sodium-ion battery cell sample decays to meet the requirements. Record the actual cell capacity of each sodium-ion battery cell sample under different sample temperatures, different sample currents, and different sample voltages in each cycle of charge-discharge operation.

[0037] 203. Based on the actual cell capacity of each sodium ion cell sample under different temperatures, currents, and voltages during each charge-discharge cycle, a preset capacity prediction model is constructed.

[0038] Specifically, for example, 30 sodium-ion battery cell samples of the same model as the battery pack were selected. Five temperature points were set in a temperature chamber: -20℃, 0℃, 25℃, 45℃, and 60℃. Cycle life tests were conducted at charge / discharge rates of 0.1C, 0.5C, 1C, and 2C, respectively, until the cell capacity decayed to 80% of its initial capacity. The actual cell capacity at different temperatures, rates (currents), and voltages for each cycle (0-2000 cycles) was recorded. A neural network algorithm was used to fit the data, resulting in a preset capacity prediction model as shown below:

[0039] Where Cact is the actual available capacity, U is the voltage, I is the current, T is the temperature, N is the number of cycles, and f() is the capacity prediction function.

[0040] 204. Input the voltage, current, temperature, and charge / discharge cycle count of each individual cell into the preset capacity prediction model to predict the actual usable capacity of each individual cell.

[0041] The actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining individual cells. The remaining individual cells are the individual cells in the target sodium-ion battery pack after removing the charging reference cell and the discharging reference cell.

[0042] Specifically, for each individual battery cell, its corresponding voltage, current, temperature, and charge / discharge cycle count are input into a preset capacity prediction model. This model directly outputs the actual usable capacity of each individual battery cell. This embodiment of the invention uses a model to predict the actual usable capacity of the battery cell, thereby improving the prediction efficiency and accuracy.

[0043] In another embodiment of the present invention, in order to improve the accuracy of determining the actual usable capacity, the method further includes: acquiring cell health status data for each individual cell. Among them, cell health status data The actual factory capacity of each cell is measured by performing a preset number of charge-discharge cycles on a single cell. Based on the actual factory capacity and the cell health status data The current actual capacity of each individual cell i is calculated according to the following formula. :

[0044] Furthermore, for each elevator battery cell, its current actual capacity is determined. If the actual available capacity is different from that predicted by the preset capacity prediction model, then determine the current actual capacity separately. The weighting coefficient corresponding to the actual available capacity, based on the weighting coefficient, will determine the current actual capacity. The corrected actual usable capacity of each individual cell is obtained by weighted summation with the actual usable capacity. This corrected actual usable capacity is then used for capacity balancing of the battery pack. This embodiment of the invention improves the accuracy of battery capacity determination by correcting the actual usable capacity, thereby enhancing the accuracy of battery pack capacity balancing.

[0045] 205. Determine the remaining charging time difference between each remaining single cell and the charging reference cell, and based on the remaining charging time difference, the actual available capacity of each remaining single cell, and the actual available capacity of the charging reference cell, determine the remaining rechargeable capacity of the corresponding remaining single cell.

[0046] In this embodiment of the invention, to determine the remaining rechargeable capacity of a battery cell, it is first necessary to determine the remaining charging time difference between the remaining individual battery cells and the charging reference cell. Based on this, step 205 specifically includes: constructing a pre-plateau charging linear function and a post-plateau charging linear function based on the relationship between the charging time and charging voltage of the charging reference cell before and after the voltage plateau period; determining the starting charging time of the charging reference cell before the voltage plateau period; determining the starting charging voltage of the plateau period using the pre-plateau charging linear function based on the starting charging time; determining the ending charging time of the charging reference cell after the voltage plateau period; determining the ending charging voltage of the plateau period using the post-plateau charging linear function based on the ending charging time; determining the charging cutoff voltage of each remaining individual battery cell; and determining the charging time for the charging reference cell to reach the preset charging cutoff voltage during constant current charging. Based on the start charging time, the end charging time, the start charging voltage of the plateau period, and the end charging voltage of the plateau period, the charging time corresponding to the voltage at the charging cutoff point is determined. The charging time and the charging time The difference between them is taken as the remaining charging time difference. .

[0047] Specifically, the charging time and charging voltage of the reference cell are collected before and after the voltage plateau period. The functional relationship between charging time and charging voltage is determined, and based on this relationship, the linear function for charging before the plateau period is constructed as: Uq-ch(t) = k1t + b1, and the linear function for charging after the plateau period is: Uh-ch(t) = k2t + b2. Here, Uq-ch(t) is the charging voltage before the plateau period at time t, and k1 and b1 are constant coefficients; Uh-ch(t) is the charging voltage after the plateau period at time t, and k2 and b2 are constant coefficients. Further, the charging time of the remaining single cell i when it reaches the charging cutoff voltage is calculated according to the following formula. :

[0048] in, For the initial charging time, To end the charging time, The voltage at which the charging of the remaining single cell i is cut off. The initial charging voltage during the plateau period, This is the charging voltage at the end of the plateau period. The final charging time will be... and the charging time The difference between them is taken as the remaining charging time difference. The aforementioned remaining charging time difference can also be obtained through linear interpolation of the charging linear function before the plateau period and the charging linear function after the plateau period.

[0049] Furthermore, it is necessary to determine the remaining rechargeable capacity of each remaining individual cell based on the remaining charging time difference. Therefore, step 205 specifically includes: determining the constant current charging current of the target sodium-ion battery pack. and charging efficiency Based on the remaining charging time difference Each remaining single cell Actual available capacity The actual usable capacity of the charging reference cell Determine the corresponding remaining individual battery cells Remaining rechargeable capacity ,in, .

[0050] Specifically, the remaining rechargeable capacity is calculated by introducing a correction factor for the actual usable capacity of the battery cell and the actual usable capacity of the charging reference battery cell, as well as the charging efficiency.

[0051] 206. Determine the remaining discharge time difference between each remaining cell and the discharge reference cell, and based on the remaining discharge time difference, the actual available capacity of each remaining cell, and the actual available capacity of the discharge reference cell, determine the remaining dischargeable capacity of the corresponding remaining cell.

[0052] In this embodiment of the invention, to determine the remaining discharge capacity of a battery cell, it is first necessary to determine the remaining discharge time difference between the remaining individual battery cells and the discharge reference cell. Based on this, step 206 specifically includes: constructing a pre-plateau discharge linear function and a post-plateau discharge linear function based on the relationship between the discharge time and discharge voltage of the discharge reference cell before and after the voltage plateau period; determining the starting discharge time of the discharge reference cell before the voltage plateau period; determining the starting discharge voltage of the plateau period using the pre-plateau discharge linear function based on the starting discharge time; determining the ending discharge time of the discharge reference cell after the voltage plateau period; determining the ending discharge voltage of the plateau period using the post-plateau discharge linear function based on the ending discharge time; determining the discharge cutoff voltage of each remaining individual battery cell; and determining the discharge duration for the discharge reference cell to reach the preset discharge cutoff voltage during constant current discharge. Based on the start discharge time, the end discharge time, the start discharge voltage of the plateau period, and the end discharge voltage of the plateau period, the discharge time corresponding to the discharge cutoff voltage is determined. The discharge duration and the discharge time The difference between them is taken as the remaining discharge time difference. .

[0053] Specifically, the discharge time and discharge voltage of the reference cell are collected during the discharge process before and after the voltage plateau period. The functional relationship between discharge time and discharge voltage is determined, and based on this relationship, the linear function of discharge before the plateau period is constructed as: Uq-dis(t) = k3t + b3, and the linear function of discharge after the plateau period is: Uh-dis(t) = k4t + b4. Where Uq-dis(t) is the discharge voltage before the plateau period at time t, and k3 and b3 are constant coefficients; Uh-dis(t) is the discharge voltage after the plateau period at time t, and k4 and b4 are constant coefficients. Further, the discharge time of the remaining single cell i when it reaches the discharge cutoff voltage is calculated according to the following formula. :

[0054] in, For the initial discharge time, To end the discharge time, The voltage at which the remaining single cell i is discharged off. For the plateau period initial discharge voltage, This is the discharge voltage at the end of the plateau phase. The final discharge duration will be... and discharge time The difference between them is taken as the remaining discharge time difference. The aforementioned remaining discharge time difference can also be obtained through linear interpolation of the discharge linear function before the plateau period and the discharge linear function after the plateau period.

[0055] Furthermore, it is necessary to determine the remaining discharge capacity of each remaining individual cell based on the remaining discharge time difference. Therefore, step 206 specifically includes: determining the constant current discharge current of the target sodium-ion battery pack. and discharge efficiency ; Based on the remaining discharge time difference Each remaining single cell Actual available capacity The actual usable capacity of the discharge reference cell Determine the corresponding remaining individual battery cells Remaining discharge capacity ,in, .

[0056] Specifically, the remaining dischargeable capacity is calculated by introducing a correction factor for the actual usable capacity of the battery cell and the actual usable capacity of the discharge reference battery cell, as well as the discharge efficiency.

[0057] 207. Based on the remaining rechargeable capacity and remaining dischargeable capacity of each remaining single cell, the capacity of each single cell in the target sodium-ion battery pack is balanced.

[0058] In this embodiment of the invention, after determining the remaining rechargeable capacity and remaining dischargeable capacity of each remaining cell, it is necessary to perform capacity balancing processing on each cell based on the remaining rechargeable capacity and remaining dischargeable capacity. Therefore, step 207 specifically includes: determining the sum of the remaining rechargeable capacity of each remaining individual cell, and determining the sum of the remaining dischargeable capacity of each remaining individual cell. The minimum value among the sum of the remaining rechargeable capacity and the sum of the remaining dischargeable capacity is taken as the current available capacity of the target sodium-ion battery pack. Based on the actual factory capacity of the target sodium-ion battery pack, a preset capacity threshold is determined. Based on the currently available capacity and the preset capacity threshold The process involves determining whether the target sodium-ion battery pack meets the capacity balancing condition among individual cells. If the target sodium-ion battery pack meets the capacity balancing condition, the actual factory capacity and current discharge capacity of the target sodium-ion battery pack are determined, and based on the actual factory capacity and current discharge capacity of the target sodium-ion battery pack, the balancing capacity is determined. Based on the balancing capacity and the remaining rechargeable capacity of each remaining individual cell, low-capacity cells and high-capacity cells are identified in each remaining individual cell, and based on the balancing capacity and the remaining rechargeable capacity, the capacity transfer amount is determined. Based on the capacity transfer amount, the high-capacity cells are transferred... The capacity is transferred to the low-capacity individual cells; based on the balanced capacity and the remaining dischargeable capacity of each remaining individual cell, the individual cells whose capacity needs to be released are determined in each remaining individual cell, and the capacity release amount is determined based on the balanced capacity and the remaining dischargeable capacity, and the capacity of the individual cells whose capacity needs to be released is released through a low-power resistor network based on the capacity release amount; if the target sodium-ion battery pack does not meet the capacity balancing condition, a single cell screening threshold is determined, and based on the single cell screening threshold, a single cell to be replaced is selected in each remaining individual cell, and the single cell to be replaced is replaced.

[0059] Specifically, the current available capacity is determined according to the following formula. :

[0060] in, The sum of remaining rechargeable capacity. This is the sum of the remaining dischargeable capacities. Then, a preset capacity threshold is determined. , Where C01 represents the actual factory capacity of the remaining battery cells. This is the capacity factor.

[0061] Furthermore, if the current available capacity Greater than or equal to the preset capacity threshold If the target sodium-ion battery pack meets the capacity balancing condition among individual cells, then capacity balancing processing is required for each cell. First, the balanced capacity is determined. , ,in, This is the actual capacity at the factory. The current discharge capacity. The remaining rechargeable capacity must be greater than or equal to the equalization capacity. The battery cells were determined to be high-capacity single cells, with remaining rechargeable capacity less than the equalization capacity. The cells are identified as low-capacity individual cells. The difference between the balanced capacity and the remaining rechargeable capacity of the low-capacity individual cells is used as the capacity transfer amount. Then, an amount of capacity equal to the capacity transfer amount is transferred from the high-capacity individual cells to the low-capacity individual cells. Further, cells with remaining dischargeable capacity less than the balanced capacity are identified as individual cells requiring capacity release, and the amount of capacity release is determined accordingly. , , The remaining discharge capacity of cell i is then used to release the capacity of the cell whose capacity needs to be released, with the same capacity release amount.

[0062] Furthermore, if the current available capacity Less than the preset capacity threshold If the target sodium-ion battery pack does not meet the capacity balance condition among individual cells, then the cells need to be replaced. First, determine the cell screening threshold. , , The actual capacity of the battery cell at the factory. The selection coefficient is set according to actual needs, such as 0.05. Cells with remaining rechargeable capacity or remaining discharge capacity less than the cell selection threshold are then selected as replacement cells. These replacement cells are then replaced with new cells to ensure the stable operation of the battery pack.

[0063] According to another sodium-ion battery pack equalization method based on cell capacity correction provided by the present invention, compared with the current method of consuming the energy of excess cells in the sodium-ion battery pack through resistors during the capacity equalization process, the present invention determines the charging reference cell and the discharging reference cell in each cell of the target sodium-ion battery pack in response to the capacity equalization signal of the target sodium-ion battery pack, and collects the voltage, current, temperature, and charge-discharge cycle number of each cell in the target sodium-ion battery pack in real time; and determines the actual usable capacity of the corresponding cell based on the voltage, current, temperature, and charge-discharge cycle number, wherein the actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining cells, the remaining cells being the target sodium-ion battery pack. The process involves removing the charging reference cell and the discharging reference cell from the sub-battery pack; simultaneously, determining the remaining charging time difference between each remaining cell and the charging reference cell, and determining the remaining rechargeable capacity of the corresponding remaining cell based on the remaining charging time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the charging reference cell; then determining the remaining discharging time difference between each remaining cell and the discharging reference cell, and determining the remaining discharging capacity of the corresponding remaining cell based on the remaining discharging time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the discharging reference cell; finally, based on the remaining rechargeable capacity and remaining discharging capacity of each remaining cell, the capacity of each cell in the target sodium-ion battery pack is balanced. Therefore, by determining the charging / discharging reference cell and establishing a dynamic reference standard, the balancing strategy is made more closely aligned with actual operating conditions, avoiding the use of fixed thresholds or average values ​​as balancing targets. By collecting voltage, current, temperature, and charge / discharge cycle counts in real time, the actual usable capacity of a single cell can be accurately determined, avoiding the limitations of traditional voltage balancing and thus improving the accuracy of capacity balancing in sodium-ion battery packs. Calculating the remaining charge / discharge capacity using the remaining charge / discharge time difference enables precise calculation of energy transfer, avoiding over-balancing or under-balancing. By balancing the capacity of individual cells within the target sodium-ion battery pack, without relying on external resistors, energy utilization can be improved, battery overheating can be avoided, and the lifespan of the battery pack can be extended.

[0064] Furthermore, as Figure 1 In specific implementation, embodiments of the present invention provide a sodium-ion battery pack balancing device based on single-cell capacity correction, such as... Figure 3 As shown, the device includes: a data acquisition unit 31, a first determination unit 32, a second determination unit 33, a third determination unit 34, and an equalization unit 35.

[0065] The acquisition unit 31 can be used to determine the charging reference cell and the discharging reference cell in each individual cell of the target sodium-ion battery pack in response to the capacity balancing signal of the target sodium-ion battery pack, and to acquire the voltage, current, temperature and charge / discharge cycle number of each individual cell in the target sodium-ion battery pack in real time.

[0066] The first determining unit 32 can be used to determine the actual usable capacity of the corresponding single cell based on the voltage, current, temperature and charge / discharge cycle number. The actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining single cells. The remaining single cells are the single cells in the target sodium-ion battery pack after removing the charging reference cell and the discharging reference cell.

[0067] The second determining unit 33 can be used to determine the remaining charging time difference between each remaining single cell and the charging reference cell, and based on the remaining charging time difference, the actual available capacity of each remaining single cell, and the actual available capacity of the charging reference cell, determine the remaining rechargeable capacity of the corresponding remaining single cell.

[0068] The third determining unit 34 can be used to determine the remaining discharge time difference between each remaining single cell and the discharge reference cell, and based on the remaining discharge time difference, the actual usable capacity of each remaining single cell, and the actual usable capacity of the discharge reference cell, determine the remaining dischargeable capacity of the corresponding remaining single cell.

[0069] The equalization unit 35 can be used to equalize the capacity of each individual cell in the target sodium-ion battery pack based on the remaining rechargeable capacity and remaining dischargeable capacity of each remaining individual cell.

[0070] In specific application scenarios, in order to determine the charging reference cell and the discharging reference cell, the acquisition unit 31 can be used to perform constant current charging on the target sodium-ion battery pack, acquire the dynamic charging voltage of each individual cell at a preset charging time interval, and select the individual cell whose dynamic charging voltage reaches the preset charging cutoff voltage as the charging reference cell; and perform constant current discharging on the target sodium-ion battery pack, acquire the dynamic discharging voltage of each individual cell at a preset discharging time interval, and select the individual cell whose dynamic discharging voltage reaches the preset discharging cutoff voltage as the discharging reference cell.

[0071] In specific application scenarios, in order to determine the actual usable capacity of a single battery cell, such as Figure 4 As shown, the first determining unit 32 includes a discharge operation module 321, a model building module 322, and a prediction module 323.

[0072] The discharge operation module 321 can be used to determine multiple sodium-ion battery cell samples, set multiple sample temperature points in the temperature chamber, and perform cyclic charge and discharge operations on the sodium-ion battery cell samples in the temperature chamber at multiple charge and discharge rates based on each sample temperature point until the cell capacity of each sodium-ion battery cell sample decays to meet the requirements. The module records the actual cell capacity of each sodium-ion battery cell sample under different sample temperatures, different sample currents, and different sample voltages in each cycle of charge and discharge operation.

[0073] The model building module 322 can be used to build a preset capacity prediction model based on the actual capacity of each sodium ion cell sample under different temperatures, currents, and voltages in each cycle of charge and discharge.

[0074] The prediction module 323 can be used to input the voltage, current, temperature and charge / discharge cycle number of each individual cell into the preset capacity prediction model to predict the capacity and obtain the actual usable capacity of each individual cell.

[0075] In specific application scenarios, in order to determine the remaining charging time difference, the second determining unit 33 includes a first function construction module 331 and a first determining module 332.

[0076] The first function construction module 331 can be used to construct a pre-plateau charging linear function and a post-plateau charging linear function based on the relationship between the charging time and the charging voltage during the charging process of the charging reference cell before and after the voltage plateau period.

[0077] The first determining module 332 can be used to determine the starting charging time of the charging reference cell before the voltage plateau period, determine the starting charging voltage of the plateau period using the charging linear function before the plateau period based on the starting charging time, determine the ending charging time of the charging reference cell after the voltage plateau period, and determine the ending charging voltage of the plateau period using the charging linear function after the plateau period based on the ending charging time.

[0078] The first determining module 332 can also be used to determine the charging cutoff voltage of each remaining individual cell, and to determine the charging time for the reference cell to reach the preset charging cutoff voltage during constant current charging. Based on the start charging time, the end charging time, the start charging voltage of the plateau period, and the end charging voltage of the plateau period, the charging time corresponding to the voltage at the charging cutoff point is determined. The charging time and the charging time The difference between them is taken as the remaining charging time difference. .

[0079] In specific application scenarios, in order to determine the remaining discharge time difference, the third determining unit 34 includes a second function construction module 341 and a second determining module 342.

[0080] The second function construction module 341 can be used to construct a pre-plateau discharge linear function and a post-plateau discharge linear function based on the relationship between the discharge time and discharge voltage of the discharge reference cell during the discharge process before and after the voltage plateau period.

[0081] The second determining module 342 can be used to determine the starting discharge time of the discharge reference cell before the voltage plateau period, determine the starting discharge voltage of the plateau period using the discharge linear function before the plateau period based on the starting discharge time, determine the ending discharge time of the discharge reference cell after the voltage plateau period, and determine the ending discharge voltage of the plateau period using the discharge linear function after the plateau period based on the ending discharge time.

[0082] The second determining module 342 can also be used to determine the discharge cutoff voltage of each remaining individual cell, and to determine the discharge duration during which the cell voltage of the discharge reference cell reaches the preset discharge cutoff voltage during constant current discharge. Based on the start discharge time, the end discharge time, the start discharge voltage of the plateau period, and the end discharge voltage of the plateau period, the discharge time corresponding to the discharge cutoff voltage is determined. The discharge duration and the discharge time The difference between them is taken as the remaining discharge time difference. .

[0083] In specific application scenarios, in order to determine the remaining rechargeable capacity, the second determining module 332 can also be used to determine the constant current charging current of the target sodium-ion battery pack. and charging efficiency Based on the remaining charging time difference Each remaining single cell Actual available capacity The actual usable capacity of the charging reference cell Determine the corresponding remaining individual battery cells Remaining rechargeable capacity ,in, .

[0084] In specific application scenarios, in order to determine the remaining discharge capacity, the second determining module 342 can also be used to determine the constant current discharge current of the target sodium-ion battery pack. and discharge efficiency Based on the remaining discharge time difference Each remaining single cell Actual available capacity The actual usable capacity of the discharge reference cell Determine the corresponding remaining individual battery cells Remaining discharge capacity ,in, .

[0085] In specific application scenarios, in order to perform equalization processing on the target sodium-ion battery pack, the equalization unit 35 includes a third determination module 351, a judgment module 352, a capacity transfer module 353, a capacity release module 354, and a replacement module 355.

[0086] The third determining module 351 can be used to determine the sum of the remaining rechargeable capacity of each remaining individual cell and the sum of the remaining dischargeable capacity of each remaining individual cell, and the minimum value among the sum of the remaining rechargeable capacity and the sum of the remaining dischargeable capacity is taken as the current available capacity of the target sodium-ion battery pack. Based on the actual factory capacity of the target sodium-ion battery pack, a preset capacity threshold is determined. .

[0087] The judgment module 352 can be used to determine the current available capacity. and the preset capacity threshold Determine whether the target sodium-ion battery pack meets the capacity balance condition among individual cells.

[0088] The third determining module 351 can also be used to determine the actual factory capacity and current discharge capacity of the target sodium-ion battery pack if the target sodium-ion battery pack meets the capacity balancing condition, and to determine the balancing capacity based on the actual factory capacity and current discharge capacity of the target sodium-ion battery pack.

[0089] The capacity transfer module 353 can be used to determine low-capacity cells and high-capacity cells in each remaining cell based on the balanced capacity and the remaining rechargeable capacity of each remaining cell, and to determine the capacity transfer amount based on the balanced capacity and the remaining rechargeable capacity, and to transfer the capacity in the high-capacity cell to the low-capacity cell based on the capacity transfer amount.

[0090] The capacity release module 354 can be used to determine the individual cells whose capacity needs to be released in each remaining individual cell based on the balanced capacity and the remaining dischargeable capacity of each remaining individual cell, and to determine the capacity release amount based on the balanced capacity and the remaining dischargeable capacity, and to release the capacity of the individual cells whose capacity needs to be released through a low-power resistor network based on the capacity release amount.

[0091] The replacement module 355 can be used to determine a single cell screening threshold if the target sodium-ion battery pack does not meet the capacity balancing condition, and based on the single cell screening threshold, to select a single cell to be replaced from each remaining single cell and replace the single cell to be replaced.

[0092] It should be noted that other corresponding descriptions of the functional modules involved in the sodium-ion battery pack balancing device based on single cell capacity correction provided in this embodiment of the invention can be found in the following references. Figure 1 The corresponding description of the method shown will not be repeated here.

[0093] Based on the above, Figure 1 Accordingly, this embodiment of the invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, performs the following steps: In response to a capacity balancing signal of a target sodium-ion battery pack, determining a charging reference cell and a discharging reference cell among the individual cells of the target sodium-ion battery pack, and real-time collecting the voltage, current, temperature, and charge / discharge cycle count of each individual cell in the target sodium-ion battery pack; based on the voltage, current, temperature, and charge / discharge cycle count, determining the actual usable capacity of the corresponding individual cell, wherein the actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining individual cells, the remaining individual cells being the number of cells in the target sodium-ion battery pack excluding the charging reference cell. The system comprises: a reference cell and a discharge reference cell; determining the remaining charging time difference between each remaining cell and the charging reference cell, and determining the remaining rechargeable capacity of the corresponding remaining cell based on the remaining charging time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the charging reference cell; determining the remaining discharging time difference between each remaining cell and the discharge reference cell, and determining the remaining discharging capacity of the corresponding remaining cell based on the remaining discharging time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the discharge reference cell; and performing capacity equalization processing on the cells in the target sodium-ion battery pack based on the remaining rechargeable capacity and remaining discharging capacity of each remaining cell.

[0094] Based on the above, Figure 1 The method shown and asFigure 3 The embodiment of the device shown in the invention also provides a physical structure diagram of a computer device, such as... Figure 5 As shown, the computer device includes: a processor 41, a memory 42, and a computer program stored in the memory 42 and executable on the processor. Both the memory 42 and the processor 41 are mounted on a bus 43. When the processor 41 executes the program, it performs the following steps: In response to a capacity balancing signal of a target sodium-ion battery pack, it determines a charging reference cell and a discharging reference cell among the individual cells of the target sodium-ion battery pack, and collects in real-time the voltage, current, temperature, and charge / discharge cycle count of each individual cell in the target sodium-ion battery pack; Based on the voltage, current, temperature, and charge / discharge cycle count, it determines the actual usable capacity of the corresponding individual cell, wherein the actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining individual cells. The cell is a single cell in the target sodium-ion battery pack after removing the charging reference cell and the discharging reference cell. The remaining charging time difference between each remaining cell and the charging reference cell is determined, and based on the remaining charging time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the charging reference cell, the remaining rechargeable capacity of the corresponding remaining cell is determined. The remaining discharging time difference between each remaining cell and the discharging reference cell is determined, and based on the remaining discharging time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the discharging reference cell, the remaining dischargeable capacity of the corresponding remaining cell is determined. Based on the remaining rechargeable capacity and remaining dischargeable capacity of each remaining cell, the capacity of each cell in the target sodium-ion battery pack is balanced.

[0095] Through the technical solution of this invention, in response to the capacity balancing signal of the target sodium-ion battery pack, this invention determines the charging reference cell and the discharging reference cell in each individual cell of the target sodium-ion battery pack, and collects the voltage, current, temperature, and charge / discharge cycle count of each individual cell in the target sodium-ion battery pack in real time; and determines the actual usable capacity of the corresponding individual cell based on the voltage, current, temperature, and charge / discharge cycle count, wherein the actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining individual cells, the remaining individual cells being the individual cells in the target sodium-ion battery pack after removing the charging reference cell and the discharging reference cell; simultaneously The remaining charging time difference between each remaining cell and the charging reference cell is determined, and the remaining rechargeable capacity of the corresponding remaining cell is determined based on the remaining charging time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the charging reference cell. Then, the remaining discharge time difference between each remaining cell and the discharge reference cell is determined, and the remaining dischargeable capacity of the corresponding remaining cell is determined based on the remaining discharge time difference, the actual usable capacity of each remaining cell, and the actual usable capacity of the discharge reference cell. Finally, based on the remaining rechargeable capacity and remaining dischargeable capacity of each remaining cell, the capacity of each cell in the target sodium-ion battery pack is balanced. Therefore, by determining the charging / discharging reference cell and establishing a dynamic reference standard, the balancing strategy is made more closely aligned with actual operating conditions, avoiding the use of fixed thresholds or average values ​​as balancing targets. By collecting voltage, current, temperature, and charge / discharge cycle counts in real time, the actual usable capacity of a single cell can be accurately determined, avoiding the limitations of traditional voltage balancing and thus improving the accuracy of capacity balancing in sodium-ion battery packs. Calculating the remaining charge / discharge capacity using the remaining charge / discharge time difference enables precise calculation of energy transfer, avoiding over-balancing or under-balancing. By balancing the capacity of individual cells within the target sodium-ion battery pack, without relying on external resistors, energy utilization can be improved, battery overheating can be avoided, and the lifespan of the battery pack can be extended.

[0096] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those presented herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0097] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for balancing sodium-ion battery packs based on single-cell capacity correction, characterized in that, include: In response to the capacity balancing signal of the target sodium-ion battery pack, a charging reference cell and a discharging reference cell are determined in each individual cell of the target sodium-ion battery pack, and the voltage, current, temperature and charge / discharge cycle number of each individual cell in the target sodium-ion battery pack are collected in real time. Based on the voltage, current, temperature, and charge / discharge cycle number, the actual usable capacity of the corresponding single cell is determined. The actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining single cells. The remaining single cells are the single cells in the target sodium-ion battery pack after removing the charging reference cell and the discharging reference cell. Determine the remaining charging time difference between each remaining single cell and the charging reference cell, and based on the remaining charging time difference, the actual available capacity of each remaining single cell, and the actual available capacity of the charging reference cell, determine the remaining rechargeable capacity of the corresponding remaining single cell. Determine the remaining discharge time difference between each remaining single cell and the discharge reference cell, and based on the remaining discharge time difference, the actual usable capacity of each remaining single cell, and the actual usable capacity of the discharge reference cell, determine the remaining dischargeable capacity of the corresponding remaining single cell. Based on the remaining rechargeable and dischargeable capacity of each remaining individual cell, the capacity of each individual cell in the target sodium-ion battery pack is balanced.

2. The method according to claim 1, characterized in that, Determining the charging reference cell and the discharging reference cell among the individual cells of the target sodium-ion battery pack includes: The target sodium-ion battery pack is charged with constant current. The dynamic charging voltage of each individual cell is collected at a preset charging time interval. The individual cell whose dynamic charging voltage reaches the preset charging cutoff voltage is selected as the charging reference cell. The target sodium-ion battery pack is subjected to constant current discharge. The dynamic discharge voltage of each individual cell is collected at a preset discharge time interval. The individual cell whose dynamic discharge voltage reaches the preset discharge cutoff voltage is selected as the discharge reference cell.

3. The method according to claim 1, characterized in that, The determination of the actual usable capacity of a single battery cell based on the voltage, current, temperature, and charge / discharge cycle count includes: Multiple sodium-ion battery cell samples were identified, and multiple sample temperature points were set in a temperature chamber. Based on each sample temperature point, the sodium-ion battery cell samples were subjected to cyclic charge-discharge operations at various charge-discharge rates in the temperature chamber until the cell capacity of each sodium-ion battery cell sample decayed to meet the requirements. The actual cell capacity of each sodium-ion battery cell sample under different sample temperatures, different sample currents, and different sample voltages in each cycle of charge-discharge operation was recorded. Based on the actual capacity of each sodium ion cell sample under different temperatures, currents, and voltages during each charge-discharge cycle, a pre-defined capacity prediction model is constructed. The voltage, current, temperature, and charge / discharge cycle count of each individual cell are input into the preset capacity prediction model to predict the actual usable capacity of each individual cell.

4. The method according to claim 1, characterized in that, Determining the remaining charging time difference between each remaining individual cell and the charging reference cell includes: Based on the relationship between charging time and charging voltage during the charging process of the reference cell before and after the voltage plateau period, a linear function for charging before the voltage plateau period and a linear function for charging after the voltage plateau period are constructed accordingly. The starting charging time of the charging reference cell before the voltage plateau period is determined. Based on the starting charging time, the starting charging voltage of the plateau period is determined using the charging linear function before the plateau period. The ending charging time of the charging reference cell after the voltage plateau period is determined. Based on the ending charging time, the ending charging voltage of the plateau period is determined using the charging linear function after the plateau period. Determine the charging cutoff voltage for each remaining individual battery cell, and determine the charging time for the reference battery cell to reach the preset charging cutoff voltage during constant current charging. Based on the start charging time, the end charging time, the start charging voltage of the plateau period, and the end charging voltage of the plateau period, the charging time corresponding to the voltage at the charging cutoff point is determined. The charging time and the charging time The difference between them is taken as the remaining charging time difference. ; Determining the remaining discharge time difference between each remaining individual cell and the discharge reference cell includes: Based on the relationship between the discharge time and discharge voltage of the discharge reference cell before and after the voltage plateau period, a linear function for discharge before the voltage plateau period and a linear function for discharge after the voltage plateau period are constructed accordingly. The starting discharge time of the discharge reference cell before the voltage plateau period is determined. Based on the starting discharge time, the starting discharge voltage of the plateau period is determined using the discharge linear function before the plateau period. The ending discharge time of the discharge reference cell after the voltage plateau period is determined. Based on the ending discharge time, the ending discharge voltage of the plateau period is determined using the discharge linear function after the plateau period. Determine the discharge cutoff voltage for each remaining individual cell, and determine the discharge duration for the reference cell to reach the preset discharge cutoff voltage during constant current discharge. Based on the start discharge time, the end discharge time, the start discharge voltage of the plateau period, and the end discharge voltage of the plateau period, the discharge time corresponding to the discharge cutoff voltage is determined. The discharge duration and the discharge time The difference between them is taken as the remaining discharge time difference. .

5. The method according to claim 1, characterized in that, The process of determining the remaining rechargeable capacity of a corresponding remaining individual cell based on the remaining charging time difference, the actual usable capacity of each remaining individual cell, and the actual usable capacity of the charging reference cell includes: Determine the constant current charging current of the target sodium-ion battery pack. and charging efficiency ; Based on the remaining charging time difference Each remaining single cell Actual available capacity The actual usable capacity of the charging reference cell Determine the corresponding remaining individual battery cells Remaining rechargeable capacity ,in, .

6. The method according to claim 1, characterized in that, The determination of the remaining discharge capacity of the corresponding remaining individual cell based on the remaining discharge time difference, the actual usable capacity of each remaining individual cell, and the actual usable capacity of the discharge reference cell includes: Determine the constant current discharge current of the target sodium-ion battery pack. and discharge efficiency ; Based on the remaining discharge time difference Each remaining single cell Actual available capacity The actual usable capacity of the discharge reference cell Determine the corresponding remaining individual battery cells Remaining discharge capacity ,in, .

7. The method according to claim 1, characterized in that, The process of balancing the capacity of individual cells in the target sodium-ion battery pack based on the remaining rechargeable and dischargeable capacity of each remaining cell includes: The sum of the remaining rechargeable capacity of each remaining individual cell and the sum of the remaining dischargeable capacity of each remaining individual cell are determined. The minimum value between the sum of the remaining rechargeable capacity and the sum of the remaining dischargeable capacity is taken as the current available capacity of the target sodium-ion battery pack. Based on the actual factory capacity of the target sodium-ion battery pack, a preset capacity threshold is determined. ; Based on the current available capacity and the preset capacity threshold Determine whether the target sodium-ion battery pack meets the capacity balance condition between individual cells; If the target sodium-ion battery pack meets the capacity balancing condition, then the actual factory capacity and current discharge capacity of the target sodium-ion battery pack are determined, and the balancing capacity is determined based on the actual factory capacity and current discharge capacity of the target sodium-ion battery pack. Based on the balanced capacity and the remaining rechargeable capacity of each remaining cell, low-capacity cells and high-capacity cells are identified in each remaining cell. Based on the balanced capacity and the remaining rechargeable capacity, a capacity transfer amount is determined. Based on the capacity transfer amount, the capacity in the high-capacity cell is transferred to the low-capacity cell. Based on the balanced capacity and the remaining dischargeable capacity of each remaining cell, the cell whose capacity needs to be released is determined in each remaining cell. Based on the balanced capacity and the remaining dischargeable capacity, the capacity release amount is determined. Based on the capacity release amount, the capacity of the cell whose capacity needs to be released is released through a low-power resistor network. If the target sodium-ion battery pack does not meet the capacity balance condition, a single cell screening threshold is determined, and based on the single cell screening threshold, a single cell to be replaced is selected from each remaining single cell, and the single cell to be replaced is replaced.

8. A sodium-ion battery pack balancing device based on single-cell capacity correction, characterized in that, include: The acquisition unit is used to respond to the capacity balancing signal of the target sodium-ion battery pack, determine the charging reference cell and the discharging reference cell in each individual cell of the target sodium-ion battery pack, and acquire the voltage, current, temperature and charge / discharge cycle number of each individual cell in the target sodium-ion battery pack in real time. The first determining unit is used to determine the actual usable capacity of the corresponding single cell based on the voltage, current, temperature, and charge / discharge cycle number. The actual usable capacity includes the actual usable capacity of the charging reference cell, the actual usable capacity of the discharging reference cell, and the actual usable capacity of the remaining single cells. The remaining single cells are the single cells in the target sodium-ion battery pack after removing the charging reference cell and the discharging reference cell. The second determining unit is used to determine the remaining charging time difference between each remaining single cell and the charging reference cell, and to determine the remaining rechargeable capacity of the corresponding remaining single cell based on the remaining charging time difference, the actual available capacity of each remaining single cell, and the actual available capacity of the charging reference cell. The third determining unit is used to determine the remaining discharge time difference between each remaining single cell and the discharge reference cell, and to determine the remaining dischargeable capacity of the corresponding remaining single cell based on the remaining discharge time difference, the actual usable capacity of each remaining single cell, and the actual usable capacity of the discharge reference cell. The equalization unit is used to equalize the capacity of each individual cell in the target sodium-ion battery pack based on the remaining rechargeable capacity and remaining dischargeable capacity of each remaining individual cell.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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