SOC calibration method, electronic equipment, storage medium and vehicle

Abstract

The invention discloses an SOC calibration method, electronic equipment, a storage medium and a vehicle. The SOC calibration method comprises the steps that state parameter information of a charging and discharging loop where a battery unit is located is acquired; according to the state parameter information, a target working condition met by the battery unit is determined from at least two preset working conditions, and each preset working condition corresponds to a preset calibration strategy; and determining an SOC calibration value according to a target calibration strategy corresponding to the target working condition. According to the calibration method, the corresponding SOC calibration strategies can be provided for different working conditions based on the at least two preset working conditions, the calibration strategies are diversified, the accuracy of SOC calibration is improved, and the probability of SOC value jump is reduced.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and in particular to a SOC (State of Charge) calibration method, as well as electronic devices, non-volatile readable storage media, and vehicles. Background Technology

[0002] In related technologies, the existing SOC calibration strategy for battery cells is relatively simple, which leads to poor SOC calibration effect under some battery discharge conditions, low accuracy of battery cell SOC value, and long-term inaccurate SOC value calibration, resulting in excessive cumulative error or even SOC value jump. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of this invention is to propose a SOC calibration method that, based on at least two preset operating conditions, can provide corresponding SOC calibration strategies for different operating conditions. This variety of calibration strategies improves the accuracy of SOC calibration and reduces the probability of SOC value jumps.

[0004] The second objective of this invention is to provide an electronic device.

[0005] The third objective of this invention is to provide a non-volatile readable storage medium.

[0006] The fourth objective of this invention is to provide a vehicle.

[0007] To address the aforementioned problems, a first aspect of the present invention provides a State of Charge (SOC) calibration method, comprising: acquiring state parameter information of the charging and discharging circuit in which the battery cell is located; determining a target operating condition satisfied by the battery cell from at least two preset operating conditions based on the state parameter information, wherein each preset operating condition corresponds to a preset calibration strategy; and determining an SOC calibration value based on the target calibration strategy corresponding to the target operating condition.

[0008] According to the SOC calibration method of the present invention, based on at least two preset operating conditions, corresponding SOC calibration strategies can be provided for different operating conditions. The diverse calibration strategies improve the accuracy of SOC calibration and can avoid the problem of excessive cumulative error or even SOC value jump caused by the inability to accurately calibrate the SOC value over a long period of time.

[0009] In some embodiments, the status parameter information includes at least one of contactor status information and battery status information.

[0010] In some embodiments, the contactor status information includes at least one of the contactor switch status and the cumulative disconnection time of the contactor.

[0011] In some embodiments, the battery status information includes at least one of the following: terminal voltage, open-circuit voltage, current, state of charge (SOC), and temperature of the battery cell.

[0012] In some embodiments, determining the target operating condition satisfied by the battery cell from at least two preset operating conditions based on the state parameter information includes: obtaining the current change value of the battery cell within a first time threshold based on the current value; when the contactor switch is in the engaged state, the current change value of the battery cell within the first time threshold is less than or equal to a first current change threshold, and the terminal voltage value of the battery cell is within a target voltage range, determining that the target operating condition satisfied by the battery cell is a constant rate discharge operating condition.

[0013] In some embodiments, determining the target operating condition satisfied by the battery cell from at least two preset operating conditions based on the state parameter information includes: obtaining the current change value of the battery cell within a first time threshold based on the current value, and obtaining the terminal voltage change slope based on the terminal voltage value; when the contactor switch is in the engaged state, the current change value of the battery cell within the first time threshold is less than or equal to a first current change threshold, and the terminal voltage change slope is not less than the minimum value of the slope of the SOC-OCV relationship curve within the target voltage range, the target operating condition satisfied by the battery cell is determined to be a constant rate discharge operating condition.

[0014] In some embodiments, the target operating condition satisfied by the battery cell is determined from at least two preset operating conditions based on the state parameter information, including: when the contactor state is a first switching state and the cumulative disconnection time of the contactor is less than the target resting time, the target operating condition satisfied by the battery cell is determined to be a constant rate discharge operating condition, wherein the first switching state is a state of switching from disconnection to engagement.

[0015] In some embodiments, determining the SOC calibration value according to the target calibration strategy corresponding to the target operating conditions includes: obtaining a first open-circuit voltage calculation value of the battery cell based on the battery state information of the battery cell under the constant rate discharge operating conditions; and determining the SOC calibration value based on the first open-circuit voltage calculation value and a first preset correspondence.

[0016] In some embodiments, obtaining a first open-circuit voltage calculation value of the battery cell based on battery state information includes: acquiring the rate current parameter and internal resistance parameter of the battery cell; and obtaining the first open-circuit voltage calculation value based on the terminal voltage value of the battery cell, the rate current parameter, and the internal resistance parameter.

[0017] In some embodiments, obtaining the first open-circuit voltage calculation value based on the terminal voltage value of the battery cell, the rate current parameter, and the internal resistance parameter includes: obtaining an internal resistance voltage value based on the rate current parameter and the internal resistance parameter; and obtaining the first open-circuit voltage calculation value based on the terminal voltage value and the internal resistance voltage value.

[0018] In some embodiments, obtaining the rate current parameter and internal resistance parameter of the battery cell includes: obtaining the rate parameter of the battery cell based on the current value of the battery cell; and obtaining the rate current parameter based on the rate parameter.

[0019] In some embodiments, obtaining the rate current parameter and internal resistance parameter of the battery cell further includes: obtaining the internal resistance parameter based on the rate current parameter, the temperature value of the battery cell, and the SOC value of the battery cell.

[0020] In some embodiments, obtaining the rate current parameter and internal resistance parameter of the battery cell includes: obtaining the internal resistance parameter based on the current value of the battery cell and the terminal voltage value corresponding to the current value.

[0021] In some embodiments, the target operating condition satisfied by the battery cell is determined from at least two preset operating conditions based on the state parameter information, including: when the contactor switch is in the open state and the open circuit voltage value of the battery cell is within the target voltage range, the target operating condition satisfied by the battery cell is determined to be the static discharge operating condition.

[0022] In some embodiments, determining the target operating condition satisfied by the battery cell from at least two preset operating conditions based on the state parameter information includes: when the contactor switch state is a first transition state and the cumulative disconnection time of the contactor is greater than or equal to the target resting time corresponding to the temperature value of the battery cell, determining the target operating condition satisfied by the battery cell as a resting discharge operating condition, wherein the first transition state is a state of switching from disconnection to engagement.

[0023] In some embodiments, determining the SOC calibration value according to the target calibration strategy corresponding to the target operating condition includes: determining the SOC calibration value according to the open-circuit voltage value of the battery cell and a second preset correspondence under the static discharge operating condition.

[0024] In some embodiments, the target operating condition satisfied by the battery cell is determined from at least two preset operating conditions based on the state parameter information, including: when the contactor switch is in the energized state, the open circuit voltage of the battery cell is within the target voltage range, and the current values ​​of two adjacent motion steps are different, the target operating condition satisfied by the battery cell is determined to be a dynamically changing operating condition.

[0025] In some embodiments, determining the target operating condition satisfied by the battery cell from at least two preset operating conditions based on the state parameter information includes: obtaining the current change value of the battery cell within a second time threshold based on the current value of the battery cell; when the contactor switch is in the engaged state, the open-circuit voltage value of the battery cell is within the target voltage range, and the current change value of the battery cell within the second time threshold is greater than the second current change threshold, determining that the target operating condition satisfied by the battery cell is a dynamically changing operating condition.

[0026] In some embodiments, determining the SOC calibration value according to a target calibration strategy corresponding to the target operating conditions includes: obtaining a second open-circuit voltage calculation value of the battery cell based on the battery state information and equivalent circuit model of the battery cell under the dynamically changing operating conditions; and determining the SOC calibration value based on the second open-circuit voltage calculation value and a third preset correspondence.

[0027] In some embodiments, obtaining the second open-circuit voltage calculation value of the battery cell based on the battery state information and equivalent circuit model of the battery cell includes: obtaining an estimated terminal voltage value, an estimated impedance value, and an estimated open-circuit voltage value based on the terminal voltage value, the current value, and the equivalent circuit model of the battery cell; when the difference between the estimated terminal voltage value and the detection terminal voltage value is within a preset deviation range, the estimated impedance value is within the offline impedance range, and the estimated open-circuit voltage value is within the normal open-circuit voltage value range, the estimated open-circuit voltage value is used as the second open-circuit voltage calculation value.

[0028] In some embodiments, the SOC-OCV relationship curve of the battery cell has a first voltage plateau period, a second voltage plateau period, and a dual voltage plateau interval period, wherein the dual voltage plateau interval period is the curve interval from the end of the first voltage plateau period to the beginning of the second voltage plateau period; and the target voltage range is the voltage interval between the lower voltage limit of the first voltage plateau period and the upper voltage limit of the second voltage plateau period.

[0029] A second aspect of the present invention provides an electronic device, comprising: at least one processor; a memory communicatively connected to the at least one processor; the memory storing a computer program executable by the at least one processor, wherein the at least one processor executes the computer program to implement the SOC calibration method described in the above embodiments.

[0030] According to the electronic device of the present invention, the corresponding SOC calibration program can be stored in the memory. When implementing the SOC calibration method, the processor runs the program in the memory, obtains the circuit state information of the charging and discharging circuit where the battery cell is located, determines the SOC target calibration strategy, and after the battery state information of the battery cell meets the calibration conditions of the target SOC calibration strategy, the SOC value of the battery cell is calibrated by the corresponding SOC calibration strategy.

[0031] A third aspect of the present invention provides a non-volatile readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed, implements the SOC calibration method described in the above embodiments.

[0032] A fourth aspect of the present invention provides a vehicle including a battery cell and the electronic device described in the above embodiments, the electronic device being used to perform SOC calibration on the battery cell.

[0033] According to the vehicle of the present invention, the electronic device obtains the loop state information of the charging and discharging circuit where the battery cell is located, determines the target SOC calibration strategy through the loop state information, and calibrates the SOC value of the battery cell through the corresponding SOC calibration strategy after the battery state information of the battery cell meets the calibration conditions of the target SOC calibration strategy. Based on at least two preset operating conditions, corresponding SOC calibration strategies can be provided for different operating conditions. The diverse calibration strategies improve the accuracy of SOC calibration and can avoid the problem of excessive cumulative error or even SOC value jump due to the inability to accurately calibrate the SOC value for a long time.

[0034] Furthermore, it can calibrate the SOC value of battery cells during the dual-voltage plateau interval, improving the accuracy of the SOC value of battery cells. This solves the problem that SOC calibration cannot be intervened during the dual-voltage plateau interval of battery cells, and avoids the problem of excessive cumulative error or even SOC value jump caused by long-term inaccurate SOC value calibration.

[0035] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart of a SOC calibration method according to an embodiment of the present invention; Figure 2 This is a graph showing the relationship between the state of charge (SOC) and the open volume (OCV) of a battery cell discharge according to an embodiment of the present invention. Figure 3 This is a flowchart of a second SOC calibration strategy according to an embodiment of the present invention; Figure 4 This is a flowchart of voltage plateau interval SOC calibration according to an embodiment of the present invention; Figure 5 This is a structural block diagram of an electronic device according to an embodiment of the present invention; Figure 6 This is a structural block diagram of a vehicle according to an embodiment of the present invention.

[0037] Figure label: 200 vehicles; Battery cell 201; Electronic device 100; Processor 101; Memory 102. Detailed Implementation

[0038] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0039] The first aspect of the present invention provides a SOC calibration method that can calibrate the SOC value of a battery cell during the dual-voltage plateau interval, thereby improving the accuracy of the SOC value of the battery cell. This solves the problem that SOC calibration cannot be performed on the battery cell during the dual-voltage plateau interval, and avoids the problem of excessive cumulative error or even SOC value jump caused by the long-term inability to accurately calibrate the SOC value.

[0040] The following is for reference. Figure 1 A SOC calibration method according to an embodiment of the first aspect of the present invention is described, such as... Figure 1 As shown, the method includes at least steps S11 to S13.

[0041] Step S11: Obtain the state parameter information of the charging and discharging circuit where the battery cell is located.

[0042] The status parameter information may include the on / off status of the contactor in the charging / discharging circuit, and battery status information such as current value, temperature value, and SOC value.

[0043] Step S12: Based on the state parameter information, determine the target operating conditions that the battery cell must meet from at least two preset operating conditions, wherein each preset operating condition corresponds to a preset calibration strategy.

[0044] In this embodiment of the invention, multiple preset operating conditions can be configured according to different discharge states of the battery, such as the battery being in a static discharge state, a constant rate discharge state, or a dynamic change state. For each preset operating condition, a better SOC calibration strategy can be adopted.

[0045] Step S13: Determine the SOC calibration value according to the target calibration strategy corresponding to the target operating conditions, so as to perform SOC calibration of the battery cell.

[0046] Specifically, in some embodiments, the battery cell can be a battery pack or a single battery cell. For example, a single battery cell may include a lithium iron manganese phosphate cell. State of Charge (SOC) is the ratio of the remaining capacity of a battery after a period of use or long-term storage to its capacity in a fully charged state, usually expressed as a percentage. Its value ranges from 0 to 100. When SOC=0, it indicates that the battery is fully discharged; when SOC=100, it indicates that the battery is fully charged. SOC is crucial for managing battery performance, predicting battery life, and protecting the battery from overcharging or over-discharging. When the battery cell operates in the charging / discharging circuit, a target SOC calibration strategy is determined based on the operating conditions satisfied by the circuit state information. Different target SOC calibration strategies are selected for different circuit state information. A SOC calibration value is obtained based on the target SOC calibration strategy, and the SOC value of the battery cell is calibrated based on the SOC calibration value. For example, replacing the current SOC value of the battery cell with the SOC calibration value can ensure the accuracy of the SOC value.

[0047] For example, in some embodiments, the SOC calibration strategy may include three different calibration strategies. Based on the acquired state parameter information, it is determined whether the current battery cell is in the dual-voltage plateau interval period of the battery cell, such as a lithium iron phosphate cell. If the determination result is yes, it is determined whether the first calibration condition is met based on the parameter information. If it is met, the current battery pack SOC true value is calibrated to the corresponding calibration value according to the first calibration strategy. If the first calibration condition is not met but the second calibration condition is met based on the parameter information, the current battery pack SOC true value is calibrated to the corresponding calibration value according to the second calibration strategy. If the current battery parameter information does not meet the first and second calibration conditions but meets the third calibration condition, the current battery pack SOC true value is calibrated to the corresponding calibration value according to the third calibration strategy. This invention uses three different calibration strategies to calibrate the SOC of lithium iron phosphate battery cells, improving the accuracy of power battery SOC estimation and addressing the technical problem of poor SOC calibration results for cells with dual-voltage plateau characteristics.

[0048] The SOC calibration method of this invention is based on at least two preset operating conditions and can provide corresponding SOC calibration strategies for different operating conditions. The diverse calibration strategies improve the accuracy of SOC calibration and can avoid the problem of excessive cumulative error or even SOC value jump due to long-term inaccurate SOC value calibration.

[0049] In the embodiments of the present invention, the calibration is mainly performed on the SOC of the battery cell during the dual voltage plateau interval, because the SOC changes significantly during the dual voltage plateau interval, and the SOC value of the battery cell is prone to jumps, resulting in inaccuracies.

[0050] Specifically, after obtaining the loop state information of the charging and discharging circuit where the battery cell is located, the target SOC calibration strategy is determined based on the loop state information. At the same time, the battery state information of the battery cell is judged. After the battery state information of the battery cell meets the calibration conditions of the target SOC calibration strategy, the target SOC calibration strategy is executed to obtain the SOC calibration value of the battery cell. When the target SOC calibration strategy is executed, the battery state information is in the dual voltage plateau interval of the battery cell.

[0051] For example, a voltage plateau period refers to a relatively stable phase in the battery's voltage curve during charging and discharging. The voltage value in this phase is relatively stable and does not change significantly with the charging and discharging process. Some types of batteries, such as lithium manganese iron phosphate batteries, exhibit two distinct voltage plateaus during charging and discharging. These plateaus represent regions where the battery's electrochemical reactions are stable, corresponding to specific stages of chemical reactions within the battery. The dual voltage plateau interval refers to the transition period during which the battery voltage shifts from one plateau to another. During this period, the battery voltage is unstable, and the internal chemical reactions gradually change.

[0052] According to the SOC calibration method of the present invention, by acquiring the loop state information of the charging and discharging circuit where the battery cell is located, a target SOC calibration strategy is determined based on the loop state information. When the battery state information of the battery cell meets the calibration conditions of the target SOC calibration strategy, the SOC value of the battery cell is calibrated by the corresponding SOC calibration strategy. This method can calibrate the SOC value of the battery cell during the dual voltage plateau interval, improve the accuracy of the battery cell SOC value, solve the problem that SOC calibration cannot be intervened during the dual voltage plateau interval, and avoid the problem of excessive cumulative error or even SOC value jump caused by the long-term inaccurate calibration of the SOC value.

[0053] In this embodiment, the state parameter information of the charging and discharging circuit where the battery cell is located may include at least one of the contactor state information and the battery state information.

[0054] Furthermore, the contactor status information may include the contactor switch status and the contactor's disconnection duration. The contactor switch status may include the engaged state, the disconnected state, and the transition state from disconnection to engagement, etc.

[0055] Furthermore, the battery status information may include at least one of the following: the current value, terminal voltage value, open circuit voltage value, temperature value, and SOC value of the battery cell, as well as other relevant status information of the battery cells.

[0056] In some embodiments, determining the target operating condition satisfied by the battery cell from at least two preset operating conditions based on state parameter information includes: obtaining the current change value of the battery cell within a first time threshold based on the current value; and determining the target operating condition satisfied by the battery cell as a static discharge operating condition when the contactor of the charging / discharging circuit containing the battery cell is in an open state and the open-circuit voltage value of the battery cell is within a target voltage range. In one embodiment, the target voltage range can be the dual-voltage plateau interval of the battery cell.

[0057] Alternatively, in some embodiments, when the contactor of the charging and discharging circuit where the battery cell is located is in a first switching state, and the cumulative disconnection time of the contactor is greater than or equal to the target resting time corresponding to the temperature value of the battery cell, the target operating condition satisfied by the battery cell is determined to be the resting discharge operating condition, wherein the first switching state is the state of switching from disconnection to engagement.

[0058] The target settling time can be determined based on the temperature of the battery cell. A corresponding settling time is set for different battery temperature values ​​because different temperatures have different effects on the internal materials of the battery cell. The target settling time is determined by the temperature value to ensure the accuracy of judging whether the battery cell is in a settling state.

[0059] The cumulative disconnection time can be the time between the detection of the contactor disconnection signal and the detection of the contactor engagement signal.

[0060] The target voltage range may include the dual voltage plateau interval of the battery cell.

[0061] That is, when the battery cell is in the off state and the open circuit voltage is in the interval between the two voltage platforms, or when the contactor changes from off to on and the cumulative time of contactor off is greater than the target resting time corresponding to the temperature value, the SOC target calibration strategy is the first SOC calibration strategy. The first SOC calibration strategy corresponds to the resting calibration condition of the battery cell, that is, the target condition that the battery cell meets is the resting discharge condition.

[0062] Specifically, circuit status information is used to determine the circuit's on / off state. Contactor status information is obtained through processing by sensors within the battery pack. The cumulative contactor disconnection time is calculated using a timing chip within the battery pack and contactor disconnection / closure status information. The battery cell temperature value is obtained through processing by sensors within the battery pack. When the contactor is in an open state in the charging / discharging circuit, or when it transitions from open to closed and the cumulative contactor disconnection time exceeds the target resting time corresponding to the temperature value, the first SOC calibration strategy is used for target SOC calibration. In other words, when the battery cell is in resting calibration condition, the battery cell is calibrated using the first SOC calibration strategy. The target resting time for the battery cell varies at different temperatures. Taking a minimum battery cell temperature of not less than 15°C as an example, when the contactor is in an open state or transitions from open to closed and the cumulative contactor disconnection time exceeds the target resting time corresponding to 15°C, the first SOC calibration strategy is used.

[0063] In some embodiments, for static discharge conditions, the open-circuit voltage of the battery cell is within a target voltage range, for example, the battery status information is within the dual voltage plateau interval of the battery cell, including: the open-circuit voltage is between the lower voltage limit of the first voltage plateau period of the battery cell and the upper voltage limit of the second voltage plateau period of the battery cell.

[0064] Specifically, when the contactor is open, the open-circuit voltage of the battery cell is obtained by the sensor inside the battery cell after being collected and processed. The battery cell includes dual voltage platforms, and the open-circuit voltage is between the voltage intervals of the dual voltage platforms.

[0065] like Figure 2 As shown in the figure, the open-circuit voltage curve of the lithium iron manganese phosphate (LMP) battery cell has two voltage plateaus. The open-circuit voltage of the first voltage plateau is around 4.0V, and the open-circuit voltage of the second voltage plateau is about 3.5V. The minimum voltage of the first voltage plateau is greater than the maximum voltage of the second voltage plateau. The interval between the two voltage plateaus is the corresponding double voltage plateau interval. Specifically, it can be determined by judging whether the current open-circuit voltage of the battery cell is between the minimum voltage value V1 of the first voltage plateau and the maximum voltage V2 of the second voltage plateau.

[0066] In some embodiments, under static discharge conditions, the SOC calibration value is determined based on the open-circuit voltage of the battery cell and a second preset correspondence. In these embodiments, the second preset correspondence may be an SOC-OCV mapping relationship between open-circuit voltage and SOC value, or other applicable correspondences.

[0067] For example, the SOC calibration value is obtained by querying the target SOC-OCV mapping relationship based on the open-circuit voltage value. The target SOC-OCV mapping relationship is determined based on the temperature value of the battery cell.

[0068] Specifically, since different open-circuit voltages correspond to different states of charge (SOC), a SOC-OCV mapping relationship is generated based on the open-circuit voltage and SOC. This SOC-OCV mapping relationship differs at different temperatures. The SOC calibration value is obtained by querying the target SOC-OCV mapping relationship based on the current temperature. The system then determines whether the first SOC calibration strategy is met based on the current battery state parameters. If the current battery pack contactor state is open or transitioning from open to closed, the system determines whether the battery cell static calibration method is met based on the battery pack temperature, battery cell voltage, and contactor open cumulative time information. After the contactor state information transitions from open to closed for a certain period, the battery pack contactor open cumulative time information is cleared. Similarly, the contactor open cumulative time information is cleared 3 seconds after the contactor state transitions from open to closed.

[0069] For example, based on the voltage state information corresponding to the current battery cell, when the battery pack contactor is in the open state or transitions from open to closed, the cumulative time of the current contactor being open is not less than the resting time of the open circuit voltage measurement in the OCV curve at the corresponding temperature. Taking the lowest temperature of the battery cell in the battery pack as not less than 15℃ as an example, the first SOC calibration strategy is used to calibrate the estimated SOC value of the current battery pack to the corresponding SOC-OCV lookup table SOC value.

[0070] In some embodiments, determining the target operating condition satisfied by the battery cell from at least two preset operating conditions based on state parameter information includes: obtaining the current change value of the battery cell within a first time threshold based on the current value; when the contactor of the charging and discharging circuit where the battery cell is located is in the engaged state, the current change value of the battery cell within the first time threshold is less than or equal to the first current change threshold, and the terminal voltage value of the battery cell is within the target voltage range, determining that the target operating condition satisfied by the battery cell is a constant rate discharge operating condition.

[0071] Among them, the constant rate discharge condition corresponds to a state in which the current of the battery cell changes slightly, which is approximately the same as a constant current.

[0072] In other embodiments, when the contactor of the charging and discharging circuit where the battery cell is located is in a first switching state and the cumulative disconnection time of the contactor is less than the target resting time, the target operating condition satisfied by the battery cell is determined to be a constant rate discharge operating condition, wherein the first switching state is a state of switching from disconnection to engagement.

[0073] The target settling time can be determined based on the temperature of the battery cell. A corresponding settling time is set for different battery temperature values ​​because different temperatures have different effects on the internal materials of the battery cell. The target settling time is determined by the temperature value to ensure the accuracy of judging whether the battery cell is in a settling state.

[0074] The cumulative disconnection time can be the time between the detection of the contactor disconnection signal and the detection of the contactor engagement signal.

[0075] Alternatively, in some embodiments, the target operating condition satisfied by the battery cell is determined from at least two preset operating conditions based on the state parameter information, including: obtaining the current change value of the battery cell within a first time threshold based on the current value, and obtaining the terminal voltage change slope based on the terminal voltage value; when the contactor switch is in the engaged state, the current change value of the battery cell within the first time threshold is less than or equal to a first current change threshold, and the terminal voltage change slope is not less than the minimum value of the slope of the SOC-OCV relationship curve within the target voltage range, the target operating condition satisfied by the battery cell is determined to be a constant rate discharge operating condition.

[0076] That is, when the contactor is in the engaged state, or when it is in the transition state from open to engaged and the cumulative time of contactor disconnection is less than the target resting time corresponding to the temperature value, or when the slope of the terminal voltage change meets the calibration conditions, the target SOC calibration strategy is the second SOC calibration strategy, which can correspond to the constant rate discharge condition of the battery cell.

[0077] Specifically, if the current charging and discharging circuit status parameters indicate that the first calibration strategy (i.e., the static discharge condition) is not met, then the current current, voltage, and temperature of the battery cell are assessed to determine whether the second SOC calibration strategy (i.e., the constant rate discharge condition) is met. Under the constant rate discharge condition, the contactor switch is either in the energized state or the contactor switch transitions from open to energized and the cumulative contactor disconnection time is less than the static time measured by the open-circuit voltage in the OCV curve at the corresponding temperature. The target static time for the battery cell varies at different temperatures. For example, if the minimum temperature of the battery cell is not less than 15°C, and the contactor switch is in the energized state or transitions from open to energized and the cumulative contactor disconnection time is less than the target static time corresponding to 15°C, the second SOC calibration strategy is adopted. When the second SOC calibration strategy is adopted, the contactor switch is in the closed state.

[0078] In some embodiments, the state parameter information also includes the current value of the battery cell, which is obtained by the sensor in the battery cell after acquisition and processing. The first time threshold can be understood as the detection time set under constant rate discharge conditions, and the first current value change threshold can be understood as the maximum value that the current value can fluctuate under constant rate discharge conditions. The current value change is not greater than the first current value change threshold within the first time threshold under constant rate discharge conditions, and the current battery cell is located in the dual voltage plateau interval.

[0079] In some embodiments, under constant rate discharge conditions, the terminal voltage value of the battery cell is within the target voltage range, for example, the battery state information is within the dual voltage plateau interval of the battery cell, including: during the discharge process, the slope of the change in the terminal voltage value is not less than the minimum value of the slope of the SOC-OCV curve within the dual voltage plateau interval of the battery cell.

[0080] Specifically, under constant rate discharge conditions, the terminal voltage value of the battery cell is obtained. When the battery state information is in the interval between the two voltage plateaus of the battery cell, the slope of the change in the terminal voltage value of the battery cell during the discharge process is not less than the minimum slope of ΔOCV corresponding to ΔSOC during the interval between the two voltage plateaus. The change in the current value of the battery cell within the first time threshold is not greater than the first current value change threshold. Taking 30s as an example, the first time threshold means that the current parameter of the battery cell tends to the constant current discharge state or the change range of the current parameter within the first time threshold does not exceed 0.01C. The slope of ΔOCV corresponding to the interval between the two voltage plateaus, ΔSOC, can be obtained by curve fitting and the curve slope corresponding to SOC during the interval between the two voltage plateaus is obtained based on the partial derivative of the curve.

[0081] In some embodiments, under constant rate discharge conditions, determining the SOC calibration value according to a target calibration strategy corresponding to the target conditions includes: under constant rate discharge conditions, obtaining a first open-circuit voltage calculation value of the battery cell based on the battery state information of the battery cell; and determining the SOC calibration value based on the first open-circuit voltage calculation value and a first preset correspondence.

[0082] Specifically, the first open-circuit voltage of the battery cell can be calculated based on the battery status information; the SOC calibration value can be obtained by querying the target SOC-OCV mapping relationship of the battery cell based on the first open-circuit voltage calculation value. The target SOC-OCV mapping relationship is determined based on the temperature value of the battery cell.

[0083] Specifically, since different open-circuit voltages correspond to different states of charge, a SOC-OCV mapping relationship is generated based on the open-circuit voltage and the state of charge. The SOC-OCV mapping relationship is different at different temperatures. The SOC calibration value is obtained by querying the target SOC-OCV mapping relationship based on the current temperature. The first open-circuit voltage calculation value can be understood as the open-circuit voltage value calculated under the second SOC calibration strategy. The first open-circuit voltage calculation value of the battery cell is calculated based on the obtained battery state information. The SOC calibration value is obtained by querying the target SOC-OCV mapping relationship of the battery cell through the first open-circuit voltage calculation value.

[0084] In some embodiments, the rate current parameter and internal resistance parameter of the battery cell are obtained; a first open-circuit voltage is calculated based on the battery cell's terminal voltage value, rate current parameter, and internal resistance parameter. That is, the first open-circuit voltage is calculated based on the battery cell's terminal voltage value, rate current parameter, and internal resistance parameter; the rate current parameter and internal resistance parameter are obtained based on battery state information.

[0085] Specifically, the battery state information obtained under constant rate discharge conditions includes the terminal voltage value of the battery cell, the rate current value parameter of the battery cell, and the internal resistance parameter. The first open-circuit voltage value of the battery cell is calculated based on the terminal voltage value of the battery cell, the rate current value parameter of the battery cell, and the internal resistance parameter.

[0086] Further, the internal resistance voltage value is obtained based on the multiplier current parameter and the internal resistance parameter; the first open-circuit voltage calculation value is obtained based on the terminal voltage value and the internal resistance voltage value. For example, the first open-circuit voltage calculation value can be the sum of the terminal voltage value, the internal resistance voltage value, and the compensation voltage value.

[0087] In some embodiments, the rate parameter of the battery cell is obtained based on the current value of the battery cell; and the rate current parameter is obtained based on the rate parameter. For example, the rate parameter of the battery cell is obtained based on the current value and the rated capacity parameter of the battery cell; and the rate current parameter is obtained based on the rated capacity parameter and the rate parameter.

[0088] For example, the rate parameter is obtained by dividing the current value of the battery cell by the rated capacity parameter according to a preset rounding method, while the rate current value parameter is obtained based on the rated capacity parameter and the rate parameter of the battery cell.

[0089] Specifically, the rate parameter is calculated by dividing the current rate parameter by the rated capacity parameter, retaining two significant digits after the decimal point, with the second decimal digit being 0 or 5, to obtain the rate parameter under this condition. Then, the calculated rate parameter is multiplied by the capacity of the battery cell to obtain the rate current value parameter under this condition.

[0090] For example, current ratio is an important parameter that indicates the battery's charging and discharging capacity. Specifically, current ratio refers to the ratio of the current required to charge or discharge the battery to its rated capacity within a specified time, usually represented by the letter C. Calculating the current ratio parameter for the current capacity of a battery cell, taking a battery cell capacity of 100AH ​​and a current parameter of 22A as an example, the actual calculated current ratio is 0.22C. After calculating according to the ratio parameter, the result is 0.2C. The rounding method for the ratio parameter is based on the difference between the second significant digit after the decimal point and the digit 0 or 5. For example: less than 0.225 is rounded to 0.2, greater than 0.225 but less than 0.275 is rounded to 0.25, and greater than 0.275 is rounded to 0.3. Based on the obtained ratio parameter, the current ratio parameter for this state is calculated to be 0.2 * 100 = 20A.

[0091] In some embodiments, the internal resistance parameter is obtained based on the rate current parameter, the temperature value of the battery cell, and the SOC value of the battery cell; or, the internal resistance parameter is obtained based on the current value of the battery cell and the terminal voltage value corresponding to the current value, wherein the current value can be a pulse current value.

[0092] For example, the battery status information also includes the SOC value of the battery cell; the internal resistance parameter is obtained by querying the first preset mapping relationship based on the rate current value parameter, the temperature value of the battery cell and the SOC value of the battery cell.

[0093] The first preset mapping relationship is the mapping relationship between the rate current value parameter, the temperature value of the battery cell, and the SOC value and internal resistance parameter of the battery cell.

[0094] Specifically, the SOC value and temperature value of the battery cell are obtained based on the battery status information. Then, the rate current value parameter is calculated. The battery internal resistance parameter corresponding to the current SOC value, temperature value and rate current value parameter of the battery cell is obtained by querying the first preset mapping relationship table through the current temperature value, SOC value and rate current value parameter of the battery cell.

[0095] For example, the internal resistance parameter is calculated based on the pulse current value of the battery cell and the corresponding terminal voltage value; the pulse current value is obtained by querying the second preset mapping relationship based on the SOC value and temperature value of the battery cell. The second preset mapping relationship is the mapping relationship between the SOC value, the temperature value of the battery cell and the pulse current value.

[0096] Specifically, the internal resistance parameter can also be calculated based on the pulse current value of the battery cell and the corresponding terminal voltage value. The pulse current value can be obtained by querying a second preset mapping relationship based on the SOC value and temperature value of the battery cell. First, the SOC value and temperature value of the battery cell are obtained based on the battery state information, and then the pulse current value is obtained by querying the second preset mapping relationship. Within different SOC value ranges and different temperature value ranges, a pulse current value is applied, and the terminal voltage change value under different pulse current values ​​is obtained. The current internal resistance parameter of the battery cell is calculated based on the pulse current value, the current temperature, and the SOC value.

[0097] In some embodiments, in the second preset mapping relationship, the range of the pulse current value is determined by dividing the capacity state of the battery cell into different intervals; the SOC value of the dual voltage plateau period of the corresponding battery cell is greater than the SOC value of the dual voltage plateau interval period of the corresponding battery cell.

[0098] Specifically, when obtaining the second preset mapping table, the pulse current rate range can be divided into different intervals according to the capacity state of the battery cell. The size of the SOC interval can be adjusted according to whether it is in the dual voltage plateau interval period. A larger value can be taken during the dual voltage plateau period, and a smaller value can be taken during the dual voltage plateau interval period. The SOC value during the dual voltage plateau period is greater than the SOC value of the corresponding battery cell during the dual voltage plateau interval period. For example, the SOC interval is 5% during the dual voltage plateau period and 2% during the dual voltage plateau interval period. The pulse current value ranges are 0.05, 0.1C, 0.15C, 0.2C, 0.3C, 0.4C, 0.5C, 0.6C, 0.7C, 0.8C, 0.9C, and 1C, respectively.

[0099] In some embodiments, the first open-circuit voltage of the battery cell is the sum of the terminal voltage of the battery cell, the internal resistance voltage of the battery cell, and the compensation voltage, wherein the internal resistance voltage is the product of the rate current parameter and the internal resistance parameter.

[0100] Specifically, the rate current value parameter is first obtained through the rated capacity parameter and rate parameter of the battery cell. The internal resistance parameter is calculated through the pulse current value and the corresponding terminal voltage value of the battery cell. The rate current value parameter and the internal resistance parameter are multiplied to obtain the internal resistance voltage value. Then, the terminal voltage value, the internal resistance voltage value, and the compensation voltage value of the battery cell are added to obtain the first open circuit voltage calculation value. The compensation part of the first open circuit voltage calculation value is optional. When the lookup interval in the preset table is large or the battery cell capacity is high, such as when the voltage plateau interval pulse current interval in the second preset mapping relationship table is 0.1C or the battery cell capacity is greater than 150AH, the first open circuit voltage calculation value can be compensated according to different rules based on the specific test results of the battery.

[0101] The following is for reference. Figure 3 The SOC calibration steps under constant rate discharge conditions in this embodiment of the invention are illustrated with an example, as follows.

[0102] Step S3: The battery cell status information satisfies the second SOC calibration strategy.

[0103] Specifically, the current state information of the battery cell is obtained, including current value, voltage value, temperature value, contactor switch status and contactor switch open cumulative time information. After the battery cell state information meets the constant rate discharge condition, i.e. the second SOC calibration strategy, calibration is performed using the second SOC calibration strategy.

[0104] Step S4: Calculate the rate current value parameter after mapping the current of the current cell.

[0105] Specifically, the calculation method is to divide the current parameter by the rated capacity parameter, retain two significant digits after the decimal point, and the second digit after the decimal point is 0 or 5 to obtain the rate parameter in this state. Then, the above rate parameter is multiplied by the capacity of the battery cell to obtain the mapped rate current value parameter in this state.

[0106] Step S5: Based on the rate current value, temperature value, and SOC value, look up the preset mapping table to obtain the battery cell internal resistance parameter under the current state.

[0107] Step S6, First open-circuit voltage = terminal voltage value + internal resistance parameter * multiplier current value parameter + compensation voltage.

[0108] Step S7: Based on the calculated first open-circuit voltage value, look up the SOC-OCV table to obtain the estimated SOC value under the current state.

[0109] Specifically, the estimated SOC value of the battery cell corresponding to the current parameter state is obtained by looking up the SOC-OCV table based on the first open-circuit voltage value calculated in step S7.

[0110] In some embodiments, the target operating condition satisfied by the battery cell is determined from at least two preset operating conditions based on state parameter information, including: when the contactor of the charging and discharging circuit where the battery cell is located is in the energized state, the open circuit voltage value of the battery cell is within the target voltage range, and the current values ​​of two adjacent motion step lengths are different, wherein the motion step length is the time interval for calling the calibration power function, and the target operating condition satisfied by the battery cell is determined to be a dynamically changing operating condition.

[0111] Alternatively, in some embodiments, the target operating condition satisfied by the battery cell is determined from at least two preset operating conditions based on the state parameter information, including: obtaining the current change value of the battery cell within a second time threshold based on the current value of the battery cell; when the contactor switch is in the engaged state, the open circuit voltage value of the battery cell is within the target voltage range, and the current change value of the battery cell within the second time threshold is greater than the second current change threshold, the target operating condition satisfied by the battery cell is determined to be a dynamically changing operating condition.

[0112] In the case of dynamic operating conditions, the contactor is in the energized state. Therefore, the switching voltage value of the battery cell is the open-circuit voltage calculated based on the battery status information.

[0113] In some embodiments, when the battery state information is in the dual voltage plateau interval of the battery cell but the battery state information does not meet the static discharge condition and the constant rate discharge condition, and the contactor is in the engaged state, the SOC target calibration strategy is the third SOC calibration strategy, which corresponds to the dynamic change condition of the battery cell.

[0114] Specifically, the current battery status information is obtained, and it is determined that the battery status information is in the dual-voltage plateau interval of the battery cell, and the battery status information does not meet the calibration conditions of the static discharge condition and the constant rate discharge condition. At this time, the contactor status is judged. If the contactor status is in the engaged state, the SOC target calibration strategy is the third SOC calibration strategy, which meets the dynamic change condition conditions. The third SOC calibration strategy condition means that when the first SOC calibration strategy and the second SOC calibration strategy are not met, and the current current value, voltage value, and temperature value of the battery cell meet the third calibration strategy condition, the current true SOC estimate is calibrated according to the third SOC calibration strategy. The third SOC calibration strategy corresponds to the dynamic change condition conditions of the battery cell. Under this condition, the current changes significantly compared to the second SOC calibration strategy.

[0115] In some embodiments, under dynamically changing operating conditions, the calibration conditions further include battery state information satisfying the dynamic change conditions of the battery cell; the dynamic change conditions include that when the battery cell is in a non-charging state, the current values ​​of two adjacent running steps are different, the running step is the time interval when the calibration function is called once, or the change in the current value of the battery cell within a second time threshold is greater than the second current value change threshold.

[0116] Specifically, when the battery cell is discharging in the contactor state, the current and voltage values ​​meet the dynamic change conditions. When the battery cell is not charging, the current values ​​of two adjacent operating steps are different, or the change in the current parameter value within the second time threshold is greater than the second current value change threshold. The second time threshold can be understood as the detection time set under the third SOC calibration strategy, and the second current value change threshold can be understood as the maximum value that the current value can fluctuate under the third SOC calibration strategy. The operating step refers to the time interval when the calibration function is called once. Taking the time threshold of the third SOC calibration strategy as 3s and the second current value change threshold as 5A as an example, when the calibration function is called twice, under the non-charging condition, the change in the current status information value is not less than 1A, or the change in current is greater than 5A within 3s, and when the discharge positive current increases, the voltage parameter decreases, and when the positive current parameter decreases, the voltage parameter increases. This can be determined as meeting the third SOC calibration strategy, that is, the battery cell meets the dynamic change condition conditions.

[0117] In some embodiments, under dynamically changing operating conditions, the calculated value of the second open-circuit voltage of the battery cell is within the target voltage range, including: the calculated value of the second open-circuit voltage of the battery cell is between the lower limit of the voltage of the first voltage plateau period of the battery cell and the upper limit of the voltage of the second voltage plateau period of the battery cell.

[0118] Specifically, the second open-circuit voltage calculation value can be understood as the open-circuit voltage value calculated under the third SOC calibration strategy. In the third SOC calibration strategy, the second open-circuit voltage calculation value calculated by the third SOC calibration strategy is less than the lower limit of the voltage of the first voltage plateau period, greater than the upper limit of the voltage of the second voltage plateau period, and is between the lower limit of the voltage of the first voltage plateau period of the battery cell and the upper limit of the voltage of the second voltage plateau period of the battery cell.

[0119] For example, when the battery state information meets the dynamically changing operating conditions, the current second open-circuit voltage is calculated based on the current battery cell current, voltage, temperature, and RC equivalent circuit model. Figure 2 As shown, the calculated value of the second open-circuit voltage is between the minimum voltage value V1 of the first voltage plateau period and the maximum voltage V2 of the second voltage plateau period.

[0120] In an embodiment, such as Figure 2 As shown, the SOC-OCV relationship curve of the battery cell has a first voltage plateau period, a second voltage plateau period, and a dual voltage plateau interval period. The dual voltage plateau interval period is the curve interval from the end of the first voltage plateau period to the beginning of the second voltage plateau period. The target voltage range is the voltage interval between the lower voltage limit of the first voltage plateau period and the upper voltage limit of the second voltage plateau period. In some embodiments, the calculated value of the second open-circuit voltage is obtained through an equivalent circuit model of the battery cell, with the equivalent circuit model taking battery state information as input. That is, the calculated value of the second open-circuit voltage is obtained based on the battery state information of the battery cell and the equivalent circuit model.

[0121] Specifically, for battery cells that meet dynamically changing operating conditions, an equivalent circuit model of the battery cell is established. The SOC value of the battery cell under the current battery parameter conditions is obtained through parameter identification methods or combined with state-space filtering methods. The equivalent circuit model of the battery cell is established, usually an RC equivalent circuit model. Optional equivalent circuit models include zero-order, second-order, and multi-order equivalent circuit models. Based on the established RC equivalent circuit model and the battery state information parameters, the model parameters in the circuit model are identified. Based on the identified model parameters and the battery cell voltage value, the current SOC value of the battery cell is obtained.

[0122] In some embodiments, under dynamically changing operating conditions, the SOC calibration value is determined based on the calculated value of the second open-circuit voltage and the third preset correspondence.

[0123] The third preset correspondence can be the correspondence between the calculated value of the second open-circuit voltage and the SOC value of the battery cell. For example, it can be obtained by querying the target SOC-OCV mapping relationship of the battery cell based on the calculated value of the second open-circuit voltage. The target SOC-OCV mapping relationship is determined based on the temperature value of the battery cell.

[0124] Specifically, since different open-circuit voltages correspond to different states of charge, a SOC-OCV mapping relationship is generated based on the open-circuit voltage and the state of charge. The SOC-OCV mapping relationship is different at different temperatures. The SOC calibration value is obtained by querying the target SOC-OCV mapping relationship based on the current temperature. The second open-circuit voltage of the battery cell is calculated based on the obtained battery state information. The SOC calibration value is obtained by querying the target SOC-OCV mapping relationship of the battery cell through the second open-circuit voltage calculation value.

[0125] For example, if the current battery state information meets the dynamic changing operating conditions, then the third SOC calibration strategy is adopted. That is, the current current value and voltage value of the battery cell are used as the input signal of the RC equivalent circuit model. The estimated values ​​of impedance, terminal voltage and open circuit voltage of the circuit model are obtained by parameter identification method and filtered. Based on the difference between the estimated voltage and the battery cell voltage parameter, the impedance parameter and the effective value of the open circuit voltage, the current SOC value is obtained by looking up the SOC-OCV relationship curve. When the OCV value is in the voltage plateau interval, the third SOC calibration strategy is used to calibrate the current SOC value.

[0126] In some embodiments, obtaining the second open-circuit voltage calculation value of the battery cell based on the battery state information and equivalent circuit model of the battery cell includes: obtaining the estimated terminal voltage value, the estimated impedance value, and the estimated open-circuit voltage value based on the terminal voltage value, current value, and equivalent circuit model of the battery cell; when the difference between the estimated terminal voltage value and the detected terminal voltage value is within a preset deviation range, the estimated impedance value is within the offline impedance range, and the estimated open-circuit voltage value is within the normal open-circuit voltage value range, the estimated open-circuit voltage value is used as the second open-circuit voltage calculation value.

[0127] Specifically, the effective second open-circuit voltage calculation value is determined when the model parameters of the equivalent circuit model meet the query conditions; the model parameters include the estimated terminal voltage value, the estimated impedance value, and the estimated open-circuit voltage, and the query conditions include: the difference between the estimated terminal voltage value and the detection terminal voltage value is within the preset deviation range; the estimated impedance value is within the offline impedance range; and the estimated open-circuit voltage is within the normal open-circuit voltage value range.

[0128] In other words, to determine whether the model parameters are valid, consider the following: 1. Whether the difference between the estimated terminal voltage and the detected terminal voltage of the battery cell is within a preset deviation range, such as a tolerable value range; 2. Whether the estimated impedance parameter is within the offline reference parameter range; 3. The validity of the estimated open-circuit voltage (not an outlier and consistent with physical behavior). If the model parameters meet the above query conditions, the current estimated parameters are valid, and a table lookup can then be performed. Generally, during discharge, the estimated open-circuit voltage should be greater than the detected terminal voltage, and during charging, the estimated terminal voltage should be less than the detected terminal voltage.

[0129] Specifically, the impedance of the RC equivalent circuit model and the calculated value of the second open-circuit voltage are obtained. The determination is made by referring to the offline measured impedance parameters of the battery cell and the actual voltage range of the battery cell. If the calculated value of the second open-circuit voltage is within the offline reference parameters, that is, within the normal range, the current parameter is considered valid; otherwise, the valid parameter value of the previous moment is inherited.

[0130] Taking the configuration of three preset operating conditions—static discharge condition, constant rate discharge condition, and dynamic change condition—as an example, the static discharge condition corresponds to the first SOC calibration strategy, the constant rate discharge condition corresponds to the second SOC calibration strategy, and the dynamic change condition corresponds to the third SOC calibration strategy. See below for reference. Figure 4 An example of the SOC calibration method in this embodiment of the invention is illustrated below.

[0131] Step S8: Obtain the current current value, voltage value, temperature value, contactor switch status, and contactor disconnection cumulative time status information of the battery cell.

[0132] Step S9: Determine whether the first SOC calibration strategy is met based on the contactor switch status and the cumulative contactor disconnection time information. If yes, proceed to step S10; otherwise, proceed to step S11.

[0133] Step S10: Calibrate the current SOC value of the battery cell using the first SOC calibration strategy.

[0134] Step S11: Determine whether the current, voltage, and temperature values ​​of the battery cell meet the second SOC calibration strategy. If yes, proceed to step S12; otherwise, proceed to step S13.

[0135] Step S12: Calibrate the current SOC value of the battery cell using the second SOC calibration strategy.

[0136] Step S13: The current current value, voltage value and temperature value of the battery cell meet the third calibration strategy. The current SOC value of the battery cell is calibrated according to the third SOC calibration strategy by using the equivalent circuit model and parameter identification method.

[0137] For example, this invention can solve the problem of SOC calibration failure during the plateau interval of lithium iron manganese phosphate batteries under a single dual-voltage plateau interval calibration strategy or constant current discharge conditions.

[0138] To achieve the above objectives, this invention provides a SOC calibration method for dual-voltage plateau identification of lithium iron manganese phosphate battery cells, comprising: determining whether the current battery cell is in a voltage plateau interval period based on the current current value, voltage value, temperature value, contactor status, and contactor open cumulative time status parameter information of the battery pack; and calibrating the current SOC value of the battery pack in the following three ways: Method 1: when the current contactor switch status of the battery pack is open or a transition state from open to closed, determining whether the current battery cell voltage information is within the battery cell voltage plateau interval period and whether the battery pack contactor open cumulative time meets the resting correction time requirement; if so, calibrating the true SOC value of the current battery pack; Method 2: ... Formula 2: If the current battery state information of the battery cell meets the constant rate discharge requirement and is within the battery cell voltage plateau interval, then based on the current battery cell terminal current value, voltage value, temperature value and preset mapping table, the internal resistance information of the current battery cell is obtained, and the estimated value of the open circuit voltage of the current battery cell is calculated. Finally, based on this estimated value of the open circuit voltage and the OCV-SOC curve, the true estimated value of the SOC of the current battery pack is obtained by looking up the table and calibrating. Formula 3: If the current value, voltage value and temperature value of the current battery cell meet the dynamic change conditions, then based on the equivalent circuit model established by the current battery cell and combined with filtering methods, the true estimated value of the current battery SOC is estimated, and the battery pack SOC of the current voltage plateau interval is calibrated.

[0139] The main advantage of this method is that it can calibrate the true SOC value of battery cells under constant rate discharge or small-range current fluctuation discharge conditions during the battery voltage plateau interval, based on traditional static parameter calibration methods, dynamic parameter calibration single methods or combined methods. It effectively solves the problem that the SOC under constant rate discharge conditions during the voltage plateau interval cannot be calibrated by traditional calibration strategies, further improving the accuracy of the true SOC estimate of the battery pack. At the same time, it improves the situation where conventional single or combined correction methods have strict requirements for correction conditions or the algorithm cannot be involved in the actual voltage plateau interval, and avoids the problem of excessive cumulative error or even SOC jump caused by long-term ampere-hour method SOC estimation.

[0140] This method differs from existing SOC calibration methods for battery cells with multiple voltage plateaus or long voltage plateau periods in that it adds a new SOC calibration method for constant rate discharge or small-range current fluctuation discharge conditions during the voltage plateau interval, while employing static calibration and dynamic parameter calibration methods. Specifically, when it is determined that the current battery cell is in the voltage plateau interval, the SOC value of the current battery cell is estimated based on the current current value, voltage value, temperature value and preset mapping table lookup parameters, and then calibrated to the true SOC value of the current battery pack. A second aspect of the present invention provides an electronic device, such as... Figure 5 As shown, the electronic device 100 includes at least one processor 101 and a memory 102.

[0141] In this device, at least one processor 101 is communicatively connected to a memory 102, which stores a computer program that can be executed by the at least one processor 101. When the at least one processor 101 executes the computer program, it implements a SOC calibration method. The electronic device 100 can be a battery management system.

[0142] According to the electronic device of the present invention, a corresponding SOC calibration program can be stored in the memory. When implementing the SOC calibration method, the processor runs the program in the memory, obtains the circuit state information of the charging and discharging circuit where the battery cell is located, determines the target SOC calibration strategy, and after the battery state information of the battery cell meets the calibration conditions of the target SOC calibration strategy, the SOC value of the battery cell is calibrated by the corresponding SOC calibration strategy.

[0143] A third aspect of the present invention provides a non-volatile readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed, implements a SOC calibration method.

[0144] A fourth aspect of the present invention provides a vehicle, such as Figure 6 As shown, the vehicle 200 includes a battery unit 201 and an electronic device 100.

[0145] The electronic device 100 is used to perform SOC calibration on the battery cell 201.

[0146] According to the vehicle of the present invention, the electronic device obtains the loop state information of the charging and discharging circuit where the battery cell is located, determines the target SOC calibration strategy through the loop state information, and calibrates the SOC value of the battery cell through the corresponding SOC calibration strategy after the battery state information of the battery cell meets the calibration conditions of the target SOC calibration strategy. This can calibrate the SOC value of the battery cell during the dual voltage plateau interval, improve the accuracy of the battery cell SOC value, solve the problem that SOC calibration of the battery cell cannot be intervened during the dual voltage plateau interval, and avoid the problem of excessive cumulative error or even SOC value jump caused by the long-term inaccurate calibration of the SOC value.

[0147] In the description of this specification, any process or method described in the flowcharts or otherwise herein may be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order according to the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0148] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0149] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0150] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0151] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0152] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0153] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, substrate, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0154] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A SOC calibration method, characterized in that, include: Obtain the status parameter information of the charging and discharging circuit where the battery cell is located; Based on the state parameter information, the target operating conditions that the battery cell must satisfy are determined from at least two preset operating conditions, wherein each preset operating condition corresponds to a preset calibration strategy. Based on the target calibration strategy corresponding to the target operating conditions, a SOC calibration value is determined for performing SOC calibration of the battery cell.

2. The SOC calibration method according to claim 1, characterized in that, The status parameter information includes at least one of contactor status information and battery status information.

3. The SOC calibration method according to claim 2, characterized in that, The contactor status information includes at least one of the contactor switch status and the cumulative disconnection time of the contactor.

4. The SOC calibration method according to claim 3, characterized in that, The battery status information includes at least one of the following: terminal voltage, open circuit voltage, current, state of charge (SOC), and temperature of the battery cell.

5. The SOC calibration method according to claim 4, characterized in that, Based on the state parameter information, the target operating conditions that the battery cell must satisfy are determined from at least two preset operating conditions, including: The change in current of the battery cell within a first time threshold is obtained based on the current value. When the contactor switch is in the engaged state, the current change of the battery cell within a first time threshold is less than or equal to a first current change threshold, and the terminal voltage of the battery cell is within the target voltage range, the target operating condition satisfied by the battery cell is determined to be a constant rate discharge operating condition.

6. The SOC calibration method according to claim 4, characterized in that, Based on the state parameter information, the target operating conditions that the battery cell must satisfy are determined from at least two preset operating conditions, including: The current change of the battery cell within a first time threshold is obtained based on the current value, and the slope of the terminal voltage change is obtained based on the terminal voltage value. When the contactor switch is in the engaged state, the current change of the battery cell within the first time threshold is less than or equal to the first current change threshold, and the slope of the terminal voltage change is not less than the minimum value of the slope of the SOC-OCV relationship curve within the target voltage range, the target operating condition satisfied by the battery cell is determined to be the constant rate discharge operating condition.

7. The SOC calibration method according to claim 4, characterized in that, Based on the state parameter information, the target operating conditions that the battery cell must satisfy are determined from at least two preset operating conditions, including: When the contactor switch is in the first transition state and the cumulative disconnection time of the contactor is less than the target resting time, the target operating condition satisfied by the battery cell is determined to be the constant rate discharge operating condition, wherein the first transition state is the state of switching from disconnection to engagement.

8. The SOC calibration method according to any one of claims 5-7, characterized in that, The step of determining the SOC calibration value according to the target calibration strategy corresponding to the target operating conditions includes: Under the constant rate discharge condition, the first open-circuit voltage of the battery cell is calculated based on the battery state information of the battery cell. The SOC calibration value is determined based on the calculated value of the first open-circuit voltage and the first preset correspondence.

9. The SOC calibration method according to claim 8, characterized in that, The first open-circuit voltage of the battery cell is calculated based on the battery status information, including: Obtain the rate current parameter and internal resistance parameter of the battery cell; The first open-circuit voltage is calculated based on the terminal voltage value, the multiplier current parameter, and the internal resistance parameter.

10. The SOC calibration method according to claim 9, characterized in that, The first open-circuit voltage is calculated based on the terminal voltage value, the multiplier current parameter, and the internal resistance parameter, including: The internal resistance voltage value is obtained based on the current multiplier parameter and the internal resistance parameter; The first open-circuit voltage is calculated based on the terminal voltage value and the internal resistance voltage value.

11. The SOC calibration method according to claim 9, characterized in that, The process of obtaining the rate current parameter of the battery cell includes: The rate parameter of the battery cell is obtained based on the current value of the battery cell; The multiplier current parameter is obtained based on the multiplier parameter.

12. The SOC calibration method according to claim 9, characterized in that, The step of obtaining the internal resistance parameter of the battery cell includes: The internal resistance parameter is obtained based on the rate current parameter, the temperature value of the battery cell, and the SOC value of the battery cell.

13. The SOC calibration method according to claim 9, characterized in that, Obtaining the internal resistance parameters of the battery cell includes: The internal resistance parameter is obtained based on the current value of the battery cell and the corresponding terminal voltage value.

14. The SOC calibration method according to claim 4, characterized in that, Based on the state parameter information, the target operating conditions that the battery cell must satisfy are determined from at least two preset operating conditions, including: When the contactor switch is in the open state and the open-circuit voltage of the battery cell is within the target voltage range, the target operating condition satisfied by the battery cell is determined to be the static discharge operating condition.

15. The SOC calibration method according to claim 4, characterized in that, Based on the state parameter information, the target operating conditions that the battery cell must satisfy are determined from at least two preset operating conditions, including: When the contactor switch is in the first transition state, and the cumulative disconnection time of the contactor is greater than or equal to the target resting time corresponding to the temperature value of the battery cell, the target operating condition satisfied by the battery cell is determined to be the resting discharge operating condition, wherein the first transition state is the state of switching from disconnection to engagement.

16. The SOC calibration method according to claim 14 or 15, characterized in that, The step of determining the SOC calibration value according to the target calibration strategy corresponding to the target operating conditions includes: Under the static discharge condition, the SOC calibration value is determined based on the open-circuit voltage value of the battery cell and a second preset correspondence.

17. The SOC calibration method according to claim 4, characterized in that, Based on the state parameter information, the target operating conditions that the battery cell must satisfy are determined from at least two preset operating conditions, including: When the contactor status information is in the engaged state, the open-circuit voltage of the battery cell is within the target voltage range, and the current values ​​of two adjacent motion steps are different, the target operating condition satisfied by the battery cell is determined to be a dynamically changing operating condition.

18. The SOC calibration method according to claim 4, characterized in that, Based on the state parameter information, the target operating conditions that the battery cell must satisfy are determined from at least two preset operating conditions, including: The change in current of the battery cell within a second time threshold is obtained based on the current value of the battery cell. When the contactor switch is in the engaged state, the open-circuit voltage of the battery cell is within the target voltage range, and the current change of the battery cell within the second time threshold is greater than the second current change threshold, the target operating condition satisfied by the battery cell is determined to be a dynamically changing operating condition.

19. The SOC calibration method according to claim 17 or 18, characterized in that, The step of determining the SOC calibration value according to the target calibration strategy corresponding to the target operating conditions includes: Under the aforementioned dynamic operating conditions, the second open-circuit voltage of the battery cell is calculated based on the battery state information and equivalent circuit model of the battery cell. The SOC calibration value is determined based on the calculated value of the second open-circuit voltage and the third preset correspondence.

20. The SOC calibration method according to claim 19, characterized in that, The step of obtaining the calculated value of the second open-circuit voltage of the battery cell based on the battery state information and equivalent circuit model of the battery cell includes: The estimated terminal voltage, estimated impedance, and estimated open-circuit voltage are obtained based on the terminal voltage, current, and equivalent circuit model of the battery cell. When the difference between the estimated terminal voltage value and the detection terminal voltage value is within a preset deviation range, the estimated impedance value is within the offline impedance range, and the estimated open circuit voltage value is within the normal open circuit voltage value range, the estimated open circuit voltage value is used as the calculated value of the second open circuit voltage.

21. The SOC calibration method according to any one of claims 5, 6, 14, 17 and 18, characterized in that, The SOC-OCV relationship curve of the battery cell has a first voltage plateau period, a second voltage plateau period, and a dual voltage plateau interval period. The dual voltage plateau interval period is the curve interval from the end of the first voltage plateau period to the beginning of the second voltage plateau period. The target voltage range is the voltage interval between the lower limit of the first voltage plateau period and the upper limit of the second voltage plateau period.

22. An electronic device, characterized in that, include: At least one processor; A memory that is communicatively connected to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, which, when executing the computer program, implements the SOC calibration method according to any one of claims 1-21.

23. A non-volatile readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed, it implements the SOC calibration method according to any one of claims 1-21.

24. A vehicle, characterized in that, It includes a battery cell and the electronic device of claim 22, the electronic device being used to perform SOC calibration on the battery cell.

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