Method for correcting soc of lithium iron phosphate battery during charging process and storage medium

Abstract

This invention provides a method and storage medium for correcting the State of Charge (SOC) of a lithium iron phosphate (LFP) battery during charging, belonging to the field of LFP battery charging SOC technology. The correction method includes determining whether the LFP battery is in a 0.1C charging stage; and, if the LFP battery is in a 0.1C charging stage, obtaining the set of highest single-cell voltages within each 1% SOC interval. This invention determines whether the LFP battery is in a 0.1C charging state. If the LFP battery is in this state, it captures the highest single-cell voltage value within each 1% SOC interval, forming a set of highest single-cell voltages. Based on this set of highest single-cell voltages, dynamic correction is performed during subsequent charging. If the LFP battery is not in the charging stage, ampere-hour integration is used to calculate the LFP battery SOC, improving the accuracy and precision of LFP battery SOC calculation while also meeting customer experience requirements.

Description

Technical Field

[0001] This invention relates to the field of lithium iron phosphate battery charging SOC technology, specifically to a method for correcting the SOC of a lithium iron phosphate battery during charging and a storage medium therein. Background Technology

[0002] As electric vehicle sales gradually increase, their driving range is attracting more and more attention. The state-of-charge (SOC) of a lithium battery is a key parameter in determining the driving range of an electric vehicle.

[0003] Currently, the State of Charge (SOC) of lithium iron phosphate (LFP) batteries is mainly estimated using a combination of the ampere-hour (AH) integral method and the open-circuit voltage method. The AH integral method calculates the charge based on the cumulative charge and discharge current, requiring high current sampling accuracy. The open-circuit voltage method estimates the SOC based on the linear range at the discharge end of the battery's OCV-SOC curve after the battery has been idle for a sufficiently long time. The AH integral method is used to calculate the SOC during charging and discharging, while the open-circuit voltage method is used for SOC estimation and calibration when the battery is idle at the end of discharge. However, because LFP batteries have a relatively long voltage plateau range, the open-circuit voltage method cannot be used to estimate the SOC above 20%. If the vehicle operates within this voltage plateau range for an extended period, the accumulated error in the SOC will increase, negatively impacting the driving experience.

[0004] In the process of realizing this invention, the inventors of this application discovered that the above-mentioned solutions of the prior art have the drawback that when the vehicle operates in the voltage plateau range for a long time, the cumulative error of SOC becomes larger and larger. Summary of the Invention

[0005] The purpose of this invention is to provide a method and storage medium for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging. This method and storage medium have the function of dynamically correcting the SOC of the lithium iron phosphate battery in real time during charging.

[0006] To achieve the above objectives, embodiments of the present invention provide a method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging, comprising: Determine whether the lithium iron phosphate battery is in the 0.1C charging stage; When the lithium iron phosphate battery is determined to be in the 0.1C charging stage, the set of highest single-cell voltages within each 1% SOC interval is obtained; The SOC of the lithium iron phosphate battery is calibrated and corrected based on the set of highest single-cell voltages; If it is determined that the lithium iron phosphate battery is not in the 0.1C charging stage, the SOC of the lithium iron phosphate battery is calculated using ampere-hour integration.

[0007] Optionally, when determining that the lithium iron phosphate battery is in the 0.1C charging stage, obtaining the set of highest single-cell voltages within each 1% SOC interval includes: The initial record point value is set to zero. Record the highest single-cell voltage of the lithium iron phosphate battery within the current 1% SOC range, and obtain the updated value of the recorded point according to formula (1). (1) in, For the updated record point value, The value of the current record point; Determine whether the updated record point value is greater than or equal to the preset value; If the value of the updated recorded point is greater than or equal to a preset value, the multiple highest individual voltages are summarized to form a set of highest individual voltages. The SOC of the lithium iron phosphate battery is calibrated and corrected based on the set of highest single-cell voltages; If the value of the updated recording point is less than the preset value, the highest single cell voltage of the lithium iron phosphate battery in the current 1% SOC range is returned, and the value of the updated recording point is obtained according to formula (1).

[0008] Optionally, calibrating and correcting the SOC of the lithium iron phosphate battery based on the set of highest single-cell voltages includes: The difference in the highest single-cell voltage of the lithium iron phosphate battery at every 2% SOC is calculated according to formula (2). (2) in, This represents the difference in the highest single-cell voltage change of the lithium iron phosphate battery at every 2% SOC. The highest single-unit voltage set is the first The highest single-cell voltage, The number is an integer, and , The number of highest-voltage cells in the set of highest-voltage cells; The difference in SOC of the lithium iron phosphate battery at every 2% change is calculated according to formula (3). (3) in, This represents the difference in SOC (State of Charge) of the lithium iron phosphate battery at 2% intervals. The first in the set of lithium iron phosphate battery SOCs One SOC sequence; The voltage change rate of the lithium iron phosphate battery at every 2% SOC is calculated according to formula (4). (4) in, The voltage change rate of the lithium iron phosphate battery every 2% SOC; The voltage change rate of the lithium iron phosphate battery at every 2% SOC is summarized to form a voltage change rate set; The sequence of voltage change rates of the lithium iron phosphate battery at 2% SOC is calculated according to formula (5). (5) in, This is a sequence of voltage change rates for the lithium iron phosphate battery at 2% SOC intervals. The first in the set of voltage change rates Voltage change rate, The number is an integer, and ; The sequence of voltage change rates of the lithium iron phosphate batteries at every 2% SOC is compiled to form a sequence set.

[0009] Optionally, calibrating and correcting the SOC of the lithium iron phosphate battery based on the set of highest single-cell voltages further includes: Determine whether the last three sequences in the sequence set are less than 0, whether the fourth-to-last sequence in the sequence set is greater than or equal to 0, whether the fifth, sixth, and seventh-to-last sequences in the sequence set are greater than 0, and whether the fourth-to-last voltage change rate in the voltage change rate set is greater than or equal to 0.003; If the last three sequences in the sequence set are less than 0, the fourth-to-last sequence in the sequence set is greater than or equal to 0, the fifth, sixth, and seventh-to-last sequences in the sequence set are greater than 0, and the fourth-to-last voltage change rate in the voltage change rate set is greater than or equal to 0.003, then the lithium iron phosphate battery SOC set will be... Each SOC sequence is used as an inflection point, and the corresponding true SOC value is recorded as a correction value.

[0010] Optionally, calibrating and correcting the SOC of the lithium iron phosphate battery based on the set of highest single-cell voltages further includes: Determine whether the second-to-last and third-to-last sequences in the sequence set are less than 0, whether the fourth-to-last sequence in the sequence set is greater than or equal to 0, whether the fifth-to-last, sixth-to-last, and seventh-to-last sequences in the sequence set are greater than 0, and whether the fourth voltage change rate in the voltage change rate set is greater than or equal to 0.004; If the second-to-last and third-to-last sequences in the sequence set are less than 0, the fourth-to-last sequence in the sequence set is greater than or equal to 0, the fifth-to-last, sixth-to-last, and seventh-to-last sequences in the sequence set are greater than 0, and the fourth-to-last voltage change rate in the voltage change rate set is greater than or equal to 0.004, then the sequence in the lithium iron phosphate battery SOC set is... Each SOC sequence is used as an inflection point, and the corresponding true SOC value is recorded as a correction value.

[0011] Optionally, calibrating and correcting the SOC of the lithium iron phosphate battery based on the set of highest single-cell voltages further includes: Determine whether the last three sequences in the sequence set are less than 0, whether the fourth to seventh sequences from the end of the sequence set are greater than or equal to 0, whether two consecutive sequences from the fourth to seventh sequences from the end of the sequence set are greater than 0, and whether the fourth voltage change rate in the voltage change rate set is greater than or equal to 0.004; If, in the case that the last three sequences in the sequence set are less than 0, the fourth to seventh sequences from the end of the sequence set are greater than or equal to 0, and there are two consecutive sequences greater than 0 in the fourth to seventh sequences from the end of the sequence set, and the fourth voltage change rate in the voltage change rate set is greater than or equal to 0.004, then the lithium iron phosphate battery SOC set will be... Each SOC sequence is used as an inflection point, and the corresponding true SOC value is recorded as a correction value.

[0012] Optionally, calibrating and correcting the SOC of the lithium iron phosphate battery based on the set of highest single-cell voltages further includes: The first correction parameter of the SOC sequence of the lithium iron phosphate battery is calculated according to formula (6). (6) in, This is the first correction parameter for the SOC sequence of the lithium iron phosphate battery. The first in the set of lithium iron phosphate battery SOCs One SOC sequence; Determine the highest single-unit voltage set of the highest single-unit voltage set. Whether the highest single-cell voltage is less than 3.34V and whether the first correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%; In determining the set of highest single-unit voltages, the first... If the highest single-cell voltage is less than 3.34V and the first correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%, then 17% will be used as the correction value.

[0013] Optionally, calibrating and correcting the SOC of the lithium iron phosphate battery based on the set of highest single-cell voltages further includes: The second correction parameter of the SOC sequence of the lithium iron phosphate battery is calculated according to formula (7). (7) in, This is the second correction parameter for the SOC sequence of the lithium iron phosphate battery; Determine the highest single-unit voltage set of the highest single-unit voltage set. Whether the highest single-cell voltage is greater than 3.34V and whether the second correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%; In determining the set of highest single-unit voltages, the first... If the highest single-cell voltage is greater than 3.34V and the second correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%, then 63% will be used as the correction value.

[0014] Optionally, calibrating and correcting the SOC of the lithium iron phosphate battery based on the set of highest single-cell voltages further includes: Determine the first [number] in the set of lithium iron phosphate battery SOCs. Whether the SOC sequence is greater than the correction value; In determining the SOC set of the lithium iron phosphate battery, the first... If the SOC sequence is greater than the correction value, the SOC of the lithium iron phosphate battery is calibrated by charging deceleration. In determining the SOC set of the lithium iron phosphate battery, the first... If the SOC sequence is less than the correction value, the SOC of the lithium iron phosphate battery is calibrated for accelerated charging.

[0015] On the other hand, the present invention provides a computer-readable storage medium storing instructions for being read by a machine to cause the machine to perform any of the above-described correction methods.

[0016] Through the above technical solution, the method and storage medium for correcting the SOC of a lithium iron phosphate battery during charging provided by this invention determine whether the lithium iron phosphate battery is in a 0.1C charging state. If the lithium iron phosphate battery is in this state, the highest value of the single cell voltage at every 1% SOC interval is captured, i.e., the highest single cell voltage, and a set of highest single cell voltages is formed. Dynamic correction is performed in the subsequent charging process based on this set of highest single cell voltages. If the lithium iron phosphate battery is not in the charging stage, the SOC of the lithium iron phosphate battery is calculated using ampere-hour integration, which improves the accuracy and precision of the SOC calculation of the lithium iron phosphate battery, and also meets the customer's experience.

[0017] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of a method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating the process of obtaining the set of highest single-cell voltages in a method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging, according to an embodiment of the present invention. Figure 3 This is a flowchart of a method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging, according to an embodiment of the present invention, before calibration. Figure 4 This is a flowchart of a calibration judgment process in a method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging, according to an embodiment of the present invention. Figure 5 This is a flowchart of a calibration judgment process in a method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging, according to an embodiment of the present invention. Figure 6 This is a flowchart of a calibration judgment process in a method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging, according to an embodiment of the present invention. Figure 7 This is a flowchart of a calibration judgment process in a method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging, according to an embodiment of the present invention. Figure 8 This is a flowchart of a calibration judgment process in a method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging, according to an embodiment of the present invention. Figure 9 This is a flowchart illustrating the correction process for the SOC of a lithium iron phosphate battery during charging, according to an embodiment of the present invention. Figure 10 This is a method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging according to an embodiment of the present invention, showing the CCV curves of a lithium iron phosphate battery at 0.1C charging at different temperatures. Figure 11 This is an example diagram showing the voltage change rate of a lithium iron phosphate battery every 2% of its state of charge (SOC) during charging, according to an embodiment of the present invention. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0020] Figure 1 This is a flowchart of a method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging according to an embodiment of the present invention. Figure 1 In this context, the correction method may include: In step S10, it is determined whether the lithium iron phosphate battery is in the 0.1C charging stage. To improve the accuracy of the SOC calculation for the lithium iron phosphate battery, its state needs to be determined, categorized as charging or non-charging. Specifically, lithium iron phosphate batteries are generally slow-charged at a rate of 0.1C.

[0021] In step S11, when the lithium iron phosphate battery is determined to be in the 0.1C charging stage, the set of highest single-cell voltages within each 1% SOC interval is obtained. Specifically, if the lithium iron phosphate battery is in the 0.1C charging stage, the battery charging curve at 0.1C rate can be obtained, and the highest single-cell voltage within each interval is obtained at 1% SOC intervals. These multiple highest single-cell voltages are then summarized to obtain the set of highest single-cell voltages. Specifically, the 0.1C charging CCV curves of the lithium iron phosphate battery at different temperatures can be obtained as follows: Figure 4 As shown, specifically, during the 0.1C slow charging process of lithium iron phosphate batteries, there are two very distinct voltage plateau regions: the 25% to 55% SOC range and the 67% to 88% range. Before entering these two voltage plateau regions, the changes in single-cell voltage at equally spaced SOC intervals are very significant.

[0022] In step S12, the SOC of the lithium iron phosphate battery is calibrated and corrected based on the set of highest single-cell voltages. Specifically, after obtaining the set of highest single-cell voltages, a calculation and conversion are performed based on this set to calibrate and correct the SOC of the lithium iron phosphate battery.

[0023] In step S13, if it is determined that the lithium iron phosphate battery is not in the 0.1C charging stage, the SOC of the lithium iron phosphate battery is calculated using ampere-hour integration. Specifically, if the lithium iron phosphate battery is not in the 0.1C charging stage, it indicates that the lithium iron phosphate battery is in a static or discharging state, and in this case, the SOC of the lithium iron phosphate battery can be calculated and monitored using the ampere-hour integration method.

[0024] In steps S10 to S13, the state of the lithium iron phosphate battery is determined. If the lithium iron phosphate battery is in the 0.1C slow charging stage, the battery charging curve at the 0.1C rate is obtained, and the set of highest single-cell voltages within the corresponding intervals is obtained at 1% SOC intervals. Based on this set of highest single-cell voltages, a correction value related to the SOC of the lithium iron phosphate battery is calculated, and the SOC of the lithium iron phosphate battery is corrected according to this correction value. If the lithium iron phosphate battery is not in the 0.1C slow charging stage, it indicates that the lithium iron phosphate battery is in a static or discharging state. In this case, ampere-hour integration is used to calculate and monitor the SOC of the lithium iron phosphate battery.

[0025] Traditional methods for calculating and correcting the State of Charge (SOC) of lithium iron phosphate (LFP) batteries primarily employ a combination of the ampere-hour integration method and the open-circuit voltage method. However, due to the long voltage plateau range of LFP batteries, the open-circuit voltage method cannot be used to estimate the SOC above 20%. If a vehicle operates within this voltage plateau range for an extended period, the accumulated error in the SOC will increase, negatively impacting the driving experience. In this embodiment of the invention, the highest single-cell voltage at equal intervals is used as the current SOC correction value to dynamically adjust the battery charging process. This method reliably calibrates and corrects the SOC value even when the vehicle operates within the voltage plateau range for extended periods, leading to large SOC errors. This improves the accuracy and precision of LFP battery SOC calculations while also satisfying customer experience requirements.

[0026] In this embodiment of the invention, in order to obtain the set of highest single-cell voltages of lithium iron phosphate batteries, it is also necessary to obtain the highest single-cell voltage within equally spaced intervals of the battery charging curve under charging conditions. Specific steps can be as follows: Figure 2 As shown. Specifically, in Figure 2 In this context, the correction method may include: In step S20, the value of the initial recording point is obtained as zero. Specifically, an initial recording point is first defined, and its value is assigned to 0.

[0027] In step S21, the highest single-cell voltage of the lithium iron phosphate battery within the current 1% SOC range is recorded, and the updated value of the recorded point is obtained according to formula (1). (1) in, For the updated record point value, This is the value at the current recording point. Specifically, the highest single-cell voltage within each 1% SOC interval of the lithium iron phosphate battery charging curve is acquired, and the value at the current recording point is recorded synchronously after acquiring the highest single-cell voltage within each 1% SOC interval.

[0028] In step S22, it is determined whether the updated value of the recorded point is greater than or equal to a preset value. To ensure the accuracy of subsequent SOC correction, it is also necessary to determine the number of recorded points, i.e., the value of each recorded point.

[0029] In step S23, if the updated value of the recorded point is greater than or equal to a preset value, the multiple highest individual voltages are summarized to form a set of highest individual voltages. Specifically, if the updated value of the recorded point is greater than or equal to the preset value, it indicates that the number of highest individual voltages meets the requirement, and thus the highest individual voltage is summarized.

[0030] In step S24, the SOC of the lithium iron phosphate battery is calibrated and corrected based on the set of highest single-cell voltages. Specifically, after obtaining the set of highest single-cell voltages, the SOC of the lithium iron phosphate battery is dynamically corrected to ensure the accuracy of the SOC and avoid error accumulation.

[0031] In step S25, if the value of the updated recording point is less than the preset value, the highest single-cell voltage of the lithium iron phosphate battery within the current 1% SOC range is returned, and the updated recording point value is obtained according to formula (1). If the value of the updated recording point is less than the preset value, it means that the number of highest single-cell voltages captured is insufficient, and more data needs to be captured.

[0032] In steps S20 to S25, the initial value of the recording point is first defined as zero. Then, the highest single-cell voltage within each 1% SOC interval of the lithium iron phosphate battery is obtained, and the value of the recording point is updated synchronously. The value of the recording point is judged. If the value of the recording point is greater than or equal to a preset value, it means that there are enough highest single-cell voltages. The highest single-cell voltages are summarized to dynamically correct the SOC of the lithium iron phosphate battery. If the value of the recording point is less than the preset value, it is necessary to continue to capture the highest single-cell voltage of the next 1% SOC interval to ensure accurate correction of the battery SOC in the future.

[0033] In this embodiment of the invention, in order to reliably correct the SOC of the lithium iron phosphate battery, it is also necessary to calculate and determine the set of highest single-cell voltages. Specific steps can be as follows: Figures 3 to 9 As shown. Specifically, in Figures 3 to 9 In this context, the correction method may include: In step S30, the difference in the highest single-cell voltage change of the lithium iron phosphate battery at every 2% SOC is calculated according to formula (2). (2) in, This represents the difference in the highest single-cell voltage of a lithium iron phosphate battery at every 2% SOC. The highest single-unit voltage in the set The highest single-cell voltage, The number is an integer, and , This represents the number of highest-voltage cells in the set of highest-voltage cells. Specifically, the set of highest-voltage cells can be represented as... .

[0034] In step S31, the difference in SOC of the lithium iron phosphate battery at every 2% change is calculated according to formula (3). (3) in, This represents the difference in SOC (State of Charge) for lithium iron phosphate batteries at 2% intervals. The first in the set of lithium iron phosphate battery SOCs A set of SOC sequences. Specifically, the SOC set can be represented as... .

[0035] In step S32, the voltage change rate of the lithium iron phosphate battery at every 2% SOC is calculated according to formula (4). (4) in, This represents the voltage change rate of a lithium iron phosphate battery every 2% of its state of charge (SOC). Specifically, an example graph showing the voltage change rate of a lithium iron phosphate battery every 2% of its SOC can be found... Figure 5 As shown.

[0036] In step S33, the voltage change rate of the lithium iron phosphate battery at every 2% SOC is summarized to form a voltage change rate set. Specifically, the voltage change rate set can be represented as... .

[0037] In step S34, the sequence of voltage change rates of the lithium iron phosphate battery at every 2% SOC is calculated according to formula (5). (5) in, This is a sequence of voltage change rates for lithium iron phosphate batteries at 2% SOC. The first in the set of voltage change rates Voltage change rate, The number is an integer, and Specifically, the sequence of voltage change rate for lithium iron phosphate batteries at 2% SOC also represents the change in voltage change rate for lithium iron phosphate batteries at 2% SOC.

[0038] In step S35, the sequence of voltage change rates of the lithium iron phosphate battery at every 2% SOC is summarized to form a sequence set. Specifically, the sequence set can be represented as follows: .

[0039] In step S36, it is determined whether the last three sequences in the sequence set are less than 0, whether the fourth-to-last sequence in the sequence set is greater than or equal to 0, whether the fifth, sixth, and seventh-to-last sequences in the sequence set are greater than 0, and whether the fourth-to-last voltage change rate in the voltage change rate set is greater than or equal to 0.003.

[0040] In step S37, if the last three sequences in the sequence set are less than 0, the fourth-to-last sequence in the sequence set is greater than or equal to 0, and the fifth, sixth, and seventh-to-last sequences in the sequence set are greater than 0, and the fourth-to-last voltage change rate in the voltage change rate set is greater than or equal to 0.003, then the lithium iron phosphate battery SOC set is set to... Each SOC sequence is used as an inflection point, and the corresponding true SOC value is recorded as a correction value.

[0041] In step S38, it is determined whether the second to last and third to last sequences in the sequence set are less than 0, whether the fourth to last sequence in the sequence set is greater than or equal to 0, whether the fifth to last, sixth to last, and seventh to last sequences in the sequence set are greater than 0, and whether the fourth voltage change rate in the voltage change rate set is greater than or equal to 0.004.

[0042] In step S39, if the second-to-last and third-to-last sequences in the sequence set are less than 0, the fourth-to-last sequence in the sequence set is greater than or equal to 0, the fifth-to-last, sixth-to-last, and seventh-to-last sequences in the sequence set are greater than 0, and the fourth-to-last voltage change rate in the voltage change rate set is greater than or equal to 0.004, then the lithium iron phosphate battery SOC set is... Each SOC sequence is used as an inflection point, and the corresponding true SOC value is recorded as a correction value.

[0043] In step S40, it is determined whether the last three sequences in the sequence set are less than 0, whether the fourth to seventh sequences from the end of the sequence set are greater than or equal to 0, whether two consecutive sequences from the fourth to seventh sequences from the end of the sequence set are greater than 0, and whether the fourth voltage change rate in the voltage change rate set is greater than or equal to 0.004.

[0044] In step S41, if the last three sequences in the sequence set are less than 0, and the fourth to seventh sequences from the end of the sequence set are greater than or equal to 0, and there are two consecutive sequences greater than 0 in the fourth to seventh sequences from the end of the sequence set, and the fourth voltage change rate in the voltage change rate set is greater than or equal to 0.004, then the fourth sequence in the lithium iron phosphate battery SOC set is... Each SOC sequence is used as an inflection point, and the corresponding true SOC value is recorded as a correction value.

[0045] In step S42, the first correction parameter of the SOC sequence of the lithium iron phosphate battery is calculated according to formula (6). (6) in, The first correction parameter for the SOC sequence of lithium iron phosphate batteries. The first in the lithium iron phosphate battery SOC set A number of SOC sequences.

[0046] In step S43, determine the highest single-unit voltage set. Whether the highest single-cell voltage is less than 3.34V and whether the first correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%.

[0047] In step S44, the highest single-unit voltage set is determined as follows: If the highest single-cell voltage is less than 3.34V and the first correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%, then 17% will be used as the correction value.

[0048] In step S45, the second correction parameter of the SOC sequence of the lithium iron phosphate battery is calculated according to formula (7). (7) in, This is the second correction parameter for the SOC sequence of lithium iron phosphate batteries.

[0049] In step S46, determine the highest single-unit voltage set. Whether the highest single-cell voltage is greater than 3.34V and whether the second correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%.

[0050] In step S47, the highest single-unit voltage set is determined as follows: If the highest single-cell voltage is greater than 3.34V and the second correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%, then 63% will be used as the correction value.

[0051] In step S48, determine the first [number] battery in the lithium iron phosphate battery SOC set. Does each SOC sequence exceed the correction value?

[0052] In step S49, the first [cell octet] in the set of lithium iron phosphate battery SOCs is determined. When the SOC sequence is greater than the correction value, the SOC of the lithium iron phosphate battery is calibrated by charging deceleration.

[0053] In step S50, the first [cell octet] in the set of lithium iron phosphate battery SOCs is determined. When the SOC sequence is less than the correction value, the SOC of the lithium iron phosphate battery is calibrated for accelerated charging.

[0054] In steps S30 to S50, the highest single-cell voltage change difference and the change difference of the lithium iron phosphate battery at every 2% SOC are first calculated. Then, the voltage change rate of the lithium iron phosphate battery at every 2% SOC is calculated and a voltage change rate set is formed. Based on this voltage change rate set, a sequence of voltage change rates of the lithium iron phosphate battery at every 2% SOC is calculated and a sequence set is formed. Finally, the last to seventh-to-last sequences in the sequence set and the fourth-to-last voltage change rate in the voltage change rate set are judged. At the same time, the highest single-cell voltage set is also judged. The system determines the highest single-cell voltage, the first correction parameter, and the second correction parameter to obtain a correction value. Based on this correction value, the SOC of the lithium iron phosphate battery can be dynamically corrected to improve the accuracy and precision of the SOC, thereby meeting customer experience requirements.

[0055] On the other hand, the present invention also provides a computer-readable storage medium storing instructions for being read by a machine to cause the machine to perform any of the above-described correction methods.

[0056] Through the above technical solution, the method and storage medium for correcting the SOC of a lithium iron phosphate battery during charging provided by this invention determine whether the lithium iron phosphate battery is in a 0.1C charging state. If the lithium iron phosphate battery is in this state, the highest value of the single cell voltage at every 1% SOC interval is captured, i.e., the highest single cell voltage, and a set of highest single cell voltages is formed. Dynamic correction is performed in the subsequent charging process based on this set of highest single cell voltages. If the lithium iron phosphate battery is not in the charging stage, the SOC of the lithium iron phosphate battery is calculated using ampere-hour integration, which improves the accuracy and precision of the SOC calculation of the lithium iron phosphate battery, and also meets the customer's experience.

[0057] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0058] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0059] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0060] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0061] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0062] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0063] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0064] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0065] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for correcting the state of charge (SOC) of a lithium iron phosphate battery during charging, characterized in that, include: Determine whether the lithium iron phosphate battery is in the 0.1C charging stage; When the lithium iron phosphate battery is determined to be in the 0.1C charging stage, the set of highest single-cell voltages within each 1% SOC interval is obtained; The SOC of the lithium iron phosphate battery is calibrated and corrected based on the set of highest single-cell voltages; If it is determined that the lithium iron phosphate battery is not in the 0.1C charging stage, the SOC of the lithium iron phosphate battery is calculated by ampere-hour integration; The SOC calibration correction of the lithium iron phosphate battery based on the highest single-cell voltage set includes: The difference in the highest single-cell voltage of the lithium iron phosphate battery at every 2% SOC is calculated according to formula (2). ，（2） in, This represents the difference in the highest single-cell voltage change of the lithium iron phosphate battery at every 2% SOC. The highest single-unit voltage set is the first The highest single-cell voltage, The number is an integer, and , The number of highest-voltage cells in the set of highest-voltage cells; The difference in SOC of the lithium iron phosphate battery at every 2% change is calculated according to formula (3). ，（3） in, This represents the difference in SOC (State of Charge) of the lithium iron phosphate battery at 2% intervals. The first in the set of lithium iron phosphate battery SOCs One SOC sequence; The voltage change rate of the lithium iron phosphate battery at every 2% SOC is calculated according to formula (4). ，（4） in, The voltage change rate of the lithium iron phosphate battery every 2% SOC; The voltage change rate of the lithium iron phosphate battery at every 2% SOC is summarized to form a voltage change rate set; The sequence of voltage change rates of the lithium iron phosphate battery at 2% SOC is calculated according to formula (5). ，（5） in, This is a sequence of voltage change rates for the lithium iron phosphate battery at 2% SOC intervals. The first in the set of voltage change rates Voltage change rate, The number is an integer, and ; The sequence of voltage change rate at every 2% SOC of the lithium iron phosphate battery is compiled to form a sequence set; The calibration correction of the SOC of the lithium iron phosphate battery based on the highest single-cell voltage set also includes: Determine whether the last three sequences in the sequence set are less than 0, whether the fourth-to-last sequence in the sequence set is greater than or equal to 0, whether the fifth, sixth, and seventh-to-last sequences in the sequence set are greater than 0, and whether the fourth-to-last voltage change rate in the voltage change rate set is greater than or equal to 0.003; If the last three sequences in the sequence set are less than 0, the fourth-to-last sequence in the sequence set is greater than or equal to 0, the fifth, sixth, and seventh-to-last sequences in the sequence set are greater than 0, and the fourth-to-last voltage change rate in the voltage change rate set is greater than or equal to 0.003, then the lithium iron phosphate battery SOC set will be... Each SOC sequence is used as an inflection point, and the corresponding true SOC value is recorded as a correction value.

2. The correction method according to claim 1, characterized in that, When the lithium iron phosphate battery is determined to be in the 0.1C charging stage, the set of highest single-cell voltages within each 1% SOC interval includes: The initial record point value is set to zero. Record the highest single-cell voltage of the lithium iron phosphate battery within the current 1% SOC range, and obtain the updated value of the recorded point according to formula (1). ，（1） in, For the updated record point value, The value of the current record point; Determine whether the updated record point value is greater than or equal to the preset value; If the value of the updated recorded point is greater than or equal to a preset value, the multiple highest individual voltages are summarized to form a set of highest individual voltages. The SOC of the lithium iron phosphate battery is calibrated and corrected based on the set of highest single-cell voltages; If the value of the updated recording point is less than the preset value, the highest single cell voltage of the lithium iron phosphate battery in the current 1% SOC range is returned, and the value of the updated recording point is obtained according to formula (1).

3. The correction method according to claim 2, characterized in that, The calibration correction of the SOC of the lithium iron phosphate battery based on the highest single-cell voltage set also includes: Determine whether the second-to-last and third-to-last sequences in the sequence set are less than 0, whether the fourth-to-last sequence in the sequence set is greater than or equal to 0, whether the fifth-to-last, sixth-to-last, and seventh-to-last sequences in the sequence set are greater than 0, and whether the fourth voltage change rate in the voltage change rate set is greater than or equal to 0.004; If the second-to-last and third-to-last sequences in the sequence set are less than 0, the fourth-to-last sequence in the sequence set is greater than or equal to 0, the fifth-to-last, sixth-to-last, and seventh-to-last sequences in the sequence set are greater than 0, and the fourth-to-last voltage change rate in the voltage change rate set is greater than or equal to 0.004, then the sequence in the lithium iron phosphate battery SOC set is... Each SOC sequence is used as an inflection point, and the corresponding true SOC value is recorded as a correction value.

4. The correction method according to claim 3, characterized in that, The calibration correction of the SOC of the lithium iron phosphate battery based on the highest single-cell voltage set also includes: Determine whether the last three sequences in the sequence set are less than 0, whether the fourth to seventh sequences from the end of the sequence set are greater than or equal to 0, whether two consecutive sequences from the fourth to seventh sequences from the end of the sequence set are greater than 0, and whether the fourth voltage change rate in the voltage change rate set is greater than or equal to 0.004; If, in the case that the last three sequences in the sequence set are less than 0, the fourth to seventh sequences from the end of the sequence set are greater than or equal to 0, and there are two consecutive sequences greater than 0 in the fourth to seventh sequences from the end of the sequence set, and the fourth voltage change rate in the voltage change rate set is greater than or equal to 0.004, then the lithium iron phosphate battery SOC set will be... Each SOC sequence is used as an inflection point, and the corresponding true SOC value is recorded as a correction value.

5. The correction method according to claim 4, characterized in that, The calibration correction of the SOC of the lithium iron phosphate battery based on the highest single-cell voltage set also includes: The first correction parameter of the SOC sequence of the lithium iron phosphate battery is calculated according to formula (6). ，（6） in, This is the first correction parameter for the SOC sequence of the lithium iron phosphate battery. The first in the set of lithium iron phosphate battery SOCs One SOC sequence; Determine the highest single-unit voltage set of the highest single-unit voltage set. Whether the highest single-cell voltage is less than 3.34V and whether the first correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%; In determining the set of highest single-unit voltages, the first... If the highest single-cell voltage is less than 3.34V and the first correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%, then 17% will be used as the correction value.

6. The correction method according to claim 5, characterized in that, The calibration correction of the SOC of the lithium iron phosphate battery based on the highest single-cell voltage set also includes: The second correction parameter of the SOC sequence of the lithium iron phosphate battery is calculated according to formula (7). ，（7） in, This is the second correction parameter for the SOC sequence of the lithium iron phosphate battery; Determine the highest single-unit voltage set of the highest single-unit voltage set. Whether the highest single-cell voltage is greater than 3.34V and whether the second correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%; In determining the set of highest single-unit voltages, the first... If the highest single-cell voltage is greater than 3.34V and the second correction parameter of the SOC sequence of the lithium iron phosphate battery is less than 20%, then 63% will be used as the correction value.

7. The correction method according to claim 6, characterized in that, The calibration correction of the SOC of the lithium iron phosphate battery based on the highest single-cell voltage set also includes: Determine the first [number] in the set of lithium iron phosphate battery SOCs. Whether the SOC sequence is greater than the correction value; In determining the SOC set of the lithium iron phosphate battery, the first... If the SOC sequence is greater than the correction value, the SOC of the lithium iron phosphate battery is calibrated by charging deceleration. In determining the SOC set of the lithium iron phosphate battery, the first... If the SOC sequence is less than the correction value, the SOC of the lithium iron phosphate battery is calibrated for accelerated charging.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores instructions that are read by a machine to cause the machine to perform the correction method as described in any one of claims 1 to 7.

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