Lithium iron phosphate battery SOC full charge correction method, apparatus and device, and vehicle
By judging the actual charging current of the battery during the charging process of lithium iron phosphate batteries, avoiding SOC error correction caused by abnormal output of large current on the charging pile, the problem of inflated battery capacity and mileage is solved.
Patent Information
- Application Number
- CN202510358798.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-25
- Publication Date
- 2025-05-30
AI Technical Summary
Due to the abnormal output of large current from the charging pile, the single voltage of the lithium iron phosphate battery rapidly increased during the charging process, and the SOC was wrongly corrected, resulting in the inflated battery capacity and inflated mileage.
During the charging process of lithium iron phosphate battery, if the battery's single voltage reaches the preset full charge condition, the full charge flag position is set, and whether to fully charge correction is made for the SOC based on the actual charging current before the full charge flag position is set.
By determining whether the actual charging current of the battery is less than the preset current, avoid SOC error correction caused by the abnormal output of large current of the charging pile, and reduce the inflated battery power and mileage.
Smart Images
Figure CN120065007A_ABST
Abstract
Description
Technical Field
[0001] The present invention is used in the field of new energy vehicles. Specifically, it is a method, device, equipment and vehicle for correcting the full charge of the state of charge (SOC) of a lithium iron phosphate battery. Background Art
[0002] Due to the long plateau region of the voltage of the lithium iron phosphate battery, the SOC estimation mainly relies on the ampere-hour integration of the current collected by the current sensor. If the sampling accuracy of the current sensor is poor and the vehicle is in a shallow charge and discharge state for a long time (the battery is not fully charged or discharged regularly), problems such as large SOC estimation deviation, SOC jump, and power interruption will occur. Generally, an SOC correction strategy is set to improve the SOC estimation accuracy, thereby reducing the probability of the above problems.
[0003] Due to the limitation of the plateau region of the lithium iron phosphate battery, the current SOC correction for the lithium iron phosphate battery focuses on the end of the SOC, such as full discharge correction and full charge correction. During the full charge correction, during the charging process, the SOC is corrected to 100% by judging whether the single cell voltage is greater than the full charge threshold for a certain period of time, thereby eliminating the SOC estimation deviation.
[0004] The problem of the prior art is that during the charging process, some charging piles will abnormally output a large current. After the large current flows into the battery pack, the single cell voltage will be quickly pulled up to the full charge threshold, resulting in the SOC being wrongly corrected to 100%, the battery stops charging due to full charge, and further resulting in a falsely high SOC and a falsely high mileage. Summary of the Invention
[0005] The present invention provides a method for correcting the full charge of the SOC of a lithium iron phosphate battery, which is used to solve the problem that the SOC is wrongly corrected to 100% when the battery is not fully charged due to the abnormal output of a large current by the charging pile.
[0006] The technical solution of the present invention is as follows:
[0007] On the one hand, the present invention provides a method for correcting the full charge of the SOC of a lithium iron phosphate battery, including:
[0008] During the charging process of the lithium iron phosphate battery, if it is recognized that the single cell voltage of the battery reaches the preset full charge condition, set the full charge flag bit;
[0009] After the full charge flag bit is set, select whether to perform full charge correction on the SOC according to the actual charging current of the battery before the full charge flag bit is set.
[0010] Further, the single cell voltage of the battery reaching the preset full charge condition is:
[0011] The highest single cell voltage of the battery is greater than or equal to the preset full charge threshold and lasts for the first preset duration.
[0012] Further, the steps of selecting to perform full charge correction on the SOC or exiting the charging according to the actual charging current of the battery before the full charge flag is set include:
[0013] Obtain the actual charging current of the battery within a preset time period before the full charge flag is set;
[0014] Before the full charge flag is set, if the actual charging current of the battery is less than the preset current and remains for a second preset duration, perform full charge correction on the SOC; otherwise, do not perform full charge correction on the SOC.
[0015] Further, the preset current is equal to the sum of a preset product and a pre-calibrated redundant current threshold, and the preset product is equal to the product of the rated capacity of the battery cell and the maximum demand current of the battery during full charge.
[0016] Further, the maximum demand current of the battery during full charge is determined by looking up a table.
[0017] Further, the method further includes:
[0018] If full charge correction is performed on the SOC, output a prompt indicating that the charging is completed and end the charging;
[0019] If full charge correction is not performed on the SOC, output an abnormal prompt indicating that the charging is exited due to the charging current exceeding the limit and end the charging.
[0020] On the other hand, the present invention provides a device for full charge correction of the SOC of a lithium iron phosphate battery, including:
[0021] A setting module, configured to set the full charge flag when it is recognized that the single cell voltage of the battery reaches the preset full charge condition during the charging process of the lithium iron phosphate battery;
[0022] A correction module, configured to select to perform full charge correction on the SOC or not perform full charge correction according to the actual charging current of the battery before the full charge flag is set after the full charge flag is set.
[0023] Further, the single cell voltage of the battery reaching the preset full charge condition is:
[0024] The highest single cell voltage of the battery is greater than or equal to the preset full charge threshold and lasts for a first preset duration.
[0025] Further, the correction module includes:
[0026] A charging current acquisition unit, configured to obtain the actual charging current of the battery within a preset time period before the full charge flag is set;
[0027] A correction unit is configured to perform full charge correction on the SOC if the actual charging current of the battery is less than a preset current and maintains for a second preset duration before the full charge flag bit is set; otherwise, no full charge correction is performed on the SOC.
[0028] On the other hand, the present application also provides a control device, including a processor, a memory, and a program or instruction stored on the memory and executable on the processor. When the program or instruction is executed by the processor, the steps of the full charge correction of the SOC of the lithium iron phosphate battery as described above are implemented.
[0029] On the other hand, the present application also provides a vehicle, including the full charge correction device of the SOC of the lithium iron phosphate battery as described above.
[0030] The beneficial effects of the present invention are:
[0031] During the charging process, if the highest single cell voltage of the battery exceeds the preset full charge threshold, the full charge correction of the SOC is not directly performed. Instead, it is further determined whether the actual charging current of the battery is less than the preset current, excluding the situation where the highest single cell voltage of the battery changes to exceed the preset full charge threshold due to abnormal output of a large current by the charging pile but the battery power is actually not fully charged, and avoiding the situation where the SOC is mis-corrected for full charge, resulting in a falsely high battery power. Description of the Drawings
[0032] Figure 1 It is a flowchart of the method for full charge correction of the SOC of the lithium iron phosphate battery in the embodiment of the present application;
[0033] Figure 2 It is a detailed flowchart of the method for full charge correction of the SOC of the lithium iron phosphate battery in the embodiment of the present application;
[0034] Figure 3 It is a flowchart of the full charge correction device of the SOC of the lithium iron phosphate battery in the embodiment of the present application. Detailed Embodiments
[0035] For the convenience of understanding by those skilled in the art, the present invention patent will be further described below with reference to the drawings. The description is relatively detailed and complete, but it should not be construed as a limitation on the scope of the present invention patent. Obvious deformations and replacement forms of the following examples are all within the protection scope of this patent.
[0036] Since the existing Battery Management System (BMS) obtains the current maximum charging capacity of the battery by looking up a table in real time according to the State of Charge (SOC) and temperature of the current battery, when the current output by the charging pile exceeds a certain value or a certain time of the current maximum charging capacity of the battery, the voltage of the battery cell will be pulled up. Once the voltage of the battery cell is pulled up to reach the full charge threshold, the SOC will be incorrectly corrected to 100%. This is because the current full charge correction only considers the voltage of the battery cell, without considering factors such as the actual charging current of the battery, and lacks measures for handling abnormal situations.
[0037] The embodiment of the present application provides a method for full charge correction of SOC of a lithium iron phosphate battery. On the basis of only considering the voltage of the battery cell in the original full charge correction condition, this method also takes into account the influence of the actual output of the charging pile on the full charge correction of SOC, and can prevent the SOC from being incorrectly corrected to 100% due to the large current output by the charging pile.
[0038] Refer to Figure 1 , the method for full charge correction of SOC of the lithium iron phosphate battery includes:
[0039] S1. During the charging process of the lithium iron phosphate battery, if it is recognized that the voltage of the battery cell reaches the preset full charge condition, set the full charge flag bit.
[0040] S2. After the full charge flag bit is set, select to perform full charge correction on the SOC or exit charging according to the actual charging current of the battery before the full charge flag bit is set.
[0041] Among them, the method in the embodiment of the present application can be applied to the AC charging mode of the lithium iron phosphate battery, and can also be applied to the DC charging mode of the lithium iron phosphate battery. The specific charging method can be an AC charging method or a DC charging method.
[0042] Specifically, in the embodiment of the present application, after the vehicle starts charging, the Battery Management System (BMS) obtains parameters such as the highest cell voltage BcuCellUMax of the battery and the actual charging current BcuBattI of the battery in real time.
[0043] First, judge whether the highest cell voltage BcuCellUMax of the battery is ≥ the preset full charge threshold U 0 and the duration is ≥ the first preset duration t 0 , if it meets that the highest cell voltage BcuCellUMax of the battery is ≥ the preset full charge threshold U 0 and the duration is ≥ the first preset duration t 0 , then set the full charge flag bit (for example, set the full charge flag bit to 1).
[0044] Refer to Figure 2, after the full charge flag is set, obtain the actual charging current BcuBattI of the battery before the full charge flag is set. Determine whether the actual charging current BcuBattI of the battery before the full charge flag is set is < the rated capacity of the battery cell Cap_Ah * the maximum demand current LastStepChargRate_max at full charge + the pre-calibrated redundant current threshold I_TBD, and the duration is ≥ the second preset duration t1.
[0045] If it satisfies that the actual charging current BcuBattI of the battery before the full charge flag is set is < the rated capacity of the battery cell Cap_Ah * the maximum demand current LastStepChargRate_max at full charge + the pre-calibrated redundant current threshold I_TBD, and the duration is ≥ the second preset duration t1, then the full charge corrected SOC is 100%, send a prompt of full charge completed (fullofcharg), and correct the SOC to 100% to end the charging process; otherwise, do not correct the SOC to full charge, prompt the reason for ending the charge as "exited charging due to overcurrent during charging", and then end the charging process.
[0046] In the embodiment of the present application, the maximum demand current at full charge of the battery is determined by looking up a table, specifically referring to the maximum demand current corresponding to when the SOC is 100%, and this value can be obtained by looking up the table. Combining Table 1 below, it can be determined that the maximum demand current corresponding to when the S0C is 100% is 0.33A.
[0047]
[0048] Table 1
[0049] In summary, the control strategy proposed in this embodiment to solve the problem of incorrect SOC correction caused by abnormal large current during the charging of lithium iron phosphate batteries, after the full charge flag position 1, determines whether to correct the SOC to full charge by judging the size of the actual charging current of the battery before the full charge flag position 1 and the maximum look-up table current corresponding to 100% SOC. Applying this strategy can reduce the probability of incorrect SOC correction and provide a better experience for users.
[0050] Refer to Figure 3 , on the other hand, the present invention provides a device for correcting the SOC to full charge of a lithium iron phosphate battery, including:
[0051] A setting module 101, configured to set the full charge flag position during the charging process of the lithium iron phosphate battery if it is recognized that the monomer voltage of the battery reaches the preset full charge condition;
[0052] A correction module 102, configured to select whether to correct the SOC to full charge or not according to the actual charging current of the battery before the full charge flag is set after the full charge flag is set.
[0053] Further, the condition for the single cell voltage of the battery to reach the preset full charge condition is as follows:
[0054] The highest single cell voltage of the battery is greater than or equal to the preset full charge threshold and lasts for the first preset duration.
[0055] Further, the correction module 102 includes:
[0056] A charging current acquisition unit 1021, configured to acquire the actual charging current of the battery within a preset period before the full charge flag is set;
[0057] A correction unit 1022, configured to perform full charge correction on the SOC if the actual charging current of the battery is less than the preset current and lasts for the second preset duration before the full charge flag is set; otherwise, no full charge correction is performed on the SOC.
[0058] On the other hand, the present application further provides a control device, including a processor, a memory, and a program or instruction stored on the memory and executable on the processor. When the program or instruction is executed by the processor, the steps of the full charge correction of the SOC of the lithium iron phosphate battery as described above are implemented.
[0059] On the other hand, the present application further provides a vehicle, including the full charge correction device of the SOC of the lithium iron phosphate battery as described above.
[0060] It should be noted that the embodiments in this specification are all described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other.
[0061] Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.
[0062] It should also be noted that in this text, terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. This is for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the present invention. In addition, relative terms such as "first" and "second" are used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations, nor can they be construed as indicating or implying relative importance. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements does not include those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or terminal device comprising the element.
[0063] The technical solutions provided by the present invention have been introduced in detail above. Specific examples are used in this text to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only for helping to understand the present invention, and the content of this specification should not be construed as a limitation on the present invention. At the same time, for those of ordinary skill in the art, according to the present invention, there will be various forms of changes in the specific implementation manners and application scopes. It is not necessary and impossible to enumerate all the implementation manners here, and the obvious changes or variations derived therefrom are still within the protection scope of the present invention.
Claims
1. A method for correcting the SOC full charge of a lithium iron phosphate battery, characterized in that: include: During the charging process of the lithium iron phosphate battery, if it is identified that the single cell voltage of the battery reaches the preset full charge condition, the full charge flag is set; After the full charge flag is set, the SOC is fully charged or not fully charged according to the actual charging current of the battery before the full charge flag is set. Furthermore, the single cell voltage of the battery reaches the preset full charge condition: The highest single cell voltage of the battery is greater than or equal to a preset full charge threshold and lasts for a first preset time period.
2. The SOC full charge correction method of the lithium iron phosphate battery according to claim 1, characterized in that: The steps of selecting to perform full charge correction or exit charging of the SOC according to the actual charging current of the battery before the full charge mark is set include: Obtaining the actual charging current of the battery within a preset period of time before the full charge mark is set; Before the full charge flag is set, if the actual charging current of the battery is less than the preset current and is maintained for a second preset time, a full charge correction is performed on the SOC; otherwise, no full charge correction is performed on the SOC.
3. The SOC full charge correction method of the lithium iron phosphate battery according to claim 1, characterized in that: The preset current is equal to the sum of the preset product and a pre-calibrated redundant current threshold, and the preset product is equal to the product of the rated capacity of the battery cell and the maximum required current of the battery when fully charged.
4. The SOC full charge correction method of the lithium iron phosphate battery according to claim 3, characterized in that: The maximum required current of the battery when fully charged is determined by looking up the table.
5. The SOC full charge correction method of the lithium iron phosphate battery according to claim 1, characterized in that: The method further comprises: If the SOC is fully charged, a prompt indicating that charging is complete is output and charging is terminated; If the SOC is not fully charged and corrected, an abnormal prompt will be output that the charging is exited due to the charging current exceeding the limit, and the charging will be terminated.
6. A SOC full charge correction device for a lithium iron phosphate battery, characterized in that: include: A setting module is used to set a full charge flag position when it is identified that the single cell voltage of the battery reaches a preset full charge condition during the charging process of the lithium iron phosphate battery; The correction module is used to select whether to perform full charge correction or not to perform full charge correction on the SOC according to the actual charging current of the battery before the full charge flag is set, after the full charge flag is set.
7. The SOC full charge correction device for a lithium iron phosphate battery according to claim 6, characterized in that: The battery cell voltage reaches the preset full charge condition: The highest single cell voltage of the battery is greater than or equal to a preset full charge threshold and lasts for a first preset time period.
8. The SOC full charge correction device for a lithium iron phosphate battery according to claim 6, characterized in that: The correction modules include: A charging current acquisition unit, used to acquire the actual charging current of the battery within a preset period of time before the full charge mark is set; The correction unit is used to make a full charge correction to the SOC before the full charge flag is set, if the actual charging current of the battery is less than the preset current and is maintained for a second preset time; otherwise, no full charge correction is made to the SOC.
9. A control device, characterized in that: It includes a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein when the program or instruction is executed by the processor, the steps of fully charging the SOC of the lithium iron phosphate battery as described in any one of claims 1 to 5 are implemented.
10. A vehicle, characterized in that: A SOC full-charge correction device for a lithium iron phosphate battery comprising any one of claims 6-8.