Soc correction method, energy storage device

Abstract

The application provides a SOC correction method and an energy storage device. The method is suitable for a lithium iron phosphate battery and includes the following steps: determining a starting state of charge of the lithium iron phosphate battery based on a voltage variation of the lithium iron phosphate battery, wherein the starting state of charge includes a first voltage starting state of charge and a second voltage starting state of charge, and the first voltage starting state of charge and the second voltage starting state of charge correspond to different starting voltage values; determining a SOC target value of the lithium iron phosphate battery according to the starting state of charge and a battery voltage value of the lithium iron phosphate battery; and correcting a SOC display value of the lithium iron phosphate battery according to the SOC target value. The application aims to correct the SOC display value of the lithium iron phosphate battery, so that the SOC display value of the lithium iron phosphate battery is more accurate.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a SOC correction method and an energy storage device. Background Technology

[0002] Currently, lithium iron phosphate (LFP) batteries are widely used in large-scale grid-connected energy storage. Because LFP batteries are charged before they have been sufficiently rested, their voltage rises very quickly at the end of the charge cycle. This causes the SOC (State of Charge, also known as remaining capacity) of the LFP battery to increase rapidly at the end of the charge cycle, or to remain at a certain value for an extended period. Consequently, the displayed SOC value at the end of the charge cycle cannot accurately reflect the remaining capacity. Summary of the Invention

[0003] The main objective of this application is to provide a SOC correction method and an energy storage device, which aims to correct the SOC display value of a lithium iron phosphate battery so that the SOC display value of the lithium iron phosphate battery is more accurate at the end of charging.

[0004] To achieve the above objectives, this application provides a SOC correction method applicable to lithium iron phosphate batteries, the method comprising:

[0005] Based on the voltage change of the lithium iron phosphate battery, the initial charging state of the lithium iron phosphate battery is determined, wherein the initial charging state includes a first voltage initial charging state and a second voltage initial charging state, and the first voltage initial charging state and the second voltage initial charging state correspond to different initial voltage values.

[0006] Based on the initial charging state and the battery voltage value of the lithium iron phosphate battery, the SOC target value of the lithium iron phosphate battery is determined;

[0007] The SOC display value of the lithium iron phosphate battery is corrected based on the target SOC value.

[0008] In addition, to achieve the above objectives, this application also provides an energy storage device, which includes a memory and a processor; wherein the memory is connected to the processor and is used to store a program; the processor is used to implement the steps of the SOC correction method as described in any one of the embodiments of this application by running the program stored in the memory.

[0009] This application proposes a SOC correction method and energy storage device that can determine the initial charging state of a lithium iron phosphate (LFP) battery as either a first voltage initial charging state or a second voltage initial charging state based on the voltage change of the LFP battery. Furthermore, a target SOC value for the LFP battery can be determined based on the initial charging state and the battery voltage, and the displayed SOC value of the LFP battery can be corrected according to the target SOC value. Through the above technical means, SOC correction can be achieved at the end of the charging process of the LFP battery based on different initial charging states and battery voltage values, thereby solving the technical problem in traditional technologies where the SOC of LFP batteries increases rapidly at the end of the charging process or remains at a certain value for a long time, thus improving the accuracy of the displayed SOC value of the LFP battery at the end of the charging process. Attached Figure Description

[0010] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram illustrating the steps of a SOC correction method provided in an embodiment of this application;

[0012] Figure 2 A schematic diagram of the voltage change curve of a lithium iron phosphate battery during the charging process, provided for an embodiment of this application;

[0013] Figure 3 A schematic diagram illustrating the steps for determining the SOC target value of a lithium iron phosphate battery, provided in an embodiment of this application;

[0014] Figure 4 A schematic diagram illustrating the steps for determining the charging stage of a lithium iron phosphate battery, as provided in this application embodiment;

[0015] Figure 5 A schematic diagram illustrating another step for determining the charging stage of a lithium iron phosphate battery, provided as an embodiment of this application.

[0016] Figure 6 This is a schematic diagram illustrating the steps for correcting the SOC display value provided in an embodiment of this application;

[0017] Figure 7 This is a schematic diagram illustrating the effect of correcting the SOC display value in the first embodiment of this application.

[0018] Figure 8This is a schematic diagram illustrating the effect of correcting the SOC display value in a second way, as provided in an embodiment of this application.

[0019] Figure 9 This is a schematic diagram illustrating the effect of correcting the SOC display value in a third way, as provided in the embodiments of this application.

[0020] Figure 10 This is a schematic diagram illustrating the effect of correcting the SOC display value in the fourth embodiment of this application.

[0021] Figure 11 This is a schematic diagram illustrating the effect of correcting the SOC display value in the fifth embodiment of this application.

[0022] Figure 12 This is a schematic diagram illustrating the effect of the sixth correction of the SOC display value provided in the embodiments of this application;

[0023] Figure 13 This is a schematic diagram of the structure of the energy storage device provided in the embodiments of this application.

[0024] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0027] The electrical characteristics of lithium iron phosphate (LFP) batteries differ significantly from those of ternary lithium batteries. When an LFP battery starts charging at a high voltage and is not fully rested, its voltage rises very rapidly towards the end of the charge. This electrical characteristic causes the State of Charge (SOC) reading, calculated based on the rapidly rising battery voltage at the end of the charge, to either increase too quickly or remain at a certain value for an extended period. In other words, when the LFP battery is not fully rested, the SOC reading at the end of the charge may be artificially high due to the rapid voltage increase, or artificially low due to the continuous charging despite a constant battery voltage. Therefore, in conventional technology, the SOC reading at the end of the charge for an LFP battery that has not been fully rested does not accurately reflect the remaining charge.

[0028] Please see Figure 1 , Figure 1 This diagram illustrates the steps of a SOC correction method provided in an embodiment of this application. This SOC correction method can be applied to energy storage devices with lithium iron phosphate batteries, thereby correcting the displayed SOC value of the lithium iron phosphate battery.

[0029] like Figure 1 As shown, the SOC correction method includes steps S11 to S13.

[0030] Step S11: Determine the initial charging state of the lithium iron phosphate battery based on the voltage change of the lithium iron phosphate battery.

[0031] Understandably, when a lithium iron phosphate battery is charging, its voltage increases with the charging time. Therefore, the initial charging state of the lithium iron phosphate battery can be determined based on the voltage change.

[0032] The initial charging state includes a first voltage initial charging state and a second voltage initial charging state, with the first voltage initial charging state and the second voltage initial charging state corresponding to different initial voltage values.

[0033] This application uses the example of a first voltage-initiated charging state being a low-voltage initiated charging state and a second voltage-initiated charging state being a high-voltage initiated charging state for illustration. It can be understood that the low-voltage initiated charging state refers to the state in which the lithium iron phosphate battery starts charging from a low voltage; the high-voltage initiated charging state refers to the state in which the lithium iron phosphate battery starts charging from a high voltage.

[0034] It should be noted that this application does not limit the specific voltage values ​​for the aforementioned low and high voltages. For example, when the lithium iron phosphate battery begins charging at a voltage within the range of 0V-1800mV, it corresponds to the first voltage starting charging state, i.e., the low voltage starting charging state; when the lithium iron phosphate battery begins charging at a voltage greater than 1800mV, it corresponds to the second voltage starting charging state, i.e., the high voltage starting charging state. Of course, the aforementioned starting charging voltage value for the lithium iron phosphate battery can also be other values, and this application does not limit this.

[0035] Optionally, determining the initial charging state of the lithium iron phosphate battery based on the voltage change of the lithium iron phosphate battery may further include: obtaining the time interval between the battery voltage value of the lithium iron phosphate battery rising from a first value to a second value; if the time interval is greater than a preset time interval, then the initial charging state is determined to be a first voltage initial charging state; if the time interval is less than or equal to the preset time interval, then the initial charging state is determined to be a second voltage initial charging state.

[0036] It should be noted that the first value mentioned above can be 3480mV, the second value can be 3500mV, and the preset time interval is 90s. This application uses this as an example for illustration. Of course, the first value, the second value, and the preset time interval can also be other values, and this application does not limit them.

[0037] Specifically, the time interval during which the lithium iron phosphate battery voltage rises from 3480mV to 3500mV can be obtained. Then, it is determined whether this time interval is greater than or less than 90s. If the time interval is greater than 90s, the lithium iron phosphate battery is determined to be in the first voltage initial charging state; if the time interval is less than or equal to 90s, the lithium iron phosphate battery is determined to be in the second voltage initial charging state.

[0038] Optionally, a voltage change curve can be obtained by fitting the voltage change of the lithium iron phosphate battery, and then the initial charging state of the lithium iron phosphate battery can be determined based on the voltage change curve of the lithium iron phosphate battery.

[0039] Please see Figure 2 , Figure 2 This is a schematic diagram illustrating the voltage change curve of a lithium iron phosphate battery during charging, as provided in an embodiment of this application. Figure 2 As shown, when the lithium iron phosphate battery is in the initial charging state at the first voltage, its subsequent voltage change curve will appear as follows. Figure 2 The stages from P1 to P3; when the lithium iron phosphate battery is in the second voltage initial charging state, its subsequent battery voltage change curve during the charging process will appear as follows. Figure 2 The P4 to P5 stage.

[0040] In this embodiment, the initial charging state of the lithium iron phosphate battery can be determined based on the voltage change. Alternatively, a voltage change curve can be fitted based on the voltage change, and then the initial charging state can be determined based on the voltage change curve. This method enables the determination of the initial charging state of the lithium iron phosphate battery, allowing for correction of the battery's SOC display value based on different initial charging states. In this embodiment, by correcting the SOC display value at each stage of each initial charging state, the SOC display value accurately reflects the remaining charge of the lithium iron phosphate battery at each stage.

[0041] Step S12: Determine the target SOC value of the lithium iron phosphate battery based on the initial charging state and the battery voltage value of the lithium iron phosphate battery.

[0042] Once the initial state of charge and battery voltage of the lithium iron phosphate battery are determined, the corresponding SOC target value can be determined based on the initial state of charge and battery voltage.

[0043] It should be noted that this application does not limit the method for determining the SOC target value of the lithium iron phosphate battery. For example, the SOC target value can be determined directly based on the initial charging state of the lithium iron phosphate battery and the correspondence between the battery voltage value and the SOC target value; alternatively, the SOC displayed value of the lithium iron phosphate battery can be determined, and then the SOC target value can be determined by relevant formulas based on the initial charging state of the lithium iron phosphate battery, the battery voltage value, and the SOC displayed value.

[0044] In this embodiment of the application, the target SOC value of the lithium iron phosphate battery can be determined based on the initial charging state and the battery voltage value of the lithium iron phosphate battery, so as to correct the displayed SOC value of the lithium iron phosphate battery.

[0045] Step S13: Correct the displayed SOC value of the lithium iron phosphate battery according to the target SOC value.

[0046] Once the target SOC value is determined, the displayed SOC value of the lithium iron phosphate battery can be corrected based on the target SOC value.

[0047] It should be noted that this application does not limit the method for correcting the SOC display value of lithium iron phosphate batteries. For example, the charging catch-up rate of the lithium iron phosphate battery can be determined based on the target SOC value, and then the SOC display value can be corrected based on the charging catch-up rate; alternatively, the SOC display value of the lithium iron phosphate battery can be directly corrected based on the target SOC value. In this way, the difference between the target SOC value and the displayed SOC value of the lithium iron phosphate battery can be reduced.

[0048] The SOC correction method proposed in this application can determine the initial charging state of a lithium iron phosphate battery (LFP) battery as either a first voltage initial charging state or a second voltage initial charging state based on the voltage change. Furthermore, a target SOC value for the LFP battery can be determined based on the initial charging state and the battery voltage, and the displayed SOC value is corrected accordingly. This technical approach enables SOC correction at the end of the charging process, thus solving the problem in traditional technologies where the LFP battery is not sufficiently rested, resulting in rapid SOC growth or prolonged stagnation at a certain value at the end of charging. This improves the accuracy of the displayed SOC value at the end of the charging process.

[0049] Please see Figure 3 , Figure 3This is a schematic diagram illustrating the steps for determining the target SOC value of a lithium iron phosphate battery, as provided in an embodiment of this application. Figure 3 As shown, the SOC target value of the lithium iron phosphate battery can be determined based on the initial charging state and the battery voltage value of the lithium iron phosphate battery through steps S121 to S123.

[0050] Step S121: Obtain the battery voltage value of the lithium iron phosphate battery.

[0051] Step S122: Determine the charging stage of the lithium iron phosphate battery based on the battery voltage and initial charging state.

[0052] Specifically, the battery voltage value of the lithium iron phosphate battery can be obtained, and then the charging stage of the lithium iron phosphate battery can be determined based on its corresponding initial charging state and battery voltage value. For example, when the lithium iron phosphate battery is in the first initial charging state or the second initial charging state, the charging stage of the battery in different initial charging states can be further determined based on its corresponding battery voltage value.

[0053] It should be noted that this application does not limit the method for determining the charging stage of the lithium iron phosphate battery, such as a first initial charging state or a second initial charging state. The battery voltage range corresponding to each charging stage can be divided separately. Then, after obtaining the battery voltage value of the lithium iron phosphate battery, the battery voltage range within which the battery voltage value falls can be determined, thereby determining its corresponding charging stage. Furthermore, after obtaining the battery voltage value, the corresponding charging current value can be further determined to use both the battery voltage value and the charging current value to jointly determine the charging stage.

[0054] Step S123: Determine the SOC target value based on the battery voltage value and its corresponding charging stage.

[0055] Once the battery voltage and charging stage of the lithium iron phosphate battery are determined, the target SOC value can be determined based on the battery voltage and the corresponding charging stage.

[0056] It should be noted that this application does not limit the determination of the SOC target value of the lithium iron phosphate battery. For example, the SOC target value can be determined directly based on the battery voltage value of the lithium iron phosphate battery and the correspondence between the charging stage and the SOC target value; alternatively, the SOC displayed value of the lithium iron phosphate battery can be determined, and then the SOC target value can be determined by relevant formulas based on the battery voltage value, charging stage, and SOC displayed value of the lithium iron phosphate battery.

[0057] Understandably, compared to determining the SOC target value of a lithium iron phosphate battery based on its initial charging state and voltage, this application further subdivides the charging stage of the lithium iron phosphate battery to determine its specific charging stage. This makes the SOC target value determined based on the battery voltage and its corresponding charging stage more accurate, resulting in a better SOC correction effect.

[0058] In the embodiments of this application, the charging stage of the lithium iron phosphate battery can be further determined, and the SOC target value of the lithium iron phosphate battery can be determined based on the charging stage and battery voltage value, so as to correct the SOC display value of the lithium iron phosphate battery, thereby achieving a better correction effect.

[0059] Please see Figure 4 , Figure 4 This is a schematic diagram illustrating the steps for determining the charging stage of a lithium iron phosphate battery, as provided in an embodiment of this application. Figure 4 As shown, the charging stage of the lithium iron phosphate battery can be determined based on the battery voltage value and the initial charging state through steps S1221 to S1224.

[0060] Step S1221: If the initial charging state is the first voltage initial charging state, then obtain the charging current value of the lithium iron phosphate battery.

[0061] Step S1222: When the battery voltage is less than the first voltage threshold and the charging current is the first current threshold, the charging stage of the lithium iron phosphate battery is determined to be the first charging stage.

[0062] It should be noted that this application refers to the first voltage threshold V. A First current threshold I A The specific value is not limited, for example, the first voltage threshold V A It can be 3500mV, the first current threshold I A This application uses 1C as an example for illustration.

[0063] Understandably, when the lithium iron phosphate battery is in the initial charging state at the first voltage, the current charging current value can be obtained. Therefore, when the lithium iron phosphate battery voltage is less than 3500mV and the charging current is 1C, the charging stage of the lithium iron phosphate battery is determined to be the first charging stage.

[0064] Step S1223: When the battery voltage value is within the range of the first voltage threshold and the second voltage threshold, and the charging current value is the second current threshold, the charging stage of the lithium iron phosphate battery is determined to be the second charging stage.

[0065] Wherein, the second voltage threshold V BGreater than the first voltage threshold V A Second current threshold I B Less than the first current threshold I A .

[0066] It should be noted that this application refers to the second voltage threshold V. B Second current threshold I B The specific value is not limited, for example, the second voltage threshold V B It can be 3550mV, the second current threshold I B The value is 0.5C, and this application will use this as an example for illustration.

[0067] Understandably, when the lithium iron phosphate battery is in the first voltage initial charging state, with the battery voltage value in the range of 3500mV and 3550mV and the charging current value of 0.5C, the charging stage of the lithium iron phosphate battery can be determined as the second charging stage.

[0068] Step S1224: When the battery voltage is greater than the second voltage threshold and the charging current is the third current threshold, the charging stage of the lithium iron phosphate battery is determined to be the third charging stage.

[0069] Among them, the third current threshold I C Less than the second current threshold I B .

[0070] It should be noted that this application refers to the third current threshold I. C The specific value is not limited, for example, the third current threshold I C It can be 0.2C, and this application will use this as an example for illustration.

[0071] Understandably, when the lithium iron phosphate battery is in the first voltage initial charging state, with a battery voltage greater than 3550mV and a charging current of 0.2C, the charging stage of the lithium iron phosphate battery can be determined as the third charging stage. It should be noted that in this application, the unit C of the current threshold value is related to the capacity of the lithium iron phosphate battery. For example, if the capacity of the lithium iron phosphate battery is 3600mAh, a charging current of 1C indicates a charging current of 3600mA; a charging current of 0.5C indicates a charging current of 1800mA.

[0072] In this embodiment of the application, when the lithium iron phosphate battery is in the first starting voltage charging state, the charging current value can be obtained, and then the charging stage of the lithium iron phosphate battery can be determined based on the battery voltage value and the charging current value.

[0073] Based on the above embodiments, the SOC target value of the lithium iron phosphate battery is determined according to the initial charging state and the battery voltage value of the lithium iron phosphate battery, including: when the lithium iron phosphate battery is in the first charging stage or the second charging stage, if the battery voltage value is not greater than the third voltage threshold and the SOC display value is greater than the first preset value, the first preset value is used as the SOC target value; when the lithium iron phosphate battery is in the second charging stage and the battery voltage value is greater than the third voltage threshold, the SOC target value is determined according to the battery voltage value and the first correspondence; when the lithium iron phosphate battery is in the third charging stage and the battery voltage value is greater than the fourth voltage threshold, the SOC target value is determined according to the battery voltage value and the second correspondence.

[0074] The third voltage threshold is less than the second voltage threshold, and the third voltage threshold is greater than the first voltage threshold.

[0075] It should be noted that this application refers to the third voltage threshold V. C The specific value of the first preset value is not limited. For example, the third voltage threshold V C The value is 3530mV, and the first preset value is 94%. This application will use this as an example for illustration.

[0076] Understandably, when a lithium iron phosphate battery is in the first or second charging stage, if the battery voltage is no greater than 3530mV and the SOC display value is greater than 94%, it means that the current SOC display value is greater than the actual SOC value corresponding to the battery voltage. Therefore, 94% is used as the SOC target value to correct the SOC display value.

[0077] Furthermore, when the lithium iron phosphate battery is in the second charging stage and the battery voltage is greater than 3530mV, the SOC target value is determined based on the battery voltage and the first correspondence.

[0078] It should be noted that the first correspondence is established through the third voltage threshold V. C Corresponding to the first preset value and the second voltage threshold V B The first preset value is less than the second preset value, and the second preset value is determined accordingly. Furthermore, the second preset value can be 96%, but this application does not limit it in this regard.

[0079] Specifically, the SOC target value can be determined using the following formula:

[0080] SOC target value = A*Volt+B, where Volt is the battery voltage value.

[0081] Furthermore, a third voltage threshold V can be selected. C Corresponding to the first preset value, namely (3530, 94) and the second voltage threshold V BThe second preset value, (3550, 96), is substituted into the above formula to determine the values ​​of A and B, resulting in A = 0.1 and B = -259.

[0082] That is, the first correspondence is: SOC target value = 0.1 * Volt - 259, where Volt is the battery voltage value.

[0083] Thus, after determining the battery voltage value, the SOC target value can be determined based on the first correspondence.

[0084] Furthermore, the third preset value V C Less than the fourth preset value, fourth voltage threshold V D Less than the first voltage threshold V A Fifth voltage threshold V E Greater than the third voltage threshold V C And less than the second voltage threshold V B This application addresses the fourth voltage threshold V. D Fifth voltage threshold V E The specific value of the fourth preset value is not limited. For example, the fourth voltage threshold V D It is 3450mV, the fifth voltage threshold V E The value is 3540mV, and the fourth preset value is 99%.

[0085] Understandably, when the lithium iron phosphate battery is in the third charging stage and the battery voltage is greater than 3450mV, the SOC target value can be determined based on the battery voltage value and the corresponding relationship between the two.

[0086] The second correspondence is achieved through the fourth voltage threshold V. D Corresponding to the third preset value and the fifth voltage threshold V E This corresponds to the fourth preset value.

[0087] Specifically, the SOC target value can be determined using the following formula:

[0088] SOC target value = C * Volt + D, where Volt is the battery voltage value.

[0089] Furthermore, a fourth voltage threshold V can be selected. D Corresponding to the third preset value, namely (3450, 96) and the fifth voltage threshold V E The fourth preset value, (3540, 99), is substituted into the above formula to determine the values ​​of C and D, resulting in C = 0.0333 and D = -19.

[0090] That is, the second correspondence is: SOC target value = 0.0333 * Volt - 19, where Volt is the battery voltage value.

[0091] Thus, after determining the battery voltage value, the SOC target value can be determined based on the second correspondence.

[0092] In this embodiment of the application, when the lithium iron phosphate battery is in the first starting voltage charging state, the SOC target value can be determined according to the charging stage of the lithium iron phosphate battery and the corresponding battery voltage value, so as to correct the SOC display value of the lithium iron phosphate battery.

[0093] Please continue reading. Figure 5 , Figure 5 This is a schematic diagram illustrating another step in determining the charging stage of a lithium iron phosphate battery, provided as an embodiment of this application. Figure 5 As shown, steps S1225 to S1227 can also be used to determine the charging stage of the lithium iron phosphate battery based on the battery voltage value and the initial charging state.

[0094] Step S1225: If the initial charging state is the second voltage initial charging state, then obtain the charging current value of the lithium iron phosphate battery.

[0095] Step S1226: When the battery voltage is less than the sixth voltage threshold and the charging current is the fourth current threshold, the charging stage of the lithium iron phosphate battery is determined to be the fourth charging stage.

[0096] It should be noted that this application refers to the sixth voltage threshold V. F Fourth current threshold I D The specific value is not limited, for example, the sixth voltage threshold V F It can be 3500mV, the fourth current threshold I D This application uses 1C as an example for illustration.

[0097] Understandably, when the lithium iron phosphate battery is in the second voltage initial charging state, the current charging current value can be obtained. Therefore, when the lithium iron phosphate battery voltage is less than 3500mV and the charging current is 1C, the charging stage of the lithium iron phosphate battery is determined to be the fourth charging stage.

[0098] Preferably, the first charging stage of the lithium iron phosphate battery under the first voltage starting charging state and the fourth charging stage under the second voltage starting charging state can have the same voltage threshold and current threshold, and this application does not limit this.

[0099] Step S1227: When the battery voltage is within the range of the sixth and seventh voltage thresholds and the charging current is the fifth current threshold, the charging stage of the lithium iron phosphate battery is determined to be the fifth charging stage.

[0100] Among them, the sixth voltage threshold V F Less than the seventh voltage threshold V G Fourth current threshold I D Greater than the fifth current threshold I E .

[0101] It should be noted that this application refers to the seventh voltage threshold V. G Fourth current threshold I D The specific value is not limited, for example, the seventh voltage threshold V G It can be 3550mV, the fourth current threshold I D The value is 0.5C, and this application will use this as an example for illustration.

[0102] Understandably, when the lithium iron phosphate battery is in the second voltage initial charging state, with the battery voltage value in the range of 3500mV and 3550mV and the charging current value of 0.5C, it can be determined that the lithium iron phosphate battery is in the fifth charging stage.

[0103] Preferably, the second charging stage of the lithium iron phosphate battery under the first voltage starting charging state and the fifth charging stage under the second voltage starting charging state can have the same voltage threshold and current threshold, and this application does not limit this.

[0104] In this embodiment of the application, when the lithium iron phosphate battery is in the second starting voltage charging state, the charging current value can be obtained, and then the charging stage of the lithium iron phosphate battery can be determined based on the battery voltage value and the charging current value.

[0105] Optionally, determining the SOC target value of the lithium iron phosphate battery based on the initial charging state and the battery voltage value of the lithium iron phosphate battery further includes: when the lithium iron phosphate battery is in the fourth charging stage and the displayed SOC value is greater than the fifth preset value, using the fifth preset value as the SOC target value; and when the lithium iron phosphate battery is in the fifth charging stage, determining the SOC target value based on the battery voltage value and the third correspondence.

[0106] It should be noted that this application does not limit the specific value of the fifth preset value. For example, if the fifth preset value is 94%, this application will use this as an example for illustration.

[0107] Understandably, when a lithium iron phosphate battery is in the fourth charging stage, if the displayed SOC value is greater than 94%, then 94% will be used as the target SOC value.

[0108] Furthermore, when the lithium iron phosphate battery is in the fifth charging stage, the SOC target value can be determined based on the battery voltage value and the third corresponding relationship.

[0109] It should be noted that the third correspondence is established through the seventh voltage threshold V. G Corresponding to the sixth preset value and the eighth voltage threshold V H The seventh voltage threshold V is determined in accordance with the fifth preset value. G Greater than the eighth voltage threshold V H The sixth preset value is greater than the fifth preset value.

[0110] Furthermore, the seventh voltage threshold V G It can be 3550mV, the sixth preset value is 99%, and the eighth voltage threshold is V. H The value is 3430mV, but this application does not limit it.

[0111] Specifically, the SOC target value can be determined using the following formula:

[0112] SOC target value = E*Volt + F, where Volt is the battery voltage value.

[0113] Furthermore, a seventh voltage threshold V can be selected. G Corresponding to the sixth preset value, namely (3550, 99) and the eighth voltage threshold V H The fifth preset value, (3430, 94), is substituted into the above formula to determine the values ​​of E and F, yielding E = 0.0416 and F = -48.9.

[0114] That is, the third correspondence is: SOC target value = 0.0416 * Volt - 48.9, where Volt is the battery voltage value.

[0115] Thus, after determining the battery voltage value, the SOC target value can be determined based on the third correspondence.

[0116] In this embodiment of the application, when the lithium iron phosphate battery is in the second starting voltage charging state, the SOC target value can be determined according to the charging stage of the lithium iron phosphate battery and the corresponding battery voltage value, so as to correct the SOC display value of the lithium iron phosphate battery.

[0117] Please continue reading. Figure 6 , Figure 6 This is a schematic diagram illustrating the steps for correcting the SOC display value provided in an embodiment of this application. Figure 6 As shown, the SOC display value of the lithium iron phosphate battery can be corrected according to the SOC target value through steps S131 to S132.

[0118] Step S131: Determine the charging catch-up rate of the lithium iron phosphate battery based on the target SOC value and the displayed SOC value.

[0119] Specifically, the charging catch-up rate of lithium iron phosphate batteries can be determined based on the target SOC value and the displayed SOC value using the following formula:

[0120] Charging catch-up rate = 1 + k * (SOC target value – SOC displayed value) / (1 – SOC target value)

[0121] Where k is a coefficient that can be modified according to the debugging situation. At the same time, the dynamic catch-up ratio is limited, but this application does not impose any restrictions on it.

[0122] Step S132: Correct the SOC display value based on the charging catch-up rate.

[0123] Optionally, the SOC display value is corrected based on the charging catch-up rate, including: multiplying the charging catch-up rate by the SOC change in a single operating cycle of the lithium iron phosphate battery to obtain the SOC catch-up value; and summing the SOC catch-up value and the SOC display value to obtain the corrected SOC display value.

[0124] Specifically, the SOC display value can be corrected based on the charging catch-up rate using the following formula:

[0125] SOC catch-up value = Delta SOC * Dynamic catch-up ratio

[0126] Delta SOC is the change in SOC of a lithium iron phosphate battery during a single operating cycle.

[0127] Corrected SOC display value = SOC catch-up value + SOC display value

[0128] This allows us to obtain the corrected SOC display value.

[0129] It should be noted that the greater the difference between the target SOC value and the displayed SOC value, the faster the correction rate; the closer the target SOC value is to 100, the faster the correction rate. Furthermore, before the lithium iron phosphate battery triggers charging overvoltage, the maximum displayed SOC value is limited to 99%; when the lithium iron phosphate battery triggers charging overvoltage, the displayed SOC value increases from 99% to 100%.

[0130] In this embodiment, the charging catch-up rate of the lithium iron phosphate battery can be determined based on the target SOC value and the displayed SOC value. Then, the displayed SOC value can be corrected by the charging catch-up rate, thereby solving the technical problem in the traditional technology that the SOC of the lithium iron phosphate battery increases too quickly at the end of charging or stays at a certain value for a long time, so as to improve the user experience.

[0131] like Figure 7 As shown, L2 is the SOC display value change curve before correction; L1 is the SOC display value change curve after correction. Through the SOC correction method of this application embodiment, the SOC display value of the lithium iron phosphate battery increases linearly to 100% under the first voltage initial charging state, solving the problem that the SOC value jumps directly from 98% to 100% before correction.

[0132] like Figure 8 As shown, L4 is the SOC display value change curve before correction; L3 is the SOC display value change curve after correction. Through the SOC correction method of this application embodiment, the SOC display value of the lithium iron phosphate battery increases rapidly in the first voltage initial charging state, solving the problem of the SOC changing directly from 90% to 100% before correction.

[0133] like Figure 9 As shown, L6 is the SOC display value change curve before correction; L5 is the SOC display value change curve after correction. Through the SOC correction method of this application embodiment, the SOC display value of the lithium iron phosphate battery at the first voltage starting charging state decelerates and increases linearly to 100% when it is about to finish charging, thus solving the problem that the SOC continued to charge after rising to 100% before correction.

[0134] like Figure 10 As shown, L8 is the SOC display value change curve before correction; L7 is the SOC display value change curve after correction. Through the SOC correction method of this application embodiment, the SOC display value of the lithium iron phosphate battery rises linearly to 100% in the second voltage initial charging state without sudden change, solving the problem that the SOC remains at a certain value for a long time before correction.

[0135] like Figure 11 As shown, L10 is the SOC display value change curve before correction; L9 is the SOC display value change curve after correction. Through the SOC correction method of this application embodiment, the SOC display value of the lithium iron phosphate battery increases rapidly in the second voltage initial charging state, solving the problem of the SOC changing abruptly from 90% to 100% before correction.

[0136] like Figure 12 As shown, L12 is the SOC display value change curve before correction; L11 is the SOC display value change curve after correction. Through the SOC correction method of this application embodiment, the SOC display value of the lithium iron phosphate battery in the second voltage initial charging state decelerates and increases linearly to 100% when it is about to finish charging, thus solving the problem that the SOC continued to charge after rising to 100% before correction.

[0137] The methods and apparatus of this application can be used in a wide variety of general-purpose or special-purpose computing system environments or configurations. For example: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer terminal devices, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, etc.

[0138] For example, the above-described methods and apparatus can be used in energy storage devices, and computer programs can be used in such applications. Figure 13 It operates on the energy storage device shown.

[0139] Please see Figure 13 , Figure 13 This is a schematic diagram of the energy storage device provided in an embodiment of this application.

[0140] like Figure 13 As shown, the energy storage device includes a processor, a memory, and a network interface connected via a system bus. The memory may include volatile storage media, non-volatile storage media, and internal memory.

[0141] Non-volatile storage media can store operating systems and computer programs. These computer programs include program instructions that, when executed, cause the processor to perform steps of any SOC modification method.

[0142] The processor provides computing and control capabilities to support the operation of the entire energy storage device.

[0143] Internal memory provides an environment for the execution of computer programs in non-volatile storage media, which, when executed by a processor, enable the processor to perform the steps of any SOC correction method.

[0144] This network interface is used for network communication, such as sending assigned tasks. Those skilled in the art will understand that the structure of this energy storage device is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the energy storage device to which the present application is applied. Specific energy storage devices may include more or fewer components than shown in the diagram, or combine certain components, or have different component arrangements.

[0145] It should be understood that the processor can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Among these, a general-purpose processor can be a microprocessor or any conventional processor.

[0146] In some embodiments, the processor is used to run a computer program stored in a memory to perform the following steps: determining the initial charging state of the lithium iron phosphate battery based on the voltage change of the lithium iron phosphate battery, wherein the initial charging state includes a first voltage initial charging state and a second voltage initial charging state, the first voltage initial charging state and the second voltage initial charging state corresponding to different initial voltage values; determining the SOC target value of the lithium iron phosphate battery according to the initial charging state and the battery voltage value of the lithium iron phosphate battery; and correcting the SOC display value of the lithium iron phosphate battery according to the SOC target value.

[0147] In some embodiments, the processor is further configured to acquire the battery voltage value of the lithium iron phosphate battery; determine the charging stage of the lithium iron phosphate battery based on the battery voltage value and the initial charging state; and determine the SOC target value based on the battery voltage value and the corresponding charging stage.

[0148] In some embodiments, the processor is further configured to: acquire the charging current value of the lithium iron phosphate battery when the initial charging state is the first voltage initial charging state; determine the charging stage of the lithium iron phosphate battery as a first charging stage when the battery voltage value is less than a first voltage threshold and the charging current value is a first current threshold; determine the charging stage of the lithium iron phosphate battery as a second charging stage when the battery voltage value is within the range of the first voltage threshold and a second voltage threshold and the charging current value is a second current threshold; and determine the charging stage of the lithium iron phosphate battery as a third charging stage when the battery voltage value is greater than the second voltage threshold and the charging current value is a third current threshold; wherein the second voltage threshold is greater than the first voltage threshold, the second current threshold is less than the first current threshold, and the third current threshold is less than the second current threshold.

[0149] In some embodiments, the processor is further configured to: when the lithium iron phosphate battery is in the first charging stage or the second charging stage, if the battery voltage value is not greater than a third voltage threshold and the displayed SOC value is greater than a first preset value, use the first preset value as the SOC target value, wherein the third voltage threshold is less than the second voltage threshold and the third voltage threshold is greater than the first voltage threshold; when the lithium iron phosphate battery is in the second charging stage and the battery voltage value is greater than the third voltage threshold, determine the SOC target value according to the battery voltage value and a first correspondence, wherein the first correspondence is determined by the third voltage threshold corresponding to the first preset value and the second voltage threshold corresponding to the second preset value, wherein the first preset value is less than the second preset value; when the lithium iron phosphate battery is in the third charging stage and the battery voltage value is greater than a fourth voltage threshold, determine the SOC target value according to the battery voltage value and a second correspondence, wherein the second correspondence is determined by the fourth voltage threshold corresponding to the third preset value and the fifth voltage threshold corresponding to the fourth preset value, wherein the third preset value is less than the fourth preset value, the fourth voltage threshold is less than the first voltage threshold, and the fifth voltage threshold is greater than the third voltage threshold and less than the second voltage threshold.

[0150] In some embodiments, the processor is further configured to: when the initial charging state is the second voltage initial charging state, acquire the charging current value of the lithium iron phosphate battery; when the battery voltage value is less than a sixth voltage threshold and the charging current value is a fourth current threshold, determine that the lithium iron phosphate battery is in a fourth charging stage; when the battery voltage value is within the range of the sixth voltage threshold and the seventh voltage threshold, and the charging current value is a fifth current threshold, determine that the lithium iron phosphate battery is in a fifth charging stage, wherein the sixth voltage threshold is less than the seventh voltage threshold, and the fourth current threshold is greater than the fifth current threshold.

[0151] In some embodiments, the processor is further configured to: when the lithium iron phosphate battery is in the fourth charging stage and the displayed SOC value is greater than a fifth preset value, use the fifth preset value as the SOC target value; when the lithium iron phosphate battery is in the fifth charging stage, determine the SOC target value according to the battery voltage value and a third correspondence, wherein the third correspondence is determined by the seventh voltage threshold corresponding to the sixth preset value and the eighth voltage threshold corresponding to the fifth preset value, the seventh voltage threshold being greater than the eighth voltage threshold, and the sixth preset value being greater than the fifth preset value.

[0152] In some embodiments, the processor is further configured to determine the charge catch-up rate of the lithium iron phosphate battery based on the target SOC value and the displayed SOC value; and to correct the displayed SOC value based on the charge catch-up rate.

[0153] In some embodiments, the processor is further configured to multiply the charge catch-up rate by the SOC change in a single operating cycle of the lithium iron phosphate battery to obtain a SOC catch-up value; and to sum the SOC catch-up value and the SOC display value to obtain a corrected SOC display value.

[0154] In some embodiments, the processor is further configured to obtain the time interval between the rise of the battery voltage value of the lithium iron phosphate battery from a first value to a second value; if the time interval is greater than a preset time interval, the starting charging state is determined to be a first voltage starting charging state; if the time interval is less than or equal to the preset time interval, the starting charging state is determined to be a second voltage starting charging state.

[0155] The foregoing disclosure provides many different implementations or examples for carrying out different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described above. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed.

[0156] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0157] The above embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of protection of this application. Any non-substantial changes and substitutions made by those skilled in the art based on this application shall fall within the scope of protection claimed by this application.

Claims

1. A SOC correction method, applicable to lithium iron phosphate batteries, characterized in that, The SOC correction method includes: Based on the voltage change of the lithium iron phosphate battery, the initial charging state of the lithium iron phosphate battery is determined, wherein the initial charging state includes a first voltage initial charging state and a second voltage initial charging state, and the first voltage initial charging state and the second voltage initial charging state correspond to different initial voltage values. Based on the initial charging state and the battery voltage value of the lithium iron phosphate battery, the SOC target value of the lithium iron phosphate battery is determined; The charging catch-up rate of the lithium iron phosphate battery is determined based on the target SOC value and the displayed SOC value. The SOC display value is corrected based on the charging catch-up rate; The correction of the SOC display value based on the charging catch-up rate includes: Multiply the charging catch-up rate by the SOC change in a single operating cycle of the lithium iron phosphate battery to obtain the SOC catch-up value; The SOC catch-up value and the SOC display value are summed to obtain the corrected SOC display value.

2. The method according to claim 1, characterized in that, Determining the SOC target value of the lithium iron phosphate battery based on the initial charging state and the battery voltage value of the lithium iron phosphate battery includes: Obtain the battery voltage value of the lithium iron phosphate battery; The charging stage of the lithium iron phosphate battery is determined based on the battery voltage value and the initial charging state. The SOC target value is determined based on the battery voltage value and the corresponding charging stage.

3. The method according to claim 2, characterized in that, Determining the charging stage of the lithium iron phosphate battery based on the battery voltage value and the initial charging state includes: If the initial charging state is the first voltage initial charging state, then the charging current value of the lithium iron phosphate battery is obtained; When the battery voltage is less than a first voltage threshold and the charging current is a first current threshold, the charging stage of the lithium iron phosphate battery is determined to be the first charging stage. When the battery voltage value is within the range of the first voltage threshold and the second voltage threshold, and the charging current value is the second current threshold, the charging stage of the lithium iron phosphate battery is determined to be the second charging stage. When the battery voltage value is greater than the second voltage threshold and the charging current value is the third current threshold, the charging stage of the lithium iron phosphate battery is determined to be the third charging stage. Wherein, the second voltage threshold is greater than the first voltage threshold, the second current threshold is less than the first current threshold, and the third current threshold is less than the second current threshold.

4. The method according to claim 3, characterized in that, Determining the SOC target value of the lithium iron phosphate battery based on the initial charging state and the battery voltage value of the lithium iron phosphate battery includes: When the lithium iron phosphate battery is in the first charging stage or the second charging stage, if the battery voltage value is not greater than the third voltage threshold and the SOC display value is greater than the first preset value, the first preset value is used as the SOC target value, the third voltage threshold is less than the second voltage threshold and the third voltage threshold is greater than the first voltage threshold. When the lithium iron phosphate battery is in the second charging stage and the battery voltage value is greater than the third voltage threshold, the SOC target value is determined according to the battery voltage value and the first correspondence relationship, wherein the first correspondence relationship is determined by the third voltage threshold corresponding to the first preset value and the second voltage threshold corresponding to the second preset value, and the first preset value is less than the second preset value; When the lithium iron phosphate battery is in the third charging stage and the battery voltage value is greater than the fourth voltage threshold, the SOC target value is determined according to the battery voltage value and the second correspondence. The second correspondence is determined by the fourth voltage threshold corresponding to the third preset value and the fifth voltage threshold corresponding to the fourth preset value. The third preset value is less than the fourth preset value, the fourth voltage threshold is less than the first voltage threshold, and the fifth voltage threshold is greater than the third voltage threshold and less than the second voltage threshold.

5. The method according to claim 2, characterized in that, Determining the charging stage of the lithium iron phosphate battery based on the battery voltage value and the initial charging state includes: If the initial charging state is the second voltage initial charging state, then the charging current value of the lithium iron phosphate battery is obtained; When the battery voltage is less than the sixth voltage threshold and the charging current is the fourth current threshold, the charging stage of the lithium iron phosphate battery is determined to be the fourth charging stage. When the battery voltage value is within the range of the sixth voltage threshold and the seventh voltage threshold, and the charging current value is the fifth current threshold, the charging stage of the lithium iron phosphate battery is determined to be the fifth charging stage, wherein the sixth voltage threshold is less than the seventh voltage threshold, and the fourth current threshold is greater than the fifth current threshold.

6. The method according to claim 5, characterized in that, Determining the SOC target value of the lithium iron phosphate battery based on the initial charging state and the battery voltage value of the lithium iron phosphate battery includes: When the lithium iron phosphate battery is in the fourth charging stage and the displayed SOC value is greater than the fifth preset value, the fifth preset value is used as the target SOC value. When the lithium iron phosphate battery is in the fifth charging stage, the SOC target value is determined according to the battery voltage value and the third correspondence relationship. The third correspondence relationship is determined by the seventh voltage threshold corresponding to the sixth preset value and the eighth voltage threshold corresponding to the fifth preset value. The seventh voltage threshold is greater than the eighth voltage threshold, and the sixth preset value is greater than the fifth preset value.

7. The method according to any one of claims 1 to 6, characterized in that, Determining the initial charging state of the lithium iron phosphate battery based on the voltage change includes: The time interval during which the battery voltage of the lithium iron phosphate battery rises from a first value to a second value is obtained; If the time interval is greater than the preset time interval, then the starting charging state is determined to be the first voltage starting charging state; If the time interval is less than or equal to the preset time interval, then the starting charging state is determined to be the second voltage starting charging state.

8. An energy storage device, characterized in that, The energy storage device includes: Memory and processor; The memory is connected to the processor and is used to store programs; The processor is used to implement the steps of the SOC correction method as described in any one of claims 1-7 by running a program stored in the memory.

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