SOC estimation method, computer equipment and storage medium

Abstract

The invention relates to the technical field of batteries, particularly provides an SOC estimation method, computer equipment and a storage medium, and aims to solve the technical problem that SOC estimation corresponding to an existing method is inaccurate. In order to achieve the purpose, the SOC estimation method comprises the steps that after a battery stops being used and stands for a first preset duration, the terminal voltage of the battery is obtained; performing iterative operation according to the first hysteresis coefficient and the current hysteresis coefficient change rate to obtain a current hysteresis coefficient; and obtaining the target SOC based on the current hysteresis coefficient and the terminal voltage. Therefore, the SOC value with relatively high precision is obtained, and the estimation precision of the SOC value is improved.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and specifically provides a SOC estimation method, a computer device and a storage medium. Background Art

[0002] In the battery management system, the battery state of charge (SOC) is a very important battery parameter. SOC represents the percentage of the remaining charge of the battery pack and is used to measure the remaining available capacity of the battery pack. Accurate SOC estimation can ensure the relevant strategies of the entire vehicle, the safety of the battery, and the experience of the driver and passengers.

[0003] At present, the existing SOC estimation method mainly estimates the target SOC based on the SOC-OCV obtained under full charge or full discharge conditions. In this case, combined conditions such as charging to a certain SOC and then discharging or discharging to a certain SOC and then charging are not considered, resulting in inaccurate target SOC estimation.

[0004] Accordingly, a new SOC estimation solution is needed in the art to solve the above problems. Summary of the invention

[0005] In order to overcome the above defects, the present invention is proposed to solve or at least partially solve the above technical problems. The present invention provides a SOC estimation method, a computer device and a storage medium.

[0006] In a first aspect, the present invention provides a SOC estimation method, which includes: obtaining the terminal voltage of the battery after the battery stops being used and has been stationary for a first preset time; iteratively calculating a first hysteresis coefficient and a current hysteresis coefficient change rate to obtain a current hysteresis coefficient; and obtaining a target SOC based on the current hysteresis coefficient and the terminal voltage.

[0007] In one embodiment, before performing iterative calculation based on the first hysteresis coefficient and the current hysteresis coefficient change rate to obtain the current hysteresis coefficient, the method further includes: determining the hysteresis coefficient change rate corresponding to the first SOC and the first hysteresis coefficient as the current hysteresis coefficient change rate.

[0008] In one embodiment, the method further includes: in response to a charge-discharge commutation event, acquiring a current gain factor corresponding to the charge-discharge commutation event; and updating the current hysteresis coefficient change rate according to the current gain factor.

[0009] In one embodiment, the acquiring the current gain factor corresponding to the charge-discharge commutation event includes: for the charge-discharge commutation event, using the gain factor corresponding to the first SOC and the first hysteresis coefficient as the current gain factor.

[0010] In one embodiment, the hysteresis coefficient change rate includes a charging change rate and a discharging change rate.

[0011] In one embodiment, the correspondence between the first SOC and the first hysteresis coefficient and the hysteresis coefficient change rate is determined based on the following steps: obtaining an SOC-OCV mapping relationship based on a charge and discharge test experiment; determining the first hysteresis coefficient corresponding to each first SOC based on the SOC-OCV mapping relationship; and taking the ratio of an increment of the first hysteresis coefficient corresponding to each first SOC to an increment of the first SOC as the hysteresis coefficient change rate.

[0012] In one embodiment, the SOC-OCV mapping relationship includes a charging SOC-OCV mapping relationship and a discharging SOC-OCV mapping relationship, the charging SOC-OCV mapping relationship includes a first charging mapping relationship, an Nth charging mapping relationship and a first discharging mapping relationship, and the discharging SOC-OCV mapping relationship includes a first charging mapping relationship, a first discharging mapping relationship and an Nth discharging mapping relationship, where N is a positive integer and 1<N;

[0013] The obtaining of the charge and discharge SOC-OCV mapping relationship of the battery based on the charge and discharge test experiment includes: at a preset temperature and a preset current rate,

[0014] Discharging the battery from 100% to 0%, leaving the battery for a second preset time each time a first preset percentage of the SOC value is discharged, measuring the OCV value of the battery and recording the corresponding SOC value, and drawing a first discharge mapping relationship;

[0015] The battery is charged from 0% to 100%, and each time the SOC value of the first preset percentage is charged, the battery is left to stand for a second preset time, the OCV value of the battery is measured and the corresponding SOC value is recorded, and a first charging mapping relationship is drawn;

[0016] Discharging the battery from 100% to a second preset percentage of the SOC value, leaving the battery for a second preset time each time the first preset percentage of the SOC value is discharged, measuring the OCV value of the battery and recording the corresponding SOC value, and drawing a second discharge mapping relationship;

[0017] The battery is charged from a second preset percentage of the SOC value to 100%, and each time the SOC value is charged to the first preset percentage, the battery is left to stand for a second preset time, the OCV value of the battery is measured, the corresponding SOC value is recorded, and a second charging mapping relationship is drawn;

[0018] Discharging the battery from 100% to a third preset percentage of SOC value, leaving the battery for a second preset time each time the first preset percentage of SOC value is discharged, measuring the OCV value of the battery and recording the corresponding SOC value, and drawing a third discharge mapping relationship;

[0019] The battery is charged from a third preset percentage of the SOC value to 100%, and each time the SOC value is charged to the first preset percentage, the battery is left to stand for a second preset time, the OCV value of the battery is measured and the corresponding SOC value is recorded, and a third charging mapping relationship is drawn;

[0020] Repeat the above steps until the Nth discharge mapping relationship and the Nth charge mapping relationship are obtained.

[0021] In one embodiment, determining the first hysteresis coefficient corresponding to each first SOC based on the SOC-OCV mapping relationship includes: for each first SOC, determining the charging OCV value, discharging OCV value and hysteresis OCV value corresponding to the battery based on the charge and discharge SOC-OCV mapping relationship; calculating the difference between the hysteresis OCV value and the discharge OCV value as the first difference; calculating the difference between the charging OCV value and the discharge OCV value as the second difference; and determining the charge and discharge hysteresis coefficient corresponding to this SOC based on the ratio between the first difference and the second difference.

[0022] In a second aspect, a computer device is provided, comprising at least one processor and at least one storage device, wherein the storage device is suitable for storing a plurality of program codes, wherein the program codes are suitable for being loaded and run by the processor to execute any of the aforementioned SOC estimation methods.

[0023] In a third aspect, a computer-readable storage medium is provided, wherein a plurality of program codes are stored in the computer-readable storage medium, wherein the program codes are suitable for being loaded and run by a processor to execute any one of the aforementioned SOC estimation methods.

[0024] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0025] The SOC estimation method of the present invention includes obtaining the terminal voltage of the battery after the battery stops being used and is left to stand for a first preset time; performing an iterative operation according to the first hysteresis coefficient and the current hysteresis coefficient change rate to obtain the current hysteresis coefficient; and obtaining the target SOC based on the current hysteresis coefficient and the terminal voltage. In this way, by dynamically calculating the current hysteresis coefficient in real time during the use of the battery, the SOC value is estimated according to the current hysteresis coefficient and the terminal voltage obtained after the battery is left to stand, thereby obtaining a SOC value with higher accuracy and improving the estimation accuracy of the SOC value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In addition, similar numbers in the figures are used to represent similar components, among which:

[0027] Figure 1 is a schematic flow chart of main steps of a SOC estimation method according to an embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of a flow chart for determining a rate of change of a hysteresis coefficient in one embodiment;

[0029] Figure 3 is a schematic diagram of a charging SOC-OCV mapping relationship in an embodiment;

[0030] Figure 4 is a schematic diagram of a discharge SOC-OCV mapping relationship in an embodiment;

[0031] Figure 5 is a schematic diagram of determining a hysteresis coefficient in one embodiment;

[0032] Figure 6 is a schematic diagram of a charging rate of change in one embodiment;

[0033] Figure 7 is a schematic diagram of a discharge change rate in one embodiment;

[0034] Figure 8 is a schematic diagram of a process of iterating a hysteresis coefficient in one embodiment;

[0035] Fig. 9 is a schematic diagram of the mapping relationship between the hysteresis coefficient, the terminal voltage and the SOC in one embodiment;

[0036] Fig.10 It is a schematic diagram of the main structural block diagram of a computer device in an embodiment. DETAILED DESCRIPTION

[0037] Some embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0038] In the description of the present invention, "module" and "processor" may include hardware, software or a combination of the two. A module may include hardware circuits, various suitable sensors, communication ports, and memories, and may also include software parts, such as program codes, or a combination of software and hardware. The processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor, or any other suitable processor. The processor has data and / or signal processing functions. The processor may be implemented in software, hardware, or a combination of the two. Non-temporary computer-readable storage media include any suitable medium that can store program codes, such as a magnetic disk, a hard disk, an optical disk, a flash memory, a read-only memory, a random access memory, and the like. The term "A and / or B" means all possible combinations of A and B, such as only A, only B, or A and B. The term "at least one A or B" or "at least one of A and B" has a similar meaning to "A and / or B", and may include only A, only B, or A and B. The singular terms "one" and "the" may also include plural forms.

[0039] At present, the existing SOC estimation method mainly estimates the target SOC based on the SOC-OCV obtained under full charge or full discharge conditions. In this case, combined conditions such as charging to a certain SOC and then discharging or discharging to a certain SOC and then charging are not considered, resulting in inaccurate target SOC estimation.

[0040] To this end, the present application proposes a SOC estimation method, a computer device, and a storage medium, including: obtaining the terminal voltage of the battery after the battery stops being used and is left to stand for a first preset time; performing an iterative operation based on the first hysteresis coefficient and the current hysteresis coefficient change rate to obtain the current hysteresis coefficient; and obtaining the target SOC based on the current hysteresis coefficient and the terminal voltage. In this way, by dynamically calculating the current hysteresis coefficient in real time during the use of the battery, the SOC value is estimated based on the current hysteresis coefficient and the terminal voltage obtained after the battery is left to stand, thereby obtaining a more accurate SOC value and improving the accuracy of the SOC value estimation.

[0041] See attached Figure 1 , Figure 1 FIG. 1 is a flow chart showing the main steps of a method for estimating SOC according to an embodiment of the present invention. Figure 1 As shown, the SOC estimation method in the embodiment of the present invention mainly includes the following steps S100 to S300.

[0042] Step S100: After the battery stops being used and is left to stand for a first preset time, the terminal voltage of the battery is obtained.

[0043] The first preset time period for standing still is to eliminate the polarization voltage of the battery, eliminate the influence of polarization resistance and voltage, and facilitate accurate estimation of SOC. Optionally, the first preset time period can be 2 hours, 3 hours, etc.

[0044] Step S200: performing an iterative operation according to the first hysteresis coefficient and the current hysteresis coefficient change rate to obtain the current hysteresis coefficient.

[0045] Step S300: obtaining a target SOC based on the current hysteresis coefficient and the terminal voltage.

[0046] Based on the above steps S100 to S300, by dynamically calculating the current hysteresis coefficient in real time during the use of the battery, the SOC value is estimated based on the current hysteresis coefficient and the terminal voltage obtained after the battery is at rest, thereby obtaining a more accurate SOC value and improving the estimation accuracy of the SOC value.

[0047] In a specific embodiment, before performing iterative calculation based on the first hysteresis coefficient and the current hysteresis coefficient change rate to obtain the current hysteresis coefficient, the method also includes: determining the hysteresis coefficient change rate corresponding to the first SOC and the first hysteresis coefficient as the current hysteresis coefficient change rate.

[0048] The hysteresis coefficient can reflect the hysteresis between voltage and current during the battery charging and discharging process.

[0049] The hysteresis coefficient change rate is used to reflect the speed of change of the hysteresis coefficient.

[0050] The mapping relationship between the first SOC, the first hysteresis coefficient and the hysteresis coefficient change rate is stored in the battery management system (BMS). Before implementing the aforementioned step S200, it also includes obtaining the corresponding hysteresis coefficient change rate from the mapping relationship according to the first SOC and the first hysteresis coefficient, and using it as the current hysteresis coefficient change rate.

[0051] In this way, the current hysteresis coefficient change rate with higher accuracy is obtained according to the first SOC and the first hysteresis coefficient, which is beneficial to improving the estimation accuracy of the target SOC.

[0052] In a specific embodiment, the hysteresis coefficient change rate includes a charging change rate and a discharging change rate.

[0053] Specifically, the hysteresis coefficient change rate includes the charging change rate and the discharging change rate, wherein the charging change rate is used to characterize how fast the hysteresis coefficient changes during the charging process, and the discharging change rate is used to characterize how fast the hysteresis coefficient changes during the discharging process.

[0054] In a specific embodiment, Figure 2 As shown, the corresponding relationship between the first SOC, the first hysteresis coefficient and the hysteresis coefficient change rate is determined through the following steps S201 to S203:

[0055] Step S201: obtaining a SOC-OCV mapping relationship based on a charge and discharge test experiment.

[0056] The SOC-OCV mapping relationship is used to characterize the relationship between the SOC and OCV of the battery during the charging and discharging process.

[0057] It should be noted that the SOC-OCV mapping relationship includes a charging SOC-OCV mapping relationship and a discharging SOC-OCV mapping relationship, wherein the charging SOC-OCV mapping relationship includes a first charging mapping relationship, an Nth charging mapping relationship and a first discharging mapping relationship, and the discharging SOC-OCV mapping relationship includes a first charging mapping relationship, a first discharging mapping relationship and an Nth discharging mapping relationship. Specifically, the first charging mapping relationship is the SOC-OCV mapping relationship obtained under a fully charged condition, the first discharging mapping relationship is the SOC-OCV mapping relationship obtained under a fully discharged condition, the Nth charging mapping relationship is the SOC-OCV mapping relationship obtained under a condition of first discharging to a certain SOC and then charging, and the Nth discharging mapping relationship is the SOC-OCV mapping relationship obtained under a condition of first charging to a certain SOC and then discharging.

[0058] Exemplarily, the SOC-OCV curve may be used as an example of the above-mentioned SOC-OCV mapping relationship, but is not limited thereto.

[0059] In a specific embodiment, the SOC-OCV mapping relationship includes a charging SOC-OCV mapping relationship and a discharging SOC-OCV mapping relationship, the charging SOC-OCV mapping relationship includes a first charging mapping relationship, an Nth charging mapping relationship and a first discharging mapping relationship, and the discharging SOC-OCV mapping relationship includes a first charging mapping relationship, a first discharging mapping relationship and an Nth discharging mapping relationship, wherein N is a positive integer and 1<N; the SOC-OCV mapping relationship is obtained based on the charge and discharge test experiment, including: at a preset temperature and a preset current rate,

[0060] Discharging the battery from 100% to 0%, leaving the battery for a second preset time each time a first preset percentage of the SOC value is discharged, measuring the OCV value of the battery and recording the corresponding SOC value, and drawing a first discharge mapping relationship;

[0061] The battery is charged from 0% to 100%, and each time the SOC value of the first preset percentage is charged, the battery is left to stand for a second preset time, the OCV value of the battery is measured and the corresponding SOC value is recorded, and a first charging mapping relationship is drawn;

[0062] Discharging the battery from 100% to a second preset percentage of the SOC value, leaving the battery for a second preset time each time the first preset percentage of the SOC value is discharged, measuring the OCV value of the battery and recording the corresponding SOC value, and drawing a second discharge mapping relationship;

[0063] The battery is charged from a second preset percentage of the SOC value to 100%, and each time the SOC value is charged to the first preset percentage, the battery is left to stand for a second preset time, the OCV value of the battery is measured, the corresponding SOC value is recorded, and a second charging mapping relationship is drawn;

[0064] Discharging the battery from 100% to a third preset percentage of SOC value, leaving the battery for a second preset time each time the first preset percentage of SOC value is discharged, measuring the OCV value of the battery and recording the corresponding SOC value, and drawing a third discharge mapping relationship;

[0065] The battery is charged from a third preset percentage of the SOC value to 100%, and each time the SOC value is charged to the first preset percentage, the battery is left to stand for a second preset time, the OCV value of the battery is measured and the corresponding SOC value is recorded, and a third charging mapping relationship is drawn;

[0066] Repeat the above steps until the Nth discharge mapping relationship and the Nth charge mapping relationship are obtained.

[0067] The second preset time length for standing still is to eliminate the polarization voltage of the battery and eliminate the influence of the polarization voltage. Optionally, the second preset time length can be 2 hours, 3 hours, etc.

[0068] The preset percentage may be any value greater than 0 and less than 100%.

[0069] For example, in this embodiment, 5% is used as an example of the first preset percentage, 5% is used as an example of the second preset percentage, 10% is used as an example of the third preset percentage, ..., 95% is used as an example of the Nth preset percentage, and the charge and discharge test experiment is described in detail.

[0070] The charge and discharge test experiment refers to the pulse charge and discharge test experiment conducted on lithium batteries, which is a pulse charge and discharge test experiment conducted on lithium batteries at a constant temperature and constant current rate.

[0071] The current rate refers to the current value output by the battery when it discharges its rated capacity within a specified time, which can be used to indicate the charging rate.

[0072] Specifically, the battery is first discharged from 100% to 0%, and then left to stand for 3 hours at each 5% SOC. The OCV value of the battery is measured and the corresponding SOC value is recorded. At this time, the first discharge SOC-OCV relationship is plotted with the SOC value as the horizontal axis and the OCV value as the vertical axis.

[0073] The battery was charged from 0% to 100%, and was left standing for 3 hours each time the SOC was charged to 5%. The OCV value of the battery was measured and the corresponding SOC value was recorded. At this time, the first charging SOC-OCV relationship was plotted with the SOC value as the horizontal axis and the OCV value as the vertical axis.

[0074] The battery was discharged from 100% to 5%, and allowed to stand for 3 hours each time the SOC was 5%. The OCV value of the battery was measured and the corresponding SOC value was recorded. At this time, the SOC value was used as the horizontal axis and the OCV value was used as the vertical axis to plot the SOC-OCV relationship with 5% as the discharge endpoint, i.e. the second discharge SOC-OCV relationship.

[0075] Charge the battery from 5% to 100%, and let it stand for 3 hours every time the SOC is charged to 5%. Measure the OCV value of the battery and record the corresponding SOC value. At this time, draw a charging SOC-OCV sub-relationship with 5% as the charging starting point, with the SOC value as the horizontal axis and the OCV value as the vertical axis, i.e., the second charging SOC-OCV relationship.

[0076] The battery was discharged from 100% to 10%, and allowed to stand for 3 hours every 5% SOC. The OCV value of the battery was measured and the corresponding SOC value was recorded. At this time, a SOC-OCV sub-relationship with 10% as the discharge endpoint was plotted with the SOC value as the horizontal axis and the OCV value as the vertical axis, i.e., the third discharge SOC-OCV relationship.

[0077] Charge the battery from 10% to 100%, and let it stand for 3 hours every time the SOC is charged by 5%. Measure the OCV value of the battery and record the corresponding SOC value. At this time, draw a charging SOC-OCV sub-relationship with 10% as the charging starting point, with the SOC value as the horizontal axis and the OCV value as the vertical axis, that is, the third charging SOC-OCV relationship.

[0078] Repeat the above charging and discharging steps until the Nth discharge mapping relationship and the Nth charge mapping relationship are obtained. At this point, the SOC-OCV relationship for charging with different SOCs as the starting point and / or the SOC-OCV relationship for discharging with different SOCs as the starting point can be obtained.

[0079] Compared with the existing OCV-SOC relationship of full charge and / or full discharge, the influence of hysteresis effect on battery OCV is fully considered, so that the target SOC value estimated based on the charge and discharge SOC-OCV relationship is more accurate.

[0080] For composite negative electrode batteries, such as batteries with ternary lithium as the positive electrode and silicon-carbon composite materials as the negative electrode, the battery characteristics are difficult to capture. Therefore, in the pulse charge and discharge test, the hysteresis coefficient change rate needs to record an OCV value every 5% SOC for simulation.

[0081] For example, Figure 3 It can be used as an example of the charging SOC-OCV mapping relationship. Figure 4 This can be used as an example of a discharge SOC-OCV mapping relationship, but is not limited thereto.

[0082] Step S202: determining a first hysteresis coefficient corresponding to each first SOC based on the SOC-OCV mapping relationship.

[0083] Specifically, the SOC-OCV mapping relationship presents a mapping relationship between a plurality of first SOCs and OCVs. In this embodiment, the first hysteresis coefficient corresponding to each first SOC is determined through the SOC-OCV mapping relationship.

[0084] The first hysteresis coefficient includes a charging hysteresis coefficient and a discharging hysteresis coefficient, wherein the charging hysteresis coefficient is determined according to a charging SOC-OCV mapping relationship, and the discharging hysteresis coefficient is determined according to a discharging SOC-OCV mapping relationship.

[0085] In a specific embodiment, determining the first hysteresis coefficient corresponding to each first SOC based on the SOC-OCV mapping relationship includes: for each first SOC, determining the charging OCV value, discharging OCV value and hysteresis OCV value corresponding to the battery based on the charge and discharge SOC-OCV mapping relationship; calculating the difference between the hysteresis OCV value and the discharge OCV value as the first difference; calculating the difference between the charging OCV value and the discharge OCV value as the second difference; and determining the charge and discharge hysteresis coefficient corresponding to this SOC based on the ratio between the first difference and the second difference.

[0086] Specifically, the calculation formula of the battery charge and discharge hysteresis coefficient α can be further determined based on the charge and discharge SOC-OCV mapping relationship:

[0087]

[0088] Among them, OCV hysteresis is the hysteresis OCV value, OCV charge is the charging OCV value, OCV discharge is the discharge OCV value.

[0089] It can be seen that according to the charge and discharge SOC-OCV mapping relationship, the charge OCV value, discharge OCV value and hysteresis OCV value corresponding to the battery at each SOC value can be obtained, and then the charge hysteresis coefficient or discharge hysteresis coefficient corresponding to each SOC value can be determined.

[0090] Step S203: taking the ratio of the increment of the first hysteresis coefficient corresponding to each first SOC to the increment of the first SOC as the hysteresis coefficient change rate.

[0091] Specifically, the ratio dα / dSOC of the increase in the first hysteresis coefficient corresponding to each first SOC and the increase in the first SOC is taken as the hysteresis coefficient change rate.

[0092] The hysteresis coefficient change rate includes a charging change rate and a discharging change rate. Specifically, the ratio of the increment of the first charging hysteresis coefficient corresponding to each first SOC to the increment of the first SOC is used as the charging change rate, and / or the ratio of the increment of the first discharging hysteresis coefficient corresponding to each first SOC to the increment of the first SOC is used as the discharging change rate.

[0093] Exemplarily, the charging change rate is taken as an example of the hysteresis coefficient change rate to describe in detail the determination of the hysteresis coefficient change rate of the battery.

[0094] like Figure 5 As shown, on the SOC charging curve at point A, assuming that the SOC value at point A is 0.07 and the hysteresis voltage is 2.18V, the charging OCV value at this SOC is 2.25V, and the discharging OCV value is 2.1V, so the hysteresis coefficient at point A is (2.18-2.1) / (2.25-2.1)=0.53.

[0095] Assume that the SOC value of point B is 0.09 and the hysteresis voltage is 2.25V. The charging OCV value under this SOC is 2.3V and the discharging OCV value is 2.15V. Therefore, the hysteresis coefficient of point B is (2.25-2.15) / (2.3-2.15)=0.67.

[0096] Further, based on the derivative of the charging hysteresis coefficient with respect to the SOC value, it is determined that the charging hysteresis coefficient change rate corresponding to SOC=0.07 is (0.67-0.53) / (0.09-0.07)=0.7.

[0097] In this way, the charge change rate and discharge change rate corresponding to each first SOC can be determined and stored in the battery management system. In actual use of the battery, the current hysteresis coefficient change rate can be determined according to the actual charge and discharge conditions, the first SOC, and the hysteresis coefficient.

[0098] For example, Figure 6 As an example of the rate of change of charge, Figure 7 This can be used as an example of the discharge change rate, but is not limited to this.

[0099] The above steps S200 to S300 are further explained below.

[0100] With respect to step S200, an iterative operation is performed based on the first hysteresis coefficient and the current hysteresis coefficient change rate to obtain the current hysteresis coefficient.

[0101] The first hysteresis coefficient is a hysteresis coefficient of the battery before the iterative operation, for example, an initial hysteresis coefficient.

[0102] The formula for iterating the first hysteresis coefficient is:

[0103]

[0104] Where α is the hysteresis coefficient, which is between 0 and 1. α = 0 means it is in a fully discharged state, and α = 1 means it is in a fully charged state. k is the number of iterations, and dα / dSOC is the current hysteresis coefficient or discharge hysteresis coefficient. |dSOC k | is the absolute value of the SOC change in each operating cycle of the program, which can be obtained by ampere-hour integration calculation.

[0105] Specific as Figure 8 As shown, during the use of the battery, the initial hysteresis coefficient α_init is first obtained and used as the first hysteresis coefficient. According to the hysteresis coefficient change rate and the ampere-hour integral, the first hysteresis coefficient is iteratively calculated through the above formula (2) to obtain the current hysteresis coefficient.

[0106] In a specific embodiment, the method further includes: in response to a charge-discharge commutation event, acquiring a current gain factor corresponding to the charge-discharge commutation event; and updating the current hysteresis coefficient change rate according to the current gain factor.

[0107] In the process of calculating the current hysteresis coefficient using the current hysteresis coefficient change rate, due to the different priorities of the carbon and silicon reactions in the negative electrode material of the composite negative electrode battery during the charge and discharge conversion process, the hysteresis coefficient change rate will increase during the discharge alternation, and as the unidirectional charging and discharging proceed, the change rate gradually returns to the hysteresis coefficient change rate in normal continuous charging or discharging. To this end, this embodiment updates or compensates the current hysteresis coefficient change rate by obtaining the current gain factor related to the charge and discharge reversal event. In this way, the influence of the negative electrode material of the battery on the hysteresis coefficient change rate during the charging process is avoided, making the current hysteresis coefficient change rate more accurate and improving the calculation accuracy of the hysteresis coefficient.

[0108] In a specific implementation, the acquiring the current gain factor corresponding to the charge-discharge commutation event includes: for the charge-discharge commutation event, using the gain factor corresponding to the first SOC and the first hysteresis coefficient as the current gain factor.

[0109] The gain factor includes a charging gain factor and a discharging gain factor.

[0110] The mapping relationship between the first SOC, the first hysteresis coefficient and the gain factor is stored in the battery management system (BMS). Specifically, the corresponding gain factor can be obtained from the mapping relationship according to the first SOC and the first hysteresis coefficient, and used as the current gain factor.

[0111] The above is a further description of step S200 , and the following is a further description of step S300 .

[0112] For step S300, specifically, the battery management system stores a mapping relationship between the hysteresis coefficient, the terminal voltage and the SOC, and the target SOC value can be obtained by querying the mapping relationship based on the current hysteresis coefficient and the terminal voltage obtained in the above steps. In this way, the influence of the battery hysteresis effect on the SOC value estimation is reduced, and a target SOC value with higher accuracy is obtained.

[0113] For example, Fig. 9 The mapping relationship shown may be used as an example of the mapping relationship between the hysteresis coefficient, the terminal voltage and the preset SOC value, but is not limited thereto.

[0114] It should be clear that through offline charging and discharging experiments, five mapping relationships can be obtained, namely, the mapping relationship between the first SOC value, the first hysteresis coefficient and the charging change rate, the mapping relationship between the first SOC value, the first hysteresis coefficient and the discharge change rate, the mapping relationship between the first SOC value, the first hysteresis coefficient and the charging gain factor, the mapping relationship between the first SOC value, the first hysteresis coefficient and the discharge gain factor, and the mapping relationship between the terminal voltage, the hysteresis coefficient and the SOC (SOCmap). At the same time, these five mapping relationships are stored in the battery management system (BMS). The specific mapping relationships are as follows:

[0115] Charge change rate, input is (SOC, α).

[0116] Discharge rate of change, input is (SOC, α).

[0117] Charging gain factor, input is (SOC, α).

[0118] Discharge gain factor, input is (SOC,α).

[0119] SOCmap, input is (terminal voltage, α).

[0120] Where α is the first hysteresis coefficient.

[0121] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art can understand that in order to achieve the effects of the present invention, different steps do not have to be performed in such an order. They can be performed simultaneously (in parallel) or in other orders. These changes are within the scope of protection of the present invention.

[0122] It is understood by those skilled in the art that the present invention implements all or part of the processes in the method of the above embodiment, and can also be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium may include: any entity or device, medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory, random access memory, electric carrier signal, telecommunication signal and software distribution medium that can carry the computer program code. It should be noted that the content contained in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable storage media do not include electric carrier signals and telecommunication signals.

[0123] Furthermore, the present invention also provides a computer device. In one embodiment of the computer device according to the present invention, Fig.10 As shown, the computer device includes at least one processor 10 and at least one storage device 20, the storage device 20 can be configured to store a program for executing the SOC estimation method of the above method embodiment, and the processor 10 can be configured to execute the program in the storage device 20, which includes but is not limited to the program for executing the SOC estimation method of the above method embodiment. For ease of explanation, only the part related to the embodiment of the present invention is shown, and for specific technical details not disclosed, please refer to the method part of the embodiment of the present invention.

[0124] Exemplarily, the computer device may be a vehicle or a cloud server, etc., but is not limited thereto.

[0125] Furthermore, the present invention also provides a computer-readable storage medium. In a computer-readable storage medium embodiment according to the present invention, the computer-readable storage medium can be configured to store a program for executing the SOC estimation method of the above-mentioned method embodiment, and the program can be loaded and run by the processor to implement the above-mentioned SOC estimation method. For ease of explanation, only the parts related to the embodiment of the present invention are shown. For specific technical details not disclosed, please refer to the method part of the embodiment of the present invention. The computer-readable storage medium can be a storage device formed by various electronic devices. Optionally, the computer-readable storage medium in the embodiment of the present invention is a non-temporary computer-readable storage medium.

[0126] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A SOC estimation method, characterized in that: The method comprises: After the battery stops being used and is left to stand for a first preset time, obtaining a terminal voltage of the battery; Perform an iterative operation according to the first hysteresis coefficient and the current hysteresis coefficient change rate to obtain the current hysteresis coefficient; A target SOC is obtained based on the current hysteresis coefficient and the terminal voltage.

2. The method according to claim 1, characterized in that Before performing iterative calculation according to the first hysteresis coefficient and the current hysteresis coefficient change rate to obtain the current hysteresis coefficient, the method further includes: The hysteresis coefficient change rate corresponding to the first SOC and the first hysteresis coefficient is determined as the current hysteresis coefficient change rate.

3. The method according to claim 1, characterized in that The method further comprises: In response to a charge-discharge commutation event, obtaining a current gain factor corresponding to the charge-discharge commutation event; The current hysteresis coefficient change rate is updated according to the current gain factor.

4. The method according to claim 3, characterized in that The obtaining of the current gain factor corresponding to the charge-discharge commutation event includes: For the charge-discharge commutation event, a gain factor corresponding to the first SOC and the first hysteresis coefficient is used as the current gain factor.

5. The method according to claim 2, characterized in that: The hysteresis coefficient change rate includes a charging change rate and a discharging change rate.

6. The method according to claim 2, characterized in that The corresponding relationship between the first SOC, the first hysteresis coefficient and the hysteresis coefficient change rate is determined based on the following steps: Obtain SOC-OCV mapping relationship based on charge and discharge test experiments; Determine a first hysteresis coefficient corresponding to each first SOC based on the SOC-OCV mapping relationship; The ratio of the increment of the first hysteresis coefficient corresponding to each first SOC to the increment of the first SOC is used as the hysteresis coefficient change rate.

7. The method according to claim 6, characterized in that The SOC-OCV mapping relationship includes a charging SOC-OCV mapping relationship and a discharging SOC-OCV mapping relationship, the charging SOC-OCV mapping relationship includes a first charging mapping relationship, an Nth charging mapping relationship and a first discharging mapping relationship, and the discharging SOC-OCV mapping relationship includes a first charging mapping relationship, a first discharging mapping relationship and an Nth discharging mapping relationship, wherein N is a positive integer and 1<N; The SOC-OCV mapping relationship is obtained based on the charge and discharge test experiment, including: at a preset temperature and a preset current rate, Discharging the battery from 100% to 0%, leaving the battery for a second preset time each time a first preset percentage of the SOC value is discharged, measuring the OCV value of the battery and recording the corresponding SOC value, and drawing a first discharge mapping relationship; The battery is charged from 0% to 100%, and each time the SOC value of the first preset percentage is charged, the battery is left to stand for a second preset time, the OCV value of the battery is measured and the corresponding SOC value is recorded, and a first charging mapping relationship is drawn; Discharging the battery from 100% to a second preset percentage of the SOC value, leaving the battery for a second preset time each time the first preset percentage of the SOC value is discharged, measuring the OCV value of the battery and recording the corresponding SOC value, and drawing a second discharge mapping relationship; The battery is charged from a second preset percentage of the SOC value to 100%, and each time the SOC value is charged to the first preset percentage, the battery is left to stand for a second preset time, the OCV value of the battery is measured, the corresponding SOC value is recorded, and a second charging mapping relationship is drawn; Discharging the battery from 100% to a third preset percentage of SOC value, leaving the battery for a second preset time each time the first preset percentage of SOC value is discharged, measuring the OCV value of the battery and recording the corresponding SOC value, and drawing a third discharge mapping relationship; The battery is charged from a third preset percentage of the SOC value to 100%, and each time the SOC value is charged to the first preset percentage, the battery is left to stand for a second preset time, the OCV value of the battery is measured and the corresponding SOC value is recorded, and a third charging mapping relationship is drawn; Repeat the above steps until the Nth discharge mapping relationship and the Nth charge mapping relationship are obtained.

8. The method according to claim 6, characterized in that The determining of the first hysteresis coefficient corresponding to each first SOC based on the SOC-OCV mapping relationship includes: For each first SOC, determining a charging OCV value, a discharging OCV value and a hysteresis OCV value corresponding to the battery based on the charging and discharging SOC-OCV mapping relationship; Calculating a difference between the hysteresis OCV value and the discharge OCV value as a first difference; Calculating a difference between the charging OCV value and the discharging OCV value as a second difference; A charge and discharge hysteresis coefficient corresponding to the SOC is determined based on a ratio between the first difference and the second difference.

9. A computer device comprising at least one processor and at least one storage device, wherein the storage device is suitable for storing a plurality of program codes, characterized in that: The program code is suitable for being loaded and executed by the processor to execute the SOC estimation method according to any one of claims 1 to 8.

10. A computer-readable storage medium storing a plurality of program codes, characterized in that: The program code is suitable for being loaded and run by a processor to execute the SOC estimation method according to any one of claims 1 to 8.

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