Method and system for estimating SOC by combining absolute capacity and open circuit voltage

Abstract

The present application discloses a method and system for estimating SOC by combining absolute capacity and open-circuit voltage. The method includes: calculating the amount of electricity FCC1 charged during the process of the battery discharging fully to charging fully by the ampere-hour integration method; when the battery is static from the fully charged state and the static time reaches the preset fully charged static time, obtaining the open-circuit voltage OCV1 and temperature T1 of the battery, and by querying, obtaining the corresponding electricity value of OCV1 at the temperature of T1, denoted as the theoretical full charge capacity FCC2; calculating the deviation coefficient F_FCC based on the actual full charge capacity FCC1 and the theoretical full charge capacity FCC2; when the battery is charging and discharging, obtaining the temperature value T of the battery and the actual electricity value RCC obtained by the ampere-hour integration method; calibrating the actual electricity value RCC based on the deviation coefficient F_FCC; and obtaining the SOC value corresponding to RCC by querying based on the calibrated actual electricity value RCC and temperature T. The present application greatly improves the accuracy of SOC estimation.

Description

Technical Field

[0001] This application relates to the technical field of battery SOC estimation, and in particular to a method and system for estimating SOC by combining absolute capacity and open-circuit voltage. Background Art

[0002] Most of the existing static SOC correction methods for power lithium batteries are based on the relationship between open-circuit voltage and SOC. A corresponding relationship model between SOC and open-circuit voltage is established through experiments, that is, the relationship between relative capacity percentage and absolute voltage is established. When the battery is actually used, by collecting the real-time open-circuit voltage and temperature of the battery, the SOC value corresponding to the open-circuit voltage at the corresponding temperature can be queried.

[0003] However, although this SOC estimation method has a certain degree of typicality, it also has certain drawbacks. Taking a certain Samsung 50E battery as an example, its rated capacity is 5000 mAh. According to the corresponding relationship model between the SOC and open-circuit voltage of this battery, when the battery is charged at 25°C and fully charged, the standard open-circuit voltage of the battery is 4.161 V. However, in actual applications, due to the differences in batteries and the different actual application environments, the open-circuit voltage when the battery is actually fully charged may not necessarily reach 4.161 V, and thus it is impossible to accurately determine that when the battery SOC is 100%, the corresponding capacity is 5000 mAh. Therefore, there is a certain error in the above SOC estimation method itself when statically correcting the battery SOC, and the estimation accuracy of the battery SOC during the use of the battery is relatively low. Summary of the Invention

[0004] In order to solve the problem of low estimation accuracy of the battery SOC by the existing method, this application provides a method and system for estimating SOC by combining absolute capacity and open-circuit voltage.

[0005] In a first aspect, this application provides a method for estimating SOC by combining absolute capacity and open-circuit voltage, adopting the following technical solution: The method includes:

[0006] Calculating the actual charged amount of the battery from the fully discharged state to the fully charged state by the ampere-hour integration method, and recording it as the actual full charge amount FCC1;

[0007] When the battery is static from the fully charged state and the static time reaches the preset full charge static time, obtaining the open-circuit voltage value OCV1 and the temperature value T1 of the battery, and based on the open-circuit voltage value OCV1, the temperature value T1 and the pre-constructed battery SOC estimation model, querying the charged amount value corresponding to the open-circuit voltage value OCV1 at the temperature of T1, and recording it as the theoretical full charge amount FCC2; wherein, the battery SOC estimation model includes the corresponding relationship between the open-circuit voltage value and the charged amount value at different temperatures.

[0008] Based on the actual full charge capacity value FCC1 and the theoretical full charge capacity value FCC2, calculate the deviation coefficient F_FCC;

[0009] During the charge and discharge process of the battery, obtain the temperature value T of the battery and the actual charge capacity value RCC calculated by the ampere-hour integration method; based on the deviation coefficient F_FCC, calibrate the actual charge capacity value RCC;

[0010] Based on the calibrated actual charge capacity value RCC, the temperature T, and the battery SOC estimation model, query the SOC value corresponding to the calibrated actual charge capacity value RCC at the temperature of T; the SOC value corresponding to the calibrated actual charge capacity value RCC is the current SOC value of the battery; wherein, the battery SOC estimation model further includes the corresponding relationship between the charge capacity value and the SOC value at different temperatures.

[0011] By adopting the above technical solution, first, during the process of charging the battery to full charge after activation and full discharge, calculate the actual full charge capacity value FCC1 of the battery by the ampere-hour integration method; and according to the open circuit voltage value OCV1 and the temperature value T1 of the battery when the battery is fully charged and the static time reaches the preset full charge static time, obtain the theoretical full charge capacity value FCC2 corresponding to the full charge open circuit voltage value OCV1 by looking up in the battery SOC estimation model; according to the actual full charge capacity value FCC1 and the theoretical full charge capacity value FCC2, obtain the deviation coefficient F_FCC of the battery; then, when estimating the SOC during the charge and discharge process of the battery, on the one hand, obtain the actual charge capacity value RCC calculated by the ampere-hour integration method; on the other hand, calibrate the current actual charge capacity value RCC according to the calculated battery deviation coefficient F_FCC, and then combine the current temperature T, look up the SOC value corresponding to the calibrated actual charge capacity value RCC from the battery SOC estimation model, which is the relatively accurate battery SOC estimated according to the actual situation of the battery. The technical solution of the present application takes into account both the actual charge obtained by the ampere-hour integration method and the theoretical charge based on the open circuit voltage and temperature, combines the absolute capacity and open circuit voltage of the lithium battery, greatly improves the estimation accuracy of the battery SOC, and reduces the error.

[0012] In a specific feasible implementation, after calculating the deviation coefficient F_FCC, it further includes:

[0013] Obtain the open circuit voltage value OCV2, the temperature value T2, and the actual charge capacity value RCC_R calculated by the ampere-hour integration method of the battery in the first state; the first state indicates that the battery stops charging and discharging, and the static time reaches the preset first static time;

[0014] Based on the open circuit voltage value OCV2, the temperature value T2, and the battery SOC estimation model, query the charge value corresponding to the open circuit voltage value OCV2 at the temperature of T2, and denote it as the theoretical charge value RCC_S;

[0015] Based on the actual charge value RCC_R and the theoretical charge value RCC_S, calculate the first calibration coefficient F_RCC1, and calibrate the deviation coefficient F_FCC based on the first calibration coefficient F_RCC1;

[0016] Wherein, the first calibration coefficient F_RCC1 = RCC_R / RCC_S.

[0017] By adopting the above technical solution, when the battery stops charging and discharging and the static time reaches the preset first static time, on the one hand, according to the open circuit voltage value OCV2 and the temperature value T2 of the battery, the corresponding theoretical charge value RCC_S is found. On the other hand, the actual charge value RCC_R obtained by the ampere-hour integration method is obtained. According to the deviation between the theoretical charge value RCC_S and the actual charge value RCC_R, the first calibration coefficient F_RCC1 is obtained, so as to calibrate the deviation coefficient F_FCC. Through real-time learning and correction, the accuracy of the deviation coefficient F_FCC is guaranteed to the greatest extent, and the subsequent estimation accuracy of SOC is further improved.

[0018] In a specific feasible implementation, after calculating the deviation coefficient F_FCC, it further includes:

[0019] Obtain the open circuit voltage value OCV3 and the temperature value T3 of the battery in the second state; the second state represents that the battery voltage reaches the termination voltage and the static time reaches the preset second static time;

[0020] Based on the open circuit voltage value OCV3, the temperature value T3, and the battery SOC estimation model, query the charge value corresponding to the open circuit voltage value OCV3 at the temperature of T3, and denote it as the remaining charge value RCC_D;

[0021] Based on the actual full charge value FCC1 and the remaining charge value RCC_D, calculate the actual available charge value FCC_R;

[0022] Based on the actual full charge value FCC1 and the actual available charge value FCC_R, obtain the second calibration coefficient F_RCC2; and calibrate the deviation coefficient F_FCC based on the second calibration coefficient F_RCC2;

[0023] Wherein, the second calibration coefficient F_RCC2 = FCC_R / FCC1.

[0024] By adopting the above technical solution, when the battery voltage reaches the end voltage and the rest time reaches the preset second rest time, on the one hand, according to the open circuit voltage value OCV3 and the temperature value T3 of the battery, the corresponding remaining charge value RCC_D is found. The remaining charge value RCC_D is the electric energy that the battery cannot discharge. On the other hand, according to the difference between the actual full charge capacity value FCC1 and the remaining charge value RCC_D of the battery, the actual available charge value FCC_R of the battery can be obtained. Then, according to the actual full charge capacity value FCC1 and the actual available charge value FCC_R, the second calibration coefficient is obtained to further calibrate the deviation coefficient F_FCC, and learning is carried out according to the relevant parameters at the end of the battery charge, so as to further improve the accuracy of the deviation coefficient F_FCC and the subsequent estimation accuracy of the SOC.

[0025] In a specific feasible implementation, after obtaining the SOC value corresponding to the calibrated actual charge value RCC at temperature T, it further includes:

[0026] Obtain the open circuit voltage value OCV_X1, temperature value T_X1 of the battery at the first acquisition node and the actual charge value RCC_X1 calculated by the ampere-hour integration method; based on the open circuit voltage value OCV_X1, temperature value T_X1 and the battery SOC estimation model, query the charge value corresponding to the open circuit voltage value OCV_X1 at temperature T_X1, and record it as the theoretical charge value RCC_Y1;

[0027] Obtain the open circuit voltage value OCV_X2, temperature value T_X2 of the battery at the second acquisition node and the actual charge value RCC_X2 calculated by the ampere-hour integration method; based on the open circuit voltage value OCV_X2, temperature value T_X2 and the battery SOC estimation model, query the charge value corresponding to the open circuit voltage value OCV_X2 at temperature T_X2, and record it as the theoretical charge value RCC_Y2;

[0028] Based on the actual charge value RCC_X1 corresponding to the first acquisition node and the actual charge value RCC_X2 corresponding to the second acquisition node, obtain the actual charge difference △RCC_X; based on the theoretical charge value RCC_Y1 corresponding to the first acquisition node and the theoretical charge value RCC_Y2 corresponding to the second acquisition node, obtain the theoretical charge difference △RCC_Y;

[0029] Based on the actual charge difference △RCC_X and the theoretical charge difference △RCC_Y, calculate the battery health state SOH.

[0030] By adopting the above technical solution, the battery health is calculated by combining the actual battery capacity and the theoretical capacity corresponding to the open-circuit voltage, and the absolute capacity and open-circuit voltage of the lithium battery are combined to provide a more accurate battery health estimation result for users to refer to.

[0031] In a specific implementation manner, the battery health state SOH=(ΔRCC_X / ΔRCC_Y)*100%.

[0032] In a specific possible implementation scheme, before obtaining the actual amount of electricity charged into the battery from a fully discharged state to a fully charged state, the following steps are also included:

[0033] During the experimental phase, the battery is controlled to charge from a fully discharged state at multiple preset temperatures, and the actual amount of electricity charged from the fully discharged state to the fully charged state is calculated using the ampere-hour integration method to obtain the actual full charge value FCC_REF of the battery at each preset temperature;

[0034] At each preset temperature, the battery is controlled to start charging again from a fully discharged state, and the corresponding data between the battery power value and the SOC value is recorded;

[0035] Constructing a second SOC estimation model based on corresponding data between battery power values and SOC values at each preset temperature;

[0036] Obtaining an initial SOC estimation model; the initial SOC estimation model includes corresponding data between open circuit voltage values and SOC values at each preset temperature;

[0037] A battery SOC estimation model is constructed based on the second SOC estimation model and the initial SOC estimation model.

[0038] By adopting the above technical solution, first, the corresponding data between the battery value and the SOC value at multiple preset temperatures are obtained through experiments, and a second SOC estimation model is constructed. Then, combined with the initial SOC estimation model provided by the manufacturer, that is, the corresponding data between the open circuit voltage value and the SOC value at multiple preset temperatures, the corresponding relationship between the open circuit voltage value, the battery value and the SOC value at multiple preset temperatures can be obtained, thereby constructing a more comprehensive battery SOC estimation model.

[0039] In a specific embodiment, the deviation coefficient F_FCC=FCC1 / FCC2.

[0040] In a second aspect, the present application provides a system for estimating SOC by combining absolute capacity and open circuit voltage, applying the method for estimating SOC by combining absolute capacity and open circuit voltage in the first aspect or any one of the possible implementation schemes of the first aspect, the system including a deviation coefficient calculation module and an SOC estimation module:

[0041] The deviation coefficient calculation module is used to calculate the actual charged power value of the battery from the full discharge state to the full charge state by the ampere-hour integration method, and record it as the actual full charge power value FCC1;

[0042] The deviation coefficient calculation module is further used to, when the battery is static from the full charge state and the static time reaches the preset full charge static time, obtain the open circuit voltage value OCV1 and the temperature value T1 of the battery, and based on the open circuit voltage value OCV1, the temperature value T1 and a pre-constructed battery SOC estimation model, query the power value corresponding to the open circuit voltage value OCV1 at the temperature of T1, and record it as the theoretical full charge power value FCC2; wherein, the battery SOC estimation model includes the corresponding relationship between the open circuit voltage value and the power value at different temperatures;

[0043] The deviation coefficient calculation module is further used to calculate the deviation coefficient F_FCC based on the actual full charge power value FCC1 and the theoretical full charge power value FCC2;

[0044] The SOC estimation module is used to obtain the temperature value T of the battery and the actual power value RCC calculated by the ampere-hour integration method during the charging and discharging process of the battery;

[0045] The SOC estimation module is further used to calibrate the actual power value RCC based on the deviation coefficient F_FCC; the SOC estimation module is further used to query the SOC value corresponding to the calibrated actual power value RCC at the temperature of T based on the calibrated actual power value RCC, the temperature T and the battery SOC estimation model; the SOC value corresponding to the calibrated actual power value RCC is the current SOC value of the battery; wherein, the battery SOC estimation model further includes the corresponding relationship between the power value and the SOC value at different temperatures.

[0046] In a third aspect, the present application provides a terminal, including: a processor, a memory and a communication bus; the communication bus is used to realize the connection communication between the processor and the memory, and the processor is used to execute one or more programs stored in the memory to realize the method for estimating SOC by combining the absolute capacity and the open circuit voltage in the first aspect or any one of the feasible implementation schemes of the first aspect.

[0047] In a fourth aspect, the present application provides a computer-readable storage medium, and the computer-readable storage medium stores instructions, and when the instructions are executed, the method for estimating SOC by combining the absolute capacity and the open circuit voltage in the first aspect or any one of the feasible implementation schemes of the first aspect is executed.

[0048] In summary, the technical solution of the present application at least includes the following beneficial technical effects:

[0049] 1. First, during the process of recharging the battery after it is fully discharged and then fully charged, the actual full charge capacity value FCC1 of the battery is calculated by the ampere-hour integration method; and when the battery is fully charged and the static time reaches the preset full charge static time, based on the open circuit voltage value OCV1 and the temperature value T1 of the battery, the theoretical full charge capacity value FCC2 corresponding to the full charge open circuit voltage value OCV1 is obtained by looking up in the battery SOC estimation model; according to the actual full charge capacity value FCC1 and the theoretical full charge capacity value FCC2, the deviation coefficient F_FCC of the battery is obtained.

[0050] After that, when estimating the SOC during the charge and discharge process of the battery, on the one hand, the actual charge value RCC calculated by the ampere-hour integration method is obtained; on the other hand, according to the battery deviation coefficient F_FCC, the current actual charge value RCC is calibrated, and then combined with the current temperature T, the SOC value corresponding to the calibrated actual charge value RCC is obtained by looking up in the battery SOC estimation model, which is the relatively accurate battery SOC estimated according to the actual situation of the battery; the technical solution of the present application takes into account both the actual charge obtained by the ampere-hour integration method and the theoretical charge obtained based on the open circuit voltage and temperature, combines the absolute capacity and open circuit voltage of the lithium battery, greatly improves the estimation accuracy of the battery SOC, and reduces the error.

[0051] 2. During the actual use process, continuously learn and adjust according to the actual situation of the battery to obtain the first calibration coefficient and the second calibration coefficient, and calibrate the deviation coefficient F_FCC of the battery to comprehensively improve the estimation accuracy of the battery SOC. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is the main flow schematic diagram of the method for estimating SOC by combining absolute capacity and open circuit voltage in the embodiment of the present application;

[0053] Figure 2 is the flow schematic diagram of calibrating the deviation coefficient according to the first calibration coefficient in the embodiment of the present application;

[0054] Figure 3 is the flow schematic diagram of calibrating the deviation coefficient according to the second calibration coefficient in the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] To make the objectives, technical solutions, and advantages of the present application clearer, the following will further describe the embodiments of the present application in detail with reference to the accompanying drawings.

[0056] The embodiment of the present application provides a method for estimating SOC by combining absolute capacity and open circuit voltage. Referring to Figure 1 , the method includes the following steps:

[0057] S1. Calculate the actual charge amount that the battery has charged from the fully discharged state to the fully charged state by the ampere-hour integration method, and record it as the actual full charge amount FCC1. Preferably, the actual charge amount that the battery has charged for the first time from the activated fully discharged state to the fully charged state can be calculated by the ampere-hour integration method.

[0058] Those skilled in the art can understand that based on the real-time collected current value, the actual charge amount that the battery has charged during the process from the fully discharged state to the fully charged state can be calculated by the ampere-hour integration method, and this application will not elaborate further here.

[0059] S2. When the battery is static from the fully charged state and the static time reaches the preset full charge static time, obtain the open circuit voltage value OCV1 and the temperature value T1 of the battery, and based on the open circuit voltage value OCV1, the temperature value T1 and the pre-constructed battery SOC estimation model, query the charge amount corresponding to the open circuit voltage value OCV1 at the temperature of T1, and record it as the theoretical full charge amount FCC2; wherein, the battery SOC estimation model includes the corresponding relationship between the open circuit voltage value and the charge amount at different temperatures.

[0060] Preferably, after the battery is fully charged and the static time reaches the preset full charge static time, at this time the open circuit voltage of the battery tends to be stable, and then the open circuit voltage value OCV1 is collected. The full charge static time is, for example, 3 hours.

[0061] S3. Calculate the deviation coefficient F_FCC based on the actual full charge amount FCC1 and the theoretical full charge amount FCC2.

[0062] Among them, the deviation coefficient F_FCC = FCC1 / FCC2.

[0063] S4. During the charge and discharge process of the battery, obtain the temperature value T of the battery and the actual charge amount RCC calculated by the ampere-hour integration method.

[0064] Specifically, during the charge and discharge process of the battery, the charge and discharge current value can be recorded in real time through software, and the actual charge and discharge amount of the battery can be calculated in real time by the ampere-hour integration method, and the actual charge amount of the battery can be obtained in real time.

[0065] S5. Calibrate the actual charge amount RCC based on the deviation coefficient F_FCC, and then obtain the calibrated actual charge amount RCC.

[0066] Among them, the calibrated actual charge amount RCC = F_FCC * the actual charge amount RCC before calibration.

[0067] S6. Based on the calibrated actual charge value RCC, the temperature T, and the battery SOC estimation model, query the SOC value corresponding to the calibrated actual charge value RCC at the temperature T; the SOC value corresponding to the calibrated actual charge value RCC is the current SOC value of the battery; wherein, the battery SOC estimation model further includes the corresponding relationship between the charge value and the SOC value at different temperatures.

[0068] Therefore, in the technical solution of the present application, for this battery, through steps S1 - S3, firstly, during the process of fully discharging and then fully charging the battery after activation, the actual full charge capacity value FCC1 of the battery is calculated by the ampere - hour integration method; and according to the open - circuit voltage value OCV1 and the temperature value T1 of the battery when it is fully charged and the static time reaches the preset full - charge static time, the theoretical full charge capacity value FCC2 corresponding to the full - charge open - circuit voltage value OCV1 is obtained by looking up in the battery SOC estimation model; according to the actual full charge capacity value FCC1 and the theoretical full charge capacity value FCC2, the deviation coefficient F_FCC of this battery is obtained.

[0069] After that, through steps S4 - S6, when estimating the SOC during the charging and discharging process of the battery, on the one hand, the actual charge value RCC calculated by the ampere - hour integration method is obtained; on the other hand, according to the calculated battery deviation coefficient F_FCC, the current actual charge value RCC is calibrated, and then combined with the current temperature T, the SOC value corresponding to the calibrated actual charge value RCC is obtained by looking up in the battery SOC estimation model, which is the relatively accurate battery SOC estimated according to the actual situation of this battery. The technical solution of the present application takes into account both the actual charge obtained by the ampere - hour integration method and the theoretical charge based on the open - circuit voltage and temperature, combines the absolute capacity and open - circuit voltage of the lithium battery, greatly improves the estimation accuracy of the battery SOC, and reduces the error.

[0070] In a possible implementation manner, referring to Figure 2 , after step S3 of calculating the deviation coefficient F_FCC, the following steps are further included:

[0071] A1. Obtain the open - circuit voltage value OCV2, the temperature value T2, and the actual charge value RCC_R calculated by the ampere - hour integration method of the battery in the first state; the first state indicates that the battery stops charging and discharging, and the static time reaches the preset first static time; the first static time is, for example, 3 hours.

[0072] Similarly, the charge - discharge current value of the battery can be recorded in real - time by software, and the cumulative actual charge - discharge capacity of the battery can be calculated by the ampere - hour integration method, so as to obtain the actual charge value of the battery in real - time.

[0073] A2. Based on the open-circuit voltage value OCV2, the temperature value T2, and the battery SOC estimation model, query the power value corresponding to the open-circuit voltage value OCV2 at the temperature of T2, and denote it as the theoretical power value RCC_S.

[0074] A3. Based on the actual power value RCC_R and the theoretical power value RCC_S, calculate the first calibration coefficient F_RCC1, and calibrate the deviation coefficient F_FCC based on the first calibration coefficient F_RCC1;

[0075] Among them, the first calibration coefficient F_RCC1 = RCC_R / RCC_S, and the calibrated deviation coefficient F_FCC = the deviation coefficient F_FCC before calibration * the first calibration coefficient F_RCC1.

[0076] Through the above steps A1 - A3, when the battery stops charging and discharging and the static time reaches the preset first static time, on the one hand, according to the open-circuit voltage value OCV2 and the temperature value T2 of the battery, find the corresponding theoretical power value RCC_S. On the other hand, calculate the actual power value RCC_R of the battery through the ampere-hour integration method. According to the deviation between the theoretical power value RCC_S and the actual power value RCC_R, obtain the first calibration coefficient F_RCC1, so as to calibrate the deviation coefficient F_FCC. Through real-time learning and correction, the accuracy of the deviation coefficient F_FCC is guaranteed to the greatest extent, and the estimation accuracy of the subsequent SOC is further improved.

[0077] In a possible implementation manner, referring to Figure 3 Step S3, after calculating the deviation coefficient F_FCC, the following steps are further included:

[0078] B1. Obtain the open-circuit voltage value OCV3 and the temperature value T3 of the battery in the second state; the second state indicates that the battery voltage reaches the termination voltage and the static time reaches the preset second static time; the second static time is, for example, 3 hours; the battery voltage reaching the termination voltage indicates that the battery has no electric energy to output, and the charge of the battery can no longer supply the electric energy required for the operation of electric vehicles and other electrical equipment.

[0079] B2. Based on the open-circuit voltage value OCV3, the temperature value T3, and the battery SOC estimation model, query the power value corresponding to the open-circuit voltage value OCV3 at the temperature of T3, and denote it as the remaining power value RCC_D.

[0080] B3. Based on the actual full charge capacity value FCC1 and the remaining power value RCC_D, calculate the actual available power value FCC_R; where, the actual available power value FCC_R = FCC1 - RCC_D;

[0081] B4. Based on the actual full charge capacity value FCC1 and the actual available charge capacity value FCC_R, obtain the second calibration coefficient F_RCC2; and calibrate the deviation coefficient F_FCC based on the second calibration coefficient F_RCC2;

[0082] wherein, the second calibration coefficient F_RCC2 = FCC_R / FCC1;

[0083] The corrected deviation coefficient F_FCC = the deviation coefficient F_FCC before correction * F_RCC2.

[0084] Through the above steps B1 - B3, when the battery voltage reaches the end voltage and the static time reaches the preset second static time, on the one hand, according to the open - circuit voltage value OCV3 and the temperature value T3 of the battery, find the corresponding remaining charge capacity value RCC_D, and the remaining charge capacity value RCC_D is the electric energy that the battery cannot discharge; on the other hand, according to the difference between the actual full charge capacity value FCC1 of the battery and the remaining charge capacity value RCC_D, the actual available charge capacity value FCC_R of the battery can be obtained, and then according to the actual full charge capacity value FCC1 and the actual available charge capacity value FCC_R, obtain the second calibration coefficient to further calibrate the deviation coefficient F_FCC, and learn according to the relevant parameters when the battery charge ends, further improving the accuracy of the deviation coefficient F_FCC and the subsequent estimation accuracy of SOC.

[0085] In a possible implementation manner, after step S6, obtaining the SOC value corresponding to the calibrated actual charge capacity RCC at temperature T, the following steps are further included:

[0086] S7. Obtain the open - circuit voltage value OCV_X1, the temperature value T_X1 of the battery at the first acquisition node, and the actual charge capacity value RCC_X1 calculated by the ampere - hour integration method;

[0087] Based on the open - circuit voltage value OCV_X1, the temperature value T_X1 and the battery SOC estimation model, query the charge capacity value corresponding to the open - circuit voltage value OCV_X1 at temperature T_X1, and denote it as the theoretical charge capacity value RCC_Y1;

[0088] S8. Obtain the open - circuit voltage value OCV_X2, the temperature value T_X2 of the battery at the second acquisition node, and the actual charge capacity value RCC_X2 calculated by the ampere - hour integration method;

[0089] Based on the open - circuit voltage value OCV_X2, the temperature value T_X2 and the battery SOC estimation model, query the charge capacity value corresponding to the open - circuit voltage value OCV_X2 at temperature T_X2, and denote it as the theoretical charge capacity value RCC_Y2.

[0090] S9. Obtain the actual power difference ΔRCC_X based on the actual power value RCC_X1 corresponding to the first acquisition node and the actual power value RCC_X2 corresponding to the second acquisition node;

[0091] Obtain the theoretical power difference ΔRCC_Y based on the theoretical power value RCC_Y1 corresponding to the first acquisition node and the theoretical power value RCC_Y2 corresponding to the second acquisition node.

[0092] S10. Calculate the state of health (SOH) of the battery based on the actual power difference ΔRCC_X and the theoretical power difference ΔRCC_Y;

[0093] Wherein, the state of health (SOH) of the battery = (ΔRCC_X / ΔRCC_Y) * 100%.

[0094] Those skilled in the art can set the first acquisition node and the second acquisition node by themselves. Exemplarily, by setting a fixed acquisition time interval, such as 2 hours, 5 hours, one day, etc., after the first acquisition, after the acquisition time interval, the second acquisition is performed; or setting a fixed time as the first acquisition node and the second acquisition node, such as performing the first acquisition at 10 am and the second acquisition at 6 pm, etc. The present application does not limit this.

[0095] Through the above steps S7 - S10, the technical solution of the present application can also combine the actual power of the battery and the theoretical power corresponding to the open - circuit voltage, combine the absolute capacity and open - circuit voltage of the lithium battery, calculate the state of health of the battery, provide a more accurate estimation result of the state of health of the battery, and provide a reference for users.

[0096] In a possible implementation manner, before step S1, obtaining the power value actually charged into the battery from the fully - discharged state to the fully - charged state, the following steps are further included:

[0097] C1. In the experimental stage, control the battery to start charging from the fully - discharged state at multiple preset temperatures, and calculate the power value actually charged into the battery from the fully - discharged state to the fully - charged state by the ampere - hour integration method, so as to obtain the actual full - charge power value FCC_REF of the battery at each preset temperature.

[0098] C2. At each preset temperature, respectively control the battery to start charging from the fully - discharged state again, and record the corresponding data between the power value and the state of charge (SOC) value of the battery;

[0099] Among them, recording the corresponding data between the power value and the SOC value of the battery specifically includes: when the battery is in the fully - discharged state, both the power value and the SOC value are recorded as 0, and every time of power is charged into the battery, the battery power value is increased by the SOC value is increased by Until the battery reaches the fully charged state, record the battery charge value and the SOC value, and obtain the corresponding data between the battery charge value and the SOC value at each preset temperature, where n is a positive integer.

[0100] C3. Based on the corresponding data between the charge value and the SOC value at each preset temperature, construct a second SOC estimation model.

[0101] It can be seen that the more preset temperature values and the larger the value of n, the more data in the second SOC estimation model, and the higher the accuracy in subsequent estimation of the battery SOC. However, relatively speaking, the workload will also increase. Therefore, those skilled in the art can set which groups of temperature value data need to be collected and the value of n according to actual needs. Exemplarily, the preset temperatures include -20°C, -10°C, 0°C, 10°C, 25°C, 45°C, 55°C, and n is 20, that is, the charging process of the battery is divided into 20 times, and each time the charged electricity, the battery charge value is increased by the SOC value is increased by That is, each 5% change in SOC is a node, and the corresponding data of 20 groups of battery charge values and SOC values at the preset temperature are obtained, as shown in Table 1. Only part of the data is shown in Table 1.

[0102] Table 1 Second SOC Estimation Model

[0103]

[0104] C4. Obtain an initial SOC estimation model; the initial SOC estimation model includes the corresponding data between the open-circuit voltage value and the SOC value at each preset temperature.

[0105] The initial SOC estimation model is generally provided by the battery manufacturer. Exemplarily, as shown in Table 2, it is the initial SOC estimation model provided by a certain battery manufacturer. This model includes the corresponding data between the open-circuit voltage value and the SOC value at -20°C, -10°C, 0°C, 10°C, 25°C, 45°C, 55°C. Only part of the data is shown in Table 2.

[0106] Table 2 Initial SOC Estimation Model

[0107] -20℃ -10℃ …… 45℃ 55℃ SOC Open circuit voltage value Open circuit voltage value Open circuit voltage value Open circuit voltage value Open circuit voltage value 100％ 4.149V 4.156V …… 4.158V 4.150V 95％ 4.087V 4.091V …… 4.096V 4.094V 90％ …… …… …… …… …… 85％ …… …… …… …… …… …… …… …… …… …… …… 10％ …… …… …… …… …… 5％ …… …… …… …… …… 0 …… …… …… …… ……

[0108] C5. Based on the second SOC estimation model and the initial SOC estimation model, construct a battery SOC estimation model.

[0109] Among them, step C5 specifically includes:

[0110] Based on the initial SOC estimation model and the second SOC estimation model, corresponding data among the open-circuit voltage value, the charge quantity value, and the SOC value at each preset temperature are obtained;

[0111] Based on the corresponding data among the open-circuit voltage value, the charge quantity value, and the SOC value at each preset temperature, through data linearization processing and fitting, the corresponding relationship among the open-circuit voltage value, the charge quantity value, and the SOC value at different temperatures is obtained; that is, based on the corresponding open-circuit voltage value, charge quantity value, and SOC value at adjacent preset temperatures, through data linearization processing and fitting, the corresponding data among the open-circuit voltage value, the charge quantity value, and the SOC value at any temperature value between adjacent temperatures can be obtained;

[0112] Based on the corresponding relationship among the open-circuit voltage value, the charge quantity value, and the SOC value at different temperatures, a battery SOC estimation model is constructed.

[0113] Therefore, through steps C1 - C5, first, the corresponding data between the charge quantity value and the SOC value at multiple preset temperatures are obtained through experiments to construct the second SOC estimation model, and then combined with the initial SOC estimation model provided by the manufacturer, that is, the corresponding data between the open-circuit voltage value and the SOC value at multiple preset temperatures, the corresponding data among the open-circuit voltage value, the charge quantity value, and the SOC value at multiple preset temperatures can be obtained. Due to limited data, through data linearization processing and fitting, the corresponding data among the open-circuit voltage value, the charge quantity value, and the SOC value within the full temperature range can be obtained, thereby constructing a more comprehensive battery SOC estimation model.

[0114] In a possible implementation manner, in step C5, during the data linearization processing and fitting process, if the linearization degree of the SOC decay between two adjacent preset temperature values of the battery does not meet the requirements, a supplementary temperature tx℃ can be selected between these two adjacent preset temperatures t1℃ and t2℃; t1℃ < tx℃ < t2℃;

[0115] And at tx℃, control the battery to start charging from the fully discharged state, record both the charge quantity value and the SOC value of the battery in the fully discharged state as 0, and every time the charge quantity of is charged, increase the charge quantity value of the battery by and increase the SOC value by

[0116] until the battery reaches the fully charged state, and the corresponding data between the charge quantity value and the SOC value at tx℃ are obtained;

[0117] Finally, the corresponding data between tx °C, the battery charge value and the SOC value, and the corresponding data between the open-circuit voltage value and the SOC value are filled into the battery SOC estimation model.

[0118] It should be noted that in the embodiments of the present application, to obtain the actual battery charge value, the ampere-hour integration method can be adopted to calculate the actual battery charge value.

[0119] The embodiments of the present application provide a system for estimating SOC by combining the absolute capacity and the open-circuit voltage. Applying the method for estimating SOC by combining the absolute capacity and the open-circuit voltage described in the above embodiments, the system includes a deviation coefficient calculation module and an SOC estimation module:

[0120] The deviation coefficient calculation module is used to calculate the actual charge value of the battery from the fully discharged state to the fully charged state by the ampere-hour integration method, and record it as the actual full charge value FCC1;

[0121] The deviation coefficient calculation module is further used to, when the battery is static from the fully charged state and the static time reaches the preset fully charged static time, obtain the open-circuit voltage value OCV1 and the temperature value T1 of the battery, and based on the open-circuit voltage value OCV1, the temperature value T1 and the pre-constructed battery SOC estimation model, query the charge value corresponding to the open-circuit voltage value OCV1 at the temperature of T1, and record it as the theoretical full charge value FCC2; wherein, the battery SOC estimation model includes the corresponding relationship between the open-circuit voltage value and the charge value at different temperatures;

[0122] The deviation coefficient calculation module is further used to calculate the deviation coefficient F_FCC based on the actual full charge value FCC1 and the theoretical full charge value FCC2;

[0123] The SOC estimation module is used to obtain the temperature value T of the battery and the actual charge value RCC calculated by the ampere-hour integration method during the charging and discharging process of the battery;

[0124] The SOC estimation module is further used to calibrate the actual charge value RCC based on the deviation coefficient F_FCC; the SOC estimation module is further used to query the SOC value corresponding to the calibrated actual charge value RCC at the temperature of T based on the calibrated actual charge value RCC, the temperature T and the battery SOC estimation model; the SOC value corresponding to the calibrated actual charge value RCC is the current SOC value of the battery; wherein, the battery SOC estimation model further includes the corresponding relationship between the charge value and the SOC value at different temperatures.

[0125] An embodiment of the present application provides a terminal, including: a processor, a memory, and a communication bus; the communication bus is used to implement connection communication between the processor and the memory, and the processor is used to execute one or more programs stored in the memory to implement the method for estimating the SOC by combining the absolute capacity and the open-circuit voltage described in the above embodiment.

[0126] An embodiment of the present application provides a computer-readable storage medium, and the computer-readable storage medium stores instructions, which when executed, execute the method for estimating the SOC by combining the absolute capacity and the open-circuit voltage described in the above embodiment.

[0127] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A method for estimating SOC by combining absolute capacity and open circuit voltage, characterized in that, Including: Calculating the actual charge amount that the battery is charged from the fully discharged state to the fully charged state by the ampere-hour integration method, and recording it as the actual full charge amount FCC1; When the battery is static from the fully charged state and the static time reaches the preset full charge static time, obtaining the open circuit voltage value OCV1 and the temperature value T1 of the battery, and based on the open circuit voltage value OCV1, the temperature value T1 and the pre-constructed battery SOC estimation model, querying the charge amount corresponding to the open circuit voltage value OCV1 at the temperature of T1, and recording it as the theoretical full charge amount FCC2; wherein, the battery SOC estimation model includes the corresponding relationship between the open circuit voltage value and the charge amount at different temperatures; based on the actual full charge amount FCC1 and the theoretical full charge amount FCC2, calculating the deviation coefficient F_FCC; during the charge and discharge process of the battery, obtaining the temperature value T of the battery and the actual charge amount RCC calculated by the ampere-hour integration method; based on the deviation coefficient F_FCC, calibrating the actual charge amount RCC; wherein, the calibrated actual charge amount RCC = F_FCC * the actual charge amount RCC before calibration; Based on the calibrated actual charge amount RCC, the temperature T and the battery SOC estimation model, querying the SOC value corresponding to the calibrated actual charge amount RCC at the temperature of T; the SOC value corresponding to the calibrated actual charge amount RCC is the current SOC value of the battery; wherein, the battery SOC estimation model further includes the corresponding relationship between the charge amount and the SOC value at different temperatures; Wherein, after calculating the deviation coefficient F_FCC, it further includes: Obtaining the open circuit voltage value OCV3 and the temperature value T3 of the battery in the second state; the second state represents that the battery voltage reaches the termination voltage and the static time reaches the preset second static time; Based on the open circuit voltage value OCV3, the temperature value T3 and the battery SOC estimation model, querying the charge amount corresponding to the open circuit voltage value OCV3 at the temperature of T3, and recording it as the remaining charge amount RCC_D; Based on the actual full charge amount FCC1 and the remaining charge amount RCC_D, calculating the actual available charge amount FCC_R; Based on the actual full charge amount FCC1 and the actual available charge amount FCC_R, obtaining the second calibration coefficient F_RCC2, and calibrating the deviation coefficient F_FCC based on the second calibration coefficient F_RCC2.

2. The method for estimating SOC by combining absolute capacity and open circuit voltage according to claim 1, characterized in that, After calculating the deviation coefficient F_FCC, it further includes: Obtaining the open circuit voltage value OCV2, the temperature value T2 of the battery in the first state, and the actual charge amount RCC_R calculated by the ampere-hour integration method; the first state represents that the battery stops charging and discharging and the static time reaches the preset first static time; based on the open circuit voltage value OCV2, the temperature value T2 and the battery SOC estimation model, querying the charge amount corresponding to the open circuit voltage value OCV Based on the actual power value RCC_R and the theoretical power value RCC_S, calculate the first calibration coefficient F_RCC1, and calibrate the deviation coefficient F_FCC based on the first calibration coefficient F_RCC1; Wherein, the first calibration coefficient F_RCC1 = RCC_R / RCC_S.

3. The method for estimating SOC by combining absolute capacity and open-circuit voltage according to claim 1, characterized in that The second calibration coefficient F_RCC2 = FCC_R / FCC1.

4. The method for estimating SOC by combining absolute capacity and open circuit voltage according to claim 1, characterized in that After obtaining the SOC value corresponding to the calibrated actual power value RCC at temperature T, it further includes: Obtain the open-circuit voltage value OCV_X1, temperature value T_X1 of the battery at the first acquisition node, and the actual power value RCC_X1 calculated by the ampere-hour integration method; based on the open-circuit voltage value OCV_X1, temperature value T_X1 and the battery SOC estimation model, query the power value corresponding to the open-circuit voltage value OCV_X1 at temperature T_X1, and record it as the theoretical power value RCC_Y1; obtain the open-circuit voltage value OCV_X2, temperature value T_X2 of the battery at the second acquisition node, and the actual power value RCC_X2 calculated by the ampere-hour integration method; based on the open-circuit voltage value OCV_X2, temperature value T_X2 and the battery SOC estimation model, query the power value corresponding to the open-circuit voltage value OCV_X2 at temperature T_X2, and record it as the theoretical power value RCC_Y2; based on the actual power value RCC_X1 corresponding to the first acquisition node and the actual power value RCC_X2 corresponding to the second acquisition node, obtain the actual power difference △RCC_X; based on the theoretical power value RCC_Y1 corresponding to the first acquisition node and the theoretical power value RCC_Y2 corresponding to the second acquisition node, obtain the theoretical power difference △RCC_Y; Based on the actual power difference △RCC_X and the theoretical power difference △RCC_Y, calculate the battery health SOH.

5. The method for estimating SOC by combining absolute capacity and open circuit voltage according to claim 4, characterized in that, The battery health SOH = (△RCC_X / △RCC_Y) * 100%.

6. The method for estimating SOC by combining absolute capacity and open-circuit voltage according to claim 1, characterized in that Before obtaining the power value actually charged by the battery from the fully discharged state to the fully charged state, the following steps are further included: In the experimental stage, control the battery to start charging from the fully discharged state at multiple preset temperatures, and calculate the power value actually charged by the battery from the fully discharged state to the fully charged state by the ampere-hour integration method to obtain the actual full charge power value FCC_REF of the battery at each preset temperature; At each preset temperature, respectively control the battery to start charging from the fully discharged state again, and record the corresponding data between the power value and the SOC value of the battery; Based on the corresponding data between the power value and the SOC value at each preset temperature, construct a second SOC estimation model; Obtain the initial SOC estimation model; the initial SOC estimation model includes the corresponding data between the open-circuit voltage value and the SOC value at each preset temperature; Based on the second SOC estimation model and the initial SOC estimation model, construct a battery SOC estimation model.

7. The method for estimating SOC by combining absolute capacity and open circuit voltage according to claim 1, characterized in that The deviation coefficient F_FCC = FCC1 / FCC2.

8. A system for estimating SOC by combining absolute capacity and open circuit voltage, characterized in that, It includes a deviation coefficient calculation module and an SOC estimation module: The deviation coefficient calculation module is used to calculate the actual charge amount of the battery from the full discharge state to the full charge state by the ampere-hour integration method, and record it as the actual full charge amount FCC1; The deviation coefficient calculation module is also used to obtain the open circuit voltage value OCV1 and the temperature value T1 of the battery when the battery stands still from the full charge state and the standing time reaches the preset full charge standing time, and based on the open circuit voltage value OCV1, the temperature value T1 and the pre-constructed battery SOC estimation model, query the charge amount corresponding to the open circuit voltage value OCV1 at the temperature of T1, and record it as the theoretical full charge amount FCC2; wherein, the battery SOC estimation model includes the corresponding relationship between the open circuit voltage value and the charge amount at different temperatures; The deviation coefficient calculation module is also used to calculate the deviation coefficient F_FCC based on the actual full charge amount FCC1 and the theoretical full charge amount FCC2; The SOC estimation module is used to obtain the temperature value T of the battery and the actual charge amount RCC calculated by the ampere-hour integration method during the charge and discharge process of the battery; The SOC estimation module is also used to calibrate the actual charge amount RCC based on the deviation coefficient F_FCC; wherein, the calibrated actual charge amount RCC = F_FCC * the actual charge amount RCC before calibration; The SOC estimation module is also used to query the SOC value corresponding to the calibrated actual charge amount RCC at the temperature of T based on the calibrated actual charge amount RCC, the temperature T and the battery SOC estimation model; the SOC value corresponding to the calibrated actual charge amount RCC is the current SOC value of the battery; wherein, the battery SOC estimation model also includes the corresponding relationship between the charge amount and the SOC value at different temperatures; Wherein, after calculating the deviation coefficient F_FCC, the deviation coefficient calculation module is also used to execute: Obtain the open circuit voltage value OCV3 and the temperature value T3 of the battery in the second state; the second state indicates that the battery voltage reaches the termination voltage and the standing time reaches the preset second standing time; Based on the open circuit voltage value OCV3, the temperature value T3 and the battery SOC estimation model, query the charge amount corresponding to the open circuit voltage value OCV3 at the temperature of T3, and record it as the remaining charge amount RCC_D; Calculate the actual available charge amount FCC_R based on the actual full charge amount FCC1 and the remaining charge amount RCC_D; Obtain the second calibration coefficient F_RCC2 based on the actual full charge amount FCC1 and the actual available charge amount FCC_R, and calibrate the deviation coefficient F_FCC based on the second calibration coefficient F_RCC2.

9. A terminal, characterized in that, It includes: A processor, a memory, and a communication bus; the communication bus is used to implement connection communication between the processor and the memory, and the processor is used to execute one or more programs stored in the memory to implement the method for estimating the SOC by combining the absolute capacity and the open-circuit voltage as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores instructions that, when executed, perform the method for estimating the SOC by combining the absolute capacity and the open-circuit voltage as described in any one of claims 1-7.

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