SOH calibration method, device, equipment and medium

Abstract

The invention discloses an SOH calibration method, device, equipment and medium, which are applied to the field of energy storage, and the method comprises the steps: monitoring the open-circuit voltage and current of a battery, recording the current time as the first time when the open-circuit voltage reaches a full-charge linear interval or a full-discharge linear interval, and obtaining the chargeable and dischargeable capacity of the battery at the current temperature; based on the open-circuit voltage corresponding to the first time, determining the current state of charge of the battery; based on the chargeable and dischargeable capacity and the charge state, the theoretical chargeable and dischargeable capacity of the battery is determined; when the open-circuit voltage reaches a full charge state or a full discharge state, recording the current time as second time, and performing time integration on the current of the battery from the first time to the second time to obtain the actual charge and discharge quantity of the battery; and determining the first SOH of the battery according to the actual charge and discharge quantity and the theoretical chargeable and dischargeable quantity. Therefore, the SOH of the current energy storage system can be quickly calibrated.

Description

Technical Field

[0001] The present invention relates to the field of energy storage, and in particular to a SOH calibration method, device, equipment and medium. Background Art

[0002] As a core component in industrial and commercial energy storage systems, the performance of batteries directly affects the efficiency, reliability and safety of energy storage systems. The battery's SOH (State Of Health) refers to the battery's health status, which can reflect the degree of performance degradation of the battery relative to its initial state.

[0003] In the prior art, the SOH module calculation method for industrial and commercial energy storage is usually based on the number of charge and discharge cycles and calendar life of the energy storage system. However, since this calculation method is limited by factors such as temperature, DOD (Depth of discharge), and rate, it is difficult to quickly and effectively estimate the SOH of the current system.

[0004] Therefore, how to quickly calibrate the SOH of the current energy storage system is an urgent problem to be solved. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a SOH calibration method for quickly calibrating the SOH of the current energy storage system. The specific scheme is as follows:

[0006] In a first aspect, the present application provides a SOH calibration method, comprising:

[0007] Monitor the open circuit voltage and current of the battery, and when the open circuit voltage reaches the full charge linear interval or the full discharge linear interval, record the current time as the first time, and obtain the chargeable and dischargeable capacity of the battery at the current temperature;

[0008] determining a current state of charge of the battery based on the open circuit voltage corresponding to the first time;

[0009] Determining a theoretical chargeable and dischargeable amount of the battery based on the chargeable and dischargeable capacity and the state of charge;

[0010] When the open circuit voltage reaches a fully charged state or a fully discharged state, the current time is recorded as a second time, and the current of the battery from the first time to the second time is time-integrated to obtain an actual charge and discharge amount of the battery;

[0011] A first SOH of the battery is determined according to the actual charge and discharge amount and the theoretical charge and discharge amount.

[0012] Optionally, also include:

[0013] Determining a second SOH of the battery through a cycle-SOH table based on the actual charge and discharge amount and the nominal capacity of the battery;

[0014] The storage time of the battery is obtained, and based on the storage time, a third SOH of the battery is determined by using a decay table corresponding to the battery.

[0015] Optionally, the calculating of the current performs time calculation from the first time to the second time to obtain the actual charge and discharge amount of the battery, further comprising:

[0016] Each time charging and discharging is successful, the number of successful charging and discharging of the battery is increased by 1 to determine the total number of successful charging and discharging of the battery in one day;

[0017] Determining a calibration coefficient based on the total number of successful charge and discharge times;

[0018] Determine a first weighting coefficient and a second weighting coefficient based on the calibration coefficient and a preset constraint condition; wherein the sum of the first weighting coefficient, the second weighting coefficient and the calibration coefficient is 1;

[0019] Determine that the first weighting coefficient, the second weighting coefficient, and the calibration coefficient are weighting coefficients corresponding to the second SOH, the third SOH, and the comprehensive SOH in sequence; wherein the comprehensive SOH is obtained by combining all the first SOHs calculated within one day;

[0020] Based on the weighting coefficient, the second SOH, the third SOH and the comprehensive SOH are weighted and calculated to determine the overall SOH of the battery.

[0021] Optionally, determining the first weighting coefficient and the second weighting coefficient based on the calibration coefficient and a preset constraint condition includes:

[0022] Determining whether the calibration coefficient is greater than a preset threshold;

[0023] If it is greater than, the second weighting coefficient is determined to be 0.02;

[0024] If it is less than, the second weighting coefficient is determined to be 0.1;

[0025] A first difference between the sum of the calibration coefficient and the second weighting coefficient and 1 is calculated, and an absolute value of the first difference is determined as the first weighting coefficient.

[0026] Optionally, determining the theoretical chargeable and dischargeable amount of the battery based on the chargeable and dischargeable capacity and the state of charge includes:

[0027] When the battery is in the full charge linear interval, calculating a second difference between 1 and the state of charge, and determining that the product of the chargeable and dischargeable capacity and the second difference is the theoretical chargeable and dischargeable capacity of the battery;

[0028] When the battery is in the full discharge linear interval, the product of the chargeable and dischargeable capacity and the state of charge is determined as the theoretical chargeable and dischargeable amount of the battery.

[0029] Optionally, determining the first SOH of the battery according to the actual charge and discharge amount and the theoretical charge and discharge amount includes:

[0030] The ratio of the actual charge and discharge amount to the theoretical charge and discharge amount is used as the first SOH of the battery.

[0031] Optionally, obtaining the chargeable and dischargeable capacity of the battery at the current temperature includes:

[0032] Determining the chargeable and dischargeable capacity of the battery at the current temperature based on the temperature-chargeable and dischargeable capacity table;

[0033] Or, based on the temperature conversion coefficient of the current temperature and the capacity of the battery at the standard temperature, the chargeable and dischargeable capacity of the battery at the current temperature is determined.

[0034] In a second aspect, the present application provides an energy storage SOH calibration device, comprising:

[0035] A time determination module, used to continuously monitor the open circuit voltage and current of the battery, and when the open circuit voltage reaches the full charge linear interval or the full discharge linear interval, record the current time as the first time, and obtain the chargeable and dischargeable capacity of the battery at the current temperature;

[0036] a state determination module, configured to determine a current state of charge of the battery based on the open circuit voltage corresponding to the first time;

[0037] A theoretical power acquisition module, used to determine the theoretical chargeable and dischargeable amount of the battery based on the chargeable and dischargeable capacity and the state of charge;

[0038] an actual power acquisition module, configured to record the current time as a second time when the open circuit voltage reaches a fully charged state or a fully discharged state, and perform time integration on the current of the battery from the first time to the second time to obtain the actual charge and discharge capacity of the battery;

[0039] The SOH acquisition module is used to determine a first SOH of the battery according to the actual charge and discharge amount and the theoretical charge and discharge amount.

[0040] In a third aspect, the present application provides an electronic device, including:

[0041] Memory, used to store computer programs;

[0042] The processor is used to execute the computer program to implement the above-mentioned SOH calibration method.

[0043] In a fourth aspect, the present application provides a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, the above-mentioned SOH calibration method is implemented.

[0044] From the above, it can be concluded that when the battery is in the full charge linear interval or the full discharge linear interval, there is an obvious and stable mapping relationship between its open circuit voltage and SOC (State Of Charge, remaining power), which can provide accurate SOC data for SOH calculation. Therefore, when the theoretical discharge capacity of the battery is determined by calculating the product of the state of charge and the chargeable and dischargeable capacity, a more accurate result can be obtained. In addition, unlike the prior art, which requires long-term and high-frequency collection of multi-dimensional data such as battery voltage, current, and temperature to determine the battery's SOH, this solution only needs to calculate the ratio of the actual charge and discharge capacity to the theoretical charge and discharge capacity during a full charge or full discharge process to determine the current battery's SOH, which greatly speeds up the calculation of SOH. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0046] Figure 1 A flow chart of a SOH calibration method disclosed in this application;

[0047] Figure 2 A specific first SOH calculation flow chart disclosed in this application;

[0048] Figure 3 This is a schematic diagram of OCV-SOC of a lithium iron phosphate battery disclosed in this application;

[0049] Figure 4 A specific SOH calibration method flow chart disclosed in this application;

[0050] Figure 5 A schematic diagram of a calibration coefficient determination process disclosed in this application;

[0051] Figure 6 A schematic diagram of weighted coefficient allocation disclosed in this application;

[0052] Figure 7 This is a schematic diagram of the structure of a SOH calibration device disclosed in this application;

[0053] Figure 8 This is a structural diagram of an electronic device disclosed in this application. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] As a core component in industrial and commercial energy storage systems, the performance of batteries directly affects the efficiency, reliability and safety of energy storage systems. Battery SOH (State Of Health) refers to the health status of the battery, which just reflects the degree of performance degradation of the battery relative to its initial state.

[0056] In the prior art, the SOH module calculation method for industrial and commercial energy storage is usually based on the number of charge and discharge cycles and calendar life of the energy storage system. However, since this calculation method is limited by factors such as temperature, DOD, and rate, it is difficult to quickly and effectively estimate the current system SOH.

[0057] To this end, the present application provides a SOH calibration solution to quickly calibrate the SOH of the current energy storage system.

[0058] See also Figure 1 , Figure 2 As shown, an embodiment of the present invention discloses a SOH calibration method, including:

[0059] Step S11, monitoring the open circuit voltage and current of the battery, when the open circuit voltage reaches the full charge linear interval or the full discharge linear interval, recording the current time as the first time, and obtaining the chargeable and dischargeable capacity of the battery at the current temperature;

[0060] In this embodiment, the open circuit voltage and the charge and discharge current of the battery are continuously monitored. When it is detected that the open circuit voltage reaches the full charge linear interval or the full discharge linear interval, the current time is recorded as the first time. At the same time, the charge and discharge capacity of the battery at the current temperature needs to be determined. It is understandable that the charge and discharge process of the battery is essentially a series of electrochemical reactions, which will be affected by temperature, and the internal resistance of the battery will also change with the rise and fall of temperature. Therefore, the charge and discharge capacity of the battery will change at different temperatures. When calculating SOH, if the actual charge and discharge capacity at the current temperature is not considered, but only based on the rated capacity or other fixed conditions. The capacity value will cause a large deviation between the calculation result of SOH and the actual health status of the battery. Therefore, in order to accurately calculate the SOH of the battery, it is necessary to obtain the actual charge and discharge capacity at the current temperature for subsequent calculations. There are two ways to obtain the actual charge and discharge capacity at the current temperature.

[0061] In a specific embodiment, the chargeable and dischargeable capacity of the battery at the current temperature is determined based on the temperature-chargeable and dischargeable capacity table. The temperature-chargeable and dischargeable capacity table is a data table that shows the change relationship of the chargeable and dischargeable capacity of the battery under different temperature conditions, which can intuitively reflect the capacity retention ability of the battery at different temperatures. In addition to obtaining the temperature-chargeable and dischargeable capacity table corresponding to the battery through self-experiments, most batteries are equipped with a specification manual when they leave the factory, which includes a temperature-chargeable and dischargeable capacity table. Therefore, the chargeable and dischargeable capacity of the battery at the current temperature can also be determined by directly comparing the temperature-chargeable and dischargeable capacity table in the specification manual.

[0062] In another specific embodiment, the temperature conversion coefficient δ based on the current temperature temp The capacity of the battery at the standard temperature is compared to determine the charge and discharge capacity of the battery at the current temperature. For some batteries that are greatly affected by temperature, the factory will provide a temperature conversion coefficient table or formula in the specification manual. For example Figure 2 As shown, the temperature conversion factor specified in the specification of a certain battery is as follows:

[0063] [15℃~35℃], δ temp =α1;

[0064] [0℃~15℃], δ temp =α2;

[0065] [35℃~50℃], δ temp =α3;

[0066] Based on the different δ corresponding to the above different temperature ranges temp The size of can be used to calculate the charge and discharge capacity Q of the battery at the current temperature. 额定 .

[0067] In this embodiment, it is necessary to calculate the SOH of the battery in the full charge linear interval or the full discharge linear interval of the battery. It should be noted that the full charge linear interval and the full discharge linear interval generally refer to the interval in which the voltage changes nearly linearly with the state of charge during the charging or discharging process of the battery, but not all batteries have a linear interval. For example, some special-purpose batteries, such as high-temperature batteries or high-power pulse batteries, have relatively complex charging and discharging characteristics due to their working principles and application scenarios, and may not have obvious full charge and full discharge linear intervals. During the charging and discharging process of these batteries, due to the particularity of the internal chemical reaction, the special requirements of the electrode material or the extreme working environment, the changes in parameters such as voltage and capacity may be nonlinear, and are greatly affected by external factors such as temperature and load.

[0068] In this embodiment, according to the charging characteristics of the lithium iron phosphate battery, the voltage of the lithium iron phosphate battery changes rapidly when it is close to being fully charged or fully discharged, forming a full charge linear interval and a full discharge linear interval. Therefore, this scheme can be used for the SOH calculation of the lithium iron phosphate battery.

[0069] Step S12, determining the current state of charge of the battery based on the open circuit voltage corresponding to the first time;

[0070] In this embodiment, after determining the first time, it is also necessary to obtain the open circuit voltage corresponding to the time, so as to determine the current state of charge of the battery according to the open circuit voltage of the battery. It is understandable that for most battery systems, such as lithium-ion batteries, nickel-metal hydride batteries, etc., when the battery is in different states of charge, the different degrees of chemical reactions inside the battery will cause the potential difference between the positive and negative electrodes to be different, thereby showing different voltage values. Therefore, there is a relatively stable corresponding relationship between the open circuit voltage and the state of charge of the battery.

[0071] Furthermore, through a large number of experimental tests and data analysis, the open circuit voltage-state of charge curve corresponding to a specific battery, namely the OCV-SOC curve, can be drawn, and the SOC corresponding to the battery at the current OCV (Open Circuit Voltage) can be determined by comparing the OCV-SOC curve. Figure 3 The OCV-SOC diagram of lithium iron phosphate battery, the horizontal axis is the state of charge of the battery, the vertical axis is the open circuit voltage of the battery, the solid line is the charging curve of the lithium iron phosphate battery, the dotted line is the discharge curve of the lithium iron phosphate battery, and the SOC between [0.9, 1.0] and [0, 0.15] is the linear range of full charge and full discharge of the lithium iron phosphate battery. Figure 2As shown, when the open circuit voltage is detected to be within the chg_interval interval or the dis_interval interval, the current battery state of charge can be determined through the above OCV-SOC table, and the current first time T_start is recorded. It can be understood that the above chg_interval interval and dis_interval interval are the above full charge linear interval and full discharge linear interval.

[0072] It should be noted that the battery needs to be left to stand for a period of time before measuring the open circuit voltage of the battery. Because during the charge and discharge process of the battery, complex chemical reactions will occur inside, causing the chemical state and potential distribution on the electrode surface to change continuously, and this change will cause the open circuit voltage of the battery to fluctuate. After standing for a period of time, the chemical reaction inside the battery will gradually tend to equilibrium, and the chemical concentration and potential distribution on the electrode surface will also tend to be stable. Therefore, the open circuit voltage measured at this time can accurately reflect the real potential difference inside the battery, thereby more accurately judging the battery's state of charge.

[0073] Step S13, determining the theoretical charge and discharge capacity of the battery based on the charge and discharge capacity and the state of charge;

[0074] In this embodiment, by calculating the chargeable and dischargeable capacity and the state of charge at the current temperature, the current theoretical chargeable and dischargeable capacity of the battery can be obtained.

[0075] In this embodiment, when the battery is in the full charge linear interval, the second difference between 1 and the state of charge is calculated, and the product of the chargeable and dischargeable capacity and the second difference is determined as the theoretical chargeable and dischargeable capacity of the battery; when the battery is in the full discharge linear interval, the product of the chargeable and dischargeable capacity and the state of charge is determined as the theoretical chargeable and dischargeable capacity of the battery. It can be understood that when the battery is in the full discharge linear interval, it is necessary to calculate the amount of electricity that can still be discharged, so the product of the chargeable and dischargeable capacity of the battery at the current temperature and the state of charge can be used as the theoretical chargeable and dischargeable capacity of the battery. When the battery is in the full charge linear interval, it is necessary to calculate the amount of electricity that can still be charged, so it is necessary to calculate the difference between the chargeable and dischargeable capacity at the current temperature and the product of the chargeable and dischargeable capacity at the current temperature and the state of charge as the theoretical chargeable and dischargeable capacity of the battery.

[0076] Step S14: when the open circuit voltage reaches a fully charged state or a fully discharged state, the current time is recorded as a second time, and the current of the battery from the first time to the second time is time-integrated to obtain the actual charge and discharge amount of the battery;

[0077] In this embodiment, when the battery reaches full charge or full discharge, the current time is recorded as the second time, and the discharge amount or charge amount of the battery from the first time to the second time is calculated, that is, the actual charge and discharge amount of the battery. The specific formula is as follows:

[0078] ;

[0079] Among them, chg_dischg_Cap is the charge and discharge amount of the battery in the full charge linear interval or the full discharge linear interval, T_end is the second time, T_start is the first time, and I is the charge and discharge current of the battery.

[0080] It is understandable that in order to speed up the acquisition of the actual charge and discharge capacity, e.g. Figure 3 As shown, considering that the speed at which the open circuit voltage of the lithium iron phosphate battery changes with the SOC in the full charge linear interval and the full discharge linear interval is much faster than the plateau period, if the battery is in the full charge linear interval at the first time, it is necessary to record the second time when the battery reaches the full charge state; if the battery is in the full discharge linear interval at the first time, it is necessary to record the second time when the battery reaches the full discharge state.

[0081] Step S15, determining the first SOH of the battery according to the actual charge and discharge capacity and the theoretical charge and discharge capacity.

[0082] In this embodiment, the current health state of the battery is determined based on the actual charge and discharge capacity and the theoretical charge and discharge capacity.

[0083] In this embodiment, the ratio of the actual charge and discharge capacity to the theoretical charge and discharge capacity is used as the first SOH of the battery. The specific formula is as follows:

[0084] ;

[0085] Among them, SOH quick_cal is the first SOH, SOC is the state of charge corresponding to the open circuit voltage at the first time, Q 额定 is the chargeable and dischargeable capacity at the current temperature.

[0086] It should be noted that the essence of SOH is the ratio of the current capacity of the battery to the initial capacity. As the battery is used and aged, a series of irreversible physical and chemical changes will occur inside the battery, such as the loss of electrode materials, the reduction of active substances, the decomposition of electrolytes, etc. These changes will cause the actual charge and discharge capacity of the battery to gradually decrease, while the theoretical charge and discharge capacity remains basically unchanged. Therefore, the ratio of the actual charge and discharge capacity of the battery to the theoretical charge and discharge capacity can intuitively reflect the degree of battery capacity attenuation, and then determine the battery's SOH.

[0087] From the above, it can be seen that when the battery is in the full charge linear interval or the full discharge linear interval, there is an obvious and stable mapping relationship between its open circuit voltage and SOC, which can provide accurate SOC data for SOH calculation. Therefore, when the theoretical discharge capacity of the battery is determined by calculating the product of the state of charge and the chargeable and dischargeable capacity, a more accurate result can be obtained. In addition, unlike the prior art, which requires long-term and high-frequency collection of multi-dimensional data such as battery voltage, current, and temperature to determine the battery's SOH, this solution only needs to calculate the ratio of the actual charge and discharge capacity to the theoretical charge and discharge capacity during a full charge or full discharge process. The SOH of the current battery can be determined, which greatly speeds up the calculation of SOH.

[0088] In order to make the calculated SOH more accurate, refer to Figure 3 As shown, the embodiment of the present application discloses a specific SOH calibration method, which may include:

[0089] Step S21, each time charging and discharging is successful, the number of successful charging and discharging of the battery is increased by 1 to determine the total number of successful charging and discharging of the battery in one day;

[0090] In this embodiment, the number of successful charge and discharge of the battery in one day is continuously recorded to record the total number of charge and discharge of the battery in one day. Figure 2 As shown, Cnt_success can be accumulated after each calculation of the first SOH and reset to zero every day to determine that the final Cnt_success is the number of successful charge and discharge times in one day, that is, the total number of successful charge and discharge times.

[0091] Step S22, determining a calibration coefficient based on the total number of successful charge and discharge operations;

[0092] In this embodiment, the calibration coefficient of the battery can be determined by the total number of successful charge and discharge of the battery in one day. It is understandable that if only one charge or discharge is performed in one day, the value of the first SOH obtained may deviate greatly from the actual situation. Therefore, as the total number of charge and discharge times in one day increases, the first SOH is calculated multiple times, so that the first SOH finally obtained for weighted calculation is more accurate and easier to eliminate interference.

[0093] In a specific embodiment, in order to achieve profitability, industrial and commercial energy storage often adopts the "two charges and two discharges" application strategy, that is, charging twice a day and discharging twice a day. Under normal circumstances, the total number of successful charging and discharging is 4. Figure 5As shown, in the process of determining Cnt_success, whenever it is detected that the highest cell voltage of the energy storage system is greater than 3.45V, or the lowest cell voltage is less than 3.15V, it can be determined that the current energy storage system is in the full charge linear interval or the full discharge linear interval, so it is continuously determined whether the above-mentioned highest cell voltage reaches 3.65V, that is, the full charge state, or whether the above-mentioned lowest cell voltage reaches 2.75V, that is, the full discharge state, if so, Cnt_success is increased by 1. At this time, if the total charge and discharge times of the battery in the storage system in one day is 4, the calibration coefficient is determined to be 0.9; if the total charge and discharge times of the battery in the storage system in one day is 3, the calibration coefficient is determined to be 0.8; if the total charge and discharge times of the battery in the storage system in one day is 2, the calibration coefficient is determined to be 0.6; if the total charge and discharge times of the battery in the storage system in one day is 1, the calibration coefficient is determined to be 0.4; if the total charge and discharge times of the battery in the storage system in one day is 0, the calibration coefficient is determined to be 0.1.

[0094] It is understandable that the comprehensive SOH of the energy storage system needs to be calculated once a day, so the above operation of judging the total number of successful charging and discharging times of the batteries in the energy storage system only needs to be judged once when calculating the comprehensive SOH.

[0095] It should be noted that, in order to ensure the accuracy of the first SOH, the total number of charge and discharge times also has a maximum value, which depends on the fixed number of charge and discharge times in the energy storage system.

[0096] Therefore, in the above-mentioned industrial and commercial energy storage, if the total number of charge and discharge times of the batteries in the storage system exceeds 4 in one day, it means that there may be an abnormality in the energy storage system on that day, and the first SOH value recorded on that day is also unreliable, so the calibration coefficient is determined to be 0.

[0097] Step S23, determining a first weighting coefficient and a second weighting coefficient based on the calibration coefficient and a preset constraint condition; wherein the sum of the first weighting coefficient, the second weighting coefficient and the calibration coefficient is 1.

[0098] In this embodiment, the first weighting coefficient and the second weighting coefficient are determined according to the calibration coefficient. It can be understood that the calibration coefficient is also a weighting coefficient, and the sum of the weighting coefficients is 1.

[0099] In a specific implementation, it is determined whether the calibration coefficient is greater than a preset threshold; if greater, the second weighting coefficient is determined to be 0.02; if less, the second weighting coefficient is determined to be 0.1; a first difference between the sum of the calibration coefficient and the second weighting coefficient and 1 is calculated, and the absolute value of the first difference is determined to be the first weighting coefficient. Further, if Figure 6As shown, the preset threshold is set to 0.9, where γ is the calibration coefficient, α and β are the first weighting coefficient and the second weighting coefficient respectively. At this time, the value of the second weighting coefficient is relatively smaller, which means that its corresponding weight is smaller.

[0100] Step S24, determining that the first weighting coefficient, the second weighting coefficient and the calibration coefficient are weighting coefficients corresponding to the second SOH, the third SOH and the comprehensive SOH in sequence; wherein the comprehensive SOH is obtained by combining all the first SOHs calculated within one day;

[0101] In this embodiment, the weighting coefficients corresponding to the second SOH, the third SOH and the comprehensive SOH are determined in turn, wherein the comprehensive SOH corresponds to the calibration coefficient, the second SOH corresponds to the first weighting coefficient, and the third SOH corresponds to the second weighting coefficient. It can be understood that multiple first SOHs can be obtained by calculating based on the actual charge and discharge capacity and the theoretical charge and discharge capacity within one day. In order to avoid the influence of abnormal values ​​on the calculation results, it is necessary to conduct a comprehensive evaluation of the above multiple first SOHs, remove obvious abnormal values, and adopt comprehensive calculation methods such as weighted average method and comprehensive index method to obtain a comprehensive SOH that can reflect all normal data and participate in subsequent weighted calculations.

[0102] In this embodiment, the second SOH of the battery is determined based on the actual charge and discharge amount and the nominal capacity of the battery through the cycle-SOH table; the shelf time of the battery is obtained, and based on the shelf time, the third SOH of the battery is determined through the attenuation table corresponding to the battery. In order to make the calculated battery health more accurate, the SOH can be calculated simultaneously by multiple methods, and the SOH calculated by different methods can be analyzed as a whole to obtain a more accurate overall SOH that is closer to the actual battery health status.

[0103] Specifically, the second SOH is determined by the cycle of the battery, the battery current is integrated over time to obtain the charge and discharge power, and the power is stored in the memory in real time. The number of cycles of the battery can be obtained by mapping the storage capacity and the nominal capacity value. It should be noted that the battery manufacturer will also provide the battery cycle-SOH table when the battery leaves the factory, so the second SOH of the battery can be determined based on the cycle-SOH table.

[0104] Furthermore, the third SOH is determined by the storage time of the battery. As the storage time increases, the capacity of the lithium iron phosphate battery will also decay to a certain extent. The BMS (Battery Management System) controller software can calculate the storage time of the battery in real time, and at the same time, according to the decay table provided by the battery manufacturer, map the third SOH corresponding to the storage time. Since industrial and commercial energy storage needs to operate for a long time, this value has little impact on the overall SOH value and can correspond to the second weighting coefficient mentioned above.

[0105] Step S25: Based on the weighting coefficient, perform weighted calculation on the second SOH, the third SOH and the comprehensive SOH to determine the overall SOH of the battery.

[0106] In this embodiment, after determining the weights corresponding to the SOH obtained in different ways, the overall SOH of the battery is determined by weighted calculation. It can be understood that compared with calculating SOH by a single method, using weighted calculation can make the final SOH more accurate and closer to the actual value. The specific formula can be:

[0107] ;

[0108] Among them, SOH is the overall SOH, SOH cycle is the second SOH determined by the number of cycles, SOH calendar is the third SOH determined by the shelf time, α is the first weighting coefficient, β is the second weighting coefficient, and γ is the calibration coefficient.

[0109] From the above, it can be concluded that the SOH of the battery obtained by the three methods is weightedly calculated. According to the importance of the first SOH, the weight of the first SOH in the calculation is reasonably planned to perform comprehensive calculations on the values ​​of multiple SOHs, so that the final overall SOH is more accurate.

[0110] Accordingly, see Figure 7 As shown, the embodiment of the present application also provides a SOH calibration device, which may include:

[0111] The time determination module 11 is used to monitor the open circuit voltage and current of the battery, and when the open circuit voltage reaches the full charge linear interval or the full discharge linear interval, record the current time as the first time, and obtain the chargeable and dischargeable capacity of the battery at the current temperature;

[0112] a state determination module 12, configured to determine a current state of charge of the battery based on the open circuit voltage corresponding to the first time;

[0113] Theoretical power acquisition module 13, used to determine the theoretical chargeable and dischargeable amount of the battery based on the chargeable and dischargeable capacity and the state of charge;

[0114] The actual power acquisition module 14 is used to record the current time as the second time when the open circuit voltage reaches the full charge state or the full discharge state, and perform time integration on the current of the battery from the first time to the second time to obtain the actual charge and discharge capacity of the battery;

[0115] The first SOH acquisition module 15 is used to determine the first SOH of the battery according to the actual charge and discharge amount and the theoretical charge and discharge amount.

[0116] From the above, it can be seen that when the battery is in the full charge linear interval or the full discharge linear interval, there is an obvious and stable mapping relationship between its open circuit voltage and SOC, which can provide accurate SOC data for SOH calculation. Therefore, when the theoretical discharge capacity of the battery is determined by calculating the product of the state of charge and the chargeable and dischargeable capacity, a more accurate result can be obtained. In addition, unlike the prior art, which requires long-term and high-frequency collection of multi-dimensional data such as battery voltage, current, and temperature to determine the battery's SOH, this solution only needs to calculate the ratio of the actual charge and discharge capacity to the theoretical charge and discharge capacity during a full charge or full discharge process. The SOH of the current battery can be determined, which greatly speeds up the calculation of SOH.

[0117] In some specific implementations, the SOH calibration device further includes:

[0118] A second SOH acquisition module, configured to determine a second SOH of the battery through a cycle-SOH table based on the actual charge and discharge amount and the nominal capacity of the battery;

[0119] The third SOH acquisition module is used to acquire the shelf life of the battery, and determine the third SOH of the battery based on the shelf life and through the attenuation table corresponding to the battery.

[0120] In some specific implementations, the first SOH acquisition module 15 further includes:

[0121] A times acquisition unit, used for adding 1 to the times of successful charging and discharging of the battery each time charging and discharging succeeds, so as to determine the total times of successful charging and discharging of the battery in one day;

[0122] A first coefficient acquisition unit, configured to determine a calibration coefficient based on the total number of successful charge and discharge times;

[0123] The second coefficient acquisition unit is used to determine the first weighting coefficient and the second weighting coefficient based on the calibration coefficient and the preset constraint condition; wherein the sum of the first weighting coefficient, the second weighting coefficient and the calibration coefficient is 1.

[0124] A coefficient allocation unit, configured to determine that the first weighting coefficient, the second weighting coefficient, and the calibration coefficient are weighting coefficients corresponding to the second SOH, the third SOH, and the comprehensive SOH in sequence; wherein the comprehensive SOH is obtained by combining all the first SOHs calculated within one day;

[0125] The overall SOH determination unit is used to perform weighted calculation on the second SOH, the third SOH and the comprehensive SOH based on the weighting coefficient to determine the overall SOH of the battery.

[0126] In some specific implementations, the second coefficient acquisition unit may specifically include:

[0127] Determining whether the calibration coefficient is greater than a preset threshold;

[0128] If it is greater than, the second weighting coefficient is determined to be 0.02;

[0129] If it is less than, the second weighting coefficient is determined to be 0.1;

[0130] A first difference between the sum of the calibration coefficient and the second weighting coefficient and 1 is calculated, and an absolute value of the first difference is determined as the first weighting coefficient.

[0131] In some specific implementations, the theoretical power acquisition module 13 includes:

[0132] a first theoretical power acquisition unit, configured to calculate, when the battery is in the full charge linear interval, a second difference between 1 and the state of charge, and determine that the product of the chargeable and dischargeable capacity and the second difference is the theoretical chargeable and dischargeable capacity of the battery;

[0133] The second theoretical power acquisition unit is used to determine the product of the chargeable and dischargeable capacity and the state of charge as the theoretical chargeable and dischargeable capacity of the battery when the battery is in the full discharge linear interval.

[0134] In some specific implementations, the first SOH acquisition module 15 includes:

[0135] The first SOH determining unit is used to use the ratio of the actual charge and discharge amount to the theoretical charge and discharge amount as the first SOH of the battery.

[0136] In some specific implementations, the time determination module 11 includes:

[0137] A first capacity acquisition unit, configured to determine the chargeable and dischargeable capacity of the battery at a current temperature based on a temperature-chargeable and dischargeable capacity table;

[0138] The second capacity acquisition unit is used to determine the chargeable and dischargeable capacity of the battery at the current temperature based on the temperature conversion coefficient of the current temperature and the capacity of the battery at the standard temperature.

[0139] Furthermore, the present application also discloses an electronic device. Figure 8 It is a structural diagram of an electronic device 20 shown according to an exemplary embodiment, and the content in the figure cannot be regarded as any limitation on the scope of use of this application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. Among them, the memory 22 is used to store a computer program, and the computer program is loaded and executed by the processor 21 to implement the relevant steps in the SOH calibration method disclosed in any of the aforementioned embodiments. In addition, the electronic device 20 in this embodiment may specifically be an electronic computer.

[0140] In this embodiment, the power supply 23 is used to provide working voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and the external device, and the communication protocol it follows is any communication protocol that can be applied to the technical solution of the present application, and is not specifically limited here; the input and output interface 25 is used to obtain external input data or output data to the outside world, and its specific interface type can be selected according to specific application needs and is not specifically limited here.

[0141] In addition, the memory 22, as a carrier for storing resources, can be a read-only memory, a random access memory, a disk or an optical disk, etc. The resources stored thereon can include an operating system 221, a computer program 222, etc., and the storage method can be temporary storage or permanent storage.

[0142] The operating system 221 is used to manage and control the hardware devices and computer program 222 on the electronic device 20, which can be Windows Server, Netware, Unix, Linux, etc. In addition to including a computer program that can be used to complete the SOH calibration method performed by the electronic device 20 disclosed in any of the aforementioned embodiments, the computer program 222 can further include a computer program that can be used to complete other specific tasks.

[0143] Furthermore, the present application also discloses a computer-readable storage medium for storing a computer program; wherein the computer program, when executed by a processor, implements the aforementioned SOH calibration method. The specific steps of the method can refer to the corresponding contents disclosed in the aforementioned embodiments, and will not be repeated here.

[0144] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0145] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0146] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0147] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0148] The technical solution provided by the present application is introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for general technicians in this field, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A SOH calibration method, characterized in that: include: Monitor the open circuit voltage and current of the battery, and when the open circuit voltage reaches the full charge linear interval or the full discharge linear interval, record the current time as the first time, and obtain the chargeable and dischargeable capacity of the battery at the current temperature; determining a current state of charge of the battery based on the open circuit voltage corresponding to the first time; Determining a theoretical chargeable and dischargeable amount of the battery based on the chargeable and dischargeable capacity and the state of charge; When the open circuit voltage reaches a fully charged state or a fully discharged state, the current time is recorded as a second time, and the current of the battery from the first time to the second time is time-integrated to obtain an actual charge and discharge amount of the battery; A first SOH of the battery is determined according to the actual charge and discharge amount and the theoretical charge and discharge amount.

2. The SOH calibration method according to claim 1, characterized in that: Also includes: Determining a second SOH of the battery through a cycle-SOH table based on the actual charge and discharge amount and the nominal capacity of the battery; The storage time of the battery is obtained, and based on the storage time, a third SOH of the battery is determined by using a decay table corresponding to the battery.

3. The SOH calibration method according to claim 2, characterized in that: After performing time integration on the current of the battery from the first time to the second time to obtain the actual charge and discharge amount of the battery, the method further includes: Each time charging and discharging is successful, the number of successful charging and discharging of the battery is increased by 1 to determine the total number of successful charging and discharging of the battery in one day; Determining a calibration coefficient based on the total number of successful charge and discharge times; Determine a first weighting coefficient and a second weighting coefficient based on the calibration coefficient and a preset constraint condition; wherein the sum of the first weighting coefficient, the second weighting coefficient and the calibration coefficient is 1; Determine that the first weighting coefficient, the second weighting coefficient, and the calibration coefficient are weighting coefficients corresponding to the second SOH, the third SOH, and the comprehensive SOH in sequence; wherein the comprehensive SOH is obtained by combining all the first SOHs calculated within one day; Based on the weighting coefficient, the second SOH, the third SOH and the comprehensive SOH are weighted and calculated to determine the overall SOH of the battery.

4. The SOH calibration method according to claim 3, characterized in that: The determining the first weighting coefficient and the second weighting coefficient based on the calibration coefficient and the preset constraint condition comprises: Determining whether the calibration coefficient is greater than a preset threshold; If it is greater than, the second weighting coefficient is determined to be 0.02; If it is less than, the second weighting coefficient is determined to be 0.1; A first difference between the sum of the calibration coefficient and the second weighting coefficient and 1 is calculated, and an absolute value of the first difference is determined as the first weighting coefficient.

5. The SOH calibration method according to any one of claims 1 to 4, characterized in that: The determining, based on the chargeable and dischargeable capacity and the state of charge, a theoretical chargeable and dischargeable amount of the battery comprises: When the battery is in the full charge linear interval, calculating a second difference between 1 and the state of charge, and determining that the product of the chargeable and dischargeable capacity and the second difference is the theoretical chargeable and dischargeable capacity of the battery; When the battery is in the full discharge linear interval, the product of the chargeable and dischargeable capacity and the state of charge is determined as the theoretical chargeable and dischargeable amount of the battery.

6. The SOH calibration method according to claim 1, characterized in that: The determining the first SOH of the battery according to the actual charge and discharge amount and the theoretical charge and discharge amount includes: The ratio of the actual charge and discharge amount to the theoretical charge and discharge amount is used as the first SOH of the battery.

7. The SOH calibration method according to claim 1, characterized in that: The obtaining of the chargeable and dischargeable capacity of the battery at the current temperature includes: Determining the chargeable and dischargeable capacity of the battery at the current temperature based on the temperature-chargeable and dischargeable capacity table; Or, based on the temperature conversion coefficient of the current temperature and the capacity of the battery at the standard temperature, the chargeable and dischargeable capacity of the battery at the current temperature is determined.

8. An energy storage SOH calibration device, characterized in that: include: A time determination module, used to continuously monitor the open circuit voltage and current of the battery, and when the open circuit voltage reaches the full charge linear interval or the full discharge linear interval, record the current time as the first time, and obtain the chargeable and dischargeable capacity of the battery at the current temperature; a state determination module, configured to determine a current state of charge of the battery based on the open circuit voltage corresponding to the first time; A theoretical power acquisition module, used to determine the theoretical chargeable and dischargeable amount of the battery based on the chargeable and dischargeable capacity and the state of charge; an actual power acquisition module, configured to record the current time as a second time when the open circuit voltage reaches a fully charged state or a fully discharged state, and perform time integration on the current of the battery from the first time to the second time to obtain the actual charge and discharge capacity of the battery; The SOH acquisition module is used to determine a first SOH of the battery according to the actual charge and discharge amount and the theoretical charge and discharge amount.

9. An electronic device, characterized in that: include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the SOH calibration method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: Used to store a computer program; wherein, when the computer program is executed by a processor, the SOH calibration method according to any one of claims 1 to 7 is implemented.

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