Method for obtaining residual electric quantity of battery and battery

Abstract

The invention provides a method for obtaining the remaining capacity of a battery and the battery. The method comprises a modeling stage and an application stage, and the modeling stage comprises the following steps: collecting a plurality of discharge depths of at least one cell module in the battery and a plurality of potential parameters respectively corresponding to the plurality of discharge depths at a plurality of preset temperatures; and establishing a potential parameter-discharge depth matching model of the battery at a plurality of preset temperatures. The application stage comprises the step of obtaining the real-time discharge depth of at least one battery cell module. And obtaining the residual electric quantity of the battery according to the real-time discharge depth of the at least one battery cell module. Therefore, according to the method for obtaining the residual electric quantity of the battery and the battery provided by the invention, the mapping relation between the potential parameter and the discharge depth can be established according to the potential parameter of the battery, so that the accurate and high-precision residual electric quantity of the battery can be obtained through the mapping relation.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method for obtaining the remaining power of a battery and a battery. Background Art

[0002] During the process of battery charging and discharging, it is necessary to obtain the remaining capacity of the battery in real time. The remaining capacity of the battery is usually represented by the relative state-of-charge (RSOC), which can be calculated based on the depth of discharge (DOD) of the battery, and the DOD of the battery is usually obtained based on the predicted battery electrochemical model parameter table OCV (DOD, T). Specifically, OCV (DOD, T) includes a mapping curve diagram of the open circuit voltage (OCV) of the battery and the DOD of the battery. Therefore, by real-time detection of the OCV of the battery during the charging and discharging process, the real-time DOD of the battery can be obtained through OCV (DOD, T), and then the RSOC of the battery can be obtained. However, during the charging and discharging process of the battery, the DOD changes greatly while the corresponding open circuit voltage may change less, making the calculated RSOC of the battery not very accurate. Summary of the invention

[0003] In view of the above problems, the present application provides a method for obtaining the remaining power of a battery and a battery, which can establish a mapping relationship between potential parameters and discharge depth according to the potential parameters of the battery, so as to obtain the accurate and high-precision remaining power of the battery through the mapping relationship.

[0004] In a first aspect, the present application provides a method for obtaining the remaining power of a battery, including a modeling stage and an application stage. The modeling stage includes: at multiple preset temperatures, during the process of discharging the battery from a discharge depth of 0% to a discharge depth of 100%, collecting multiple discharge depths of at least one battery module in the battery and multiple potential parameters corresponding to the multiple discharge depths, wherein each battery module includes a reference electrode, and the potential parameters include the positive electrode potential between the positive electrode and the reference electrode in the battery module, and / or the negative electrode potential between the negative electrode and the reference electrode; establishing a potential parameter-discharge depth matching model of the battery at multiple preset temperatures according to the multiple discharge depths of at least one battery module and the multiple potential parameters corresponding to the multiple discharge depths; the application stage includes: obtaining the real-time potential parameters and current temperature of at least one battery module in the battery during the discharge process; obtaining the real-time discharge depth of at least one battery module according to the potential parameter-discharge depth matching model and the real-time potential parameters corresponding to at least one battery module at the current temperature; and obtaining the remaining power of the battery according to the real-time discharge depth of at least one battery module.

[0005] In combination with the first aspect, in a possible implementation, before the modeling stage, the method also includes a potential parameter determination stage, and the potential parameter determination stage includes: at a preset temperature, during the process of discharging the battery from a discharge depth of 0% to a discharge depth of 100%, collecting multiple current discharge depths of at least one battery cell module in the battery, multiple positive electrode potentials corresponding to the multiple current discharge depths, and multiple negative electrode potentials corresponding to the multiple current discharge depths; determining one of the multiple positive electrode potentials and the multiple negative electrode potentials as a potential parameter based on the change rates of the multiple positive electrode potentials and the multiple negative electrode potentials with the corresponding multiple current discharge depths.

[0006] In combination with the first aspect, in a possible implementation, according to the change rates of the multiple positive electrode potentials and the multiple negative electrode potentials with the corresponding multiple current discharge depths, one of the multiple positive electrode potentials and the multiple negative electrode potentials is determined as a potential parameter, including: determining the highest one of the change rates of the multiple positive electrode potentials and the multiple negative electrode potentials with the corresponding multiple current discharge depths as the potential parameter.

[0007] In combination with the first aspect, in a possible implementation manner, the potential parameter is the negative electrode potential between the negative electrode and the reference electrode.

[0008] In combination with the first aspect, in a possible implementation manner, the modeling stage further includes: determining a discharge current of the battery.

[0009] In combination with the first aspect, in a possible implementation, determining the discharge current of the battery includes: when the discharge start temperature is a preset temperature, performing constant current discharge on the battery with multiple preset discharge currents, collecting multiple discharge cut-off temperatures corresponding to the multiple preset discharge currents when the constant current discharge of the battery is cut off; and determining that a preset discharge current corresponding to a value whose difference between the preset temperature and the multiple discharge cut-off temperatures is less than a preset temperature threshold is the discharge current of the battery.

[0010] In combination with the first aspect, in a possible implementation, determining the discharge current of the battery includes: discharging the battery with multiple preset discharge currents at the same preset temperature, collecting the initial battery capacity of the battery at the start of discharge, and multiple discharge cut-off capacities corresponding to the multiple preset discharge currents at the end of discharge; determining that the preset discharge current corresponding to a preset capacity threshold value when the difference between the initial battery capacity and the discharge cut-off capacity is less than is the discharge current of the battery.

[0011] In combination with the first aspect, in a possible implementation, determining the discharge current of the battery includes: discharging the battery with multiple preset discharge currents at the same preset temperature, and collecting multiple voltage change rates of the battery and multiple time durations for each voltage change rate to be reduced to the preset change rate at each preset discharge depth; and determining at least one of the multiple preset discharge currents as the discharge current of the battery according to the multiple time durations.

[0012] In combination with the first aspect, in a possible implementation, the remaining power of the battery is obtained according to the real-time discharge depth of at least one battery cell module, including: obtaining the remaining power of each battery cell module according to the real-time discharge depth of at least one battery cell module; and taking the remaining power of the battery cell module with the lowest remaining power as the remaining power of the battery.

[0013] In combination with the first aspect, in a possible implementation, the remaining power of each battery cell module is obtained according to the real-time discharge depth of at least one battery cell module, including: obtaining the remaining power from the real-time discharge depth according to a preset relationship between the discharge depth and the remaining power; wherein the preset relationship includes: the sum of the discharge depth and the remaining power is 1.

[0014] In a second aspect, the present application provides a battery, comprising at least one battery cell module and a battery management system, each battery cell module comprising a positive electrode, a reference electrode and a negative electrode, the reference electrode having a constant potential, the battery management system being electrically connected to the battery cell module, and the battery management system being used to execute a method for obtaining the remaining power of a battery as provided in any possible implementation of the first aspect.

[0015] In combination with the second aspect, in a possible implementation, the battery management system includes a negative electrode potential sampling circuit, which is electrically connected to a reference electrode and a negative electrode in at least one battery cell module, and is used to collect the negative electrode potential of at least one battery cell module.

[0016] In conjunction with the second aspect, in a possible implementation, the battery is a lithium iron phosphate battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the battery electrochemical model parameter table.

[0018] Figure 2 Schematic diagram of the battery provided for this application.

[0019] Figure 3 A schematic diagram of the battery cell module provided in this application.

[0020] Figure 4 A flow chart of a method for obtaining the remaining power of a battery provided in this application.

[0021] Figure 5 Another flow chart of the method for obtaining the remaining power of a battery provided in this application.

[0022] Figure 6 This is another flow chart of the method for obtaining the remaining power of a battery provided in the present application.

[0023] Figure 7 Schematic diagram of the potential parameter-discharge depth matching model provided in this application.

[0024] Figure 8 A flow chart of a method for determining the discharge current of a battery.

[0025] Fig. 9 A flow chart of another method for determining the discharge current of a battery.

[0026] Fig.10 A flow chart of another method for determining the discharge current of a battery. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application.

[0028] It is understandable that the connection relationship described in this application refers to direct or indirect connection. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components. For example, A and C can be directly connected, and C and B can be directly connected, so that A and B are connected through C. It is also understandable that the "A connects B" described in this application can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.

[0029] In the description of this application, unless otherwise specified, " / " means "or", for example, A / B can mean A or B. "And / or" in this article is only a way to describe the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0030] In the description of this application, words such as "first" and "second" are only used to distinguish different objects, and do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit differences. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0031] During the process of battery charging and discharging, it is necessary to obtain the remaining capacity of the battery in real time. The remaining capacity of the battery is usually represented by the relative state-of-charge (RSOC), which can be calculated based on the depth of discharge (DOD) of the battery, and the DOD of the battery is usually obtained based on the predicted battery electrochemical model parameter table OCV (DOD, T). Specifically, OCV (DOD, T) includes a mapping curve diagram of the open circuit voltage (OCV) of the battery and the DOD of the battery. Therefore, by real-time detection of the OCV of the battery during the charging and discharging process, the real-time DOD of the battery can be obtained through OCV (DOD, T), and then the RSOC of the battery can be obtained. However, during the charging and discharging process of the battery, the DOD changes greatly while the corresponding open circuit voltage may change less, making the calculated RSOC of the battery not very accurate.

[0032] For example, Figure 1 As shown in the figure, OCV(DOD,T) can be expressed as the change of the OCV of the battery during the process of discharging from 0% depth of discharge to 100% depth of discharge. Therefore, by detecting the OCV of the battery in real time, the real-time DOD of the battery corresponding to the OCV can be obtained according to OCV(DOD,T), and then the RSOC of the battery can be calculated. However, when the DOD is in the range of (2%, 40%), the OCV of the battery corresponds to about 3300mV, that is, the corresponding open circuit voltage may change less while the DOD changes more. Here, the DOD interval that meets this condition is defined as the voltage flat interval. Therefore, when the OCV of the battery is detected to be about 3300mV, the real-time DOD of the battery corresponding to the OCV obtained according to OCV(DOD,T) may be in the range of (2%, 40%). Since the value range of DOD is large, the accuracy of the RSOC of the battery further calculated according to DOD is small.

[0033] In the voltage flat range, the RSOC of the battery is usually updated by Coulomb integration to improve the calculation precision and accuracy of RSOC. However, Coulomb integration requires the acquisition of the battery current, and the battery current may have slight fluctuations. After a long period of accumulation, the slight fluctuations will also cause the RSOC of the battery updated by Coulomb integration to have low accuracy and large errors.

[0034] Therefore, the present application provides a method for obtaining the remaining power of a battery and a battery, which can establish a mapping relationship between potential parameters and discharge depth according to the potential parameters of the battery, thereby obtaining the accurate and highly precise remaining power of the battery through the mapping relationship.

[0035] See also Figure 2 , Figure 2 The schematic diagram of the battery 10 provided in the present application is as follows. The battery 10 includes a battery management system 11 and at least one battery cell module 12. The battery management system 11 includes a sampling module 111 and a calculation control module 112.

[0036] The battery cell module 12 is used to output electrical energy to supply power to the load. The number of battery cell modules 12 can be one or two or more. When the number of battery cell modules 12 is two or more, the two or more battery cell modules 12 can be connected in series, in parallel, in mixed connection, etc., and the present application does not impose any restrictions on the number of battery cell modules 12 and their connection methods. The load may include electrical equipment, energy storage equipment, and other equipment that receives electrical energy, such as terminal equipment, batteries, inverters, etc. The present application does not impose any restrictions on the type of load.

[0037] The battery management system 11 is electrically connected to each battery module 12. The battery management system 11 is used to detect the parameters of the battery module 12 and to control the battery module 12 accordingly. Specifically, the sampling module 111 is used to detect the parameters of the battery module 12, and the calculation control module 112 is used to control the battery module 12 accordingly.

[0038] For example, the sampling module 111 can detect the output voltage, output current, output power, temperature and other parameters of the battery module 12, and the calculation and control module 112 can adjust the output voltage, output current, output power and the like of the battery module 12 based on the parameters collected by the sampling module 111. For another example, the sampling module 111 can detect the state of charge, charging or discharging voltage, charging or discharging current, temperature, number of cycles and other parameters of the battery module 12 during the charging or discharging process, and the calculation and control module 112 can adjust the charging state or discharge state of the battery module 12 based on the parameters collected by the sampling module 111. The charging state includes the charging mode, charging parameters and the like, and the charging mode includes one of the charging modes such as constant current charging, constant voltage charging, constant power charging, or different combinations of the above charging modes. The charging parameters include one of the parameters such as the charging start voltage, the charging start current, the charging cut-off voltage, the charging cut-off current, the charging start state of charge, the charging cut-off state of charge and the like, or different combinations of the above parameters. Similarly, the discharge state is similar to the charging state, and will not be repeated here.

[0039] In some embodiments, the sampling module 111 and the computing control module 112 can be integrated on the same chip, or integrated on different chips, or two independently configured circuits that are not integrated on any chip. This application does not impose any limitation on the form of expression, integration method, circuit type, chip type, etc. of the sampling module 111 and the computing control module 112.

[0040] In some embodiments, the battery 10 may be a lithium cobalt oxide battery, a ternary lithium battery, a lithium iron phosphate battery, etc. The present application does not impose any limitation on the type of the battery 10 .

[0041] In some embodiments, the battery 10 is a lithium iron phosphate battery.

[0042] See also Figure 3 , Figure 3 The schematic diagram of the battery cell module 12 provided in the present application is as follows. The battery cell module 12 includes a housing 121 , a positive electrode tab 122 , a negative electrode tab 123 , a reference electrode tab 124 , and an electrolyte 125 .

[0043] The electrolyte 125 is contained in the housing 121, and the positive electrode tab 122, the negative electrode tab 123, and the reference electrode tab 124 are at least partially immersed in the electrolyte 125, and the positive electrode tab 122, the negative electrode tab 123, and the reference electrode tab 124 are partially extended out of one side of the housing 121. The positive electrode tab 122, the negative electrode tab 123, and the reference electrode tab 124 are spaced apart from each other.

[0044] In some embodiments, the positive electrode tab 122, the negative electrode tab 123, and the reference electrode tab 124 may be disposed on the same side of the housing 121, or may be disposed on different sides. For example, the positive electrode tab 122, the negative electrode tab 123, and the reference electrode tab 124 may all extend from the first side 1211 of the housing 121, or the positive electrode tab 122 and the negative electrode tab 123 extend from the first side 1211 of the housing 121, and the reference electrode tab 124 extends from the second side 1212 adjacent to the first side 1211. The present application does not impose any limitation on the relative positions of the positive electrode tab 122, the negative electrode tab 123, and the reference electrode tab 124.

[0045] The positive electrode tab 122 is connected to the positive electrode of the cell module 12, the negative electrode tab 123 is connected to the negative electrode of the cell module 12, and the reference electrode tab 123 is connected to the reference electrode of the cell module 12. The reference electrode tab 124 is led out from between the positive electrode and the negative electrode.

[0046] In some embodiments, the reference electrode can be in various strip shapes, such as cylindrical or thin sheet shapes. The length and width of the reference electrode can be determined according to the battery model. For example, the width of the reference electrode is 3-6 mm. The positive electrode, the reference electrode, and the negative electrode are arranged in sequence, and an isolation membrane is provided between the positive electrode and the reference electrode, and between the negative electrode and the reference electrode.

[0047] In some embodiments, the reference electrode can be an Ag / AgCl electrode, a saturated calomel electrode, a mercury oxide electrode, a mercurous sulfate electrode, etc. The material and components of the reference electrode can be flexibly configured according to the type of electrolyte 125, and this application does not impose any limitation on this.

[0048] Among them, the reference electrode has a stable and constant potential. The reason is that, on the one hand, during the charge and discharge process of the battery, the electrode reaction in which the reference electrode participates is reversible and can reach equilibrium relatively quickly, so the potential of the reference electrode can remain stable and constant. On the other hand, during the charge and discharge process of the battery, almost no current flows through the reference electrode, so the potential fluctuation caused by current polarization is small, so the potential of the reference electrode can remain stable and constant.

[0049] Since the OCV of the battery is greatly affected by the battery's charge and discharge current, temperature, application scenario, and operating conditions, the RSOC of the battery calculated based on OCV (DOD, T) may not be accurate. Therefore, the present application sets a reference electrode in the battery module 12. Since the potential of the reference electrode is relatively stable and constant, the positive electrode potential and / or negative electrode potential of the battery module 12 can be measured and replaced with the original OCV to establish a mapping relationship between the positive electrode potential and / or negative electrode potential of the battery module 12 and DOD, so as to reduce the RSOC calculation error of the battery and improve the precision and accuracy of RSOC. Among them, the positive electrode potential is the voltage between the positive electrode and the reference electrode, and the negative electrode potential is the voltage between the negative electrode and the reference electrode.

[0050] Specifically, see Figure 4 , Figure 4 A flowchart of a method for obtaining the remaining power of a battery provided in the present application. The method for obtaining the remaining power of a battery can be executed by a battery management system 11. The method for obtaining the remaining power of a battery includes a potential parameter determination stage, a modeling stage, and an application stage. The modeling stage specifically includes the following steps: Step S41, collecting multiple current discharge depths of at least one battery cell module 12 and multiple potential parameters corresponding to the multiple current discharge depths during the process of discharging the battery 10 from a discharge depth of 0% to a discharge depth of 100% at multiple preset temperatures.

[0051] Among them, the process of the battery 10 discharging from a discharge depth of 0% to a discharge depth of 100% may include the process of the battery 10 discharging from a charge cut-off state to a discharge cut-off state. Collecting multiple discharge depths of at least one battery cell module 12 and multiple potential parameters corresponding to multiple current discharge depths respectively may include collecting the potential parameters of each battery cell module 12 at every preset discharge depth, thereby obtaining multiple discharge depths and corresponding potential parameters of the battery cell module 12 during the discharge process. For example, during the discharge process of each battery cell module 12, the potential parameters corresponding to the battery cell module 12 may be collected at every 2% discharge depth.

[0052] In some embodiments, when collecting the potential parameters of each battery cell module 12 at every preset discharge depth, the potential parameters can be collected after standing still. For example, the preset discharge depth is 2%, and the discharge of the battery 10 is suspended at every 2% discharge depth, and the battery 10 is allowed to stand still for 2 hours, at which time the potential parameters of the battery 10 are collected. After the collection is completed, the discharge process of the battery 10 is resumed. In this way, the collection stability and accuracy of the potential parameters can be improved.

[0053] Step S42 , establishing a potential parameter-discharge depth matching model of at least one battery cell module 12 at multiple preset temperatures according to multiple current discharge depths of at least one battery cell module 12 and multiple potential parameters corresponding to the multiple current discharge depths.

[0054] Among them, the potential parameter-discharge depth matching model can be obtained by data fitting based on multiple discharge depths and their corresponding multiple potential parameters. In the potential parameter-discharge depth matching model, the mapping relationship between the potential parameter and the discharge depth can be determined according to different multiple fitting methods and fitting functions. For example, the potential parameter and the discharge depth can be linearly correlated, nonlinearly correlated, etc.

[0055] Since the potential parameters corresponding to the same discharge depth of the battery cell module 12 under different temperature conditions are different, it is necessary to establish a potential parameter-discharge depth matching model of the battery cell module 12 at multiple preset temperatures.

[0056] In some embodiments, when at least two battery cell modules 12 are made of the same material and the same type, the potential parameter-discharge depth matching model of one battery cell module 12 can be applicable to the other battery cell modules 12 of the at least two battery cell modules 12 .

[0057] Therefore, the method for obtaining the remaining power of the battery provided in the present application establishes a potential parameter-discharge depth matching model of the battery cell module 12 by obtaining multiple current discharge depths and their corresponding potential parameters during the discharge process of the battery cell module 12. This can reduce the influence of the charge and discharge current, temperature, application scenarios, operating conditions, etc. of the battery 10 on the precision and accuracy of the potential parameter-discharge depth matching model, and can reduce the RSOC calculation error of the battery and improve the precision and accuracy of RSOC.

[0058] In some embodiments, the modeling phase further includes the following steps: Step S43, fitting the potential parameter-discharge depth matching models at more temperatures according to the potential parameter-discharge depth matching models at multiple preset temperatures.

[0059] The following is an example of multiple preset temperatures including 25°C, 30°C, 35°C, and 40°C, where the potential parameter-discharge depth matching model corresponding to each preset temperature is a linear relationship model. However, this application does not impose any restrictions on the specific values ​​of the multiple preset temperatures and the specific types of the potential parameter-discharge depth matching model corresponding to each preset temperature.

[0060] For example, after executing step S42 of the modeling stage at the above multiple preset temperatures, the corresponding potential parameter-discharge depth matching models can be obtained as d1=a1*v+b1, d2=a2*v+b2, d3=a3*v+b3, d4=a4*v+b4, wherein d1, d2, d3, d4 are the discharge depths corresponding to 25°C, 30°C, 35°C, and 40°C, respectively, v is the real-time potential parameter value of the battery cell module 12, a1, a2, a3, a4 are the slope values ​​in the potential parameter-discharge depth matching model at 25°C, 30°C, 35°C, and 40°C, respectively, and b1, b2, b3, b4 are the intercept values ​​in the potential parameter-discharge depth matching model at 25°C, 30°C, 35°C, and 40°C, respectively.

[0061] If it is necessary to obtain the potential parameter-discharge depth matching model corresponding to 27°C, the data can be fitted according to the potential parameter-discharge depth matching model corresponding to 25°C and the potential parameter-discharge depth matching model corresponding to 30°C, that is, the data can be fitted by the potential parameter-discharge depth matching model corresponding to the previous preset temperature and the next preset temperature of the target temperature. Among them, the previous preset temperature can be the maximum preset temperature less than the target temperature, and the next preset temperature can be the minimum preset temperature greater than the target temperature. Specifically, the potential parameter-discharge depth matching model corresponding to 27°C can be expressed as d5=a5*v+b5, wherein a5 can be the arithmetic mean, geometric mean, weighted mean, harmonic mean, etc. of a1 and a2, and b5 can be the arithmetic mean, geometric mean, weighted mean, harmonic mean, etc. of b1 and b2. By analogy, according to the potential parameter-discharge depth matching model at multiple preset temperatures, the potential parameter-discharge depth matching model at more temperatures can be fitted.

[0062] It can be understood that the above fitting process is only for illustration, and the present application does not impose any limitation on the data basis, fitting method, etc. adopted for data fitting.

[0063] Therefore, in the method for obtaining the remaining power of a battery provided in the present application, by using the potential parameter-discharge depth matching model at multiple preset temperatures, the potential parameter-discharge depth matching model under more temperature conditions can be fitted, thereby expanding the applicable temperature range of the potential parameter-discharge depth matching model and improving the compatibility of the potential parameter-discharge depth matching model.

[0064] After the modeling stage is completed, the real-time potential parameters and real-time temperature of the battery cell module 12 can be detected, and the real-time discharge depth of the battery cell module 12 can be obtained according to the corresponding potential parameter-discharge depth matching model at multiple preset temperatures, and then the RSOC of the battery cell module 12 can be calculated, that is, the application stage is executed.

[0065] Specifically, see Figure 5 , Figure 5 Another flow chart of the method for obtaining the remaining power of a battery provided in the present application. The application phase of the method for obtaining the remaining power of a battery specifically includes the following steps: Step S51 , obtaining real-time potential parameters and current temperature of at least one battery cell module 12 during the discharge process.

[0066] In order to determine the real-time discharge depth of the battery cell module 12 , it is necessary to obtain the current temperature of the battery cell module 12 so as to select a potential parameter-discharge depth matching model at a corresponding temperature for application.

[0067] Step S52 , obtaining the real-time discharge depth of at least one battery cell module 12 according to the potential parameter-discharge depth matching model corresponding to at least one battery cell module 12 at the current temperature and the real-time potential parameter.

[0068] The current temperature may be one of a plurality of preset temperatures. In this case, the potential parameter-discharge depth matching model corresponding to the current temperature is the potential parameter-discharge depth matching model at the preset temperature.

[0069] When the current temperature is not any of the multiple preset temperatures, the potential parameter-discharge depth matching model corresponding to the current temperature may be a potential parameter-discharge depth matching model obtained by fitting the potential parameter-discharge depth matching models at multiple preset temperatures. For example, the multiple preset temperatures include 25°C and 30°C, and when the current temperature is 27°C, the potential parameter-discharge depth matching model corresponding to 27°C may be obtained by fitting the potential parameter-discharge depth matching models corresponding to 25°C and 30°C. For the specific fitting basis and fitting method, please refer to the description of step S43, which will not be repeated here.

[0070] Step S53 , obtaining the remaining power of the battery 10 according to the real-time discharge depth of at least one battery cell module 12 .

[0071] Specifically, when the battery 10 includes a plurality of cell modules 12, the remaining power of the battery 10 can be expressed as the minimum remaining power of all cell modules 12. Therefore, after obtaining the real-time discharge depth of at least one cell module 12, the remaining power of at least one cell module 12 can be obtained according to the preset relationship between the real-time discharge depth and the remaining power, and then the remaining power of all cell modules 12 is compared, and the minimum value is selected as the remaining power of the battery 10.

[0072] See also Figure 6 , Figure 6 This is another flow chart of the method for obtaining the remaining power of a battery provided by the present application. Before the modeling stage, the method for obtaining the remaining power of a battery provided by the present application also includes a potential parameter determination stage, which specifically includes the following steps: Step S61, at a plurality of preset temperatures, the battery 10 is discharged from a discharge depth of 0% to a discharge depth of 100%, and a plurality of discharge depths of at least one battery cell module 12 and a plurality of positive electrode potentials and a plurality of negative electrode potentials corresponding thereto are collected.

[0073] Step S62, determining one of the positive electrode potential and the negative electrode potential as a potential parameter according to the change rates of the plurality of positive electrode potentials and the plurality of negative electrode potentials with the corresponding plurality of discharge depths.

[0074] Among them, the positive electrode potential of the battery module 12 can be obtained by measuring the voltage between the positive electrode tab 122 and the reference electrode tab 124, and the negative electrode potential can be obtained by measuring the voltage between the negative electrode tab 123 and the reference electrode tab 124. The change rates of multiple positive electrode potentials and multiple negative electrode potentials with corresponding multiple discharge depths can be expressed as the change of the positive electrode potential and the change of the negative electrode potential within the preset interval of the discharge depth. Among them, the change can be expressed by data such as range, variance, and change amount. For example, the preset interval can be 0% to 100%, and the difference between the positive electrode potential corresponding to the battery cell module 12 when the discharge depth is 0% and the positive electrode potential corresponding to the discharge depth is 100%, that is, the change in the positive electrode potential of the battery cell module 12 within the preset interval can be used as the change rate of multiple positive electrode potentials with the corresponding multiple discharge depths. Similarly, the difference between the negative electrode potential corresponding to the battery cell module 12 when the discharge depth is 0% and the negative electrode potential corresponding to the discharge depth is 100%, that is, the change in the negative electrode potential of the battery cell module 12 within the preset interval can be used as the change rate of multiple negative electrode potentials with the corresponding multiple discharge depths.

[0075] In some embodiments, according to the change rates of the multiple positive electrode potentials and the multiple negative electrode potentials with the corresponding multiple discharge depths, one of the positive electrode potential and the negative electrode potential is determined as the potential parameter. The potential parameter can be determined specifically according to the comparison result between the change rates of the multiple positive electrode potentials with the corresponding multiple discharge depths and the change rates of the multiple negative electrode potentials with the corresponding multiple discharge depths. For example, the larger value of the two can be taken as the potential parameter.

[0076] In some embodiments, the specific type of potential parameter can also be determined based on the stability of the positive electrode potential and the negative electrode potential. For example, the negative electrode potential is less affected by the charge and discharge current, temperature, application scenario, and operating conditions. When the charge and discharge current, temperature, application scenario, and operating conditions change, the negative electrode potential remains basically unchanged. Therefore, the negative electrode potential has strong stability and can be used as a potential parameter.

[0077] The following diagrams and tables describe the steps in the potential parameter determination phase. Figure 7 , Figure 7 A schematic diagram of the potential parameter-discharge depth matching model provided in this application. In the process of the battery cell module 12 discharging from a discharge depth of 0% to a discharge depth of 100%, curve S1 is a curve showing the change of the positive electrode potential with the DOD of the battery cell module 12, and curve S2 is a curve showing the change of the negative electrode potential with the DOD of the battery cell module 12.

[0078] As can be seen from the figure, the positive electrode potential and negative electrode potential curves remain monotonic in the interval of DOD (0%, 100%), that is, the positive electrode potential increases in the interval of DOD (0%, 100%), and the negative electrode potential decreases in the interval of DOD (0%, 100%). However, the change trend of the positive electrode potential in the interval of DOD (0%, 96%) is relatively gentle, that is, the slope of curve S1 in the interval of DOD (0%, 96%) is close to zero, so the interval of (0%, 96%) can be defined as a voltage flat interval. In addition, the change trend of the negative electrode potential in the interval of DOD (0%, 100%) is relatively steep, that is, the slope of curve S2 in the interval of DOD (0%, 96%) is relatively large.

[0079] Here, the rate of change of the potential parameter is taken as the change of the potential parameter divided by the length of the DOD interval. When the DOD is 0%, the initial value of the positive electrode potential is 3400mV, and the initial value of the negative electrode potential is 900mV. When the DOD is 100%, the positive electrode potential cutoff value is 3700mV, and the negative electrode potential cutoff value is 70mV. Therefore, the rate of change of the positive electrode potential can be defined as 300mV / 100%, and the rate of change of the negative electrode potential can be defined as 830mV / 100%. The rate of change of the negative electrode potential is greater than the rate of change of the positive electrode potential, so the negative electrode potential can be used as a potential parameter.

[0080] In some embodiments, in the method for obtaining the remaining power of a battery provided by the present application, the modeling stage further includes: determining the discharge current of the battery 10. In the process of the battery 10 discharging from a discharge depth of 0% to a discharge depth of 100%, the discharge mode may be constant current discharge. The discharge current during the constant current discharge is the discharge current of the battery 10.

[0081] The discharge current of the battery 10 can be determined according to different situations. Figure 8 As shown, determining the discharge current of the battery 10 may specifically include the following steps: Step S81, when the discharge start temperature is a preset temperature, the battery 10 is subjected to constant current discharge with a plurality of preset discharge currents, and a plurality of discharge cut-off temperatures corresponding to the plurality of preset discharge currents are collected when the constant current discharge of the battery 10 is cut off.

[0082] Step S82: determining the discharge current of the battery 10 to be at least one of the corresponding multiple preset discharge currents according to the multiple discharge cut-off temperatures.

[0083] That is, the appropriate discharge current of the battery 10 during the discharge process can be determined by detecting the influence of multiple preset discharge currents on the temperature change of the battery 10. Specifically, one of the multiple preset discharge currents can be determined as the discharge current of the battery 10 according to the difference between the preset temperature of the battery 10 at the beginning of discharge and the discharge cut-off temperature at the end of discharge. In order to reduce the influence of the discharge current on the discharge temperature rise of the battery 10, the preset discharge current corresponding to the temperature rise of the battery 10 less than the preset temperature value can be selected as the discharge current of the battery 10. That is, the preset discharge current corresponding to the difference between the preset temperature of the battery 10 at the beginning of discharge and the discharge cut-off temperature at the end of discharge is less than the preset temperature value is used as the discharge current of the battery 10. In this way, the temperature rise of the battery 10 during the discharge process can be controlled within an acceptable range, thereby reducing the influence of temperature change on the modeling accuracy of the potential parameter-discharge depth matching model.

[0084] For example, Fig. 9 As shown, determining the discharge current of the battery 10 may specifically include the following steps: Step S91, at the same preset temperature, the battery 10 is discharged with a plurality of preset discharge currents, and the initial battery capacity of the battery 10 at the start of discharge and a plurality of discharge cut-off capacities corresponding to the plurality of preset discharge currents at the end of discharge are collected.

[0085] Step S92 , determining that the difference between the initial battery capacity and the discharge cut-off capacity is less than the preset capacity threshold, and the preset discharge current corresponding to the preset capacity threshold is the discharge current of the battery 10 .

[0086] That is, the appropriate discharge current of the battery 10 during the discharge process can be determined by detecting the influence of multiple preset discharge currents on the change of the battery capacity of the battery 10. Specifically, one of the multiple preset discharge currents can be determined as the discharge current of the battery 10 according to the difference between the initial battery capacity of the battery 10 at the beginning of discharge and the discharge cut-off capacity at the end of discharge. In order to reduce the influence of the discharge current on the battery capacity decay of the battery 10, the preset discharge current corresponding to the battery 10 when the battery capacity decay is less than the preset capacity threshold can be selected as the discharge current of the battery 10. That is, the preset discharge current corresponding to the difference between the initial battery capacity of the battery 10 at the beginning of discharge and the discharge cut-off capacity at the end of discharge is less than the preset capacity threshold is used as the discharge current of the battery 10. In this way, the influence of the battery capacity decay on the modeling accuracy of the potential parameter-discharge depth matching model can be reduced.

[0087] For example, Fig.10 As shown, determining the discharge current of the battery 10 may specifically include the following steps: In step S101, the battery 10 is discharged with a plurality of preset discharge currents. At each preset discharge depth, a plurality of voltage change rates of the battery 10 and a plurality of time durations for each voltage change rate to decrease to a preset change rate are collected respectively.

[0088] Step S102 : determining at least one of a plurality of preset discharge currents as the discharge current of the battery 10 according to a plurality of time durations.

[0089] That is, the appropriate discharge current of the battery 10 during the discharge process can be determined by detecting the influence of multiple preset discharge currents on the voltage stability of the battery 10. Specifically, the voltage stability of the battery 10 may include one or more of the stability of the positive electrode potential of the battery 10, the stability of the negative electrode potential, and the stability of OCV.

[0090] During the constant current discharge of the battery 10, one of the multiple preset discharge currents can be determined as the discharge current of the battery 10 according to the multiple voltage change rates of the battery 10 and the multiple time durations for each voltage change rate to be reduced to the preset change rate. In order to reduce the influence of the discharge current on the voltage stability of the battery 10, the preset discharge current corresponding to the higher voltage stability of the battery 10 can be selected as the discharge current of the battery 10.

[0091] In some embodiments, the voltage stability of the battery 10 can be determined based on the voltage change rate of the battery cell module 12 or the duration that the battery 10 is in a static state. Specifically, if the voltage change rate of the battery cell module 12 is less than a preset change rate, for example, 4 μV / s, it can be determined that the voltage of the battery 10 is stable. Alternatively, if the duration that the battery 10 is in a static state is greater than a preset static duration, it can be determined that the voltage of the battery 10 is stable. Among them, when the current of the battery 10 is less than a preset static current, for example, 10 mA, it can be determined that the battery 10 is in a static state, and the preset static duration can be pre-set according to actual conditions, for example, 5 hours.

[0092] In other embodiments, the voltage stability of the battery 10 can be determined based on the multiple durations for each voltage change rate to be reduced to a preset change rate. For example, if the preset discharge depth is 2%, in the process of the battery 10 discharging from a discharge depth of 0% to a discharge depth of 100%, a total of 50 voltage change rates and the corresponding 50 durations for the voltage change rates to be reduced to the preset change rate can be measured. Here, the preset change rate can be 10mV / s. If the durations for the 50 voltage change rates to be reduced to the preset change rate are all less than the preset duration, the corresponding preset discharge current can be used as the discharge current of the battery 10. Here, the preset duration can be 2 hours.

[0093] In some embodiments, the discharge current of the battery 10 may be 0.05C-0.1C.

[0094] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application and are not intended to be limiting of the present application. As long as they are within the spirit and scope of the present application, appropriate changes and modifications to the above embodiments are within the scope of protection claimed in the present application.

Claims

1. A method for obtaining the remaining power of a battery, characterized in that: The application phase includes: Obtaining real-time potential parameters and current temperature of at least one battery cell module in the battery during discharge; Obtaining a real-time discharge depth of the at least one battery cell module according to a potential parameter-discharge depth matching model corresponding to the at least one battery cell module at a current temperature and the real-time potential parameter; The remaining power of the battery is obtained according to the real-time discharge depth of the at least one battery cell module.

2. The method for obtaining the remaining power of a battery according to claim 1, wherein: Before the application phase, the method further includes a modeling phase, which includes: Under multiple preset temperatures, during the process of discharging the battery from a discharge depth of 0% to a discharge depth of 100%, multiple discharge depths of at least one battery cell module in the battery and multiple potential parameters corresponding to the multiple discharge depths are collected, wherein each of the battery cell modules includes a reference electrode, and the potential parameters include a positive electrode potential between a positive electrode in the battery cell module and the reference electrode, and / or a negative electrode potential between a negative electrode and the reference electrode; A potential parameter-discharge depth matching model of the battery at the multiple preset temperatures is established according to the multiple discharge depths of the at least one battery cell module and the multiple potential parameters corresponding to the multiple discharge depths.

3. The method for obtaining the remaining power of a battery as claimed in claim 2, characterized in that: Before the modeling stage, the method further includes a potential parameter determination stage, which includes: At a preset temperature, during the process of discharging the battery from a discharge depth of 0% to a discharge depth of 100%, collecting a plurality of current discharge depths of at least one battery cell module in the battery, a plurality of positive electrode potentials corresponding to the plurality of current discharge depths, and a plurality of negative electrode potentials corresponding to the plurality of current discharge depths; According to the change rates of the plurality of positive electrode potentials and the plurality of negative electrode potentials with the corresponding plurality of current discharge depths, one of the plurality of positive electrode potentials and the plurality of negative electrode potentials is determined as the potential parameter.

4. The method for obtaining the remaining power of a battery as claimed in claim 3, characterized in that: The determining one of the plurality of positive electrode potentials and the plurality of negative electrode potentials as the potential parameter according to the change rates of the plurality of positive electrode potentials and the plurality of negative electrode potentials with the corresponding plurality of current discharge depths, comprises: The highest one of the change rates of the plurality of positive electrode potentials and the plurality of negative electrode potentials with the corresponding plurality of current discharge depths is determined as the potential parameter.

5. The method for obtaining the remaining power of a battery as claimed in claim 2, characterized in that: The potential parameter is the cathode potential between the cathode and the reference electrode.

6. The method for obtaining the remaining power of a battery as claimed in claim 2, characterized in that: The modeling phase also includes: A discharge current of the battery is determined.

7. The method for obtaining the remaining power of a battery as claimed in claim 6, characterized in that: The determining the discharge current of the battery comprises: When the discharge starting temperature is the preset temperature, the battery is subjected to constant current discharge with multiple preset discharge currents, and multiple discharge cut-off temperatures corresponding to the multiple preset discharge currents are collected when the constant current discharge of the battery is cut off; It is determined that the preset discharge current corresponding to the difference between the preset temperature and the multiple discharge cut-off temperatures being less than a preset temperature threshold is the discharge current of the battery.

8. The method for obtaining the remaining power of a battery as claimed in claim 6, characterized in that: The determining the discharge current of the battery comprises: At the same preset temperature, the battery is discharged with multiple preset discharge currents, and the initial battery capacity of the battery at the start of discharge and multiple discharge cut-off capacities corresponding to the multiple preset discharge currents at the end of discharge are collected; The preset discharge current corresponding to the difference between the initial battery capacity and the discharge cut-off capacity being determined to be less than a preset capacity threshold is the discharge current of the battery.

9. The method for obtaining the remaining power of a battery as claimed in claim 6, characterized in that: The determining the discharge current of the battery comprises: At the same preset temperature, the battery is discharged with multiple preset discharge currents, and at each preset discharge depth, multiple voltage change rates of the battery and multiple durations for each voltage change rate to decrease to a preset change rate are collected respectively; At least one of the plurality of preset discharge currents is determined according to the plurality of time periods as a discharge current of the battery.

10. The method for obtaining the remaining power of a battery according to claim 1, characterized in that: Obtaining the remaining power of the battery according to the real-time discharge depth of the at least one battery cell module, including: Obtaining the remaining power of each of the battery modules according to the real-time discharge depth of the at least one battery module; The remaining power of the battery cell module with the lowest remaining power is used as the remaining power of the battery.

11. The method for obtaining the remaining power of a battery according to claim 10, wherein: According to the real-time discharge depth of the at least one battery cell module, the remaining power of each battery cell module is obtained, including: According to a preset relationship between the discharge depth and the remaining power, the remaining power is obtained from the real-time discharge depth; Wherein, the preset relationship includes: the sum of the discharge depth and the remaining power is 1.

12. A battery, characterized in that: It includes at least one battery cell module and a battery management system, each of the battery cell modules includes a positive electrode, a reference electrode and a negative electrode, the reference electrode has a constant potential, the battery management system is electrically connected to the battery cell module, and the battery management system is used to execute the remaining power acquisition method of the battery as described in any one of claims 1 to 11.

13. The battery according to claim 12, characterized in that The battery management system comprises a negative electrode potential sampling circuit, which is electrically connected to a reference electrode and a negative electrode in the at least one battery cell module and is used to collect the negative electrode potential of the at least one battery cell module.

14. The battery according to claim 13, characterized in that The battery is a lithium iron phosphate battery.

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