CN115128470A - Estimation method and device for energy efficiency of battery pack and electronic equipment - Google Patents

Estimation method and device for energy efficiency of battery pack and electronic equipment Download PDF

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CN115128470A
CN115128470A CN202210761367.XA CN202210761367A CN115128470A CN 115128470 A CN115128470 A CN 115128470A CN 202210761367 A CN202210761367 A CN 202210761367A CN 115128470 A CN115128470 A CN 115128470A
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battery pack
energy
battery
calculating
difference
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许鑫
鞠靓辰
刘程
其他发明人请求不公开姓名
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Svolt Energy Technology Co Ltd
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Svolt Energy Technology Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/389—Measuring internal impedance, internal conductance or related variables
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/396—Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

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Abstract

The invention discloses a method for estimating energy efficiency of a battery pack, which comprises the following steps: calculating first actual available energy of the battery pack based on influence factors causing energy loss of the battery pack in an integration process, wherein the integration process is a process of integrating single battery cells into the battery pack, and the influence factors at least comprise one of series battery cell energy deviation, a battery pack SOC usable interval, battery cell SOC difference in the battery pack, sensor precision and battery pack internal resistance; adjusting the first actual available energy based on energy loss caused by the difference of the working temperature and environment of the battery pack and energy loss caused by storage and discharge to obtain second actual available energy of the battery pack; and calculating the ratio of the second practical available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack. The technical scheme provided by the invention further improves the accuracy of the energy efficiency estimation of the battery pack.

Description

Estimation method and device for energy efficiency of battery pack and electronic equipment
Technical Field
The invention relates to the field of new energy lithium batteries, in particular to a method and a device for estimating energy efficiency of a battery pack and electronic equipment.
Background
Along with the large-scale application of lithium batteries, especially the vigorous popularization of new energy automobiles, the cost of raw materials is greatly increased, the cost pressure of enterprises is higher and higher, and higher requirements are provided for the integration efficiency from the battery core to the battery pack. The integration efficiency includes mass energy density efficiency, volumetric energy density efficiency, energy efficiency, capacity efficiency, and the like. Energy efficiency is particularly emphasized, and since the energy efficiency is directly related to the cost of the system and the driving range of the whole vehicle (the energy efficiency is the ratio of the lost energy to the theoretical energy, which is excluded by the whole battery pack after the battery cell is integrated into the battery pack), accurate estimation of the energy efficiency of the battery pack is of great significance to battery production enterprises.
However, in the prior art, when estimating the energy efficiency or the capacity efficiency of the battery, research is focused on the battery pack, and the energy fluctuation generated in the production process of the battery pack cannot be considered, for example, a method for estimating the capacity loss based on the temperature difference and the pressure difference of the battery pack after the battery pack is packed is disclosed in patent document (CN 110031769A). Therefore, how to further improve the accuracy of estimating the energy efficiency of the battery pack is an urgent problem to be solved.
Disclosure of Invention
In view of this, the embodiment of the present invention provides a method and an apparatus for estimating energy efficiency of a battery pack, and an electronic device, so as to further improve accuracy of estimating energy efficiency of a battery pack.
According to a first aspect, an embodiment of the present invention provides a method for estimating energy efficiency of a battery pack, the method including: calculating first actual available energy of the battery pack based on influence factors causing energy loss of the battery pack in an integration process, wherein the integration process is a process of integrating single battery cells into the battery pack, and the influence factors at least comprise one of series battery cell energy deviation, a battery pack SOC (state of charge) usable interval, battery cell SOC difference in the battery pack, sensor precision and battery pack internal resistance; adjusting the first actual available energy based on energy loss caused by working temperature environment difference of the battery pack and energy loss caused by storage discharge to obtain second actual available energy of the battery pack, wherein the working temperature environment difference is the difference between the working temperature environment of the battery cell in the battery pack and the working temperature environment of the single battery cell; and calculating the ratio of the second practical available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack.
Optionally, the calculating the first actual available energy of the battery pack based on the influencing factors causing the energy loss of the battery pack in the integration process includes: calculating theoretical energy of the battery pack based on the battery cell integrated structure; calculating a corresponding loss energy value of the battery pack or a proportionality coefficient of residual energy of the battery pack after the energy is lost through the influence factors; and determining the first actual available energy from the theoretical energy of the battery pack through the proportionality coefficient and the loss energy value.
Optionally, the calculating theoretical energy of the battery pack based on the cell integrated structure includes: acquiring the serial quantity and the parallel quantity of the battery cells in the battery pack according to the battery cell integrated structure; and obtaining the theoretical energy of the battery pack by the product of the serial number, the parallel number, the nominal capacity of the single battery cell and the nominal voltage of the single battery cell.
Optionally, calculating a proportionality coefficient of remaining energy of the battery pack after energy loss through the influencing factors includes: calculating a first ratio of minimum single cell electric core energy to nominal single cell electric core energy in the battery pack to obtain a first ratio coefficient for representing the energy deviation of the series-connected electric cores; calculating a difference value between the use upper limit and the use lower limit of the SOC of the battery pack to obtain a second proportionality coefficient for representing the SOC usable interval of the battery pack; calculating a second ratio of the cell energy difference to the minimum single cell energy, calculating a product of the second ratio and the evolution of the parallel quantity, and then negating the calculation result in a percentage interval to obtain a third proportionality coefficient for representing the cell SOC difference in the battery pack, wherein the cell energy difference comprises an energy difference between cells caused by capacity grading equipment precision difference and an energy difference caused by self-discharge difference between the cells when an integration process is executed; acquiring sampling energy loss of a sensor error, calculating a third ratio of the sampling energy loss to minimum monomer battery core energy, and then negating the third ratio in a percentage interval to obtain a fourth proportionality coefficient for representing the accuracy of the sensor; wherein the first scaling factor, the second scaling factor, the third scaling factor, and the fourth scaling factor all belong to the scaling factor.
Optionally, calculating the corresponding energy loss value of the battery pack through the influencing factors includes: and calculating the energy consumption of the electrical connection mechanism in the battery pack based on the product of the square of the nominal current of the battery pack and the internal resistance of the battery pack, and taking the energy consumption of the electrical connection mechanism in the battery pack as the loss energy value of the battery pack.
Optionally, the determining the first actual available energy from the theoretical energy of the battery pack through the scaling factor and the loss energy value includes: calculating the product of the theoretical energy of the battery pack and the first proportionality coefficient, the second proportionality coefficient, the third proportionality coefficient and the fourth proportionality coefficient to obtain the intermediate quantity of the residual energy; and calculating the difference value between the intermediate quantity of the residual energy and the energy consumption of the electrical connection mechanism in the battery pack to obtain the first actual available energy.
Optionally, the method further comprises: calculating the ratio of the second actual available energy to the nominal voltage of the single battery cell and the serial number to obtain the actual capacity of the battery pack; and calculating the ratio of the actual capacity of the battery pack to the nominal capacity of the single battery cells and the parallel connection quantity to obtain the capacity efficiency of the battery pack.
According to a second aspect, an embodiment of the present invention provides an apparatus for estimating energy efficiency of a battery pack, the apparatus including: the first loss unit is used for calculating first actual available energy of the battery pack based on influence factors causing energy loss of the battery pack in an integration process, wherein the integration process is a process of integrating single battery cells into the battery pack, and the influence factors at least comprise one of series battery cell energy deviation, a battery pack SOC (state of charge) usable interval, battery cell SOC difference in the battery pack, sensor precision and battery pack internal resistance; the second loss unit is used for adjusting the first actual available energy based on energy loss caused by the working temperature environment difference of the battery pack and energy loss caused by storage discharge to obtain second actual available energy of the battery pack, wherein the working temperature environment difference is the difference between the working temperature environment of the battery cell in the battery pack and the working temperature environment of the single battery cell; and the energy efficiency unit is used for calculating the ratio of the second actual available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack.
According to a third aspect, an embodiment of the present invention provides an electronic device, including: a memory and a processor, the memory and the processor being communicatively coupled to each other, the memory having stored therein computer instructions, and the processor performing the method of the first aspect, or any one of the optional embodiments of the first aspect, by executing the computer instructions.
According to a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores computer instructions for causing a computer to thereby perform the method of the first aspect, or any one of the optional implementation manners of the first aspect.
The technical scheme provided by the application has the following advantages:
according to the technical scheme, the energy loss of the battery pack is estimated through three main stages, namely a battery core-to-battery pack integration stage, a battery pack working temperature environment difference and a battery pack matching-to-battery system storage stage. Compared with the prior art, the method fully considers the influence of the assembly time difference from the battery core to the system, the topological connection structure difference of the system and the internal electrical design difference of the battery system on the energy efficiency. Thereby improving the accuracy of the energy efficiency estimation of the battery pack. In the embodiment of the invention, the influence factors causing the energy loss of the battery pack in the integration process are specifically introduced, the influence factors at least comprise one of the energy deviation of the series-connected battery cells, the SOC usable interval of the battery pack, the SOC difference of the battery cells in the battery pack, the precision of the sensor and the internal resistance of the battery pack, the influence factors considering the energy loss are more comprehensive, and the first actual available energy is comprehensively determined from the theoretical energy of the battery pack. And then, considering energy loss caused by the difference between the working temperature environment of the battery core in the battery pack and the working temperature environment of the single battery core and energy loss caused by self-discharge of the battery pack storage, and further re-determining the residual energy of the battery pack from the first actual available energy to obtain second actual available energy. And finally, calculating the ratio of the second actual available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack, and further improving the accuracy of estimating the energy efficiency of the battery pack.
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The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:
FIG. 1 is a schematic diagram illustrating the steps of a method for estimating energy efficiency of a battery pack according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram illustrating an apparatus for estimating energy efficiency of a battery pack according to an embodiment of the present invention;
fig. 3 shows a schematic structural diagram of an electronic device in an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Referring to fig. 1, in one embodiment, a method for estimating energy efficiency of a battery pack includes the following steps:
step S101: calculating first actual available energy of the battery pack based on influence factors causing energy loss of the battery pack in an integration process, wherein the integration process is a process of integrating single battery cells into the battery pack, and the influence factors at least comprise one of series battery cell energy deviation, a battery pack SOC usable interval, battery cell SOC difference in the battery pack, sensor precision and battery pack internal resistance.
Step S102: adjusting the first actual available energy based on energy loss caused by working temperature environment difference of the battery pack and energy loss caused by storage discharge to obtain second actual available energy of the battery pack, wherein the working temperature environment difference is the difference between the working temperature environment of the battery cell in the battery pack and the working temperature environment of the single battery cell;
step S103: and calculating the ratio of the second practical available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack.
Specifically, when estimating the energy efficiency of the battery pack, the embodiments of the present invention fully consider the influence of the assembly time difference from the battery core to the system, the difference of the topological connection structure of the system, and the difference of the internal electrical design of the battery system on the energy efficiency. Therefore, influence factors causing energy loss of the battery pack in the integration process are introduced, and the influence factors at least comprise one of series battery cell energy deviation, a battery pack SOC usable interval, battery cell SOC difference in the battery pack, sensor precision and battery pack internal resistance. And determining the first actual available energy remaining in the battery pack during the integration phase after the energy loss is determined from the theoretical energy of the battery pack by the above influencing factors. After the battery packaging bag is finished, energy loss caused by the difference between the working temperature environment of the battery core in the battery bag and the working temperature environment of the single battery core and energy loss caused by self-discharge of the battery bag storage are also considered, and then the remaining energy of the battery bag is determined again from the first actual available energy to obtain second actual available energy. And finally, calculating the ratio of the second actual available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack.
Specifically, the specific explanation for the above-described influencing factors is as follows:
according to the principle that the battery packs are connected in series by the battery cells with the same capacity, the capacity of the battery is unchanged, the capacity of the battery cells connected in parallel is increased, and the capacity of the battery cells connected in series with different capacities is reduced, the situation that the energy deviation of the battery cells connected in series occurs due to the series connection structure of the battery cells in the battery packs, and the deviation corresponds to a part which cannot be utilized in actual use, in other words, the part is an energy loss part, so in the embodiment, the energy deviation of the battery cells connected in series in the production process of the battery is utilized to calculate a part of energy loss. In the second aspect, when the battery pack is produced, a battery enterprise does not normally fully charge the battery in an actual scene in order to consider the use safety of the battery, so that an SOC usable interval is defined, and energy loss is caused by an unusable part, and a part of energy loss is calculated through the SOC usable interval of the battery pack based on the energy loss. In the third aspect, because the individual battery cells in the battery pack have differences, the SOC of each battery cell is not completely the same, and there are a lot of battery cells, and the SOC difference may cause that the battery cells which are fully charged and discharged in the battery pack are not the same battery cell, thereby causing energy loss. Based on this, the embodiment of the invention calculates a part of energy loss by calculating the SOC difference of the battery cells in the battery pack. In the fourth aspect, in the battery production process, acquisition errors exist in the sensor precision for acquiring parameters such as voltage, current and resistance, and part of energy loss can be caused by the errors of parameter acquisition. In the fifth aspect, after the battery pack is packaged, the internal resistance of the battery pack is added besides the internal resistance of the single battery core, and the internal resistance of the battery pack often causes heat release of the battery pack to cause energy loss, so that the energy loss is counted based on the internal resistance of the battery pack, and the accuracy of energy efficiency estimation is further improved. In the embodiment, the specific algorithm of the loss energy value is the product of the square of the nominal current of the battery pack and the internal resistance of the battery pack, and then the product is multiplied by the discharge time, namely the energy consumption of the electrical connection mechanism in the battery pack.
Specifically, in an embodiment, the step S101 specifically includes the following steps:
the method comprises the following steps: and calculating the theoretical energy of the battery pack based on the battery cell integrated structure.
Step two: and calculating the corresponding loss energy value of the battery pack or the proportionality coefficient of the residual energy of the battery pack after the energy is lost through the influence factors.
Step three: the first actual available energy is determined from the theoretical energy of the battery pack by the scaling factor and the loss energy value.
Specifically, after obtaining the influence factors such as "series cell energy deviation, cell pack SOC usable interval, cell SOC difference in the cell pack, sensor accuracy, and cell pack internal resistance", a proportional coefficient of the remaining energy of the battery after the energy loss value, which is related to the influence factors, to the theoretical energy may be calculated according to the influence factors, or the energy loss value directly caused by the influence factors may be directly calculated. Therefore, the first practical available energy can be determined from the theoretical energy of the battery pack by utilizing the proportionality coefficient and the lost energy value. In addition, in this embodiment, the theoretical energy of the battery pack is different due to different battery pack integration structures (the number of battery cells, the serial-parallel connection manner), so that the accurate theoretical energy of the battery pack needs to be calculated based on the battery pack integration structures, and the accuracy of the calculation result of the first actual available energy is further guaranteed.
Specifically, in an embodiment, the step one specifically includes the following steps:
step four: and acquiring the serial quantity and the parallel quantity of the battery cells in the battery pack according to the battery cell integrated structure.
Step five: and obtaining the theoretical energy of the battery pack by the product of the serial number, the parallel number, the nominal capacity of the single battery cell and the nominal voltage of the single battery cell.
Specifically, in this embodiment, first, the number of the series cells and the number of the parallel cells in the battery pack are obtained according to the cell integration structure in the battery pack integration process, then, the theoretical energy value of the single cell is obtained according to the product of the nominal capacity of the single cell and the nominal voltage of the single cell, and then, the product of the theoretical energy value of the single cell and the product of the series number and the parallel number is calculated to obtain the theoretical maximum energy value of the whole battery pack, that is, the theoretical energy of the battery pack.
Specifically, in an embodiment, the second step specifically includes the following steps:
the scaling factor specifically includes a first scaling factor, a second scaling factor, a third scaling factor and a fourth scaling factor, and the calculation method is as follows:
1. and calculating a first ratio of the minimum single cell energy in the battery pack to the nominal single cell energy to obtain a first ratio coefficient for representing the energy deviation of the series cells.
In particular, f 1 ＝E min /E n . Wherein E min Refers to the energy of the smallest cell used in the battery pack, E n Is the nominal energy of the single battery cell, and if the minimum energy of the battery cell is the nominal energy of the battery cell, the first proportionality coefficient f 1 Has a value of 1.
2. And calculating a difference value between the use upper limit and the use lower limit of the SOC of the battery pack to obtain a second proportionality coefficient for representing the SOC usable interval of the battery pack.
Specifically, in this embodiment, the difference between the SOC usable interval of the battery pack, that is, the upper usable limit and the lower usable limit of the battery preset by the battery enterprise, corresponds to the second proportionality coefficient f 2 . Multiplying f by the theoretical energy of the battery pack 2 And obtaining the remaining usable energy value of the battery pack after the energy loss is caused by the unusable interval of the SOC of the battery pack.
3. And calculating a second ratio of the cell energy difference to the minimum single cell energy, calculating a product of the second ratio and the evolution of the parallel quantity, and then negating the calculation result in a percentage interval to obtain a third proportionality coefficient for representing the cell SOC difference in the battery pack, wherein the cell energy difference comprises the energy difference between the cells caused by the capacity grading equipment precision difference and the energy difference caused by the self-discharge difference between the cells when the integration process is executed.
Specifically, considering the difference between the SOC of each cell in the battery pack, the cells charged and discharged in the battery pack may not be the same cell, thereby causing energy loss, so as to calculate the energy loss by counting the difference between the SOC of each cell. Can be used for dredgingThe method is realized by the following steps: thereby at electric core partial volume back, thereby save according to the storage time that obtains the battery package of setting for from electric core to module assembly, then carry out standard discharge to each electric core, obtain the SOC difference of each electric core according to the result of discharging, and then calculate the energy difference. In this embodiment, in order to save the process of cell discharging and further improve the speed of energy loss estimation, a method for calculating energy loss based on the difference between the SOCs of the cells is additionally provided: energy difference delta E between battery cores caused by precision difference of collecting capacity grading equipment eqi And the energy difference delta E caused by the self-discharge difference between the battery cores in the time from the battery core offline to the assembly to the module is collected sdc Then, the third proportionality coefficient f is calculated according to the following formula 3
Figure BDA0003721153120000091
In the formula, C min Is the minimum capacitance, V, of a single cell in a battery pack n Is the nominal voltage, C min *V n The minimum individual cell energy is represented, P is the number of parallel cells, and this embodiment is obtained based on statistical experiments in battery production, and the more parallel cells are, the larger the SOC difference is, and the more serious the energy loss is, thereby obtaining the third proportionality coefficient expression.
4. And acquiring sampling energy loss of the sensor error, calculating a third ratio of the sampling energy loss to the minimum single battery cell energy, and then inverting the third ratio in a percentage interval to obtain a fourth proportionality coefficient for representing the accuracy of the sensor.
Specifically, the fourth proportionality coefficient f calculated from the sensor accuracy 4 ＝1-ΔE sensor /(C min *V n ). Energy loss due to charging failure to fill and discharging failure to reach true cut-off voltage due to sampling error, f 4 The proportion of energy remaining in the individual cells after energy loss is characterized. Delta E sensir Is the loss of sampling energy due to sensor error, which can be obtained by high-precision measurementAnd can also be obtained by theoretical analysis. C min *V n The minimum individual cell energy is represented, where the minimum individual cell energy is used instead of the nominal individual cell energy as the denominator, with reference to the short plate effect, the cell of minimum energy determines the energy of the entire battery pack.
Specifically, in an embodiment, the step three specifically includes the following steps:
step six: calculating the product of the theoretical energy of the battery pack and a first proportional coefficient, a second proportional coefficient, a third proportional coefficient and a fourth proportional coefficient to obtain the intermediate quantity of the residual energy;
step seven: and calculating the difference between the intermediate quantity of the residual energy and the energy consumption of the electrical connection mechanism in the battery pack to obtain first actual available energy.
Based on the above steps, the proportionality coefficient and the loss energy value are obtained, so that the first actual available energy representing the remaining available energy at the stage of battery pack production after the energy is lost can be accurately calculated, and the formula is as follows:
E 1 ＝E t *f 1 *f 2 *f 3 *f 4 -E sys
wherein E is 1 For the first practically available energy, E t Is the theoretical energy of the battery pack, E sys Is the energy consumption of the electrical connection mechanism within the battery pack.
Specifically, in the embodiment of the present invention, after the module is assembled to obtain the battery pack, the irreversible energy loss caused by the storage reason in the process from the assembly of the module to the assembly of the battery system is generally obtained according to the storage performance characteristics of the battery cell, and the storage proportionality coefficient determined based on the storage discharge reason in this embodiment is f 5 . Because the heat dissipation boundary of the battery system and the independent battery cell is different in the charging and discharging process, the heat dissipation of the battery pack is poor, so that the working temperature environment of the battery cell in the battery pack is different from the working temperature environment of the single battery cell, and the energy efficiency of the system is also influenced by the difference. The temperature proportionality coefficient obtained based on the energy retention capacity of the battery cell in different temperature environments is f 6 Usually obtained by table lookup, f 6 It may be greater than 1 and may be greater than 1,and may be less than 1. Based on this, after obtaining the first actually available energy, the second actually available energy E real The calculation formula of (a) is as follows:
E real ＝E1*f 5 *f 6
specifically, in an embodiment, the method for estimating energy efficiency of a battery pack according to an embodiment of the present invention further includes the following steps:
step eight: and calculating the ratio of the second actual available energy to the nominal voltage and the series number of the single battery cells to obtain the actual capacity of the battery pack.
Step nine: and calculating the ratio of the actual capacity of the battery pack to the nominal capacity and the parallel connection quantity of the single battery cores to obtain the capacity efficiency of the battery pack.
Specifically, the embodiment of the present invention may further calculate the capacity efficiency of the battery pack based on the second actual available energy calculated in the above step. The capacity efficiency is calculated with the second actually available energy with higher accuracy, and the accuracy of the capacity efficiency can be further improved. Wherein the actual capacity C of the battery pack is calculated real The following formula
C real ＝E real /(V n *S)。
Wherein S is the number of the cell strings in the battery pack, V n The capacity C of the battery pack actually available can be obtained only by calculating the ratio of the second actually available energy to the nominal voltage of the single battery cell and the serial number of the single battery cell, and the capacity C of the battery pack actually available can be obtained by calculating the ratio of the second actually available energy to the nominal voltage of the single battery cell and the serial number real . And then calculating the product of the nominal capacity of the single battery cell and the parallel number of the battery cells to obtain the capacity of the battery pack theoretically. Finally, the actually available capacity C of the battery pack is calculated real And the ratio of the capacity of the battery pack to the theoretical capacity of the battery pack can obtain the capacity efficiency of the battery pack.
Specifically, in one embodiment, the energy efficiencies of the four systems of the battery pack are shown in the following table:
battery pack E t . f1 f2 f3 f4 Esys f5 f6 Energy efficiency
A 34.61 1 1 0.9927 0.998 0.166 0.997 0.997 98.00％
B 66.56 1 1 0.9897 0.998 0.878 0.997 0.997 96.87％
C 75.37 1 1 0.995 0.998 0.603 0.9958 0.995 97.60％
D 63.59 1 1 0.995 0.998 0.572 0.9958 0.995 97.50％
Through the steps, according to the technical scheme provided by the application, the energy loss of the battery pack is estimated through two stages, namely the battery core-battery pack integration stage and the battery pack assembly stage of the battery system. Compared with the prior art, the method fully considers the influence of the assembly time difference from the battery core to the system, the topological connection structure difference of the system and the internal electrical design difference of the battery system on the energy efficiency. Thereby improving the accuracy of the energy efficiency estimation of the battery pack. In the embodiment of the invention, influence factors causing energy loss of the battery pack in the integration process are specifically introduced, the influence factors at least comprise one of series battery cell energy deviation, a battery pack SOC usable interval, battery cell SOC difference in the battery pack, sensor precision and battery pack internal resistance, the influence factors considering the energy loss are more comprehensive, and the first actual usable energy without loss is comprehensively determined from the theoretical energy of the battery pack. And then, considering energy loss caused by the difference between the working temperature environment of the battery core in the battery pack and the working temperature environment of the single battery core and energy loss caused by self-discharge of the battery pack storage, and further re-determining the residual energy of the battery pack from the first actual available energy to obtain second actual available energy. And finally, calculating the ratio of the second actual available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack, and further improving the accuracy of estimating the energy efficiency of the battery pack.
As shown in fig. 2, the present embodiment also provides an apparatus for estimating energy efficiency of a battery pack, including:
the first loss unit 101 is configured to calculate a first actual available energy of the battery pack based on an influence factor causing energy loss of the battery pack in an integration process, where the integration process is a process of integrating a single battery cell into the battery pack, and the influence factor at least includes one of a series battery cell energy deviation, a battery pack SOC usable interval, a battery cell SOC difference in the battery pack, sensor accuracy, and a battery pack internal resistance. For details, refer to the related description of step S101 in the above method embodiment, and no further description is provided here.
The second loss unit 102 adjusts the first actual available energy based on energy loss caused by ambient temperature and storage discharge during storage of the battery pack, to obtain a second actual available energy of the battery pack. For details, refer to the related description of step S102 in the above method embodiment, and no further description is provided here.
And the energy efficiency unit 103 calculates a ratio of the second actual available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack. For details, refer to the related description of step S103 in the above method embodiment, and no further description is provided here.
The device for estimating the energy efficiency of the battery pack according to the embodiment of the present invention is configured to execute the method for estimating the energy efficiency of the battery pack according to the embodiment, and the implementation manner and the principle thereof are the same, and details are referred to the related description of the method embodiment and are not repeated.
Through the cooperation of the above components, the technical scheme provided by the application estimates the energy loss of the battery pack through two stages, namely, the integration stage from the battery core to the battery pack and the storage stage from the battery pack to the battery system. Compared with the prior art, the method fully considers the influence of the assembly time difference from the battery core to the system, the topological connection structure difference of the system and the internal electrical design difference of the battery system on the energy efficiency. Thereby improving the accuracy of the energy efficiency estimation of the battery pack. In the embodiment of the invention, influence factors causing energy loss of the battery pack in the integration process are specifically introduced, the influence factors at least comprise one of series battery cell energy deviation, a battery pack SOC usable interval, battery cell SOC difference in the battery pack, sensor precision and battery pack internal resistance, the influence factors considering the energy loss are more comprehensive, and the first actual usable energy without loss is comprehensively determined from the theoretical energy of the battery pack. And then, considering energy loss caused by the difference between the working temperature environment of the battery cells in the battery pack and the working temperature environment of the single battery cells and energy loss caused by self-discharge of the battery pack storage, and further redetermining the residual energy of the battery pack from the first actual available energy to obtain a second actual available energy. And finally, calculating the ratio of the second actual available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack, and further improving the accuracy of estimating the energy efficiency of the battery pack.
Fig. 3 shows an electronic device according to an embodiment of the present invention, where the device includes a processor 901 and a memory 902, which may be connected via a bus or in another manner, and fig. 3 illustrates an example of a connection via a bus.
Processor 901 may be a Central Processing Unit (CPU). The Processor 901 may also be other general purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, or combinations thereof.
The memory 902, which is a non-transitory computer-readable storage medium, may be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as program instructions/modules corresponding to the methods in the above-described method embodiments. The processor 901 executes various functional applications and data processing of the processor by executing non-transitory software programs, instructions and modules stored in the memory 902, that is, implements the methods in the above-described method embodiments.
The memory 902 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application program required for at least one function; the storage data area may store data created by the processor 901, and the like. Further, the memory 902 may include high speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, the memory 902 may optionally include memory located remotely from the processor 901, which may be connected to the processor 901 via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
One or more modules are stored in the memory 902, which when executed by the processor 901 perform the methods in the above-described method embodiments.
The specific details of the electronic device may be understood by referring to the corresponding related descriptions and effects in the above method embodiments, and are not described herein again.
Those skilled in the art will understand that all or part of the processes in the methods of the embodiments described above may be implemented by instructing the relevant hardware through a computer program, and the implemented program may be stored in a computer-readable storage medium, and when executed, may include the processes of the embodiments of the methods described above. The storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a Flash Memory (Flash Memory), a Hard Disk (Hard Disk Drive, abbreviated as HDD) or a Solid State Drive (SSD), etc.; the storage medium may also comprise a combination of memories of the kind described above.
Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims (10)

1. A method of estimating energy efficiency of a battery pack, the method comprising:
calculating first actual available energy of the battery pack based on influence factors causing energy loss of the battery pack in an integration process, wherein the integration process is a process of integrating single battery cells into the battery pack, and the influence factors at least comprise one of series battery cell energy deviation, a battery pack SOC (state of charge) usable interval, battery cell SOC difference in the battery pack, sensor precision and battery pack internal resistance;
adjusting the first actual available energy based on energy loss caused by working temperature environment difference of the battery pack and energy loss caused by storage discharge to obtain second actual available energy of the battery pack, wherein the working temperature environment difference is the difference between the working temperature environment of the battery cell in the battery pack and the working temperature environment of the single battery cell;
and calculating the ratio of the second practical available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack.
2. The method of claim 1, wherein calculating the first actual available energy of the battery pack based on the influencing factors causing the energy loss of the battery pack in the integration process comprises:
calculating theoretical energy of the battery pack based on the battery cell integrated structure;
calculating the corresponding loss energy value of the battery pack or the proportionality coefficient of the residual energy of the battery pack after the energy is lost through the influence factors;
and determining the first actual available energy from the theoretical energy of the battery pack through the proportionality coefficient and the loss energy value.
3. The method of claim 2, wherein the calculating the theoretical energy of the battery pack based on the cell integration structure comprises:
acquiring the serial quantity and the parallel quantity of the battery cells in the battery pack according to the battery cell integrated structure;
and obtaining the theoretical energy of the battery pack by the product of the serial number, the parallel number, the nominal capacity of the single battery cell and the nominal voltage of the single battery cell.
4. The method of claim 3, wherein calculating a scaling factor for the remaining energy of the battery pack after the energy loss by the influencing factor comprises:
calculating a first ratio of minimum single cell energy to nominal single cell energy in the battery pack to obtain a first ratio coefficient for representing energy deviation of the series cells;
calculating a difference value between the use upper limit and the use lower limit of the SOC of the battery pack to obtain a second proportionality coefficient for representing the SOC usable interval of the battery pack;
calculating a second ratio of the cell energy difference to the minimum single cell energy, calculating a product of the second ratio and the square of the parallel quantity, and then negating the calculation result in a percentage interval to obtain a third proportionality coefficient for representing the cell SOC difference in the battery pack, wherein the cell energy difference comprises the energy difference between cells caused by the capacity grading equipment precision difference and the energy difference caused by the self-discharge difference between the cells when the integration process is executed;
acquiring sampling energy loss of a sensor error, calculating a third ratio of the sampling energy loss to the minimum single cell energy, and then negating the third ratio in a percentage interval to obtain a fourth proportionality coefficient for representing the accuracy of the sensor;
wherein the first scaling factor, the second scaling factor, the third scaling factor, and the fourth scaling factor all belong to the scaling factor.
5. The method of claim 4, wherein calculating the corresponding energy loss value of the battery pack from the influencing factors comprises:
and calculating the energy consumption of the electrical connection mechanism in the battery pack based on the product of the square of the nominal current of the battery pack and the internal resistance of the battery pack, and taking the energy consumption of the electrical connection mechanism in the battery pack as the loss energy value of the battery pack.
6. The method of claim 5, wherein said determining said first actual available energy from said theoretical energy of said battery pack by said scaling factor and said lost energy value comprises:
calculating the product of the theoretical energy of the battery pack and the first proportional coefficient, the second proportional coefficient, the third proportional coefficient and the fourth proportional coefficient to obtain the intermediate quantity of the residual energy;
and calculating the difference value between the intermediate quantity of the residual energy and the energy consumption of the electrical connection mechanism in the battery pack to obtain the first actual available energy.
7. The method of claim 3, further comprising:
calculating the ratio of the second actual available energy to the nominal voltage of the single battery cell and the serial number to obtain the actual capacity of the battery pack;
and calculating the ratio of the actual capacity of the battery pack to the nominal capacity of the single battery cells and the parallel connection quantity to obtain the capacity efficiency of the battery pack.
8. An apparatus for estimating energy efficiency of a battery pack, the apparatus comprising:
the first loss unit is used for calculating first actual available energy of the battery pack based on influence factors causing energy loss of the battery pack in an integration process, wherein the integration process is a process of integrating single battery cells into the battery pack, and the influence factors at least comprise one of series battery cell energy deviation, a battery pack SOC (state of charge) usable interval, battery cell SOC difference in the battery pack, sensor precision and battery pack internal resistance;
the second loss unit is used for adjusting the first actual available energy based on energy loss caused by the working temperature environment difference of the battery pack and energy loss caused by storage discharge to obtain second actual available energy of the battery pack, wherein the working temperature environment difference is the difference between the working temperature environment of the battery cell in the battery pack and the working temperature environment of the single battery cell;
and the energy efficiency unit is used for calculating the ratio of the second actual available energy to the theoretical energy of the battery pack to obtain the energy efficiency of the battery pack.
9. An electronic device, comprising:
a memory and a processor communicatively coupled to each other, the memory having stored therein computer instructions, the processor executing the computer instructions to perform the method of any of claims 1-7.
10. A computer-readable storage medium having stored thereon computer instructions for causing a computer to thereby perform the method of any one of claims 1-7.
CN202210761367.XA 2022-06-29 2022-06-29 Estimation method and device for energy efficiency of battery pack and electronic equipment Pending CN115128470A (en)

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