CN115754740A

CN115754740A - Method and device for determining battery cell residual capacity deviation of battery system

Info

Publication number: CN115754740A
Application number: CN202211545467.5A
Authority: CN
Inventors: 吴彦威; 李志�; 杨超
Original assignee: Zhejiang Zero Run Technology Co Ltd; Zhejiang Lingxiao Energy Technology Co Ltd
Current assignee: Zhejiang Zero Run Technology Co Ltd; Zhejiang Lingxiao Energy Technology Co Ltd
Priority date: 2022-12-05
Filing date: 2022-12-05
Publication date: 2023-03-07

Abstract

The application relates to a method and a device for determining a cell residual capacity deviation of a battery system, wherein the battery system comprises a plurality of cells, and the method comprises the following steps: acquiring discharge data sent by the battery system, wherein the discharge data comprises cell voltages at all moments and the residual capacity of the battery system; respectively determining a first cell voltage corresponding to the first reference cell at each moment and a second cell voltage corresponding to the second reference cell at each moment; determining a first time based on a first cell voltage variation degree of the first reference cell, and determining a second time based on a second cell voltage variation degree of the second reference cell; and determining the deviation of the battery cell residual capacity of the battery system according to the first battery system residual capacity corresponding to the first time and the second battery system residual capacity corresponding to the second time.

Description

Method and device for determining residual capacity deviation of battery cell of battery system

Technical Field

The application relates to the technical field of new energy batteries, in particular to a method and a device for determining residual capacity deviation of a battery core of a battery system.

Background

With the development of new energy technology, new energy vehicles are also more and more valued. The battery system of the new energy vehicle is formed by connecting hundreds of battery cells in series and in parallel. In the actual production process, the micro short circuit behavior of part of the battery cell may be caused by the technological reasons of pole piece burrs, diaphragm defects, metal dust mixing and the like. Along with the change of time, the capacity difference between the micro short circuit battery cell and the normal battery cell is larger and larger. An increase in the capacity difference may exacerbate the battery life degradation and even cause safety problems in extreme cases. Therefore, it is very important for the battery system to accurately calculate the maximum cell remaining capacity deviation.

In the prior art, the remaining capacity (SOC) Of a cell is generally calculated, and then the maximum SOC value and the minimum SOC value in all the cells are subtracted to determine the maximum cell SOC deviation. The current common single cell SOC estimation method comprises the following steps: open circuit voltage method, ampere-hour integration, etc. The open-circuit voltage method requires the battery to reach a stable state when calculating the SOC of the single battery cell, and this process requires a long time and causes great difficulty in test. The ampere-hour integration method needs to perform long-time standing on the battery when calculating the SOC of the single battery cell, cannot realize online estimation, and is easily influenced by factors such as self-discharge, battery aging, temperature and the like.

Therefore, there is a need in the related art for a method for determining deviation of remaining capacity of battery cell of a battery system simply and accurately without being affected by the external environment.

Disclosure of Invention

In view of the above, it is necessary to provide a method and an apparatus for determining a deviation of a remaining battery cell capacity of a battery system, which are not affected by the external environment and can determine the deviation of the remaining battery cell capacity of the battery system simply and accurately.

In a first aspect, an embodiment of the present application provides a method for determining a cell residual capacity deviation of a battery system, where the battery system includes a plurality of cells, and the method includes:

acquiring discharge data sent by the battery system, wherein the discharge data comprises cell voltages at all times and the residual capacity of the battery system;

respectively determining a first cell voltage corresponding to the first reference cell at each moment and a second cell voltage corresponding to the second reference cell at each moment;

determining a first time based on a first cell voltage variation degree of the first reference cell, and determining a second time based on a second cell voltage variation degree of the second reference cell;

and determining the deviation of the battery cell residual capacity of the battery system according to the first battery system residual capacity corresponding to the first time and the second battery system residual capacity corresponding to the second time.

The embodiment of the application provides a method for determining a battery cell residual capacity deviation of a battery system, which may determine a voltage of a first reference battery cell and a voltage of a second reference battery cell at different times according to battery cell voltages of a plurality of battery cells acquired by the battery system at different times, and then determine a first time according to a variation degree of the voltage of the first reference battery cell and determine a second time according to a variation degree of the voltage of the first reference battery cell. And finally, determining the battery cell residual capacity deviation of the battery system according to the first battery system capacity corresponding to the first moment and the second battery system capacity corresponding to the second moment. Compared with the method for determining the deviation of the residual capacity of the battery cell by calculating the maximum residual capacity of the battery cell and the minimum residual capacity of the battery cell through an ampere-hour integration method, an open-circuit voltage method and the like in the prior art, the deviation of the residual capacity of the battery cell can be determined simply and accurately. In addition, the residual capacity of each battery cell does not need to be determined, and not only can errors caused by inaccurate calculation of the residual capacity be avoided, so that the calculation accuracy of the residual capacity deviation of the battery cell is improved, but also the efficiency of determining the capacity deviation of the battery cell can be improved.

Optionally, in an embodiment of the application, the determining a first cell voltage corresponding to the first reference cell at each time and a second cell voltage corresponding to the second reference cell at each time respectively includes:

taking the cell voltage meeting a first preset condition at each moment as the first cell voltage at each moment; the meeting of the first preset condition comprises that the cell voltage corresponding to the target moment is greater than a first preset cell voltage threshold value matched with the target moment;

taking the cell voltage meeting a second preset condition at each moment as the first cell voltage at each moment; and the meeting of the second preset condition comprises that the cell voltage corresponding to the target moment is smaller than a second preset cell voltage threshold value matched with the target moment.

Optionally, in an embodiment of the present application, the determining a first time based on a first cell voltage variation degree of the first reference cell and determining a second time based on a second cell voltage variation degree of the second reference cell, includes:

determining a first discharge curve of the first reference cell based on each of the first cell voltages; determining a second discharge curve of the second reference cell based on each second cell voltage;

a first time is determined based on a first curve slope of the first discharge curve and the second time is determined according to a second curve slope of the second discharge curve.

Optionally, in an embodiment of the present application, the determining a first time based on a slope of the first discharge curve and determining a second time according to a slope of the second discharge curve includes:

determining a first moment in time when the first curve slope is greater than a first slope threshold; and determining a second time instant if the second curve slope is greater than a second slope threshold.

Optionally, in an embodiment of the application, the obtaining discharge data sent by the battery system, where the discharge data includes a cell voltage and a battery system capacity at each time includes:

acquiring a residual capacity interval of a preset battery system;

and determining discharge data which are sent by the battery system and are in a preset battery residual capacity interval, wherein the discharge data comprise the cell voltage at each moment and the battery system residual capacity.

Optionally, in an embodiment of the present application, the determining a first discharge curve of the first reference cell based on each of the first cell voltages; and determining a second discharge curve of the second reference cell based on each of the second cell voltages, including:

determining a second reference discharge curve for the first reference cell based on each of the first cell voltages; determining a second reference discharge curve of the second reference cell based on each second cell voltage;

and performing smoothing filtering processing on the first reference discharge curve and the second reference discharge curve respectively to determine a first discharge curve of the first reference cell and a second discharge curve of the second reference cell.

In a second aspect, an embodiment of the present application further provides a device for determining a cell remaining capacity deviation of a battery system, where the battery system includes a plurality of cells, and the device includes:

the discharging data acquisition module is used for acquiring discharging data sent by the battery system, and the discharging data comprises cell voltages at all moments and the residual capacity of the battery system;

the reference cell voltage determining module is used for respectively determining a first cell voltage corresponding to the first reference cell at each moment and a second cell voltage corresponding to the second reference cell at each moment;

a time determination module, configured to determine a first time based on a first cell voltage variation degree of the first reference cell, and determine a second time based on a second cell voltage variation degree of the second reference cell;

and the battery cell residual capacity deviation determining module is used for determining the battery cell residual capacity deviation of the battery system according to the first battery system residual capacity corresponding to the first time and the second battery system residual capacity corresponding to the second time.

In a third aspect, an embodiment of the present application further provides an electronic device, which includes a memory and a processor, where the memory stores a computer program, and the processor implements the steps of the methods in the foregoing embodiments when executing the computer program.

In a fourth aspect, the present application further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the method described in the foregoing embodiments.

In a fifth aspect, the present application further provides a computer program product, which includes computer readable code or a non-volatile computer readable storage medium carrying computer readable code, when the computer readable code runs in a processor of an electronic device, the processor in the electronic device executes the method described in the foregoing embodiments.

Drawings

Fig. 1 is a schematic view of an application scenario provided in an embodiment of the present application;

FIG. 2 is a schematic diagram of a voltage-capacity characteristic of a battery provided in accordance with an embodiment of the present application;

fig. 3 is a flowchart of a method for determining a cell remaining capacity deviation of a battery system according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a first discharge curve provided in accordance with an embodiment of the present application;

fig. 5 is a schematic diagram for determining a first time and a second time according to an embodiment of the present application;

FIG. 6 is a graph illustrating an original discharge curve according to an embodiment of the present application;

FIG. 7 is a schematic illustration of a discharge curve after screening provided by an embodiment of the present application;

FIG. 8 is a schematic diagram of curve smoothing filtering provided by an embodiment of the present application;

fig. 9 is a schematic block diagram of a device for determining a cell remaining capacity deviation of a battery system according to an embodiment of the present disclosure;

fig. 10 is a schematic block diagram of an electronic device according to an embodiment of the present disclosure;

FIG. 11 is a conceptual partial view of a computer program product provided by embodiments of the present application.

Detailed Description

Various exemplary embodiments, features and aspects of the present application will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present application. It will be understood by those skilled in the art that the present application may be practiced without some of these specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present application.

In the embodiments of the present application, "/" may indicate a relationship in which the objects associated before and after are "or", for example, a/B may indicate a or B; "and/or" may be used to describe that there are three relationships for the associated object, e.g., A and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. For convenience of describing the technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "first", "second", and the like may be used to distinguish technical features having the same or similar functions. The terms "first," "second," and the like do not necessarily denote any order or importance, nor do the terms "first," "second," and the like denote any order or importance. In the embodiments of the present application, the words "exemplary" or "such as" are used to indicate examples, illustrations or illustrations, and any embodiment or design described as "exemplary" or "e.g.," should not be construed as preferred or advantageous over other embodiments or designs. The use of the terms "exemplary" or "such as" are intended to present relevant concepts in a concrete fashion for ease of understanding.

In the embodiment of the present application, for a technical feature, the technical features in the technical feature are distinguished by "first", "second", "third", "a", "B", "C", and "D", etc., where the technical features described in "first", "second", "third", "a", "B", "C", and "D" are not in a sequential order or a size order. Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present application. It will be understood by those skilled in the art that the present application may be practiced without some of these specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present application.

In the production process of the battery cell, micro short circuit can occur inside the battery cell due to various manufacturing process problems, so that an abnormal battery cell is formed. The self-discharge rate of the abnormal electric core is far greater than that of the normal electric core, so that the residual capacity of the electric core between the abnormal electric core and the normal electric core is greatly different. If the self-discharge rate difference between the electric cores is large, the residual capacity difference between the abnormal electric core and the normal electric core is larger and larger along with the influence of time, the charge and discharge performance of the battery system is seriously influenced, and even safety accidents can occur under extreme conditions. Therefore, calculating the deviation of the residual capacity of the battery cell of the battery system has important significance for the safe and efficient operation of the battery system.

In the related art, the ampere-hour integration method is usually used to calculate the battery cell residual capacity of each battery cell, and then the battery cell residual capacity deviation is calculated according to the highest battery cell residual capacity and the lowest battery cell residual capacity. However, when the ampere-hour integration method is used for calculating the battery cell residual capacity of the battery cell, the calculation error is larger and larger along with the accumulation of time, so that the determined deviation of the battery cell residual capacity is inaccurate.

Based on technical requirements similar to the above, embodiments of the present application provide a method for determining a cell remaining capacity deviation of a battery system, which may determine, according to cell voltages of a plurality of cells collected by the battery system at different times, a voltage of a first reference cell and a voltage of a second reference cell at different times, and then determine, according to a degree of change of the voltage of the first reference cell, the first time and determine the second time according to the degree of change of the voltage of the first reference cell. And finally, determining the deviation of the battery cell residual capacity of the battery system according to the first battery system capacity corresponding to the first moment and the second battery system capacity corresponding to the second moment. Compared with the method for determining the deviation of the residual capacity of the battery core by calculating the maximum residual capacity of the battery core and the minimum residual capacity of the battery core through an ampere-hour integration method, an open-circuit voltage method and the like in the prior art, the deviation of the residual capacity of the battery core can be determined simply and accurately. In addition, the residual capacity of each battery cell does not need to be determined, and not only can errors caused by inaccurate calculation of the residual capacity be avoided, so that the calculation accuracy of the residual capacity deviation of the battery cell is improved, but also the efficiency of determining the capacity deviation of the battery cell can be improved.

The method for determining the cell residual capacity deviation of the battery system provided by the embodiment of the application can be applied to application scenarios including but not limited to the scenario shown in fig. 1. As shown in fig. 1, this scenario includes a battery system 101 and a capacity deviation determination device 103. The Battery System includes a Battery Management System (BMS), and at least one Battery (cell). The battery system 101 may be disposed in an electric vehicle to provide all or part of the power for the electric vehicle. The electric vehicle may be a vehicle which mainly uses a power battery or a super capacitor as an energy source and is wholly or partially driven by a motor, and may be, for example, an electric automobile, an electric motorcycle, an electric bicycle, an electric forklift, and the like. Certainly, in other application scenarios, such as a base station energy storage scenario and a data center power backup scenario, the battery system 101 may also be an energy storage system of a communication base station or a power backup system of a data center. The battery system 101 may be composed of a plurality of batteries (cells) connected in series and parallel, for example, the battery system 101 may be composed of 18 to 30 batteries connected in series and in parallel. It is understood that the plurality of batteries included in the battery system 101 generally belong to the same type of battery. The battery can be of various types, such as lithium iron phosphate batteries, lead acid batteries, lithium manganate batteries and the like. The battery management system can monitor and collect the state parameters (including but not limited to the voltage of a single battery, the temperature of a battery pole, the current of a battery loop, the terminal voltage of a battery pack, the insulation resistance of the battery system 101 and the like) of the battery in real time, and analyze and process the related state parameters. For example, the battery management system may be provided with a temperature sensor for detecting the pole temperatures of the plurality of batteries, and may be provided with a voltage sensor for detecting the cell voltages of the plurality of batteries, or the like. The battery system 101 may communicate with the capacity deviation determination device 103 through a network, and is configured to send the collected state parameters of the multiple batteries, such as discharge data, to the capacity deviation determination device 103, and the capacity deviation determination device 103 determines a cell remaining capacity deviation of the battery system 101.

It should be noted that the capacity deviation determining apparatus 103 may be an electronic device with data processing capability and data transceiving capability, and the electronic device may be a physical device or a physical device cluster, such as a server or a server cluster. Of course, the electronic device may also be a virtualized cloud device, such as at least one cloud computing device in a cloud computing cluster. In other embodiments of the present application, the capacity deviation determining device 103 may also be integrated into a Micro Controller Unit (MCU) or a Vehicle Control Unit (VCU) of the electric Vehicle, so that the electric Vehicle also has a function of determining the deviation of the remaining battery cell capacity.

The core idea on which the present application is based is explained below. In an actual application scenario, a voltage-capacity characteristic curve of a battery may have a section with a relatively slow voltage change, which may be referred to as a voltage plateau region. For example, there may be two voltage plateau regions or three voltage plateau regions. Taking the existence of two voltage plateau regions as an example, as shown in fig. 2, a region with a relatively fast voltage change exists between the two voltage plateau regions, and a point in the region with the fastest voltage change is called a voltage plateau inflection point. The inventors found that, for a battery system composed Of the same cells, the remaining capacities (SOCs) corresponding to the inflection points Of the voltage-capacity characteristic curves Of all the batteries in the system are the same. For example, as shown in table 1 below, when the cell a reaches the inflection point at time t1, the corresponding cell SOC is 60%, at this time, the cell SOC of the cell b is m%, and the battery system SOC is x%; the battery cell b reaches the inflection point at the moment t2, the corresponding battery cell SOC is 60%, the battery cell SOC of the battery cell a is 60% -n%, and the battery system SOC is y%.

TABLE 1 Battery cell SOC and Battery System SOC at different times

Time of day	Cell SOC of a cell	b cell SOC of cell	Battery system SOC
				t1
	60％	m％	x％
				t2
	60％-n％	60％	y％

On the basis of an ampere-hour integration method, the change of the cell SOC of the a battery cell is the same as the change of the battery system SOC within the same time interval, namely n = y-x. On this basis, the SOC deviation between the cell SOC of the a cell and the cell SOC of the b cell may be 60% to m%, or 60% to n% to 60% = -n% = (x-y)%. As can be seen from this, the remaining capacity deviation (SOC deviation) between the two battery cells can be determined by the system remaining capacity (system SOC) deviation corresponding to two times when the voltage-capacity characteristic curves of the two battery cells reach the inflection point. Therefore, the residual capacity deviation between the battery cores can be determined without determining the residual capacity of each battery core, so that the calculation steps are saved, and the efficiency and the accuracy for determining the residual capacity deviation of the battery cores are improved.

The following describes a method for determining a cell remaining capacity deviation of a battery system according to the present application in detail with reference to the accompanying drawings. Although the present application provides method steps as shown in the following examples or figures, more or fewer steps may be included in the method based on conventional or non-inventive efforts. In the case of steps where no necessary causal relationship exists logically, the order of execution of the steps is not limited to that provided by the embodiments of the present application. The method can be executed in sequence or in parallel according to the method shown in the embodiment or the figure when the method is executed in an actual object processing process or a device (for example, a parallel processor or a multi-thread processing environment).

The following describes a method for determining a cell remaining capacity deviation of a battery system in detail with reference to fig. 3, where as shown in fig. 3, the method may include:

s301: and acquiring discharge data sent by the battery system, wherein the discharge data comprises the cell voltage and the residual capacity of the battery system at each moment.

In this embodiment, the battery management system and the like may be used to collect voltages of a plurality of batteries (electric cores) in the battery system 101. The voltage sensors that may be utilized in the battery management system may include, for example, resistive voltage dividers, capacitive voltage dividers, electromagnetic voltage transformers, capacitive voltage transformers, hall voltage sensors, and the like. It can be understood that the battery management system does not need to additionally add a sensor for collecting the cell voltage, and the amount of data to be stored and the calculation amount of the data is small. Of course, the voltages of the individual battery cells may also be detected by other voltage detectors, which is not limited herein. The voltage values of the same single battery cell are different at different moments, and the voltage sensor can continuously acquire the voltage values of a plurality of battery cells within a preset sampling time interval. The preset sampling time interval may be set to 1s, 2s, 3s, etc. For example, in an example, the battery system 101 includes 3 battery cells, and the battery management system may acquire, at a sampling time k, a voltage of the battery cell 1 as a, a voltage of the battery cell 2 as B, and a voltage of the battery cell 3 as C. The sampling time may be each data acquisition time point at which the battery management system acquires the cell voltages according to the preset sampling time interval. In an embodiment Of the present application, the battery management system may further collect a remaining capacity (SOC) Of the battery system at different sampling times. The battery system SOC, i.e., the state of charge, may be used to reflect the remaining capacity of the battery system 101. The battery system SOC may be a ratio of the remaining capacity to the total capacity of the battery system, and may be, for example, 50%, 60%, 70%, or the like. For example, in one example, the battery management system may collect the battery system SOC of 50% at the sampling time t1 and 51% at the sampling time t2. In an embodiment of the present application, the discharge data is data collected when the battery system is in a discharge state. Of course, in other embodiments of the present application, the battery management system may also collect the current of multiple batteries.

S303: and respectively determining a first cell voltage corresponding to the first reference cell at each moment and a second cell voltage corresponding to the second reference cell at each moment.

In the embodiment of the application, in order to save the calculation steps and improve the calculation efficiency, a representative voltage value may be selected from the voltage values of the battery cells as the voltage value of the reference battery cell, so that the cell voltages of the reference battery cell at different times may be determined. It may be understood that the reference cells are virtual cells, and since it is subsequently necessary to determine a capacity deviation between the cells, the reference cells may be two, for example, the reference cells may be a first reference cell and a second reference cell. In an embodiment of the present application, the larger the cell capacity deviation is, the larger the influence on the charging and discharging performance of the battery system 101 is. Therefore, the maximum cell capacity deviation may be determined to determine the degree of influence on the charge and discharge performance of the battery system 101, and the maximum cell capacity deviation is generally determined by the maximum cell residual capacity and the minimum cell residual capacity. On this basis, in an embodiment of the present application, the determining a first cell voltage corresponding to the first reference cell at each time and a second cell voltage corresponding to the second reference cell at each time respectively includes:

s401: taking the cell voltage meeting a first preset condition at each moment as the first cell voltage at each moment; the meeting of the first preset condition comprises that the cell voltage corresponding to the target moment is greater than a first preset cell voltage threshold value matched with the target moment;

s403: taking the cell voltage meeting a second preset condition at each moment as the first cell voltage at each moment; and the meeting of the second preset condition comprises that the cell voltage corresponding to the target moment is smaller than a second preset cell voltage threshold value matched with the target moment.

In the embodiment of the application, the battery management system can acquire voltage data of different battery cores at different sampling moments. For example, as shown in table 2 below, the battery system 101 includes an a cell, a b cell, a c cell, and a d cell.

TABLE 2 cell voltmeter for different cells at different times

Time of day	Voltage value of a electric core	Voltage value of b electric core	Voltage value of c cell	Voltage value of d cell
					t1	A1	B1	C1	D1
t2	A2	B2	C2	D2
					t3	A3	B3	C3	D3

In an embodiment of the application, the voltage value of the first reference cell at a certain time may be determined according to a maximum voltage value among four cell voltage values at the certain time, or may be determined according to a voltage value, which is greater than a first preset voltage threshold, among the four cell voltage values. Of course, the determination may also be performed according to an average value of a plurality of voltage values greater than the first preset voltage threshold among the four cell voltage values, and the application is not specifically limited herein. For example, in one example, the voltage value of the first reference cell may be determined as A1 at time t1, the voltage value of the first reference cell may be determined as B2 at time t2, and the voltage value of the first reference cell may be determined as A3 at time t 3. It can be understood that, at different times, a user may set different first preset cell voltage thresholds according to actual application requirements and acquisition conditions. For example, at the time t1, the preset cell voltage threshold may be a maximum value of the four cell voltage values, or may be a median value of the four cell voltage values. Similarly, the voltage value of the second reference cell at a certain time may be determined according to the minimum voltage value of the four cell voltage values at the certain time, or may also be determined according to a voltage value smaller than a second preset voltage threshold value of the four cell voltage values. Of course, the determination may also be performed according to an average value of a plurality of voltage values smaller than the second preset voltage threshold among the four cell voltage values, and the application is not specifically limited herein. The method for determining the second preset cell voltage threshold may refer to the method for determining the first preset cell voltage threshold, which is not described herein again. In this way, the first reference cell may actually be used to represent a cell having a relatively high cell voltage at any time, and the second reference cell may actually be used to represent a cell having a relatively low cell voltage at any time, so that when a residual capacity deviation of the cell is subsequently determined, a maximum residual capacity deviation of the cell may be determined, so as to more accurately represent an abnormal condition of the battery system. In addition, when the cell voltage variation degree is judged, the first time and the second time can be determined more accurately, so that the abnormal degree of the battery system can be described more accurately when the cell capacity deviation value is determined subsequently. And the voltage change degree of all the battery cells does not need to be calculated, so that the time can be saved, the processing burden of processing can be reduced, and the calculation efficiency can be improved.

In the embodiment of the present application, the plurality of battery cells may be battery cells of the same type or the same specification, or battery cells of different types or different specifications. When the plurality of battery cells included in the battery system 101 are all of the same type of battery cell, the method described in the foregoing embodiment may be used to determine a first cell voltage corresponding to a first reference battery cell at each time and a second cell voltage corresponding to a second reference battery cell at each time. In other embodiments of the present application, when a plurality of battery cells included in the battery system 101 are different types of battery cells, the cell voltages of the plurality of battery cells may be divided into different sets according to the types of the battery cells, and then a first cell voltage corresponding to a first reference battery cell in each set at each time may be determined, and a second cell voltage corresponding to a second reference battery cell at each time may be determined. It can be understood that, in the subsequent calculation, it is necessary to determine a voltage-capacity characteristic curve according to the type of the battery cell, determine the time corresponding to the reference battery cell in different sets, and finally calculate the residual capacity deviation of the battery cell corresponding to each set respectively.

S305: a first time is determined based on a first cell voltage variation degree of the first reference cell, and a second time is determined based on a second cell voltage variation degree of the second reference cell.

In this embodiment of the application, the voltage variation degree may be a degree that the voltage of the reference cell varies with the variation of the sampling time, where the degree may be a magnitude of a variation in the cell voltage with time. In order to enable a user to observe the variation degree of the reference cell more clearly and determine the first time and the second time more accurately, a discharge curve may be drawn based on the sampling time and the cell voltage, and then the first time and the second time may be determined according to a slope of the discharge curve. Specifically, in an embodiment of the present application, the determining a first time based on a first degree of cell voltage change of the first reference cell and determining a second time based on a second degree of cell voltage change of the second reference cell includes:

s501: determining a first discharge curve of the first reference cell based on each of the first cell voltages; determining a second discharge curve of the second reference cell based on each second cell voltage;

s503: a first time is determined based on a first curve slope of the first discharge curve and the second time is determined according to a second curve slope of the second discharge curve.

In this embodiment, the sampling time may be used as an abscissa, and the first cell voltage value corresponding to the sampling time may be used as an ordinate, so as to determine the first discharge curve. For example, as shown in fig. 4, the first discharge curve V (t) may be plotted with the sampling time t as an abscissa and the first cell voltage value V as an ordinate. In an embodiment of the present application, after the first discharge curve is determined, a degree of change of the first cell voltage may be determined according to a slope of the first discharge curve. On this basis, the degree of change may be Δ V/Δ t. In one embodiment of the present application, the slope of the discharge curve may be determined by deriving the discharge curve based on the sampling time t. For example, in one example, the slope of the first curve may be determined based on d (V (t))/dt. Similarly, the determination of the slope of the second discharge curve may also be determined by referring to the slope method of the first discharge curve, which is not described herein again. In an embodiment of the present application, after determining the first slope, a time corresponding to a maximum value of the first slope may be determined as a first time, for example, a time corresponding to a point at which a curve corresponding to the first slope reaches an inflection point is a first time. Of course, in other embodiments of the present application, the determining a first time point as a time point when the slope of the first curve is greater than a set value, specifically, the determining a first time point based on the slope of the first discharge curve and determining the second time point according to the slope of the second discharge curve may include:

s603: determining a first moment when the slope of the first curve is greater than a first preset slope threshold; and determining a second moment in time when the slope of the second curve is greater than a second preset slope threshold.

In this embodiment of the application, the first preset slope threshold may be set by a user according to an actual cell specification and a cell discharge characteristic, and may be set to 0.15, 0.2, 0.25, and so on, for example. Of course, the first preset slope threshold may also be calculated by the user according to a theoretical basis, and the method for determining the first preset slope threshold is not limited in this application. After the first preset slope threshold is determined, a first time may be determined according to a comparison result of the first curve slope and the first preset slope threshold. For example, in one example, as shown in fig. 5, the first curve slope a1 is greater than a first preset slope threshold a, so that the first time t1 can be determined; the first curve slope b1 is greater than a first preset slope threshold b, so that the first time t2 can be determined. Through the embodiment, the first time and the second time can be directly and accurately determined according to the slope of the discharge curve, so that a more accurate deviation of the residual capacity of the battery cell can be determined.

It can be understood that the time when the slope of the first curve is the maximum or the time when the slope of the first curve is greater than the first preset slope threshold is the time when the voltage-capacity characteristic curve of the first reference cell reaches the inflection point. Similarly, the time when the slope of the second curve is the maximum or the time when the slope of the second curve is greater than the second preset slope threshold is the time when the voltage-capacity characteristic curve of the second reference cell reaches the inflection point, so that the residual capacity difference of the battery system in the time difference is the cell residual capacity deviation of the first reference cell and the second reference cell.

In practical applications, in the discharging process of the battery system 101, the fluctuation range of the cell current is relatively large, which results in a relatively large fluctuation range of the collected cell voltage. As shown in fig. 6, fig. 6 shows a discharge curve determined from raw discharge data. It can be seen that the upper and lower fluctuation ranges of the discharge curve are large, and the change degree of the cell voltage cannot be accurately determined, i.e. the more accurate discharge curve cannot be determined, so that the accuracy of subsequently determining the residual capacity difference of the cell is influenced. Based on this, in an embodiment of the application, the acquired cell voltage may be screened according to a comparison result between the acquired cell current and a current of a preset current threshold, so as to determine a more accurate discharge curve. The preset current threshold may be set by a user according to actual screening requirements, and may be set to 2A, 2.5A, 3A, and so on. In an embodiment of the present application, the cell voltages may be screened by using a window function method. The window function method may include rectangular windows, hanning windows, flat-top windows, exponential windows, and the like. For example, in an example, in a case that the width of the rectangular window is 1, data that the cell current in the window is greater than a preset current threshold may be filtered out, as shown in fig. 7, where fig. 7 shows a discharge curve determined according to the filtered discharge data in a case that the window is 1. In another example, in a case that the width of the rectangular window is 2, data that the cell current acquired at two consecutive sampling instants is smaller than a preset current threshold may be retained. It can be understood that, the larger the window size is, the less the data is satisfied, and the smaller the data amount is, so that the cell voltage variation degree may not be reflected. Similarly, the smaller the window size is, the more data is satisfied, but the larger the noise is, the more accurate cell voltage change degree may not be obtained. Therefore, in an embodiment of the present application, the size of the window needs to be set to a reasonable value, so that a more accurate cell voltage variation degree can be determined. For example, the window may be set to a size of 5.

Through the embodiment, the collected cell voltages can be screened, so that the characteristic of the cell voltage variation trend can be retained to the greatest extent, and the influence of large current on the cell voltages can be reduced.

In practical applications, when the battery management system collects the cell voltages of the plurality of cells in the battery system 101, the collection accuracy may be affected by external factors, so that noise may exist in the first cell voltage or the second cell voltage. Based on this, in an embodiment of the present application, in order to improve the accuracy of determining the first cell voltage and the second cell voltage, a smoothing filter process may be performed on the first discharge curve and the second discharge curve. Specifically, the determining of the first discharge curve of the first reference cell is performed based on each of the first cell voltages; and determining a second discharge curve of the second reference cell based on each of the second cell voltages, including:

s701: determining a second reference discharge curve for the first reference cell based on each of the first cell voltages; determining a second reference discharge curve of the second reference cell based on each second cell voltage;

s703: and performing smoothing filtering processing on the first reference discharge curve and the second reference discharge curve respectively to determine a first discharge curve of the first reference cell and a second discharge curve of the second reference cell.

In the embodiment of the application, the first reference discharge curve may be directly determined according to the first cell voltage at each time. The first reference discharge curve may then be smoothly filtered to determine a final first discharge curve. In an embodiment of the present application, the first reference discharge curve may be subjected to a smoothing filtering process by using a polynomial smoothing algorithm, a neighborhood smoothing filtering algorithm, a median filtering algorithm, a kalman filtering algorithm, a gaussian filtering algorithm, or the like. For example, in one example, as shown in fig. 8, the first and second reference discharge curves are smoothly filtered to determine the first and second discharge curves. Specifically, the method can be implemented by python built-in function script. Where x is the data to be filtered. Polyorder is the polynomial order used to fit the samples. window _ length is the length of the filter window. For example, the reorder may be set to 2, and the window _ length may be set to 211. Similarly, the processing of the second discharge curve may also be determined by referring to the processing method of the second discharge curve, which is not described herein again.

Through the embodiment, the discharging curve can be subjected to smooth filtering to remove noise points in the discharging curve, namely, misjudgment caused by abnormal data points in special conditions can be filtered out, and the determined discharging curve is more accurate.

Since the voltage-capacity characteristic curve of the battery may have a plurality of sections in which the voltage changes slowly, that is, a plurality of inflection points may exist. The voltage is distinguished by high and low, the higher voltage is called high voltage plateau inflection point, and the lower voltage is called low voltage plateau inflection point. Therefore, there may be inflection points at different positions throughout the cell SOC interval. In order to distinguish inflection points to determine a first time and a second time that are more accurate, in an embodiment of the present application, the obtaining discharge data sent by the battery system, where the discharge data includes a cell voltage and a battery system capacity at each time includes:

s801: acquiring a residual capacity interval of a preset battery system;

s803: and determining discharge data which are sent by the battery system and are in a preset battery residual capacity interval, wherein the discharge data comprise the cell voltage and the residual capacity of the battery system at each moment.

In this embodiment of the application, the preset battery system remaining capacity interval may be set by a user according to characteristics of the battery system 101 and a cell performance of the battery cell, for example, the preset battery system remaining capacity interval may be set to 90% to 100%, or set to 0% to 50%. Of course, the preset battery system residual capacity interval may also be set to 50% -90%, and the specific preset battery system residual capacity interval setting may be determined according to specific calculation requirements. The only inflection point can be determined in the determined system SOC interval by setting the preset battery system residual capacity interval in advance, so that the calculation accuracy is prevented from being influenced by confusion.

S307: and determining the deviation of the battery cell residual capacity of the battery system according to the first battery system residual capacity corresponding to the first time and the second battery system residual capacity corresponding to the second time.

In this embodiment, after determining a first time and a second time, a first remaining battery system capacity corresponding to the first time and a second remaining battery system capacity corresponding to the second time may be determined from the obtained discharge data. For example, it may be determined that the first time corresponds to a first battery system residual capacity of 65%, and the second time corresponds to a second battery system residual capacity of 60%. After determining the first battery system remaining capacity and the second battery system remaining capacity, a cell remaining capacity deviation of the battery system may be determined according to a difference between the first battery system remaining capacity and the second battery system remaining capacity. For example, the cell remaining capacity deviation may be determined to be 5%.

The method for determining the battery cell residual capacity deviation of the battery system, provided by each embodiment of the present application, may determine, according to the cell voltages of the multiple battery cells acquired by the battery system at different times, the voltage of the first reference battery cell and the voltage of the second reference battery cell at different times, and then may determine, according to the degree of change of the voltage of the first reference battery cell, the first time and determine, according to the degree of change of the voltage of the first reference battery cell, the second time. And finally, determining the deviation of the battery cell residual capacity of the battery system according to the first battery system residual capacity corresponding to the first moment and the second battery residual system capacity corresponding to the second moment. Compared with the method for determining the deviation of the residual capacity of the battery cell by calculating the maximum residual capacity of the battery cell and the minimum residual capacity of the battery cell through an ampere-hour integration method, an open-circuit voltage method and the like in the prior art, the deviation of the residual capacity of the battery cell can be determined simply and accurately. In addition, the residual capacity of each battery cell does not need to be determined, so that errors caused by inaccurate calculation of the residual capacity can be avoided, and the calculation accuracy of the residual capacity deviation of the battery cell is improved; and calculation steps can be saved, and the efficiency of determining the capacity deviation of the battery core is improved.

It should be understood that, although the steps in the flowcharts related to the embodiments as described above are sequentially displayed as indicated by arrows, the steps are not necessarily performed sequentially as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a part of the steps in the flowcharts related to the embodiments described above may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, and the execution order of the steps or stages is not necessarily sequential, but may be performed alternately or alternately with other steps or at least a part of the steps or stages in other steps.

In another aspect, a device for determining a cell remaining capacity deviation of a battery system is further provided, as shown in fig. 9, where the battery system includes a plurality of battery cells, and the device 700 may include:

a discharge data obtaining module 701, configured to obtain discharge data sent by the battery system, where the discharge data includes a cell voltage at each time and a remaining capacity of the battery system;

a reference cell voltage determining module 703, configured to determine a first cell voltage corresponding to the first reference cell at each time and a second cell voltage corresponding to the second reference cell at each time, respectively;

a time determination module 705, configured to determine a first time based on a first cell voltage variation degree of the first reference cell, and determine a second time based on a second cell voltage variation degree of the second reference cell;

a battery cell remaining capacity deviation determining module 707, configured to determine a battery cell remaining capacity deviation of the battery system according to a first battery system remaining capacity corresponding to the first time and a second battery system remaining capacity corresponding to the second time.

Optionally, in an embodiment of the present application, the device 700 for determining a cell remaining capacity deviation of the battery system is configured to:

determining a first time when the first curve slope is greater than a first slope threshold; and determining a second time instant if the second curve slope is greater than a second slope threshold.

Optionally, in an embodiment of the present application, the apparatus 700 for determining a cell remaining capacity deviation of the battery system is configured to:

acquiring a residual capacity interval of a preset battery system;

It should be noted that the above-described embodiments are merely illustrative, wherein the modules described as separate parts may or may not be physically separate, and the parts displayed as modules may or may not be physical modules, may be located in one place, or may be distributed on a plurality of network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. In addition, in the drawings of the embodiments of the apparatus provided in the present application, the connection relationship between the modules indicates that there is a communication connection therebetween, and may be implemented as one or more communication buses or signal lines.

As shown in fig. 10, an embodiment of the present application further provides an electronic device 800, where the electronic device 800 includes: a processor and a memory for storing processor-executable instructions; wherein the processor is configured to implement the above method when executing the instructions. The electronic device 800 includes a memory 801, a processor 803, a bus 805, and a communication interface 807. The memory 801, processor 803 and communication interface 807 communicate over a bus 805. The bus 805 may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 10, but that does not indicate only one bus or one type of bus. The communication interface 807 is used for communication with the outside. The processor 803 may be a Central Processing Unit (CPU). The memory 801 may include a volatile memory (volatile memory), such as a Random Access Memory (RAM). The memory 801 may also include a non-volatile memory (non-volatile memory), such as a read-only memory (ROM), a flash memory, an HDD, or an SSD. The memory 801 stores executable code that is executed by the processor 803 to perform the methods described in the various embodiments above.

Embodiments of the present application provide a non-transitory computer readable storage medium having stored thereon computer program instructions which, when executed by a processor, implement the above-described method.

Embodiments of the present application provide a computer program product comprising computer readable code, or a non-transitory computer readable storage medium carrying computer readable code, which when run in a processor of an electronic device, the processor in the electronic device performs the above method.

In some embodiments, the disclosed methods may be implemented as computer program instructions encoded on a computer-readable storage medium in a machine-readable format or encoded on other non-transitory media or articles of manufacture. Fig. 11 schematically illustrates a conceptual partial view of an example computer program product comprising a computer program for executing a computer process on a computing device, arranged in accordance with at least some embodiments presented herein. In one embodiment, the example computer program product 900 is provided using a signal bearing medium 901. The signal bearing medium 901 may include one or more program instructions 902 that, when executed by one or more processors, may provide the functions or portions of the functions described above with respect to fig. 3. Further, program instructions 902 in FIG. 11 also describe example instructions.

In some examples, signal bearing medium 901 may comprise a computer readable medium 903 such as, but not limited to, a hard disk drive, a Compact Disc (CD), a Digital Video Disc (DVD), a digital tape, a Memory, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like. In some implementations, the signal bearing medium 901 may comprise a computer recordable medium 904 such as, but not limited to, a memory, a read/write (R/W) CD, a R/W DVD, and the like. In some implementations, the signal bearing medium 901 may include a communication medium 905, such as, but not limited to, a digital and/or analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link, etc.). Thus, for example, the signal bearing medium 901 may be communicated by a wireless form of communication medium 905 (e.g., a wireless communication medium conforming to the IEEE 902.11 standard or other transmission protocol). The one or more program instructions 902 may be, for example, computer-executable instructions or logic-implementing instructions. In some examples, a computing device, such as the electronic device described with respect to fig. 10, may be configured to provide various operations, functions, or actions in response to program instructions 902 conveyed to the computing device by one or more of the computer-readable medium 903, the computer-recordable medium 904, and/or the communication medium 905. It should be understood that the arrangements described herein are for illustrative purposes only. Thus, those skilled in the art will appreciate that other arrangements and other elements (e.g., machines, interfaces, functions, orders, and groupings of functions, etc.) can be used instead, and that some elements may be omitted altogether depending upon the desired results. In addition, many of the described elements are functional entities that may be implemented as discrete or distributed components or in conjunction with other components, in any suitable combination and location. The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, systems, and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

It is also noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by hardware (e.g., a Circuit or an ASIC) for performing the corresponding function or action, or by combinations of hardware and software, such as firmware.

While the invention has been described in connection with various embodiments, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a review of the drawings, the disclosure, and the appended claims. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, and these are all within the scope of protection of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A method for determining a cell residual capacity deviation of a battery system, the battery system comprising a plurality of cells, the method comprising:

and determining the deviation of the battery cell residual capacity of the battery system according to the first battery system residual capacity corresponding to the first moment and the second battery system residual capacity corresponding to the second moment.

2. The method of claim 1, wherein the separately determining a first cell voltage for the first reference cell at each time and a second cell voltage for the second reference cell at each time comprises:

3. The method of claim 1, wherein determining the first time based on a first degree of cell voltage change of the first reference cell and determining the second time based on a second degree of cell voltage change of the second reference cell comprises:

4. The method of claim 3, wherein determining the first time based on the slope of the first discharge curve and the second time based on the slope of the second discharge curve comprises:

5. The method according to claim 1, wherein the obtaining discharge data sent by the battery system, the discharge data including cell voltages at various times and a battery system capacity, comprises:

acquiring a residual capacity interval of a preset battery system;

6. The method of claim 3, wherein the determining a first discharge curve for the first reference cell is based on each of the first cell voltages; and determining a second discharge curve of the second reference cell based on each of the second cell voltages, including:

7. A cell remaining capacity deviation determination apparatus of a battery system including a plurality of cells, the apparatus comprising:

a time determination module, configured to determine a first time based on a first cell voltage change degree of the first reference cell, and determine a second time based on a second cell voltage change degree of the second reference cell;

8. An electronic device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor realizes the steps of the method of any of claims 1 to 6 when executing the computer program.

9. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 6.

10. A computer program product comprising computer readable code or a non-transitory computer readable storage medium carrying computer readable code which, when run in a processor of an electronic device, the processor in the electronic device performs the method of any of claims 1-6 above.