CN117092527A - Method and system for determining self-discharge of battery - Google Patents

Abstract

The present invention relates to a method for determining self-discharge of a battery and a system for determining self-discharge of a battery. According to one aspect of the invention, a method for determining self-discharge of a battery is proposed, comprising the steps of: determining a capacity increment of the plurality of cells from the charging current and the cell voltage of the plurality of cells in response to the battery being in a slow charge state; determining a valley phase of the plurality of cells at a valley of a capacity increment corresponding to each of the plurality of cells; determining a valley phase difference of the plurality of cells based on the valley phases of the plurality of cells; and judging that the battery including the battery cells is self-discharged in response to the valley phase difference of one or more battery cells among the valley phase differences of the plurality of battery cells meeting a preset condition.

Description

Method and system for determining self-discharge of battery

Technical Field

The present invention relates to the field of batteries, and more particularly to a method for determining self-discharge of a battery and a system for determining self-discharge of a battery.

Background

The lithium ion battery is an energy storage element widely applied in recent years, and is widely applied in the fields of consumer electronics, electric drive, energy storage power stations and the like due to the characteristics of high specific energy, high power density, high efficiency, environmental protection and the like.

The defect in the production and manufacturing process may cause micro-short circuit inside the lithium ion battery, and the micro-short circuit inside the battery may cause self-discharge of the battery, which is manifested by voltage drop, current increase, temperature increase and the like, thereby possibly causing premature failure and potential safety hazard of the battery.

Currently, self-discharge of a lithium ion battery is generally determined based on consistency indexes such as voltage and internal resistance of the lithium ion battery. However, due to inconsistent delivery capacity and state of charge of the lithium ion battery, the accuracy of judging the self-discharge of the lithium ion battery by using consistency indexes such as voltage, internal resistance and the like is low. Particularly, the voltage curve of the lithium iron phosphate battery is flat, so that the accuracy of judging the self-discharge of the lithium iron phosphate battery by using consistency indexes such as voltage, internal resistance and the like is further lower, false alarm and missing report are easy, and battery safety accidents are further possibly caused.

Disclosure of Invention

To solve or at least alleviate one or more of the above problems, the following solutions are provided.

According to a first aspect of the present invention there is provided a method for determining self-discharge of a battery, the method comprising the steps of: determining a capacity increment of the plurality of cells from the charging current and the cell voltage of the plurality of cells in response to the battery being in a slow charge state; determining a valley phase of the plurality of cells at a valley of a capacity increment corresponding to each of the plurality of cells; determining a valley phase difference of the plurality of cells based on the valley phases of the plurality of cells; and judging that the battery including the battery cells is self-discharged in response to the valley phase difference of one or more battery cells among the valley phase differences of the plurality of battery cells meeting a preset condition.

A method for determining self-discharge of a battery according to an embodiment of the present invention, wherein the slow charge state is determined based on a charge current value.

The method for determining battery self-discharge according to an embodiment of the present invention or any of the above embodiments, wherein determining the capacity increment of the plurality of cells from the charge current and the cell voltage of the plurality of cells comprises: collecting charging currents and cell voltages of a plurality of cells in real time in a battery charging process; performing low-pass filtering on the acquired cell voltages of the multiple cells; and determining a capacity increment of the plurality of cells based on the collected charging current of the plurality of cells and the low-pass filtered cell voltage.

The method for determining battery self-discharge according to an embodiment of the present invention or any of the above embodiments, wherein determining valley phases of the plurality of cells at the valleys of the capacity increment corresponding to each of the plurality of cells comprises: determining a plot of the capacity increment of each cell relative to the charge of the cell; determining a local minimum on a curve of the determined capacity increment of each cell relative to the charge amount of the cell as a valley of the capacity increment of each cell; and selecting the charge quantity of the battery cells at the valley value of the capacity increment of each battery cell to generate valley value phases of a plurality of battery cells.

The method for determining battery self-discharge according to an embodiment of the present invention or any of the above embodiments, wherein determining the valley phase differences of the plurality of cells based on the valley phases of the plurality of cells comprises: determining a valley phase minimum value of the valley phases of the plurality of battery cells; and subtracting the minimum value of the valley phases of the plurality of battery cells respectively from the valley phases of the plurality of battery cells to determine the valley phase difference of the plurality of battery cells.

The method for determining self-discharge of a battery according to an embodiment of the present invention or any of the above embodiments, wherein the preset conditions include one or more of the following: the valley value phase difference of the battery cell is larger than a first threshold value for a preset number of times, wherein the first threshold value is the nominal capacity of the battery cell in a first proportion; the valley value phase difference of the battery cell is larger than a second threshold value, and the second threshold value is the nominal capacity of the battery cell in a second proportion; and the valley phase difference of the battery core is larger than a third threshold value, the expansion rate of the valley phase difference of the battery core is larger than a fourth threshold value, the third threshold value is the nominal capacity of the battery core in a third proportion, and the fourth threshold value is the nominal capacity of the battery core in a fourth proportion divided by a preset charging time interval.

According to a second aspect of the present invention there is provided a system for determining self-discharge of a battery, the system comprising: a capacity increment determination module configured to determine a capacity increment of the plurality of battery cells from the charging current and the battery cell voltage of the plurality of battery cells in response to the battery being in a slow charge state; a valley phase determination module configured to determine valley phases of a plurality of cells at a valley of a capacity delta corresponding to each of the plurality of cells; a valley phase difference determination module configured to determine a valley phase difference of the plurality of cells based on the valley phases of the plurality of cells; and a judging module configured to judge that self-discharge of a battery including the battery cells occurs in response to a valley phase difference of one or more battery cells among the plurality of battery cells satisfying a preset condition.

A system for determining self-discharge of a battery according to an embodiment of the present invention, wherein the slow charge state is determined based on a charge current value.

The system for determining self-discharge of a battery according to an embodiment of the present invention or any of the above embodiments, wherein the capacity increment determination module is further configured to: collecting charging currents and cell voltages of a plurality of cells in real time in a battery charging process; performing low-pass filtering on the acquired cell voltages of the multiple cells; and determining a capacity increment of the plurality of cells based on the collected charging current of the plurality of cells and the low-pass filtered cell voltage.

The system for determining self-discharge of a battery according to an embodiment of the present invention or any of the above embodiments, wherein the valley phase determination module is further configured to: determining a plot of the capacity increment of each cell relative to the charge of the cell; determining a local minimum on a curve of the determined capacity increment of each cell relative to the charge amount of the cell as a valley of the capacity increment of each cell; and selecting the charge quantity of the battery cells at the valley value of the capacity increment of each battery cell to generate valley value phases of a plurality of battery cells.

The system for determining battery self-discharge according to an embodiment of the present invention or any of the above embodiments, wherein the valley phase difference determining module is further configured to: determining a valley phase minimum value of the valley phases of the plurality of battery cells; and subtracting the minimum value of the valley phases of the plurality of battery cells respectively from the valley phases of the plurality of battery cells to determine the valley phase difference of the plurality of battery cells.

The system for determining self-discharge of a battery according to an embodiment of the present invention or any of the above embodiments, wherein the preset conditions include one or more of the following: the valley value phase difference of the battery cell is larger than a first threshold value for a preset number of times, wherein the first threshold value is the nominal capacity of the battery cell in a first proportion; the valley value phase difference of the battery cell is larger than a second threshold value, and the second threshold value is the nominal capacity of the battery cell in a second proportion; and the valley phase difference of the battery core is larger than a third threshold value, the expansion rate of the valley phase difference of the battery core is larger than a fourth threshold value, the third threshold value is the nominal capacity of the battery core in a third proportion, and the fourth threshold value is the nominal capacity of the battery core in a fourth proportion divided by a preset charging time interval.

According to the scheme for determining the self-discharge of the battery, which is disclosed by one or more embodiments of the invention, whether the battery comprising the battery cells is self-discharged or not can be judged based on the valley phase difference of the battery cells, so that the position of the battery cells where the self-discharge occurs is accurately detected, and the accurate and reliable monitoring of the self-discharge of each battery cell in the battery pack is realized. Furthermore, the scheme for determining battery self-discharge according to one or more embodiments of the present invention enables quantitative analysis of the severity of the battery self-discharge based on the valley phase difference of the battery cells, and corresponding treatment measures associated with the severity of the battery self-discharge to be taken for the battery cells where the self-discharge occurs. Therefore, the accuracy of identifying the self-discharge of the battery is improved, the use safety of the battery is ensured, and the service life of the battery is prolonged.

Drawings

The foregoing and/or other aspects and advantages of the present invention will become more apparent and more readily appreciated from the following description of the various aspects taken in conjunction with the accompanying drawings in which like or similar elements are designated with the same reference numerals. In the drawings:

fig. 1 is a flow diagram of a method for determining self-discharge of a battery in accordance with one or more embodiments of the invention.

Fig. 2 is a graphical illustration of capacity increments of a cell in accordance with one or more embodiments of the present invention.

Fig. 3 is a block diagram of a system for determining battery self-discharge in accordance with one or more embodiments of the present invention.

Detailed Description

The following description of the specific embodiments is merely exemplary in nature and is in no way intended to limit the disclosed technology or the application and uses of the disclosed technology. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, or the following detailed description.

In the following detailed description of embodiments, numerous specific details are set forth in order to provide a more thorough understanding of the disclosed technology. It will be apparent, however, to one skilled in the art that the disclosed techniques may be practiced without these specific details. In other instances, well-known features have not been described in detail so as not to unnecessarily complicate the description.

Terms such as "comprising" and "including" mean that in addition to having elements and steps that are directly and explicitly recited in the description, the inventive aspects also do not exclude the presence of other elements and steps not directly or explicitly recited. The terms such as "first" and "second" do not denote the order of units in terms of time, space, size, etc. but rather are merely used to distinguish one unit from another.

Hereinafter, various exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a flow diagram of a method for determining self-discharge of a battery in accordance with one or more embodiments of the invention.

As shown in fig. 1, in step 101, a capacity increment of a plurality of cells is determined from a charging current and a cell voltage of the plurality of cells in response to the battery being in a slow charge state.

Alternatively, in step 101, it may be determined whether the battery is in a slow charge state based on the charging current value. For example, in the case where the charging current value is smaller than the preset threshold value and the current is stationary, it may be determined that the battery is in a slow charge state. For example, the preset threshold value of the charge current value may be selected to be 1/3C, where 1/3C represents the charge-discharge rate of the battery, which may be calculated by dividing the magnitude of the charge-discharge current by the rated capacity of the battery cell. As an example, when a battery having a rated capacity of 90a·h of a cell is charged and discharged with a current of 30A, the charge/discharge rate thereof is 1/3C. In addition, the charging current value may be used to determine whether the charging current is stable. For example, the charging current value may be acquired within a specific charging period, and the maximum value, the minimum value, and the average value of the acquired charging current value may be calculated. When the ratio of the difference between the maximum value and the minimum value of the charging current values to the average value of the charging current values is smaller than the preset value, it may be determined that the charging current is stationary. By performing the steps of the method for determining the self-discharge of the battery while the battery is in a slow charge state, the accuracy of identifying the self-discharge of the battery is improved.

Optionally, in step 101, determining the capacity increment of the plurality of cells according to the charging current and the cell voltage of the plurality of cells may include: collecting charging currents and cell voltages of a plurality of cells in real time in a battery charging process; low pass filtering (e.g., using a butterworth filter) the acquired cell voltages of the plurality of cells; and determining a capacity increment of the plurality of cells based on the collected charging current of the plurality of cells and the low-pass filtered cell voltage. By low-pass filtering the cell voltages of the collected multiple cells, the accuracy of the calculation of the capacity increment of the cells can be improved.

In one embodiment, the capacity increment of the cell may be calculated by the following equation (1)：

Formula (1)

Wherein,Iindicating the charging current is represented by the number of charging circuits,tandt+1indicating different charging moments, i.e. the firsttTime and the firstt+1At the moment of time of day,V _t is shown in the firsttCell voltage at time, andV _t+1 is shown in the firstt+1Cell voltage at time instant.

In step 103, a valley phase of the plurality of cells at a valley of the capacity increment corresponding to each of the plurality of cells may be determined.

Optionally, in step 103, determining the valley phases of the plurality of cells at the valley of the capacity increment corresponding to each of the plurality of cells may include: determining a plot of the capacity increment of each cell relative to the charge of the cell; determining a local minimum on a curve of the determined capacity increment of each cell relative to the charge amount of the cell as a valley of the capacity increment of each cell; and selecting the charge quantity of the battery cells at the valley value of the capacity increment of each battery cell to generate valley value phases of a plurality of battery cells.

In one embodiment, in determining the local minimum of the capacity increment for each cell, it may be determined whether the capacity increment for the cell is below a valley determination threshold, which may be determined based on a trial calibration. When the capacity increment of the battery core is lower than the valley value judgment threshold value, the capacity increment of the battery core can be determined to reach a local minimum value. By way of example, by calculation of the above formula (1), a curve of the capacity increment of the battery cell with respect to the charge amount of the battery cell can be drawn, the abscissa of the curve being the charge amount of the battery cell, and the ordinate of the curve being the electric cellThe capacity of the core increases. Based on the plotted curve of the capacity increment of the cell with respect to the charge amount of the cell corresponding to each cell, the charge amount of the cell at the valley of the capacity increment of the cell on the curve can be determined as the valley phase Qn of the cell. Illustratively, the charge of the cellQThe calculation can be performed by the following formula (2):

formula (2)

Wherein,Iindicating the charging current is represented by the number of charging circuits,tandt+1indicating different charging moments.

In one embodiment, the valley phase of each cell may be determined using the methods described above in steps 101 and 103. Optionally, the cell number and the charging date of each cell may also be recorded to generate a two-dimensional sequence of valley phases of each cell [ qn_list; index_list; date ], where the qn_list vector represents the valley phase of each cell, the index_list vector represents the cell number of each cell, and date represents the charging date of each cell.

In step 105, a valley phase difference of the plurality of cells may be determined based on the valley phases of the plurality of cells determined in step 103.

Optionally, in step 105, determining the valley phase difference of the plurality of cells based on the valley phases of the plurality of cells may include: determining a valley phase minimum value in the valley phases of the plurality of battery cells; and subtracting the minimum value of the valley phase from the valley phase of the plurality of battery cells respectively to determine the valley phase difference of the plurality of battery cells.

In one embodiment, the valley phase differences of the individual cells may be determined using the method described above in step 105. Optionally, the cell number and the charging date of each cell may also be recorded to generate a two-dimensional sequence of valley phase differences of each cell [ dqn_list; index_list; date ], where the dqn_list vector represents the valley phase differences of each cell, the index_list vector represents the cell number of each cell, and date represents the charging date of each cell. For example, dqn_list can be determined by subtracting qn_min from qn_list, where qn_min is the minimum value in the qn_list vector.

In step 107, it is determined that self-discharge of a battery including one or more of the plurality of battery cells occurs in response to the valley phase difference of the battery cells satisfying a preset condition.

Optionally, in step 107, the preset conditions may include one or more of the following conditions: the valley value phase difference of the battery core is larger than a first threshold value for a preset number of times, wherein the first threshold value is the nominal capacity of the battery core in a first proportion; the valley value phase difference of the battery core is larger than a second threshold value, and the second threshold value is the nominal capacity of the battery core in a second proportion; and the valley phase difference of the battery cells is larger than a third threshold value, the expansion rate of the valley phase difference of the battery cells is larger than a fourth threshold value, the third threshold value is the nominal capacity of the battery cells in a third proportion, and the fourth threshold value is the nominal capacity of the battery cells in a fourth proportion divided by a preset charging time interval.

In one embodiment, the valley phase difference of each cell determined in step 105 may be determined by using the above three conditions, and when any condition is satisfied, it may be determined that the cell is self-discharging.

By way of example, a cell may be determined to self-discharge when the valley phase difference of the cell is greater than 4% of the nominal capacity of the cell for 3 full charges. For example, when the valley phase difference of the cell is greater than 5% of the nominal capacity of the cell, it may be determined that the cell is self-discharging. For example, when the valley phase difference of the cell is greater than 3% of the nominal capacity of the cell and the expansion rate of the valley phase difference of the cell is greater than a fourth threshold, it may be determined that the cell is self-discharging. The expansion rate of the valley phase difference dQn of the battery cell can be calculated by the ratio of the difference dQn2-dQn1 of the valley phase difference dQn of the battery cell charged slowly twice to the time between charging of two times date2-date 1. For example, the fourth threshold may be selected as a ratio of 2% of the nominal capacity of the cell to the time between charges date2-date 1. It should be noted that, the above exemplary selection of the nominal capacity of the battery cell with a specific ratio (e.g., 3%, 4%, 5%) is compared with the valley phase difference of the battery cell as the threshold value to determine whether the battery cell is self-discharged. Under the condition that the spirit and the scope of the invention are not deviated, the nominal capacity of the battery core with other proportions can be selected as a threshold value according to factors such as actual battery use scenes and the like to be compared with the valley phase difference of the battery core so as to judge whether the battery core generates self-discharge or not.

Optionally, in step 107, when it is determined that the cell is self-discharging, a self-discharging alarm signal may be generated, where the self-discharging alarm signal may indicate the number of the cell, the severity of the self-discharging of the cell, and a processing measure associated with the severity of the self-discharging of the cell, so as to prompt a relevant person to perform a corresponding measure on the cell, for example, replacing the cell, repairing the cell, stopping service, and the like. By timely taking treatment measures on the battery core with self-discharge, the safety performance of the battery can be ensured and the service life of the battery can be prolonged.

According to one or more embodiments of the present invention, the self-discharge of the cells can be accurately determined by traversing the valley phase differences of the respective cells based on preset conditions. In addition, the valley phase difference of the battery cell can also quantitatively indicate the severity of the self-discharge of the battery cell, so that treatment measures corresponding to the severity of the self-discharge of the battery cell, such as battery cell replacement, battery cell maintenance, battery cell service stop and the like, can be taken.

It should be noted that the method for determining self-discharge of a battery according to one or more embodiments of the present invention can be applied to determine self-discharge of various lithium batteries, including, but not limited to, lithium iron phosphate batteries, ternary lithium batteries, and the like.

According to the method for determining the self-discharge of the battery, which is provided by one aspect of the invention, whether the battery comprising the battery cells is self-discharged can be judged based on the valley value phase difference of the battery cells, so that the position of the battery cells where the self-discharge occurs is accurately detected, and the accurate and reliable monitoring of the self-discharge of each battery cell in the battery pack is realized. Furthermore, the method for determining the self-discharge of the battery according to one aspect of the present invention enables quantitative analysis of the severity of the self-discharge of the battery based on the valley phase difference of the battery cells, and corresponding treatment measures associated with the severity of the self-discharge of the battery cells are taken for the occurrence of the self-discharge. Therefore, the accuracy of identifying the self-discharge of the battery is improved, the use safety of the battery is ensured, and the service life of the battery is prolonged.

Fig. 2 is a graphical illustration of capacity increments of a cell in accordance with one or more embodiments of the present invention.

As shown in fig. 2, a graph of the capacity increment of the battery cell schematically shows a graph of the capacity increment of the battery cell with respect to the charge amount of the battery cell, the abscissa of the graph being the charge amount Q of the battery cell, and the ordinate of the graph being the capacity increment dQ/dV of the battery cell. In fig. 2, each curve represents the capacity increment dQ/dV of the cell of one cell with respect to the charge amount Q of the cell. By the method for determining self-discharge of a battery according to one or more embodiments of the present invention described in connection with fig. 1, the valley phase difference dQn of each cell can be determined, thereby judging two cells in which self-discharge occurs as shown in fig. 2.

Fig. 3 is a block diagram of a system for determining battery self-discharge in accordance with one or more embodiments of the present invention.

As shown in fig. 3, the system 30 for determining battery self-discharge includes a capacity increment determination module 301, a valley phase determination module 303, a valley phase difference determination module 305, and a judgment module 307.

The capacity increment determination module 301 is configured to determine a capacity increment of the plurality of battery cells from the charging current and the battery cell voltage of the plurality of battery cells in response to the battery being in a slow charge state.

Alternatively, the capacity increment determination module 301 may be configured to determine whether the battery is in a slow charge state based on the charge current value. For example, in the case where the charging current value is smaller than the preset threshold value and the current is stationary, it may be determined that the battery is in a slow charge state. For example, the preset threshold value of the charging current value may be selected to be 1/3C. In addition, the charging current value may be used to determine whether the charging current is stable. For example, the charging current value may be acquired within a specific charging period, and the maximum value, the minimum value, and the average value of the acquired charging current value may be calculated. When the ratio of the difference between the maximum value and the minimum value of the charging current values to the average value of the charging current values is smaller than the preset value, it may be determined that the charging current is stationary.

Alternatively, the capacity increment determination module 301 may be configured to: collecting charging currents and cell voltages of a plurality of cells in real time in a battery charging process; low pass filtering (e.g., using a butterworth filter) the acquired cell voltages of the plurality of cells; and determining a capacity increment of the plurality of cells based on the collected charging current of the plurality of cells and the low-pass filtered cell voltage. By low-pass filtering the cell voltages of the collected multiple cells, the accuracy of the calculation of the capacity increment of the cells can be improved.

The valley phase determination module 303 may be configured to determine the valley phases of the plurality of cells at the valley of the capacity delta corresponding to each of the plurality of cells.

Alternatively, the valley phase determination module 303 may be configured to: determining a plot of the capacity increment of each cell relative to the charge of the cell; determining a local minimum on a curve of the determined capacity increment of each cell relative to the charge amount of the cell as a valley of the capacity increment of each cell; and selecting the charge quantity of the battery cells at the valley value of the capacity increment of each battery cell to generate valley value phases of a plurality of battery cells.

In one embodiment, in determining the local minimum of the capacity increment for each cell, it may be determined whether the capacity increment for the cell is below a valley determination threshold, which may be determined based on a trial calibration. When the capacity increment of the battery core is lower than the valley value judgment threshold value, the capacity increment of the battery core can be determined to reach a local minimum value. By way of example, by calculation of the above formula (1), a curve of the capacity increment of the battery cell with respect to the charge amount of the battery cell can be drawn, the abscissa of the curve being the charge amount of the battery cell, and the ordinate of the curve being the capacity increment of the battery cell. Based on the plotted curve of the capacity increment of the cell with respect to the charge amount of the cell corresponding to each cell, the charge amount of the cell at the valley of the capacity increment of the cell on the curve can be determined as the valley phase Qn of the cell.

The valley phase difference determination module 305 may be configured to determine the valley phase differences of the plurality of cells based on the valley phases of the plurality of cells determined by the valley phase determination module 303.

Alternatively, the valley phase difference determination module 305 may be configured to: determining a valley phase minimum value in the valley phases of the plurality of battery cells; and subtracting the minimum value of the valley phase from the valley phase of the plurality of battery cells respectively to determine the valley phase difference of the plurality of battery cells.

The determination module 307 may be configured to determine that self-discharge of the battery including the battery cells occurs in response to the valley phase difference of one or more battery cells among the plurality of battery cells satisfying a preset condition.

Alternatively, the preset conditions may include one or more of the following conditions: the valley value phase difference of the battery core is larger than a first threshold value for a preset number of times, wherein the first threshold value is the nominal capacity of the battery core in a first proportion; the valley value phase difference of the battery core is larger than a second threshold value, and the second threshold value is the nominal capacity of the battery core in a second proportion; and the valley phase difference of the battery cells is larger than a third threshold value, the expansion rate of the valley phase difference of the battery cells is larger than a fourth threshold value, the third threshold value is the nominal capacity of the battery cells in a third proportion, and the fourth threshold value is the nominal capacity of the battery cells in a fourth proportion divided by a preset charging time interval.

In one embodiment, for the valley phase difference of each cell determined by the valley phase difference determining module 305, the determining module 307 may determine that the cell generates self-discharge by using the three conditions as described above, and when any condition is satisfied.

By way of example, a cell may be determined to self-discharge when the valley phase difference of the cell is greater than 4% of the nominal capacity of the cell for 3 full charges. For example, when the valley phase difference of the cell is greater than 5% of the nominal capacity of the cell, it may be determined that the cell is self-discharging. For example, when the valley phase difference of the cell is greater than 3% of the nominal capacity of the cell and the expansion rate of the valley phase difference of the cell is greater than a fourth threshold, it may be determined that the cell is self-discharging. The expansion rate of the valley phase difference dQn of the battery cell can be calculated by the ratio of the difference dQn2-dQn1 of the valley phase difference dQn of the battery cell charged slowly twice to the time between charging of two times date2-date 1. For example, the fourth threshold may be selected as a ratio of 2% of the nominal capacity of the cell to the time between charges date2-date 1. It should be noted that, the above exemplary selection of the nominal capacity of the battery cell with a specific ratio (e.g., 3%, 4%, 5%) is compared with the valley phase difference of the battery cell as the threshold value to determine whether the battery cell is self-discharged. Under the condition that the spirit and the scope of the invention are not deviated, the nominal capacity of the battery core with other proportions can be selected as a threshold value according to factors such as actual battery use scenes and the like to be compared with the valley phase difference of the battery core so as to judge whether the battery core generates self-discharge or not.

Optionally, the determining module 307 may be further configured to generate a self-discharge alarm signal when the determining module determines that the cell is self-discharged, where the self-discharge alarm signal may indicate the number of the cell, the severity of the self-discharge of the cell, and a processing measure associated with the severity of the self-discharge of the cell, so as to prompt a relevant person to perform a corresponding measure on the cell, such as replacing the cell, maintaining the cell, stopping service, and so on. By timely taking treatment measures on the battery core with self-discharge, the safety performance of the battery can be ensured and the service life of the battery can be prolonged.

According to one or more embodiments of the present invention, the determination module 307 may accurately determine the self-discharge of the cells by traversing the valley phase differences of the respective cells based on the preset conditions. In addition, the valley phase difference of the battery cell can also quantitatively indicate the severity of the self-discharge of the battery cell, so that treatment measures corresponding to the severity of the self-discharge of the battery cell, such as battery cell replacement, battery cell maintenance, battery cell service stop and the like, can be taken.

It should be noted that the system for determining self-discharge of a battery according to one or more embodiments of the present invention can be adapted to determine self-discharge of various lithium batteries, including, but not limited to, lithium iron phosphate batteries, ternary lithium batteries, and the like.

According to the system for determining the self-discharge of the battery, which is provided by the invention, whether the battery comprising the battery cells is self-discharged or not can be judged based on the valley value phase difference of the battery cells, so that the position of the battery cells where the self-discharge occurs is accurately detected, and the accurate and reliable monitoring of the self-discharge of each battery cell in the battery pack is realized. Furthermore, the system for determining battery self-discharge according to one aspect of the present invention is capable of quantitatively analyzing the severity of battery self-discharge based on the valley phase difference of the battery cells, and taking corresponding treatment measures associated with the severity of battery self-discharge for the battery cells where self-discharge occurs. Therefore, the accuracy of identifying the self-discharge of the battery is improved, the use safety of the battery is ensured, and the service life of the battery is prolonged.

It should be noted that the method for determining self-discharge of a battery and the system for determining self-discharge of a battery according to one or more aspects of the present invention may be deployed in a vehicle end (e.g., a battery management system of a vehicle), a cloud end, a combination of a vehicle end and a cloud end.

Where applicable, hardware, software, or a combination of hardware and software may be used to implement the various embodiments provided by the present invention. Moreover, where applicable, the various hardware components and/or software components set forth herein may be combined into composite components comprising software, hardware, and/or both without departing from the scope of the present invention. Where applicable, the various hardware components and/or software components set forth herein can be separated into sub-components comprising software, hardware, or both without departing from the scope of the present invention. Further, where applicable, it is contemplated that software components may be implemented as hardware components, and vice versa.

Software in accordance with the present invention, such as program code and/or data, may be stored on one or more computer storage media. It is also contemplated that the software identified herein may be implemented using one or more general-purpose or special-purpose computers and/or computer systems that are networked and/or otherwise. Where applicable, the order of the various steps described herein may be changed, combined into composite steps, and/or divided into sub-steps to provide features described herein.

The embodiments and examples set forth herein are presented to best explain the embodiments consistent with the invention and its particular application and to thereby enable those skilled in the art to make and use the invention. However, those skilled in the art will recognize that the foregoing description and examples have been presented for the purpose of illustration and example only. The description as set forth is not intended to cover various aspects of the invention or to limit the invention to the precise form disclosed.

Claims (12)

1. A method for determining self-discharge of a battery, the method comprising the steps of:

determining a capacity increment of the plurality of cells from the charging current and the cell voltage of the plurality of cells in response to the battery being in a slow charge state;

determining a valley phase of the plurality of cells at a valley of a capacity increment corresponding to each of the plurality of cells;

determining a valley phase difference of the plurality of cells based on the valley phases of the plurality of cells; and

and judging that the battery comprising the battery cells is self-discharged in response to the valley phase difference of one or more battery cells in the valley phase differences of the battery cells meeting a preset condition.

2. The method of claim 1, wherein the slow charge state is determined based on a charge current value.

3. The method of claim 1, wherein determining the capacity increment of the plurality of cells from the charge current and the cell voltage of the plurality of cells comprises:

collecting charging currents and cell voltages of a plurality of cells in real time in a battery charging process;

performing low-pass filtering on the acquired cell voltages of the multiple cells; and

the capacity increment of the plurality of battery cells is determined based on the collected charging currents of the plurality of battery cells and the low-pass filtered battery cell voltage.

4. The method of claim 1, wherein determining a valley phase of the plurality of cells at a valley of a capacity delta corresponding to each of the plurality of cells comprises:

determining a plot of the capacity increment of each cell relative to the charge of the cell;

determining a local minimum on a curve of the determined capacity increment of each cell relative to the charge amount of the cell as a valley of the capacity increment of each cell; and

and selecting the charge quantity of the battery cells at the valley value of the capacity increment of each battery cell to generate valley value phases of a plurality of battery cells.

5. The method of claim 1, wherein determining a valley phase difference for a plurality of cells based on a valley phase of the plurality of cells comprises:

determining a valley phase minimum value of the valley phases of the plurality of battery cells; and

and subtracting the minimum value of the valley phases of the plurality of electric cores respectively to determine the valley phase difference of the plurality of electric cores.

6. The method of claim 1, wherein the preset conditions include one or more of:

the valley value phase difference of the battery cell is larger than a first threshold value for a preset number of times, wherein the first threshold value is the nominal capacity of the battery cell in a first proportion;

the valley value phase difference of the battery cell is larger than a second threshold value, and the second threshold value is the nominal capacity of the battery cell in a second proportion; and

the valley phase difference of the battery cell is larger than a third threshold value, the expansion rate of the valley phase difference of the battery cell is larger than a fourth threshold value, the third threshold value is the nominal capacity of the battery cell in a third proportion, and the fourth threshold value is the nominal capacity of the battery cell in a fourth proportion divided by a preset charging time interval.

7. A system for determining self-discharge of a battery, the system comprising:

a capacity increment determination module configured to determine a capacity increment of the plurality of battery cells from the charging current and the battery cell voltage of the plurality of battery cells in response to the battery being in a slow charge state;

a valley phase determination module configured to determine valley phases of a plurality of cells at a valley of a capacity delta corresponding to each of the plurality of cells;

a valley phase difference determination module configured to determine a valley phase difference of the plurality of cells based on the valley phases of the plurality of cells; and

a determination module configured to determine that self-discharge of a battery including the battery cells occurs in response to a valley phase difference of one or more of the plurality of battery cells satisfying a preset condition.

8. The system of claim 7, wherein the slow charge state is determined based on a charge current value.

9. The system of claim 7, wherein the capacity increment determination module is further configured to:

collecting charging currents and cell voltages of a plurality of cells in real time in a battery charging process;

performing low-pass filtering on the acquired cell voltages of the multiple cells; and

the capacity increment of the plurality of battery cells is determined based on the collected charging currents of the plurality of battery cells and the low-pass filtered battery cell voltage.

10. The system of claim 7, wherein the valley phase determination module is further configured to:

determining a plot of the capacity increment of each cell relative to the charge of the cell;

determining a local minimum on a curve of the determined capacity increment of each cell relative to the charge amount of the cell as a valley of the capacity increment of each cell; and

and selecting the charge quantity of the battery cells at the valley value of the capacity increment of each battery cell to generate valley value phases of a plurality of battery cells.

11. The system of claim 7, wherein the valley phase difference determination module is further configured to:

determining a valley phase minimum value of the valley phases of the plurality of battery cells; and

and subtracting the minimum value of the valley phases of the plurality of electric cores respectively to determine the valley phase difference of the plurality of electric cores.

12. The system of claim 7, wherein the preset conditions include one or more of:

the valley value phase difference of the battery cell is larger than a first threshold value for a preset number of times, wherein the first threshold value is the nominal capacity of the battery cell in a first proportion;

the valley value phase difference of the battery cell is larger than a second threshold value, and the second threshold value is the nominal capacity of the battery cell in a second proportion; and

the valley phase difference of the battery cell is larger than a third threshold value, the expansion rate of the valley phase difference of the battery cell is larger than a fourth threshold value, the third threshold value is the nominal capacity of the battery cell in a third proportion, and the fourth threshold value is the nominal capacity of the battery cell in a fourth proportion divided by a preset charging time interval.