CN112394290A

CN112394290A - Method and device for estimating SOH of battery pack, computer equipment and storage medium

Info

Publication number: CN112394290A
Application number: CN201910758183.6A
Authority: CN
Inventors: 严丽; 周莎; 陈斌; 张传龙
Original assignee: Thornton New Energy Technology Changsha Co ltd
Current assignee: Yuyao Haitai Trading Co ltd
Priority date: 2019-08-16
Filing date: 2019-08-16
Publication date: 2021-02-23
Anticipated expiration: 2039-08-16
Also published as: CN112394290B

Abstract

The application relates to a method, a device, a computer device and a storage medium for estimating SOH of a battery pack, wherein the method comprises the following steps: acquiring monomer state information of each monomer battery cell when the battery pack is in a first preset state; acquiring accumulated capacitance data of the battery pack in the process from a first preset state to a second preset state, wherein the first preset state is a state before the battery pack is discharged, the second preset state is a state after the battery pack is discharged or the first preset state is a state before the battery pack is charged, and the second preset state is a state after the battery pack is charged; extracting monomer state information of a target monomer battery cell in a first preset state to serve as a first state parameter; acquiring monomer state information of the target monomer battery cell in a second preset state as a second state parameter; and calculating according to the first state parameter, the second state parameter, the preset nominal capacitance and the accumulated capacitance data to obtain the SOH of the battery pack. By adopting the method, the more accurate SOH value of the battery pack can be calculated.

Description

Method and device for estimating SOH of battery pack, computer equipment and storage medium

Technical Field

The present application relates to the field of battery detection technologies, and in particular, to a method and an apparatus for detecting an SOH of a battery pack, a computer device, and a storage medium.

Background

During the long-term use Of a power battery Of an electric vehicle, the capacity, performance and the like Of the battery are continuously attenuated, and the SOH (State Of Health, referred to as Health State for short) Of the power battery represents the capacity, Health degree and performance State Of the battery, reflects the Health State Of the battery and is also one Of the key parameters Of the electric vehicle, so the SOH Of the battery needs to be estimated to know the real-time condition Of the electric vehicle.

However, the conventional method for estimating the SOH of the battery pack generally refers to the cycle life curve of the battery pack, and finds the SOH state of the current battery pack according to the cycle number of the current battery pack. The method has the problems that the working conditions of the battery pack are irregular in the using process, the cycle life curve of the battery pack is obtained by testing according to a certain working condition, and the SOH of the battery pack is greatly influenced by different working conditions, so that the deviation of the finally estimated SOH of the battery pack is large, and the SOH of the battery pack cannot be accurately estimated.

Disclosure of Invention

Based on this, it is necessary to provide an estimation method, an apparatus, a computer device, and a storage medium capable of accurately estimating the SOH of the battery pack, in view of the problem that the SOH estimation method of the battery pack is inaccurate.

A method of estimating SOH of a battery pack, the method comprising the steps of:

acquiring monomer state information of each monomer battery cell when the battery pack is in a first preset state;

acquiring accumulated capacitance data of the battery pack in the process from a first preset state to a second preset state, wherein the first preset state is a state before the battery pack is discharged, the second preset state is a state after the battery pack is discharged, or the first preset state is a state before the battery pack is charged, and the second preset state is a state after the battery pack is charged;

acquiring a single battery cell which meets a preset condition in a battery pack in a second preset state, and taking the single battery cell as a target single battery cell;

extracting monomer state information of a target monomer battery cell in a first preset state to serve as a first state parameter;

acquiring monomer state information of the target monomer battery cell in a second preset state as a second state parameter;

and calculating according to the first state parameter, the second state parameter, the preset nominal capacitance and the accumulated capacitance data to obtain the SOH of the battery pack.

According to the estimation method of the SOH of the battery pack, the parameter change of the target single battery cell in the battery pack from the first preset state to the second preset state is searched, specifically, the parameter change of the target single battery cell meeting the preset conditions in the battery pack from before charging to after charging or before discharging to after discharging is searched, and then the SOH of the battery pack is calculated according to the parameter change of the target single battery cell, so that the calculation of the SOH value of the battery pack can be more accurate, the more accurate SOH value is obtained, and effective data support can be improved for performance estimation of a subsequent electric vehicle.

In one embodiment, the cell state information includes an SOC correction value.

The SOC value of the single battery cell is corrected to obtain the SOC correction value, and the SOC correction value is included in the single state information, so that the more accurate single state information of the single battery cell can be obtained, and errors are effectively eliminated.

In one embodiment, the cell state information includes an SOC correction value and a charge level, and the cell state information of each cell in the battery pack in the first preset state is collected, which specifically includes the following steps:

acquiring open-circuit voltage of each single battery cell;

acquiring an SOC value corresponding to the open-circuit voltage of each single battery cell according to a preset OCV table, and taking the SOC value as an SOC correction value of each single battery cell in a first preset state;

and determining the charge level of each single battery cell in a first preset state according to the SOC correction value.

The SOC correction value of each single battery cell is determined by presetting the OCV table, the accuracy of the SOC correction value can be ensured, accurate charge levels can be further obtained according to the SOC correction value, and the single state information corresponding to the target single battery cell can be conveniently and directly searched from each single battery cell in the follow-up process, so that the calculation accuracy of the SOH value can be ensured in the follow-up process of calculating the SOH value of the battery pack.

In one embodiment, acquiring cell state information of the target cell in a second preset state as a second state parameter specifically includes the following steps:

collecting the open-circuit voltage of a target single battery cell;

acquiring an SOC value corresponding to the open-circuit voltage of the target single battery cell in a second preset state according to a preset OCV table, and taking the SOC value as an SOC correction value of the target single battery cell in the second preset state;

and determining the charge level of the target single battery cell in a second preset state according to the SOC corrected value of the target single battery cell.

Through SOC corrected value and the charge level of the target single battery cell in the second preset state, more effective data support can be provided, and through obtaining accurate charge level data, the influence of the charge level on accumulated capacitance data can be reduced, so that the calculation of the SOH value of a subsequent battery pack is more accurate.

In one embodiment, calculating according to the first state parameter, the second state parameter and the accumulated capacitance data to obtain the SOH of the battery pack specifically includes the following steps:

acquiring a grade difference value between the charge grade of the target monomer battery cell in the second preset state and the charge grade of the target monomer battery cell in the first preset state;

judging whether the grade difference value exceeds a preset threshold value or not;

if so, calculating according to the SOC corrected value of the target single battery cell in the second preset state, the SOC corrected value of the target single battery cell in the first preset state, the preset nominal capacitance and the accumulated capacitance data to obtain the SOH of the battery pack.

The target single battery cell has different charge levels when in the first preset state and the second preset state, and the charge levels have certain influence on the accumulated capacitance data, so that calculation errors exist in the accumulated capacitance data, the error influence can be eliminated by judging the level difference, the calculation errors of subsequent SOH values of the battery pack caused by the calculation errors of the accumulated capacitance data are prevented, and the calculation accuracy of the SOH values of the battery pack is ensured.

In one embodiment, before acquiring cell state information of each cell in the battery pack in the first preset state, the method further includes the following steps:

judging whether the battery pack meets a preset OCV correction condition or not;

if so, the step of acquiring the monomer state information of each monomer electric core when the battery pack is in the first preset state is carried out.

Only when the battery pack meets the preset OCV correction condition, the acquired monomer state information can be ensured not to have errors, and the accuracy of data is ensured.

In one embodiment, after acquiring the accumulated capacitance data of the battery pack during the process from the first preset state to the second preset state, the method further includes the following steps before acquiring the cell satisfying the preset condition in the second preset state of the battery pack, and before taking the cell as the target cell:

judging whether the battery pack meets a preset correction condition in a second preset state;

if so, entering a step of acquiring the single electric core which meets the preset condition in the battery pack when the battery pack is in the second preset state, and taking the single electric core as a target single electric core.

The preset correction conditions can be various, and different monomer state information of the target monomer electric core in the second preset state can be obtained subsequently according to different preset correction conditions, so that the accuracy of data under different preset correction conditions is ensured.

An apparatus for estimating SOH of a battery pack, the apparatus comprising:

the information acquisition module is used for acquiring monomer state information of each monomer battery cell when the battery pack is in a first preset state;

the battery pack control device comprises a capacitance acquisition module, a storage module and a control module, wherein the capacitance acquisition module is used for acquiring accumulated capacitance data of the battery pack in the process from a first preset state to a second preset state;

the battery cell determining module is used for acquiring the single battery cells which meet preset conditions in the battery pack when the battery pack is in a second preset state, and using the single battery cells as target single battery cells;

the first parameter determination module is used for extracting monomer state information of a target monomer battery cell in a first preset state to serve as a first state parameter;

the second parameter determination module is used for acquiring monomer state information of the target monomer battery cell in a second preset state as a second state parameter;

and the calculation module is used for calculating according to the first state parameter, the second state parameter, the preset nominal capacitance and the accumulated capacitance data to obtain the SOH of the battery pack.

Above-mentioned estimation device of battery package SOH, through the parameter variation when seeking the target monomer electric core in the battery package from first preset state to second preset state, it is concrete, through the parameter variation before the target monomer electric core that satisfies the preset condition in seeking the battery package charges to the back of charging or before discharging to the back of discharging, then according to the parameter variation of target monomer electric core, calculate the SOH who obtains the battery package, can make the calculation of battery package SOH value more accurate, obtain more accurate SOH value, thereby can improve effectual data support for follow-up electric automobile's performance estimation.

A computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor realizes the steps of the estimation method of the SOH of the battery pack when executing the computer program.

According to the computer equipment, parameter change when the target single battery cell in the battery pack is searched from the first preset state to the second preset state is achieved, specifically, parameter change before charging or after discharging or before discharging to after discharging of the target single battery cell meeting preset conditions in the battery pack is searched, and then according to the parameter change of the target single battery cell, SOH of the battery pack is obtained through calculation, calculation of the SOH value of the battery pack can be more accurate, the more accurate SOH value is obtained, and effective data support can be improved for performance estimation of a follow-up electric vehicle.

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 above-mentioned method of estimating the SOH of a battery pack.

According to the computer-readable storage medium, parameter changes of target single battery cells in the battery pack from a first preset state to a second preset state are searched, specifically, parameter changes of the target single battery cells meeting preset conditions in the battery pack from before charging to after charging or from before discharging to after discharging are searched, and then according to the parameter changes of the target single battery cells, SOH of the battery pack is obtained through calculation, so that calculation of SOH values of the battery pack can be more accurate, more accurate SOH values are obtained, and effective data support can be improved for performance estimation of subsequent electric vehicles.

Drawings

FIG. 1 is a diagram illustrating an exemplary embodiment of a method for estimating SOH of a battery pack;

FIG. 2 is a flow chart illustrating a method for estimating SOH of a battery pack according to an embodiment;

FIG. 3 is a flow chart illustrating a method for estimating SOH of a battery pack according to one embodiment;

FIG. 4 is a flow chart illustrating a method for estimating SOH of a battery pack according to another embodiment;

FIG. 5 is a block diagram showing an example of the structure of the evaluation device of the battery pack S0H;

FIG. 6 is a flow diagram of a method for estimating SOH of a battery pack in a discharging mode according to one embodiment;

FIG. 7 is a flow chart of a method for estimating SOH of a battery pack in a charging mode according to one embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

The method for estimating the SOH of the battery pack can be applied to the application environment shown in FIG. 1. The terminal 101 is connected to a battery pack 103. The terminal 101 may execute a computer program stored therein, and when the computer program is executed, the steps of the method for estimating the SOH of the battery pack are implemented, and finally the SOH value of the battery pack is obtained, where the SOH value may be directly displayed by the terminal 101, or the terminal 101 may send the SOH value to a corresponding display device for displaying.

In one embodiment, as shown in fig. 2, a method for estimating SOH of a battery pack is provided, which is described by taking the method as an example applied to the terminal in fig. 1, and includes the following steps:

step S120: the method comprises the steps of collecting monomer state information of each monomer battery cell when the battery pack is in a first preset state.

Specifically, the terminal may collect cell State information through a corresponding device, such as a power detection device, and the like, where the cell State information may be a corrected SOC value of a cell in the battery (SOC is called State of Charge, and also called remaining power, and represents a ratio of a remaining capacity of the battery after being used for a period of time or after being left unused for a long time to a capacity of a full Charge State thereof, where a common percentage represents a value range of the SOC value from 0 to 1, where SOC is 0, indicates that the battery is completely discharged, and SOC is 1, indicates that the battery is completely charged), where the SOC correction value in this embodiment represents a correction value of the remaining power of one cell rather than a remaining power value of the entire battery pack, and the collection of the cell State information may be implemented by combining a corresponding collection device or a corresponding collection device with collection software on the terminal, so as to collect the cell State information, for example, in one embodiment, the open-circuit voltage of the battery cell may be collected by a BMS system, and then a comparative SOC correction value is obtained from a preset OCV table according to the open-circuit voltage, where the SOC correction value is different from a remaining power value, the SOC correction value is obtained by correcting the SOC correction value through the preset OCV table, and it is the remaining power value that is not corrected through the preset OCV table, and the accuracy of the remaining power value is not as high as that of the SOC correction value, and the BMS system is a battery management system that is a conventional system and will not be described in detail herein.

It should be noted that, the battery pack is formed by connecting a plurality of battery cells in series and in parallel, taking a battery pack formed by three battery cells as an example, in a use process of the battery pack, performance of the three battery cells may be different, so that consistency is different, one of the battery cells may be the worst one, and the one battery cell has the largest influence on overall performance of the battery pack. The acquired monomer state information can be stored in the terminal in a corresponding form, for example, the monomer electric core and the corresponding monomer state information can be stored in a form of a preset form, so that subsequent calling is facilitated.

Step S130: and acquiring accumulated capacitance data of the battery pack in the process from the first preset state to the second preset state. The first preset state is a state before the battery pack is discharged, the second preset state is a state after the battery pack is discharged, or the first preset state is a state before the battery pack is charged, and the second preset state is a state after the battery pack is charged.

Specifically, when the first preset state is a state before the battery pack is discharged, the second preset state corresponds to a state after the battery pack is discharged, and the accumulated capacitance data represents the accumulated discharge amount of the battery pack; when the first preset state is a pre-charging state of the battery pack, the second preset state corresponds to a post-charging state of the battery pack, and the accumulated capacitance data represents an accumulated charging amount of the battery pack.

It should be noted that, if the accumulated capacitance data is an accumulated discharge amount, when the accumulated discharge amount is obtained, the device may automatically control the battery pack to perform discharge, for example, the battery pack supplies power to a high-power bulb to perform discharge, so as to obtain the accumulated discharge amount, and accordingly, when the accumulated capacitance data is an accumulated charge amount, when the accumulated charge amount is obtained, the device may automatically control the battery pack to perform charge, for example, an existing charging pile, so as to obtain the accumulated charge amount.

Step S150: and acquiring the single battery cell which meets the preset condition in the battery pack when the battery pack is in the second preset state, and taking the single battery cell as the target single battery cell.

Specifically, as mentioned in step S130, the second preset state may be a post-discharge state of the battery pack or a post-charge state of the battery pack. Therefore, the preset condition in step S150 may correspond to two different situations according to the difference of the second preset state, and when the second preset state in step S130 is the state after the battery pack is discharged, the preset condition corresponds to the lowest voltage of the cells, that is, the target cell is the cell with the lowest voltage in the battery pack at this time; when the second preset state in step S130 is the state after the battery pack is charged, the preset condition corresponds to the highest voltage of the cell, that is, the target cell is the cell with the highest voltage in the battery pack.

And when the preset condition is the lowest cell voltage, the target cell is the cell with the lowest voltage. Correspondingly, when the preset condition is the monomer maximum voltage, the target monomer electric core is the electric core with the highest voltage, no matter which condition, the target monomer electric core is the electric core with the worst consistency in all the monomer electric cores of the battery pack, and the target monomer electric core with the worst consistency is searched, so that the calculation of the SOH value of the battery pack according to the state parameters of the target monomer electric core can be more accurate, and the accuracy of data is improved.

It should be noted that all the single battery cells in the battery pack may be measured by voltage measuring equipment or software such as a BMS system, and after the voltages of all the single battery cells are measured, the highest voltage battery cell and the lowest voltage battery cell can be determined, and the highest voltage battery cell or the lowest voltage battery cell is the target single battery cell.

Step S160: and extracting the monomer state information of the target monomer battery cell in a first preset state as a first state parameter.

Specifically, the cell state information may be an SOC correction value of the cell, and the first preset state may be a state before discharging of the battery pack or a state after charging of the battery pack. In step S120, the cell state information of all the cell electric cores in the first preset state is already obtained, so in step S170, only the target cell electric core needs to be found from all the cell electric cores, and then the cell state information of the target cell electric core in the first preset state is extracted. For example, when the cell state information of all the cell electric cores in the first preset state is stored in the preset table in step S120, the terminal may directly find the target cell electric core from the preset table, and then extract the corresponding cell state information as the first state parameter.

Step S170: and acquiring monomer state information of the target monomer battery cell in a second preset state as a second state parameter.

Specifically, the cell state information may be an SOC correction value of the cell, and when the second preset state is a state after discharge of the battery pack, the second state parameter is the SOC correction value of the target cell after discharge; when the second preset state is a state after the battery pack is charged, the second state parameter is an SOC correction value of the target cell after charging, wherein the SOC value of the target cell may be collected by the electric quantity detection device and then uploaded to the terminal.

Step S180: and calculating according to the first state parameter, the second state parameter, the preset nominal capacitance and the accumulated capacitance data to obtain the SOH of the battery pack.

Specifically, the preset nominal capacitance is a nominal capacitance of the battery pack when the battery pack leaves a factory newly, and different preset nominal capacitances may exist when different types of battery packs leave the factory. It should be noted that, when calculating the SOH of the battery pack, a calculation formula may be adopted

In the calculation formula, Cdischg represents the accumulated capacitance data, and socow 1 represents that the target monomer cell is in the second preset stateThe second state parameter at state, SOClow0, represents the first state parameter of the target cell at the first preset state, and Cfresh represents the preset nominal capacitance.

In one embodiment, as shown in fig. 3, the cell state information includes an SOC correction value and a charge level, and in the method, the step S120 specifically includes a step S121, a step S122, and a step S123.

Step S121: and acquiring the open-circuit voltage of each single battery cell. Specifically, the terminal can acquire the open-circuit voltage of each single battery cell through the BMS system, and then acquire the data information of the open-circuit voltage from the BMS system.

Step S122: and acquiring SOC correction values corresponding to the open-circuit voltages of the monomer battery cells according to a preset OCV table, wherein the SOC correction values are used as SOC correction values of the monomer battery cells in a first preset state. Specifically, the preset OCV table is a relationship between the open-circuit voltage of the single cell after standing for 2 hours and the cell residual capacity (the residual capacity value of the cell is the SOC value of the cell), the preset OCV table can play a role in correcting the cell SOC value, namely, the corresponding SOC correction value in the preset OCV table is obtained according to the corresponding open-circuit voltage, the collected cell SOC value is prevented from generating errors, and the terminal can obtain the SOC correction value corresponding to each single cell from the preset OCV table after obtaining the open-circuit voltage data of each single cell.

Step S123: and determining the charge level of each single battery cell in a first preset state according to the SOC correction value. Specifically, the SOC correction value of each cell may be different, wherein the charge levels may be divided into a low charge level, a medium charge level, and a high charge level, for example, when the SOC correction value of a cell is less than or equal to 20%, the cell is determined as the low charge level, when the SOC correction value of a cell is between 20% and 80%, the cell is determined as the medium charge level, and when the SOC correction value of a cell is greater than or equal to 80%, the cell is determined as the high charge level. It should be understood that, by determining which charge level the single cell is at, the influence of the accumulated capacitance data on the calculation of the SOH value can be reduced, and the calculation accuracy of the SOH value can be improved.

In one embodiment, as shown in fig. 3, in the method, the step S170 specifically includes a step S171, a step S172, and a step S173.

Step S171: and collecting the open-circuit voltage of the target single battery cell. Specifically, after the target individual cell is determined, the terminal may directly acquire the open-circuit voltage of the target individual cell through the BMS system and the like.

Step S172: and acquiring an SOC value corresponding to the open-circuit voltage of the target single battery cell in a second preset state according to the preset OCV table, and taking the SOC value as an SOC correction value of the target single battery cell in the second preset state. The obtaining of the SOC correction value of the target individual battery cell is similar to the obtaining of the SOC correction value of each individual battery cell in step S122, and details are not described here.

Step S173: and determining the charge level of the target single battery cell in a second preset state according to the SOC corrected value of the target single battery cell. The determination of the charge level of the target cell in the second preset state is similar to step S123, and is not described in detail herein.

Through the SOC correction value and the charge level of the target single battery cell in the second preset state, more effective data support can be provided, the influence of the charge level on the accumulated capacitance data is reduced, and the calculation of the SOH value of the subsequent battery pack is more accurate.

In one embodiment, as shown in fig. 3, in the method, step S180 specifically includes step S181, step S182, and step S183.

Step S181: and acquiring a grade difference value between the charge grade of the target single battery cell in the second preset state and the charge grade of the target single battery cell in the first preset state. Specifically, when the preset charge level of the target monomer electric core in the second preset state is a high charge level, and the preset charge level in the first preset state is a low charge level, the level difference may be defined as a second level, and correspondingly, the level difference may also be a first level or a zero level.

Step S182: and judging whether the grade difference value exceeds a preset threshold value. Specifically, the preset threshold may be defined as one level, and when the level difference is two levels, the preset threshold is exceeded.

Step S183: if so, calculating according to the SOC corrected value of the target single battery cell in the second preset state, the SOC corrected value of the target single battery cell in the first preset state, the preset nominal capacitance and the accumulated capacitance data to obtain the SOH of the battery pack.

In one embodiment, as shown in fig. 4, before step S120, the method further comprises step S110.

Step S110: and judging whether the battery pack meets a preset OCV correction condition, if so, turning to the step S120.

Specifically, the preset OCV correction condition may be that the battery pack is left standing for two hours, and if the battery pack does not satisfy the condition of being left standing for two hours, the SOC correction value obtained by the preset OCV table is prone to have an error.

In one embodiment, as shown in fig. 4, after step S130, before step S150, the method further comprises step S140.

Step S140: judging whether the battery pack meets a preset correction condition in a second preset state; if yes, go to step 150. Specifically, the preset correction condition may be a preset OCV correction condition, a full discharge correction condition, or a full charge correction condition, when the second preset state is a state after the battery pack is discharged, the preset correction condition includes the preset OCV correction condition or the full discharge correction condition, and when the second preset state is the state after the battery pack is charged, the preset correction condition includes the preset OCV correction condition or the full charge correction condition.

The preset OCV correction condition can be that the battery pack is kept still for two hours; the full discharge correction condition may be that, during discharge, when the voltage of the single cell with the lowest voltage (i.e., the target single cell) reaches the lower cell voltage use limit, the SOC of the battery pack is directly corrected to 0%; the full charge correction condition may be that, when the cell voltage of the highest cell (i.e., the target cell) reaches the upper cell voltage use limit during charging, the SOC of the battery pack is directly corrected to 100%.

It should be noted that, when the second preset state is a post-discharge state of the battery pack, in step S160, the cell state information of the target cell in the second preset state may be an SOC correction value, and if the battery pack satisfies the full discharge correction condition in step S150, the SOC correction value of the cell with the lowest voltage (i.e., the target cell) is 0%; when the second preset state is the post-charge state of the battery pack, if the battery pack satisfies the full charge correction condition in step S150, the SOC correction value of the cell (i.e., the target cell) with the highest voltage is 100%.

It should be understood that although the various steps in the flow charts of fig. 2-4 are shown in order as indicated by the arrows, the steps are not necessarily performed in order 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 some of the steps in fig. 2-4 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternating with other steps or at least some of the sub-steps or stages of other steps.

In one embodiment, as shown in fig. 5, an estimation apparatus for SOH of a battery pack is provided, which includes an information acquisition module 120, a capacitance acquisition module 130, a cell determination module 150, a first parameter determination module 160, a second parameter determination module 170, and a calculation module 180.

The information collecting module 120 is configured to collect cell state information of each cell when the battery pack is in a first preset state.

The capacitance obtaining module 130 is configured to obtain accumulated capacitance data of the battery pack during a process from a first preset state to a second preset state.

The cell determining module 150 is configured to acquire a single cell that meets a preset condition in the battery pack when the battery pack is in the second preset state, and use the single cell as a target single cell.

The first parameter determining module 160 is configured to extract cell state information of the target cell in a first preset state, as a first state parameter.

The second parameter determining module 170 is configured to acquire cell state information of the target cell in a second preset state, where the cell state information is used as a second state parameter.

The calculating module 180 is configured to calculate according to the first state parameter, the second state parameter, the preset nominal capacity, and the accumulated capacity data to obtain the SOH of the battery pack.

In an embodiment, in the apparatus, the information acquisition module 120 specifically includes a cell voltage obtaining unit, a cell SOC value determining unit, and a cell charge level determining unit.

The single cell voltage acquisition unit is used for acquiring the open-circuit voltage of each single cell.

The single cell SOC value determining unit is used for obtaining SOC values corresponding to open-circuit voltages of the single cells according to a preset OCV table and taking the SOC values as SOC correction values of the single cells in a first preset state.

The single battery cell charge level determining unit is used for determining the charge level of each single battery cell in a first preset state according to the SOC correction value.

In an embodiment, in the apparatus, the second parameter determining module 170 specifically includes a target cell voltage obtaining unit, a target cell SOC value determining unit, and a target cell charge level determining unit.

The target cell voltage acquisition unit is used for acquiring the open-circuit voltage of the target single cell.

The target cell SOC value determining unit is used for obtaining an SOC value corresponding to the open-circuit voltage of the target cell in the second preset state according to the preset OCV table, and the SOC value is used as an SOC correction value of the target cell in the second preset state.

The target cell charge level determining unit is used for determining the charge level of the target single cell in the second preset state according to the SOC correction value of the target single cell.

In one embodiment, in the apparatus, the calculation module 180 specifically includes a difference obtaining unit, a difference judging unit, and a confirmation calculating unit.

The difference value obtaining unit is used for obtaining a level difference value between the charge level of the target single battery cell in the second preset state and the charge level of the target single battery cell in the first preset state.

The difference value judging unit is used for judging whether the grade difference value exceeds a preset threshold value.

And the confirmation calculation unit is used for calculating according to the SOC correction value of the target single battery cell in the second preset state, the SOC correction value of the target single battery cell in the first preset state, the preset nominal capacitance and the accumulated capacitance data when the grade difference exceeds the preset threshold value, so as to obtain the SOH of the battery pack.

In an embodiment, before the information collecting module 120 is configured to collect the cell state information of each cell when the battery pack is in the first preset state, the apparatus further includes a condition determining module configured to determine whether the battery pack satisfies a preset OCV correction condition, and when the battery pack satisfies the preset OCV correction condition, the information collecting module 120 is turned to perform the collection of the cell state information of each cell when the battery pack is in the first preset state.

In an embodiment, after the capacitance obtaining module 130 is configured to obtain the accumulated capacitance data of the battery pack during the process from the first preset state to the second preset state, the cell determining module 150 is configured to obtain the individual cells that satisfy the preset condition in the battery pack when the battery pack is in the second preset state, before the individual cells are taken as the target individual cells, the apparatus further includes a condition detecting module configured to determine whether the preset correction condition is satisfied when the battery pack is in the second preset state, if so, the cell determining module 150 is switched to perform obtaining the individual cells that satisfy the preset condition in the battery pack when the battery pack is in the second preset state, and the individual cells are taken as the target individual cells.

For the specific limitations of the estimation device of the SOH of the battery pack, reference may be made to the limitations of the estimation method of the SOH of the battery pack, and the details are not repeated here. The modules in the estimation device of the SOH of the battery pack may be wholly or partially implemented by software, hardware and a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.

In one embodiment, there is provided a computer device comprising a memory and a processor, the memory storing a computer program, the processor implementing the following steps when executing the computer program: acquiring monomer state information of each monomer battery cell when the battery pack is in a first preset state; acquiring accumulated capacitance data of the battery pack in the process from a first preset state to a second preset state; extracting monomer state information of a target monomer battery cell in a first preset state to serve as a first state parameter; acquiring monomer state information of the target monomer battery cell in a second preset state as a second state parameter; and calculating according to the first state parameter, the second state parameter, the preset nominal capacitance and the accumulated capacitance data to obtain the SOH of the battery pack.

In one embodiment, the cell state information includes SOC correction values and charge levels; the processor, when executing the computer program, further performs the steps of: acquiring open-circuit voltage of each single battery cell; acquiring an SOC value corresponding to the open-circuit voltage of each single battery cell according to a preset OCV table, and taking the SOC value as an SOC correction value of each single battery cell in a first preset state; and determining the charge level of each single battery cell in a first preset state according to the SOC correction value.

In one embodiment, the processor, when executing the computer program, further performs the steps of: collecting the open-circuit voltage of a target single battery cell; acquiring an SOC value corresponding to the open-circuit voltage of the target single battery cell in a second preset state according to a preset OCV table, and taking the SOC value as an SOC correction value of the target single battery cell in the second preset state; and determining the charge level of the target single battery cell in a second preset state according to the SOC corrected value of the target single battery cell.

In one embodiment, the processor, when executing the computer program, further performs the steps of: acquiring a grade difference value between the charge grade of the target monomer battery cell in the second preset state and the charge grade of the target monomer battery cell in the first preset state; judging whether the grade difference value exceeds a preset threshold value or not; if so, calculating according to the SOC corrected value of the target single battery cell in the second preset state, the SOC corrected value of the target single battery cell in the first preset state, the preset nominal capacitance and the accumulated capacitance data to obtain the SOH of the battery pack.

In one embodiment, the processor, when executing the computer program, further performs the steps of: judging whether the battery pack meets a preset OCV correction condition or not; if so, the step of acquiring the monomer state information of each monomer electric core when the battery pack is in the first preset state is carried out.

In one embodiment, the processor, when executing the computer program, further performs the steps of: judging whether the battery pack meets a preset correction condition in a second preset state; if so, entering a step of acquiring the single electric core which meets the preset condition in the battery pack when the battery pack is in the second preset state, and taking the single electric core as a target single electric core.

In one embodiment, a computer-readable storage medium is provided, having a computer program stored thereon, which when executed by a processor, performs the steps of: acquiring monomer state information of each monomer battery cell when the battery pack is in a first preset state; acquiring accumulated capacitance data of the battery pack in the process from a first preset state to a second preset state; extracting monomer state information of a target monomer battery cell in a first preset state to serve as a first state parameter; acquiring monomer state information of the target monomer battery cell in a second preset state as a second state parameter; and calculating according to the first state parameter, the second state parameter, the preset nominal capacitance and the accumulated capacitance data to obtain the SOH of the battery pack.

In one embodiment, the cell state information includes SOC correction values and charge levels; the computer program when executed by the processor further realizes the steps of: acquiring open-circuit voltage of each single battery cell; acquiring an SOC value corresponding to the open-circuit voltage of each single battery cell according to a preset OCV table, and taking the SOC value as an SOC correction value of each single battery cell in a first preset state; and determining the charge level of each single battery cell in a first preset state according to the SOC correction value.

In one embodiment, the computer program when executed by the processor further performs the steps of: collecting the open-circuit voltage of a target single battery cell; acquiring an SOC value corresponding to the open-circuit voltage of the target single battery cell in a second preset state according to a preset OCV table, and taking the SOC value as an SOC correction value of the target single battery cell in the second preset state; and determining the charge level of the target single battery cell in a second preset state according to the SOC corrected value of the target single battery cell.

In one embodiment, the computer program when executed by the processor further performs the steps of: acquiring a grade difference value between the charge grade of the target monomer battery cell in the second preset state and the charge grade of the target monomer battery cell in the first preset state; judging whether the grade difference value exceeds a preset threshold value or not; if so, calculating according to the SOC corrected value of the target single battery cell in the second preset state, the SOC corrected value of the target single battery cell in the first preset state, the preset nominal capacitance and the accumulated capacitance data to obtain the SOH of the battery pack.

In one embodiment, the computer program when executed by the processor further performs the steps of: judging whether the battery pack meets a preset OCV correction condition or not; if so, the step of acquiring the monomer state information of each monomer electric core when the battery pack is in the first preset state is carried out.

In one embodiment, the computer program when executed by the processor further performs the steps of: judging whether the battery pack meets a preset correction condition in a second preset state; if so, entering a step of acquiring the single electric core which meets the preset condition in the battery pack when the battery pack is in the second preset state, and taking the single electric core as a target single electric core.

For a more complete explanation of the present application, a flow chart of a method for estimating SOH of a battery pack in a discharging mode is provided as shown in fig. 6.

In fig. 6, it is first necessary to determine whether the battery pack satisfies 0CV correction, where the OCV correction is an open-circuit voltage correction, and the OCV table is a relationship between an open-circuit voltage after the battery cell is left standing for 2h (calibration value) and a battery cell remaining capacity. If the OCV correction is satisfied, the subsequent steps can be performed, and if the OCV correction is not satisfied, the SOH calculation process is directly ended.

When the OCV correction is satisfied, the SOC0i of each cell can be calculated. The open-circuit voltage of each battery cell can be collected according to the BMS system, and then the SOC value of each battery cell is obtained by correcting the open-circuit voltage according to the OCV table, where SOC0i represents the SOC value of the ith battery cell, for example, the SOC value of the first battery cell is SOC 01.

Then, the State of charge State0i of each cell is obtained according to the SOC0 i. Defining the State of charge (State) of the battery cell as a low State of charge (SOC) when the SOC of the battery cell is less than or equal to 20%; when the SOC of the battery cell is more than or equal to 80%, the State of charge (State) of the battery cell is a high State of charge (SOC); when the SOC of the cell is between 20% and 80%, the State of charge State of the cell is a medium State of charge. For example, if the first cell SOC01 is 0.2, the State of charge State01 is a low State of charge.

Then, the discharge of the battery pack is started, and the accumulated discharge amount data Cdischg of the battery pack is obtained in the process.

And then, judging whether the battery pack meets an OCV correction condition or a full discharge correction condition, if so, performing subsequent steps, and if not, directly ending the SOH calculation process. The full discharge correction refers to directly correcting the SOC of the battery pack to 0% when the lowest single cell voltage reaches the lower cell voltage use limit during discharging.

Then, if the battery pack satisfies the full discharge correction condition, the SOC value (subsequently represented by socow 1) of the cell with the lowest voltage is 0%, and if the battery pack satisfies the OCV correction, a corresponding correction value is obtained as socow 1 through a preset OCV table according to the voltage of the cell with the lowest voltage.

Then, the state of charge Statelow1 of the voltage lowest cell is determined from the socow 1 of the voltage lowest cell, for example, the state of charge Statelow1 of the voltage lowest cell may be a low state of charge.

Then, the state of charge Statelow0 of the lowest voltage cell before discharge and the state of charge socow 0 of the lowest voltage cell before discharge are checked back.

And then, judging whether the state of charge before discharging of the single battery cell with the lowest voltage Statelow0 and the state of charge after discharging Statelow1 meet the condition that the state of charge jumps to the low state of charge, if so, performing subsequent steps, and if not, directly ending the SOH calculation process. In the whole discharging process, due to the problems of current sampling precision and the like, a certain calculation error exists in the accumulated discharging capacity Cdischg, and in order to reduce the influence of the accumulated discharging capacity Cdischg on the calculation of SOH, a state jump limit is added. The span of discharge from a high state of charge to a low state of charge may reduce the effect of the cumulative discharge amount Cdischg on the SOH calculation.

Finally, calculating the SOH of the battery pack according to a calculation formula,

where Cfresh is the fresh capacity, i.e., the nominal capacity of the battery when it is shipped from the factory.

As shown in fig. 7, a flow chart of a method for estimating SOH of a battery pack in a charging mode is provided.

In fig. 7, it is first necessary to determine whether the battery pack satisfies 0CV correction, where the OCV correction is an open-circuit voltage correction, and the OCV table is a relationship between an open-circuit voltage after the battery cell is left standing for 2h (calibration value) and a remaining battery cell capacity. If the OCV correction is satisfied, the subsequent steps can be performed, and if the OCV correction is not satisfied, the SOH calculation process is directly ended.

Then, the State of charge State0i of each cell is obtained according to the SOC0 i. Defining the State of charge (State) of the battery cell as a low State of charge (SOC) when the SOC of the battery cell is less than or equal to 20%; when the SOC of the battery cell is more than or equal to 80%, the State of charge (State) of the battery cell is a high State of charge (SOC); when the SOC of the cell is between 20% and 80%, the State of charge State of the cell is a medium State of charge. For example, if the first cell SOC01 is 0.8, the State of charge State01 is a high State of charge.

Then, the charging of the battery pack is started, and the accumulated charge amount data Cchg of the battery pack is obtained in this process.

And then, judging whether the battery pack meets the OCV correction condition or the full charge correction condition, if so, performing subsequent steps, and if not, directly ending the SOH calculation process. The full charge correction refers to directly correcting the SOC of the battery pack to be 100% when the highest single cell voltage reaches the upper limit of the cell voltage use during charging.

Then, if the battery pack satisfies the full charge correction condition, the SOC value (hereinafter, represented by socigh 1) of the highest-voltage cell is 100%, and if the battery pack satisfies the OCV correction, a corresponding correction value is obtained as socigh 1 through a preset OCV table according to the voltage of the highest-voltage cell.

Then, the state of charge Statehigh1 of the highest voltage cell is determined according to the socigh 1 of the highest voltage cell, for example, the state of charge Statehigh1 of the highest voltage cell may be a high state of charge.

And then, the state of charge Statehigh0 of the single cell with the highest voltage before charging and the state of charge socigh 0 before charging are checked back.

And then, judging whether the state of charge Statehigh0 before the charging of the single battery cell with the highest voltage and the state of charge Statehigh1 after the charging meet the low state of charge and jump to the high state of charge, if so, performing subsequent steps, and if not, directly ending the SOH calculation process. In the whole charging process, due to the problems of current sampling precision and the like, the accumulated charging capacity Cchg has a certain calculation error, and in order to reduce the influence of the accumulated charging capacity Cchg on the calculation of the SOH, a state jump limitation is added. The span of charging from a low state of charge to a high state of charge may reduce the effect of the accumulated charge Cchg on the SOH calculation.

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 more specific and detailed, but not construed as limiting the scope of the invention. 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, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A method of estimating SOH of a battery pack, the method comprising the steps of:

acquiring accumulated capacitance data of a battery pack in a process from a first preset state to a second preset state, wherein the first preset state is a state before the battery pack is discharged, the second preset state is a state after the battery pack is discharged, or the first preset state is a state before the battery pack is charged, and the second preset state is a state after the battery pack is charged;

acquiring a single battery cell which meets a preset condition in a battery pack when the battery pack is in a second preset state, and taking the single battery cell as a target single battery cell;

extracting monomer state information of the target monomer battery cell in a first preset state to serve as a first state parameter;

acquiring monomer state information of the target monomer battery cell in a second preset state, wherein the monomer state information is used as a second state parameter;

2. The method of claim 1, wherein the cell state information includes an SOC correction value.

3. The method of claim 1, wherein the cell state information includes an SOC correction value and a charge level; the method for acquiring the monomer state information of each monomer battery cell of the battery pack in the first preset state specifically comprises the following steps:

acquiring open-circuit voltage of each single battery cell;

acquiring SOC values corresponding to open-circuit voltages of the monomer battery cells according to a preset OCV table, wherein the SOC values are used as SOC correction values of the monomer battery cells in a first preset state;

4. The method according to claim 3, wherein the obtaining of the cell state information of the target cell in the second preset state as the second state parameter specifically includes:

collecting the open-circuit voltage of a target single battery cell;

acquiring an SOC value corresponding to the open-circuit voltage of the target single battery cell in a second preset state according to the preset OCV table, and taking the SOC value as an SOC correction value of the target single battery cell in the second preset state;

5. The method according to claim 4, wherein the calculating the SOH of the battery pack according to the first state parameter, the second state parameter and the accumulated capacity data comprises the following steps:

acquiring a level difference value between the charge level of the target monomer battery cell in a second preset state and the charge level of the target monomer battery cell in a first preset state;

if so, calculating according to the SOC correction value of the target single battery cell in the second preset state, the SOC correction value of the target single battery cell in the first preset state, a preset nominal capacitance and the accumulated capacitance data to obtain the SOH of the battery pack.

6. The method of claim 1, wherein before the collecting the cell state information of each cell in the battery pack in the first preset state, the method further comprises the following steps:

7. The method of claim 1, wherein after acquiring the accumulated capacitance data of the battery pack from the first preset state to the second preset state, acquiring the cell satisfying the preset condition in the second preset state, and before taking the cell as the target cell, the method further comprises:

8. An apparatus for estimating SOH of a battery pack, the apparatus comprising:

the battery cell determining module is used for acquiring a single battery cell which meets a preset condition in the battery pack when the battery pack is in a second preset state, and taking the single battery cell as a target single battery cell;

the first parameter determination module is used for extracting monomer state information of the target monomer battery cell in a first preset state to serve as a first state parameter;

the second parameter determination module is used for acquiring monomer state information of the target monomer battery cell in a second preset state, and the monomer state information is used as a second state parameter;

and the calculation module is used for calculating according to the first state parameter, the second state parameter, the preset nominal capacity and the accumulated capacity data to obtain the SOH of the battery pack.

9. A computer device comprising a memory and a processor, the memory storing a computer program, wherein the processor implements the steps of the method of any one of claims 1 to 7 when executing the computer program.

10. 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 of any one of claims 1 to 7.