CN118914891A

CN118914891A - Initial value calibration method and equipment for charge state of battery pack

Info

Publication number: CN118914891A
Application number: CN202411015813.8A
Authority: CN
Inventors: 杨庆伟; 康文蓉; 闫涛; 霍元
Original assignee: Huzhou Zhixin Power System Development Co ltd; Zhejiang Geely Holding Group Co Ltd; Zhejiang Geely Remote New Energy Commercial Vehicle Group Co Ltd
Current assignee: Huzhou Zhixin Power System Development Co ltd; Zhejiang Geely Holding Group Co Ltd; Zhejiang Geely Remote New Energy Commercial Vehicle Group Co Ltd
Priority date: 2024-07-26
Filing date: 2024-07-26
Publication date: 2024-11-08

Abstract

The application provides a method and equipment for calibrating an initial value of a charge state of a battery pack. The method comprises the following steps: when the vehicle standing time is longer than a first preset time length, acquiring a first mapping relation between a battery cell open circuit voltage during power-on, a battery cell temperature during power-on and a battery cell charge state corresponding to the battery cell temperature during power-on and the battery cell open circuit voltage; according to the first mapping relation, determining a first battery core charge state corresponding to the battery core open-circuit voltage during power-on; judging whether the charge state of the first battery cell is in a non-platform area of a first mapping relation; if so, correcting the stored value of the electric core state of charge by adopting the first electric core state of charge to obtain an initial value of the electric core state of charge, wherein the stored value of the electric core state of charge is the electric core state of charge stored in the last time of power-down. The method improves the accuracy of calibrating the initial value of the state of charge of the battery cell.

Description

Initial value calibration method and equipment for charge state of battery pack

Technical Field

The application relates to the technical field of batteries, in particular to a method and equipment for calibrating initial value of charge state of a battery pack.

Background

With the rapid development of the electric automobile industry, the power battery as a core component thereof has received a great deal of attention as to performance and management techniques. One of the key parameters in the Battery management system (Battery MANAGEMENT SYSTEM, BMS) is the State of Charge (SOC) of the Battery, which directly affects the endurance mileage and driving safety of the electric vehicle. Therefore, accurate estimation of the SOC of the battery is of great importance for improving the performance and safety of the electric vehicle.

Currently, the power battery SOC initial value estimation schemes commonly used in the industry depend mostly on the relationship between the open circuit voltage (Open Circuit Voltage, OCV) and the SOC of the battery. The SOC-OCV curves at different temperatures are fitted, the open-circuit voltage of the battery is measured after the battery is kept still, and then the corresponding SOC value is searched on the SOC-OCV curves to serve as an initial value. This method is based on the basic principle of electrochemical characteristics of the battery and can reflect the state of charge of the battery to some extent.

However, when the SOC initial value calibration is performed by adopting the SOC initial value estimation method based on the SOC-OCV curve, the SOC may be corrected toward the wrong direction, so that the SOC initial value is higher or lower, and further the endurance mileage and driving safety of the electric automobile are affected.

Disclosure of Invention

The application provides a method and equipment for calibrating an initial value of a charge state of a battery pack, which are used for solving the problem of inaccurate calibration of an initial value of an SOC in the prior art.

In a first aspect, the present application provides a method for calibrating an initial state of charge of a battery pack, including:

When the vehicle standing time is longer than a first preset time length, acquiring a first mapping relation between a battery cell open circuit voltage during power-on, a battery cell temperature during power-on and a battery cell charge state corresponding to the battery cell temperature during power-on and the battery cell open circuit voltage;

According to the first mapping relation, determining a first battery core charge state corresponding to the battery core open-circuit voltage during power-on;

Judging whether the charge state of the first battery cell is in a non-platform area of a first mapping relation;

If so, correcting the stored value of the electric core state of charge by adopting the first electric core state of charge to obtain an initial value of the electric core state of charge, wherein the stored value of the electric core state of charge is the electric core state of charge stored in the last time of power-down.

In some embodiments, determining whether the first cell state of charge is in a non-plateau region of the first mapping relationship comprises:

Calculating the slope of the first mapping relation at the first electric core charge state;

And when the slope is larger than a preset threshold, determining that the charge state of the first battery cell is in a non-platform area of the first mapping relation.

determining a second cell state of charge and a third cell state of charge according to the first mapping relation and the preset voltage deviation amount; the open-circuit voltage of the battery cell corresponding to the second battery cell charge state is the sum of the open-circuit voltage of the battery cell and the preset voltage deviation amount when the battery cell is powered on, and the open-circuit voltage of the battery cell corresponding to the third battery cell charge state is the difference between the open-circuit voltage of the battery cell and the preset voltage deviation amount when the battery cell is powered on;

Judging whether the difference between the second electric core charge state and the first electric core charge state and the difference between the first electric core charge state and the third electric core charge state are smaller than a first preset electric quantity deviation amount or not;

If yes, acquiring a second mapping relation and a third mapping relation according to the temperature of the battery cell and the preset temperature deviation amount during power-on; the battery cell temperature corresponding to the second mapping relation is the sum of the battery cell temperature and the preset temperature deviation amount when the battery is powered on; the temperature of the battery cell corresponding to the third mapping relation is the difference between the temperature of the battery cell when the battery cell is powered on and the preset temperature deviation amount;

and judging whether the charge state of the first battery cell is in a non-platform area of the first mapping relation according to the second mapping relation and the third mapping relation.

In some embodiments, determining whether the first battery cell state of charge is in the non-platform region of the first mapping relationship according to the second mapping relationship and the third mapping relationship includes:

according to the second mapping relation, determining a fourth battery cell charge state, wherein the battery cell open circuit voltage corresponding to the fourth battery cell charge state is the sum of the battery cell open circuit voltage and the preset voltage deviation amount when the battery cell is electrified;

According to the third mapping relation, determining a fifth battery cell charge state, wherein the battery cell open circuit voltage corresponding to the fifth battery cell charge state is the difference between the battery cell open circuit voltage and the preset voltage deviation amount when the battery cell open circuit voltage is electrified;

And when the difference between the fourth electric core charge state and the first electric core charge state and the difference between the first electric core charge state and the fifth electric core charge state are smaller than the second preset electric quantity deviation amount, determining that the first electric core charge state is in a non-platform area of the first mapping relation.

In some embodiments, correcting the stored state of charge value of the battery cell using the first state of charge of the battery cell to obtain an initial state of charge value of the battery cell includes:

determining a single correction amount according to an upper limit threshold and a lower limit threshold of the correction amount, wherein the upper limit threshold of the correction amount is the sum of a stored value of the charge state of the battery cell and a first correction amount limit value, and the lower limit threshold of the correction amount is the difference between the stored value of the charge state of the battery cell and the first correction amount limit value;

and according to the single correction quantity, adopting the first electric core charge state, and correcting the electric core charge state storage value step by step for multiple times to obtain an electric core charge state initial value.

In some embodiments, the lower correction threshold is a difference between the stored state of charge value of the battery cell and a second correction limit when the vehicle rest time is greater than a second predetermined time period, wherein the second predetermined time period is greater than the first predetermined time period and the second correction limit is greater than the first correction limit.

In some embodiments, obtaining the cell open circuit voltage at power up includes:

obtaining the maximum value and the minimum value of the measured open-circuit voltage of a plurality of battery cells in a battery pack;

and weighting and summing the maximum value of the actually measured open circuit voltage, the minimum value of the actually measured open circuit voltage and the upper and lower limit thresholds of the preset open circuit voltage to obtain the open circuit voltage of the battery cell during power-on.

In some embodiments, the method further comprises:

And if the first battery cell charge state is in the platform area of the first mapping relation, determining that the battery cell charge state storage value is the battery cell charge state initial value.

In some embodiments, the method further comprises:

And when the difference between the second electric core charge state and the first electric core charge state or the difference between the first electric core charge state and the third electric core charge state is larger than or equal to a first preset electric quantity deviation amount, determining the electric core charge state storage value as an electric core charge state initial value.

In some embodiments, the method further comprises:

And when the difference between the fourth electric core charge state and the first electric core charge state or the difference between the first electric core charge state and the fifth electric core charge state is larger than or equal to the second preset electric quantity deviation amount, determining the electric core charge state storage value as an electric core charge state initial value.

In a second aspect, the present application provides a device for calibrating an initial state of charge of a battery pack, comprising:

The acquisition module is used for acquiring the open-circuit voltage of the battery cell during power-on, the temperature of the battery cell during power-on and the first mapping relation between the charge state of the battery cell and the open-circuit voltage of the battery cell, which correspond to the temperature of the battery cell during power-on, when the standing time of the vehicle is longer than a first preset time length;

The determining module is used for determining a first battery core charge state corresponding to the battery core open-circuit voltage during power-on according to the first mapping relation;

The correction module is used for judging whether the charge state of the first battery cell is in a non-platform area of the first mapping relation;

In a third aspect, the present application provides an electronic device comprising: a memory and a processor;

The memory is used for storing a computer program; the processor is configured to execute a computer program stored in the memory, to implement the method for calibrating the initial value of the charge state of the battery pack in any embodiment of the first aspect and the first aspect.

In a fourth aspect, the present application provides a computer readable storage medium having stored therein a computer program which, when executed by a processor, implements the initial value calibration method of the battery pack state of charge in any one of the embodiments of the first aspect and the first aspect.

In a fifth aspect, the present application provides a computer program product comprising a computer program which, when executed by a processor, implements the initial calibration method of the state of charge of a battery pack of any one of the embodiments of the first aspect and the first aspect.

According to the battery pack state-of-charge initial value calibration method and the battery pack state-of-charge initial value calibration device, when the vehicle standing time is longer than the first preset time, the mapping relation between the open-circuit voltage of the battery cell and the state of charge of the battery cell at the time of power-on is obtained, the state of charge of the battery cell is determined according to the mapping relation, and the state of charge of the battery cell is located in the non-platform area of the mapping relation, the initial value of the state of charge of the battery cell is calibrated by adopting the state of charge of the battery cell, the problem that the state of charge of the battery cell is corrected inaccurately due to the fact that the platform area boundary of the mapping relation between the open-circuit voltage of the battery cell and the state of charge of the battery cell is preset inaccurately is solved, and the accuracy and the reliability of the state of charge calibration of the battery cell are improved.

Drawings

In order to more clearly illustrate the application or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the application, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

Fig. 1 is a flowchart of a method for calibrating initial state of charge of a battery pack according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a relationship between SOC and OCV according to an embodiment of the present application;

FIG. 3 is a schematic diagram of another SOC-OCV relationship in accordance with an embodiment of the present application;

FIG. 4 is a graph showing a trend of weighted voltage increasing with U _max according to an embodiment of the present application;

FIG. 5 is a graph showing a trend of weighted voltage decrease with U _min according to an embodiment of the present application;

fig. 6 is a schematic structural diagram of a calibration device for initial state of charge of a battery pack according to an embodiment of the present application;

fig. 7 is a schematic hardware structure of an electronic device according to an embodiment of the application.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

The terms first, second, third, fourth and the like in the description and in the claims and in the above drawings are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged where appropriate. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope herein.

Currently, a power battery SOC initial value estimation scheme commonly used in the industry depends on the relationship between OCV and SOC. The SOC-OCV curves at different temperatures are fitted, the open-circuit voltage of the battery is measured after the battery is kept still, and then the corresponding SOC value is searched on the SOC-OCV curves to serve as an initial value. This method is based on the basic principle of electrochemical characteristics of the battery and can reflect the state of charge of the battery to some extent.

In the calibration of the initial value of the SOC using the SOC-OCV curve lookup table, only the non-plateau region of the curve is usually allowed to be searched for to ensure accuracy. Although the initial value estimation method of the SOC based on the SOC-OCV curve has certain practicability, some problems still exist in practical application. Firstly, due to factors such as sampling point arrangement and sensor sampling errors, the measured battery cell temperature, voltage and the like are directly used as table lookup input, and the platform area of the SOC-OCV curve can be misjudged as a non-platform area, so that the accuracy of the initial value of the SOC is affected. Such misjudgment may cause the battery pack SOC to be corrected in the wrong direction, so that the initial value of the SOC is higher or lower, and further the endurance mileage and driving safety of the electric automobile are affected. Second, the definition of SOC-OCV curve plateau and non-plateau regions of lithium ion batteries is temperature sensitive, which requires that the effects of temperature factors must be considered in practical applications, adding to the complexity and cost of the system.

Aiming at the problems, the application provides a method and equipment for calibrating the initial value of the charge state of a battery pack. In the method, when the SOC-OCV curve is used for calibrating the initial value of the SOC, the calibration is only allowed to be carried out in a non-platform area of the SOC-OCV curve, and considering that the voltage ranges of the non-platform areas of the SOC-OCV curve at different temperatures are different, the SOC-OCV curves at different battery core temperatures are all judged whether the SOC is in the non-platform area, so that the calibration precision of the initial value of the SOC is improved.

The technical scheme of the application is described in detail below by specific examples. The following embodiments may be combined with each other, and some embodiments may not be repeated for the same or similar concepts or processes.

In the application, the electronic equipment is taken as an execution main body, and the initial value calibration method of the battery pack charge state of the following embodiment is executed. In particular, the execution body may be a hardware device of the electronic apparatus, or a software application implementing the embodiments described below in the electronic apparatus, or a computer-readable storage medium on which the software application implementing the embodiments described below is installed, or code of the software application implementing the embodiments described below.

Fig. 1 is a flowchart of a method for calibrating initial state of charge of a battery pack according to an embodiment of the application. As shown in fig. 1, with the electronic device as an execution body, the method of the present embodiment may include the following steps:

and S101, when the vehicle standing time is longer than a first preset time length, acquiring a first mapping relation between a battery core charge state and the battery core open circuit voltage, wherein the first mapping relation corresponds to the battery core open circuit voltage, the battery core temperature and the battery core temperature during power-on.

In this embodiment, the vehicle is kept stand for a first preset period of time, so that the polarization voltage is ensured to be stable, and at this time, the OCV and the cell temperature during power-up can be obtained. The mapping relationship between the battery cell SOC and the OCV is different at different battery cell temperatures, for example, the relationship between the battery cell SOC and the OCV is different at different battery cell temperatures as shown in fig. 2.

It should be understood that the electronic device may draw a battery cell SOC-OCV curve at different temperatures according to the battery cell OCV test data at different temperatures, and fit to obtain a functional relation between the battery cell SOC and the OCV, as shown in formula (1), and calculate to obtain a battery cell SOC value by taking the OCV and the temperature as inputs.

SOC ＝ f (OCV，T) (1)

The mapping relationship described in this embodiment may be a relationship curve or a relationship expression, which is not limited in this embodiment.

S102, determining a first battery core charge state corresponding to the battery core open circuit voltage during power-on according to the first mapping relation.

In this embodiment, the electronic device may calculate, according to the SOC-OCV relation corresponding to the temperature of the battery cell during power-up, an SOC, that is, the first battery cell state of charge.

The electronic device can also search the SOC corresponding to the OCV as the first battery charge state according to the SOC-OCV curve corresponding to the battery temperature during power-on.

S103, judging whether the charge state of the first battery cell is in a non-platform area of the first mapping relation.

In this embodiment, the non-plateau region is a portion of the SOC-OCV curve having a slope greater than a predetermined threshold. For the SOC-OCV relationship, a derivative above a predetermined threshold may be considered a non-plateau region.

And S104, if so, correcting the stored value of the charge state of the battery core by adopting the charge state of the first battery core to obtain an initial value of the charge state of the battery core.

The stored value of the charge state of the battery core is the charge state of the battery core stored in the last power-down process. And determining a non-platform region of the first battery core charge state in the first mapping relation, so that accuracy of SOC initial value calibration is ensured.

The method comprises the steps of correcting the stored value of the electric core state of charge by adopting the first electric core state of charge, wherein the stored value of the electric core state of charge is specifically adjusted to be within a preset range with the difference value of the stored value of the electric core state of charge and the first electric core state of charge, and at the moment, the corrected stored value of the electric core state of charge is the initial value of the electric core state of charge.

According to the battery pack state of charge initial value calibration method, when the state of charge of the first battery core is determined to be in the non-platform region of the SOC-OCV mapping relation, the state of charge storage value of the first battery core is adopted to calibrate the state of charge of the battery core, so that the accuracy of SOC initial value calibration is improved, the method is simple in implementation process and low in cost. Compared with the prior art, the method of the embodiment does not need to preset the voltage interval range of the non-platform area, but automatically matches according to the temperature and the voltage slope to judge whether the current battery cell SOC is in the non-platform area, thereby effectively solving the problem of error correction of the SOC caused by inaccurate preset of the boundary of the non-platform area of the SOC-OCV curve.

Optionally, the specific implementation manner of step S103 includes:

S201, calculating the slope of the first mapping relation at the first electric core charge state.

And S202, when the slope is larger than a preset threshold, determining that the charge state of the first battery cell is in a non-platform area of the first mapping relation.

For example, deriving the formula (1), substituting the battery cell temperature and the OCV at the time of power-up, and obtaining the slope of the first mapping relationship at the first battery cell state of charge. The slope is larger than a preset threshold, so that the change of the OCV along with the SOC is obvious, and the charge state of the first battery cell is in a non-platform area of the first mapping relation.

In some embodiments, the specific implementation of step S103 includes:

S301, determining a second electric core charge state and a third electric core charge state according to the first mapping relation and the preset voltage deviation amount.

The preset voltage deviation amount can be determined according to the cell characteristics. The open-circuit voltage of the battery cell corresponding to the second battery cell charge state is the sum of the open-circuit voltage of the battery cell and the preset voltage deviation amount when the battery cell is powered on, and the open-circuit voltage of the battery cell corresponding to the third battery cell charge state is the difference between the open-circuit voltage of the battery cell and the preset voltage deviation amount when the battery cell is powered on.

The first mapping relation is an SOC-OCV mapping relation corresponding to the battery cell temperature during power-on, and therefore the battery cell temperature corresponding to the second battery cell state of charge and the battery cell temperature corresponding to the third battery cell state of charge are both battery cell temperatures during power-on.

As shown in fig. 3, when the first mapping relationship is an SOC-OCV curve, the first battery cell state of charge, the second battery cell state of charge, and the third battery cell state of charge are respectively at points a, B, and C on the SOC-OCV curve.

It should be appreciated that SOC _A＝f(U,T),SOC_B＝f(U+ΔU,T),SOC_C = f (U- Δu, T).

S302, judging whether the difference between the second electric core charge state and the first electric core charge state and the difference between the first electric core charge state and the third electric core charge state are smaller than a first preset electric quantity deviation amount or not.

Specifically, when both Δsoc ₁＝SOC_B－SOC_A,ΔSOC₂＝SOC_A－SOC_C,ΔSOC₁ and Δsoc ₂ are smaller than the first preset electric quantity deviation amount, it indicates that the OCV acquisition of the battery cell during power-up is more accurate, and the method can be used for determining the SOC. If Δsoc ₁ or Δsoc ₂ is greater than or equal to the first preset amount of deviation, it may be considered that the first battery core state of charge is in the platform region of the first mapping relationship, and may not be used for SOC initial value calibration.

And S303, if so, acquiring a second mapping relation and a third mapping relation according to the temperature of the battery cell and the preset temperature deviation amount during power-on.

The preset temperature deviation amount can be determined according to the sampling precision of the sensor and the temperature distribution difference of the battery cell body. The battery cell temperature corresponding to the second mapping relation is the sum of the battery cell temperature and the preset temperature deviation amount when the battery is powered on; the temperature of the battery cell corresponding to the third mapping relation is the difference between the temperature of the battery cell when the battery cell is powered on and the preset temperature deviation amount. The SOC-OCV curve corresponding to the second mapping relationship and the third mapping relationship is shown in fig. 3.

S304, judging whether the first electric core charge state is in a non-platform area of the first mapping relation according to the second mapping relation and the third mapping relation.

Specifically, the slopes of the second mapping relation and the third mapping relation at the first electric core charge state can be calculated, and when the slopes are both larger than a preset threshold value, the first electric core charge state can be indicated to be in the non-platform area of the first mapping relation.

Optionally, the specific implementation manner of step S304 may include:

s3041, determining the charge state of the fourth battery core according to the second mapping relation.

The open-circuit voltage of the battery cell corresponding to the charge state of the fourth battery cell is the sum of the open-circuit voltage of the battery cell and the preset voltage deviation amount when the battery cell is electrified.

S3042, determining the charge state of the fifth battery core according to the third mapping relation.

The open-circuit voltage of the battery cell corresponding to the charge state of the fifth battery cell is the difference between the open-circuit voltage of the battery cell and the preset voltage deviation amount when the battery cell is electrified.

With continued reference to fig. 3, the fourth and fifth cell states of charge are points D and E, respectively, on the SOC-OCV curve.

It should be appreciated that SOC _D＝f(U+ΔU,T+ΔT),SOC_E = f (U- Δu, T- Δt).

S3043, determining that the first electric core charge state is in a non-platform area of the first mapping relation when the difference between the fourth electric core charge state and the first electric core charge state and the difference between the first electric core charge state and the fifth electric core charge state are smaller than the second preset electric quantity deviation amount.

Specifically, when both Δsoc ₃＝SOC_D－SOC_A,ΔSOC₄＝SOC_A－SOC_E,ΔSOC₃ and Δsoc ₄ are smaller than the second preset electric quantity deviation amount, it indicates that the battery core temperature acquisition during power-up is more accurate, and the method can be used for determining the SOC.

According to the battery pack state of charge initial value calibration method, the judgment strategy of the first battery core state of charge in the non-platform area of the first mapping relation is optimized, the battery core temperature and OCV acquisition during power-on are determined accurately according to the preset voltage deviation amount and the preset temperature deviation amount, the influence of sampling deviation on the SOC initial value estimation precision is reduced, the probability of SOC error correction is reduced, the reliability of SOC calibration is improved, and the SOC initial value precision is improved.

In some embodiments, in step S104, correcting the stored value of the state of charge of the battery cell with the first state of charge of the battery cell to obtain an initial value of the state of charge of the battery cell includes:

S1041, determining a single correction amount according to the correction amount upper and lower limit thresholds.

The upper limit correction threshold is the sum of the stored value of the charge state of the battery cell and the first correction limit value, and the lower limit correction threshold is the difference between the stored value of the charge state of the battery cell and the first correction limit value.

S1042, according to the single correction, adopting the first electric core state of charge, and correcting the electric core state of charge storage value step by step for multiple times to obtain the electric core state of charge initial value.

In this embodiment, in order to avoid the problem of excessive error after SOC correction due to factors such as OCV of the battery cell, untimely uploading of temperature samples of the battery cell, etc., the stored value of the state of charge of the battery cell may be corrected step by step multiple times according to the preset upper and lower limit thresholds of the SOC correction amount until the difference between the stored value of the state of charge of the battery cell and the state of charge of the first battery cell is smaller than the preset threshold.

The SOC after each correction is shown in formula (2):

The SOC is an initial value of the calibrated SOC;

f (U, T) is the first cell state of charge;

SOC _NVM is a stored value of the state of charge of the battery cell;

ΔSOC _lim1 is a first modifier limit, which is greater than 0.

Optionally, when the vehicle standing time is longer than a second preset time period, the correction lower limit threshold is a difference between the stored value of the charge state of the battery core and a second correction limit value, wherein the second preset time period is longer than the first preset time period, and the second correction limit value is longer than the first correction limit value.

Specifically, when the vehicle rest time is longer than the second preset period, the SOC correction amount lower limit threshold value may be reduced in consideration of the influence of factors such as self-discharge.

The SOC after each correction is shown in formula (3):

Wherein Δsoc _lim2>ΔSOC_lim1.

In this embodiment, a step-by-step multiple correction mode is adopted to correct the stored value of the charge state of the battery core, so that the problem of overlarge error after the correction of the SOC is avoided, and the accuracy of the correction of the initial value of the SOC is further improved.

In some embodiments, the obtaining the open cell voltage at power up in step S101 includes:

S1011, obtaining the maximum value and the minimum value of the actually measured open-circuit voltage of a plurality of battery cells in the battery pack.

And S1012, weighting and summing the maximum value of the actually measured open circuit voltage, the minimum value of the actually measured open circuit voltage and the upper and lower limit thresholds of the preset open circuit voltage to obtain the open circuit voltage of the battery cell during power-on.

In this embodiment, upper and lower limit thresholds of the OCV voltage of the battery cell at different temperatures may be preset according to the performance parameters of the battery cell, where the SOCs corresponding to the upper and lower limit thresholds of the OCV voltage of the battery cell are 100% and 0% respectively. Table 1 is an example of upper and lower cell OCV thresholds.

TABLE 1 cell OCV upper and lower threshold examples

Temperature (temperature)	-30℃	-20℃	-10℃	0℃	10℃	25℃	45℃	55℃
									Upper limit of OCV	3.360	3.362	3.355	3.355	3.346	3.341	3.339	3.339
OCV lower limit	2.827	2.824	2.823	2.812	2.691	2.624	2.621	2.616

Calculating the open-circuit voltage of the battery cell when power is supplied according to the formula (4):

wherein U _{Weighting of} is the open circuit voltage of the battery cell when power is on;

U _limlow is the lower threshold of the OCV of the battery cell;

u _limup is the upper threshold of the OCV of the battery cell;

U _min is the minimum measured OCV for the monomer, U _{Weighting of}＝U_min when U _min≤U_limlow;

u _max is the maximum measured OCV for the monomer, U _{Weighting of}＝U_max when U _max≥U_limup.

In one embodiment, assuming U _min remains unchanged (assuming 3.1V), at 25℃with U _max as an argument, equation (4) is modified to equation (5), and the curve of U _{Weighting of} is shown in FIG. 4.

As shown in fig. 4, when U _min＝3.1V、U_max =3.1v, the weighted voltage U _{Weighting of} is calculated to be 3.1V, but as U _max gradually increases to U _limup, the weight of U _max in U _{Weighting of} increases, and U _{Weighting of} is closer to U _max.

Under the condition that U _max is close to U _limup, when in discharge, U _min is far away from discharge cut-off voltage, U _min can not reach the discharge cut-off voltage in a short time, and after a period of time, SOC is dynamically corrected, and the over-discharge risk is small; and when the charging is performed, the distance between the U _max and the charging cut-off voltage is relatively close, the U _max can quickly approach the charging cut-off voltage, if the average voltage is used for table lookup, the SOC calculation is relatively low, the SOC is difficult to be corrected into an accurate value by dynamic SOC correction in a short time, the overcharge risk is easy to occur, and if the table lookup is used for U _{Weighting of}, the initial value of the SOC is relatively accurate without dynamic SOC correction for a long time, so that the overcharge risk can be effectively avoided.

In another embodiment, assuming U _max remains unchanged (assuming 3.1V), at 25℃with U _min as an argument, equation (4) is modified to equation (6), and the curve of U _{Weighting of} is shown in FIG. 5.

As shown in fig. 5, when U _min＝3.1V、U_max =3.1v, the weighted voltage U _{Weighting of} is calculated to be 3.1V, but as U _min gradually decreases to U _limlow, the weight of U _min in U _{Weighting of} gradually increases, and U _{Weighting of} is closer to U _min.

Under the condition that U _min is close to U _limlow, when in charging, U _max is far away from the charging cut-off voltage, U _max can not reach the charging cut-off voltage in a short time, and after a period of time, SOC is dynamically corrected, so that the risk of overcharging is small; and when discharging, U _min is closer to the discharge cut-off voltage, if the average voltage is used for looking up a table, the SOC calculation is higher, U _min can be rapidly close to the discharge cut-off voltage, the SOC is difficult to be corrected to an accurate value by dynamic correction in a short time, the risk of over-discharge is easy to occur, and if the table is used for looking up U _{Weighting of}, the initial value of the SOC is also more accurate without dynamic correction of the long-time SOC, and the risk of over-discharge can be effectively avoided.

In this embodiment, the OCV value of the battery cell used for table lookup based on the OCV extremum weighting is adaptively adjusted along with the state of the battery voltage extremum, so that the influence of the maximum and minimum single voltage on the state of charge of the first battery cell is considered, and when the consistency of the battery cells in the battery pack is poor, the risk of overcharge or overdischarge of the battery can be reduced, the rationality of the state of charge of the first battery cell is increased, and the correction accuracy of the initial value of the SOC is further improved.

In some embodiments, if the first battery state of charge is in the plateau region of the first mapping relationship, the battery state of charge storage value is determined to be the battery state of charge initial value.

In some embodiments, the stored state of charge value of the electrical core is determined to be the initial state of charge value of the electrical core when the difference between the second state of charge of the electrical core and the first state of charge of the electrical core or the difference between the first state of charge of the electrical core and the third state of charge of the electrical core is greater than or equal to a first predetermined amount of electrical charge deviation.

The difference between the second electric core charge state and the first electric core charge state or the difference between the first electric core charge state and the third electric core charge state is greater than or equal to a first preset electric quantity deviation amount, which can indicate that the first electric core charge state is in a platform area of a first mapping relation.

In some embodiments, the stored state of charge value of the electrical core is determined to be the initial state of charge value of the electrical core when the difference between the fourth state of charge of the electrical core and the first state of charge of the electrical core or the difference between the first state of charge of the electrical core and the fifth state of charge of the electrical core is greater than or equal to a second predetermined amount of electrical charge deviation.

The difference between the fourth electric core charge state and the first electric core charge state or the difference between the first electric core charge state and the fifth electric core charge state is greater than or equal to the second preset electric quantity deviation amount, which can indicate that the first electric core charge state is in the platform area of the first mapping relation.

In the above embodiment, the platform area where the first electric core charge state is in the first mapping relationship may not be used for correcting the electric core charge state storage value, and the electric core charge state storage value may be directly used as the electric core charge state initial value.

Fig. 6 is a schematic structural diagram of a calibration device for initial state of charge of a battery pack according to an embodiment of the application. As shown in fig. 6, the initial battery pack state of charge calibration apparatus 10 of the present embodiment is configured to implement the operations corresponding to the electronic device in any of the above method embodiments, and the initial battery pack state of charge calibration apparatus 10 of the present embodiment includes:

the obtaining module 11 is configured to obtain a first mapping relationship between a battery cell charge state and a battery cell open circuit voltage, where the battery cell open circuit voltage is greater than a first preset duration, the battery cell temperature is greater than the battery cell temperature, and the battery cell charge state corresponds to the battery cell temperature;

the determining module 12 is configured to determine, according to the first mapping relationship, a first electrical core charge state corresponding to an electrical core open circuit voltage during power-up;

The correction module 13 is configured to determine whether the first electrical core charge state is in a non-platform area of the first mapping relationship;

The initial value calibration device 10 for battery pack state of charge provided in the embodiment of the present application may execute the above method embodiment, and the specific implementation principle and technical effects of the method embodiment may be referred to the above method embodiment, and this embodiment is not repeated herein.

Fig. 7 shows a schematic hardware structure of an electronic device according to an embodiment of the present application. As shown in fig. 7, the electronic device 20, configured to implement operations corresponding to the electronic device in any of the above method embodiments, the electronic device 20 of this embodiment may include: a memory 21, a processor 22 and a communication interface 24.

A memory 21 for storing a computer program. The Memory 21 may include a high-speed random access Memory (Random Access Memory, RAM), and may further include a Non-Volatile Memory (NVM), such as at least one magnetic disk Memory, and may also be a U-disk, a removable hard disk, a read-only Memory, a magnetic disk, or an optical disk.

A processor 22 for executing a computer program stored in a memory to implement the method in the above-described embodiments. Reference may be made in particular to the relevant description of the embodiments of the method described above. The Processor 22 may be a central processing unit (Central Processing Unit, CPU), or may be other general purpose Processor, digital signal Processor (DIGITAL SIGNAL Processor, DSP), application SPECIFIC INTEGRATED Circuit (ASIC), or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of a method disclosed in connection with the present invention may be embodied directly in a hardware processor for execution, or in a combination of hardware and software modules in a processor for execution.

Alternatively, the memory 21 may be separate or integrated with the processor 22.

When memory 21 is a separate device from processor 22, electronic device 20 may also include bus 23. The bus 23 is used to connect the memory 21 and the processor 22. The bus 23 may be an industry standard architecture (Industry Standard Architecture, ISA) bus, an external device interconnect (PERIPHERAL COMPONENT INTERCONNECT, PCI) bus, or an extended industry standard architecture (Extended Industry Standard Architecture, EISA) bus, among others. The buses may be divided into address buses, data buses, control buses, etc. For ease of illustration, the buses in the drawings of the present application are not limited to only one bus or to one type of bus.

The communication interface 24 may be connected to the processor 22 via a bus 23. The processor 22 may control the communication interface 24 to perform the functions of receiving and transmitting signals.

The electronic device 20 provided in this embodiment may be used to execute the above-mentioned calibration method for initial value of battery pack state of charge, and its implementation manner and technical effects are similar, and this embodiment will not be repeated here.

The present application also provides a computer readable storage medium having stored therein a computer program/instruction which when executed by a processor is adapted to carry out the methods provided by the various embodiments described above.

The computer readable storage medium may be a computer storage medium or a communication medium. Communication media includes any medium that facilitates transfer of a computer program from one place to another. Computer storage media can be any available media that can be accessed by a general purpose or special purpose computer. For example, a computer-readable storage medium is coupled to the processor such that the processor can read information from, and write information to, the computer-readable storage medium. In the alternative, the computer-readable storage medium may be integral to the processor. The processor and the computer readable storage medium may reside in an Application SPECIFIC INTEGRATED Circuits (ASIC). In addition, the ASIC may reside in a user device. The processor and the computer-readable storage medium may also reside as discrete components in a communication device.

In particular, the computer readable storage medium may be implemented by any type or combination of volatile or non-volatile Memory devices, such as Static Random-Access Memory (SRAM), electrically erasable programmable Read-Only Memory (EEPROM), erasable programmable Read-Only Memory (Erasable Programmable Read Only Memory, EPROM), programmable Read-Only Memory (Programmable Read-Only Memory, PROM), read-Only Memory (ROM), magnetic Memory, flash Memory, magnetic or optical disk. A storage media may be any available media that can be accessed by a general purpose or special purpose computer.

The present application also provides a computer program product comprising a computer program/instructions stored in a computer readable storage medium. At least one processor of the device may read the computer program/instructions from a computer-readable storage medium, execution of the computer program/instructions by at least one processor causing the device to perform the methods provided by the various embodiments described above.

In the several embodiments provided by the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of modules is merely a logical function division, and there may be additional divisions of actual implementation, e.g., multiple modules may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or modules, which may be in electrical, mechanical, or other forms.

Wherein the individual modules may be physically separated, e.g. mounted in different locations of one device, or mounted on different devices, or distributed over a plurality of network elements, or distributed over a plurality of processors. The modules may also be integrated together, e.g. mounted in the same device, or integrated in a set of codes. The modules may exist in hardware, or may also exist in software, or may also be implemented in software plus hardware. The application can select part or all of the modules according to actual needs to realize the purpose of the scheme of the embodiment.

It should be understood that, although the steps in the flowcharts in the above embodiments are sequentially shown as indicated by arrows, these steps are not necessarily sequentially performed in the order indicated by the arrows. The steps are not strictly limited in order and may be performed in other orders, unless explicitly stated herein. Moreover, at least some of the steps in the figures may include multiple sub-steps or stages that are not necessarily performed at the same time, but may be performed at different times, the order of their execution not necessarily occurring in sequence, but may be performed alternately or alternately with other steps or at least a portion of the other steps or stages.

It should be noted that, the user information (including but not limited to user equipment information, user personal information, etc.) and the data (including but not limited to data for analysis, stored data, presented data, etc.) related to the present application are information and data authorized by the user or fully authorized by each party, and the collection, use and processing of the related data need to comply with the related laws and regulations and standards of the related country and region, and provide corresponding operation entries for the user to select authorization or rejection.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same. Although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments may be modified or some or all of the technical features may be replaced with equivalents. Such modifications and substitutions do not depart from the spirit of the application.

Claims

1. A method for calibrating an initial state of charge of a battery pack, the method comprising:

When the vehicle standing time is longer than a first preset time length, acquiring a battery cell open circuit voltage during power-on, a battery cell temperature during power-on and a first mapping relation between a battery cell charge state and the battery cell open circuit voltage, wherein the battery cell charge state corresponds to the battery cell temperature during power-on;

determining a first battery core charge state corresponding to the battery core open-circuit voltage during power-on according to the first mapping relation;

Judging whether the first cell charge state is in a non-platform area of the first mapping relation;

And if so, correcting the stored value of the electric core charge state by adopting the first electric core charge state to obtain an initial value of the electric core charge state, wherein the stored value of the electric core charge state is the electric core charge state stored in the last power-down process.

2. The method of claim 1, wherein determining whether the first battery state of charge is in a non-plateau region of the first mapping relationship comprises:

And when the slope is larger than a preset threshold, determining that the first battery core charge state is in a non-platform area of the first mapping relation.

3. The method of claim 1, wherein determining whether the first battery state of charge is in a non-plateau region of the first mapping relationship comprises:

Determining a second cell state of charge and a third cell state of charge according to the first mapping relation and a preset voltage deviation value; the open-circuit voltage of the battery cell corresponding to the second battery cell charge state is the sum of the open-circuit voltage of the battery cell and the preset voltage deviation amount when the battery cell is powered on, and the open-circuit voltage of the battery cell corresponding to the third battery cell charge state is the difference between the open-circuit voltage of the battery cell and the preset voltage deviation amount when the battery cell is powered on;

If yes, acquiring a second mapping relation and a third mapping relation according to the temperature of the battery cell during power-on and a preset temperature deviation value; the battery cell temperature corresponding to the second mapping relation is the sum of the battery cell temperature and the preset temperature deviation amount during power-up; the battery cell temperature corresponding to the third mapping relation is the difference between the battery cell temperature during power-up and the preset temperature deviation amount;

and judging whether the first electric core charge state is in a non-platform area of the first mapping relation according to the second mapping relation and the third mapping relation.

4. The method of claim 3, wherein determining whether the first cell state of charge is in a non-plateau region of the first mapping relationship according to the second mapping relationship and the third mapping relationship comprises:

determining a fourth battery cell charge state according to the second mapping relation, wherein the battery cell open-circuit voltage corresponding to the fourth battery cell charge state is the sum of the battery cell open-circuit voltage and the preset voltage deviation amount during power-up;

Determining a fifth battery cell charge state according to the third mapping relation, wherein the battery cell open-circuit voltage corresponding to the fifth battery cell charge state is the difference between the battery cell open-circuit voltage and the preset voltage deviation amount during power-up;

And when the difference between the fourth electric core charge state and the first electric core charge state and the difference between the first electric core charge state and the fifth electric core charge state are smaller than a second preset electric quantity deviation amount, determining that the first electric core charge state is in a non-platform area of the first mapping relation.

5. The method of claim 1, wherein correcting the stored state of charge value of the battery cell using the first state of charge of the battery cell to obtain an initial state of charge value of the battery cell comprises:

Determining a single correction amount according to a correction amount upper limit threshold, wherein the correction amount upper limit threshold is the sum of the battery cell charge state storage value and a first correction amount limit value, and the correction amount lower limit threshold is the difference between the battery cell charge state storage value and the first correction amount limit value;

and correcting the stored value of the charge state of the battery core step by step for multiple times by adopting the charge state of the first battery core according to the single correction amount to obtain an initial value of the charge state of the battery core.

6. The method of claim 5, wherein the lower correction threshold is a difference between the stored state of charge value of the battery cell and a second correction limit when the vehicle rest time is greater than a second predetermined time period, wherein the second predetermined time period is greater than the first predetermined time period and the second correction limit is greater than the first correction limit.

7. The method of claim 1, wherein the obtaining the cell open circuit voltage at power up comprises:

obtaining the maximum value and the minimum value of the measured open-circuit voltage of a plurality of battery cells in the battery pack;

And carrying out weighted summation on the maximum value of the actually measured open circuit voltage, the minimum value of the actually measured open circuit voltage and the upper and lower limit thresholds of the preset open circuit voltage to obtain the open circuit voltage of the battery cell during power-on.

8. The method according to claim 1, wherein the method further comprises:

and if the first electric core charge state is in the platform area of the first mapping relation, determining the electric core charge state storage value as an electric core charge state initial value.

9. A method according to claim 3, characterized in that the method further comprises:

And when the difference between the second electric core charge state and the first electric core charge state or the difference between the first electric core charge state and the third electric core charge state is larger than or equal to the first preset electric quantity deviation amount, determining that the electric core charge state storage value is an electric core charge state initial value.

10. The method according to claim 4, wherein the method further comprises:

and when the difference between the fourth electric core charge state and the first electric core charge state or the difference between the first electric core charge state and the fifth electric core charge state is larger than or equal to the second preset electric quantity deviation amount, determining that the electric core charge state storage value is an electric core charge state initial value.

11. A battery pack state of charge initial calibration device, the device comprising:

the determining module is used for determining a first battery core charge state corresponding to the battery core open circuit voltage during power-on according to the first mapping relation;

The correction module is used for judging whether the first electric core charge state is in a non-platform area of the first mapping relation;

12. An electronic device, the device comprising: a memory and a processor;

The memory is used for storing a computer program;

The processor is configured to execute the computer program stored in the memory, and implement the method for calibrating the initial value of the charge state of the battery pack according to any one of claims 1 to 10.

13. A computer readable storage medium, characterized in that the computer readable storage medium has stored therein a computer program which, when executed by a processor, is adapted to carry out the battery pack state of charge initial value calibration method according to any one of claims 1-10.

14. A computer program product, characterized in that the computer program product comprises a computer program which, when executed by a processor, implements the battery pack state of charge initial value calibration method of any one of claims 1-10.