WO2017139967A1

WO2017139967A1 - Battery pack balancing method, battery management system and battery system

Info

Publication number: WO2017139967A1
Application number: PCT/CN2016/074116
Authority: WO
Inventors: 陈玲; 杨元金; 周伟; 邓兆轩; 蔡毅; 种晋
Original assignee: 宁德时代新能源科技股份有限公司
Priority date: 2016-02-19
Filing date: 2016-02-19
Publication date: 2017-08-24
Also published as: CN108780927A; CN108780927B

Abstract

A battery pack balancing method, a battery management system and a battery system. Said balancing method comprises: detecting the voltage data of each battery cell in a lithium iron phosphate battery pack and acquiring, according to the voltage data of each battery cell, the state of charge of the lithium iron phosphate battery pack (S101), and acquiring a minimum voltage value from the voltage data (S102); accordingly, determining whether the state of charge ranges from 10% to 40%, and respectively comparing the difference between the voltage data of each battery cell in the lithium iron phosphate battery pack and the minimum voltage value with a preset voltage threshold (S103); and if it is determined that the state of charge ranges from 10% to 40% and there is a battery cell in which the difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold, discharging the battery cell (S104). Said balancing method improves the consistency of the state of charge among the battery cells in the lithium iron phosphate battery pack, extending the service life of the lithium iron phosphate battery pack.

Description

Battery pack equalization method, battery management system, and battery system

[Technical Field]

The present invention relates to the field of battery technologies, and in particular, to a battery pack equalization method, a battery management system, and a battery system.

【Background technique】

LiFePO ₄ Battery Pack has a typical charging and discharging platform. This excellent electrical performance, high cycle life and high safety make this product widely used in electric vehicles and energy storage.

The lithium iron phosphate battery system consists of a lithium iron phosphate battery pack and a battery management system. The lithium iron phosphate battery pack consists of a large number of battery cells connected in series or in parallel or mixed. The battery unit is not identical due to variations in raw materials and manufacturing processes, so the state of charge (SoC) between the cells is not the same. As a result, during the use of the lithium iron phosphate battery system, after repeated charging, discharging and calendar storage, the imbalance of the charge between the battery cells gradually increases, directly affecting the power capability and available energy of the lithium iron phosphate battery system. The play reduces the service life of the lithium iron phosphate battery pack.

[Summary of the Invention]

In view of this, the present invention provides a battery pack equalization method, a battery management system, and a battery system, which improves the consistency of the state of charge between the battery cells in the lithium iron phosphate battery pack, and prolongs the use of the lithium iron phosphate battery pack. life.

An aspect of an embodiment of the present invention provides a battery pack equalization method, including:

Detecting voltage data of each battery cell in the lithium iron phosphate battery pack, and acquiring a state of charge of the lithium iron phosphate battery pack according to voltage data of each battery unit;

Obtaining a minimum voltage value in the voltage data;

Determining whether the state of charge is between 10% and 40%, and comparing the difference between the voltage data of each battery cell in the lithium iron phosphate battery pack and the minimum voltage value and a preset voltage threshold ;

If it is determined that the state of charge is between 10% and 40%, and there is a battery unit whose difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold, in the lithium iron phosphate battery pack A battery unit having a difference between the voltage data and the minimum voltage value greater than or equal to the voltage threshold performs discharge.

The aspect as described above and any possible implementation manner further provide an implementation manner, where the method further includes:

Stopping, when the voltage data of the discharged battery cells in the iron phosphate battery pack reaches a specified condition, a difference between a voltage data in the iron phosphate battery pack and the minimum voltage value is greater than or equal to the voltage The discharge of the battery cells of the threshold.

In an aspect as described above and any possible implementation, an implementation is further provided, the specified condition comprising: voltage data of the discharged battery cells in the iron phosphate battery pack being consistent with the minimum voltage value.

The aspect and any possible implementation manners described above further provide an implementation manner for detecting voltage data of each battery unit in the lithium iron phosphate battery pack, including:

In the sleep mode, detecting voltage data of each battery cell in the lithium iron phosphate battery pack;

The sleep mode includes the lithium iron phosphate battery pack having no input energy or output energy.

In an aspect as described above and any possible implementation, an implementation is further provided, each battery unit comprising one battery cell, or each battery cell comprising at least two battery cells in parallel.

The aspect as described above and any possible implementation manner further provide an implementation manner, wherein each battery cell in the lithium iron phosphate battery pack comprises lithium iron phosphate having a solid content of greater than or equal to 90% in the cathode active material. Lithium ion battery cell.

An aspect of an embodiment of the present invention provides a battery management system, including:

a detecting module for detecting voltage data of each battery unit in the lithium iron phosphate battery pack;

a power estimation module, configured to obtain the lithium iron phosphate battery according to voltage data of each battery unit The state of charge of the package;

An equalization module, configured to obtain a minimum voltage value in the voltage data; and, determining whether the state of charge is located at 10% to 40%, and respectively comparing voltage data of each battery unit in the lithium iron phosphate battery pack Comparing the difference between the minimum voltage values with a preset voltage threshold; and, if it is determined that the state of charge is between 10% and 40%, and there is a difference between the voltage data and the minimum voltage value The battery unit having a value greater than or equal to the voltage threshold performs discharging on a battery unit in which a difference between voltage data and the minimum voltage value in the lithium iron phosphate battery pack is greater than or equal to the voltage threshold.

The above-mentioned aspect and any possible implementation manner further provide an implementation manner, where the equalization module is further configured to:

The foregoing aspect and any possible implementation manner further provide an implementation manner, where the detecting module is specifically configured to: detect, in a sleep mode, voltage data of each battery unit in a lithium iron phosphate battery pack;

In an aspect of an embodiment of the present invention, a battery system including a lithium iron phosphate battery pack and the above battery management system is provided.

The aspect as described above and any possible implementation manner further provide an implementation manner, wherein the lithium iron phosphate battery pack includes a lithium ion battery bill having a solid content of lithium iron phosphate in the cathode active material of greater than or equal to 90%. body.

It can be seen from the above technical solutions that the embodiments of the present invention have the following beneficial effects:

In the technical solution provided by the embodiment of the present invention, whether the equalization start is satisfied is determined according to the difference between the state of charge of the lithium iron phosphate battery pack and the voltage data of each battery cell in the lithium iron phosphate battery pack and the minimum voltage value. Condition, if the equalization start condition is satisfied, that is, the state of charge is at the low end (ie, the state of charge is at 10% to 40%), and there is a battery unit whose difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold, Discharging the battery unit that satisfies the equalization starting condition, so that the voltage of the battery unit with higher voltage data in the lithium iron phosphate battery pack tends to be consistent with the minimum voltage value, thereby reducing the imbalance of charge between the battery units. Degree, effectively achieves the charge balance between the battery cells, thereby avoiding the problem of the power capability and available energy of the lithium iron phosphate battery system caused by the large imbalance of the charge, and prolonging the lithium iron phosphate battery The life of the bag. Moreover, the equalization efficiency of the lithium iron phosphate battery pack can be effectively improved by the low-end equalization.

[Description of the Drawings]

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the present invention. One of ordinary skill in the art can also obtain other drawings based on these drawings without paying for inventive labor.

1 is a schematic flow chart of Embodiment 1 of a method for equalizing a battery pack according to an embodiment of the present invention;

2 is a schematic flow chart of Embodiment 2 of a battery pack equalization method according to an embodiment of the present invention;

3 is a graph showing a relationship between a state of charge and a voltage of a lithium iron phosphate battery pack according to an embodiment of the present invention;

4 is a schematic flow chart of Embodiment 3 of a battery pack equalization method according to an embodiment of the present invention;

FIG. 5 is a functional block diagram of Embodiment 1 of a battery management system according to an embodiment of the present invention; FIG.

6 is a functional block diagram of Embodiment 2 of a battery management system according to an embodiment of the present invention;

FIG. 7 is a functional block diagram of a battery system according to an embodiment of the present invention.

【detailed description】

For a better understanding of the technical solutions of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

It should be understood that the described embodiments are only a part of the embodiments of the invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

The terms used in the embodiments of the present invention are for the purpose of describing particular embodiments only and are not intended to limit the invention. The singular forms "a", "the" and "the"

It should be understood that the term "and/or" as used herein is merely an association describing the associated object, indicating that there may be three relationships, for example, A and/or B, which may indicate that A exists separately, while A and B, there are three cases of B alone. In addition, the character "/" in this article generally indicates that the contextual object is an "or" relationship.

Depending on the context, the word "if" as used herein may be interpreted as "when" or "when" or "in response to a determination" or "in response to Detection". Similarly, depending on the context, the phrase "if determined" or "if detected (conditions or events stated)" may be interpreted as "when determined" or "in response to determination" or "when detected (stated condition or event) "Time" or "in response to a test (condition or event stated)".

Lithium iron phosphate battery pack has a typical charging and discharging platform. This excellent electrical performance, high cycle life and high safety make this product widely used in electric vehicles and energy storage. The lithium iron phosphate battery system consists of a lithium iron phosphate battery pack and a battery management system. The lithium iron phosphate battery pack consists of a large number of battery cells connected in series or in parallel or mixed. Due to variations in raw materials and manufacturing processes, the state of charge between battery cells is not exactly the same. As a result, during the use of the lithium iron phosphate battery system, after repeated charging, discharging and calendar storage, the charging imbalance between the battery cells gradually increases, directly affecting the power capability of the lithium iron phosphate battery system. And the use of available energy, reducing the service life of lithium iron phosphate battery pack. Therefore, it is very necessary to balance the lithium iron phosphate battery pack.

There are two main methods for equalizing lithium iron phosphate battery packs, one is the high-end equalization method, and the other is the low-end equalization method. It should be noted that the low-end equalization refers to starting the equalization when the state of charge is between 10% and 40% and the differential pressure meets the equilibrium start condition. The high-end equalization refers to the state of charge at 90% to 100% and the pressure difference. Start balancing under the equilibrium start condition. Before the equalization method was selected, different experiments were performed on several samples. As shown in Table 1, the high-end equilibrium used three lithium iron phosphate battery pack samples for experimentation. Before the high-end equalization, the charge imbalance was 17.1. %, 27.6%, 22.9%, after the high-end equilibrium, the charge imbalance of the three samples became 13.5%, 20.4%, and 22.9%, respectively. The difference between the average value of the voltage and the minimum voltage value, that is, the differential pressure in the table, is reduced from 24 mV, 29 mV, and 7 mV to 5 mV, 4 mV, and 6 mV, respectively. It can be understood that the charging imbalance ΔSoC can be calculated in two ways, one is the difference between the average value of the state of charge of each battery cell in the lithium iron phosphate battery pack and the minimum value of the state of charge. The other is the difference between the maximum value of the state of charge of each battery cell in the lithium iron phosphate battery pack and the minimum value of the state of charge. The degree of charge imbalance mentioned in this embodiment is the difference between the average value of the state of charge of each battery cell in the lithium iron phosphate battery pack and the minimum value of the state of charge. Five samples were used to equalize the lithium iron phosphate battery pack using a low-end equalization method, and two of the samples, sample 2 and sample 3, were identical to those used for high-end equalization. It can be seen from Table 1 that the five samples pass the low-end equilibrium mode, and the charge imbalance is reduced from 27.6%, 22.9%, 6.1%, 5.4%, 4.8% to 2.0%, 1.6%, and 1.8%, respectively. 1.3%, 1.1%, the differential pressure is reduced from 16mV, 62mV, 26mV, 24mV, 18mV to 8mV, 8mV, 6mV, 4mV, 4mV. It can be seen that the low-end equalization is more obvious than the high-end equalization, and the improvement of the charging imbalance between the battery cells in the lithium iron phosphate battery pack is more obvious. Therefore, the effective equalization methods involved in the following embodiments are all low-end equalization methods.

Table 1

Embodiment 1

The embodiment of the present invention provides a battery pack equalization method. Referring to FIG. 1 , it is a schematic flowchart of Embodiment 1 of a battery pack equalization method according to an embodiment of the present invention. As shown in the figure, the method includes the following steps:

S101. Detecting voltage data of each battery cell in the lithium iron phosphate battery pack, and acquiring a state of charge of the lithium iron phosphate battery pack according to voltage data of each battery unit.

S102. Acquire a minimum voltage value in the voltage data.

S103, determining whether the state of charge is located at 10% to 40%, and respectively comparing a difference between voltage data of each battery cell in the lithium iron phosphate battery pack and the minimum voltage value with a preset voltage threshold. Compare.

S104. If it is determined that the state of charge is between 10% and 40%, and there is a battery unit whose difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold, the lithium iron phosphate battery is The battery unit in which the difference between the voltage data in the packet and the minimum voltage value is greater than or equal to the voltage threshold performs discharge.

Embodiment 2

Please refer to FIG. 2 , which is a schematic flowchart of Embodiment 2 of a battery pack balancing method according to an embodiment of the present invention. This embodiment is a specific implementation method of Embodiment 1. As shown, the method includes the following steps:

S201, detecting voltage data of each battery unit in the lithium iron phosphate battery pack, and according to each battery list The voltage data of the element obtains the state of charge of the lithium iron phosphate battery pack.

Specifically, in the embodiment of the present invention, the voltage data of each battery unit in the lithium iron phosphate battery pack can be detected in the sleep mode.

It should be noted that the sleep mode refers to that the lithium iron phosphate battery pack has no input energy or output energy.

It should be noted that, in the embodiment of the present invention, a lithium iron phosphate battery pack is generally composed of a plurality of battery cells connected in series or in parallel or mixed. Wherein, each battery unit may include one battery unit, or each battery unit may also include at least two battery cells connected in parallel, that is, each battery unit may be composed of a plurality of battery cells connected in parallel. of.

In an embodiment of the invention, each of the battery cells of the lithium iron phosphate battery pack comprises a lithium ion battery cell having a solid content of lithium iron phosphate in the cathode active material of greater than or equal to 90%.

In the implementation of the present invention, the discharge process may be completed intermittently before the voltage data of the battery unit discharged in the lithium iron phosphate battery pack reaches a preset condition, that is, after the discharge is continued for a preset period of time 1, the iron phosphate battery pack After entering the sleep mode, the duration of maintaining the sleep mode reaches the preset duration of 2, and then wakes up the battery management system and re-executes the equalization process of S201 to S207. The preset duration 1 and the preset duration 2 can be comprehensively considered and set according to the hardware characteristics of the execution body of the equalization operation and the equalization efficiency, for example, 5 minutes, 10 minutes, 1 hour, or 3 hours, etc., can be preset. The duration 1 and the preset duration 2 may be the same or different.

When the lithium iron phosphate battery pack is in the sleep mode, the state of charge data of each battery unit in the lithium iron phosphate battery pack is detected, and the state of charge indicates the remaining capacity of the battery after being used for a period of time or for a long period of time. The ratio of the capacity of the fully charged state can be expressed in percentage.

In the embodiment of the present invention, the voltage data of each battery unit in the lithium iron phosphate battery pack can be detected and recorded. For example, the voltage data of each battery unit can be sequentially recorded as U ₁ , U ₂ , ..., U. _N , where N represents the number of battery cells in the lithium iron phosphate battery pack.

In the embodiment of the present invention, after detecting the voltage data of each battery unit in the lithium iron phosphate battery pack, the iron phosphate can be quickly obtained according to the voltage data of each battery unit in the lithium iron phosphate battery pack. The state of charge of the lithium battery pack.

It should be noted that the state of charge refers to the ratio of the remaining amount of electricity to the amount of charge after the use of the lithium iron phosphate battery pack for a period of time or after being used for a long period of time, and can be expressed as a percentage.

S202. Acquire a minimum voltage value in the voltage data.

For example, the voltage data of each battery cell can be sorted according to the order of largest to small to obtain the minimum voltage value therein. Alternatively, the voltage data of each battery cell may be sorted according to the order from small to large to obtain the minimum voltage value therein.

S203, determining whether the state of charge is located at 10% to 40%, and respectively comparing a difference between voltage data of each battery cell in the lithium iron phosphate battery pack and the minimum voltage value with a preset voltage threshold. Compare. If it is determined that the state of charge is between 10% and 40%, and there is a battery cell whose difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold, S204 is performed; otherwise, S207 is performed.

Specifically, after obtaining the state of charge of the lithium iron phosphate battery pack, it is further determined whether the state of charge is located at 10% to 40%, and simultaneously calculating the difference between the voltage data and the minimum voltage value of each battery unit. For example, the pressure difference of each battery cell is expressed as ΔU=U _i -min{U ₁ , U ₂ , U ₃ , . . . , U _N }, where i=1, 2, 3, . . . , N; The differences are each compared to a preset voltage threshold.

If the state of charge is between 10% and 40%, and there is a battery unit where the difference between the at least one voltage data and the minimum voltage value is greater than or equal to the voltage threshold, the state of charge of the lithium iron phosphate battery pack is The lower end satisfies the equalization start condition, and indicates that the difference between the voltage data of the at least one battery cell and the minimum voltage value is large, and it is necessary to perform discharge on the battery cells in the lithium iron phosphate battery pack, so the process proceeds to S204. Otherwise, in other cases, S207 is performed.

Wherein, the other situation includes: the state of charge is between 10% and 40%, but there is no battery unit whose difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold. Alternatively, the state of charge is not between 10% and 40%, but there is a battery cell whose difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold. Or, the state of charge is not located at 10% to 40%, and the difference between the absence of the voltage data and the minimum voltage value is greater than or equal to the voltage threshold. Battery unit.

It should be noted that the difference between the voltage data of all the battery cells and the minimum voltage value is less than the voltage threshold, indicating that the difference between the voltage data and the minimum voltage value of the battery unit is small, and The charge balancing is performed, so S207 is executed. Moreover, if the state of charge is not located at 10% to 40%, it indicates that the state of charge of the lithium iron phosphate battery pack is not at the low end, and may be in other charging intervals (such as 0 to 10% or 40% to 100%), Satisfying the equalization start condition, it is not necessary to perform discharge on the battery cells in the lithium iron phosphate battery pack, so S207 is performed.

Among them, the preset voltage threshold can be determined experimentally. For example, the preset voltage threshold can be equal to 8 mV.

It should be noted that, in the embodiment of the present invention, whether the difference between the voltage data and the minimum voltage value of each battery cell in the lithium iron phosphate battery pack and the state of charge of the lithium iron phosphate battery pack are determined is determined whether the balance is satisfied. The start condition, if the equalization start condition is satisfied, the equalization operation of the battery unit is performed. On the other hand, if the equalization start condition is not satisfied, or the equalization operation of the battery unit is not performed, the current flow is ended.

Please refer to FIG. 3 , which is a graph showing the relationship between the state of charge and the voltage of a lithium iron phosphate battery pack according to an embodiment of the present invention. The relationship diagram can be performed on a battery unit in a lithium iron phosphate battery pack by a charging and discharging device. Tested. As shown in FIG. 3, when the state of charge of the lithium iron phosphate battery pack is in the range of 10% to 40%, the state of charge has a strong correlation with the voltage. Therefore, in this interval, the voltage data of each battery cell is estimated and Correcting the state of charge can improve the accuracy of the calculated state of charge, and thus the equalization effect is good. In the interval of 10% to 40%, preferably, the state of charge state may be 15% to 35%.

It should be noted that when the state of charge of the lithium iron phosphate battery pack is 90% to 100%, the interval is narrow, and the polarization characteristics of the lithium iron phosphate material and the difference between the battery cells in the lithium iron phosphate battery pack are required. Sex, the voltage drops to the platform area, the pressure difference is small, and it is not easy to trigger the equalization or trigger the equalization and the implementation effect is not good. When the state of charge is 40% to 90% in the platform area, there is almost no correlation between the state of charge and the voltage in this region, and it is impossible to trigger equalization or cause misbalance. When the state of charge is 0 to 10%, in order to prevent the battery unit in the lithium iron phosphate battery pack from being over-discharged, it cannot be used as an equalization interval. The end-equalization method is to equalize the battery cells in the lithium iron phosphate battery pack, and it is necessary to carry out the charging state of the lithium iron phosphate battery pack at 10% to 40%.

S204. Perform discharge on a battery unit in which a difference between voltage data and the minimum voltage value in the lithium iron phosphate battery pack is greater than or equal to the voltage threshold.

Specifically, in the embodiment of the present invention, it is determined that the state of charge of the lithium iron phosphate battery pack is 10% to 40%, and the difference between the voltage data and the minimum voltage value in the lithium iron phosphate battery pack is greater than or equal to When the battery unit of the voltage threshold is used, the battery unit in which the difference between the voltage data and the minimum voltage value in the lithium iron phosphate battery pack is greater than or equal to the voltage threshold is discharged, so that the discharge can be made to make the lithium iron phosphate battery pack After the battery with higher voltage is discharged, the voltage data is consistent with the voltage of the battery unit with the smallest voltage data in the lithium iron phosphate battery pack, thereby achieving the balance of the lithium iron phosphate battery pack and reducing the charging of the lithium iron phosphate battery pack. Unbalanced.

S205. Determine whether the voltage data of the battery cells discharged in the iron phosphate battery pack reaches a specified condition. If yes, execute S206, and if no, execute S201.

Specifically, in the embodiment of the present invention, after performing discharge on the battery unit in which the difference between the voltage data and the minimum voltage value in the lithium iron phosphate battery pack is greater than or equal to the voltage threshold, the phosphoric acid needs to be judged. Whether the voltage data of the battery cells discharged in the iron battery pack reaches the specified condition, and if it is determined that the voltage data of the battery cells discharged in the iron phosphate battery pack reaches the specified condition, S206 is performed. On the other hand, if it is judged that the voltage data of the battery cells discharged in the iron phosphate battery pack does not reach the specified condition, S201 is executed, that is, the operations of detecting, estimating, judging, and equalizing are performed again.

In a specific implementation process, the specifying condition may include: voltage data of the discharged battery cells in the iron phosphate battery pack is consistent with the minimum voltage value.

S206, stopping discharging of the battery unit whose difference between the voltage data and the minimum voltage value in the iron phosphate battery pack is greater than or equal to the voltage threshold.

Specifically, in the embodiment of the present invention, after performing discharge on the battery unit in which the difference between the voltage data and the minimum voltage value in the lithium iron phosphate battery pack is greater than or equal to the voltage threshold, it is necessary to determine the iron phosphate. When the voltage data of the battery unit discharged in the battery pack reaches the specified condition, the pair is stopped. The difference between the voltage data in the iron phosphate battery pack and the minimum voltage value is greater than or equal to the discharge of the battery unit of the voltage threshold, and after stopping the discharge of the battery unit, the lithium iron phosphate battery is realized. The charge balance of the package.

S207, discharge is not performed on the battery cells in the lithium iron phosphate battery pack, and the flow is ended.

Embodiment 3

Please refer to FIG. 4 , which is a schematic flowchart of Embodiment 3 of a battery pack balancing method according to an embodiment of the present invention. This embodiment is another specific implementation method of Embodiment 1. As shown, the method includes the following steps:

In S401, the lithium iron phosphate battery pack is fully charged, and then discharged to a lithium iron phosphate battery pack with a state of charge of 20% to 25%.

S402, in the sleep mode, detecting and recording the voltage data of the 100 battery cells connected in series in the lithium iron phosphate battery pack, denoted as U _N , and N is equal to 1, 2, 3, ..., 100.

S403. Calculate a difference between voltage data and a minimum voltage value of each battery cell in the lithium iron phosphate battery pack.

S404, discharging a battery unit having a difference between a voltage data and a minimum voltage value in the lithium iron phosphate battery pack of greater than 8 mV.

S405, re-executing the low-end equalization of the lithium iron phosphate battery pack every time interval, that is, executing S401-S405, until the voltage data of the battery unit with higher voltage data and the voltage minimum tend to coincide, completing the lithium iron phosphate battery The balance of the package.

Embodiments of the present invention further provide an apparatus embodiment for implementing the steps and methods in the foregoing method embodiments.

Please refer to FIG. 5 , which is a functional block diagram of Embodiment 1 of a battery management system according to an embodiment of the present invention. As shown, the battery management system includes:

The detecting module 51 is configured to detect voltage data of each battery unit in the lithium iron phosphate battery pack;

The power estimation module 52 is configured to acquire, according to voltage data of each battery unit, a state of charge of the lithium iron phosphate battery pack;

The equalization module 53 is configured to acquire a minimum voltage value in the voltage data; and determine the Whether the electrical state is between 10% and 40%, and respectively comparing the difference between the voltage data of each battery cell in the lithium iron phosphate battery pack and the minimum voltage value with a preset voltage threshold; and, if Determining that the state of charge is between 10% and 40%, and there is a battery cell whose difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold, and the voltage in the lithium iron phosphate battery pack The battery unit whose difference between the data and the minimum voltage value is greater than or equal to the voltage threshold performs discharge.

Optionally, the equalization module 53 is further configured to:

Preferably, the specified condition includes: voltage data of the discharged battery cells in the iron phosphate battery pack is consistent with the minimum voltage value.

Preferably, the detecting module 51 is configured to: detect, in a sleep mode, voltage data of each battery unit in the lithium iron phosphate battery pack; wherein the sleep mode includes that the lithium iron phosphate battery pack has no input energy or Output energy.

Preferably, each battery unit comprises one battery cell, or each battery cell comprises at least two battery cells in parallel.

Preferably, each of the battery cells in the lithium iron phosphate battery pack comprises a lithium ion battery cell having a solid content of lithium iron phosphate in the cathode active material of greater than or equal to 90%.

Since each unit in this embodiment can perform the method shown in FIG. 1, FIG. 2 or FIG. 4, and the parts not described in detail in this embodiment, reference may be made to the related description of FIG. 1, FIG. 2 or FIG.

Please refer to FIG. 6 , which is a functional block diagram of Embodiment 2 of a battery management system according to an embodiment of the present invention. As shown in the figure, the battery management system may further include: a charging module 54 for charging the lithium iron phosphate battery pack, and then discharging to a lithium iron phosphate battery pack with a state of charge of 10% to 40%.

Please refer to FIG. 7, which is a functional block diagram of a battery system according to an embodiment of the present invention. As shown in FIG. 7, the battery system includes a lithium iron phosphate battery pack 70 and the above battery management system 71.

It can be understood that the lithium iron phosphate battery pack includes lithium iron phosphate in the cathode active material. A lithium ion battery cell having a solid content greater than or equal to 90%.

The technical solution of the embodiment of the invention has the following beneficial effects:

In the technical solution provided by the embodiment of the present invention, whether the equalization start is satisfied is determined according to the difference between the state of charge of the lithium iron phosphate battery pack and the voltage data of each battery cell in the lithium iron phosphate battery pack and the minimum voltage value. Condition, if the equilibrium is satisfied, that is, the state of charge is at the low end (the state of charge is at 10% to 40%), and there is a battery cell whose difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold, then The battery unit that satisfies the equalization starting condition is discharged, so that the voltage of the battery unit with higher voltage data in the lithium iron phosphate battery pack tends to be consistent with the minimum voltage value, thereby reducing the imbalance of the charging between the battery units. The utility model can effectively realize the charge balance between the battery cells, thereby avoiding the problem of the power capability and the available energy of the lithium iron phosphate battery system caused by the large imbalance of the charge, and prolonging the lithium iron phosphate battery pack. The service life. Moreover, the equalization efficiency of the lithium iron phosphate battery pack can be effectively improved by the low-end equalization.

In addition, the technical solution provided by the embodiment of the present invention is better than the prior art in other charging states (the state of charge is 40% to 100%), and the charging balancing effect is better, and the error balancing can be prevented. The balance effect is improved, the imbalance of the charge between the battery cells is minimized, and the inconsistency between the battery cells is improved, thereby prolonging the service life of the lithium iron phosphate battery pack.

A person skilled in the art can clearly understand that for the convenience and brevity of the description, the specific working process of the system, the device and the unit described above can refer to the corresponding process in the foregoing method embodiment, and details are not described herein again.

In the several embodiments provided by the present invention, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the device embodiments described above are merely illustrative. For example, the division of the unit is only a logical function division. In actual implementation, there may be another division manner. For example, multiple units or components may be combined. Or it can be integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be in an electrical, mechanical or other form.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of hardware plus software functional units.

The above-described integrated unit implemented in the form of a software functional unit can be stored in a computer readable storage medium. The above software functional unit is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor to perform the methods of the various embodiments of the present invention. Part of the steps. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, and the like, which can store program codes. .

The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalents, improvements, etc., which are made within the spirit and principles of the present invention, should be included in the present invention. Within the scope of protection.

Claims

A battery pack equalization method, comprising:

Detecting voltage data of each battery cell in the lithium iron phosphate battery pack, and acquiring a state of charge of the lithium iron phosphate battery pack according to voltage data of each battery unit;

Obtaining a minimum voltage value in the voltage data;

Determining whether the state of charge is between 10% and 40%, and comparing the difference between the voltage data of each battery cell in the lithium iron phosphate battery pack and the minimum voltage value and a preset voltage threshold ;

If it is determined that the state of charge is between 10% and 40%, and there is a battery unit whose difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold, in the lithium iron phosphate battery pack A battery unit having a difference between the voltage data and the minimum voltage value greater than or equal to the voltage threshold performs discharge.
The battery pack equalization method according to claim 1, wherein the method further comprises:

Stopping, when the voltage data of the discharged battery cells in the iron phosphate battery pack reaches a specified condition, a difference between a voltage data in the iron phosphate battery pack and the minimum voltage value is greater than or equal to the voltage The discharge of the battery cells of the threshold.
The battery pack equalization method according to claim 2, wherein the specified condition comprises: voltage data of the discharged battery cells in the iron phosphate battery pack is consistent with the minimum voltage value.
The battery pack equalization method according to claim 1, wherein detecting voltage data of each battery unit in the lithium iron phosphate battery pack comprises:

In the sleep mode, detecting voltage data of each battery cell in the lithium iron phosphate battery pack;

The sleep mode includes the lithium iron phosphate battery pack having no input energy or output energy.
The battery pack equalization method according to any one of claims 1 to 4, wherein each of the battery cells includes one battery cell, or each of the battery cells includes at least two battery cells connected in parallel.
The battery pack equalization method according to claim 5, wherein said lithium iron phosphate battery Each of the battery cells in the cell pack includes a lithium ion battery cell having a solid content of lithium iron phosphate in the cathode active material of greater than or equal to 90%.
A battery management system, characterized in that the battery management system comprises:

a detecting module for detecting voltage data of each battery unit in the lithium iron phosphate battery pack;

a power estimation module, configured to acquire, according to voltage data of each battery unit, a state of charge of the lithium iron phosphate battery pack;

An equalization module, configured to obtain a minimum voltage value in the voltage data; and, determining whether the state of charge is located at 10% to 40%, and respectively comparing voltage data of each battery unit in the lithium iron phosphate battery pack Comparing the difference between the minimum voltage values with a preset voltage threshold; and, if it is determined that the state of charge is between 10% and 40%, and there is a difference between the voltage data and the minimum voltage value The battery unit having a value greater than or equal to the voltage threshold performs discharging on a battery unit in which a difference between voltage data and the minimum voltage value in the lithium iron phosphate battery pack is greater than or equal to the voltage threshold.
The battery management system according to claim 7, wherein the equalization module is further configured to:

Stopping, when the voltage data of the discharged battery cells in the iron phosphate battery pack reaches a specified condition, a difference between a voltage data in the iron phosphate battery pack and the minimum voltage value is greater than or equal to the voltage The discharge of the battery cells of the threshold.
The battery management system according to claim 8, wherein said specified condition comprises: voltage data of said discharged battery cells in said iron phosphate battery pack is identical to said minimum voltage value.
The battery management system according to claim 7, wherein the detecting module is configured to: detect voltage data of each battery unit in the lithium iron phosphate battery pack in a sleep mode;

The sleep mode includes the lithium iron phosphate battery pack having no input energy or output energy.
A battery management system according to any one of claims 7 to 10, wherein each of the battery cells comprises one battery cell, or each battery cell comprises at least two battery cells in parallel.
A battery system comprising a lithium iron phosphate battery pack and the battery management system according to any one of claims 7 to 11.
The battery system according to claim 12, wherein said lithium iron phosphate battery pack comprises a lithium ion battery cell having a solid content of lithium iron phosphate in the cathode active material of greater than or equal to 90%.