CN108780927B - Battery pack balancing method, battery management system and battery system - Google Patents
Battery pack balancing method, battery management system and battery system Download PDFInfo
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- CN108780927B CN108780927B CN201680081297.6A CN201680081297A CN108780927B CN 108780927 B CN108780927 B CN 108780927B CN 201680081297 A CN201680081297 A CN 201680081297A CN 108780927 B CN108780927 B CN 108780927B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
A battery pack balancing method, a battery management system and a battery system are provided. The equalization method comprises the following steps: the method comprises the steps of detecting voltage data of each battery unit in the lithium iron phosphate battery pack, obtaining the state of charge of the lithium iron phosphate battery pack according to the voltage data of each battery unit (S101), and obtaining the minimum voltage value in the voltage data (S102); accordingly, whether the state of charge is 10% -40% or not is judged, and the difference value between the voltage data and the minimum voltage value of each battery unit in the lithium iron phosphate battery pack is compared with a preset voltage threshold value (S103); and if the state of charge is judged to be between 10 and 40 percent, and a battery unit with the difference value between the voltage data and the minimum voltage value being greater than or equal to the voltage threshold value exists, discharging the battery unit (S104). The uniformity of the state of charge among the battery units in the lithium iron phosphate battery pack is improved through the balancing method, and the service life of the lithium iron phosphate battery pack is prolonged.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to the technical field of batteries, in particular to a battery pack balancing method, a battery management system and a battery system.
[ background of the invention ]
Lithium iron phosphate battery pack (LiFePO)4Battery Pack) has a typical charge-discharge platform, and the excellent electrical property, the characteristics of long cycle life and high safety make the product widely applied to the fields of electric automobiles 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 is formed by connecting a plurality of battery units in series or in parallel or in series-parallel. Since the battery cells vary in the raw materials and manufacturing processes, the states of Charge (SoC) of the battery cells are not completely the same. Therefore, the lithium iron phosphate battery system is repeatedly charged, discharged and stored in a calendar in the using process, the charge imbalance among the battery units is gradually increased, the power capacity and the available energy of the lithium iron phosphate battery system are directly influenced, and the service life of the lithium iron phosphate battery pack is shortened.
[ summary of the invention ]
In view of this, the invention provides a battery pack balancing method, a battery management system and a battery system, which improve the consistency of the state of charge among the battery units in the lithium iron phosphate battery pack and prolong the service life of the lithium iron phosphate battery pack.
In one aspect of the embodiments of the present invention, a battery pack balancing method is provided, including:
detecting voltage data of each battery unit in the lithium iron phosphate battery pack, and acquiring the charge state of the lithium iron phosphate battery pack according to the voltage data of each battery unit;
acquiring a minimum voltage value in the voltage data;
judging whether the state of charge is 10% -40%, and comparing the difference between the voltage data of each battery unit in the lithium iron phosphate battery pack and the minimum voltage value with a preset voltage threshold value respectively;
and if the state of charge is judged to be 10% -40%, and a battery unit with the difference value between the voltage data and the minimum voltage value larger than or equal to the voltage threshold value exists, discharging the battery unit with the difference value between the voltage data and the minimum voltage value larger than or equal to the voltage threshold value in the lithium iron phosphate battery pack.
The above-described aspects and any possible implementations further provide an implementation, and the method further includes:
and when the voltage data of the discharged battery unit in the iron-based physical battery pack reaches a specified condition, stopping discharging the battery unit of which the difference value between the voltage data in the iron-based physical battery pack and the minimum voltage value is greater than or equal to the voltage threshold value.
The above-described aspect and any possible implementation further provide an implementation, where the specifying conditions include: and the voltage data of the discharged battery unit in the iron-based battery pack is consistent with the minimum voltage value.
The above-described aspects and any possible implementation manners further provide an implementation manner for detecting voltage data of each battery unit in a lithium iron phosphate battery pack, including:
detecting voltage data of each battery unit in the lithium iron phosphate battery pack in a sleep mode;
wherein the sleep mode includes no input energy or output energy of the lithium iron phosphate battery pack.
The above-described aspect and any possible implementation manner further provide an implementation manner, where each battery unit includes one battery cell, or each battery unit includes at least two battery cells connected in parallel.
The above aspects and any possible implementation manners further provide an implementation manner, where each battery cell in the lithium iron phosphate battery pack includes a lithium ion battery cell in which solid content of lithium iron phosphate in a cathode active material is greater than or equal to 90%.
In one aspect of the embodiments of the present invention, a battery management system is provided, including:
the detection module is used for detecting voltage data of each battery unit in the lithium iron phosphate battery pack;
the electric quantity estimation module is used for acquiring the charge state of the lithium iron phosphate battery pack according to the voltage data of each battery unit;
the balancing module is used for acquiring a minimum voltage value in the voltage data; judging whether the state of charge is 10% -40%, and comparing the difference between the voltage data of each battery unit in the lithium iron phosphate battery pack and the minimum voltage value with a preset voltage threshold value; and if the state of charge is judged to be 10% -40%, and a battery unit with a difference value between the voltage data and the minimum voltage value larger than or equal to the voltage threshold value exists, discharging the battery unit with the difference value between the voltage data and the minimum voltage value larger than or equal to the voltage threshold value in the lithium iron phosphate battery pack.
The above-described aspect and any possible implementation further provide an implementation, where the equalizing module is further configured to:
and when the voltage data of the discharged battery unit in the iron-based physical battery pack reaches a specified condition, stopping discharging the battery unit of which the difference value between the voltage data in the iron-based physical battery pack and the minimum voltage value is greater than or equal to the voltage threshold value.
The above-described aspect and any possible implementation further provide an implementation, where the specifying conditions include: and the voltage data of the discharged battery unit in the iron-based battery pack is consistent with the minimum voltage value.
The above-described aspect and any possible implementation further provide an implementation, where the detection module is specifically configured to: detecting voltage data of each battery unit in the lithium iron phosphate battery pack in a sleep mode;
wherein the sleep mode includes no input energy or output energy of the lithium iron phosphate battery pack.
The above-described aspect and any possible implementation manner further provide an implementation manner, where each battery unit includes one battery cell, or each battery unit includes at least two battery cells connected in parallel.
In one aspect of the embodiments of the present invention, a battery system is provided, which includes a lithium iron phosphate battery pack and the above battery management system.
The above aspects and any possible implementation manners further provide an implementation manner, in which the lithium iron phosphate battery pack includes a lithium ion battery cell in which solid content of lithium iron phosphate in a cathode active material is greater than or equal to 90%.
According to the technical scheme, the embodiment of the invention has the following beneficial effects:
in the technical scheme provided by the embodiment of the invention, whether an equilibrium starting condition is met is judged according to the charge state of the lithium iron phosphate battery pack and the difference value between the voltage data and the minimum voltage value of each battery unit in the lithium iron phosphate battery pack, if the equilibrium starting condition is met, namely the charge state is at the low end (namely the charge state is between 10 and 40 percent), and the battery units meeting the equilibrium starting condition exist, wherein the difference value between the voltage data and the minimum voltage value is more than or equal to the voltage threshold value, the battery units meeting the equilibrium starting condition are discharged, so that the voltage of the battery units with higher voltage data in the lithium iron phosphate battery pack tends to be consistent with the minimum voltage value, the charge imbalance among the battery units is reduced, the charge equalization among the battery units is effectively realized, and the problems of power capacity and available energy exertion of the lithium iron phosphate battery system caused by the larger charge imbalance are solved, the service life of the lithium iron phosphate battery pack is prolonged. And the balance efficiency of the lithium iron phosphate battery pack can be effectively improved through low-end balance.
[ description of the drawings ]
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive labor.
Fig. 1 is a schematic flowchart of a battery pack balancing method according to a first embodiment of the present invention;
fig. 2 is a schematic flow chart of a battery pack balancing method according to a second embodiment of the present invention;
fig. 3 is a graph of state of charge versus voltage for a lithium iron phosphate battery pack according to an embodiment of the present invention;
fig. 4 is a schematic flowchart of a third embodiment of a battery pack balancing method according to the present invention;
fig. 5 is a functional block diagram of a first embodiment of a battery management system according to the present invention;
fig. 6 is a functional block diagram of a second embodiment of a battery management system according to the present invention;
fig. 7 is a functional block diagram of a battery system according to an embodiment of the present invention.
[ detailed description ] embodiments
For better understanding of the technical solutions of the present invention, the following detailed descriptions of the embodiments of the present invention are provided with reference to the accompanying drawings.
It should be understood that the described embodiments are only some embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
The word "if," as used herein, may be interpreted as "when or" in response to determining "or" in response to detecting, "depending on the context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context.
The lithium iron phosphate battery pack has a typical charging and discharging platform, and the characteristics of excellent electrical property, long cycle life and high safety enable the product to be widely applied to the fields of electric automobiles 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 is formed by connecting a plurality of battery units in series or in parallel or in series-parallel. The state of charge of the battery cells is not completely the same due to variations in the raw materials and manufacturing processes of the battery cells. Therefore, the lithium iron phosphate battery system is repeatedly charged, discharged and stored in a calendar in the using process, the charge imbalance among the battery units is gradually increased, the power capacity and the available energy of the lithium iron phosphate battery system are directly influenced, and the service life of the lithium iron phosphate battery pack is shortened. Therefore, it is very necessary to balance the lithium iron phosphate battery pack.
There are two main methods for balancing lithium iron phosphate battery packs, one is a high-end balancing method, and the other is a low-end balancing method. It should be noted that the low-end equalization refers to starting equalization when the state of charge is 10% to 40% and the pressure difference satisfies the equalization start condition, and the high-end equalization refers to starting equalization when the state of charge is 90% to 100% and the pressure difference satisfies the equalization start condition. Before the balancing method is selected, different experiments are performed on a plurality of samples, as shown in table 1, three lithium iron phosphate battery pack samples are used for performing the experiments in the high-end balancing mode, the charge unbalance degrees of the three samples are respectively 17.1%, 27.6% and 22.9% before the high-end balancing mode, and the charge unbalance degrees of the three samples are respectively 13.5%, 20.4% and 22.9% after the high-end balancing mode. The difference between the sum of the average voltage values and the minimum voltage value, i.e. the voltage difference in the table, was reduced from 24mV, 29mV, 7mV to 5mV, 4mV, 6mV, respectively. It is understood that the degree of charge imbalance Δ SoC can be calculated by the difference between the average value of the states of charge of the battery cells in the lithium iron phosphate battery pack and the minimum value of the states of charge, or by the difference between the maximum value of the states of charge of the battery cells in the lithium iron phosphate battery pack and the minimum value of the states of charge. The charge imbalance referred to in this embodiment is the difference between the average value of the states of charge of the battery cells in the lithium iron phosphate battery pack and the minimum value of the states of charge. When the lithium iron phosphate battery pack is balanced by adopting a low-end balancing method, five samples are used, and two samples, namely sample 2 and sample 3, are the same as the samples used in high-end balancing. As can be seen from Table 1, the charge imbalance of the five samples is reduced from 27.6%, 22.9%, 6.1%, 5.4% and 4.8% to 2.0%, 1.6%, 1.8%, 1.3% and 1.1% respectively by low-end equalization, and the differential pressure is reduced from 16mV, 62mV, 26mV, 24mV and 18mV to 8mV, 6mV, 4mV and 4mV respectively. Therefore, compared with the high-end balance, the low-end balance has the advantage that the charge imbalance among the battery units in the lithium iron phosphate battery pack is improved more obviously. Therefore, the following embodiments refer to effective equalization methods that are low-end equalization methods.
TABLE 1
Example one
An embodiment of the present invention provides a battery pack balancing method, please refer to fig. 1, which is a schematic flow chart of a first embodiment of the battery pack balancing method provided in the embodiment of the present invention, as shown in the figure, the method includes the following steps:
s101, detecting voltage data of each battery unit in the lithium iron phosphate battery pack, and acquiring the charge state of the lithium iron phosphate battery pack according to the voltage data of each battery unit.
And S102, acquiring the minimum voltage value in the voltage data.
S103, judging whether the state of charge is 10% -40%, and comparing the difference value between the voltage data of each battery unit in the lithium iron phosphate battery pack and the minimum voltage value with a preset voltage threshold value.
And S104, if the state of charge is judged to be 10% -40%, and a battery unit with the voltage data and the minimum voltage value larger than or equal to the voltage threshold exists, discharging the battery unit with the voltage data and the minimum voltage value larger than or equal to the voltage threshold in the lithium iron phosphate battery pack.
Example two
Please refer to fig. 2, which is a flowchart illustrating a second embodiment of a battery pack balancing method according to an embodiment of the present invention. As shown, the method comprises the following steps:
s201, detecting voltage data of each battery unit in the lithium iron phosphate battery pack, and acquiring the charge state of the lithium iron phosphate battery pack according to the voltage data of each battery unit.
Specifically, in the embodiment of the 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 the lithium iron phosphate battery pack having no input energy or output energy.
It should be noted that, in the embodiment of the present invention, the lithium iron phosphate battery pack is generally composed of a large number of battery cells connected in series or in parallel or in series-parallel. Each battery unit may include one battery cell, or each battery unit may also include at least two battery cells connected in parallel, that is, each battery unit may be formed by connecting a plurality of battery cells in parallel.
In the embodiment of the invention, each battery cell of the lithium iron phosphate battery pack comprises a lithium ion battery cell of which the solid content of lithium iron phosphate in a cathode active material is greater than or equal to 90%.
In the implementation of the present invention, before the voltage data of the battery cells discharged in the lithium iron phosphate battery pack reaches the preset condition, the discharging process may be intermittently completed, that is, after the discharging lasts for the preset duration 1, the lithium iron phosphate battery pack enters the sleep mode, the duration of the sleep mode is maintained to reach the preset duration 2, and then the battery management system is awakened to re-execute the balancing process of S201 to S207. The preset time length 1 and the preset time length 2 may be comprehensively considered and set according to the hardware characteristic of the execution subject of the equalizing operation and the equalizing efficiency, for example, the preset time length 1 may be the same as or different from the preset time length 2, such as 5 minutes, 10 minutes, 1 hour, or 3 hours.
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, the state of charge represents the ratio of the residual capacity of the storage battery after being used for a period of time or left unused for a long time to the capacity of the storage battery in the full charge state, and can be represented by percentage.
In the embodiment of the 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 recorded as U in sequence1、U2、......、UNWherein N represents the number of battery cells in the lithium iron phosphate battery pack.
In the embodiment of the invention, after the voltage data of each battery unit in the lithium iron phosphate battery pack is detected, the charge state of the lithium iron phosphate battery pack can be quickly obtained according to the voltage data of each battery unit in the lithium iron phosphate battery pack.
It should be noted that the state of charge refers to a ratio of a remaining capacity to a fully charged capacity after the lithium iron phosphate battery pack is used for a period of time or left unused for a long time, and can be expressed by a percentage.
S202, acquiring the minimum voltage value in the voltage data.
For example, the voltage data of each battery unit may be sorted according to a descending order to obtain the minimum voltage value thereof. Or, the voltage data of each battery unit can be sorted according to the sequence from small to large to obtain the minimum voltage value.
S203, judging whether the state of charge is 10% -40%, and comparing the difference value between the voltage data of each battery unit in the lithium iron phosphate battery pack and the minimum voltage value with a preset voltage threshold value. If the state of charge is determined to be 10% -40%, and there are battery cells in which the difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold, executing S204, otherwise, executing S207.
Specifically, after the state of charge of the lithium iron phosphate battery pack is obtained, whether the state of charge is 10% to 40% is further determined, and meanwhile, the difference between the voltage data of each battery unit and the minimum voltage value is respectively calculated, for example, the voltage difference of each battery unit is represented as Δ U ═ Ui-min{U1，U2，U3，…，UNWhere i ═ 1, 2, 3, …, N; and then comparing the calculated difference values with preset voltage threshold values respectively.
If the state of charge is 10% -40%, and there is a battery cell in which the difference between at least one voltage data and the minimum voltage value is greater than or equal to the voltage threshold, it indicates that the state of charge of the lithium iron phosphate battery pack is at a low end, the equilibrium starting condition is satisfied, and it indicates that the difference between the voltage data of the at least one battery cell and the minimum voltage value is large, it is necessary to perform discharging on the battery cell in the lithium iron phosphate battery pack, so S204 is continuously performed. Otherwise, S207 is executed.
Wherein other situations include: the state of charge is between 10% and 40%, but there are no battery cells for which the 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 are battery cells for which the 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 between 10% and 40%, and there are no battery cells for which the difference between the voltage data and the minimum voltage value is greater than or equal to the voltage threshold.
It should be noted that, the difference between the voltage data of all the battery cells and the minimum voltage value is smaller than the voltage threshold, which means that the difference between the voltage data of the battery cell and the minimum voltage value is smaller, and the charge equalization is not required to be performed, so S207 is performed. Moreover, if the state of charge is not in the range of 10% to 40%, which indicates that the state of charge of the lithium iron phosphate battery pack is not at the low end, the lithium iron phosphate battery pack may be in other charge ranges (e.g., 0% to 10% or 40% to 100%), the balanced start condition is not satisfied, and the battery cells in the lithium iron phosphate battery pack do not need to be discharged, so S207 is performed.
The preset voltage threshold value may be determined through experiments. For example, the preset voltage threshold may be equal to 8 mV.
In the embodiment of the present invention, whether the equalization start condition is met is determined according to the difference between the voltage data of each battery unit in the lithium iron phosphate battery pack and the minimum voltage value, and the state of charge of the lithium iron phosphate battery pack, and if the equalization start condition is met, the equalization operation of the battery units is performed. Otherwise, if the equalization starting condition is not met, or the equalization operation of the battery unit is not performed, and the current flow is ended.
Please refer to fig. 3, which is a graph illustrating 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, where the relationship can be obtained by testing battery cells in the lithium iron phosphate battery pack through a charging and discharging device. As shown in fig. 3, when the state of charge of the lithium iron phosphate battery pack is in a range of 10% to 40%, the state of charge has a strong correlation with the voltage, and therefore, in this range, the accuracy of the calculated state of charge can be improved by estimating and correcting the state of charge according to the voltage data of each battery cell, and therefore, the balancing effect is good. In the range of 10% to 40%, the state of charge range may be preferably 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 due to the polarization characteristics of the lithium iron phosphate material and the difference between the battery cells in the lithium iron phosphate battery pack, the voltage drops to the platform region, the pressure difference is small, and the equalization is not easily triggered or the implementation effect after the equalization is triggered is not good. At a state of charge of 40% -90% of the platform area, the state of charge has almost no correlation with voltage in the area, and equalization cannot be triggered or misequalization can be caused. When the charge state is 0-10%, the cell in the lithium iron phosphate battery pack cannot be used as a balancing interval in order to prevent the cell from being overdischarged, so that the cell in the lithium iron phosphate battery pack needs to be balanced by adopting a low-end balancing method when the charge state of the lithium iron phosphate battery pack is 10-40%.
And S204, discharging the battery unit of which the difference value between the voltage data in the lithium iron phosphate battery pack and the minimum voltage value is greater than or equal to the voltage threshold value.
Specifically, in the embodiment of the present invention, when it is determined that the state of charge of the lithium iron phosphate battery pack is 10% to 40%, and a battery cell in which a difference between voltage data in the lithium iron phosphate battery pack and a minimum voltage value is greater than or equal to a voltage threshold exists, discharge is performed on the battery cell in which the difference between the voltage data in the lithium iron phosphate battery pack and the minimum voltage value is greater than or equal to the voltage threshold, so that, through discharge, after a battery cell in the lithium iron phosphate battery pack with a higher original voltage is discharged, the voltage of the battery cell with the voltage data that is the smallest in the lithium iron phosphate battery pack tends to be consistent, balance of the lithium iron phosphate battery pack is achieved, and imbalance in the degree of charge of the lithium iron phosphate.
S205, judging whether the voltage data of the battery unit discharged in the iron-based battery pack reaches a specified condition, if so, executing S206, and if not, executing S201.
Specifically, in the embodiment of the present invention, after the discharging is performed on the battery unit whose difference between the voltage data in the lithium iron phosphate battery pack and the minimum voltage value is greater than or equal to the voltage threshold, it is further required to determine whether the voltage data of the battery unit that is discharged in the lithium iron phosphate battery pack reaches a specified condition, and if it is determined that the voltage data of the battery unit that is discharged in the lithium iron phosphate battery pack reaches the specified condition, S206 is performed. On the contrary, if it is determined that the voltage data of the discharged battery cells in the iron-based battery pack does not meet the specified condition, S201 is performed, that is, the operations of detecting, estimating, determining, and balancing are performed again.
In a specific implementation process, the specified condition may include: and the voltage data of the discharged battery unit in the iron-based battery pack is consistent with the minimum voltage value.
And S206, stopping discharging the battery unit of which the difference value between the voltage data in the iron-based lithium-iron battery pack and the minimum voltage value is greater than or equal to the voltage threshold value.
Specifically, in the embodiment of the present invention, after the discharge is performed on the battery cell of which the difference between the voltage data in the lithium iron phosphate battery pack and the minimum voltage value is greater than or equal to the voltage threshold, when it is determined that the voltage data of the battery cell discharged in the lithium iron phosphate battery pack reaches a specified condition, the discharge of the battery cell of which the difference between the voltage data in the lithium iron phosphate battery pack and the minimum voltage value is greater than or equal to the voltage threshold is stopped, and after the discharge of the battery cell is stopped, the charge balance of the lithium iron phosphate battery pack is achieved.
And S207, discharging is not performed on the battery unit in the lithium iron phosphate battery pack, and the process is ended.
EXAMPLE III
Please refer to fig. 4, which is a flowchart illustrating a third embodiment of a battery pack balancing method according to an embodiment of the present invention. As shown, the method comprises the following steps:
s401, fully charging the lithium iron phosphate battery pack, and then discharging until the charge state of the lithium iron phosphate battery pack is 20% -25%.
S402, in the sleep mode, detecting and recording voltage data of 100 battery units connected in series in the lithium iron phosphate battery pack, and recording the voltage data as UNN is equal to 1, 2, 3.
And S403, calculating the difference value between the voltage data of each battery unit in the lithium iron phosphate battery pack and the minimum voltage value.
And S404, discharging the battery unit with the difference value between the voltage data and the minimum voltage value of the lithium iron phosphate battery pack larger than 8 mV.
And S405, re-executing the low-end balance of the lithium iron phosphate battery pack at intervals, namely executing S401 to S405 until the voltage data of the battery unit with higher voltage data is consistent with the minimum voltage value, and finishing the balance of the lithium iron phosphate battery pack.
The embodiment of the invention further provides an embodiment of a device for realizing the steps and the method in the embodiment of the method.
Please refer to fig. 5, which is a functional block diagram of a battery management system according to a first embodiment of the present invention. As shown, the battery management system includes:
the detection module 51 is used for detecting voltage data of each battery unit in the lithium iron phosphate battery pack;
the electric quantity estimation module 52 is used for acquiring the charge state of the lithium iron phosphate battery pack according to the voltage data of each battery unit;
an equalizing module 53, configured to obtain a minimum voltage value in the voltage data; judging whether the state of charge is 10% -40%, and comparing the difference between the voltage data of each battery unit in the lithium iron phosphate battery pack and the minimum voltage value with a preset voltage threshold value; and if the state of charge is judged to be 10% -40%, and a battery unit with a difference value between the voltage data and the minimum voltage value larger than or equal to the voltage threshold value exists, discharging the battery unit with the difference value between the voltage data and the minimum voltage value larger than or equal to the voltage threshold value in the lithium iron phosphate battery pack.
Optionally, the equalizing module 53 is further configured to:
and when the voltage data of the discharged battery unit in the iron-based physical battery pack reaches a specified condition, stopping discharging the battery unit of which the difference value between the voltage data in the iron-based physical battery pack and the minimum voltage value is greater than or equal to the voltage threshold value.
Preferably, the specified conditions include: and the voltage data of the discharged battery unit in the iron-based battery pack is consistent with the minimum voltage value.
Preferably, the detection module 51 is specifically configured to: detecting voltage data of each battery unit in the lithium iron phosphate battery pack in a sleep mode; wherein the sleep mode includes no input energy or output energy of the lithium iron phosphate battery pack.
Preferably, each battery unit includes one battery cell, or each battery unit includes at least two battery cells connected in parallel.
Preferably, each battery cell in the lithium iron phosphate battery pack comprises a lithium ion battery cell in which the solid content of lithium iron phosphate in the cathode active material is greater than or equal to 90%.
Since each unit in the embodiment can execute the method shown in fig. 1, fig. 2 or fig. 4, reference may be made to the related description of fig. 1, fig. 2 or fig. 4 for a part of the embodiment that is not described in detail.
Please refer to fig. 6, which is a functional block diagram of a battery management system according to a second embodiment of the present invention. As shown, the battery management system may further include: and the charging module 54 is used for fully charging the lithium iron phosphate battery pack and then discharging until the charge state of the lithium iron phosphate battery pack is 10% -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 battery management system 71 described above.
It is understood that the lithium iron phosphate battery pack includes lithium ion battery cells in which the solid content of lithium iron phosphate in the cathode active material is greater than or equal to 90%.
The technical scheme of the embodiment of the invention has the following beneficial effects:
in the technical scheme provided by the embodiment of the invention, whether the balanced starting condition is met is judged according to the charge state of the lithium iron phosphate battery pack and the difference value between the voltage data and the minimum voltage value of each battery unit in the lithium iron phosphate battery pack, if the balanced starting condition is met, namely the charge state is at the low end (the charge state is between 10 and 40 percent), and the battery units with the difference value between the voltage data and the minimum voltage value being more than or equal to the voltage threshold value exist, the battery units meeting the balanced starting condition are discharged, so that the voltage of the battery units with higher voltage data in the lithium iron phosphate battery pack is consistent with the minimum voltage value, the charge imbalance among the battery units is reduced, the charge equalization among the battery units is effectively realized, and the problems of power capacity and available energy exertion of the lithium iron phosphate battery system caused by the larger charge imbalance are solved, the service life of the lithium iron phosphate battery pack is prolonged. And the balance efficiency of the lithium iron phosphate battery pack can be effectively improved through low-end balance.
In addition, compared with the starting equalization in other charge states (the charge state is 40% -100%) in the prior art, the technical scheme provided by the embodiment of the invention has better charge equalization effect, can prevent error equalization, improves the equalization effect, reduces the charge imbalance degree among the battery units to the maximum extent, and improves the inconsistency among the battery units, thereby prolonging the service life of the lithium iron phosphate battery pack.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the embodiments provided in the present invention, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and there may be other divisions in actual implementation, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.
The integrated unit implemented in the form of a software functional unit may be stored in a computer readable storage medium. The software functional unit is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) or a Processor (Processor) to execute some steps of the methods according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (13)
1. A method for balancing a battery pack, comprising:
detecting voltage data of each battery unit in the lithium iron phosphate battery pack, and acquiring the charge state of the lithium iron phosphate battery pack according to the voltage data of each battery unit;
acquiring a minimum voltage value in the voltage data;
judging whether the state of charge is 10% -40%, and comparing the difference between the voltage data of each battery unit in the lithium iron phosphate battery pack and the minimum voltage value with a preset voltage threshold value respectively;
and if the state of charge is judged to be 10% -40%, and a battery unit with the difference value between the voltage data and the minimum voltage value larger than or equal to the voltage threshold value exists, discharging the battery unit with the difference value between the voltage data and the minimum voltage value larger than or equal to the voltage threshold value in the lithium iron phosphate battery pack.
2. The battery pack equalization method of claim 1, further comprising:
and when the voltage data of the discharged battery units in the lithium iron phosphate battery pack reaches a specified condition, stopping discharging the battery units of which the difference value between the voltage data in the lithium iron phosphate battery pack and the minimum voltage value is greater than or equal to the voltage threshold value.
3. The battery pack balancing method according to claim 2, wherein the specified condition includes: and the voltage data of the discharged battery unit in the lithium iron phosphate battery pack is consistent with the minimum voltage value.
4. The battery pack balancing method according to claim 1, wherein detecting voltage data of each battery cell in the lithium iron phosphate battery pack comprises:
detecting voltage data of each battery unit in the lithium iron phosphate battery pack in a sleep mode;
wherein the sleep mode includes no input energy or output energy of the lithium iron phosphate battery pack.
5. The battery pack balancing method according to any one of claims 1 to 4, wherein each battery unit comprises one battery cell, or each battery unit comprises at least two battery cells connected in parallel.
6. The battery pack balancing method according to claim 5, wherein each battery cell in the lithium iron phosphate battery pack comprises a lithium ion battery cell in which the solid content of lithium iron phosphate in the cathode active material is greater than or equal to 90%.
7. A battery management system, characterized in that the battery management system comprises:
the detection module is used for detecting voltage data of each battery unit in the lithium iron phosphate battery pack;
the electric quantity estimation module is used for acquiring the charge state of the lithium iron phosphate battery pack according to the voltage data of each battery unit;
the balancing module is used for acquiring a minimum voltage value in the voltage data; judging whether the state of charge is 10% -40%, and comparing the difference between the voltage data of each battery unit in the lithium iron phosphate battery pack and the minimum voltage value with a preset voltage threshold value; and if the state of charge is judged to be 10% -40%, and a battery unit with a difference value between the voltage data and the minimum voltage value larger than or equal to the voltage threshold value exists, discharging the battery unit with the difference value between the voltage data and the minimum voltage value larger than or equal to the voltage threshold value in the lithium iron phosphate battery pack.
8. The battery management system of claim 7, wherein the equalization module is further configured to:
and when the voltage data of the discharged battery units in the lithium iron phosphate battery pack reaches a specified condition, stopping discharging the battery units of which the difference value between the voltage data in the lithium iron phosphate battery pack and the minimum voltage value is greater than or equal to the voltage threshold value.
9. The battery management system according to claim 8, wherein the specified condition includes: and the voltage data of the discharged battery unit in the lithium iron phosphate battery pack is consistent with the minimum voltage value.
10. The battery management system of claim 7, wherein the detection module is specifically configured to: detecting voltage data of each battery unit in the lithium iron phosphate battery pack in a sleep mode;
wherein the sleep mode includes no input energy or output energy of the lithium iron phosphate battery pack.
11. The battery management system according to any one of claims 7 to 10, wherein each battery unit comprises one battery cell, or wherein each battery unit comprises at least two battery cells connected in parallel.
12. A battery system comprising a lithium iron phosphate battery pack and a battery management system according to any one of claims 7 to 11.
13. The battery system of claim 12, wherein the lithium iron phosphate battery pack comprises lithium ion battery cells having a solid content of lithium iron phosphate in the cathode active material of greater than or equal to 90%.
Applications Claiming Priority (1)
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| PCT/CN2016/074116 WO2017139967A1 (en) | 2016-02-19 | 2016-02-19 | Battery pack balancing method, battery management system and battery system |
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| CN109995102B (en) * | 2019-03-01 | 2022-04-01 | 中国第一汽车股份有限公司 | Power battery equalization system for electric automobile and control method |
| CN111490304B (en) * | 2020-05-18 | 2021-09-07 | 重庆金康动力新能源有限公司 | Battery equalization enabling method and device, storage medium and battery pack |
| CN113212207B (en) * | 2021-05-21 | 2022-06-28 | 度普(苏州)新能源科技有限公司 | Single cell balancing method and device for charging pile |
| CN113839439A (en) * | 2021-08-27 | 2021-12-24 | 北京机械设备研究所 | Full-time battery pack balance control method and device and storage medium |
| CN115603351B (en) * | 2022-12-13 | 2023-04-07 | 麦田能源有限公司 | Energy storage system processing method and device, processor and electronic equipment |
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| CN108780927A (en) | 2018-11-09 |
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