CN109494850B - Battery pack balancing method, device and system - Google Patents
Battery pack balancing method, device and system Download PDFInfo
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- CN109494850B CN109494850B CN201910016201.3A CN201910016201A CN109494850B CN 109494850 B CN109494850 B CN 109494850B CN 201910016201 A CN201910016201 A CN 201910016201A CN 109494850 B CN109494850 B CN 109494850B
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- 238000000034 method Methods 0.000 title claims abstract description 212
- 230000008569 process Effects 0.000 claims abstract description 162
- 238000007599 discharging Methods 0.000 claims abstract description 34
- 239000000178 monomer Substances 0.000 claims description 4
- 210000004027 cell Anatomy 0.000 claims 2
- 210000004460 N cell Anatomy 0.000 claims 1
- 238000004590 computer program Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 125000004122 cyclic group Chemical group 0.000 description 2
- 230000017525 heat dissipation Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
- H02J7/0014—Circuits for equalisation of charge between batteries
Abstract
The invention discloses a battery pack balancing method, device and system, and relates to the field of power batteries. The battery pack can be divided into a plurality of sub battery packs, in the charging process of the battery pack, when the battery pack is detected to meet the equalization condition, all or part of the N single batteries to be equalized can be equalized in at least one of the charging process of the battery pack, the discharging process after the charging of the battery pack is completed and the next charging process of the battery pack, and the number of the equalized single batteries in each sub battery pack is smaller than or equal to a number threshold. Therefore, in the balancing process of the battery pack, the situation that the balancing loop is burnt due to excessive balanced single batteries can be avoided. In addition, the method provided by the invention can balance the battery pack in the whole charging process and the discharging process of the battery pack, thereby effectively improving the balancing efficiency.
Description
Technical Field
The invention relates to the field of power batteries, in particular to a battery pack balancing method, a battery pack balancing device and a battery pack balancing system.
Background
During the use of the electric automobile, the battery pack is required to provide energy for the electric automobile. The battery pack generally comprises a plurality of single batteries, but the single batteries produced in the same batch have different performance parameters such as internal resistance, capacity, self-discharge rate and the like, and the capacity difference among the single batteries is more and more obvious along with the increase of the number of times of cyclic charge and discharge, so that the service life of the battery pack is seriously influenced. Therefore, the battery pack needs to be balanced during charging and discharging to reduce the capacity imbalance of the battery pack caused by the capacity difference of each unit cell.
In the related art, in order to equalize the capacities of the single batteries in the battery pack, each single battery in the battery pack may be connected in series with a resistor and a switch. When the switch is turned on, part of electric energy of the single batteries can be converted into heat energy of the resistor, so that the capacity of each single battery in the battery pack is balanced.
However, in the equalizing process, each resistor is heated up due to heat dissipation, so that the resistance value of the resistor is reduced, the equalizing current of the equalizing loop is increased, and the equalizing loop is burnt out due to overlarge current.
Disclosure of Invention
The embodiment of the invention provides a battery pack balancing method, a battery pack balancing device and a battery pack balancing system, which can solve the problem of burnout of a balancing loop caused by overhigh balancing current in the related art. The technical scheme is as follows:
On one hand, a battery pack balancing method is provided, the battery pack comprises M single batteries, the M single batteries are divided into a plurality of sub battery packs, each sub battery pack comprises a plurality of single batteries connected in series, wherein M is a positive integer greater than 1; the method comprises the following steps:
in the charging process of the battery pack, judging whether the battery pack meets an equalization condition or not according to the voltage difference of the M single batteries;
when the battery pack meets an equalization condition, determining N single batteries to be equalized from M single batteries included in the battery pack, wherein the voltage of each single battery to be equalized is greater than that of the rest single batteries, and N is a positive integer less than or equal to M/2;
in the balancing process, all or part of the N single batteries to be balanced are balanced, and the number of the balanced single batteries in each sub-battery pack is smaller than or equal to a number threshold, wherein the balancing process comprises at least one of the current charging process of the battery pack, the discharging process of the battery pack after the current charging process and the next charging process of the battery pack.
Optionally, in the charging process of the battery pack, determining whether the battery pack meets an equalization condition according to the voltage difference between the M single batteries includes:
acquiring the voltage of each single battery in the charging process of the battery pack;
when the maximum value of the voltages of the M single batteries is larger than a first voltage threshold value, determining the voltage difference of the M single batteries;
when the voltage difference is within a difference range, determining the capacity difference of the M single batteries;
when the capacity difference is larger than a capacity difference threshold value, determining that the battery pack meets the balance condition;
determining that the battery pack does not satisfy the equalization condition when the capacity difference is less than or equal to a capacity difference threshold.
Optionally, after determining whether the battery pack satisfies an equalization condition according to the voltage difference between the M single batteries, the method further includes:
when the battery pack meets the equalization condition, setting the equalization identifier as a first identifier;
when the battery pack does not meet the equalization condition, setting the equalization identifier as a second identifier;
in the balancing process, balancing all or part of the N single batteries to be balanced includes:
Detecting whether the equalization mark is the first mark;
and when the balancing identification of the battery pack is the first identification, balancing all or part of the to-be-balanced single batteries in the N to-be-balanced single batteries.
Optionally, after determining N single batteries to be equalized from M single batteries included in the battery pack, the method further includes:
recording the battery label of each monomer battery to be balanced in the N monomer batteries to be balanced;
in the balancing process, balancing all or part of the N single batteries to be balanced includes:
and in the balancing process, balancing all or part of the single batteries to be balanced according to the recorded battery labels of the single batteries to be balanced.
Optionally, the balancing process is a current charging process of the battery pack and/or a next charging process of the battery pack, and in the process of balancing all or part of the N single batteries to be balanced, the method further includes:
when the voltage of each single battery in the M single batteries is larger than the first voltage threshold value, stopping balancing the single batteries to be balanced;
And setting the balancing identification as a second identification, and clearing the recorded battery labels of the single batteries to be balanced.
Optionally, the equalizing process is a discharging process after the battery pack is charged this time, and the equalizing process is performed on all or part of the N single batteries to be equalized, and includes:
when the minimum value of the voltages of the M single batteries is larger than a second voltage threshold value, balancing all or part of the N single batteries to be balanced;
the method further comprises the following steps:
and when the minimum value of the voltages of the M single batteries is smaller than a second voltage threshold value, stopping balancing the single batteries to be balanced.
Optionally, after determining whether the battery pack satisfies the equalization condition, the method further includes:
and when the battery pack does not meet the equalization condition, clearing the recorded battery labels of the single batteries to be equalized.
In another aspect, a battery pack balancing apparatus is provided, where the battery pack includes M single batteries, the M single batteries are divided into a plurality of sub battery packs, each sub battery pack includes a plurality of single batteries connected in series, where M is a positive integer greater than 1; the device comprises:
The judging module is used for judging whether the battery pack meets an equalization condition or not according to the voltage difference of the M single batteries in the charging process of the battery pack;
the determining module is used for determining N single batteries to be balanced from M single batteries included in the battery pack when the battery pack meets a balancing condition, wherein the voltage of each single battery to be balanced is greater than that of the rest single batteries, and N is a positive integer less than or equal to M/2;
and the equalizing module is used for equalizing all or part of the N single batteries to be equalized in an equalizing process, wherein the number of the equalized single batteries in each sub-battery pack is less than or equal to a number threshold, and the equalizing process comprises at least one of the current charging process of the battery pack, the discharging process of the battery pack after the charging process is completed and the next charging process of the battery pack.
Optionally, the determining module includes:
the acquisition submodule is used for acquiring the voltage of each single battery in the charging process of the battery pack;
the first determining submodule is used for determining the voltage difference of the M single batteries when the maximum value of the voltage of the M single batteries is larger than a first voltage threshold value;
The second determining submodule is used for determining the capacity difference of the M single batteries when the voltage difference is within a difference range;
a third determining submodule, configured to determine that the battery pack satisfies the balancing condition when the capacity difference is greater than a capacity difference threshold; determining that the battery pack does not satisfy the equalization condition when the capacity difference is less than or equal to a capacity difference threshold.
Optionally, the apparatus further comprises:
the setting module is used for setting the equalization identifier as a first identifier when the battery pack meets the equalization condition after the judging module judges whether the battery pack meets the equalization condition according to the voltage difference of the M single batteries; when the battery pack does not meet the equalization condition, setting the equalization identifier as a second identifier;
the equalization module is configured to:
detecting whether the equalization mark is the first mark;
and when the balancing identification of the battery pack is the first identification, balancing all or part of the to-be-balanced single batteries in the N to-be-balanced single batteries.
Optionally, the apparatus further comprises:
the recording module is used for recording a battery label of each single battery to be balanced in the N single batteries to be balanced after the determining module determines the N single batteries to be balanced from the M single batteries included in the battery pack;
The equalization module is configured to:
and in the balancing process, balancing all or part of the single batteries to be balanced according to the recorded battery labels of the single batteries to be balanced.
Optionally, the balancing process is a current charging process of the battery pack and/or a next charging process of the battery pack, and the balancing module is further configured to:
when the voltage of each single battery in the M single batteries is larger than the first voltage threshold value, stopping balancing the single batteries to be balanced;
the setting module is further configured to set the balancing identifier as a second identifier, and clear the recorded battery label of the single battery to be balanced.
Optionally, the balancing process is a discharging process after the charging of the battery pack is completed this time, and the balancing module is configured to:
when the minimum value of the voltages of the M single batteries is larger than a second voltage threshold value, balancing all or part of the N single batteries to be balanced;
and when the minimum value of the voltages of the M single batteries is smaller than a second voltage threshold value, stopping balancing the single batteries to be balanced.
Optionally, the recording module is further configured to: and after the judging module judges whether the battery pack meets the balancing condition, when the battery pack does not meet the balancing condition, clearing the recorded battery labels of the single batteries to be balanced.
In yet another aspect, a battery pack balancing apparatus is provided, the apparatus including: a processing component, a memory, and a computer program stored on and executable on the memory, the processing component, when executing the computer program, implementing the battery balancing method as described in the above aspect.
In yet another aspect, a computer-readable storage medium having instructions stored therein, which when run on a computer, cause the computer to perform the battery balancing method according to the above aspect.
In yet another aspect, a battery pack balancing system is provided, the system comprising: the battery pack comprises M single batteries, the M single batteries correspond to the M resistors one by one and the M switches one by one, M is a positive integer larger than 1, and M is a positive integer larger than 1;
each resistor is connected with one corresponding switch in series, and the resistor and the switch which are connected in series are connected with one corresponding single battery in parallel to form a balance loop;
Each switch is connected with the battery pack balancing device, and the battery pack balancing device is used for controlling the on or off of each switch.
Optionally, the battery pack balancing device, the M resistors, and the M switches are all integrated on a circuit board, and the system further includes: a temperature sensor integrated on the circuit board;
the temperature sensor is used for detecting the temperature of the circuit board;
the battery pack balancing device is connected with the temperature sensor and is also used for controlling the on and off of each switch according to the temperature.
The technical scheme provided by the invention has the beneficial effects that at least:
the invention provides a battery pack balancing method, device and system. In the battery pack charging process, when it is detected that the battery pack meets the equalization condition, all or part of the N single batteries to be equalized can be equalized in at least one of the charging process of the battery pack, the discharging process after the battery pack is charged, and the next charging process of the battery pack, and the number of the equalized single batteries included in each sub battery pack is less than or equal to the number threshold. Therefore, in the balancing process of the battery pack, the situation that the temperature is too high and the balancing loop is burnt due to too many balanced single batteries can be avoided. In addition, the method provided by the invention can balance the battery pack in the whole charging process and the discharging process of the battery pack, thereby prolonging the balancing time and effectively improving the balancing efficiency.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced 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 creative efforts.
Fig. 1 is a flowchart of a battery pack balancing method according to an embodiment of the present invention;
fig. 2 is a flowchart of another battery pack balancing method according to an embodiment of the present invention;
fig. 3 is a flowchart of a method for determining whether a battery pack satisfies an equalization condition according to an embodiment of the present invention;
fig. 4 is a flowchart of a battery pack balancing method in a charging process according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a battery pack balancing apparatus according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a determining module according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of another battery pack balancing apparatus according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
At present, with the rapid development of battery technology of electric vehicles and the popularization of charging piles, electric vehicles have entered into ordinary families. However, the energy storage of the battery of the electric vehicle is always the bottleneck of the development of the electric vehicle. Due to the limitation of the production process, the performance parameters such as internal resistance, capacity and self-discharge rate of the single batteries produced in the same batch are different, and the capacity difference between the single batteries is more and more obvious along with the increase of the number of times of cyclic charge and discharge, so that the service life of the battery pack is seriously influenced. Therefore, the battery pack needs to be managed in a balanced manner so that the capacities of the unit batteries of the battery pack are consistent.
In the related art, the battery pack is usually equalized by passive equalization. Each cell in the battery pack is typically connected in parallel with a resistor (e.g., a power resistor) and a switch, and the cell, the resistor, and the switch may form an equalization loop. When the switch is turned on, part of electric energy of the single battery can be converted into heat energy of the resistor, so that the capacity of each single battery in the battery pack is kept consistent.
However, in the equalizing process, the resistor is heated due to heat dissipation, so that the resistance value of the resistor is reduced, the equalizing current of the equalizing loop is increased, and the equalizing loop is burnt due to overlarge current. And the temperature is proportional to the number of the unit cells equalized at one time. That is, the more the number of the unit cells equalized at one time, the higher the temperature will be. Therefore, the balancing method in the related art has the advantages of less number of single batteries balanced at one time and lower balancing efficiency.
In addition, when balancing the battery pack in the related art, the balancing is performed only in the last charging stage of the battery pack (after the battery pack has charged about 95%), and the balancing time is short, which results in low balancing efficiency.
The embodiment of the invention provides a battery pack balancing method which can be applied to a battery pack balancing device. The method can solve the problem of burning out of the equalizing loop caused by overhigh equalizing current in the related technology and the problem of lower equalizing efficiency in the related technology. Moreover, the battery pack balancing method provided by the embodiment of the invention can be used for a battery pack with a large number of single batteries (for example, the number of the single batteries can be greater than or equal to 150), and the battery pack can be used for providing energy for a large-sized electric vehicle.
In an embodiment of the present invention, the battery pack may include M single batteries, the M single batteries may be divided into a plurality of sub-battery packs, and each sub-battery pack may include a plurality of single batteries connected in series, that is, a plurality of single batteries included in each sub-battery pack are located in the same region. Wherein M is a positive integer greater than 1. Illustratively, M may be greater than or equal to 150.
Optionally, M single batteries may be grouped by using a preset number of single batteries as a group, and the remaining single batteries may be divided into a group, so as to divide the M single batteries into a plurality of sub-battery groups. For example, if M is 150 and the preset value is 60, the 150 single batteries may be divided into 3 sub-battery packs, where the number of the single batteries included in the 3 sub-battery packs is sequentially: 60, 60 and 30.
Referring to fig. 1, the battery pack balancing method may include:
Wherein, the voltage difference of the M single batteries is as follows: the difference between the voltage of the highest cell and the voltage of the lowest cell among the M cells is referred to. The equalization conditions may be: the voltage difference of the M single batteries is within the difference range.
And 102, when the battery pack meets the balancing condition, determining N single batteries to be balanced from M single batteries included in the battery pack.
The voltage of each single battery to be balanced is larger than that of the rest single batteries, and N is a positive integer smaller than or equal to M/2. That is, the N unit cells to be equalized are N unit cells with higher voltage among the M unit cells. Optionally, the N single batteries to be equalized may be distributed in different sub-battery packs.
For example, if M is 150 and N is M/2, the battery pack balancing apparatus may determine, after detecting that the battery pack satisfies the balancing condition, the 75 single batteries with the highest voltage among the 150 single batteries included in the battery pack as the single batteries to be balanced.
And 103, balancing all or part of the N single batteries to be balanced in the balancing process.
The equalization process may include at least one of a charging process of the battery pack at this time, a discharging process after the charging of the battery pack at this time is completed, and a next charging process of the battery pack.
And the number of the equalized single batteries in each sub-battery pack is less than or equal to a number threshold value. The number threshold may be one-half of the maximum value of the number of unit batteries included in each sub-battery group. The equalized single battery is determined by the battery pack equalizing device from the single batteries to be equalized.
Because the number of the balanced single batteries in each sub-battery pack is less than or equal to the number threshold, when the battery pack is balanced, the total heat emitted by the resistor connected with the balanced single batteries in each sub-battery pack is not too high, so that the current of a balancing loop caused by too high temperature can be avoided being too high, the safety of the balancing loop can be ensured, and the balancing loop is prevented from being burnt.
And under the condition that the equalizing loop in each sub-battery pack is not burnt, the battery pack equalizing device can equalize each sub-battery pack, namely, the single batteries to be equalized in each region can be equalized. Therefore, the number of the balanced single batteries can be effectively increased, and the balancing efficiency of the battery pack is improved.
In summary, the embodiments of the present invention provide a battery pack balancing method, where the battery pack may be divided into a plurality of sub battery packs. In the battery pack charging process, when it is detected that the battery pack meets the equalization condition, all or part of the N single batteries to be equalized can be equalized in at least one of the charging process of the battery pack, the discharging process after the battery pack is charged, and the next charging process of the battery pack, and the number of the equalized single batteries included in each sub battery pack is less than or equal to the number threshold. Therefore, in the balancing process of the battery pack, the situation that the temperature is too high and the balancing loop is burnt due to too many balanced single batteries can be avoided. In addition, the method provided by the embodiment of the invention can balance the battery pack in the whole charging process and the discharging process of the battery pack, thereby prolonging the balancing time and effectively improving the balancing efficiency.
Fig. 2 is a flowchart of another battery pack balancing method according to an embodiment of the present invention. Referring to fig. 2, the method may include:
In the embodiment of the present invention, the battery pack balancing apparatus may detect whether the balancing identifier of the battery pack is the first identifier when the battery pack starts to be charged. The equalization flag may be used to indicate whether the battery pack needs equalization at the beginning of charging. And when the equalization flag is a first flag (e.g. 1), it may indicate that the battery pack needs equalization at the beginning of charging; when the equalization flag is the second flag (e.g., 0), it may indicate that the battery pack does not need equalization at the start of charging. The equalization identifier of the battery pack may be obtained by the battery pack equalization device in the last charging process and stored in the memory, and the initial identifier of the equalization identifier may be the second identifier.
For example, if the battery pack balancing apparatus detects that the balancing flag of the battery pack is 1 during the charging process of the battery pack, it may be determined that the battery pack needs to be balanced. If the battery pack balancing device detects that the balancing identifier is 0, it can be determined that the battery pack does not need to be balanced.
When detecting that the balancing identifier of the battery pack is the first identifier, the battery pack balancing apparatus may perform step 202; when it is detected that the equalization flag of the battery pack is not the first flag, the battery pack may continue to be charged, and the battery pack equalization apparatus may perform step 203.
And step 202, balancing all or part of the N single batteries to be balanced according to the recorded battery labels. Step 203 is performed.
In the embodiment of the present invention, the battery label may be a battery label of a single battery to be equalized, which is obtained and stored in the memory when the battery pack equalizing device determines that the battery pack satisfies the equalization condition in the last charging process of the battery pack. And the battery labels of the single batteries to be equalized in each sub-battery pack can be stored in the same storage area of the memory. Alternatively, the memory may be a charged erasable programmable read-only memory (EEPROM).
When detecting that the balancing identifier of the battery pack is the first identifier, the battery pack balancing device may first read the battery label of the to-be-balanced battery cell in each sub battery pack from the memory. Subsequently, the number of the single batteries to be equalized included in each sub-battery group may be determined. If the number is smaller than or equal to the number threshold, the single batteries to be equalized in each sub-battery pack can be equalized directly according to the recorded battery label of each single battery to be equalized, that is, all the single batteries to be equalized in the N single batteries to be equalized are equalized, so that the capacities of the M single batteries in the battery pack are kept consistent.
If the number is greater than the number threshold, balancing the single batteries to be balanced in the number threshold only according to the battery labels of the single batteries to be balanced in the number threshold in the sub-battery pack, that is, balancing part of the single batteries to be balanced in the N single batteries to be balanced, so that the capacities of the M single batteries in the battery pack are kept consistent. Alternatively, the number threshold may be 1/2 of the maximum number of the unit cells included in each sub-battery group. The battery pack balancing device can randomly select the single batteries to be balanced with the number threshold.
Therefore, the number of the balanced single batteries in each sub-battery pack can be smaller than or equal to the number threshold, and further the temperature rise of a balancing loop, the increase of the balancing current and the burnout of the balancing loop caused by the large number of the balanced single batteries can be avoided in the balancing process of the battery pack.
When the battery pack is balanced, the capacities of the single batteries in the battery pack can be kept consistent by reducing the capacity of the single battery with higher capacity, so that the voltages of the single batteries can be kept consistent.
For example, assuming that M is 150 and N is 75, the battery pack includes 3 sub-battery packs, and the number of the single batteries included in each sub-battery pack is sequentially: 60, 60 and 30. The number threshold is 30. And, the group battery balancing unit determines the number of the to-be-balanced battery cells included in the 3 sub-battery packs according to the label of the to-be-balanced battery cell recorded in the memory: 40, 20 and 15. Because the number of waiting to equalize the battery cell that first sub battery group includes is greater than 30, and the number of waiting to equalize the battery cell that other two sub battery groups include all is less than 30, consequently when equalizing the group battery, can only wait to equalize the battery cell to this 75 part of waiting to equalize in the battery cell, and the number of the battery cell that is equalized in 3 sub battery groups is in proper order: 30, 20 and 15.
If the battery pack balancing device determines that the number of the single batteries to be balanced in the 3 sub battery packs is sequentially as follows according to the marks of the single batteries to be balanced recorded in the memory: 28, 28 and 19, since each sub-battery pack includes less than 30 number of single batteries to be equalized, all the 75 single batteries to be equalized can be equalized when the battery pack is equalized.
And 203, judging whether the battery pack meets the balance condition or not according to the voltage difference of the M single batteries.
When the battery pack satisfies the balancing condition, the battery pack balancing device may perform step 204 and step 206; when the battery pack does not satisfy the balancing condition, the battery pack balancing apparatus may perform step 205.
In the embodiment of the present invention, no matter whether the balancing identifier is the second identifier or the first identifier, the battery pack balancing apparatus may re-determine whether the battery pack satisfies the balancing condition according to the voltage difference between the M single batteries at the last charging stage of the battery pack (after the battery pack charging capacity is about 95%).
Referring to fig. 3, the process of determining whether the battery pack satisfies the equalization condition according to the voltage difference between the M single batteries by the battery pack equalization apparatus may include:
In an embodiment of the present invention, the battery pack balancing apparatus may be connected to a Battery Management System (BMS), and the BMS may detect voltages of M unit batteries in the battery pack in real time and transmit the detected voltages to the battery pack balancing apparatus.
In the embodiment of the invention, when the battery pack meets the battery pack equalization judgment condition, whether the battery pack meets the equalization condition can be judged. The battery pack balancing judgment condition is as follows: the battery pack pressure difference is large and the voltage change of each single battery in the battery pack is gentle. In the charging process of the battery pack, the voltage of each single battery in the battery pack rises more stably in the early stage of charging the battery pack (the charging capacity of the battery pack is about 20 to 95 percent), the voltage at the moment is called the platform voltage of the single battery, and the voltage difference of the battery pack is smaller, so that the battery pack does not meet the equilibrium judgment condition of the battery pack. In the discharging process of the battery pack, the current output of the battery pack is large, the voltage change of the single batteries of the battery pack is severe, and the balance judgment condition of the battery pack is not met. Therefore, whether the battery pack meets the equalization condition cannot be accurately judged in the early stage of charging and the discharging period of the battery pack. At the end of the battery pack charging (after the battery pack is charged by about 95%), the voltage difference of the battery pack is large, and the voltage of each single battery does not change drastically. In the period, the battery pack can meet the battery pack balance judgment condition, and whether the battery pack meets the balance condition can be accurately judged.
In the charging process of the battery pack, when the maximum value of the voltages of the M single batteries is greater than a first voltage threshold value, the battery pack can be determined to be in the final charging stage, and the battery pack meets the equalization judgment condition at the moment. Further, the battery pack balancing device may obtain a maximum value of the voltages of the M single batteries and a minimum value of the voltages of the M single batteries, and determine a difference between the maximum value and the minimum value as a voltage difference of the M single batteries.
Alternatively, the first voltage threshold may be determined according to the type of the unit battery included in the battery pack. For example, if the battery pack includes all the single batteries that are lithium iron phosphate batteries, the first voltage threshold may be 3550 millivolts (mv). When the battery pack includes unit batteries that are all ternary batteries, the first voltage threshold may be 4050 mv.
For example, assuming that the battery pack includes all the single batteries that are lithium iron phosphate batteries, the battery pack balancing apparatus may determine the voltage difference of the M single batteries when detecting that the maximum value of the voltages of the M single batteries is greater than 3550 mv.
Here, the capacity refers to a remaining charge (SOC) of each unit battery. The capacity difference refers to a difference value between the maximum capacity and the minimum capacity of the M single batteries of the battery pack. The capacity of each unit cell may be determined according to a voltage of the corresponding unit cell, and a state of charge-open circuit voltage (SOC-OCV) curve.
In the embodiment of the present invention, after determining the voltage difference between the M single batteries, the battery pack balancing apparatus may determine whether the voltage difference is within a preset difference range. When it is determined that the voltage difference is within the difference range, the battery pack balancing device may determine the maximum value and the minimum value of the capacities of the M unit batteries according to the maximum value and the minimum value of the voltages of the M unit batteries and the SOC-OCV curve, and determine the capacity difference of the M unit batteries according to the maximum value and the minimum value of the capacities.
In the embodiment of the present invention, when the voltage difference is smaller than the lower limit of the difference range, the battery pack balancing device may determine that the capacity consistency of each single battery in the battery pack is good, and it is not necessary to balance the battery pack, so that it is not necessary to perform subsequent operations, and the battery pack may continue to be charged normally. When the voltage difference is larger than the upper limit of the difference range, the battery pack balancing device can determine that the battery pack is damaged and needs to be replaced, so that subsequent operation does not need to be performed.
Alternatively, the difference range may be preset by an operator. For example, it is assumed that the difference value range may be 50mv to 300 mv. When the battery pack balancing device detects that the voltage difference is 260mv, the voltage difference is greater than 50mv and less than 300mv, and is within the range of the difference value, the capacity difference of the M single batteries can be further determined and determined. Assuming that the voltage difference detected by the battery pack balancing device is 30mv and is less than the lower limit of the difference range, namely 50mv, the battery pack balancing device can determine that the capacity consistency of the battery pack is better, the battery pack does not need to be balanced, subsequent operations are not executed any more, and the battery pack can continue to be charged normally. Assuming that the voltage difference detected by the battery pack balancing device is 350mv, the battery pack balancing device may determine that the battery pack is damaged and needs to be replaced, and no further operation is performed.
And step 2034, when the capacity difference is greater than the threshold value of the capacity difference, determining that the battery pack meets the equalization condition. Step 204 is performed.
When the battery pack balancing device determines the capacity difference of the M single batteries, the capacity difference may be compared with a capacity difference threshold value stored in advance, and when it is determined that the capacity difference is greater than the capacity difference threshold value, it may be determined that the battery pack satisfies the balancing condition.
For example, assuming that the capacity difference threshold is 1% and the capacity difference detected by the battery pack balancing device is 5%, since the capacity difference is greater than 1%, it may be determined that the battery pack satisfies the balancing condition.
When the battery pack balancing device compares the capacity difference with a pre-stored capacity difference threshold, and when the capacity difference is determined to be less than or equal to the capacity difference threshold, the battery pack is determined not to satisfy the balancing condition.
For example, assuming that the capacity difference threshold is 1% and the capacity difference of the battery pack determined by the battery pack balancing apparatus is 0.5%, it may be determined that the battery pack satisfies the unbalance condition since 0.5% < 1%.
In the embodiment of the present invention, if the battery pack balancing apparatus determines that the battery pack satisfies the balancing condition, the balancing flag may be set as the first flag, so as to indicate that the battery pack needs to be balanced in the balancing process.
By way of example, the first flag may be 1. That is, at the end of battery pack charging, if the battery pack balancing apparatus determines that the battery pack satisfies the balancing condition, the balancing flag may be set to 1.
And step 205, setting the balancing identifier as a second identifier, and clearing the recorded battery labels of the single batteries to be balanced.
In the embodiment of the present invention, if the battery pack balancing apparatus determines that the battery pack does not satisfy the balancing condition, the balancing identifier may be set as the second identifier, and the battery label of the previously recorded single battery to be balanced may be cleared. The recorded battery label of the single battery to be equalized can be the battery label of the single battery to be equalized determined according to the voltage of each single battery after the battery pack is judged to meet the equalization condition in the last charging process.
By setting the equalization flag as the second flag, it is possible to indicate that the battery pack does not need equalization during the charging process or the discharging process of the battery pack. By clearing the recorded battery labels of the single batteries to be equalized, confusion caused by the battery labels of the single batteries to be equalized, which are recorded subsequently, can be avoided.
For example, assuming that when the battery pack balancing apparatus detects that the battery pack does not satisfy the balancing condition, the balancing flag recorded in the memory is 1, and the battery labels of 75 single batteries to be balanced are recorded, the battery pack balancing apparatus may set the balancing flag to 0, and clear the recorded battery labels of 75 single batteries to be balanced.
It should be noted that, if the battery pack equalization apparatus is at the end of the nth charging of the battery pack, the equalization flag is set as the first flag. The battery pack balancing device will balance the battery pack at the beginning of the (n + 1) th charge of the battery pack. And if the battery pack does not reach the equalization judgment condition in the (n + 1) th charging process, the equalization mark is kept as the first mark. When the (n + 2) th charging of the battery pack starts, the battery pack balancing device still balances the battery pack. Therefore, if the balance judgment condition is not met in the charging process of the battery pack every time, the battery balancing device can continuously balance the battery pack in the charging process and the discharging process of the battery pack every time. This may lead to a deterioration in the uniformity of the battery pack and damage to the equalization circuit.
Therefore, in the embodiment of the present invention, when the battery pack balancing device detects that the maximum voltage values of M single batteries in the battery pack are all smaller than the first voltage threshold in M consecutive charging processes of the battery pack each time, it may be determined that the battery pack does not reach the balancing determination condition for M consecutive times, the balancing identifier is set as the second identifier, and at this time, the battery pack balancing device may set the balancing identifier as the second identifier and clear the recorded labels of the single batteries to be balanced. The damage of the equalizing loop in the subsequent charging process of the battery pack is avoided, and the reliability of the equalizing loop can be ensured. Where m may be a positive integer greater than 3, for example m may be equal to 4.
And step 206, determining N single batteries to be equalized from M single batteries included in the battery pack.
The voltage of each single battery to be equalized is greater than the voltage of the rest single batteries, N is a positive integer less than or equal to M/2, and N can be equal to M/2.
In the embodiment of the present invention, after the balancing flag is set as the first flag, the battery pack balancing apparatus may sort the voltages of the M single batteries in order from high to low, and determine the N batteries with higher voltages as the single batteries to be balanced.
For example, assuming that the number M of the single batteries included in the battery pack is 150, and N is equal to M/2, the battery pack balancing apparatus may determine, as the single battery to be balanced, the 75 single batteries with the highest voltage among the 150 single batteries included in the battery pack after detecting that the battery pack satisfies the balancing condition.
And step 207, recording the battery label of each single battery to be equalized in the N single batteries to be equalized.
In the embodiment of the invention, each single battery in the battery pack is provided with a corresponding battery label in advance. After the battery pack balancing device determines the battery to be balanced, the label of each single battery to be balanced can be obtained, and the label of each single battery to be balanced is stored in the memory.
For example, it is assumed that the battery pack balancing apparatus divides the battery pack into 3 sub-battery packs, and determines that there are 75 single batteries to be balanced. If the number of the single batteries to be equalized in each sub-battery pack is respectively as follows: 40, 25 and 5. The battery pack balancing device may store the battery labels of the single batteries to be balanced in each sub battery pack in the same storage area of the memory, for example, may store 40 single batteries to be balanced in the first sub battery pack in the same storage area of the memory.
And 208, balancing all or part of the N single batteries to be balanced in the balancing process.
The equalization process may include at least one of a current charging process of the battery pack, a discharging process after the current charging of the battery pack is completed, and a next charging process of the battery pack. The equalized single battery can be all or part of the N single batteries to be equalized.
The implementation process of step 208 may refer to the implementation processes of step 201 and step 202, and is not described in detail in the embodiment of the present invention.
It should be noted that, referring to fig. 4, when the balancing process is the current charging process of the battery pack and/or the next charging process of the battery pack, and the battery pack balancing apparatus balances all or part of the N single batteries to be balanced, the method may further include:
And 209, when the voltage of each of the M single batteries is greater than the first voltage threshold, stopping balancing the single batteries to be balanced.
In the embodiment of the invention, the battery pack balancing device can acquire the batteries of the M single batteries in real time in the balancing process. When the battery pack balancing device detects that the voltage of each single battery in the M single batteries is greater than the first voltage threshold value, it can be determined that the voltage difference of the battery pack is small, the consistency of the battery pack is good, and at the moment, balancing of the single batteries to be balanced can be stopped.
For example, if the battery pack includes single batteries that are all lithium iron phosphate batteries, the first voltage threshold may be 3550mv, and the battery pack balancing device may stop balancing the single batteries to be balanced when detecting that the voltage of each of the M single batteries is greater than 3550mv during the balancing process.
And step 210, setting the balancing identifier as a second identifier, and clearing the recorded battery labels of the single batteries to be balanced.
When the balancing of the single battery to be balanced is stopped, the battery pack balancing device may set the balancing flag to be the second flag (e.g., 0), and clear the recorded battery label of the single battery to be balanced. The second identifier may indicate that the battery pack does not need to be equalized during the discharging process and the next charging process of the battery pack.
Optionally, when the balancing process is a discharging process of the battery pack, when the battery pack balancing device detects that the balancing identifier is the first identifier, before balancing the single batteries to be balanced, it may further determine whether the minimum value of the voltages of the M single batteries is greater than a second voltage threshold, and when the minimum value of the voltages of the M single batteries is greater than the second voltage threshold, balance each single battery to be balanced.
Alternatively, the second voltage threshold may be determined according to the type of the battery pack. For example, if each unit cell in the battery pack is a lithium iron phosphate battery, the second voltage threshold may be 2900 mv. If each unit cell in the battery pack is a ternary cell, the second voltage threshold may be 3300 mv.
For example, if the first flag is 1 and the second voltage threshold is 2900mv, assuming that the battery pack balancing apparatus detects that the balancing flag is 1, and then detects that the minimum value of the voltages of the M single batteries is 3000mv and is greater than the second voltage threshold 2900mv, balancing of the battery pack is started.
In the embodiment of the invention, the capacity of each single battery in the discharging process is gradually reduced, and correspondingly, the voltage of each single battery is also gradually reduced. Therefore, when the battery pack balancing device detects that the minimum value of the voltages of the M single batteries is larger than the second voltage threshold value, the battery pack balancing device balances the battery pack to ensure that the capacities of the single batteries are consistent in the discharging process of the battery pack.
In the embodiment of the present invention, when the battery pack is equalized during the discharging process of the battery pack, the battery pack equalizing device may continue to detect the voltage of each single battery, and may stop equalizing the single batteries to be equalized when the minimum value of the voltages of the M single batteries is smaller than the second voltage threshold.
In the embodiment of the present invention, when the minimum value of the voltages of the M single batteries is smaller than the second voltage threshold, if the battery pack is continuously equalized, the single batteries with lower capacities may be equalized, so that the inconsistency of the capacities of the single batteries in the battery pack is aggravated, and the battery pack may be damaged. Therefore, when the battery pack balancing device balances the battery pack in the discharging process of the battery pack, when the minimum value of the voltages of the M single batteries is detected to be smaller than the second voltage threshold, the balancing needs to be stopped.
For example, assuming that the second voltage threshold is 2900mv, when the battery pack is equalized during the discharge of the battery pack, the equalization process may be stopped when the minimum value of the voltages of the M unit cells detected by the battery pack equalization apparatus is less than the second voltage threshold 2900 mv.
It should be noted that, after the equalization is stopped in the discharging process, the battery pack equalization apparatus may not modify the equalization flag, that is, may keep the equalization flag as the first flag, so that when the battery pack starts to be charged next time, the battery pack may continue to be equalized, so as to improve the equalization efficiency.
In the embodiment of the invention, in the balancing process of the battery pack, the battery pack balancing device can also monitor the state of each balancing loop in real time, and when the battery pack balancing device detects that the current in the balancing loop of the balanced single battery is 0, namely the balancing loop is broken, alarm information can be sent out to prompt an operator that the balancing loop has a fault, so that the operator can maintain the balancing loop in time.
In summary, the embodiments of the present invention provide a battery pack balancing method, where the battery pack may be divided into a plurality of sub battery packs. In the battery pack charging process, when it is detected that the battery pack meets the equalization condition, all or part of the N single batteries to be equalized can be equalized in at least one of the charging process of the battery pack, the discharging process after the battery pack is charged, and the next charging process of the battery pack, and the number of the equalized single batteries included in each sub battery pack is less than or equal to the number threshold. Therefore, in the balancing process of the battery pack, the situation that the temperature is too high and the balancing loop is burnt due to too many balanced single batteries can be avoided. In addition, the method provided by the embodiment of the invention can balance the battery pack in the whole charging process and the discharging process of the battery pack, thereby prolonging the balancing time and effectively improving the balancing efficiency.
The embodiment of the invention provides a battery pack balancing device, wherein the battery pack can comprise M single batteries, the M single batteries are divided into a plurality of sub battery packs, each sub battery pack comprises a plurality of single batteries which are connected in series, and M is a positive integer greater than 1. Referring to fig. 5, the apparatus may include:
the determining module 301 is configured to determine whether the battery pack satisfies an equalization condition according to the voltage difference between the M single batteries during the charging process of the battery pack.
A determining module 302, configured to determine, when the battery pack satisfies an equalization condition, N to-be-equalized single batteries from M single batteries included in the battery pack, where a voltage of each to-be-equalized single battery is greater than voltages of remaining single batteries, and N is a positive integer smaller than or equal to M/2.
The equalizing module 303 is configured to equalize all or part of the N single batteries to be equalized during an equalizing process, where the number of the equalized single batteries in each sub-battery pack is less than or equal to a number threshold, where the equalizing process may include at least one of a charging process of the battery pack at this time, a discharging process of the battery pack after the charging process is completed at this time, and a next charging process of the battery pack.
Optionally, the determining module 301 may include:
the obtaining submodule 3011 is configured to obtain a voltage of each unit cell during charging of the battery pack.
The first determining submodule 3012 is configured to determine voltage differences of the M single batteries when a maximum value of voltages of the M single batteries is greater than a first voltage threshold.
The second determining submodule 3013 is configured to determine the capacity difference of the M single batteries when the voltage difference is within the difference range.
A third determining sub-module 3014, configured to determine that the battery pack satisfies the balancing condition when the capacity difference is greater than a capacity difference threshold; and determining that the battery pack does not satisfy the equalization condition when the capacity difference is less than or equal to a capacity difference threshold.
Optionally, referring to fig. 5, the apparatus may further include: a setting module 304, configured to, after the determining module 301 determines whether the battery pack satisfies the equalization condition according to the voltage differences of the M single batteries,
when the battery pack meets the balance condition, setting the balance mark as a first mark; and when the battery pack does not meet the equalization condition, setting the equalization identifier as a second identifier.
The equalization module 303 may be configured to:
And detecting whether the equalization mark is the first mark.
And when the balancing identifier of the battery pack is the first identifier, balancing all or part of the to-be-balanced single batteries in the N to-be-balanced single batteries.
Optionally, as shown in fig. 5, the apparatus further includes: a recording module 305, configured to record a battery label of each to-be-equalized single cell in the N to-be-equalized single cells after the determining module 302 determines the N to-be-equalized single cells from the M single cells included in the battery pack.
The equalization module 303 may be configured to:
and in the balancing process, balancing all or part of the single batteries to be balanced according to the recorded battery labels of the single batteries to be balanced.
Optionally, the equalizing process is a current charging process of the battery pack and/or a next charging process of the battery pack, and the equalizing module 303 may further be configured to:
when the voltage of each single battery in the M single batteries is larger than the first voltage threshold value, the balancing of the single batteries to be balanced is stopped.
The setting module 304 is further configured to set the balancing identifier as a second identifier, and clear the recorded battery label of the single battery to be balanced.
Optionally, the balancing process is a discharging process after the charging of the battery pack is completed. The equalization module 303 may be configured to:
and when the minimum value of the voltages of the M single batteries is larger than a second voltage threshold value, balancing all or part of the N single batteries to be balanced.
And when the minimum value of the voltages of the M single batteries is smaller than a second voltage threshold value, stopping balancing the single batteries to be balanced.
Optionally, the recording module 305 may further be configured to: after the determining module 301 determines whether the battery pack satisfies the balancing condition, if the battery pack does not satisfy the balancing condition, the recorded battery labels of the single batteries to be balanced are cleared.
In summary, the present invention provides a battery pack balancing apparatus, in which the battery pack can be divided into a plurality of sub-battery packs. In the battery pack charging process, when the battery pack balancing device detects that the battery pack meets the balancing condition, all or part of the N single batteries to be balanced can be balanced in at least one of the charging process of the battery pack, the discharging process after the battery pack is charged and the next charging process of the battery pack, and the number of the balanced single batteries in each sub battery pack is smaller than or equal to the number threshold. Therefore, in the balancing process of the battery pack, the situation that the temperature is too high and the balancing loop is burnt due to too many balanced single batteries can be avoided. In addition, the device provided by the embodiment of the invention can balance the battery pack in the whole charging process and the discharging process of the battery pack, thereby prolonging the balancing time and effectively improving the balancing efficiency.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the apparatus, the modules and the sub-modules described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
Fig. 7 is a schematic structural diagram of another battery pack balancing apparatus according to an embodiment of the present invention. Referring to fig. 7, the apparatus may include: a processing component 401, a memory 402 and a computer program 4021 stored on the memory 402 and operable on the processing component 401, the processing component 401 implementing the battery pack balancing method as shown in fig. 1 to 4 when executing the computer program 4021.
An embodiment of the present invention further provides a computer-readable storage medium, in which instructions are stored, and when the computer-readable storage medium is run on a computer, the computer is caused to execute the battery pack balancing method shown in fig. 1 to 4.
The embodiment of the invention also provides a battery pack balancing system which can be applied to an electric automobile. The system may include: the battery pack includes M single batteries, the M single batteries correspond to the M resistors one to one and the M switches one to one, and M is a positive integer greater than 1.
Each resistor is connected with a corresponding switch in series, and the resistor and the switch which are connected in series can be connected with a corresponding single battery in parallel to form a balancing loop. Each switch may be connected to the battery equalization means for controlling the closing or opening of each switch. Alternatively, the switch may be a metal-oxide-semiconductor field-effect transistor (MOSFET).
In the embodiment of the invention, in the charging process of the battery pack or the discharging process of the battery pack, when the battery pack balancing device detects that the balancing identifier is the first identifier, the switch connected with all or part of the N single batteries to be balanced can be controlled to be closed, so that the balancing loop of the corresponding single battery to be balanced can be conducted, the electric energy of the single battery to be balanced is converted into heat energy through the resistor, the balancing of the battery pack is further realized, and the capacities of the M single batteries are kept consistent.
In addition, in the balancing process, if the battery pack balancing device detects that the voltages of the M single batteries are all larger than the first voltage threshold, the switch connected with each balanced single battery can be controlled to be disconnected, and the balancing of the battery pack is stopped.
Optionally, the battery pack balancing apparatus, the M resistors, and the M switches may be integrated on a circuit board, and the system may further include: a temperature sensor integrated on the circuit board. The temperature sensor may be used to detect the temperature of the circuit board. The battery pack balancing device is connected with the temperature sensor and can be used for controlling the on and off of each switch according to the temperature.
In the embodiment of the invention, when the battery pack is balanced, the heat energy of the resistor in the balancing loop is transferred to the circuit board, and the temperature sensor can acquire the heat energy generated by the resistor in the balancing loop by detecting the temperature of the circuit board in real time. The battery pack balancing device can compare the temperature acquired in real time with a pre-stored temperature threshold value and judge whether to balance the battery pack continuously:
when the battery pack balancing device determines that the temperature is greater than the temperature threshold, all switches connected with the balanced single batteries are disconnected, balancing of the battery pack is stopped, and therefore the situation that the balancing current is greater than the current threshold due to overhigh temperature and the balancing loop is burnt out is avoided, and safety and reliability of the balancing loop are guaranteed.
And when the battery pack balancing device determines that the temperature is less than the temperature threshold value, continuing to balance the battery pack. At this time, the equalization current of the battery pack equalization loop is small and can be smaller than the current threshold.
Alternatively, the current threshold may be 100 milliamps (mA) and the temperature threshold may be 65 degrees Celsius (C.). For example, assuming that the battery pack balancing device detects that the temperature of the circuit board is 68 ℃, when the temperature is greater than the temperature threshold of 65 ℃, all switches connected with the balanced single batteries are disconnected, and the balancing of the battery pack is stopped. If the battery pack balancing device detects that the temperature of the circuit board is 40 ℃, the battery pack is continuously balanced when the temperature of 40 ℃ is less than a temperature threshold value of 65 ℃. At this time, the equalization current of the battery equalization loop may be less than 100 mA.
It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.
The above description is only exemplary of the present invention and should not be taken as limiting the invention, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The battery pack balancing method is characterized in that the battery pack comprises M single batteries, the M single batteries are divided into a plurality of sub battery packs, each sub battery pack comprises a plurality of single batteries connected in series, and M is a positive integer greater than 1; the method comprises the following steps:
in the charging process of the battery pack, judging whether the battery pack meets an equalization condition or not according to the voltage difference of the M single batteries;
when the battery pack meets an equalization condition, determining N single batteries to be equalized from M single batteries included in the battery pack, wherein the voltage of each single battery to be equalized is greater than that of the rest single batteries, the N single batteries to be equalized are distributed in different sub battery packs, and N is a positive integer less than or equal to M/2;
in the balancing process, all or part of the N single batteries to be balanced are balanced, and the number of the balanced single batteries in each sub-battery pack is smaller than or equal to a number threshold, wherein the balancing process comprises at least one of the current charging process of the battery pack, the discharging process of the battery pack after the current charging process and the next charging process of the battery pack.
2. The method according to claim 1, wherein the determining whether the battery pack satisfies an equalization condition according to the voltage difference of the M single batteries during the charging of the battery pack comprises:
acquiring the voltage of each single battery in the charging process of the battery pack;
when the maximum value of the voltages of the M single batteries is larger than a first voltage threshold value, determining the voltage difference of the M single batteries;
when the voltage difference is within a difference range, determining the capacity difference of the M single batteries;
when the capacity difference is larger than a capacity difference threshold value, determining that the battery pack meets the balance condition;
determining that the battery pack does not satisfy the equalization condition when the capacity difference is less than or equal to a capacity difference threshold.
3. The method according to claim 1 or 2, wherein after determining whether the battery pack satisfies an equalization condition according to the voltage difference of the M unit cells, the method further comprises:
when the battery pack meets the equalization condition, setting an equalization identifier as a first identifier;
when the battery pack does not meet the equalization condition, setting an equalization identifier as a second identifier;
In the balancing process, balancing all or part of the N single batteries to be balanced includes:
detecting whether the equalization mark is the first mark;
and when the balancing identification of the battery pack is the first identification, balancing all or part of the to-be-balanced single batteries in the N to-be-balanced single batteries.
4. The method according to claim 3, wherein after determining N cells to be equalized from M cells included in the battery pack, the method further comprises:
recording the battery label of each monomer battery to be balanced in the N monomer batteries to be balanced;
in the balancing process, balancing all or part of the N single batteries to be balanced includes:
and in the balancing process, balancing all or part of the single batteries to be balanced according to the recorded battery labels of the single batteries to be balanced.
5. The method according to claim 4, wherein the equalization process is a current charging process of the battery pack and/or a next charging process of the battery pack, and in the process of equalizing all or part of the N single batteries to be equalized, the method further comprises:
When the voltage of each single battery in the M single batteries is larger than a first voltage threshold value, stopping balancing the single batteries to be balanced;
and setting the equalization identification as a second identification, and clearing the recorded battery label of the single battery to be equalized.
6. The method according to claim 4, wherein the balancing process is a discharging process after the battery pack is charged this time, and the balancing all or part of the N single batteries to be balanced includes:
when the minimum value of the voltages of the M single batteries is larger than a second voltage threshold value, balancing all or part of the N single batteries to be balanced;
the method further comprises the following steps:
and when the minimum value of the voltages of the M single batteries is smaller than a second voltage threshold value, stopping balancing the single batteries to be balanced.
7. The method according to any one of claims 4 to 6, wherein after determining whether the battery pack satisfies an equalization condition, the method further comprises:
and when the battery pack does not meet the equalization condition, clearing the recorded battery labels of the single batteries to be equalized.
8. The battery pack balancing device is characterized in that the battery pack comprises M single batteries, the M single batteries are divided into a plurality of sub battery packs, each sub battery pack comprises a plurality of single batteries connected in series, and M is a positive integer greater than 1; the device comprises:
the judging module is used for judging whether the battery pack meets an equalization condition or not according to the voltage difference of the M single batteries in the charging process of the battery pack;
the battery pack balancing method comprises a determining module, a balancing module and a balancing module, wherein the determining module is used for determining N single batteries to be balanced from M single batteries included in the battery pack when the battery pack meets a balancing condition, the voltage of each single battery to be balanced is larger than that of the rest single batteries, the N single batteries to be balanced are distributed in different sub battery packs, and N is a positive integer smaller than or equal to M/2;
and the equalizing module is used for equalizing all or part of the N single batteries to be equalized in an equalizing process, wherein the number of the equalized single batteries in each sub-battery pack is less than or equal to a number threshold, and the equalizing process comprises at least one of the current charging process of the battery pack, the discharging process of the battery pack after the charging process is completed and the next charging process of the battery pack.
9. A battery pack equalization system, the system comprising: the battery pack comprises a battery pack, a battery pack balancing device according to claim 8, M resistors and M switches, wherein the battery pack comprises M single batteries, the M single batteries are in one-to-one correspondence with the M resistors and in one-to-one correspondence with the M switches, and M is a positive integer greater than 1;
each resistor is connected with a corresponding switch in series, and the resistor and the switch which are connected in series are connected with a corresponding single battery in parallel to form a balance loop;
each switch is connected with the battery pack balancing device, and the battery pack balancing device is used for controlling the on/off of each switch.
10. The system of claim 9, wherein the battery pack balancing apparatus, the M resistors, and the M switches are integrated on a circuit board, the system further comprising: a temperature sensor integrated on the circuit board;
the temperature sensor is used for detecting the temperature of the circuit board;
the battery pack balancing device is connected with the temperature sensor and is also used for controlling the on and off of each switch according to the temperature.
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