CN110015170B - Battery equalization method, system, vehicle, storage medium and electronic device - Google Patents

Abstract

The present disclosure relates to a battery balancing method, system, vehicle, storage medium and electronic device. The method includes: acquiring an SOC value of at least one single cell in a battery pack; and according to the SOC of at least one single cell in the battery pack value and three intervals (0, SOC1), (SOC1, SOC2) and (SOC2, 100%) to determine the interval in which the SOC value of the at least one single battery is located; according to the SOC of the at least one single battery The interval in which the value is located, it is determined to use the SOC difference or the load voltage difference to determine the single cells that need to be balanced. This method is used for the three cases where the SOC value of at least one single cell in the battery pack is at (0, SOC1), or at (SOC1, SOC2) or at (SOC2, 100%), in each case, using The battery parameter information with higher accuracy is used to determine the single cells that need to be balanced, which improves the accuracy of determining the single cells that need to be balanced.

Description

Cell balancing method, system, vehicle, storage medium and electronic device

technical field

The present disclosure relates to the field of control technology, and in particular, to a battery balancing method, system, vehicle, storage medium, and electronic device.

Background technique

Large-capacity batteries that provide power for electric vehicles are often referred to as power batteries. Vehicle power batteries generally consist of multiple single cells connected in series to form a module. With the use of the battery, the differences between the single cells gradually expand, and the consistency between the single cells is poor. Due to the short-board effect of the battery, the capacity of the battery pack is limited, so that the capacity of the battery pack cannot be fully exerted, resulting in the battery pack's failure. The overall capacity is reduced. On the other hand, after the difference between the individual cells gradually expands, some cells will be overcharged and some cells will be overdischarged, which will affect the battery life and damage the battery, and may also generate a lot of heat and cause the battery burn or explode.

Therefore, the effective balanced management of electric vehicle power batteries is of great significance to improve the consistency of each battery in the battery pack, reduce the capacity loss of the battery, and prolong the service life of the battery and the cruising range of the electric vehicle.

At present, the balance management of the power battery pack requires firstly to determine the single cells that need to be balanced from the power battery pack. Therefore, it is necessary to collect the battery information of each single cell in the power battery pack in real time, and then according to the battery information To determine which single cells need to be balanced, and then balance the single cells that need to be balanced. Since the battery information of a single battery includes a variety of information, such as load voltage value, SOC value, etc., different types of battery information have different accuracy in different situations. The accuracy of the bulk battery is a problem that needs to be solved.

SUMMARY OF THE INVENTION

The purpose of the present disclosure is to provide a battery balancing method, system, vehicle, storage medium and electronic device to optimize the battery balancing process.

In order to achieve the above object, a first aspect of the present disclosure provides a battery balancing method, the method comprising:

Obtain the SOC value of at least one single cell in the battery pack;

According to the SOC value of at least one single cell in the battery pack and three intervals of (0, SOC1), (SOC1, SOC2) and (SOC2, 100%), determine where the SOC value of the at least one single cell is located range;

According to the interval in which the SOC value of the at least one single battery is located, it is determined to use the SOC difference value or the load voltage difference value to determine the single battery that needs to be balanced.

Optionally, the method further includes:

The value of SOC1 and the value of SOC2 are determined according to the corresponding relationship between the open circuit voltage OCV of the single battery and the SOC.

Optionally, the corresponding relationship between OCV and SOC satisfies: the rate of change of OCV with SOC in the interval (SOC1, SOC2) is less than the specified value, and the rate of change in the interval (0, SOC1) and the interval (SOC2, 100%) is greater than or equal to the specified value.

Optionally, according to the interval in which the SOC value of at least one single battery in the battery pack is located, determining to use the SOC difference value or the load voltage difference value to determine the single battery that needs to be balanced, including:

When the number of the SOC values of the individual cells in the battery pack belonging to the interval (0, SOC1) is greater than or equal to the first preset value, it is determined to use the load voltage difference to determine the single cells that need to be balanced;

When the number of SOC values belonging to the interval (SOC1, SOC2) among the SOC values of each single cell in the battery pack is greater than or equal to the second preset value, it is determined to use the SOC difference value to determine the single cells that need to be balanced;

When the number of SOC values belonging to the interval (SOC2, 100%) of the SOC values of the individual cells in the battery pack is greater than or equal to the third preset value, it is determined to use the load voltage difference to determine the cells that need to be balanced Battery.

Optionally, according to the interval in which the SOC value of at least one single battery in the battery pack is located, determining to use the SOC difference value or the load voltage difference value to determine the single battery that needs to be balanced, including:

determining a reference SOC value required for equalization according to the SOC value of at least one single cell in the battery pack;

When the reference SOC value belongs to the interval (SOC1, SOC2), it is determined to use the SOC difference value to determine the single cells that need to be balanced; otherwise, it is determined to use the load voltage difference to determine the single cells to be balanced.

Optionally, determining a reference SOC value required for equalization according to the SOC value of at least one single cell in the battery pack includes:

The SOC value of any single cell in the battery pack is determined as the reference SOC value.

Optionally, the specified value is the sampling accuracy of the voltage.

Optionally, when it is determined that the SOC difference is used to determine the single cells that need to be balanced, the method further includes:

Obtain the reference SOC value required for equilibrium;

determining the SOC difference between the SOC value of the at least one single cell and a reference SOC value required for equalization, wherein the reference SOC value required for equalization is determined according to the SOC value of each single cell in the battery pack of;

According to the SOC difference value and the first equalization opening threshold, it is determined that the single cells to be equalized are the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single battery.

Optionally, the reference SOC value is a minimum value among the SOC values of each single cell in the battery pack;

The determining of the SOC difference between the SOC value of the at least one single battery and the reference SOC value required for equalization includes:

Determine the SOC difference between the SOC values of the following cells and the reference SOC value required for equalization:

The single cell with the largest SOC value in the battery pack; or

Other single cells in the battery pack except the single cells whose SOC value is the minimum value.

Optionally, after determining that the single cell to be balanced is a single cell whose SOC difference in the at least one single cell is greater than or equal to the first equalization turn-on threshold, the method further includes:

Controlling the discharge of the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single cell.

Optionally, the reference SOC value is the maximum value among the SOC values of each single cell in the battery pack;

The determining of the SOC difference between the SOC value of the at least one single battery and the reference SOC value required for equalization includes:

Determine the SOC difference between the SOC values of the following cells and the reference SOC value required for equalization:

The single cell with the smallest SOC value in the battery pack; or

Other single cells in the battery pack except the single cells with the SOC value of the maximum value.

Optionally, after determining that the single cell to be balanced is a single cell whose SOC difference in the at least one single cell is greater than or equal to the first equalization turn-on threshold, the method further includes:

Controlling the charging of the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single cell.

Optionally, the reference SOC value is an average value of the SOC values of the individual cells in the battery pack;

The determining of the SOC difference between the SOC value of the at least one single battery and the reference SOC value required for equalization includes:

A SOC difference between the SOC value of each single cell in the battery pack and the reference SOC value is determined.

Optionally, after determining that the single cell to be balanced is a single cell whose SOC difference in the at least one single cell is greater than or equal to the first equalization turn-on threshold, the method further includes:

For any single cell whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single cell, when the SOC value of the single cell is greater than the reference SOC value, control the single cell discharging, and, when the SOC value of the single cell is less than the reference SOC value, controlling the single cell to charge.

Optionally, after determining that the single cell to be balanced is a single cell whose SOC difference in the at least one single cell is greater than or equal to the first equalization turn-on threshold, the method further includes:

For any single cell whose SOC difference in the at least one single cell is greater than or equal to the first equalization turn-on threshold, determine the SOC value of the single cell according to the SOC value of the single cell and the reference SOC value. target equilibrium duration;

According to the target equalization duration of the single cell, the equalization of the single cell is controlled.

Optionally, when it is determined that the load voltage difference is used to determine the single cells that need to be balanced, the method further includes:

Determine the reference load voltage value required for balancing according to the load voltage value of each single cell in the battery pack;

determining a load voltage difference between the load voltage value of the at least one single cell and the reference load voltage value;

According to the load voltage difference and the second equalization opening threshold, it is determined that the single cells to be equalized are the single cells whose load voltage difference is greater than or equal to the second equalization opening threshold in the at least one single cell.

Optionally, the reference load voltage value is a minimum value among the load voltage values of each single cell in the battery pack;

The determining of the load voltage difference between the load voltage value of the at least one single cell and the reference load voltage value includes:

Determine the load voltage difference between the load voltage value of the following single cell and the reference load voltage value:

The single cell with the largest load voltage value in the battery pack; or

Other single cells in the battery pack except the single cells whose load voltage value is the minimum value.

Optionally, after determining that the single cell to be balanced is a single cell whose load voltage difference in the at least one single cell is greater than or equal to the second equalization turn-on threshold, the method further includes:

Controlling the discharge of a single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell.

Optionally, the reference load voltage value is the maximum value among the load voltage values of each single cell in the battery pack;

The determining of the load voltage difference between the load voltage value of the at least one single cell and the reference load voltage value includes:

Determine the load voltage difference between the load voltage value of the following single cell and the reference load voltage value:

The single cell with the smallest load voltage value in the battery pack; or

Other single cells in the battery pack except the single cells whose load voltage value is the maximum value.

Optionally, after determining that the single cell to be balanced is a single cell whose load voltage difference in the at least one single cell is greater than or equal to the second equalization turn-on threshold, the method further includes:

Controlling the charging of a single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell.

Optionally, the reference load voltage value is an average value of the load voltage values of the individual cells in the battery pack;

The determining of the load voltage difference between the load voltage value of the at least one single cell and the reference load voltage value includes:

A load voltage difference between the load voltage value of each single cell in the battery pack and the reference load voltage value is determined.

Optionally, after determining that the single cell to be balanced is a single cell whose load voltage difference in the at least one single cell is greater than or equal to the second equalization turn-on threshold, the method further includes:

For any single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell, when the load voltage value of the single cell is greater than the reference load voltage difference, control the The single battery is discharged, and when the load voltage value of the single battery is less than the reference load voltage difference, the single battery is controlled to be charged.

Optionally, after determining that the single cell to be balanced is a single cell whose load voltage difference in the at least one single cell is greater than or equal to the second equalization turn-on threshold, the method further includes:

For any single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell, determine the single cell according to the load voltage value of the single cell and the reference load voltage value. The target equalization time of the body battery;

According to the target equalization duration of the single cell, the equalization of the single cell is controlled.

Optionally, the method for calculating the SOC value includes a first calculation method and a second calculation method, the first calculation method corresponds to an interval (0, SOC1) and an interval (SOC2, 100%), and the second calculation method corresponds to in the interval (SOC1, SOC2);

The acquiring the SOC value of each single cell in the battery pack includes:

For any single cell in the battery pack, determine the SOC value of the single cell according to the first calculation method;

When the SOC value determined according to the first calculation method belongs to the interval (SOC1, SOC2), the SOC value of the single battery is re-determined according to the second calculation method.

Optionally, the first calculation method is the method used by the single battery to calculate the SOC value last time.

Optionally, the first calculation method is the ampere-hour integration method or the ampere-hour integration combined with the voltage correction method, and the second calculation method is the ampere-hour integration method and the ampere-hour integration combined with the voltage correction method and the first calculation method. different calculation methods.

A second aspect of the present disclosure provides a battery balancing system, including:

Equalization module, acquisition module and control module,

The acquisition module is used to acquire the SOC value of at least one single cell in the battery pack;

The control module is configured to determine the SOC value of the at least one single cell in the battery pack according to the SOC value of the at least one single cell and three intervals (0, SOC1), (SOC1, SOC2) and (SOC2, 100%). The interval in which the SOC value is located, and, according to the interval in which the SOC value of the at least one single battery is located according to the SOC value of the at least one single battery, it is determined to use the SOC difference value or the load voltage difference value to determine the single battery that needs to be balanced ;

The equalization module is used to equalize the single cells that need to be equalized.

Optionally, the control module is used to:

The value of SOC1 and the value of SOC2 are determined according to the corresponding relationship between the open circuit voltage OCV of the single battery and the SOC.

Optionally, the corresponding relationship between OCV and SOC satisfies: the rate of change of OCV with SOC in the interval (SOC1, SOC2) is less than the specified value, and the rate of change in the interval (0, SOC1) and the interval (SOC2, 100%) is greater than or equal to the specified value.

Optionally, the control module is used to:

When the number of the SOC values of the individual cells in the battery pack belonging to the interval (0, SOC1) is greater than or equal to the first preset value, it is determined to use the load voltage difference to determine the single cells that need to be balanced;

When the number of SOC values belonging to the interval (SOC1, SOC2) among the SOC values of each single cell in the battery pack is greater than or equal to the second preset value, it is determined to use the SOC difference value to determine the single cells that need to be balanced;

When the number of SOC values belonging to the interval (SOC2, 100%) of the SOC values of the individual cells in the battery pack is greater than or equal to the third preset value, it is determined to use the load voltage difference to determine the cells that need to be balanced Battery.

Optionally, the control module is used to:

determining a reference SOC value required for equalization according to the SOC value of at least one single cell in the battery pack;

When the reference SOC value belongs to the interval (SOC1, SOC2), it is determined to use the SOC difference value to determine the single cells that need to be balanced; otherwise, it is determined to use the load voltage difference to determine the single cells to be balanced.

Optionally, the reference SOC value is a minimum value, a maximum value or an average value among the SOC values of the individual cells in the battery pack.

Optionally, the specified value is the sampling accuracy of the voltage.

Optionally, the control module is used to:

Obtain the reference SOC value required for equilibrium;

determining the SOC difference between the SOC value of the at least one single cell and a reference SOC value required for equalization, wherein the reference SOC value required for equalization is determined according to the SOC value of each single cell in the battery pack of;

According to the SOC difference value and the first equalization opening threshold, it is determined that the single cells to be equalized are the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single battery.

Optionally, the control module is used to:

For any single cell whose SOC difference in the at least one single cell is greater than or equal to the first equalization turn-on threshold, determine the SOC value of the single cell according to the SOC value of the single cell and the reference SOC value. target equilibrium duration;

The equalization module is used for:

According to the target equalization duration of the single cell, the single cell is balanced.

Optionally, the control module is used to:

Determine the reference load voltage value required for balancing according to the load voltage value of each single cell in the battery pack;

determining a load voltage difference between the load voltage value of the at least one single cell and the reference load voltage value;

According to the load voltage difference and the second equalization opening threshold, it is determined that the single cells to be equalized are the single cells whose load voltage difference is greater than or equal to the second equalization opening threshold in the at least one single cell.

Optionally, the reference load voltage value is a minimum value, a maximum value or an average value among the load voltage values of the individual cells in the battery pack.

Optionally, the control module is used to:

For any single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell, determine the single cell according to the load voltage value of the single cell and the reference load voltage value. The target equalization time of the body battery;

The equalization module is used for:

According to the target equalization duration of the single cell, the equalization of the single cell is controlled.

Optionally, the method for calculating the SOC value includes a first calculation method and a second calculation method, the first calculation method corresponds to an interval (0, SOC1) and an interval (SOC2, 100%), and the second calculation method corresponds to in the interval (SOC1, SOC2);

The acquisition module is used for:

For any single cell in the battery pack, determine the SOC value of the single cell according to the first calculation method;

When the SOC value determined according to the first calculation method belongs to the interval (SOC1, SOC2), the SOC value of the single battery is re-determined according to the second calculation method.

Optionally, the first calculation method is the method used by the single battery to calculate the SOC value last time.

Optionally, the first calculation method is the ampere-hour integration method or the ampere-hour integration combined with the voltage correction method, and the second calculation method is the ampere-hour integration method and the ampere-hour integration combined with the voltage correction method and the first calculation method. different calculation methods.

Optionally, the control module is connected to the acquisition module and the equalization module corresponding to the same single cell through a channel, and the control module is used to control the cell when it is determined that the single cell connected to the control module does not need to be equalized. The control module is connected with the corresponding sampling module; or,

The control module is further configured to time-division multiplex the channel when determining that the single battery connected to the control module needs to be balanced.

Optionally, the control module includes a control chip, and the control chip is connected to the acquisition module and the equalization module corresponding to the same single battery through one pin and the one channel.

Optionally, the control module is respectively connected with the acquisition module and the equalization module corresponding to the same single cell through two channels.

Optionally, the control module includes a control chip, and the control chip is respectively connected to the acquisition module and the equalization module corresponding to the same single battery through two pins, and the two pins are one with the two channels. A correspondence.

A third aspect of the present disclosure provides a computer-readable storage medium on which computer program instructions are stored, and when the program instructions are executed by a processor, implement the method described in the first aspect of the present disclosure.

A fourth aspect of the present disclosure provides an electronic device, comprising:

The computer-readable storage medium of the third aspect of the present disclosure; and

One or more processors for executing programs in the computer-readable storage medium.

A fifth aspect of the present disclosure provides a vehicle comprising: a battery pack and the battery balancing system according to the second aspect of the present disclosure.

Through the above technical solution, the SOC difference value is determined according to which interval the SOC value of at least one single cell in the battery pack is in (0, SOC1), (SOC1, SOC2) and (SOC2, 100%). It is also the load voltage difference value to determine the single cells that need to be balanced, and the SOC value of at least one single cell in the battery pack is at (0, SOC1), or at (SOC1, SOC2) or at (SOC2, 100%) these three In each case, the battery parameter information with higher accuracy is used to determine the single cells that need to be balanced, which improves the accuracy of determining the single cells that need to be balanced.

Other features and advantages of the present disclosure will be described in detail in the detailed description that follows.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present disclosure, and constitute a part of the specification, and together with the following detailed description, are used to explain the present disclosure, but not to limit the present disclosure. In the attached image:

FIG. 1 is a schematic diagram of a battery balancing system according to an embodiment of the present disclosure;

2 is a schematic diagram of a battery balancing system in which two single cells share one balancing module according to an embodiment of the present disclosure;

3 is a schematic diagram of a battery balancing system according to another embodiment of the present disclosure;

4 is a schematic diagram of a battery balancing system in which two single cells share one balancing module according to another embodiment of the present disclosure;

FIG. 5 is a schematic flowchart of a battery balancing method according to an embodiment of the present disclosure;

FIG. 6 is an open circuit voltage OCV-remaining power SOC curve of a single battery according to an embodiment of the present disclosure;

7 is a schematic diagram of a battery internal resistance model according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of an equalization module according to an embodiment of the present disclosure.

Detailed ways

The specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, but not to limit the present disclosure.

Referring to FIG. 1 , it is a schematic diagram of a battery balancing system according to an embodiment of the present disclosure. The battery balance system includes: a control module 101 , a collection module 102 , a balance module 103 and a battery pack 104 .

In one embodiment, each single cell corresponds to one acquisition module 102 and one equalization module 103 . The acquisition module 102 and the equalization module 103 corresponding to the same single cell are respectively connected to the control module 101 through different control channels. The control module may include a control chip, the control chip is respectively connected with the acquisition module and the equalization module corresponding to the same single battery through two pins, and the two pins are in one-to-one correspondence with the two channels.

In this embodiment, the control module 101 controls the acquisition module 102 and the equalization module 103 to be turned on in a time-sharing manner according to a unit period, and performs battery information acquisition and battery equalization respectively, so that the battery information acquisition and equalization are performed in a time-sharing manner. When the battery information collection and equalization are performed at the same time, the influence of the equalization current on the accuracy of the battery information collection is avoided.

In one embodiment, as shown in FIG. 1 , each single cell in the battery is connected to a collection module 102 and an equalization module 103 respectively. If the battery pack includes N single cells, the number of acquisition modules 102 is N, and the number of equalization modules 103 is N. Therefore, the control module 101 communicates with the N acquisition modules and N equalization modules through 2×N control channels, respectively. connect.

In other embodiments, different cells may share the equalization module, for example, N cells in the battery pack may share the same equalization module, or each preset number (for example, 2, 3 or 5, etc.) single cells share a balancing module, etc. When there are at least two single cells in the multi-cell cells that share one equalization module and need to be equalized, within the equalization period of the unit cycle, the equalization module and each cell of the at least two single cells to be equalized need to be equalized. Batteries are connected alternately.

Referring to FIG. 2 , two single cells share one equalization module. When two single cells sharing one equalization module need to be equalized, the equalization module is alternately connected to each single cell during the equalization period of a unit cycle. The alternate connection may be alternately connected according to a certain period. For example, referring to FIG. 2 , when the parallel switch 150 on the parallel branch 15 corresponding to one single cell 111 of the two single cells is closed for 2s under the control of the control module 14, the other one of the two single cells is closed for 2 s. The parallel switch 150 on the parallel branch 15 corresponding to the single cell 111 is turned off for 2 s under the control of the control module 14 . That is, the parallel switch 150 on the parallel branch 15 corresponding to each single cell 111 in the two single cells switches from the closed state to the open state or from the open state every two seconds during the equalization period. Switch to closed state. Therefore, based on the time-sharing conduction of the acquisition module and the equalization module, during the equalization period, the single cells sharing the same equalization module are alternately connected to the shared equalization module to achieve equalization.

Referring to FIG. 3 , it is a schematic structural diagram of a battery balancing system according to another embodiment of the present disclosure.

The battery balance system includes: a control module 301 , a collection module 302 , a balance module 303 and a battery pack 304 . The battery pack 304 includes a plurality of single cells connected in series. The control module 301 is connected to the acquisition module 302 and the equalization module 303 corresponding to the same single cell through a control channel 305 . The control module is used to control the connection of the control module with the corresponding sampling module when it is determined that the single battery connected to the control module does not need to be balanced; or, the control module is also used to determine that the single battery connected to the control module needs to be When performing equalization, the acquisition module and the equalization module time-division multiplex the channel 305 according to the unit period.

A unit period includes: acquisition period and equalization period. The control module 301 controls the acquisition module 302 to sample the battery information of the single battery within the acquisition period to obtain the battery information of the single battery. The battery information includes at least one of the following: voltage, current, temperature, etc. In one embodiment, the battery information may only include the voltage value, and thus, the voltage performance parameter of the single battery may be obtained. In another embodiment, the battery information may also include a voltage value, a current value, a temperature value, and the like, so that performance parameters such as SOC, internal resistance, and self-discharge rate of the single battery can be obtained.

The control module 301 determines, according to the battery information of the single cells collected by the collection module 302, the single cells to be balanced that need to be balanced. For the single cells to be balanced that need to be balanced, the control module 301 controls the equalization module corresponding to the single cells to be balanced, and balances the single cells to be balanced during the equalization period.

Therefore, in the embodiment of the present disclosure, the acquisition module and the equalization module share the same control channel, the control module controls the acquisition module and the equalization module, and time-division multiplexes the control channel according to the unit period, which avoids the simultaneous acquisition of battery information and equalization During the process, the effect of equalizing current on the accuracy of battery information collection; on the other hand, compared with the embodiment shown in FIG. 1 above, the requirement for the number of channels of the control module chip is reduced, which can save hardware costs.

In one embodiment, a switch K is provided in the control channel shared by the acquisition module and the equalization module. The control module 301 is connected to the switch K, and is connected to the acquisition module 302 or the equalization module 303 in time-sharing by controlling the switch K. When the switch K is connected to the acquisition module 302, the control module 301 controls the acquisition module 302 to collect battery information for the single cells during the acquisition cycle; when the switch K is connected to the equalization module 303, the control module 301 controls the equalization module 303 Balance the corresponding single cells.

In one embodiment, as shown in FIG. 1 , each single cell in the battery is connected to a collection module 302 and an equalization module 303 respectively. If the battery pack includes N single cells, the number of acquisition modules 302 is N, and the number of equalization modules 303 is N. Therefore, the control module 301 is respectively connected to the acquisition module and the equalization module through N control channels.

In other embodiments, different cells may share the equalization module, for example, N cells in the battery pack may share the same equalization module, or each preset number (for example, 2, 3 or 5, etc.) single cells share a balancing module, etc. When there are at least two single cells in the multi-cell cells that share one equalization module and need to be equalized, within the equalization period of the unit cycle, the equalization module and each cell of the at least two single cells to be equalized need to be equalized. Batteries are connected alternately.

Referring to FIG. 4 , it is an exemplary schematic diagram of two single cells sharing one equalization module. When two single cells sharing one balancing module need to be balanced, the balancing module is alternately connected to each single cell during the balancing period of the unit cycle. The alternate connection may be alternately connected according to a certain period. Therefore, based on the time-sharing conduction of the acquisition module and the equalization module, during the equalization period, the single cells sharing the same equalization module are alternately connected to the shared equalization module to achieve equalization.

In one embodiment, the collection module may be a voltage collection chip, which is used to collect the voltage of the single cell during the collection period.

Referring to FIG. 5 , based on the battery balancing system shown in any of the above embodiments of FIG. 1 , FIG. 2 , FIG. 3 or FIG. 4 , a battery balancing method according to an embodiment of the present disclosure includes:

In step S51, the SOC value of at least one single cell in the battery pack is obtained.

In step S52, the at least one single cell is determined according to the SOC value of at least one single cell in the battery pack and three intervals of (0, SOC1), (SOC1, SOC2) and (SOC2, 100%). The interval in which the SOC value is located.

In step S53, according to the interval in which the SOC value of the at least one single battery is located, it is determined to use the SOC difference value or the load voltage difference value to determine the single battery that needs to be balanced.

First, step S51 will be described.

In one embodiment, the method for calculating an SOC value includes a first calculation method and a second calculation method, the first calculation method corresponds to an interval (0, SOC1) and an interval (SOC2, 100%), and the second calculation method The mode corresponds to the interval (SOC1, SOC2);

Correspondingly, step S51 includes:

For any single cell in the battery pack, determine the SOC value of the single cell according to the first calculation method;

When the SOC value determined according to the first calculation method belongs to the interval (SOC1, SOC2), the SOC value of the single battery is re-determined according to the second calculation method.

Optionally, the first calculation method is the method used by the single battery to calculate the SOC value last time.

Optionally, the first calculation method is the ampere-hour integration method or the ampere-hour integration combined with the voltage correction method, and the second calculation method is the ampere-hour integration method and the ampere-hour integration combined with the voltage correction method and the first calculation method. different calculation methods.

The ampere-hour integration method means that the SOC value of the single battery is obtained by integrating the current value of the single battery collected with time; the ampere-hour integration method combined with the voltage correction method means that the ampere-hour integration method is used to calculate the SOC value of the single battery first. , and then use the load voltage value of the single battery to correct the calculated SOC value, and use the corrected SOC value as the final SOC value of the single battery.

In the embodiment of the present disclosure, it is considered that there is an OCV plateau period on the OCV-SOC curve of a single battery, and during the OCV plateau period, the variation of the OCV value is small. For example, FIG. 6 is a schematic diagram of the OCV-SOC curve of a single battery. . As shown in Fig. 6, in the [SOC1, SOC2] interval, the OCV value of the single battery changes very little. Therefore, in the OCV plateau period, the SOC value of the single cell cannot be accurately calculated by using the OCV value, which leads to the failure to accurately determine the single cell that needs to be balanced.

Among them, the OCV value is the open circuit voltage value of the single cell, which is different from the load voltage value. Referring to Figure 7 and Equation (1), when the battery pack is in the discharge state or the charge state, the battery internal resistance model is adopted, and the single battery is equivalent to an ideal voltage source and the resistor R is connected in series. Then for a single battery, the sampled voltage value _VL (ie, the load voltage value) of the single battery can be converted into an open-circuit voltage value according to formula (1):

OCV= _VL +I×R (1)

Among them, _VL is the load voltage value collected by the collection module during the collection period; I is the discharge current or charging current collected by the collection module during the collection period; R is the internal resistance value of the single battery.

Or, in another embodiment, the voltage collected at the moment when the single battery to be equalized stops working and reaches a stable state, or the battery just starts working is itself an open-circuit voltage or can be approximately regarded as an open-circuit voltage, so in this case The OCV value of the single cell to be equalized can be directly collected and obtained.

Or, in another embodiment, the voltage collected at the moment when the battery to be referenced stops working and reaches a stable state, or the battery just starts working, is itself an open-circuit voltage or can be approximately regarded as an open-circuit voltage, so in this case, it can be The OCV value of the reference battery is directly collected.

The internal resistance value of the single battery can be preset. Or the internal resistance value of the single battery can be determined according to the voltage and capacity of the single battery. For example, the internal resistance value of the single battery is determined according to the corresponding relationship between the voltage, the capacity and the internal resistance value of the single battery. It should be understood that other battery models, such as: Thevenin (Thevenin) model, PNGV (Partnership for a New Generation of Vehicles) model, etc., can also be used to convert the collected load voltage of the single battery into open circuit voltage.

Therefore, the load voltage value is collected, and the following relationship exists between the load voltage value and the OCV value:

OCV value = load voltage value + battery internal resistance * battery charging current or discharging current

Under normal circumstances, the internal resistance of the battery and the charging current or discharging current of the battery are constant. Therefore, the difference between the OCV value and the load voltage value is also constant. When the change range of the OCV value is small, the change range of the load voltage value Also small.

In order to accurately calculate the SOC value of a single battery, the present disclosure proposes not to use the ampere-hour integration combined with the voltage correction method to calculate the SOC value during the OCV plateau period, but to use the ampere-hour integration method to calculate the SOC value, so as to avoid using the ampere-hour integration method during the OCV plateau period. The time integration combined with the voltage correction method to calculate the SOC value leads to the inaccuracy of the calculated SOC value.

The present disclosure also considers that in the non-OCV plateau period, the OCV value varies greatly. For example, as shown in FIG. 6 , in the interval [0, SOC1] and [SOC2, 100%], the OCV value of the single battery changes larger. Therefore, in the non-OCV plateau period, it is more accurate to use the ampere-hour integration combined with the voltage correction method to calculate the SOC value of the single battery.

According to the OCV-SOC curve of the single battery, the present disclosure divides the value range of the SOC value of the single battery into three intervals: a first interval, a second interval and a third interval, and the second interval corresponds to the OCV plateau period SOC interval, such as the [SOC1, SOC2] interval in Figure 6; the first interval and the third interval are the SOC intervals corresponding to the non-OCV plateau period, such as the [0, SOC1] interval and [SOC2, 100 in Figure 6] %]. The embodiments of the present disclosure propose to use the ampere-hour integration method to calculate the SOC value of the single battery in the SOC interval corresponding to the OCV plateau period, and use the ampere-hour integration combined with the voltage correction method to calculate the SOC value of the single battery in the SOC interval corresponding to the non-OCV plateau period . Wherein, OCV is Open Circuit Voltage, and SOC is State of Charge.

In the embodiment of the present disclosure, since the voltage change rate is relatively large in the first interval and the third interval, the ampere-hour integration method can be used, and the SOC value of the battery can be calculated by correcting with the real-time voltage of the battery (in this case, the load voltage). In the second interval, due to the small change rate of the battery voltage, the accuracy of calculating the SOC value by introducing a voltage variable is not high, so the ampere-hour integration method can be directly used to calculate the SOC value. In this way, it is possible to further determine how to obtain the SOC value of the single battery according to the different SOC value intervals of the single battery. Therefore, the obtained SOC value of the single battery is more accurate, thereby making the determined needs Balanced single cells are also more accurate.

In another embodiment, at the moment when the battery just works, the SOC value of the battery can also be calculated by the open circuit voltage method, that is, the voltage value of the battery is collected (equivalent to the open circuit voltage value at this time), and the corresponding relationship between OCV and SOC can be checked. Calculate the battery SOC value.

For any single battery in the battery pack, first calculate the SOC value of the single battery by using either the ampere-hour integration method or the ampere-hour integration combined with the voltage correction method, and the calculation method used at this time is the first calculation. Way. Then judge whether the calculated SOC value belongs to the SOC interval corresponding to the OCV plateau period. If the calculated SOC value does not belong to the SOC interval corresponding to the OCV plateau period, it means that the calculated SOC value belongs to the SOC interval corresponding to the non-OCV plateau period. Since it is more accurate to use the ampere-hour integration combined with the voltage correction method in the SOC interval corresponding to the non-OCV plateau period, the SOC value of the single battery is recalculated according to the ampere-hour integration combined with the voltage correction method. Optionally, in this case, If the SOC value of the single battery is calculated again, the ampere-hour integration combined with the voltage correction method can be used as the first calculation method; if the calculated SOC value belongs to the SOC interval corresponding to the OCV plateau period, it means that the calculated SOC value is accurate Yes, there is no need to recalculate the SOC value of the single battery. Optionally, in this case, if the SOC value of the single battery is calculated again, the ampere-hour integration method can be used as the first calculation method.

Or, determine whether the calculated SOC value belongs to the SOC interval corresponding to the non-OCV plateau period. If the calculated SOC value does not belong to the SOC interval corresponding to the non-OCV plateau period, it means that the calculated SOC value belongs to the SOC corresponding to the OCV plateau period. In the SOC interval corresponding to the OCV plateau period, the ampere-hour integration method is more accurate than the ampere-hour integration combined with the voltage correction method, so the SOC value of the single battery is recalculated according to the ampere-hour integration method. Optionally, here In this case, if the SOC value of the single battery is calculated again, the ampere-hour integration method can be used as the first calculation method; if the calculated SOC value belongs to the SOC range corresponding to the non-OCV plateau period, it means that the calculated SOC value is Accurately, there is no need to recalculate the SOC value of the single battery. Optionally, in this case, if the SOC value of the single battery is calculated again, the ampere-hour integration combined with the voltage correction method can be used as the first calculation method.

The above is the whole process of calculating the SOC value of the single battery provided in the present disclosure.

In order to accurately determine the single cells that need to be balanced, the embodiments of the present disclosure propose to first obtain the SOC value of at least one single cell in the battery pack, and then determine the at least one single cell according to the SOC value of at least one single cell in the battery pack. The SOC value of the bulk battery belongs to which of the three intervals (0, SOC1), (SOC1, SOC2) and (SOC2, 100%), and then determines the SOC difference or the load voltage difference to determine the need to be balanced. single battery.

Optionally, the method further includes: determining the value of SOC1 and the value of SOC2 according to the corresponding relationship between the open circuit voltage OCV of the single battery and the SOC.

The values of SOC1 and SOC2 can be determined according to the corresponding relationship between the open circuit voltage OCV and SOC of the single battery. In one embodiment, the corresponding relationship between the open circuit voltage OCV and the SOC satisfies that the rate of change of the OCV with the SOC in the interval (SOC1, SOC2) is less than a specified value, and in the interval (0, SOC1) and the interval (SOC2, 100%) is greater than or equal to the specified value. In one embodiment, the specified value is the sampling accuracy of the voltage.

It is determined whether the SOC difference value or the load voltage difference value is selected to determine the single cells that need to be balanced, and there are but are not limited to the following two implementations:

The first embodiment: when the number of SOC values of each single cell in the battery pack belonging to the interval (0, SOC1) is greater than or equal to the first preset value, it is determined to use the load voltage difference to determine the need for equalization When the number of SOC values belonging to the interval (SOC1, SOC2) is greater than or equal to the second preset value among the SOC values of each single battery in the battery pack, it is determined to use the SOC difference value to determine the need for equalization When the number of SOC values belonging to the interval (SOC2, 100%) of the SOC values of each single battery in the battery pack is greater than or equal to the third preset value, the load voltage difference is determined to be used to determine Balanced single cells are required.

Referring to Figure 6, during the charging or discharging process of the battery pack, when the SOC value of the single cell is in the interval (0, SOC1) and (SOC2, 100%), the consistency of the single cell is evaluated by the load voltage difference difference to determine the cells that need to be equalized. When the SOC value of the single battery is in the interval (SOC1, SOC2), the charge or discharge of the single battery is obtained by the ampere-hour integration method, so as to determine the real-time SOC value of the single battery, which can avoid using the voltage to calculate the SOC value The resulting error can effectively improve the reliability of the SOC. Therefore, in this interval (SOC1, SOC2), the consistency difference of the single cells is evaluated through the SOC difference to determine the single cells that need to be balanced.

Therefore, in an embodiment of the present disclosure, when the number of the SOC values of the individual cells in the battery pack belonging to the interval (0, SOC1) is greater than or equal to the first preset value (for example: the cells in the battery pack) 1/3 of the total number of batteries), it is determined to use the load voltage difference to determine the single battery that needs to be balanced.

When the number of SOC values belonging to (SOC1, SOC2) among the SOC values of each single cell in the battery pack is greater than or equal to the second preset value (for example: 1/2 of the total number of single cells in the battery pack), It is determined to use the SOC difference to determine the single cells that need to be balanced.

When the number of SOC values belonging to (SOC2, 100%) of the SOC values of each single cell in the battery pack is greater than or equal to the third preset value (for example: 1/3 of the total number of single cells in the battery pack) , determine the use of the load voltage difference to determine the single cells that need to be balanced.

That is to say, if the SOC values of most of the cells in the battery pack belong to the interval (0, SOC1) or (SOC2, 100%), it is determined to use the load voltage difference to determine the cells that need to be balanced. The SOC values of most of the single cells belong to the interval (SOC1, SOC2), and the SOC difference is determined to be used to determine the single cells that need to be balanced.

Second implementation:

According to the SOC value of at least one single battery in the battery pack, the reference SOC value required for balancing is determined; when the reference SOC value belongs to the interval (SOC1, SOC2), it is determined to use the SOC difference value to determine the single battery that needs to be balanced. battery; otherwise, it is determined to use the load voltage difference to determine the single battery that needs to be balanced.

In the second embodiment, the reference SOC value may be the SOC value of any single cell in the battery pack, for example: the SOC value of the single cell with the largest SOC value in the battery pack, or the SOC value of the smallest SOC value in the battery pack The SOC value of the single cell, or the SOC value of the single cell whose SOC value is in the middle of the battery pack (for the case where the battery pack includes an odd number of single cells).

The reference SOC value can also be calculated according to the SOC value of each single cell in the battery pack, for example: the average value of the SOC value of each single cell in the battery pack, or, the SOC value in the battery pack is in the middle The average value of the SOC values of the two cells (for the case where the battery pack includes an even number of cells).

Compare the reference SOC value with (SOC1, SOC2), if the reference SOC value belongs to (SOC1, SOC2), select the SOC difference to determine the single battery that needs to be balanced; if the reference SOC value does not belong to (SOC1, SOC2), Then the load voltage difference is selected to determine the single cells that need to be balanced.

The above is the process of determining whether the SOC difference value or the load voltage difference value is selected to determine the single cells that need to be balanced. The following describes the case of selecting the SOC difference to determine the single cells to be balanced, and the case of selecting the load voltage difference to determine the single cells to be balanced.

First, the case where the SOC difference is selected to determine the single cells that need to be balanced will be described. Specifically include the following steps:

Obtain the reference SOC value required for equilibrium;

determining the SOC difference between the SOC value of the at least one single cell and a reference SOC value required for equalization, wherein the reference SOC value required for equalization is determined according to the SOC value of each single cell in the battery pack of;

According to the SOC difference value and the first equalization opening threshold, it is determined that the single cells to be equalized are the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single battery.

For the description of the reference SOC value required for the balance judgment, reference may be made to the foregoing description, which will not be repeated here. The first equalization turn-on threshold is a threshold used to determine whether to turn on equalization for any single cell in the battery pack, that is, a threshold used to determine whether any single cell in the battery pack is a single cell that needs to be balanced.

First, select at least one single cell from the battery pack, and then make a difference between the SOC value of the selected at least one single cell and the reference SOC value to obtain the SOC difference value of the selected at least one single cell. Then compare the obtained SOC difference with the first equalization opening threshold. If the SOC difference of a single battery is greater than or equal to the first equalizing opening threshold, the battery is a single battery that needs to be balanced; if a single battery If the SOC difference is less than the first equalization opening threshold, the battery is a single cell that does not require equalization.

The reference SOC value is different, the selected at least one single cell is different, and the process of balancing the single cell that needs to be balanced is different. The following describes the case where the reference SOC value is the minimum value, the maximum value, and the average value among the SOC values of the individual cells in the battery pack.

1) In the case that the reference SOC value is the minimum value among the SOC values of the individual cells in the battery pack, the determining the SOC value of the at least one single cell and the reference SOC value required for the balance judgment; The SOC difference value includes: determining the SOC difference value between the SOC value of the following single battery and the reference SOC value required for the balance judgment:

The single cell with the largest SOC value in the battery pack; or

Other single cells in the battery pack except the single cells whose SOC value is the minimum value.

Correspondingly, after it is determined that the single cell to be balanced is a single cell whose SOC difference is greater than or equal to the first equalization turn-on threshold in the at least one single cell, the method further includes: controlling the at least one single cell The single cells whose SOC difference is greater than or equal to the first equalization turn-on threshold in the single cells are discharged.

Specifically, in the case where the reference SOC value is the minimum value among the SOC values of the individual cells in the battery pack, only the SOC value of the single cell with the largest SOC value in the battery pack can be made to differ from the reference SOC value, and further Determine whether the single cell with the largest SOC value in the battery pack is the single cell that needs to be balanced. This embodiment can only determine whether a single cell needs to be balanced.

In the case where the reference SOC value is the minimum value among the SOC values of the individual cells in the battery pack, the SOC values of other single cells in the battery pack except the single cell with the smallest SOC value can also be compared with the reference SOC values. The SOC value is poor, and then it is judged whether the other single cells in the battery pack except the single cell with the smallest SOC value are the single cells that need to be balanced. This embodiment is a batch judgment method, which can determine at one time whether the other single cells in the battery pack except the single cell with the smallest SOC value are the single cells that need to be balanced.

When the reference SOC value is the minimum value among the SOC values of the individual cells in the battery pack, the process of balancing the single cells that need to be balanced is as follows: passive balancing is adopted regardless of whether the battery pack is in the state of charge or discharge. , to discharge the single cells that need to be balanced.

2) In the case that the reference SOC value is the maximum value among the SOC values of the individual cells in the battery pack, the determining the SOC value of the at least one single cell and the reference SOC value required for the balance judgment; The SOC difference value includes: determining the SOC difference value between the SOC value of the following single battery and the reference SOC value required for the balance judgment:

The single cell with the smallest SOC value in the battery pack; or

Other single cells in the battery pack except the single cells with the SOC value of the maximum value.

Correspondingly, after it is determined that the single cell to be balanced is a single cell whose SOC difference is greater than or equal to the first equalization turn-on threshold in the at least one single cell, the method further includes: controlling the at least one single cell The single cells whose SOC difference is greater than or equal to the first equalization turn-on threshold in the single cells are charged.

Specifically, in the case where the reference SOC value is the maximum value among the SOC values of the individual cells in the battery pack, only the SOC value of the single cell with the smallest SOC value in the battery pack may be differentiated from the reference SOC value, and further Determine whether the single cell with the smallest SOC value in the battery pack is the single cell that needs to be balanced. This embodiment can only determine whether a single cell needs to be balanced.

In the case where the reference SOC value is the maximum value among the SOC values of each single cell in the battery pack, the SOC values of other single cells in the battery pack except the single cell with the largest SOC value can also be compared with the reference SOC value. The SOC value is poor, and then it is judged whether the other single cells in the battery pack except the single cell with the smallest SOC value are the single cells that need to be balanced. This embodiment is a batch judgment method, which can determine at one time whether other single cells in the battery pack except the single cell with the largest SOC value are single cells that need to be balanced.

When the reference SOC value is the maximum value among the SOC values of each single cell in the battery pack, the process of balancing the single cells that need to be balanced is: whether the battery pack is in the charging state or the discharging state, active balancing is adopted. , to charge the single battery that needs to be balanced.

3) In the case where the reference SOC value is the average value of the SOC values of the individual cells in the battery pack, the determining of the SOC between the SOC value of the at least one single cell and the reference SOC value required for the balance judgment The difference value includes: determining the SOC difference value between the SOC value of each single cell in the battery pack and the reference SOC value.

Correspondingly, after determining that the single cells to be equalized are the single cells whose SOC difference is greater than or equal to the first equalization turn-on threshold in the at least one single cell, the method further includes:

For any single cell whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single cell, when the SOC value of the single cell is greater than the reference SOC value, control the single cell discharging, and, when the SOC value of the single cell is less than the reference SOC value, controlling the single cell to charge.

Specifically, in the case where the reference SOC value is the average value of the SOC values of each single cell in the battery pack, the SOC value of each single cell in the battery pack can be made to differ from the reference SOC value, and then it is determined that each cell in the battery pack is different from the reference SOC value. Whether the single cell is a single cell that needs to be balanced. This embodiment is a batch judgment method, which can determine at one time whether each single cell in the battery pack is a single cell that needs to be balanced.

In the case where the reference SOC value is the average value of the SOC values of the individual cells in the battery pack, the process of balancing the single cells to be balanced is as follows: no matter the battery pack is in the state of charge or discharge, the process of balancing the single cells to be balanced is as follows: The single cells whose SOC value in the bulk battery is greater than the average value are all passively balanced, and the single cells whose SOC value is greater than the average value in the single cell that needs to be balanced are discharged; the single cell whose SOC value needs to be balanced are less than The single cells with the average value are all actively balanced, and the single cells whose SOC value is less than the average value in the single cells that need to be balanced are charged.

Optionally, in combination with the above embodiments, the method further includes:

For any single cell whose SOC difference in the at least one single cell is greater than or equal to the first equalization turn-on threshold, determine the SOC value of the single cell according to the SOC value of the single cell and the reference SOC value. target equilibrium duration;

According to the target equalization duration of the single cell, the equalization of the single cell is controlled.

After the single cells to be balanced are determined, the target equalization duration of the single cells to be balanced can also be determined, and then the single cells to be balanced are balanced according to the determined target equalization duration. The determination of the target equalization duration is determined according to the SOC value of the single battery to be equalized and the reference SOC value.

Optionally, according to the SOC value of the single battery to be balanced and the reference SOC value, the target balancing duration of the single battery to be balanced is determined, and there are but are not limited to the following two determination methods:

1) The first determination method includes the following steps:

Determine the power difference according to ΔQ=ΔSOC×C _n , where ΔQ is the power difference, ΔSOC is the SOC difference between the SOC value of the single cell to be balanced and the reference SOC value, and C _n is the available capacity of the single cell to be balanced ; Determine the target equalization duration according to t=ΔQ/I, where t is the target equalization duration, and I is the equalization current of the single cell to be equalized.

2) The second determination method includes the following steps:

According to the SOC difference between the SOC value of the single battery to be balanced and the reference SOC value, and the corresponding relationship between the preset SOC difference value and the target balancing duration, determine the SOC of the single battery to be balanced. Target Equilibrium Duration.

In an embodiment of the present disclosure, the corresponding relationship between the SOC difference and the target equalization duration is obtained through measurement. After obtaining the SOC difference between the SOC value of the single battery to be balanced and the reference SOC value, the corresponding relationship between the SOC difference and the target balancing duration can be inquired, and the target balancing duration can be determined.

Next, the case where the load voltage difference is selected to determine the single cells to be balanced will be described. Specifically include the following steps:

According to the load voltage value of each single cell in the battery pack, determine the reference load voltage value required for the balance judgment;

determining a load voltage difference between the load voltage value of the at least one single cell and the reference load voltage value;

According to the load voltage difference and the second equalization opening threshold, it is determined that the single cells to be equalized are the single cells whose load voltage difference is greater than or equal to the second equalization opening threshold in the at least one single cell.

The description of the reference load voltage value required for the balance judgment is similar to the description of the reference SOC value required for the balance judgment with reference to the previous description. The reference load voltage value may be the load voltage value of any single cell in the battery pack. For example: the load voltage value of the single cell with the largest load voltage value in the battery pack, or the load voltage value of the single cell with the smallest load voltage value in the battery pack, or the load voltage value of the cell with the highest load voltage value in the battery pack The load voltage value of the bulk battery (for the case where the battery pack includes an odd number of single cells).

The reference load voltage value can also be calculated according to the load voltage value of each single cell in the battery pack, for example: the average value of the load voltage value of each single cell in the battery pack, or the row of load voltage values in the battery pack. The average value of the load voltage values of the two cells in the middle (for the case where the battery pack includes an even number of cells).

The second equalization opening threshold and the first equalization opening threshold may be the same or different. Both are thresholds used to determine whether to turn on balancing for any single cell in the battery pack, that is, thresholds for judging whether any single cell in the battery pack is a single cell that needs to be balanced.

First, select at least one single cell from the battery pack, and then make a difference between the load voltage value of the selected at least one single cell and the reference load voltage value to obtain the load voltage difference of the selected at least one single cell. Then compare the obtained load voltage difference with the second equalization turn-on threshold. If the load voltage difference of a single cell is greater than or equal to the second equalization turn-on threshold, the battery is a single cell that needs to be balanced; If the load voltage difference of the bulk battery is smaller than the second equalization turn-on threshold, the battery is a single cell that does not require equalization.

The reference load voltage value is different, the selected at least one single cell is different, and the process of balancing the single cell that needs to be balanced is different. The following describes the case where the reference load voltage value is the minimum value, the maximum value, and the average value among the load voltage values of the individual cells in the battery pack.

1) In the case that the reference load voltage value is the minimum value among the load voltage values of the individual cells in the battery pack, the determination of the load voltage value of the at least one single cell and the reference load voltage required for the balance judgment The load voltage difference between the values includes: determining the load voltage difference between the load voltage value of the following single battery and the reference load voltage value required for the balance judgment:

The single cell with the largest load voltage value in the battery pack; or

Other single cells in the battery pack except the single cells whose load voltage value is the minimum value.

Correspondingly, after determining that the single cell to be balanced is a single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell, the method further includes: controlling the at least one single cell A single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in one single cell is discharged.

Specifically, in the case where the reference load voltage value is the minimum value among the load voltage values of the individual cells in the battery pack, only the load voltage value of the single cell with the largest load voltage value in the battery pack can be compared with the reference load voltage value Make a difference in the value, and then judge whether the single cell with the largest load voltage value in the battery pack is the single cell that needs to be balanced. This embodiment can only determine whether a single cell needs to be balanced.

In the case where the reference load voltage value is the minimum value among the load voltage values of the individual cells in the battery pack, the load voltages of other single cells in the battery pack other than the single cell with the smallest load voltage value can also be value, and make a difference with the reference load voltage value, and then judge whether other single cells in the battery pack except the single cell with the smallest load voltage value are the single cells that need to be balanced. This embodiment is a batch judgment method, which can determine at one time whether other single cells in the battery pack except the single cell with the smallest load voltage value are single cells that need to be balanced.

In the case where the reference load voltage value is the minimum value among the load voltage values of the individual cells in the battery pack, the process of balancing the single cells to be balanced is as follows: regardless of whether the battery pack is in the charging state or the discharging state, use the Passive equalization, discharges the cells that need equalization.

2) In the case that the reference load voltage value is the maximum value among the load voltage values of each single cell in the battery pack, the determining of the load voltage value of the at least one single cell and the reference load voltage required for the balance judgment The load voltage difference between the values includes: determining the load voltage difference between the load voltage value of the following single battery and the reference load voltage value required for the balance judgment:

The single cell with the smallest load voltage value in the battery pack; or

Other single cells in the battery pack except the single cells whose load voltage value is the maximum value.

Correspondingly, after determining that the single cell to be balanced is a single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell, the method further includes: controlling the at least one single cell A single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in one single cell is charged.

Specifically, when the reference load voltage value is the maximum value among the load voltage values of the individual cells in the battery pack, only the load voltage value of the single cell with the smallest load voltage value in the battery pack can be compared with the reference load voltage value Make a difference to the value, and then judge whether the single cell with the smallest load voltage value in the battery pack is the single cell that needs to be balanced. This embodiment can only determine whether a single cell needs to be balanced.

In the case where the reference load voltage value is the maximum value among the load voltage values of the individual cells in the battery pack, the load voltages of other single cells in the battery pack except the single cell with the largest load voltage value can also be set to value, and make a difference with the reference load voltage value, and then judge whether other single cells in the battery pack except the single cell with the smallest load voltage value are the single cells that need to be balanced. This embodiment is a batch judgment method, which can determine at one time whether other single cells in the battery pack except the single cell with the largest load voltage value are the single cells that need to be balanced.

When the reference load voltage value is the maximum value among the load voltage values of the individual cells in the battery pack, the process of balancing the single cells that need to be balanced is as follows: regardless of whether the battery pack is in the charging state or the discharging state, use the Active equalization, charging single cells that need equalization.

3) In the case that the reference load voltage value is the average value of the load voltage values of the individual cells in the battery pack, the determination of the load voltage value of the at least one single cell and the reference load voltage value required for the balance judgment The load voltage difference between the two includes: determining the load voltage difference between the load voltage value of each single cell in the battery pack and the reference load voltage value.

Correspondingly, after determining that the single cell to be balanced is the single cell whose load voltage difference in the at least one single cell is greater than or equal to the second equalization turn-on threshold, the method further includes:

For any single cell whose load voltage difference in the at least one single cell is greater than or equal to the second equalization turn-on threshold, when the load voltage value of the single cell is greater than the reference load voltage value, control the The single battery is discharged, and when the load voltage value of the single battery is less than the reference load voltage value, the single battery is controlled to be charged.

Specifically, in the case where the reference load voltage value is the average value of the load voltage values of the individual cells in the battery pack, the load voltage value of each single cell in the battery pack may only be differentiated from the reference load voltage value, and further Determine whether each single cell in the battery pack is a single cell that needs to be balanced. This embodiment is a batch judgment method, which can determine at one time whether each single cell in the battery pack is a single cell that needs to be balanced.

In the case where the reference load voltage value is the average value of the load voltage values of the individual cells in the battery pack, the process of balancing the single cells that need to be balanced is: no matter the battery pack is in a charged state or a discharged state, the balance of the single cells that need to be balanced is as follows: The single cells whose load voltage value is greater than the average value in the single cells that need to be balanced are all passively balanced, and the single cells whose load voltage value is greater than the average value in the single cells that need to be balanced are discharged; Active balancing is adopted for the single cells whose medium load voltage value is less than the average value, and the single cells whose load voltage value is less than the average value among the single cells that need to be balanced are charged.

Optionally, in combination with the above embodiments, the method further includes:

For any single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell, determine the single cell according to the load voltage value of the single cell and the reference load voltage value. The target equalization time of the body battery;

According to the target equalization duration of the single cell, the equalization of the single cell is controlled.

After the single cells to be balanced are determined, the target equalization duration of the single cells to be balanced can also be determined, and then the single cells to be balanced are balanced according to the determined target equalization duration. The determination of the target equalization duration is determined according to the load voltage value of the single battery to be equalized and the reference load voltage value.

Optionally, according to the load voltage value of the single cell to be balanced and the reference load voltage value, the target equalization duration of the single cell to be balanced is determined, and there are but are not limited to the following three determination methods:

1) The first determination method includes the following steps:

Determine a first SOC value corresponding to the reference load voltage value according to the reference load voltage value and the open-circuit voltage OCV of the battery pack - the SOC curve of the remaining power; according to the load voltage value of the single battery to be balanced and the According to the OCV-SOC curve, a second SOC value corresponding to the load voltage value of the single battery to be balanced is determined; the target equalization duration is determined according to the first SOC value and the second SOC value.

Optionally, the determining the first SOC value corresponding to the reference load voltage value according to the reference load voltage value and the open-circuit voltage OCV-remaining power SOC curve of the battery pack includes: placing the load in the battery pack The single battery with the smallest difference between the voltage value and the reference load voltage value is determined as the reference battery; the reference OCV value of the reference battery is determined according to the load voltage value of the reference battery and the internal resistance value of the reference battery; determining the SOC value corresponding to the reference OCV value as the first SOC value according to the reference OCV value and the OCV-SOC curve;

The determining the second SOC value corresponding to the load voltage value of the single battery to be balanced according to the load voltage value of the single battery to be balanced and the OCV-SOC curve includes: according to the single battery to be balanced The load voltage value of the bulk battery and the internal resistance value of the single battery to be balanced are determined to determine the OCV value of the single battery to be balanced; according to the OCV-SOC curve, the OCV value of the single battery to be balanced is determined. The corresponding SOC value is the second SOC value.

In one embodiment of the present disclosure, the OCV-SOC curve is obtained through measurement. For example, for a single battery, in the process of changing its SOC value from 0 to 100%, at every certain SOC value, the open circuit voltage OCV of the battery is measured once, and then the OCV and the corresponding OCV of each point are measured. The SOCs correspond one-to-one to form the SOC-OCV curve of the single battery.

It should be understood that when the open circuit voltage OCV is measured, the load voltage of the single cell can be collected first, and then converted into the corresponding open circuit voltage OCV according to formula (1).

Thus, the first SOC value of the reference battery can be obtained according to the reference voltage value, the internal resistance value of the reference battery, and the OCV-SOC curve corresponding to the reference battery. The second SOC value of the single battery to be balanced is obtained according to the voltage value of the single battery to be balanced, the internal resistance value of the single battery to be balanced, and the OCV-SOC curve corresponding to the single battery to be balanced.

After obtaining the first SOC value and the second SOC value, the following steps are performed:

Determine the power difference according to ΔQ=ΔSOC×C _n , where ΔQ is the power difference, ΔSOC is the SOC difference between the first SOC value and the second SOC value, and C _n is the available capacity of the single battery to be balanced;

The target equalization duration is determined according to t=ΔQ/I, where t is the target equalization duration, and I is the equalization current of the single cell to be equalized.

2) The second determination method includes the following steps:

According to the load voltage difference between the load voltage value of the single cells to be balanced and the reference load voltage value, and the corresponding relationship between the preset load voltage difference and the target balancing duration, the to-be-balanced is determined. The target equilibration time for a single cell.

In an embodiment of the present disclosure, the corresponding relationship between the load voltage difference and the target equalization duration is obtained through measurement. After obtaining the load voltage difference between the load voltage value of the single cell to be balanced and the reference load voltage value, the corresponding relationship between the load voltage difference and the target balancing duration can be queried to determine the target balancing duration.

It should be understood that, referring to Table 1 below, when the battery performance parameters are SOC value, internal resistance value, self-discharge rate, voltage change rate, charge change rate or time change rate, the corresponding relationship table of balance judgment and balance mode.

Among them, the self-discharge rate of the single battery is used to characterize the capacity loss and capacity loss rate of the single battery. In one embodiment, when the battery pack stops working and reaches a stable state (time t1), the open circuit voltage value V1 of each single cell of the battery pack is detected and recorded; when the battery pack starts working again (time t2), Detect and record the open-circuit voltage value V2 of each single cell of the battery pack; calculate the self-discharge rate η of each single cell according to the open-circuit voltage value of each single cell obtained by the two detections, and the calculation method of the self-discharge rate value η is as follows: :

(1) Based on the OCV-SOC curve of the battery, find the corresponding SOC1 and SOC2 according to the detected V1 and V2;

(2) Calculate the SOC change value ΔSOC of the battery according to SOC1 and SOC2;

(3) Calculate the battery capacity released by the battery self-discharge according to ΔSOC and the battery full capacity C, ΔQ=ΔSOC*C;

(4) Calculate the value of the battery self-discharge rate η: η=ΔQ/(t1-t2).

The voltage change rate of the single cell may be the amount of voltage change when the specified physical quantity of the single cell changes in units. For example, in the present disclosure, the voltage variation (dv/dq) of a single battery is used to charge or discharge a preset amount of power to a single battery; The amount (dv/dt) is used as an example for description.

The power change rate (dq/dv) of the single battery can be the amount of power change when the specified physical quantity of the single battery changes in units. For example, the present disclosure takes the amount of electricity that needs to be charged when the voltage of a single cell increases from the initial voltage by one unit voltage, or the amount of electricity that is reduced when the voltage of the single battery decreases from the initial voltage by one unit voltage.

The time rate of change (dt/dv) of a single cell may be the time period required for a unit change in a specified physical quantity of a single cell. For example, the present disclosure takes the charging time required for the voltage of a single cell to rise from the initial voltage by one unit voltage, or the discharge time required for the voltage of the single cell to drop from the initial voltage by one unit voltage as an example.

Table 1

Therefore, when different battery performance parameters are used for balancing judgment, the judgment is made according to the corresponding balancing judging method in Table 1, and the single cells in the battery pack that need to be balanced are determined.

It should be understood that, if it is determined that there is no single cell that needs to be balanced, it is continued to determine whether there is a single cell that needs to be balanced according to the SOC value of at least one single cell in the battery pack. When it is determined that there is no single cell that needs to be equalized, the control module may not perform any action, so that the equalization module corresponding to any battery is not turned on.

Referring to FIG. 8 , it is a schematic diagram of an equalization module according to an embodiment of the present disclosure. Controlling the equalization of the single cells to be equalized needs to be carried out in combination with the above-mentioned equalization judgment. According to the steps of equalization judgment, determine whether the equalization mode of the single cells to be equalized is passive equalization (that is, to discharge the single cells to be equalized) or active equalization (that is, to charge the single cells to be equalized), and turn on the corresponding equalization module .

Referring to FIG. 8 , for passive equalization, the equalization module includes: a resistor 811 , and each single cell corresponds to one equalization module, that is, two ends of each single cell are connected in parallel with a resistor.

For the single cell to be balanced that needs to be passively balanced, the control module controls the parallel loop between the single cell to be balanced and its corresponding resistance to conduct, so as to perform passive balance of the single cell. Referring to FIG. 8 , the control module controls the conduction of the switch module 812 to realize conduction of the parallel circuit between the single cells to be balanced and their corresponding resistances.

The resistor 811 can be a fixed value resistor or a variable resistor. In one embodiment, the resistor 811 can be a thermistor with a positive temperature coefficient, which can change with the change of temperature, so that the balancing current generated during balancing can be adjusted, so as to automatically adjust the heating value of the battery balancing system, and finally adjust the balancing current of the battery balancing system. The temperature of the cell balancing system is effectively controlled.

Referring to FIG. 8, for active balancing, the balancing module includes a charging branch 94 connected in parallel with each single cell 95 in the battery pack, the charging branch 94 corresponds to the single cell 95 one-to-one, and each charging branch 94 Both are connected to the generator 92, and the generator 92 and the engine 91 are mechanically connected through gears.

For a single battery to be balanced that needs to be actively balanced, the control module controls the charging branch 94 corresponding to the single battery to be balanced to conduct. When the engine 91 rotates, the generator 92 is driven to generate electricity, so that the electricity generated by the generator 92 is sent to the single battery to be balanced, so that the electricity of the single battery to be balanced increases.

Referring to FIG. 8 , when the generator 92 is an alternator, the equalization module further includes a rectifier 93 connected in series with the generator 92 , and each charging branch 130 is connected in series with the rectifier 132 . After the rectifier 93 converts the alternating current generated by the generator 92 into direct current, the generator 92 can be used to charge the single battery to be balanced.

Referring to FIG. 8 , the control module can conduct active balancing of the single cells to be balanced by controlling the switches 96 corresponding to the single cells to be balanced to be turned on, so that the charging branches corresponding to the single cells to be balanced are turned on.

In other embodiments, in addition to using the generator to charge the single cells as shown in FIG. 8 , the single cells to be balanced can also be charged through the starter battery in the vehicle.

In another embodiment, in addition to the parallel resistor and the single battery to be balanced as shown in FIG. 8 , the single battery to be balanced can also be connected in parallel with the starting battery of the vehicle to charge the electricity discharged from the single battery to be balanced. Enter the starting battery to achieve the balance of the single battery to be balanced while effectively avoiding the waste of energy.

As described above, in the embodiments of the present disclosure, a plurality of single cells may share one balancing module. When at least two single cells of the multiple single cells sharing a single balancing module need to be balanced, the balancing module and the balancing module need to be balanced. Each of the at least two single cells that need to be balanced is alternately connected and balanced separately.

Correspondingly, an embodiment of the present disclosure further provides a vehicle, including the above-mentioned battery balancing system.

Correspondingly, an embodiment of the present disclosure further provides a computer-readable storage medium, on which computer program instructions are stored, and when the program instructions are executed by a processor, the above-mentioned battery balancing method is implemented.

Correspondingly, an embodiment of the present disclosure further provides an electronic device, including: the aforementioned computer-readable storage medium; and one or more processors configured to execute a program in the computer-readable storage medium.

The preferred embodiments of the present disclosure have been described above in detail with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details of the above-mentioned embodiments. Various simple modifications can be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure. These simple modifications all fall within the protection scope of the present disclosure.

In addition, it should be noted that each specific technical feature described in the above-mentioned specific implementation manner may be combined in any suitable manner under the circumstance that there is no contradiction. In order to avoid unnecessary repetition, various possible combinations are not described in the present disclosure.

Claims (44)

1. A battery balancing method, comprising: Obtain the SOC value of at least one single cell in the battery pack; According to the SOC value of at least one single cell in the battery pack and three intervals of (0, SOC1), (SOC1, SOC2) and (SOC2, 100%), determine where the SOC value of the at least one single cell is located range; According to the interval in which the SOC value of the at least one single battery is located, determine to use the SOC difference value or the load voltage difference value to determine the single battery that needs to be balanced; The determining and using the SOC difference value or the load voltage difference value to determine the single battery to be balanced according to the interval in which the SOC value of at least one single cell in the battery pack is located includes: When the number of the SOC values of the individual cells in the battery pack belonging to the interval (0, SOC1) is greater than or equal to the first preset value, it is determined to use the load voltage difference to determine the single cells that need to be balanced; When the number of SOC values belonging to the interval (SOC1, SOC2) among the SOC values of each single cell in the battery pack is greater than or equal to the second preset value, it is determined to use the SOC difference value to determine the single cells that need to be balanced; When the number of SOC values belonging to the interval (SOC2, 100%) of the SOC values of the individual cells in the battery pack is greater than or equal to the third preset value, it is determined to use the load voltage difference to determine the cells that need to be balanced Battery; or, The determining and using the SOC difference value or the load voltage difference value to determine the single battery to be balanced according to the interval in which the SOC value of at least one single cell in the battery pack is located includes: determining a reference SOC value required for equalization according to the SOC value of at least one single cell in the battery pack; When the reference SOC value belongs to the interval (SOC1, SOC2), it is determined to use the SOC difference value to determine the single cells that need to be balanced; otherwise, it is determined to use the load voltage difference to determine the single cells to be balanced. 2. The method according to claim 1, wherein the method further comprises: The value of SOC1 and the value of SOC2 are determined according to the corresponding relationship between the open circuit voltage OCV of the single battery and the SOC. 3. The method according to claim 2, characterized in that the correspondence between OCV and SOC satisfies: the rate of change of OCV with SOC in the interval (SOC1, SOC2) is less than a specified value, and in the interval (0, SOC1) and the interval The rate of change of (SOC2, 100%) is greater than or equal to the specified value. 4. The method according to claim 1, wherein the determining a reference SOC value required for equalization according to the SOC value of at least one single cell in the battery pack comprises: The SOC value of any single cell in the battery pack is determined as the reference SOC value. 5 . The method according to claim 3 , wherein the specified value is the sampling accuracy of the voltage. 6 . 6 . The method according to claim 1 , wherein when it is determined that the SOC difference is used to determine the single cells that need to be balanced, the method further comprises: 7 . Obtain the reference SOC value required for equilibrium; determining the SOC difference between the SOC value of the at least one single cell and a reference SOC value required for equalization, wherein the reference SOC value required for equalization is determined according to the SOC value of each single cell in the battery pack of; According to the SOC difference value and the first equalization opening threshold, it is determined that the single cells to be equalized are the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single battery. 7. The method according to claim 6, wherein the reference SOC value is a minimum value among the SOC values of each single cell in the battery pack; The determining of the SOC difference between the SOC value of the at least one single battery and the reference SOC value required for equalization includes: Determine the SOC difference between the SOC values of the following cells and the reference SOC value required for equalization: The single cell with the largest SOC value in the battery pack; or Other single cells in the battery pack except the single cells whose SOC value is the minimum value. 8 . The method according to claim 7 , wherein after determining that the single cells to be equalized are the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single cell. 9 . , the method also includes: Controlling the discharge of the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single cell. 9 . The method according to claim 6 , wherein the reference SOC value is the maximum value among the SOC values of the individual cells in the battery pack; 9 . The determining of the SOC difference between the SOC value of the at least one single battery and the reference SOC value required for equalization includes: Determine the SOC difference between the SOC values of the following cells and the reference SOC value required for equalization: The single cell with the smallest SOC value in the battery pack; or Other single cells in the battery pack except the single cells with the SOC value of the maximum value. 10 . The method according to claim 9 , wherein after determining that the single cells to be equalized are the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single cell. 11 . , the method also includes: Controlling the charging of the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single cell. 11. The method according to claim 6, wherein the reference SOC value is an average value of the SOC values of the individual cells in the battery pack; The determining of the SOC difference between the SOC value of the at least one single battery and the reference SOC value required for equalization includes: A SOC difference between the SOC value of each single cell in the battery pack and the reference SOC value is determined. 12 . The method according to claim 11 , wherein after determining that the single cells to be equalized are the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single cell. 13 . , the method also includes: For any single cell whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single cell, when the SOC value of the single cell is greater than the reference SOC value, control the single cell discharging, and, when the SOC value of the single cell is less than the reference SOC value, controlling the single cell to charge. 13 . The method according to claim 6 , wherein after determining that the single cells that need to be balanced are the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single cell. 14 . , the method also includes: For any single cell whose SOC difference in the at least one single cell is greater than or equal to the first equalization turn-on threshold, determine the SOC value of the single cell according to the SOC value of the single cell and the reference SOC value. target equilibrium duration; According to the target equalization duration of the single cell, the equalization of the single cell is controlled. 14. The method according to claim 1, wherein when it is determined that the load voltage difference is used to determine the single cells that need to be balanced, the method further comprises: Determine the reference load voltage value required for balancing according to the load voltage value of each single cell in the battery pack; determining a load voltage difference between the load voltage value of the at least one single cell and the reference load voltage value; According to the load voltage difference and the second equalization opening threshold, it is determined that the single cells to be equalized are the single cells whose load voltage difference is greater than or equal to the second equalization opening threshold in the at least one single cell. 15 . The method according to claim 14 , wherein the reference load voltage value is a minimum value among load voltage values of each single cell in the battery pack; 15 . The determining of the load voltage difference between the load voltage value of the at least one single cell and the reference load voltage value includes: Determine the load voltage difference between the load voltage value of the following single cell and the reference load voltage value: The single cell with the largest load voltage value in the battery pack; or Other single cells in the battery pack except the single cells whose load voltage value is the minimum value. 16 . The method according to claim 15 , wherein, when determining that the single cells to be equalized are the single cells whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell. 17 . Afterwards, the method further includes: Controlling the discharge of a single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell. 17 . The method according to claim 14 , wherein the reference load voltage value is a maximum value among load voltage values of each single cell in the battery pack; 17 . The determining of the load voltage difference between the load voltage value of the at least one single cell and the reference load voltage value includes: Determine the load voltage difference between the load voltage value of the following single cell and the reference load voltage value: The single cell with the smallest load voltage value in the battery pack; or Other single cells in the battery pack except the single cells whose load voltage value is the maximum value. 18 . The method according to claim 17 , wherein, when determining that the single cells that need to be balanced are the single cells whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell. 19 . Afterwards, the method further includes: Controlling the charging of a single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell. 19 . The method according to claim 14 , wherein the reference load voltage value is an average value of the load voltage values of the individual cells in the battery pack; 19 . The determining of the load voltage difference between the load voltage value of the at least one single cell and the reference load voltage value includes: A load voltage difference between the load voltage value of each single cell in the battery pack and the reference load voltage value is determined. 20 . The method according to claim 19 , wherein, when determining that the single cells to be equalized are the single cells whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell. 21 . Afterwards, the method further includes: For any single cell whose load voltage difference in the at least one single cell is greater than or equal to the second equalization turn-on threshold, when the load voltage value of the single cell is greater than the reference load voltage value, control the The single battery is discharged, and when the load voltage value of the single battery is less than the reference load voltage value, the single battery is controlled to be charged. 21 . The method according to claim 14 , wherein, when determining that the single cell to be balanced is a single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell. 22 . Afterwards, the method further includes: For any single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell, determine the single cell according to the load voltage value of the single cell and the reference load voltage value. The target equalization time of the body battery; According to the target equalization duration of the single cell, the equalization of the single cell is controlled. 22. The method according to claim 1, wherein the method for calculating the SOC value comprises a first calculation method and a second calculation method, and the first calculation method corresponds to an interval (0, SOC1) and an interval (SOC2, 100%), the second calculation method corresponds to the interval (SOC1, SOC2); The acquiring the SOC value of each single cell in the battery pack includes: For any single cell in the battery pack, determine the SOC value of the single cell according to the first calculation method; When the SOC value determined according to the first calculation method belongs to the interval (SOC1, SOC2), the SOC value of the single battery is re-determined according to the second calculation method. 23 . The method according to claim 22 , wherein the first calculation method is the method used to calculate the SOC value of the single battery last time. 24 . 24. The method according to claim 22 or 23, wherein the first calculation method is the ampere-hour integration method or the ampere-hour integration combined with the voltage correction method, and the second calculation method is the ampere-hour integration method and the ampere-hour integration method The time integration is combined with a calculation method different from the first calculation method in the voltage correction method. 25. A battery balancing system, comprising: Equalization module, acquisition module and control module, The acquisition module is used to acquire the SOC value of at least one single cell in the battery pack; The control module is configured to determine the SOC value of the at least one single cell in the battery pack according to the SOC value of the at least one single cell and three intervals (0, SOC1), (SOC1, SOC2) and (SOC2, 100%). The interval in which the SOC value is located, and, according to the interval in which the SOC value of the at least one single battery is located, it is determined to use the SOC difference value or the load voltage difference value to determine the single battery that needs to be balanced; The equalization module is used to equalize the single cells that need to be equalized; The control module is used for: When the number of the SOC values of the individual cells in the battery pack belonging to the interval (0, SOC1) is greater than or equal to the first preset value, it is determined to use the load voltage difference to determine the single cells that need to be balanced; When the number of SOC values belonging to the interval (SOC1, SOC2) among the SOC values of each single cell in the battery pack is greater than or equal to the second preset value, it is determined to use the SOC difference value to determine the single cells that need to be balanced; When the number of SOC values belonging to the interval (SOC2, 100%) of the SOC values of the individual cells in the battery pack is greater than or equal to the third preset value, it is determined to use the load voltage difference to determine the cells that need to be balanced Battery; or, The control module is used for: determining a reference SOC value required for equalization according to the SOC value of at least one single cell in the battery pack; When the reference SOC value belongs to the interval (SOC1, SOC2), it is determined to use the SOC difference value to determine the single cells that need to be balanced; otherwise, it is determined to use the load voltage difference to determine the single cells to be balanced. 26. The battery balancing system according to claim 25, wherein the control module is used for: The value of SOC1 and the value of SOC2 are determined according to the corresponding relationship between the open circuit voltage OCV of the single battery and the SOC. 27. The battery balancing system according to claim 26, wherein the corresponding relationship between OCV and SOC satisfies: the rate of change of OCV with SOC in the interval (SOC1, SOC2) is less than a specified value, and in the interval (0, SOC1) The rate of change of the sum interval (SOC2, 100%) is greater than or equal to the specified value. 28. The battery balancing system according to claim 25, wherein the control module is configured to: determine the SOC value of any single battery in the battery pack as the reference SOC value. 29. The battery balancing system according to claim 27, wherein the specified value is the sampling accuracy of the voltage. 30. The battery balancing system of claim 25, wherein the control module is configured to: Obtain the reference SOC value required for equilibrium; determining the SOC difference between the SOC value of the at least one single cell and a reference SOC value required for equalization, wherein the reference SOC value required for equalization is determined according to the SOC value of each single cell in the battery pack of; According to the SOC difference value and the first equalization opening threshold, it is determined that the single cells to be equalized are the single cells whose SOC difference is greater than or equal to the first equalization opening threshold in the at least one single battery. 31. The battery balancing system of claim 30, wherein the control module is configured to: For any single cell whose SOC difference in the at least one single cell is greater than or equal to the first equalization turn-on threshold, determine the SOC value of the single cell according to the SOC value of the single cell and the reference SOC value. target equilibrium duration; The equalization module is used for: According to the target equalization duration of the single cell, the single cell is balanced. 32. The battery balancing system of claim 25, wherein the control module is configured to: Determine the reference load voltage value required for balancing according to the load voltage value of each single cell in the battery pack; determining a load voltage difference between the load voltage value of the at least one single cell and the reference load voltage value; According to the load voltage difference and the second equalization opening threshold, it is determined that the single cells to be equalized are the single cells whose load voltage difference is greater than or equal to the second equalization opening threshold in the at least one single cell. 33. The battery balancing system according to claim 32, wherein the reference load voltage value is a minimum value, a maximum value or an average value among the load voltage values of the individual cells in the battery pack. 34. The battery balancing system of claim 32, wherein the control module is configured to: For any single cell whose load voltage difference is greater than or equal to the second equalization turn-on threshold in the at least one single cell, determine the single cell according to the load voltage value of the single cell and the reference load voltage value. The target equalization time of the body battery; The equalization module is used for: According to the target equalization duration of the single cell, the equalization of the single cell is controlled. 35. The battery balancing system of claim 25, wherein: The method for calculating the SOC value includes a first calculation method and a second calculation method, the first calculation method corresponds to the interval (0, SOC1) and the interval (SOC2, 100%), and the second calculation method corresponds to the interval (SOC1) , SOC2); The acquisition module is used for: For any single cell in the battery pack, determine the SOC value of the single cell according to the first calculation method; When the SOC value determined according to the first calculation method belongs to the interval (SOC1, SOC2), the SOC value of the single battery is re-determined according to the second calculation method. 36 . The battery balancing system according to claim 35 , wherein the first calculation method is the method used for calculating the SOC value of the single cell last time. 37 . 37. The battery balancing system according to claim 35 or 36, wherein the first calculation method is the ampere-hour integration method or the ampere-hour integration combined with the voltage correction method, and the second calculation method is the ampere-hour integration method A calculation method different from the first calculation method in the ampere-hour integration combined with the voltage correction method. 38. The battery balancing system according to claim 25, wherein the control module is connected with the acquisition module and the balancing module corresponding to the same single cell through a channel, and the control module is used to determine the relationship with the control module. When the single cells connected to the module do not need to be balanced, the control module is controlled to be connected with the corresponding sampling module; or, The control module is further configured to time-division multiplex the channel when determining that the single battery connected to the control module needs to be balanced. 39. The battery balancing system according to claim 38, wherein the control module comprises a control chip, and the control chip communicates with the acquisition module and the balancer corresponding to the same single cell through one pin and the one channel. Module connection. 40 . The battery balancing system according to claim 25 , wherein the control module is respectively connected to the acquisition module and the balancing module corresponding to the same single cell through two channels. 41 . 41. The battery balancing system according to claim 40, wherein the control module comprises a control chip, and the control chip is respectively connected with the acquisition module and the balancing module corresponding to the same single cell through two pins, The two pins are in one-to-one correspondence with the two channels. 42. A computer-readable storage medium on which computer program instructions are stored, characterized in that, when the program instructions are executed by a processor, the method of any one of claims 1-24 is implemented. 43. An electronic device, characterized in that, comprising: The computer-readable storage medium of claim 42; and One or more processors for executing programs in the computer-readable storage medium. 44. A vehicle, characterized in that the vehicle comprises: a battery pack and the battery balancing system of any one of claims 25-41.

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