WO2019042413A1 - Battery equalization method and system, vehicle, storage medium, and electronic device - Google Patents

Abstract

A battery equalization method and a battery system comprising same, a vehicle, a storage medium, and an electronic device. The equalization method comprises: obtaining, according to battery information of cells in a battery pack obtained within a sampling period of a unit cycle, a state of charge (SOC) value of at least one cell in the battery pack; determining, according to the SOC value of the at least one cell in the battery pack as well as three intervals (0, SOC1), (SOC1, SOC2), and (SOC2, 100%), the interval where the SOC value of the at least one cell is located; accordingly, determining to use a SOC difference or a load voltage difference to determine an equalization duty ratio of a cell needing to be equalized; and controlling the equalization of the cell to be equalized within an equalization period of the unit cycle according to the equalization duty ratio of the cell needing to be equalized. Whereby, battery information acquisition and equalization are performed by time, and therefore, the acquired battery information is more accurate, and the equalization effect is better. Moreover, by performing the equalization according to an equalization duty ratio, the equalization efficiency can be improved.

Description

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

Cross-reference to related applications

The present application is based on a Chinese patent application filed on Jan. 31, 2017, the entire disclosure of which is hereby incorporated by reference.

Technical field

The present application relates to the field of control technologies, and in particular, to a battery equalization 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. A vehicle power battery generally consists of a plurality of single cells connected in series to form a module. With the use of the battery, the difference between the individual cells gradually expands, and the consistency between the 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. The overall capacity is reduced. On the other hand, the gradual enlargement of the differences between the individual cells will cause over-charging of some single cells, over-discharge of some single cells, affecting battery life, damaging the battery, and possibly generating a large amount of heat to cause the battery. Burning or exploding.

Therefore, effective balancing management of the electric vehicle power battery is beneficial to improve the consistency of each battery in the power battery pack, reduce the battery capacity loss, extend the service life of the battery and the driving range of the electric vehicle, and is of great significance.

However, the current battery equalization method may occur while collecting battery information, and is also performing equalization, which may result in inaccurate battery information collected, resulting in poor equalization effect.

Summary of the invention

The purpose of the present application is to provide a battery equalization method, system, vehicle, storage medium, and electronic device to overcome the problems in the related art.

In order to achieve the above object, in a first aspect, the present application provides a battery equalization method, the method comprising:

Obtaining a state of charge SOC of at least one single cell in the battery pack according to battery information of each single cell in the battery group acquired during a sampling period of the unit period, where the unit period includes the sampling period and the equalization period;

Determining, according to an SOC value of at least one of the battery cells in the battery pack and (0, SOC1), (SOC1, SOC2), and (SOC2, 100%), determining an SOC value of the at least one single cell Interval

Determining, by the interval in which the SOC value of the at least one unit cell is located, using an SOC difference value or a load voltage difference value to determine an equalization duty ratio of the unit cells that need to be equalized;

According to the equalization duty ratio of the unit cells that need to be equalized, the equalization of the unit cells that need to be equalized is controlled during the equalization period of the unit period.

In a second aspect, the application provides a battery equalization system, where the system includes: an equalization module, an acquisition module, and a control module;

The collecting module is configured to collect battery information of each single battery of the battery group during the collection period of the unit period under the control of the control module;

The control module is configured to obtain, according to battery information of each single battery in the battery group acquired in a sampling period of a unit period, a state of charge SOC of at least one single battery in the battery group, where the unit period includes the a sampling period and an equalization period; determining the at least one single cell according to SOC values of at least one of the battery cells in the battery pack and three intervals of (0, SOC1), (SOC1, SOC2), and (SOC2, 100%) The interval in which the SOC value of the battery is located; determining, according to the interval in which the SOC value of the at least one unit cell is located, using the SOC difference value or the load voltage difference value to determine an equalization duty ratio of the unit cells that need to be equalized; The equalization duty ratio of the unit cells that need to be equalized, and controlling the equalization of the unit cells that need to be equalized during the equalization period of the unit period;

The equalization module is configured to equalize the corresponding single cells under the control of the control module.

In a third aspect, the present application provides a vehicle comprising the battery equalization system of the above second aspect.

In a fourth aspect, the present application provides a computer readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the method of the first aspect described above.

In a fifth aspect, the application provides an electronic device, including:

a computer readable storage medium according to the fourth aspect;

One or more processors for executing a program in the computer readable storage medium.

Through the above technical solution, battery information collection and equalization are performed in a time-sharing manner, so as to avoid battery information collection and equalization simultaneously, the collected battery information is more accurate and the equalization effect is better; on the other hand, when the single cell requiring equalization is determined After the equalization duty ratio, according to the equalization duty ratio, in the case of setting the unit period, the duration of the acquisition period and the duration of the equalization period are controlled to improve the equalization efficiency and reduce the equalization cost.

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

DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, In the drawing:

1 is a schematic diagram of a battery equalization system according to an embodiment of the present application;

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

3 is a schematic diagram of a battery equalization system according to another embodiment of the present application;

4 is a schematic diagram of a battery equalization system in which two single cells share an equalization module according to another embodiment of the present application;

FIG. 5 is a schematic flow chart of a battery equalization method according to an embodiment of the present application; FIG.

6 is an open circuit voltage OCV-remaining power SOC curve of a single cell according to an embodiment of the present application;

7 is a schematic flow chart of an equalization duty ratio according to a SOC difference according to an embodiment of the present application;

8 is a schematic flow chart of determining an equalization duty ratio of a single cell to be balanced according to a voltage value and a reference voltage value of a single cell that are balanced according to an embodiment of the present application;

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

FIG. 10 is a schematic diagram of a determination process of a single cell requiring equalization according to an embodiment of the present application; FIG.

11 is a schematic flow chart of determining a cell that needs to be equalized according to a voltage in an embodiment of the present application;

FIG. 12 is a schematic diagram of an equalization module according to an embodiment of the present application; FIG.

FIG. 13 is a schematic flowchart of an equalization process according to an embodiment of the present application; FIG.

FIG. 14 is a schematic flowchart of an equalization duration acquisition according to an embodiment of the present application; FIG.

FIG. 15 is a schematic diagram of adjustment of an equalization duty ratio according to an embodiment of the present application.

Detailed ways

The specific embodiments of the present application are described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are intended to be illustrative and not restrictive.

1 is a schematic diagram of a battery equalization system according to an embodiment of the present application. The battery equalization system includes a control module 101, an acquisition module 102, an equalization module 103, and a battery pack 104.

In one embodiment, each unit 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, and the control chip is respectively connected to the acquisition module and the equalization module corresponding to the same single cell through two pins, and the two pins are in one-to-one correspondence with the two channels.

It should be noted that the control channel or channel described in the embodiment of the present application refers to a transmission path of the control command of the control module 101 to the execution end (the acquisition module 102 and the equalization module 103).

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

In one embodiment, referring to Figure 1, each of the cells in the battery is coupled to an acquisition module 102 and an equalization module 103, respectively. If the battery pack includes N single cells, there are N acquisition modules 102 and N equalization modules 103. Thus, the control module 101 passes through 2×N control channels, and each acquisition module and each equalization module respectively. connection.

In other embodiments, different single cells may share an equalization module, for example, N single cells in a battery pack, may share the same equalization module, or each preset number (eg, 2, 3, or 5 equal) single cells share an equalization module and the like. When at least two of the multi-cell cells sharing one equalization module need to be equalized, the equalization module and each of the at least two single cells that need to be equalized are equalized during the equalization period of the unit period. The batteries are connected alternately.

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

FIG. 3 is a schematic structural diagram of a battery equalization system according to another embodiment of the present application.

The battery equalization system includes a control module 301, an acquisition module 302, an equalization module 303, and a battery pack 304. Wherein, the battery pack 304 includes a plurality of unit 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 301 is configured to connect the control module 301 to the corresponding sampling module 302 when it is determined that the battery connected to the control module 301 does not need to be equalized; or the control module 301 is further configured to determine to connect with the control module 301. When the single cells need to be equalized, the acquisition module 302 and the equalization module 303 time-multiplex the control channel 305 according to a unit cycle.

One unit period includes: an acquisition period and an equalization period. The control module 301 controls the acquisition module 302 to sample the battery information of the single battery during the collection period to obtain the battery information of the single battery. The battery information includes at least one of the following: voltage, current, temperature, and the like. In one embodiment, the battery information may include only voltage values, whereby voltage performance parameters 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, thereby obtaining performance parameters such as SOC, internal resistance, and self-discharge rate of the single battery.

The control module 301 determines, according to the battery information of the single battery collected by the collection module 302, a single cell that needs to be balanced and needs to be balanced. For the single cell that needs to be turned on, the control module 301 controls the equalization module corresponding to the single cell that needs to be equalized, and equalizes the cell that needs to be balanced in the equalization period.

Therefore, in the embodiment of the present application, the acquisition module and the equalization module share the same control channel, and the control module controls the acquisition module and the equalization module, and the control channel is time-multiplexed according to the unit period, thereby avoiding battery information collection and equalization. In the process of performing, the influence of the equalization current on the accuracy of the battery information collection; on the other hand, compared with the embodiment shown in FIG. 1 above, the number of channels of the control module chip is reduced, and the hardware cost can be saved.

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 the time-sharing is connected to the acquisition module 302 or the equalization module 303 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 battery during the collection cycle. When the switch K is connected to the equalization module 303, the control module 301 controls the equalization module 303. The corresponding single cells are equalized.

Thus, by setting the switch between the control module and the acquisition module and the equalization module, the control module can achieve the function of acquisition and equalization by adjusting the state of the switch, and can achieve no sampling during equalization, and is unbalanced during sampling. The effect, so that the equalization current does not affect the battery voltage, thus improving the accuracy of the battery voltage sampling.

In one embodiment, as shown in FIG. 3, each of the cells in the battery is connected to an acquisition module 302 and an equalization module 303, respectively. If the battery pack includes N single cells, the number of the acquisition modules 302 is N, and the equalization module 303 is N. Thus, the control module 301 is connected to the acquisition module and the equalization module through N control channels.

In this embodiment of the present application, the acquisition module and the equalization module corresponding to the same single battery share a control channel of the control module, so that the number of channels of the required control module is reduced, thereby reducing the number of channels required for the control module chip.

For example, in the embodiment shown in FIG. 1 , when the acquisition module and the equalization module are respectively connected to the control module through one control channel, the N single cells correspond to 2N control channels. In the embodiment shown in FIG. 3, the acquisition module and the equalization module of the same single battery share a control channel and the control module is connected, and the N single cells correspond to N control channels, thereby reducing the number of control channels. Reduce the cost of the control module.

In the embodiment shown in FIG. 1 , when the acquisition module and the equalization module are respectively connected to the control module through one control channel, the N single cells correspond to 2N control channels, and 2N control channels need to be controlled. In the embodiment shown in FIG. 3, the acquisition module and the equalization module of the same single battery share one control channel of the control module, so that N single cells correspond to N control channels, and only N control channels need to be controlled. This simplifies the control process and reduces the misoperation rate of the control module.

In the embodiment shown in FIG. 1 , when the acquisition module and the equalization module are respectively connected to the control module through a control channel, the N single cells correspond to 2N control channels, and the pass rate of the control module is controlled by the control channel. The pass rate of 2N control channels is determined. In the embodiment shown in FIG. 3, the acquisition module and the equalization module of the same single battery share one control channel of the control module, and the N single cells correspond to N control channels, and the pass rate of the control module is controlled by the control channel. It is determined by the pass rate of the N control channels, which can improve the total pass rate of the plurality of single cells in the whole system through the control channel to the control module, thereby improving the pass rate of the battery equalization system.

In other embodiments, different single cells may share an equalization module, for example, N single cells in a battery pack, may share the same equalization module, or each preset number (eg, 2, 3, or 5 equal) single cells share an equalization module and the like. When at least two of the multi-cell cells sharing one equalization module need to be equalized, the equalization module and each of the at least two single cells that need to be equalized are equalized during the equalization period of the unit period. The batteries are connected alternately.

In an embodiment of the present application, the battery equalization system includes: a battery management controller (BMC) and a plurality of battery information collectors (BICs). In one embodiment, the control module described above is disposed in the battery information collector BIC.

In another embodiment, the control module includes a first control unit disposed in the battery information collector and a second control unit disposed in the battery management controller. The collecting module sends the parameter information of the single battery in the collected battery pack to the second control unit through the first control unit; wherein the collecting module and the equalizing module of the same single battery correspond to one control channel of the first control unit.

The first control unit may be connected to the collection module by controlling the connection channel, thereby controlling the collection module to collect parameter information of the single battery in the battery group. The second control unit may also send an acquisition instruction to the first control unit through the communication unit, so that the connection channel is connected to the collection module by the first control unit.

The first control unit may be connected to the equalization module by controlling the control channel, thereby controlling the equalization module to perform equalization processing on the single battery that needs to be turned on and equalized. The first control unit may send parameter information of the battery pack collected by the acquisition circuit to the second control unit, and the second control unit determines, according to parameter information of the battery pack, a single battery that needs to be turned on, and And transmitting, by the communication unit, an equalization instruction to the first control unit, to control, by the first control unit, that the control channel is connected to the equalization module.

When the acquisition module in the battery equalization system sends the parameter information of the single battery in the collected battery pack to the second control unit through the first control unit, the acquisition module and the equalization module of the same single battery correspond to the first control unit. A connection control channel reduces the number of channels required by the first control unit.

According to an embodiment of the present application, the first control unit of the battery information collector and the second control unit of the battery management controller can selectively perform equalization control on the unit cells that need to be equalized. That is, the first control unit may control the equalization module to perform equalization processing on the unit cells that need to be equalized, and the second control unit may also control the equalization module to perform equalization processing on the unit cells that need to be equalized. The first control unit or the second control unit determines the unit cells that need to be equalized according to the parameter information of the battery pack collected by the collection module.

When the battery information collector does not receive the equalization command sent by the battery management controller, the first control unit receives the parameter information of the battery pack, and determines according to the parameter information of the battery group. When a single battery in the battery pack needs to be turned on, the control equalization module performs equalization processing on the single battery that needs to be turned on.

When the battery information collector receives an instruction for instructing the battery information collector to perform equalization processing, the first control unit receives parameter information of the battery pack, and determines, according to parameter information of the battery pack, When a single battery in the battery pack needs to be turned on, the control equalization module performs equalization processing on the single battery that needs to be turned on.

When the battery information collector receives the battery management controller failure message, the first control unit receives the parameter information of the battery group, and determines, according to the parameter information of the battery group, that the battery group has a single When the battery needs to be turned on, the control equalization module performs equalization processing on the single cells that need to be turned on.

The battery information collector and the battery management controller can selectively control the equalization system through the first control unit and the second control unit, so that one of the battery information collector and the battery management controller can be disabled or malfunctioned. Underneath, the battery balancing system is still guaranteed to operate normally.

Referring to FIG. 4, an exemplary schematic diagram of sharing an equalization module for two single cells is shown. When two cell units sharing one equalization module need to be equalized, the equalization module is alternately connected with each unit cell during the equalization period of the unit period. Alternate connections may be alternate connections at a certain period. Therefore, on the basis of the time-division of the acquisition module and the equalization module, during the equalization period, the single cells sharing the same equalization module are alternately connected with the shared equalization module to achieve equalization.

In one embodiment, the acquisition module can be a voltage acquisition chip for collecting the voltage of the single battery during the acquisition period.

In the embodiment of the present application, the unit period is divided into an acquisition period and an equalization period, and the ratio of the duration of the equalization period to the duration of the unit period is the equalization duty. In the battery equalization method of the embodiment of the present application, after determining the equalization duty ratio of the unit cells that need to be balanced and requiring equalization, the equalization of the cells that need to be balanced is controlled according to the determined equalization duty ratio to improve the equalization. Efficiency and saving on balanced costs.

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

In step S51, the state of charge of the state of charge of at least one of the cells in the battery pack is obtained according to the battery information of each of the cells in the battery segment acquired in the sampling period of the unit cycle, and the unit period includes the sampling period And equalization period;

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

In step S53, determining, according to the interval in which the SOC value of the at least one unit cell is located, using the SOC difference value or the load voltage difference value to determine an equalization duty ratio of the unit cells that need to be equalized;

In step S54, the equalization of the cells requiring equalization is controlled during the equalization period of the unit period according to the equalization duty ratio of the unit cells that need to be equalized. Referring to Fig. 6, there is shown a schematic diagram of an open circuit voltage OCV-SOC curve of a single cell according to an embodiment of the present application. The values of SOC1 and SOC2 can be determined based on the correspondence between the open circuit voltage OCV and the SOC of the unit cells. In one embodiment, the correspondence between the open circuit voltage OCV and the SOC satisfies the rate of change of the OCV with the SOC in the interval (SOC1, SOC2) is less than or equal to a specified value, in the interval (0, SOC1) and (SOC2) , 100%) The rate of change is greater than or equal to the specified value. In one embodiment, the specified value is the sampling accuracy of the voltage.

Referring to FIG. 6, during the charging or discharging of the battery pack, when the SOC value of the single cell is in the interval (0, SOC1) and (SOC2, 100%), the difference in the uniformity of the single cell is evaluated by the voltage difference, And obtain the equilibrium duty ratio of the single cells that need to be balanced. When the SOC value of the single battery is in the interval (SOC1, SOC2), the amount of charge or charge of the single battery is obtained by the ampere-time integration method, thereby determining the real-time SOC value of the single battery, and the SOC value can be avoided by using the voltage. The error brought about can effectively improve the credibility of the SOC. Thus, in this section (SOC1, SOC2), the battery SOC value is used to evaluate the battery uniformity difference, and the equalization duty ratio of the cell to be balanced is obtained. Therefore, in the embodiment of the present application, according to the SOC value of the single battery in the battery pack, it is determined that the SOC difference value or the load voltage difference value is used to determine the equalization duty ratio of the single battery that needs to be balanced, so that the equalization can be more accurately obtained. Duty cycle, reducing the error.

Therefore, in an embodiment of the present application, the step S53 includes: determining that the number of the SOC values of the individual cells in the battery group that belong to the interval (0, SOC1) is greater than or equal to the first preset value. The load voltage difference is used to determine the equalization duty cycle of the cells that need to be equalized.

When the number of SOC values belonging to (SOC1, SOC2) is greater than or equal to a second preset value among the SOC values of the individual cells in the battery pack, it is determined that the SOC difference value is used to determine the equalization of the cells that need to be equalized. Duty cycle.

When the number of SOC values belonging to (SOC2, 100%) is greater than or equal to a third preset value among the SOC values of the individual cells in the battery pack, it is determined that the load voltage difference is used to determine the single cell that needs to be balanced. Equilibrium duty cycle.

In another embodiment of the present application, the foregoing step S53 includes:

Determining a reference SOC value according to an SOC value of at least one of the battery cells in the battery pack;

When the reference SOC value belongs to (SOC1, SOC2), it is determined that the SOC difference value is used to determine an equalization duty ratio of the unit cells that need to be equalized; otherwise, it is determined that the load voltage difference is used to determine the unit cell that needs to be equalized Balanced duty cycle.

Referring to Figure 7, the SOC difference is used to determine the equalization duty cycle of the cells that need to be equalized, including:

In step S71, determining a reference SOC value according to SOC values of respective single cells in the battery pack;

In step S72, determining the SOC difference value between the SOC value of the unit cell that needs to be equalized and the reference SOC value;

In step S73, the power difference is determined according to ΔQ=ΔSOC×C _n , where ΔQ is the power difference, ΔSOC is the unit cell SOC difference that needs to be equalized, and C _n is the unit cell that needs to be balanced. Available capacity;

In step S74, the equalization duty ratio of the unit cells that need to be equalized is determined according to τ=(ΔQ/I)/t, where t is the preset equalization period of the unit cells that need to be equalized, and I is The preset equalization current of the single cell that needs to be equalized, τ is the equalization duty ratio.

In an embodiment, the SOC difference between the SOC value of the unit cell that needs to be equalized and the reference SOC value, and the preset correspondence relationship between the SOC difference value and the equalization duty ratio may also be used to determine the single cell that needs to be equalized. Equilibrium duty cycle.

Referring to Figure 8, the load voltage difference is used to determine the equalization duty cycle of the cells that need to be equalized, including:

In step S81, determining a reference voltage value according to voltage values of respective single cells in the battery pack;

In step S82, the cell having the smallest difference between the voltage value and the reference voltage value in the battery pack is determined as a reference battery;

In step S83, a first SOC value corresponding to the reference value voltage value is determined according to the reference voltage value and an OCV-SOC curve of the reference battery.

In one embodiment, the reference OCV value of the reference battery is determined according to the reference voltage value and the internal resistance value of the reference battery; and then the SOC corresponding to the OCV value is referenced according to the reference OCV value and the OCV-SOC curve of the reference battery The value is determined as the first SOC value.

In step S84, determining a second value corresponding to the voltage value of the unit cell that needs to be equalized according to the voltage value of the unit cell that needs to be equalized and the OCV-SOC curve corresponding to the unit cell that needs to be equalized. SOC value.

In one embodiment, the OCV value of the cell to be balanced is determined according to the voltage value of the cell to be balanced and the internal resistance of the cell to be balanced; and then, the OCV of the cell is balanced according to the need. The SOC curve determines that the SOC value corresponding to the OCV value of the cell to be equalized is the second SOC value.

In step S85, an equalization duty ratio of the unit cells that need to be equalized is determined according to the first SOC value and the second SOC value.

Hereinafter, the process of obtaining the SOC value by the voltage value and the internal resistance value will be described with reference to FIG. 9 and the formula (1):

Referring to FIG. 9 and formula (1), when the battery pack is in a discharged state or a charged state, the battery internal resistance model is adopted, and the single battery is equivalent to an ideal voltage source in series with the resistor R. Then, for a single cell, the sampled voltage value V _L (ie, the load voltage value) of the single cell can be converted into an open circuit voltage value according to formula (1):

OCV=V _L +I×R (1)

Wherein, V _L is a load voltage value collected by the acquisition module during the acquisition period; I is a discharge current or a charging current collected by the acquisition module during the acquisition period; and R is an internal resistance value of the single battery.

The internal resistance of the single cell can be preset. Alternatively, the internal resistance of the unit cell may be determined based on the voltage and capacity of the unit cell. For example, the internal resistance of the unit cell is determined based on the correspondence between the voltage, the capacity, and the internal resistance value of the unit cell. It should be understood that other battery models, such as Thevenin model, PNGV (partnership for a new generation of vehicles) model, etc., can be used to convert the load voltage of the collected single cells. Is the open circuit voltage.

After the open circuit voltage of the single cell is obtained, the SOC value corresponding to the single cell can be obtained according to the OCV-SOC curve of the single cell.

It should be understood that the OCV-SOC curve shown in FIG. 6 can also be converted into a correspondence table of OCV and SOC, an OCV value corresponding to an SOC value, or an OCV range corresponding to an SOC value.

In one embodiment of the present application, an OCV-SOC curve or an OCV-SOC correspondence table is obtained by measurement. For example, for a single cell, in the process of changing its SOC value from 0 to 100%, every time a certain SOC value is separated, the open circuit voltage OCV of the battery is measured once, and then the OCV of each point is corresponding. The SOCs correspond one-to-one to form a SOC-OCV curve or an OCV-SOC correspondence table of the unit cells.

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

Thereby, 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 cell to be balanced is obtained according to the voltage value of the cell to be balanced, the internal resistance of the cell to be balanced, and the OCV-SOC curve corresponding to the cell to be equalized.

Next, determine the difference in charge according to equation (2):

ΔQ=ΔSOC×C _n (2)

Where ΔQ is the difference in electric quantity, ΔSOC is the SOC difference between the first SOC value and the second SOC value, and C _n is the usable capacity of the unit cell to be equalized.

According to formula (3), determine the equilibrium duty ratio of the cells that need to be balanced:

τ=(ΔQ/I)/t (3)

Where t is the preset equalization period of the cell to be balanced, I is the preset equalization current of the cell to be equalized, and τ is the equalization duty. The preset equalization current can be determined according to the resistance of the equalization module, the current that the generator can provide, or the actual equalization requirement.

In the embodiment of the present application, in the embodiment of the present application, initially, for example, when the battery pack is initially charged or discharged, when the first acquisition is performed, the initial equalization duty ratio or the last battery pack stop operation may be used. The equalization duty ratio of the single battery determines the duration of the acquisition period of the unit period and the duration of the equalization period, and collects the battery information of each single battery during the collection period. In one embodiment, the initial equalization duty cycle can be set to zero, ie, only acquisition is performed. After determining the equalization duty ratio of the cell to be equalized, according to the equalization duty ratio, in the case of setting the unit period, the duration of the acquisition period and the duration of the equalization period are controlled to improve the equalization efficiency and reduce Balanced costs.

In an embodiment of the present application, the unit cells that need to be equalized in the above step S3 are determined from the battery pack according to the performance parameters of the individual cells in the battery pack. The performance parameter includes at least one of a voltage, a SOC, an internal resistance, a self-discharge rate, a voltage change rate, a power change rate, and a time change rate.

Referring to FIG. 10, in an embodiment of the present application, a single cell that needs to be equalized is determined by:

In step S101, a difference between a performance parameter of the at least one unit cell and a reference value of the performance parameter is determined.

In step S102, in the at least one single cell, the difference between the performance parameter and the reference value of the performance parameter is greater than or equal to the cell with the equalization on threshold as the cell that needs to be equalized and needs to be equalized.

It should be understood that the equalization on threshold corresponds to the performance parameter.

As described above, when the performance parameter is voltage, the above steps of determining a unit cell requiring equalization, see FIG. 11:

In step S111, a voltage difference between the voltage value of the at least one single cell and the reference voltage value is determined.

In step S112, the single cell in which the voltage difference between the voltage value and the reference voltage value is greater than or equal to the equalization on threshold in at least one of the cells is determined as a cell that needs to be equalized and needs to be equalized.

When the reference voltage value is the minimum value among the voltage values of the individual cells, step S111 includes:

Comparing the voltage value of the single cell having the largest voltage value in the battery pack with the reference voltage value; or the voltage value and the reference voltage value of the single cell other than the single cell except the voltage value in the battery pack Compare.

When the reference voltage value is the minimum value of the voltage values of the individual cells, the subsequent equalization process for the determined cell that needs to be equalized is: controlling the cell discharge requiring equalization to perform passive equalization.

When the reference voltage value is the maximum value among the voltage values of the individual cells, step S111 includes:

Comparing the voltage value of the single cell with the lowest voltage value in the battery pack with the reference voltage value; or the voltage value and the reference voltage value of the single cell other than the single cell in the battery pack except the voltage value being the maximum value Compare.

When the reference voltage value is the maximum value of the voltage values of the individual cells, the subsequent equalization process for the determined cell that needs to be equalized is: controlling the cell charging that needs to be balanced, and performing active equalization.

When the reference voltage value is an average value of the voltage values of the individual cells, step S111 includes:

The voltage values of the individual cells in the battery pack are compared with the reference voltage values, respectively.

When the reference voltage value is an average value of the voltage values of the individual cells, the subsequent equalization process for the determined cell that needs to be equalized is: charging the cell with the control voltage value smaller than the reference voltage value, performing active equalization; The single cell with a voltage value greater than the reference voltage value is discharged, and passive equalization is performed.

It should be understood that, referring to Table 1 below, when the performance parameters are SOC, internal resistance, self-discharge rate, voltage change rate, power change rate or time change rate, respectively, the correspondence table of the balance judgment and the equalization mode.

Among them, the self-discharge rate of the single cell is used to characterize the capacity loss and capacity loss rate of the single cell. In one embodiment, when the battery pack stops working and reaches a steady state (at time t1), the open circuit voltage value V1 of each unit battery of the power battery pack is detected and recorded; when the battery pack starts to start again (t2 time) The open circuit voltage value V2 of each unit battery of the power battery pack is detected and recorded; and the self-discharge rate η of each unit battery is calculated according to the open circuit voltage values of the individual cells obtained by the two tests. The open circuit voltage value can be calculated using the following equation (1).

The voltage change rate of the single cell may be a voltage change rate of the single cell during charging (or discharging), that is, the voltage change rate of the single cell may be a voltage change when the specified physical quantity of the single cell changes. . For example, in the present application, a predetermined amount of electric power is injected or discharged to a single battery, and a voltage variation amount dv/dq of the single battery; or a preset length of charging or discharging the single battery, a voltage variation amount of the single battery dv /dt is an example for explanation.

The rate of change in the amount of electricity (dq/dv) of the unit cell may be the amount of voltage change when the unit of the specified physical quantity of the unit cell changes. For example, in the present application, the amount of electric power required to increase the voltage of the unit cell by one unit voltage from the initial voltage, or the amount of decrease in the voltage of the unit cell from the initial voltage by one unit voltage will be described as an example.

The time change rate (dt/dv) of the unit cell may be the length of time required for the unit change of the specified physical quantity of the unit cell. For example, in the present application, the charging time required for the voltage of the unit cell to rise by one unit voltage from the initial voltage or the discharge time required for the voltage of the unit cell to decrease by one unit voltage from the initial voltage will be described as an example.

Table 1

Therefore, when the equalization judgment is performed using the performance parameters of different batteries, the judgment is made according to the corresponding manner in Table 1, and the unit cell in the battery pack that needs to be equalized is determined in combination with the judgment flow when the performance parameter is the voltage.

It should be understood that if it is determined that there is no single cell that needs to be equalized, the equalization judgment is continued according to the information collected in the next acquisition period. When it is determined that there is no single cell that needs to be equalized according to the information collected during the collection period, during the equalization period, the control module may not operate, so that the equalization modules corresponding to any battery are not turned on.

Equilibrium process

FIG. 12 is a schematic diagram of an equalization module according to an embodiment of the present application. The unit cells that need to be balanced are balanced in the equalization period of the unit period, and need to be combined with the above-mentioned equalization judgment. According to the step of the equalization judgment (as described in the above steps S101 and S102), it is determined that the equalization mode of the unit cells that need to be equalized is passive equalization (ie, discharging the single cells that need to be balanced), or active equalization (ie, for the need) The balanced single cell is charged) and the corresponding equalization module is turned on.

Referring to FIG. 12, for passive equalization, the equalization module includes: a resistor 811, each of which corresponds to an equalization module, that is, a resistor is connected in parallel with each end of each unit cell.

For a cell that needs to be balanced for passive equalization, the control module controls the parallel loop conduction between the cell that needs to be equalized and its corresponding resistor during the equalization period of the unit period to execute the cell. Passive equilibrium. Referring to FIG. 12, the control module is turned on by controlling the switch module 812 to realize conduction of a parallel circuit between the unit cells requiring equalization and their corresponding resistors.

The resistor 811 can be a fixed value resistor or a variable resistor. In one embodiment, the resistor 811 can be a positive temperature coefficient thermistor, which can be varied with temperature, thereby adjusting the equalization current generated during equalization, thereby automatically adjusting the heat generation of the battery equalization system, and finally The temperature of the battery equalization system is effectively controlled.

Referring to FIG. 12, for active equalization, the equalization module includes a charging branch 94 connected in parallel with each of the unit cells 95 in the battery pack. The charging branch 94 is in one-to-one correspondence with the unit cells 95, and each charging branch 94 is provided. Both are coupled to a generator 92 that is mechanically coupled to the engine 91 via a gear.

For a single cell that needs to be actively equalized and needs to be balanced, the control module controls the charging branch 94 corresponding to the cell that needs to be equalized to be turned on. When the engine 91 rotates, the generator 92 is driven to generate electricity, so that the amount of power generated by the generator 92 is supplied to the unit cells that need to be balanced, so that the amount of the cells that need to be balanced is increased.

Referring to Figure 12, when the generator 92 is an alternator, the equalization module further includes a rectifier 93 in series with the generator 92, each of the charging branches 94 being connected in series with the rectifier 93. After the alternating current generated by the generator 92 is converted to direct current by the rectifier 93, the generator 92 can be enabled to charge the unit cells that need to be equalized.

Referring to FIG. 12, the control module can be turned on by controlling the switch 96 corresponding to the unit cell that needs to be equalized, so that the charging branch corresponding to the unit cell that needs to be balanced is turned on, and the active equalization of the unit cells that need to be balanced is performed. .

In other embodiments, in addition to charging the unit cells with a generator as shown in FIG. 12, the unit cells that need to be balanced can be charged by the starter battery in the vehicle.

In another embodiment, in addition to the parallel resistors and the single cells that need to be balanced, as shown in FIG. 12, the cells that need to be balanced can be connected in parallel with the starting battery of the vehicle to discharge the cells that need to be balanced. The power is charged into the starting battery to achieve equalization of the cells that need to be balanced while effectively avoiding waste of energy.

As described above, in the embodiment of the present application, a plurality of single cells can share one equalization module, and when at least two of the multi-cell cells sharing one equalization module need to be equalized, in a unit period During the equalization period, the equalization module is alternately connected with each of the at least two single cells that need to be equalized, and is separately equalized.

In an embodiment of the present application, when the equalized cells are equalized according to the equalization duty ratio, the cumulative equalization time of the cells that need to be equalized is reached to a preset equalization time. Since the duration of a single unit period is limited, the equalization of a unit cell requiring equalization may occur during an equalization period of one or more unit periods.

Referring to FIG. 13, in step S131, the control module controls a control channel of the single cell that needs to be equalized, and equalizes the cells that need to be equalized during the equalization period.

In step S132, when the single equalization period ends, the control module determines whether the equalization of all the cells that need to be equalized is completed, that is, whether the cumulative equalization duration of all the cells that need to be equalized has reached the corresponding preset equalization duration. If the equalization duration of all the cells that need to be balanced has been met, step S134 is performed; if the equalization period of any of the cells requiring equalization does not meet the requirements, step S133 is performed.

When equalizing the cells that need to be equalized in the equalization period, when the cumulative equalization time of any cell that needs to be equalized reaches the corresponding preset equalization duration, the equalization of the cells that need to be balanced is controlled. stop.

In step S133, when the single unit period ends, if the cumulative equalization period of any single cell that needs to be equalized does not reach its corresponding preset equalization duration, after the sampling period of the next unit period ends, within the equalization period Continue to control the equalization of the cells that have not reached the equalization time, and step S132 is performed.

In step S134, a new round of equalization determination is started, and according to the battery information collected during the collection period, the unit cells that need to be equalized need to be equalized and the equalization duty ratio of each unit cell that needs to be balanced is determined.

It should be understood that in the new round of equalization determination, the determination of the unit cells requiring equalization and the determination of the equalization duty ratio of the unit cells requiring equalization may be performed in the manner described above.

For the preset equalization period of the single cell that needs to be equalized in the above embodiment, it may be preset to a fixed value according to the actual equalization requirement, for example, according to the extended variation of the cell difference with time, and the equalization function capability of the system. Request, etc., preset the equalization time to a fixed value. In addition, the preset equalization duration required for the current equalization may be determined according to the historical balance of the unit cells that need to be equalized in the following manner.

Referring to FIG. 14, in step S141, target parameter information of the battery to be equalized is acquired. The target parameters include any of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, power change rate, and time change rate.

In step S142, the historical equalization duration and the historical parameter information of the unit cells that need to be equalized are acquired, and the historical parameter information is historical information of the target parameter information.

In step S143, based on the target parameter information, the historical equalization duration, and the historical parameter information, the equalization duration required for the current equalization of the cells to be equalized is determined. The equalization duration is used as the preset equalization duration.

In one embodiment, the equalization duration is determined using equation (4) below:

Where t _k is the equalization duration; t _k-1 is the historical equalization duration of the previous equalization of the cell to be equalized; ΔS _k is the current time, and the target parameter of the cell to be balanced and the reference value of the target parameter are required The difference between ΔS _k-1 is the difference between the target parameter of the unit cell and the reference value of the target parameter that needs to be equalized at the last equilibrium time; C _k is the current time, and the cell of the equalization is required. Current available capacity; C _k-1 is the last available time, and the historical available capacity of the balanced single cell is required.

Balanced duty cycle adjustment

In an embodiment of the present application, the equalization duty ratio obtained according to the above formula (3) is based on a preset equalization current, and the preset equalization current is determined according to the resistance of the equalization module or the equalization current that the transmitter can provide. of. In the process of actual equalization, as the equalization progresses, the resistance of the resistor affects the equalization current. Therefore, referring to FIG. 15, in an embodiment of the present application, the method further includes: adjusting the equalization duty ratio according to the equalization current:

In step S151, in the equalization process of the unit cells requiring equalization, the equalization current of the unit cells requiring equalization is obtained.

The equalization current can be obtained by adopting the following method: in the equalization loop, a sampling resistor is connected in series, and the voltage across the sampling resistor is detected, and then the equalization current is obtained according to the sampled voltage value and the resistance of the sampling resistor.

In step S152, when the equalization current is greater than or equal to the preset equalization current, the equalization duty ratio of the unit cells that need to be equalized is reduced; or, when the equalization current is less than the preset equalization current, the unit requiring equalization is increased. The equilibrium duty cycle of the battery. In one embodiment, the equalization duty ratio of the unit cells that need to be equalized may be reduced or increased proportionally, for example, the ratio of the obtained equalization current to the preset equalization current is determined, and the equalization duty ratio is determined according to the ratio. Make a decrease or increase.

In one embodiment, the equalization duty of the cell to be equalized can be recalculated according to the equalization current and the above equation (3).

In an embodiment of the present application, in the equalization process of the unit cells that need to be balanced, when any performance parameter of the single cell that needs to be balanced is detected, the equalization duty adjustment condition corresponding to the performance parameter is satisfied. At this time, the equalization duty ratio of the unit cells that need to be balanced is adjusted.

The performance parameters include at least: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, power change rate, and time change rate.

In an embodiment, determining a performance parameter from the foregoing performance parameter as the target performance parameter, when the value of the target performance parameter of the unit cell that needs to be equalized is different from the reference value of the target performance parameter, the balance is started. The difference becomes larger or smaller, and the equalization duty ratio is adjusted.

Adjust the equalization duty cycle, including:

When the difference between the value of the target performance parameter of the unit cell requiring equalization and the reference value of the target performance parameter becomes larger than the difference at the start of the equalization, the adjustment of the equalization duty ratio is increased;

When the difference between the value of the target performance parameter of the unit cell requiring equalization and the reference value of the target performance parameter becomes smaller than the difference at the start of the equalization, the adjustment of the equalization duty ratio is reduced.

In other embodiments, the equalization duty cycle is adjusted, including:

When the battery pack is in a charging state, if the value of the performance parameter of the balanced cell in the equalization process is greater than or equal to the first preset threshold corresponding to the performance parameter, the equalization duty ratio is decreased; or

When the battery pack is in a discharged state, the value of the performance parameter of the balanced single cell in the equalization process is smaller than the second preset threshold corresponding to the performance parameter, and the equalization duty ratio is decreased.

For example, when the performance parameter is voltage, when the battery pack is in the charging state, if the voltage of the single battery during the equalization process is higher than the first preset threshold, the equalization duty ratio is reduced; when the battery pack is at In the discharge state, if the voltage of the single cell during the equalization process is lower than the second predetermined threshold, the equalization duty ratio is decreased.

As above, after the equalization duty ratio is adjusted, in the subsequent equalization period, the equalization is performed according to the adjusted equalization duty ratio.

Correspondingly, the embodiment of the present application further provides a battery equalization system. The battery equalization system comprises: an acquisition module, a control module and an equalization module.

The collecting module is configured to collect battery information of each single battery of the battery pack during the collection period of the unit period under the control of the control module;

a control module, configured to acquire, according to battery information of each single battery in the battery group acquired in a sampling period of the unit period, a state of charge SOC of at least one single battery in the battery group, where the unit period includes a sampling period and an equalization period; Determining an interval in which the SOC value of the at least one single cell is located according to the SOC value of at least one of the battery cells in the battery pack and the three intervals of (0, SOC1), (SOC1, SOC2), and (SOC2, 100%); The interval in which the SOC value of the at least one single cell is located is determined by using the SOC difference value or the load voltage difference value to determine an equalization duty ratio of the unit cells that need to be equalized; according to the equalization duty ratio of the unit cells that need to be balanced, Controlling the equalization of the cells that need to be balanced during the equalization period of the unit period;

The equalization module is configured to equalize the corresponding single cells under the control of the control module.

In one embodiment, the control module is configured to determine, when the number of intervals (0, SOC1) of the SOC values of the individual cells in the battery group is greater than or equal to a first preset value, Determining an equalization duty ratio of the single cells that need to be equalized; when the SOC value of each of the single cells in the battery pack, the number of SOC values belonging to (SOC1, SOC2) is greater than or equal to a second preset value, determining to adopt The SOC difference is used to determine an equalization duty ratio of the unit cells that need to be equalized; when the SOC value of each unit cell in the battery group, the number of SOC values belonging to (SOC2, 100%) is greater than or equal to the third preset At the time of the value, it is determined that the load voltage difference is used to determine the equalization duty ratio of the cells that need to be equalized.

In one embodiment, the control module is configured to determine a reference SOC value according to an SOC value of at least one of the battery cells in the battery pack; when the reference SOC value belongs to (SOC1, SOC2), determine to adopt a SOC difference value to determine an equalization The equilibrium duty cycle of the individual cells; otherwise, the load voltage difference is determined to determine the equalization duty cycle of the cells that need to be equalized.

In one embodiment, the control module is configured to determine a reference SOC value according to the SOC value of each of the single cells in the battery; determine a SOC difference between the SOC value of the unit cell that needs to be equalized and the reference SOC value; ΔQ=ΔSOC×C _n determines the power difference, where ΔQ is the power difference, ΔSOC is the SOC difference of the cell that needs to be equalized, and C _n is the available capacity of the cell that needs to be equalized; according to τ=(ΔQ/I) /t determines the equilibrium duty cycle of the cell to be balanced, where t is the preset equalization time of the cell to be equalized, I is the preset equalization current of the cell requiring equalization, and τ is the equilibrium duty ratio.

In one embodiment, the control module is configured to determine a reference voltage value according to a voltage value of each of the single cells in the battery; and determine, as a reference battery, a single battery that minimizes a difference between the voltage value in the battery and the reference voltage; Determining, according to the reference voltage value and the OCV-SOC curve of the reference battery, a first SOC value corresponding to the reference voltage value; determining, according to the voltage value of the unit cell that needs to be equalized and the OCV-SOC curve corresponding to the cell to be balanced, a second SOC value corresponding to a voltage value of the unit cell to be equalized; determining an equalization duty ratio of the unit cells to be equalized according to the first SOC value and the second SOC value.

In one embodiment, the control module is configured to determine a reference OCV value of the reference battery according to the reference voltage value and the internal resistance value of the reference battery; and the reference OCV value according to the reference OCV value and the OCV-SOC curve of the reference battery The SOC value is determined as the first SOC value;

Determine the OCV value of the cell to be balanced according to the voltage value of the cell to be balanced and the internal resistance of the cell to be balanced; determine the OCV-SOC curve of the cell to be balanced according to the need to balance The SOC value corresponding to the OCV value of the unit cell is the second SOC value.

In one embodiment, a control module is configured to determine a power difference according to ΔQ=ΔSOC×C _n , wherein ΔQ is a power difference, and ΔSOC is a SOC difference between the first SOC value and the second SOC value, and C _n is The available capacity of the cell to be balanced; determine the equalization duty of the cell to be equalized according to τ = (ΔQ / I) / t, where t is the preset equalization time of the cell to be balanced, I For a preset equalization current of a single cell requiring equalization, τ is an equalization duty cycle.

In one embodiment, the control module is further configured to: when the equalization process of the unit cells requiring equalization is performed, when detecting that any one of the performance parameters of the unit cells requiring equalization meets the equalization duty corresponding to the performance parameter When adjusting the conditions, the equalization duty ratio of the single cells that need to be balanced is adjusted, and the performance parameters include at least: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, power change rate, and time change rate.

In one embodiment, the control module is further configured to determine, from the battery pack, a cell that needs to be balanced according to performance parameters of each of the battery cells in the battery pack, wherein the performance parameters include: voltage, SOC, internal resistance, and self At least one of a discharge rate, a voltage change rate, a power change rate, and a time change rate.

In one embodiment, 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 configured to control the control module when it is determined that the single battery connected to the control module does not need to be equalized. Connect to the corresponding sampling module; or,

The control module is further configured to: when the cell connected to the control module needs to be equalized, the acquisition module and the equalization module time division multiplexing channel.

In one embodiment, the control module includes a control chip that is coupled to the acquisition module and the equalization module corresponding to the same single cell through a pin and a channel.

In one embodiment, the control module is respectively connected to the acquisition module and the equalization module corresponding to the same single cell through two channels.

In one embodiment, 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 cell through two pins, and the two pins are in one-to-one correspondence with the two channels.

With regard to the system in the above embodiment, the specific manner in which the respective modules perform the operations has been described in detail in the embodiment relating to the method, and will not be explained in detail herein.

Correspondingly, the embodiment of the present application further provides a vehicle, including the battery equalization system described above.

Correspondingly, the embodiment of the present application further provides a computer readable storage medium, where computer program instructions are stored, and the program instructions are implemented by the processor to implement the battery balancing method described above.

Correspondingly, the embodiment of the present application further provides an electronic device, comprising: the foregoing computer readable storage medium; and one or more processors for executing a program in the computer readable storage medium.

The preferred embodiments of the present application are described in detail above with reference to the accompanying drawings. However, the present application is not limited to the specific details in the foregoing embodiments, and various simple modifications may be made to the technical solutions of the present application within the technical concept of the present application. These simple variations are within the scope of this application.

It should be further noted that the specific technical features described in the above specific embodiments may be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present application will not be further described in various possible combinations.

In addition, any combination of various embodiments of the present application may be made as long as it does not contradict the idea of the present application, and it should also be regarded as the content disclosed in the present application.

Claims (28)

A battery equalization method, comprising: Obtaining a state of charge SOC of at least one single cell in the battery pack according to battery information of each single cell in the battery group acquired during a sampling period of the unit period, where the unit period includes the sampling period and the equalization period; Determining, according to an SOC value of at least one of the battery cells in the battery pack and (0, SOC1), (SOC1, SOC2), and (SOC2, 100%), determining an SOC value of the at least one single cell Interval Determining, by the interval in which the SOC value of the at least one unit cell is located, using an SOC difference value or a load voltage difference value to determine an equalization duty ratio of the unit cells that need to be equalized; According to the equalization duty ratio of the unit cells that need to be equalized, the equalization of the unit cells that need to be equalized is controlled during the equalization period of the unit period. The method according to claim 1, wherein the values of said SOC1 and said SOC2 are determined according to a correspondence relationship between an open circuit voltage OCV of a single cell and SOC. The method according to claim 1 or 2, wherein the correspondence relationship of the OCV with the SOC satisfies the rate of change of the OCV with the SOC in the interval (SOC1, SOC2) is less than a specified value, in the interval ( The rate of change of 0, SOC1) and (SOC2, 100%) is greater than or equal to the specified value. The method of claim 3 wherein said specified value is a sampling accuracy of the voltage. The method according to any one of claims 1 to 4, wherein the determining whether to use the SOC difference value or the load voltage difference to determine the need for equalization according to the interval in which the SOC value of the at least one unit cell is located The balanced duty cycle of the single cell, including: When the number of the SOC values of the individual cells in the battery pack belongs to the interval (0, SOC1) is greater than or equal to the first preset value, it is determined that the load voltage difference is used to determine the equalization duty of the single cells that need to be equalized. ratio; When the number of SOC values belonging to (SOC1, SOC2) is greater than or equal to a second preset value among the SOC values of the individual cells in the battery pack, it is determined that the SOC difference value is used to determine the equalization of the cells that need to be equalized. Duty cycle When the number of SOC values belonging to (SOC2, 100%) is greater than or equal to a third preset value among the SOC values of the individual cells in the battery pack, it is determined that the load voltage difference is used to determine the single cell that needs to be balanced. Equilibrium duty cycle. The method according to claim 1, wherein said determining whether to use the SOC difference value or the load voltage difference value to determine a cell to be balanced is determined according to a section in which the SOC value of said at least one unit cell is located Balanced duty cycle, including: Determining a reference SOC value according to an SOC value of at least one of the battery cells in the battery pack; When the reference SOC value belongs to (SOC1, SOC2), it is determined that the SOC difference value is used to determine an equalization duty ratio of the unit cells that need to be equalized; otherwise, it is determined that the load voltage difference is used to determine the unit cell that needs to be equalized Balanced duty cycle. The method of claim 1 wherein said employing a SOC difference to determine an equalized duty cycle of a unit cell requiring equalization comprises: Determining a reference SOC value according to SOC values of respective single cells in the battery pack; Determining the SOC difference between the SOC value of the unit cell requiring equalization and the reference SOC value; Determining the electric quantity difference according to ΔQ=ΔSOC×C _n , wherein ΔQ is the electric quantity difference, ΔSOC is the unit cell SOC difference value that needs to be equalized, and C _n is the usable capacity of the unit cell that needs to be equalized; Determining an equalization duty ratio of the unit cells that need to be equalized according to τ=(ΔQ/I)/t, where t is a preset equalization period of the unit cells that need to be equalized, and I is the balance that needs to be balanced. The preset equalization current of the single cell, τ is the equalization duty ratio. The method according to any one of claims 1 to 7, wherein the using the load voltage difference to determine an equalization duty ratio of the unit cells requiring equalization comprises: Determining a reference voltage value according to a voltage value of each single battery in the battery pack; Determining, as a reference battery, a single cell that minimizes a difference between a voltage value and a reference voltage value in the battery pack; Determining a first SOC value corresponding to the reference voltage value according to the reference voltage value and an OCV-SOC curve of the reference battery; Determining, according to the voltage value of the unit cell that needs to be equalized and the corresponding OCV-SOC curve of the unit cell that needs to be equalized, a second SOC value corresponding to the voltage value of the unit cell that needs to be equalized; And determining, according to the first SOC value and the second SOC value, an equalization duty ratio of the unit cells that need to be equalized. The method according to claim 8, wherein the determining a first SOC value corresponding to the reference voltage value according to the reference voltage value and an OCV-SOC curve of the reference battery comprises: Determining a reference OCV value of the reference battery according to the reference voltage value and an internal resistance value of the reference battery; Determining, according to the reference OCV value and an OCV-SOC curve of the reference battery, a SOC value corresponding to the reference OCV value as the first SOC value; Determining, according to the voltage value of the unit cell that needs to be equalized and the corresponding OCV-SOC curve of the unit cell that needs to be equalized, a second SOC value corresponding to the voltage value of the unit cell that needs to be balanced, include: Determining an OCV value of the single cell that needs to be equalized according to the voltage value of the unit cell that needs to be equalized and the internal resistance value of the unit cell that needs to be equalized; And determining, according to the OCV-SOC curve of the unit cell that needs to be equalized, that the SOC value corresponding to the OCV value of the unit cell that needs to be equalized is the second SOC value. The method according to claim 9, wherein the determining the equalization duty ratio of the unit cells that need to be equalized according to the first SOC value and the second SOC value comprises: The electric quantity difference is determined according to ΔQ=ΔSOC×C _n , wherein ΔQ is the electric quantity difference, ΔSOC is a SOC difference value between the first SOC value and the second SOC value, and C _n is the required balance The available capacity of the single battery; Determining an equalization duty ratio of the unit cells that need to be equalized according to τ=(ΔQ/I)/t, where t is a preset equalization period of the unit cells that need to be equalized, and I is the balance that needs to be balanced. The preset equalization current of the single cell, τ is the equalization duty ratio. The method according to any one of claims 1 to 10, wherein the method further comprises: In the equalization process of the unit cells that need to be balanced, when it is detected that any one of the performance parameters of the unit cells that need to be balanced satisfies the equalization duty ratio adjustment condition corresponding to the performance parameter, The equalization duty ratio of the cell to be balanced is adjusted, and the performance parameters include at least: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, power change rate, and time change rate. The method according to any one of claims 1 to 11, wherein the method further comprises: Determining the unit cells that need to be equalized from the battery group according to performance parameters of each unit battery in the battery pack, wherein the performance parameters include: voltage, SOC, internal resistance, self-discharge rate, voltage At least one of a rate of change, a rate of change in power, and a rate of change in time. A battery equalization system, comprising: an equalization module, an acquisition module, and a control module; The collecting module is configured to collect battery information of each single battery of the battery group during the collection period of the unit period under the control of the control module; The control module is configured to obtain, according to battery information of each single battery in the battery group acquired in a sampling period of a unit period, a state of charge SOC of at least one single battery in the battery group, where the unit period includes the a sampling period and an equalization period; determining the at least one single cell according to SOC values of at least one of the battery cells in the battery pack and three intervals of (0, SOC1), (SOC1, SOC2), and (SOC2, 100%) The interval in which the SOC value of the battery is located; determining, according to the interval in which the SOC value of the at least one unit cell is located, using the SOC difference value or the load voltage difference value to determine an equalization duty ratio of the unit cells that need to be equalized; The equalization duty ratio of the unit cells that need to be equalized, and controlling the equalization of the unit cells that need to be equalized during the equalization period of the unit period; The equalization module is configured to equalize the corresponding single cells under the control of the control module. The system according to claim 13, wherein the control module is configured to: when the SOC value of each of the single cells in the battery pack belongs to the interval (0, SOC1), the number is greater than or equal to the first preset value. When determining, the load voltage difference is used to determine an equalization duty ratio of the single cells that need to be equalized; when the SOC value of each single battery in the battery pack, the number of SOC values belonging to (SOC1, SOC2) is greater than or equal to When the second preset value is determined, it is determined that the SOC difference value is used to determine an equalization duty ratio of the unit cells that need to be equalized; and when the SOC value of each unit cell in the battery group belongs to the SOC value of (SOC2, 100%) When the number is greater than or equal to the third preset value, it is determined that the load voltage difference is used to determine the equalization duty ratio of the unit cells that need to be equalized. The system according to claim 13 or 14, wherein the control module is configured to determine a reference SOC value according to an SOC value of at least one of the battery cells in the battery pack; when the reference SOC value belongs to ( At SOC1, SOC2), it is determined that the SOC difference is used to determine the equalization duty ratio of the cells that need to be equalized; otherwise, the load voltage difference is determined to determine the equalization duty of the cells that need to be equalized. The system according to any one of claims 13 to 15, wherein the control module is configured to determine a reference SOC value according to an SOC value of each single battery in the battery pack; and determine a single battery that needs to be balanced. a difference between the SOC value and the reference SOC value; determining a power difference according to ΔQ=ΔSOC×C _n , wherein ΔQ is the power difference, and ΔSOC is the unit cell SOC difference that needs to be equalized , C _n is the usable capacity of the unit cell that needs to be equalized; determining an equalization duty ratio of the unit cells that need to be equalized according to τ=(ΔQ/I)/t, where t is the balance required to be balanced The preset equalization period of the single cell, I is the preset equalization current of the single cell that needs to be equalized, and τ is the equalization duty ratio. The system according to any one of claims 13-16, wherein the control module is configured to determine a reference voltage value according to a voltage value of each single battery in the battery pack; and to set a voltage value in the battery pack The single cell having the smallest difference from the reference voltage value is determined as a reference battery; determining a first SOC value corresponding to the reference voltage value according to the reference voltage value and an OCV-SOC curve of the reference battery; A voltage value of the cell to be balanced and an OCV-SOC curve corresponding to the cell to be balanced are determined, and a second SOC value corresponding to the voltage value of the cell to be balanced is determined; according to the first The SOC value and the second SOC value determine an equalization duty ratio of the unit cells that need to be equalized. The system according to claim 17, wherein the control module is configured to determine a reference OCV value of the reference battery according to the reference voltage value and an internal resistance value of the reference battery; An OCV value and an OCV-SOC curve of the reference battery, determining an SOC value corresponding to the reference OCV value as the first SOC value; Determining an OCV value of the unit cell that needs to be equalized according to the voltage value of the unit cell that needs to be equalized and the internal resistance value of the unit cell that needs to be equalized; and OCV of the unit cell according to the need to balance a SOC curve, which determines that the SOC value corresponding to the OCV value of the unit cell requiring equalization is the second SOC value. The system according to claim 18, wherein said control module is configured to determine a power difference according to ΔQ = ΔSOC × C _n , wherein ΔQ is said power difference, and ΔSOC is said first SOC value and said Determining the SOC difference between the second SOC values, C _n is the available capacity of the unit cells that need to be equalized; determining the equalization duty of the unit cells that need to be equalized according to τ=(ΔQ/I)/t Ratio, where t is the preset equalization period of the unit cells that need to be equalized, I is the preset equalization current of the unit cells that need to be equalized, and τ is the equalization duty ratio. The system according to any one of claims 13 to 19, wherein the control module is further configured to detect, when the equalization of the unit cells that need to be balanced, the unit that needs to be balanced When any one of the performance parameters of the battery satisfies the equalization duty adjustment condition corresponding to the performance parameter, the equalization duty ratio of the single cell that needs to be equalized is adjusted, and the performance parameter includes at least: voltage, SOC , internal resistance, self-discharge rate, voltage change rate, power change rate, and time rate of change. The system according to any one of claims 13 to 20, wherein the control module is further configured to determine the need from the battery pack according to performance parameters of each of the battery cells in the battery pack The balanced unit cell, wherein the performance parameter comprises at least one of a voltage, a SOC, an internal resistance, a self-discharge rate, a voltage change rate, a power change rate, and a time change rate. The system according to any one of claims 13 to 21, wherein the control module is connected to an acquisition module and an equalization module corresponding to the same single cell through a channel, and the control module is configured to determine When the single battery connected to the control module does not need to be equalized, the control module is controlled to be connected with the corresponding sampling module; or The control module is further configured to: when the cell connected to the control module needs to be equalized, the acquiring module and the equalization module time-multiplex the channel. The system according to claim 22, wherein said control module comprises a control chip, said control chip being connected to an acquisition module and an equalization module corresponding to the same single cell through a pin and said one channel. The system according to claim 13, wherein the control module is respectively connected to the acquisition module and the equalization module corresponding to the same single cell through two channels. The system according to claim 24, wherein the control module comprises a control chip, and the control chip is respectively connected to an acquisition module and an equalization module corresponding to the same single cell through two pins, the two The pin corresponds to the two channels one by one. A vehicle characterized by comprising the battery equalization system of any of the preceding claims 13-25. A computer readable storage medium having stored thereon computer program instructions, wherein the program instructions, when executed by a processor, implement the method of any of claims 1-12. An electronic device, comprising: The computer readable storage medium of claim 27; One or more processors for executing a program in the computer readable storage medium.

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