WO2019042400A1

WO2019042400A1 - Battery equalization method and system, vehicle, storage medium, and electronic device

Info

Publication number: WO2019042400A1
Application number: PCT/CN2018/103470
Authority: WO
Inventors: 罗红斌; 王超; 沈晓峰; 曾求勇; 刘苑红; 张祥
Original assignee: 比亚迪股份有限公司
Priority date: 2017-08-31
Filing date: 2018-08-31
Publication date: 2019-03-07
Also published as: CN110015187B; CN110015187A

Abstract

A battery equalization method and system, a vehicle, a storage medium, and an electronic device. The method comprises: determining cells needing to be equalized in a battery pack according to cell information of cells of the battery pack obtained within a sampling period of a unit cycle (S51); obtaining, according to the cell information of the cells, values of performance parameters of the cells needing to be equalized and reference values of the performance parameters (S52); determining, according to the values of performance parameters of the cells needing to be equalized, the reference values of the performance parameters, and a preset equalization duty cycle, equalizing current of the cells needing to be equalized (S53); and according to the equalizing current, controlling, within an equalization period of the unit cycle, equalization of the cells needing to be equalized (S54). Therefore, cell information acquisition and equalization can be performed by time; according to the cell information of the cells, the equalizing current of the cells is determined to perform equalization, so that equalization efficiency can be improved.

Description

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

Cross-reference to related applications

The present disclosure claims the priority of the Chinese Patent Application No. "201710775046.4" filed on August 31, 2017 by BYD Co., Ltd., entitled "Battery Equalization Method, System, Vehicle, Storage Medium, and Electronic Device."

Technical field

The present disclosure 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.

At present, how to determine the equalization current well when balancing the battery pack is a problem that needs to be solved.

Summary of the invention

It is an object of the present disclosure to provide a battery equalization method, system, vehicle, storage medium, and electronic device to improve the equalization effect.

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

Determining, in the battery pack, the battery cells in the battery pack that need to be equalized according to the battery information of each of the battery cells of the battery unit acquired during the sampling period of the unit period, where the unit period includes the sampling period and the equalization period;

Obtaining, according to battery information of each unit battery, a value of a performance parameter of the unit cell that needs to be equalized and a reference value of the performance parameter, the performance parameter including at least one of the following parameters: voltage, SOC, and Resistance, self-discharge rate, voltage change rate, power change rate, and time change rate;

Determining, according to the value of the performance parameter of the unit cell that needs to be equalized, the reference value of the performance parameter, and the preset equalization duty ratio, the equalization current of the single cell that needs to be equalized, wherein the equalization accounts for The null ratio is a ratio of the duration of the equalization period to the duration of the unit period;

According to the equalization current, the equalization of the cells requiring equalization is controlled during the equalization period of the unit period.

In a second aspect, a battery equalization system is provided, 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 pack during a sampling period of a unit period under the control of the control module;

The control module is configured to determine, according to battery information of each battery cell of the battery unit acquired in a sampling period of a unit period, the unit cells that need to be balanced in the battery group, where the unit period includes the sampling period and the equalization a period of time; obtaining, according to battery information of each unit battery, a value of a performance parameter of the unit cell to be balanced and a reference value of the performance parameter, the performance parameter being any one of the following parameters: voltage, SOC, Internal resistance, self-discharge rate, voltage change rate, power change rate, and time change rate; reference value of the performance parameter and preset equalization duty ratio according to the value of the performance parameter of the unit cell that needs to be equalized Determining an equalization current of the unit cells that need to be equalized, wherein the equalization duty ratio is a ratio of a duration of the equalization period to a duration of the unit period; and according to the equalization current, in the unit period The equalization period controls the equalization of the unit cells that need to be balanced;

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

In a third aspect, a vehicle is provided, comprising the battery equalization system of the second aspect described above.

A fourth aspect provides a computer readable storage medium having stored thereon computer program instructions, wherein the program instructions are executed by a processor to implement the method of the first aspect described above.

A fifth aspect, an electronic device comprising: the computer readable storage medium of the above fourth aspect; and one or more processors for executing a program in the computer readable storage medium.

Through the above technical solution, battery information collection and equalization and time sharing are performed to avoid battery information collection and equalization at the same time, so the collected battery information is more accurate and the equalization effect is better; on the other hand, the equalization current is based on the performance parameters of the single battery. The value, the reference value of the performance parameter, and the preset equalization duty ratio are determined, thereby performing equalization, which can improve the equalization efficiency of the single cell.

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

DRAWINGS

The drawings are intended to provide a further understanding of the disclosure, and are in the In the drawing:

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

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 disclosure;

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

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

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

6 is a schematic diagram of a determination process of a single cell requiring equalization according to an embodiment of the present disclosure;

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

FIG. 8 is a schematic flow chart of determining an equalization current of a single cell that needs to be equalized according to a voltage value and a reference voltage value of a single cell that needs to be equalized according to an embodiment of the present disclosure; FIG.

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

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

11 is a schematic diagram of an equalization module according to an embodiment of the present disclosure;

12 is a schematic flow chart of an equalization process according to an embodiment of the present disclosure;

FIG. 13 is a schematic flowchart of an equalization duration acquisition 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 is to be understood that the specific embodiments described herein are not to be construed

Before describing the embodiments of the present disclosure in detail, in order to facilitate understanding, the common technical words are first introduced:

The State of Charge (SOC), also known as the remaining charge, indicates the ratio of the remaining capacity of the battery after a period of use or long-term suspension to its fully charged state, expressed as a percentage.

The self-discharge rate, also known as the charge retention capability, refers to the ability of the battery to maintain the power stored under certain conditions under open conditions.

1 is a schematic diagram of a battery equalization system according to an embodiment of the present disclosure. 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 control channels.

The control channel or channel refers to a transmission path of a control command of the control module to the execution end (acquisition module and equalization module).

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, as shown in FIG. 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.

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

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 acquisition module 302 and the equalization module 303 time-multiplex the control channel 305 according to a unit cycle. The control module 301 is configured to control the control channel 305 to connect with the corresponding sampling module when determining that the battery connected to the control module does not need to be equalized; or the control module 301 is further configured to determine the control module When the 301 connected single cells need to be equalized, the acquisition module 302 and the equalization module 303 time-multiplex the channels 305 according to the unit period.

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. Battery information includes at least one of the following: voltage, current, and temperature. 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 the single cells that need to be equalized according to the battery information of the single battery collected by the collection module 302. For the single cell that needs to be turned on, the control module 301 controls the equalization module 303 corresponding to the cell that needs to be equalized, and equalizes the cells that need to be equalized during the equalization period.

Therefore, in the embodiment of the present disclosure, 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 an embodiment, in the control channel shared by the acquisition module 302 and the equalization module 303, a switch K is provided, the control module 301 is connected to the switch K, and the time-sharing and acquisition module 302 or the equalization module 303 is implemented by controlling the switch K. connection. 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 disclosure, the acquisition module and the equalization module corresponding to the same single battery share one 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 a control channel of the control module, so that the N single cells correspond to the N control channels, and only the N control channels need to be controlled. It can simplify the control process and reduce 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 an embodiment of the present disclosure, 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 channel reduces the number of channels required by the first control unit.

According to an embodiment of the present disclosure, the first control unit of the battery information collector and the second control unit of the battery management controller may 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 an embodiment of the present disclosure, 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. The battery equalization method of the embodiment of the present disclosure determines the equalization duty ratio of the unit cells that need to be equalized, and then controls the equalization of the cells that need to be balanced according to the determined equalization duty ratio to improve the equalization efficiency and save the balance. cost.

As an embodiment of the present disclosure, the specific method of the equalization module and the equalization process is as follows:

Method 1: Passive equilibrium.

If the minimum value of the target parameter of each unit cell is used as the reference value of the target parameter, the equalization battery may be equalized by passive equalization, that is, the cell to be equalized is discharged, for example, set and balanced in the equalization module. The parallel resistance of the single cells reduces the difference between the target parameters of the cells to be equalized and the reference value to a preset range, and achieves the effect of equalizing the individual cells in the battery pack.

Method 2: Active balancing.

If the maximum value of the target parameter of each single cell is used as the reference value of the target parameter, the equalization process of the equalized cell may be performed by an active equalization method, that is, the battery to be equalized is charged, for example, a power supply component is set in the equalization module. (such as a generator or a battery), the difference between the target parameter of the unit cell to be equalized and the reference value is reduced to a preset range, and the effect of equalizing each unit cell in the battery pack is achieved.

Method 3: The combination of active and passive equalization.

If the average value or the median of the target parameters of each unit cell is used as the reference value of the target parameter, the unit cell whose target parameter is smaller than the reference value may be subjected to equalization processing in an active equalization manner, and the target parameter is greater than the reference value. The single cell is balanced by a passive equalization method, so that the difference between the target parameter and the reference value of the cell to be balanced is reduced to a preset range, and the effect of equalizing each cell in the battery pack is achieved.

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 disclosure includes:

In step S51, the battery cells in the battery pack that need to be equalized are determined according to the battery information of each of the battery cells of the battery pack acquired in the sampling period of the unit period.

In step S52, a value of a performance parameter of the unit cell to be equalized and a reference value of the performance parameter are obtained according to battery information of each unit battery, and the performance parameter includes at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, power change rate, and time change rate.

In step S53, the equalization current of the cell to be equalized is determined according to the value of the performance parameter of the cell to be equalized, the reference value of the performance parameter and the preset equalization duty.

In step S54, the equalization of the cells requiring equalization is controlled in the equalization period of the unit period in accordance with the equalization current.

Therefore, in the embodiment of the present disclosure, the battery information collection and the equalization and time sharing are performed to avoid the influence of the equalization current on the accuracy of the battery information collection when the battery information collection and equalization are simultaneously performed; on the other hand, according to the battery information of the single battery The equalization current of each single cell is determined to be equalized, and different equalizing currents can be used for different single cells to improve the equalization efficiency of the single cell.

In an embodiment of the present disclosure, the unit cells that need to be equalized 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 the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, power change rate, and time change rate.

Referring to FIG. 6, in an embodiment of the present disclosure, a single cell that needs to be equalized is determined by:

In step S61, 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 S62, the cell in which the difference between the performance parameter and the reference value of the performance parameter is greater than or equal to the equalization on threshold is determined as a cell requiring equalization in at least one of the cells.

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 are shown in FIG. 7:

In step S71, a voltage difference between the voltage value of the at least one single cell and the reference voltage value is determined.

In step S72, 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 is determined as a single cell requiring equalization in at least one of the single cells.

When the reference voltage value is the minimum value among the voltage values of the individual cells, step S71 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 S71 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 voltage values of the individual cells, step S71 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 disclosure, a predetermined amount of power is injected into or discharged from a single battery, and a voltage variation amount dv/dq of the single battery; or a preset duration of charging or discharging the single battery, and a voltage variation amount of the single battery dv /dt is an example for explanation.

The rate of change in the amount of electricity of the unit cell may be the amount of change in voltage when the unit of the specified physical quantity of the unit cell changes. For example, in the present disclosure, 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 electric power of the unit cell reduced by one unit voltage from the initial voltage will be described as an example.

The time rate of change of the unit cells may be the length of time required for the unit of the specified physical quantity of the unit cells to change. For example, in the present disclosure, 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 in step S51 that there is no single cell that needs to be equalized, the determination of the equalization based on the information collected in the next acquisition period is continued. 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.

In an embodiment of the present disclosure, determining, according to the value of the performance parameter of the unit cell that needs to be equalized, the reference value of the performance parameter, and the preset equalization duty ratio, determining the unit cell that needs to be balanced. Equilibrium current, including:

Depending on the difference between the value of the performance parameter of the cell that needs to be equalized and the reference value of the performance parameter, a preset equalization duty cycle, and a preset between the difference and the equalization duty cycle and the equalization current Corresponding relationship, determine the equalization current of the cell that needs to be balanced. For example, when the performance parameter is voltage, the voltage difference between the voltage value of the cell and the voltage reference value, the preset equalization duty ratio, and the voltage difference and the equalization duty ratio and the equalization current are adjusted according to the need. The preset correspondence between the presets determines the equalization current of the unit cells that need to be balanced.

Referring to FIG. 8, in the equalization current determining method of another embodiment of the present disclosure, when the determined performance parameter is a voltage in step S52, step S53 includes:

In step S81, the single cell that minimizes the difference between the voltage value in the battery pack and the reference value of the voltage is determined as the reference battery. The reference value of the voltage is the minimum voltage value, the maximum voltage value or the average voltage value among the voltage values of the individual cells;

In step S82, a first SOC value corresponding to the reference value of the voltage is determined according to the reference value of the voltage and the open circuit voltage OCV-remaining power SOC curve of the reference battery.

In step S83, a second SOC value corresponding to the voltage value of the cell to be equalized is determined according to the voltage value of the cell to be equalized and the OCV-SOC curve corresponding to the cell to be equalized.

In step S84, the equalization current of the unit cell is determined based on the first SOC value, the second SOC value, and the equalization duty ratio.

Referring to FIG. 9, an open circuit voltage OCV-remaining power SOC curve of a single cell according to an embodiment of the present disclosure is shown.

The above step S82 includes:

Determining a reference OCV value of the reference battery according to the reference voltage value and an internal resistance value of the reference battery; and then determining the SOC value corresponding to the reference OCV value as the first SOC according to the reference OCV value and the OCV-SOC curve of the reference battery value.

The above step S93 includes:

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; and then determine the need according to the OCV-SOC curve of the cell to be balanced. The SOC value corresponding to the OCV value of the balanced unit cell is 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. 10 and the formula (1):

Referring to FIG. 10 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 value of the unit cell is determined according to the correspondence relationship 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. 9 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 disclosure, the OCV-SOC curve or 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.

Determine the equalization current of the cell to be balanced according to equation (3):

I=ΔQ/(t×τ) (3)

Where t is the preset equalization period of the cell to be balanced, I is the 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.

Equilibrium process

Referring to FIG. 11 , it is a schematic diagram of an equalization module according to an embodiment of the present disclosure. 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, it is determined that the equalization mode of the unit cells that need to be balanced is passive equalization (that is, discharge of the single cells that need to be balanced), or active equalization (that is, charging the single cells that need to be balanced), and Turn on the corresponding equalization module.

Referring to FIG. 11, for passive equalization, the equalization module includes: a resistor 811, and each unit cell corresponds to an equalization module, that is, a resistor is connected in parallel with each end of each unit cell.

For a single cell that needs to be passively balanced, the control module controls the parallel loop conduction between the cell that needs to be balanced and its corresponding resistor during the equalization period of the unit period to perform passive equalization of the cell. . Referring to FIG. 11, 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. 11, for active equalization, the equalization module includes a charging branch 94 connected in parallel with each of the unit cells 81 in the battery pack. The charging branch 94 is in one-to-one correspondence with the unit cells 81, 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 balanced 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 11, 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. 11 , the control module can be turned on by controlling the switch 96 corresponding to the single cell that needs to be balanced, so that the charging branch corresponding to the single cell that needs to be balanced is turned on, and the active balancing of the single cells that need to be balanced is performed. .

In other embodiments, for active balancing, in addition to charging a single battery with a generator as shown in FIG. 11, a single battery that needs to be balanced can be charged by a starting battery in the entire vehicle.

In another embodiment, for passive equalization, in addition to the parallel resistor and the unit cell that needs to be balanced, as shown in FIG. 11, the unit cell that needs to be balanced may be connected in parallel with the starting battery of the whole vehicle, which will be required. The power discharged from the balanced single cells 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 disclosure, a plurality of single cells may 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 disclosure, one or more parallel equalization resistors may be provided in a passive equalization circuit of a single cell. Therefore, according to the determined equalization current of the unit cells that need to be equalized, the target number of equalization resistors that need to be connected in parallel with the unit cells that need to be equalized is determined; and the target number of equalization resistors are controlled in parallel with the unit cells that need to be equalized. Or, according to the determined equalization current, determining the resistance value of the equalization resistor that needs to be connected in parallel for the single cell to be equalized; determining the required and balanced cell according to the determined resistance value and the resistance value of each parallelizable equalization resistor Parallel target equalization resistance; and control target equalization resistance in parallel with the unit cell requiring equalization.

Therefore, the control of the equalization current in the passive equalization process can be realized by parallel equalizing the resistance.

In the active equalization circuit of the single cell, one or more equalization resistors connected in series are provided. Therefore, according to the determined equalization current of the unit cells that need to be equalized, the target quantity of the equalization resistance that needs to be connected in series with the unit cells that need to be equalized is determined; and the target number of equalization resistors are controlled in series with the unit cells that need to be equalized. Or, according to the determined equalization current, determining the resistance value of the equalization resistor that needs to be connected in series for the cell to be equalized; determining the required and balanced cell according to the determined resistance value and the resistance value of each series-connected equalization resistor The target equalization resistance in series; and the control target equalization resistance are connected in parallel with the unit cells that need to be equalized.

Therefore, the control of the equalization current in the active equalization process can be realized by the method of series equalizing the resistance.

In an embodiment of the present disclosure, when there are a plurality of cells requiring equalization, one of the cells requiring equalization may be determined as the reference cell. Thereby, the equalization current of the unit cells that need to be equalized can be determined according to the value of the performance parameter of the reference battery, the reference value of the performance parameter and the preset equalization duty ratio. Therefore, by referring to the single cells that need to be equalized, the equalization current of the single cells that need to be equalized can be determined, and the equalization current determination of the single cells that need to be balanced can be eliminated, thereby improving the processing efficiency.

In an embodiment of the present disclosure, when the cells that need to be equalized are equalized according to the preset equalization duty ratio, the cumulative equalization time of the single cells that need to be equalized is reached to the 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. 12, in step S121, the control module controls the control channels of the single cells that need to be equalized, and equalizes the cells that need to be equalized during the equalization period.

In step S122, 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 S124 is performed; if any of the equalization periods of the cells requiring equalization does not meet the requirements, step S123 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 S123, 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 execute step S122.

In step S124, a new round of equalization determination is started, and the battery cells that need to be equalized are determined according to the battery information collected during the collection period, and the equalization current 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 current of each unit cell requiring equalization can 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. 13, in step S131, 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 S132, 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 S133, 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.

Equilibrium current adjustment

In an embodiment of the present disclosure, in the equalization process, when the difference between the value of the performance parameter of the unit cell requiring equalization and the reference value of the performance parameter becomes larger than the difference at the start of the equalization, The equalization current of the cell that needs to be balanced is adjusted to increase, and the reference value is the maximum value, the minimum value, or the average value of the performance parameter of each single cell in the battery group; when a balanced single cell is required The difference between the value of the performance parameter and the reference value of the performance parameter is smaller than the difference at the start of the equalization, and the equalization current of the cell requiring the equalization is adjusted to be reduced.

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

In the embodiment of the present disclosure, the battery information is collected and balanced and time-division, to avoid the influence of the equalization current on the accuracy of the battery information collection when the battery information is collected and equalized; on the other hand, according to the battery information of the single battery, each is determined. The equalization current of the single cells is balanced to improve the equalization efficiency.

Correspondingly, the embodiment of the present disclosure further provides a battery equalization system, including: an equalization module, an acquisition module, and a control module;

In one embodiment, the control module is configured to determine one of the single cells that need to be equalized as a reference battery; and a reference value of the performance parameter of the reference battery according to a value of a performance parameter of the reference battery And determining the equalization current of the single cell that needs to be equalized with the preset equalization duty ratio.

In one embodiment, the performance parameter is a voltage;

The control module is configured to determine, as a reference battery, a single battery that minimizes a difference between a voltage value of the battery pack and a reference value of a voltage, where the reference value of the voltage is a minimum voltage among voltage values of each single battery a value, a maximum voltage value, or an average voltage value; determining a first SOC value corresponding to the reference value of the voltage according to a reference value of the voltage and an OCV-SOC curve of the reference battery; Determining, by the voltage value of the body battery 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; according to the first SOC value, Determining the equalization current of the single cell by describing the second SOC value and the equalization duty ratio.

In one embodiment, the control module is configured to determine a reference OCV value of the reference battery according to a voltage value of the reference battery and an internal resistance value of the reference battery; according to the reference OCV value and the Determining, by the OCV-SOC curve of the battery, a 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.

In one embodiment, the control module is configured to determine a power difference according to ΔQ=ΔSOC×C _n , where ΔQ is the power difference, and ΔSOC is between the first SOC value and the second SOC value SOC difference, C _n is the available capacity of the unit cell to be equalized; determining the equalization current of the unit cell to be equalized according to I=ΔQ/(t×τ), where t is the monomer The preset equalization period of the battery, I is the equalization current, and τ is the equalization duty ratio.

In one embodiment, the performance parameter is a voltage;

The control module is configured to: according to the voltage difference between the voltage value of the single cell that needs to be equalized and the reference value of the voltage, the equalization duty ratio, and the voltage difference value, the equalization duty ratio, and the equalization current The preset relationship between the presets determines the equalization current of the unit cells that need to be balanced.

In one embodiment, the performance parameter is SOC, and the reference value of the SOC is a minimum voltage value, a maximum voltage value, or an average voltage value among SOC values of the respective single cells;

The control module is configured to determine an equalization current of the single cell that needs to be equalized according to the SOC value of the unit cell that needs to be equalized, the reference value of the SOC, and the equalization duty ratio.

In one embodiment, the control module is further configured to determine, according to the equalization current, a target number of equalization resistors that need to be connected in parallel with the unit cells that need to be equalized; and control the target number of equalization resistors and the A balanced single cell is required in parallel.

In one embodiment, the control module is further configured to determine, according to the equalization current, a resistance value of the equalization resistor that needs to be connected in parallel for the single cell that needs to be equalized; and according to the determined resistance value and the equalization resistance of each parallelizable resistor The magnitude of the resistance determines a target equalization resistance that needs to be connected in parallel with the single cell that needs to be balanced; and controls the target equalization resistance to be in parallel with the single cell that needs to be equalized.

In one embodiment, the control module is further configured to: when the equalization process of the single cell that needs to be balanced, detects that any performance parameter of the single cell that needs to be balanced meets the performance When the equalization current adjustment condition corresponding to the parameter is used, the equalization current 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 the rate of change of time.

In one embodiment, 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 that the single battery connected to the control module does not need to be equalized. Controlling the control module to connect with a 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 control module is connected to the acquisition module and the equalization module corresponding to the same single cell through a channel, and the acquisition module and the equalization module time-multiplex the channels.

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 the one 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 an acquisition module and an equalization module corresponding to the same single cell through two pins, the two pins and the two The channels correspond one by one.

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.

Accordingly, embodiments of the present disclosure also provide a vehicle including the battery equalization system described above.

Correspondingly, an embodiment of the present disclosure further provides a computer readable storage medium having stored thereon computer program instructions, which are implemented by a processor to implement the battery equalization method described above.

Correspondingly, an embodiment of the present disclosure 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 disclosure have been described in detail above with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solutions of the present disclosure within the scope of the technical idea of the present disclosure. These simple variations are all within the scope of the disclosure.

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 disclosure will not be further described in various possible combinations.

In addition, any combination of various embodiments of the present disclosure may be made as long as it does not deviate from the idea of the present disclosure, and should also be regarded as the disclosure of the present disclosure.

Claims

A battery equalization method, comprising:

Determining, in the battery pack, the battery cells in the battery pack that need to be equalized according to the battery information of each of the battery cells of the battery unit acquired during the sampling period of the unit period, where the unit period includes the sampling period and the equalization period;

Obtaining, according to battery information of each unit battery, a value of a performance parameter of the unit cell that needs to be equalized and a reference value of the performance parameter, the performance parameter including at least one of the following parameters: voltage, SOC, and Resistance, self-discharge rate, voltage change rate, power change rate, and time change rate;

Determining, according to the value of the performance parameter of the unit cell that needs to be equalized, the reference value of the performance parameter, and the preset equalization duty ratio, the equalization current of the single cell that needs to be equalized, wherein the equalization accounts for The null ratio is a ratio of the duration of the equalization period to the duration of the unit period;

According to the equalization current, the equalization of the cells requiring equalization is controlled during the equalization period of the unit period.
The method of claim 1 further comprising:

Determining one of the cells requiring equalization as a reference battery;

Determining, according to the value of the performance parameter of the unit cell that needs to be equalized, the reference value of the performance parameter, and the preset equalization duty ratio, determining an equalization current of the single cell that needs to be balanced, including:

Determining an equalization current of the unit cells that need to be equalized according to a value of a performance parameter of the reference battery, a reference value of a performance parameter of the reference battery, and the preset equalization duty ratio.
The method of claim 1 wherein said performance parameter is a voltage;

Determining, according to the value of the performance parameter of the unit cell that needs to be equalized, the reference value of the performance parameter, and the preset equalization duty ratio, determining an equalization current of the unit battery that needs to be balanced, including:

The single cell that minimizes the difference between the voltage value of the battery pack and the reference value of the voltage is determined as a reference battery, and the reference value of the voltage is the minimum voltage value, the maximum voltage value or the average of the voltage values of the respective single cells. Voltage value;

Determining, according to a reference value of the voltage and an OCV-SOC curve of the reference battery, a first SOC value corresponding to a reference value of the voltage;

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 an equalization current of the unit cells that need to be equalized according to the first SOC value, the second SOC value, and the equalization duty ratio.
The method according to claim 3, wherein the determining the first SOC value corresponding to the reference value of the voltage according to the reference value of the voltage and the OCV-SOC curve of the reference battery comprises:

Determining a reference OCV value of the reference battery according to a voltage value of the reference battery 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 4, wherein said determining said equalization current of said unit cells to be equalized according to said first SOC value, said second SOC value, and said equalization duty ratio The steps include:

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 the equalization current of the unit cells to be equalized according to I=ΔQ/(t×τ), where t is a preset equalization period of the unit cells to be equalized, I is the equalization current, and τ is the Balanced duty cycle.
The method according to claim 1 or 2, wherein the performance parameter is a voltage;

Determining, according to the value of the performance parameter of the unit cell that needs to be equalized, the reference value of the performance parameter, and the preset equalization duty ratio, determining an equalization current of the unit battery that needs to be balanced, including:

a voltage difference between the voltage value of the unit cell that needs to be equalized and a reference value of the voltage, the equalization duty ratio, and a preset correspondence between the voltage difference value and the equalization duty ratio and the equalization current Relationship, determining the equalization current of the unit cells that need to be balanced.
The method according to claim 1 or 2, wherein the performance parameter is SOC, and the reference value of the SOC is a minimum voltage value, a maximum voltage value or an average voltage value among SOC values of the individual cells;

Determining, according to the value of the performance parameter of the unit cell that needs to be equalized, the reference value of the performance parameter, and the preset equalization duty ratio, determining an equalization current of the unit battery that needs to be balanced, including:

And determining an equalization current of the unit cells that need to be equalized according to the SOC value of the unit cells that need to be equalized, the reference value of the SOC, and the equalization duty ratio.
The method according to any one of claims 1 to 7, wherein the step of determining a unit cell requiring equalization comprises:

Obtaining a voltage value of each unit battery according to battery information of each unit battery;

Determining a reference voltage value according to a voltage value of each of the single cells;

The unit cells that need to be equalized are determined according to the voltage values of the individual cells and the reference voltage value.
The method according to claim 8, wherein the reference voltage value is a minimum voltage value, a maximum voltage value or an average voltage value among voltage values of the individual cells in the battery pack;

The step of determining the cell to be balanced according to the voltage value of each of the cells and the reference voltage value includes:

A single cell having a voltage value of each of the single cells greater than the minimum voltage value is determined as a single cell requiring a balance; or

A single cell having a voltage value of each of the single cells that is less than the maximum voltage value is determined as a single cell that needs to be balanced; or

A single cell in which the voltage value of each of the unit cells is greater than or less than the average voltage value is determined as a single cell requiring a balance.
The method according to any one of claims 1 to 9, wherein the method further comprises:

Determining, according to the equalization current, a target number of equalization resistors that need to be connected in parallel with the unit cells that need to be equalized;

Controlling the target number of equalization resistors in parallel with the unit cells that need to be equalized.
The method according to any one of claims 1 to 10, wherein the method further comprises:

Determining, according to the equalization current, a resistance value of the equalization resistor that needs to be connected in parallel for the single cell that needs to be equalized;

Determining, according to the determined resistance value and the resistance value of each of the parallelizable equalization resistors, a target equalization resistance that needs to be connected in parallel with the single cell that needs to be balanced;

The target equalization resistance is controlled to be in parallel with the unit cell that needs to be equalized.
The method according to any one of claims 1 to 11, 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 current adjustment condition corresponding to the performance parameter, the need balance is required. The equalized current of the single cells 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 claim 12, wherein the adjusting the equalization current of the unit cells that need to be balanced comprises:

When the difference between the value of the performance parameter of the unit cell that needs to be equalized and the reference value of the performance parameter becomes larger than the difference at the start of the equalization, the equalization current of the unit cell that needs to be equalized is performed. An increased adjustment, the reference value being a maximum value, a minimum value, or an average value of values of the performance parameters of each of the unit cells in the battery pack;

When the difference between the value of the performance parameter of the unit cell that needs to be equalized and the reference value of the performance parameter is smaller than the difference at the start of the equalization, the equalization current of the unit cell that needs to be equalized is reduced. Small adjustments.
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 pack during a sampling period of a unit period under the control of the control module;

The control module is configured to determine, according to battery information of each battery cell of the battery unit acquired in a sampling period of a unit period, the unit cells that need to be balanced in the battery group, where the unit period includes the sampling period and the equalization a period of time; obtaining, according to battery information of each unit battery, a value of a performance parameter of the unit cell to be balanced and a reference value of the performance parameter, the performance parameter being any one of the following parameters: voltage, SOC, Internal resistance, self-discharge rate, voltage change rate, power change rate, and time change rate; reference value of the performance parameter and preset equalization duty ratio according to the value of the performance parameter of the unit cell that needs to be equalized Determining an equalization current of the unit cells that need to be equalized, wherein the equalization duty ratio is a ratio of a duration of the equalization period to a duration of the unit period; and according to the equalization current, in the unit period The equalization period controls the equalization of the unit cells that need to be balanced;

The equalization module is configured to equalize the corresponding single cells under the control of the control module.
The system according to claim 14, wherein said control module is configured to determine one of the cells requiring equalization as a reference battery; said reference according to a value of a performance parameter of said reference battery The reference value of the performance parameter of the battery and the preset equalization duty ratio determine the equalization current of the single cell that needs to be equalized.
The system of claim 14 wherein said performance parameter is a voltage;

The control module is configured to determine, as a reference battery, a single battery that minimizes a difference between a voltage value of the battery pack and a reference value of a voltage, where the reference value of the voltage is a minimum voltage among voltage values of each single battery a value, a maximum voltage value, or an average voltage value; determining a first SOC value corresponding to the reference value of the voltage according to a reference value of the voltage and an OCV-SOC curve of the reference battery; Determining, according to the voltage value of the body battery 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; according to the first SOC value, Determining the equalization current of the single cell by describing the second SOC value and the equalization duty ratio.
The system according to claim 16, wherein the control module is configured to determine a reference OCV value of the reference battery according to a voltage value of the reference battery and an internal resistance value of the reference battery; Determining an OCV value and an OCV-SOC curve of the reference battery, determining a 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 17, 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 current of the unit cells that need to be equalized according to I=ΔQ/(t×τ), Where t is the preset equalization time of the single cell, I is the equalization current, and τ is the equalization duty.
A system according to claim 14 or 15, wherein said performance parameter is a voltage;

The control module is configured to: according to the voltage difference between the voltage value of the unit cell that needs to be equalized and the reference value of the voltage, the equalization duty ratio, and the voltage difference value, the equalization duty ratio, and the equalization current The preset relationship between the presets determines the equalization current of the unit cells that need to be balanced.
The system according to claim 14 or 15, wherein the performance parameter is SOC, and the reference value of the SOC is a minimum voltage value, a maximum voltage value or an average voltage value among SOC values of the individual cells;

The control module is configured to determine an equalization current of the single cell that needs to be equalized according to the SOC value of the unit cell that needs to be equalized, the reference value of the SOC, and the equalization duty ratio.
The system according to any one of claims 14 to 20, wherein the control module is further configured to determine, according to the equalization current, a target number of equalization resistors that need to be connected in parallel with the unit cells that need to be balanced. Controlling the target number of equalization resistors in parallel with the single cell requiring equalization.
The system according to any one of claims 14 to 21, wherein the control module is further configured to determine, according to the equalization current, a resistance value of the equalization resistor that needs to be connected in parallel to the unit cells that need to be equalized; Determining, according to the determined resistance value and the resistance value of each of the parallelizable equalization resistors, a target equalization resistance that needs to be connected in parallel with the single cell that needs to be balanced; controlling the target equalization resistance to be connected in parallel with the single cell that needs to be balanced .
The system according to any one of claims 14 to 22, 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 of the performance parameters of the battery meets the equalization current adjustment condition corresponding to the performance parameter, the equalization current of the single cell that needs to be balanced is adjusted, and the performance parameter includes at least: voltage, SOC, internal resistance, Self-discharge rate, voltage change rate, power change rate, and time change rate.
The system according to any one of claims 14 to 23, 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 that is connected to the control module needs to be equalized, the acquiring module and the equalization module time-multiplex the channel; the control module passes through a channel and corresponds to The acquisition module of the same single battery is connected to the equalization module, and the acquisition module and the equalization module time-multiplex the channels.
The system according to claim 24, 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 any one of claims 14 to 23, 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 26, 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 14-27.