CN110015187B

CN110015187B - Battery equalization method, system, vehicle, storage medium and electronic device

Info

Publication number: CN110015187B
Application number: CN201710775046.4A
Authority: CN
Inventors: 罗红斌; 王超; 沈晓峰; 曾求勇; 刘苑红; 张祥
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd
Priority date: 2017-08-31
Filing date: 2017-08-31
Publication date: 2023-01-06
Anticipated expiration: 2037-08-31
Also published as: WO2019042400A1; CN110015187A

Abstract

The present disclosure relates to a battery equalization method, a system, a vehicle, a storage medium, and an electronic device, the method comprising: determining single batteries needing to be balanced in the battery pack according to battery information of each single battery of the battery pack, which is acquired in a sampling time period of a unit cycle; acquiring the value of the performance parameter of the single battery needing to be balanced and the reference value of the performance parameter according to the battery information of each single battery; determining the balancing current of the single battery needing to be balanced according to the value of the performance parameter of the single battery needing to be balanced, the reference value of the performance parameter and a preset balancing duty ratio; and controlling the balance of the single batteries needing to be balanced in the balancing time period of the unit cycle according to the balancing current. According to the method, the battery information acquisition and the equalization are carried out in a time-sharing manner; according to the battery information of the single batteries, the balance current of each single battery is determined for balancing, and the balancing efficiency can be improved.

Description

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, a battery equalization system, a vehicle, a storage medium, and an electronic device.

Background

A large-capacity battery that provides power energy for an electric vehicle is often referred to as a power battery. The vehicle power battery is generally formed by connecting a plurality of single batteries in series to form a module. With the use of batteries, the difference between the single batteries is gradually enlarged, the consistency between the single batteries is poor, and the capacity of the battery pack is limited due to the short plate effect of the batteries, so that the capacity of the battery pack cannot be fully exerted, and the whole capacity of the battery pack is reduced. On the other hand, the gradual expansion of the difference between the single batteries may cause overcharge of some single batteries, over-discharge of some single batteries, affect the service life of the batteries, damage the batteries, and generate a large amount of heat to cause combustion or explosion of the batteries.

Therefore, the method has the advantages of effectively and uniformly managing the power batteries of the electric automobile, being beneficial to improving the consistency of the batteries in the power battery pack, reducing the capacity loss of the batteries, prolonging the service life of the batteries and the driving range of the electric automobile, and having very important significance.

At present, when the battery pack is subjected to equalization management, the magnitude of equalization current can be preset, however, if the set equalization current is too large, the service life of the battery pack may be damaged, and if the set equalization current is too small, the equalization duration may be increased, and the equalization effect is poor. Therefore, how to better determine the equalizing current is a problem to be solved.

Disclosure of Invention

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

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

determining single batteries needing to be balanced in a battery pack according to battery information of each single battery of the battery pack, which is acquired in a sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and a balancing time period;

according to the battery information of each single battery, acquiring the value of the performance parameter of the single battery needing to be balanced and the reference value of the performance parameter, wherein the performance parameter comprises at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate and time change rate;

determining the balancing current of the single battery to be balanced according to the value of the performance parameter of the single battery to be balanced, the reference value of the performance parameter and a preset balancing duty ratio, wherein the balancing duty ratio is the ratio of the duration of the balancing time period to the duration of the unit period;

and controlling the balance of the single batteries needing to be balanced in the balancing time period of the unit cycle according to the balancing current.

In a second aspect, a battery equalization system is provided, comprising: the device comprises a balancing module, an acquisition module and a control module;

the acquisition module is used for acquiring the battery information of each single battery of the battery pack within the sampling time interval of the unit cycle under the control of the control module;

the control module is used for determining the single batteries needing to be balanced in the battery pack according to the battery information of each single battery of the battery pack, which is acquired in the sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and the balancing time period; acquiring a value of a performance parameter of the single battery needing to be balanced and a reference value of the performance parameter according to battery information of each single battery, wherein the performance parameter is any one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate, and time change rate; determining the balancing current of the single battery to be balanced according to the value of the performance parameter of the single battery to be balanced, the reference value of the performance parameter and a preset balancing duty ratio, wherein the balancing duty ratio is the ratio of the duration of the balancing time period to the duration of the unit period; controlling the balancing of the single batteries needing balancing in the balancing time period of the unit cycle according to the balancing current;

and the balancing module is used for balancing the corresponding single batteries under the control of the control module.

In a third aspect, a vehicle is provided, which includes the battery equalization system of the second aspect.

In a fourth aspect, there is provided a computer readable storage medium having computer program instructions stored thereon, wherein the program instructions, when executed by a processor, implement the method of the first aspect.

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

According to the technical scheme, the battery information acquisition and the equalization are carried out in a time-sharing manner, and the battery information acquisition and the equalization are prevented from being carried out simultaneously, so that the acquired battery information is more accurate, and the equalization effect is better; on the other hand, the equalization current is determined according to the value of the performance parameter of the single battery, the reference value of the performance parameter and the preset equalization duty ratio, so that equalization is performed, and the equalization efficiency of the single battery can be improved.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

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

fig. 2 is a schematic diagram of a battery equalization system in which two single batteries share one equalization module according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of a battery equalization system of another embodiment of the present disclosure;

fig. 4 is a schematic diagram of a battery equalization system in which two single batteries 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 flow of determining a single battery requiring equalization according to an embodiment of the present disclosure;

fig. 7 is a schematic flow chart of determining a cell requiring equalization according to voltage in an embodiment of the present disclosure;

fig. 8 is a schematic flowchart illustrating a process of determining an equalization current of a cell requiring equalization according to a voltage value of the cell requiring equalization and a reference voltage value according to an embodiment of the present disclosure;

fig. 9 is an open circuit voltage OCV-remaining capacity SOC curve of a unit cell according to an embodiment of the present disclosure;

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

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

FIG. 12 is a flow diagram of an equalization process according to an embodiment of the present disclosure;

fig. 13 is a flowchart illustrating acquisition of an equalization duration according to an embodiment of the disclosure.

Detailed Description

The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

Referring to fig. 1, a schematic diagram of a battery equalization system according to an embodiment of the present disclosure is shown. This battery equalizing system includes: the system comprises a control module 101, an acquisition module 102, an equalization module 103 and a battery pack 104.

In one embodiment, each 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 battery are respectively connected with the control module 101 through different control channels. The control module can comprise a control chip, the control chip is respectively connected with the acquisition module and the balance module corresponding to the same single battery through two pins, and the two pins correspond to the two channels one by one.

In this embodiment, the control module 101 controls the acquisition module 102 and the equalization module 103 to conduct in a time-sharing manner according to a unit cycle, and respectively performs acquisition of battery information and equalization of a battery, so that the acquisition of the battery information and the equalization are performed in a time-sharing manner. The influence of the equalizing current on the accuracy of battery information acquisition is avoided when the battery information acquisition and the equalization are simultaneously carried out.

In one embodiment, referring to fig. 1, each of the cells is connected to an acquisition module 102 and an equalization module 103, respectively. If the battery pack includes N single batteries, the number of the acquisition modules 102 is N, and the number of the equalization modules 103 is N, so that the control module 101 is connected to each acquisition module and each equalization module through 2 × N control channels.

In other embodiments, different single cells may share an equalization module, for example, N single cells in a battery pack, the same equalization module may be shared, or one equalization module may be shared for each predetermined number (for example, 2, 3, or 5, etc.) of single cells, and the like. When at least two single batteries in the multiple single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected with each single battery in the at least two single batteries needing to be balanced in the balancing time interval of the unit cycle.

Referring to fig. 2, two single batteries share one balancing module, and when two single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected with each single battery in a balancing period of a unit cycle. The alternate connection may be a connection that alternates according to 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 batteries 111 is closed for 2s under the control of the control module 14, the parallel switch 150 on the parallel branch 15 corresponding to the other of the two single batteries 111 is opened for 2s 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 batteries 111 is switched from the closed state to the open state or from the open state to the closed state every two seconds in the equalization period. Therefore, on the basis of time-sharing conduction of the acquisition module and the equalization module, the single batteries sharing the same equalization module are alternately connected with the shared equalization module during the equalization time period, and equalization is realized.

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

This battery equalizing system includes: a control module 301, an acquisition module 302, an equalization module 303, and a battery pack 304. 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 battery through a control channel 305, and the acquisition module 302 and the equalization module 303 multiplex the control channel 305 in time division according to a unit cycle. The control module 301 is configured to control the control module to connect with the corresponding sampling module when it is determined that the single battery connected with the control module does not need to be balanced; or, the control module is further configured to multiplex the channels 305 in time division according to a unit period by the acquisition module and the equalization module when it is determined that the single battery connected to the control module needs equalization.

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 in an acquisition time period to obtain the battery information of the single battery. The battery information includes at least one of: voltage, current, temperature, etc. In one embodiment, the battery information may include only the voltage value, and thus, the voltage performance parameter of the unit battery may be obtained. In another embodiment, the battery information may also include a voltage value, a current value, a temperature value, and the like, so as to obtain performance parameters such as SOC, internal resistance, self-discharge rate, and the like of the single battery. The control module 301 determines the single battery needing to be balanced according to the battery information of the single battery acquired by the acquisition module 302. For the single battery needing to be balanced and started, the control module 301 controls the balancing module corresponding to the single battery needing to be balanced, and balances the single battery needing to be balanced in a balancing time period.

Therefore, in the embodiment of the disclosure, the acquisition module and the balancing module share the same control channel, the control module controls the acquisition module and the balancing module, and the control channel is multiplexed in time according to a unit period, so that the influence of balancing current on the accuracy of battery information acquisition is avoided when the battery information acquisition and the balancing are performed simultaneously; on the other hand, compared with the embodiment shown in fig. 1, the requirement for 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 disposed in a control channel shared by the acquisition module and the equalization module, and the control module 301 is connected to the switch K and is connected to the acquisition module 302 or the equalization module 303 in a time-sharing manner by controlling the switch K. When the switch K is connected with the acquisition module 302, the control module 301 controls the acquisition module 302 to acquire battery information of the single battery in an acquisition period; when the switch K is connected to the balancing module 303, the control module 301 controls the balancing module 303 to balance the corresponding single battery.

From this, through with switch setting between control module and collection module, balanced module, control module can reach the effect of collection and equilibrium through regulating switch's state to not sampling when can realizing the equilibrium, unbalanced effect during the sampling, thereby balanced electric current can not influence battery voltage, thereby precision when having improved battery voltage sampling.

In one embodiment, referring to fig. 1, each cell of the battery is connected to an acquisition module 302 and an equalization module 303, respectively. If the battery pack includes N single batteries, the number of the acquisition modules 302 is N, and the number of the equalization modules 303 is N, so that the control module 301 is connected to the acquisition modules and the equalization modules through N control channels.

In the embodiment of the 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, and the requirement on the number of channels of a control module chip is further reduced.

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, 2N control channels correspond to N single batteries. In the embodiment, the acquisition module and the equalization module of the same single battery share one control channel to be connected with the control module, and the N single batteries correspond to the N control channels, so that the number of the control channels can be reduced, and the cost of the control module is reduced.

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 unit cells correspond to the 2N control channels, and the 2N control channels need to be controlled. According to the battery pack control system, the acquisition module and the balance module of the same single battery share one control channel of the control module, so that N single batteries correspond to N control channels, and only the N control channels are required to be controlled, so that the control flow can be simplified, and the misoperation rate of the control module is reduced.

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 unit cells correspond to the 2N control channels, and the qualification rate of the control module connected through the control channels is determined by the qualification rate of the 2N control channels. In this embodiment, the acquisition module and the equalization module of the same single battery share one control channel of the control module, the N single batteries correspond to the N control channels, and the qualification rate of the control module connected through the control channels is determined by the qualification rate of the N control channels, so that the total qualification rate of the plurality of single batteries connected through the control channels to the control module in the whole system can be improved, and the qualification rate of the battery equalization system is further improved.

In other embodiments, different cells may share an equalization module, for example, N cells in a battery pack, the same equalization module may be shared, or one equalization module may be shared for each predetermined number (e.g., 2, 3, or 5, etc.) of cells, and so on. When at least two single batteries in the multiple single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected with each single battery in the at least two single batteries needing to be balanced in the balancing time interval of the unit cycle.

In an embodiment of the present disclosure, a battery equalization system includes: a Battery Management Controller (BMC) and a plurality of Battery Information Collectors (BIC). In one embodiment, the control module 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 acquisition module sends acquired parameter information of the single batteries in the battery pack to the second control unit through the first control unit; the acquisition module and the balance module of the same single battery correspond to one connecting channel of the first control unit.

The first control unit can be connected to the acquisition module by controlling the connecting channel, and then the acquisition module is controlled to acquire parameter information of the single batteries in the battery pack. The second control unit can also send a collection instruction to the first control unit through the communication unit so as to control the connection channel to be connected to the collection module through the first control unit.

The first control unit can be connected to the balancing module by controlling the connecting channel, so as to control the balancing module to perform balancing processing on the single batteries needing to be balanced. The first control unit can send the parameter information of the battery pack acquired by the acquisition circuit to the second control unit, the second control unit determines the single battery needing to be balanced according to the parameter information of the battery pack, and sends a balancing instruction to the first control unit through the communication unit so as to control the connection channel to be connected to the balancing module through the first control unit.

When the acquisition module in the battery equalization system sends acquired parameter information of the single batteries in the 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 one connection channel of the first control unit, and the number of channels required by the first control unit is reduced.

The first control unit of the battery information collector and the second control unit of the battery management controller can selectively perform balance control on the single batteries needing to be balanced. Namely, the first control unit may control the balancing module to perform balancing processing on the single battery to be balanced, and the second control unit may also control the balancing module to perform balancing processing on the single battery to be balanced. The first control unit or the second control unit determines the single batteries needing to be balanced according to the parameter information of the battery pack acquired by the acquisition module.

When the battery information collector does not receive the balancing instruction sent by the battery management controller within the preset time, the first control unit receives the parameter information of the battery pack and controls the balancing module to balance the single batteries needing to be started when determining that the single batteries in the battery pack need to be started according to the parameter information of the battery pack.

When the battery information collector receives an instruction for indicating the battery information collector to perform equalization processing, the first control unit receives parameter information of the battery pack and controls the equalization module to perform equalization processing on the single batteries needing to be started when determining that the single batteries in the battery pack need to be started for equalization according to the parameter information of the battery pack.

When the battery information collector receives a fault message of the battery management controller, the first control unit receives parameter information of the battery pack and controls the balancing module to balance the single batteries needing to be started and balanced when the single batteries in the battery pack need to be started and balanced according to the parameter information of the battery pack.

The battery information collector and the battery management controller can selectively control the balancing system through the first control unit and the second control unit, so that the normal operation of the battery balancing system can still be ensured under the condition that one of the battery information collector and the battery management controller fails or fails.

Referring to fig. 4, an exemplary schematic diagram of two unit cells sharing one balancing module is shown. When two single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected with each single battery in the balancing time interval of the unit cycle. The alternate connection may be a connection that alternates according to a certain period. Therefore, on the basis of time-sharing conduction of the acquisition module and the equalization module, the single batteries sharing the same equalization module are alternately connected with the shared equalization module during the equalization time period, and equalization is realized.

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

In the embodiment of the disclosure, the unit cycle is divided into the acquisition time period and the equalization time period, and the ratio of the duration of the equalization time period to the duration of the unit cycle is the equalization duty ratio. According to the battery balancing method, after the balancing duty ratio of the single battery needing to be balanced is determined, the balancing of the single battery needing to be balanced is controlled according to the determined balancing duty ratio, so that the balancing efficiency is improved, and the balancing cost is saved.

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

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

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

In step S53, the balancing current of the single battery to be balanced is determined according to the value of the performance parameter of the single battery to be balanced, the reference value of the performance parameter and the preset balancing duty ratio.

In step S54, the equalization of the unit cells requiring equalization is controlled in the equalization period of the unit cycle according to the equalization current.

Therefore, in the embodiment of the disclosure, the battery information acquisition and the equalization are carried out in a time-sharing manner, so that the influence of the equalization current on the accuracy of the battery information acquisition is avoided when the battery information acquisition and the equalization are carried out simultaneously; on the other hand, the balance current of each single battery is determined according to the battery information of the single batteries so as to carry out balancing, so that different balance currents can be adopted for different single batteries, and the balancing efficiency of the single batteries is improved.

In an embodiment of the present disclosure, the single battery needing equalization is determined from the battery pack according to the performance parameters of each single battery in the battery pack. Wherein the performance parameters include at least one of: at least one of a voltage, a SOC, an internal resistance, a self-discharge rate, a rate of change of voltage, a rate of change of charge, and a rate of change of time.

Referring to fig. 6, in an embodiment of the present disclosure, the cell requiring equalization is determined by:

in step S61, a difference between the performance parameter of the at least one cell and a reference value of the performance parameter is determined.

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

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

As described above, when the performance parameter is voltage, the above-described step of determining the unit cells requiring equalization is described with reference to fig. 7:

in step S71, a voltage difference between the voltage value of at least one of the unit cells and the reference voltage value is determined.

In step S72, a cell, of the at least one cell, in which a voltage difference between the voltage value and the reference voltage value is greater than or equal to the equalization start threshold value is determined as a cell requiring equalization.

When the reference voltage value is the minimum value among the voltage values of the respective unit cells, step S71 includes:

comparing the voltage value of the single battery with the maximum voltage value in the battery pack with a reference voltage value; or comparing the voltage values of the other single batteries except the single battery with the minimum voltage value in the battery pack with the reference voltage value.

When the reference voltage value is the minimum value of the voltage values of the single batteries, the subsequent balancing treatment on the determined single batteries needing balancing is as follows: and controlling the discharge of the single battery needing to be balanced and executing passive balance.

When the reference voltage value is the maximum value among the voltage values of the respective unit cells, step S71 includes:

comparing the voltage value of the single battery with the minimum voltage value in the battery pack with a reference voltage value; or comparing the voltage values of the other single batteries except the single battery with the maximum voltage value in the battery pack with the reference voltage value.

When the reference voltage value is the maximum value of the voltage values of the single batteries, the subsequent balancing treatment on the determined single batteries needing balancing is as follows: and controlling the charging of the single battery needing to be balanced, and executing active balancing.

When the reference voltage value is an average value of the voltage values of the respective unit cells, step S71 includes:

and comparing the voltage value of each single battery in the battery pack with a reference voltage value respectively.

When the reference voltage value is the average value of the voltage values of the single batteries, the subsequent balancing treatment on the determined single batteries needing balancing is as follows: controlling the single battery with the voltage value smaller than the reference voltage value to charge, and executing active equalization; and controlling the discharge of the single batteries with the voltage values larger than the reference voltage value, and executing passive equalization.

It should be understood that, referring to table 1 below, the correspondence table of the equalization judgment and equalization manner when the performance parameter is SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate, or time change rate, respectively.

The self-discharge rate of the single battery is used for representing the capacity loss condition and the capacity loss rate of the single battery. In one embodiment, when the battery pack stops working and reaches a stable state (at the time t 1), detecting and recording an open-circuit voltage value V1 of each single battery of the power battery pack; when the battery pack starts to work again (at the moment of t 2), detecting and recording the open-circuit voltage value V2 of each single battery of the power battery pack; and calculating the self-discharge rate eta of each single battery according to the open-circuit voltage value of each single battery obtained by the two detections. The open circuit voltage value can be calculated by the following equation (1).

The voltage change rate of the unit cells may be a voltage change rate of the unit cells during charging (or discharging), i.e., the voltage change rate of the unit cells may be a voltage change amount at which a unit change of a specified physical quantity of the unit cells occurs. For example, in the present disclosure, to charge or discharge a preset amount of electricity to the unit cell, a voltage variation dv/dq of the unit cell; or, a preset time period for charging or discharging the single battery and a voltage variation dv/dt of the single battery are described as an example.

The rate of change in the amount of charge of the unit cells may be an amount of change in voltage at which a unit of change in a specified physical quantity of the unit cells occurs. For example, the present disclosure will be described by taking as an example the amount of power required to be charged by increasing the voltage of the unit cell by one unit voltage from the initial voltage, or the amount of power reduced by decreasing the voltage of the unit cell by one unit voltage from the initial voltage.

The time change rate of the unit cells may be a time period required for a unit change of a specified physical quantity of the unit cells. For example, the present disclosure will be described taking as an example a charging time required for the voltage of the unit cell to rise by one unit voltage from the initial voltage, or a discharging time required for the voltage of the unit cell to fall by one unit voltage from the initial voltage.

TABLE 1

Therefore, when the equalization judgment is carried out by adopting the performance parameters of different batteries, the judgment is carried out according to the corresponding mode in the table 1, and the single batteries needing equalization in the battery pack are determined by combining the judgment flow when the performance parameters are voltages.

It should be understood that if it is determined in step S51 that there is no cell that needs to be equalized, the equalization determination continues based on the information collected in the next collection period. When the single batteries needing to be balanced are determined to be absent according to the information acquired in the acquisition time period, the control module does not act in the balancing time period, so that the balancing module corresponding to any battery is not started.

In an embodiment of the present disclosure, determining an equalization current of the single battery needing equalization according to the value of the performance parameter of the single battery needing equalization, the reference value of the performance parameter, and a preset equalization duty cycle, includes:

and determining the balancing current of the single battery to be balanced according to the difference between the performance parameter value of the single battery to be balanced and the reference value of the performance parameter, the preset balancing duty ratio and the corresponding relationship between the preset difference and the balancing duty ratio and the balancing current. For example, when the performance parameter is voltage, the balancing current of the single battery needing balancing is determined according to a voltage difference value between a voltage value of the single battery needing balancing and a reference value of the voltage, a preset balancing duty ratio and a corresponding relationship between the preset voltage difference value and the balancing duty ratio and the balancing current.

Referring to fig. 8, in the equalizing 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 cell in the battery pack having the smallest difference between the voltage value and the reference value of the voltage is determined as the reference cell. The reference value of the voltage is the minimum voltage value, the maximum voltage value or the average voltage value in the voltage values of the single batteries;

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 an open-circuit voltage OCV-remaining capacity SOC curve of the reference battery.

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

In step S84, the balancing current of the single battery is determined according to the first SOC value, the second SOC value and the balancing duty ratio.

Referring to fig. 9, a graph of an open circuit voltage OCV versus a remaining capacity SOC of a unit cell according to an embodiment of the present disclosure is shown.

The step S82 includes:

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

The step S93 includes:

determining the OCV value of the single battery needing to be balanced according to the voltage value of the single battery needing to be balanced and the internal resistance value of the single battery needing to be balanced; and then, determining the SOC value corresponding to the OCV value of the single battery needing to be balanced as a second SOC value according to the OCV-SOC curve of the single battery needing to be balanced.

Hereinafter, a process of obtaining the SOC value by the voltage value and the internal resistance value will be described with reference to fig. 10 and equation (1):

referring to fig. 10 and equation (1), when the battery pack is in a discharge state or a charge state, the cell is equivalent to an ideal voltage source and is connected in series with a resistor R by using a cell internal resistance model. Then, for a single battery, the sampled voltage value V of the single battery can be obtained according to the formula (1) _L (i.e., load voltage value) to open circuit voltage value:

OCV＝V _L +I×R (1)

wherein, V _L The load voltage value collected by the collecting module in the collecting time period; i is the discharging current or the charging current collected by the collecting module in the collecting time period; and R is the internal resistance value of the single battery.

The internal resistance value of the unit cell may be preset. Or the internal resistance value of the unit cell may be determined according to 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 of the voltage, the capacity, and the internal resistance value of the unit cell. It should be understood that other battery models may also be employed, such as: the Thevenin model, the PNGV (partnership for a new generation of vehicles) model and the like realize the conversion of the collected load voltage of the single battery into the open-circuit voltage.

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

It should be understood that the OCV-SOC curve shown in fig. 9 may 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 may be obtained through measurement. For example, in the process of changing the SOC value of a certain unit cell from 0 to 100%, the open circuit voltage OCV of the primary cell is measured at certain SOC intervals, and then the OCV and the SOC corresponding to each point are in one-to-one correspondence to form an SOC-OCV curve or an OCV-SOC correspondence table of the unit cell.

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

Therefore, 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. And acquiring a second SOC value of the single battery needing to be balanced according to the voltage value of the single battery needing to be balanced, the internal resistance value of the single battery needing to be balanced and the OCV-SOC curve corresponding to the single battery needing to be balanced.

Next, the difference in electric quantity is determined according to equation (2):

ΔQ＝ΔSOC×C _n (2)

where Δ Q is the difference in electrical quantities, Δ SOC is the difference in SOC between the first and second SOC values, C _n The available capacity of the single battery needing to be balanced.

Determining the equalizing current of the single battery needing to be equalized according to the formula (3):

I＝ΔQ/(t×τ) (3)

wherein t is a preset equalization duration of the single battery needing equalization, I is an equalization current of the single battery needing equalization, and τ is an equalization duty ratio. The preset equalization current can be determined according to the resistance value of the resistor of the equalization module, the current provided by the generator and the like, or can be set according to the actual equalization requirement.

Equalization process

Fig. 11 is a schematic diagram of an equalizing module according to an embodiment of the disclosure. And controlling the single batteries needing to be balanced in the balancing time period of the unit cycle, wherein the balancing needs to be carried out in combination with the balancing judgment. In the step of judging the equalization, it is determined whether the equalization mode of the single battery needing equalization is passive equalization (i.e. discharging the single battery needing equalization) or active equalization (i.e. charging the single battery needing equalization), and the corresponding equalization module is turned on.

Referring to fig. 11, for passive equalization, the equalization module includes: and each single battery corresponds to one equalizing module, namely two ends of each single battery are connected with one resistor in parallel.

For the single battery needing to be passively balanced and needing to be balanced, in the balancing time period of a unit cycle, the control module controls the conduction of a parallel loop between the single battery needing to be balanced and the corresponding resistor of the single battery, so that the passive balancing of the single battery is executed. Referring to fig. 11, the control module controls the switch module 812 to be turned on, so as to achieve the conduction of the parallel loop between the single battery needing to be balanced and the corresponding resistor.

The resistor 811 may be a fixed resistor or a variable resistor. In one embodiment, the resistor 811 may be a positive temperature coefficient thermistor, which may change with the temperature change, so as to adjust the balancing current generated during balancing, thereby automatically adjusting the heat generation amount of the battery balancing system, and finally effectively controlling the temperature of the battery balancing system.

Referring to fig. 11, for active equalization, the equalization module includes a charging branch 94 connected in parallel with each battery cell 95 in the battery pack, the charging branches 94 correspond to the battery cells 95 one by one, and each charging branch 94 is connected to the generator 92, and the generator 92 is mechanically connected to the engine 91 through a gear.

For the single battery needing equalization and needing active equalization, the control module controls the charging branch 94 corresponding to the single battery needing equalization to be conducted. When the engine 91 rotates, the generator 92 is driven to generate electricity, so that the electricity generated by the generator 92 is transmitted to the single battery needing to be balanced, and the electricity of the single battery needing to be balanced is increased.

Referring to fig. 11, when the generator 92 is an alternator, the balancing module further comprises a rectifier 93 in series with the generator 92, each charging branch 94 being in series with the rectifier 93. After the alternating current generated by the generator 92 is converted into direct current by the rectifier 93, the generator 92 can be used for charging the single batteries needing to be balanced.

Referring to fig. 11, the control module may control the switch 96 corresponding to the single battery needing to be equalized to be turned on, so that the charging branch corresponding to the single battery needing to be equalized is turned on, and active equalization of the single battery needing to be equalized is performed.

In other embodiments, in addition to charging the single batteries by the generator as shown in fig. 11, the single batteries to be equalized may also be charged by the starting battery in the entire vehicle.

In another embodiment, in addition to the parallel resistor and the single battery needing to be balanced shown in fig. 11, the single battery needing to be balanced may be connected in parallel with the starting battery of the entire vehicle, and the electric quantity discharged by the single battery needing to be balanced is charged into the starting battery, so that the single battery needing to be balanced is balanced, and energy waste is effectively avoided.

As described above, in the embodiment of the present disclosure, a plurality of single batteries may share one balancing module, and when at least two single batteries among a plurality of single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected to each single battery among the at least two single batteries needing to be balanced in a balancing period of a unit cycle, and balancing is performed separately.

In the embodiment of the disclosure, one or more balancing resistors connected in parallel can be arranged in the passive balancing circuit of the single battery. Therefore, according to the determined balancing current of the single battery needing to be balanced, the target number of balancing resistors needing to be connected with the single battery needing to be balanced in parallel is determined; and controlling a target number of balancing resistors to be connected in parallel with the single batteries needing balancing. Or determining the resistance value of the balancing resistor which needs to be connected in parallel for the single battery needing to be balanced according to the determined balancing current; determining a target balancing resistor which needs to be connected with the single battery needing balancing in parallel according to the determined resistance value and the resistance value of each balancing resistor which can be connected in parallel; and controlling the target balancing resistance to be connected with the single batteries needing balancing in parallel.

Therefore, the control of the balance current in the passive balance process can be realized in a mode of connecting balance resistors in parallel.

In the active equalization circuit of the single battery, one or more equalization resistors connected in series are provided. Therefore, according to the determined balancing current of the single battery needing to be balanced, the target number of balancing resistors which are required to be connected with the single battery needing to be balanced in series is determined; and controlling a target number of balancing resistors to be connected in series with the single batteries needing balancing. Or determining the resistance value of the balancing resistor which needs to be connected in series with the single battery needing to be balanced according to the determined balancing current; determining a target balancing resistor which needs to be connected with the single battery needing balancing in series according to the determined resistance value and the resistance value of each balancing resistor which can be connected in series; and controlling the target balancing resistance to be connected with the single batteries needing balancing in parallel.

Therefore, the balance current can be controlled in the active balance process by connecting balance resistors in series.

In an embodiment of the present disclosure, when there are a plurality of unit cells that need to be equalized, one of the unit cells that need to be equalized may be determined as a reference cell to be equalized. Therefore, the balancing current of the single battery needing balancing can be determined according to the value of the performance parameter of the battery to be balanced, the reference value and the preset balancing duty ratio. Therefore, the balancing current of the single battery needing to be balanced is determined by referring to the single battery needing to be balanced, the balancing current can be determined for the single batteries needing to be balanced one by one, and the processing efficiency is improved.

In an embodiment of the present disclosure, when balancing the single battery needing balancing according to a preset balancing duty ratio, the accumulated balancing time of the single battery needing balancing needs to reach the preset balancing time. Due to the limited duration of a single unit cycle, equalization of a cell requiring equalization may be performed during one or more equalization periods of the unit cycle.

Referring to fig. 12, in step S121, the control module controls the control channels of the cells requiring equalization, and equalizes the cells requiring equalization in an equalization period.

In step S122, when a single balancing time period ends, the control module determines whether the balancing of all the single batteries needing to be balanced is completed, that is, whether the accumulated balancing time length of all the single batteries needing to be balanced reaches the corresponding preset balancing time length. If the equalization duration of all the single batteries needing equalization reaches the requirement, executing step S124; if the equalization duration of any single battery needing equalization does not meet the requirement, step S123 is executed.

When the single batteries needing to be balanced are balanced in a balancing time period, when the accumulated balancing time of any single battery needing to be balanced reaches the corresponding preset balancing time, the balancing of the single battery needing to be balanced is controlled to stop.

In step S123, when a single unit cycle is ended, if the accumulated equalization duration of any single battery that needs equalization does not reach the preset equalization duration corresponding to the accumulated equalization duration, after the sampling duration of the next unit cycle is ended, in the equalization duration, the equalization of the single battery that does not reach the equalization duration is continuously controlled, and step S122 is executed.

In step S124, a new round of equalization judgment is started, and according to the battery information acquired in the acquisition time period, the single batteries needing equalization are judged and the equalization current of each single battery needing equalization is determined.

It should be understood that, in a new round of equalization judgment, the determination of the single batteries needing equalization and the determination of the equalization current of each single battery needing equalization can be performed in the manner described above.

The preset equalization duration of the single battery needing equalization in the above embodiment may be preset to be a fixed value according to an actual equalization requirement, for example, the equalization duration may be preset to be a fixed value according to an expansion change condition of the difference of the single battery over time, a requirement of an equalization function capability of the system, and the like. In addition, the preset equalization time length required by the current equalization can be determined according to the historical equalization condition of the single battery needing equalization in the following mode.

Referring to fig. 13, in step S131, target parameter information of the battery to be equalized is acquired. The target parameter comprises any one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, rate of change of voltage, rate of change of electrical quantity, and rate of change of time.

In step S132, the historical balancing duration and the historical parameter information of the single battery needing balancing are obtained, where the historical parameter information is the historical information of the target parameter information.

In step S133, the balancing duration required for balancing the single battery requiring balancing at this time is determined according to the target parameter information, the historical balancing duration and the historical parameter information. The equalization duration is used as the preset equalization duration.

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

wherein, t _k The equalization duration is the equalization time; t is t _k-1 The historical balancing time of the last balancing of the single battery needing balancing is prolonged; delta S _k The difference value between the target parameter of the single battery to be balanced and the reference value of the target parameter is the current moment; delta S _k-1 Target parameters of the single batteries needing to be balanced and reference values of the target parameters at the last balancing momentThe difference between them; c _k The current available capacity of the single batteries needing to be balanced at the current moment; c _k-1 And the historical available capacity of the single batteries needing to be balanced at the last balancing moment.

Adjustment of equalizing current

In an embodiment of the disclosure, in an equalization process, when a difference between a value of a performance parameter of a single battery to be equalized and a reference value of the performance parameter is larger than a difference at the beginning of equalization, performing increased adjustment on an equalization current of the single battery to be equalized, where the reference value is a maximum value, a minimum value, or an average value of values of the performance parameter of each single battery in the battery pack;

when the difference between the value of the performance parameter of the single battery needing to be balanced and the reference value of the performance parameter is smaller than the difference at the beginning of the balancing, the balancing current of the single battery needing to be balanced is subjected to reduced adjustment.

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

In the embodiment of the disclosure, the battery information acquisition and the equalization are carried out in a time-sharing manner, so that the influence of the equalization current on the accuracy of the battery information acquisition is avoided when the battery information acquisition and the equalization are carried out simultaneously; on the other hand, the equalization current of each single battery is determined according to the battery information of the single batteries so as to perform equalization, and therefore equalization efficiency can be improved.

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

In one embodiment, the control module is used for determining one of the single batteries needing to be equalized as a reference battery to be equalized; and determining the balancing current of the single battery needing balancing according to the value of the performance parameter of the reference battery to be balanced, the reference value and the preset balancing duty ratio.

In one embodiment, the performance parameter is voltage;

the control module is used for determining the single battery with the minimum difference between the voltage value in the battery pack and the reference value of the voltage as a reference battery, wherein the reference value of the voltage is the minimum voltage value, the maximum voltage value or the average voltage value in the voltage values of the single batteries; determining a first SOC value corresponding to the reference value of the voltage according to the reference value of the voltage and an OCV-SOC curve of the reference battery; determining a second SOC value corresponding to the voltage value of the single battery needing to be balanced according to the voltage value of the single battery needing to be balanced and the OCV-SOC curve corresponding to the single battery needing to be balanced; and determining the balance current of the single battery according to the first SOC value, the second SOC value and the balance duty ratio.

In one embodiment, the control module is used for determining a reference OCV value of the reference battery according to the voltage value of the reference battery and the internal resistance value of the reference battery; determining an SOC value corresponding to the reference OCV value as the first SOC value according to the reference OCV value and an OCV-SOC curve of the reference battery; and

determining the OCV value of the single battery needing to be balanced according to the voltage value of the single battery needing to be balanced and the internal resistance value of the single battery needing to be balanced; and determining the SOC value corresponding to the OCV value of the single battery needing to be balanced as the second SOC value according to the OCV-SOC curve of the single battery needing to be balanced.

In one embodiment, the control module is configured to control the power converter according to Δ Q = Δ SOC × C _n Determining a difference in electrical quantities, where Δ Q is the difference in electrical quantities, Δ SOC is a difference in SOC between the first and second SOC values, and C _n The available capacity of the single battery needing to be balanced is obtained; and determining the balancing current of the single battery needing balancing according to I = delta Q/(t multiplied by tau), wherein t is preset balancing duration of the single battery, I is the balancing current, and tau is the balancing duty ratio.

In one embodiment, the performance parameter is voltage;

the control module is used for determining the balancing current of the single battery needing balancing according to the voltage difference value between the voltage value of the single battery needing balancing and the reference value of the voltage, the balancing duty ratio, the preset voltage difference value and the corresponding relation between the balancing duty ratio and the balancing current.

In one embodiment, the performance parameter is SOC, and the reference value of SOC is a minimum voltage value, a maximum voltage value or an average voltage value among SOC values of each unit cell;

the control module is used for determining the balancing current of the single battery needing balancing according to the SOC value of the single battery needing balancing, the reference value of the SOC and the balancing duty ratio.

In one embodiment, the control module is further configured to determine, according to the balancing current, a target number of balancing resistors that need to be connected in parallel with the single battery cell that needs to be balanced; and controlling the target number of balancing resistors to be connected in parallel with the single batteries needing balancing.

In one embodiment, the control module is further configured to determine, according to the balancing current, a resistance value of a balancing resistor that needs to be connected in parallel to the single battery that needs to be balanced; determining a target balancing resistor which needs to be connected with the single battery needing balancing in parallel according to the determined resistance value and the resistance value of each balancing resistor which can be connected in parallel; and controlling the target balancing resistance to be connected with the single battery needing balancing in parallel.

In one embodiment, the control module is further configured to, in a balancing process of the single battery cells requiring balancing, adjust a balancing current of the single battery cells requiring balancing when it is detected that any one of performance parameters of the single battery cells requiring balancing satisfies a balancing current adjustment condition corresponding to the performance parameter, where the performance parameters at least include: voltage, SOC, internal resistance, self-discharge rate, rate of change of voltage, rate of change of electrical quantity, and rate of change of time.

In one embodiment, the control module is connected with the acquisition module and the equalization module corresponding to the same single battery through a channel, and the control module is used for controlling the control module to be connected with the corresponding sampling module when the single battery connected with the control module is determined not to need equalization; alternatively, the first and second electrodes may be,

the control module is further used for multiplexing the channels in a time-sharing manner by the acquisition module and the balancing module when the single battery connected with the control module needs to be balanced. The control module is connected with the acquisition module and the balance module corresponding to the same single battery through a channel, and the acquisition module and the balance module multiplex the channel in a time-sharing manner.

In one embodiment, the control module comprises a control chip, and the control chip is connected with the acquisition module and the equalization module corresponding to the same single battery through one pin and one channel.

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

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

With regard to the system in the above embodiment, the specific manner in which each module performs the operation has been described in detail in the embodiment related to the method, and will not be elaborated here.

Correspondingly, the embodiment of the disclosure also provides a vehicle, which comprises the battery equalization system.

Accordingly, the disclosed embodiments also provide a computer readable storage medium, on which computer program instructions are stored, and the program instructions, when executed by a processor, implement the above battery equalization method.

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

The preferred embodiments of the present disclosure are described in detail 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 may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, various possible combinations will not be separately described in this disclosure.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. A method of balancing a battery, comprising:

acquiring a value of a performance parameter of the single battery needing to be balanced and a reference value of the performance parameter according to battery information of each single battery, wherein the performance parameter comprises at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate and time change rate;

controlling the balancing of the single batteries needing balancing in the balancing time period of the unit cycle according to the balancing current;

wherein the step of determining the single batteries needing to be balanced in the battery pack comprises the following steps:

determining a difference between a value of a performance parameter of at least one cell and a reference value of the performance parameter;

and determining the single battery needing to be balanced, wherein the difference between the value of the performance parameter and the reference value of the performance parameter in at least one single battery is larger than or equal to a balancing starting threshold value.

2. The method of claim 1, further comprising:

determining one of the single batteries needing to be balanced as a reference battery to be balanced;

the determining the balancing current of the single battery needing to be balanced according to the value of the performance parameter of the single battery needing to be balanced, the reference value of the performance parameter and a preset balancing duty ratio comprises the following steps:

and determining the balancing current of the single battery needing balancing according to the value of the performance parameter of the reference battery to be balanced, the reference value and the preset balancing duty ratio.

3. The method of claim 1, wherein the performance parameter is voltage;

determining the single battery with the minimum difference between the voltage value in the battery pack and the reference value of the voltage as a reference battery, wherein the reference value of the voltage is the minimum voltage value, the maximum voltage value or the average voltage value in the voltage values of the single batteries;

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

determining a second SOC value corresponding to the voltage value of the single battery needing to be balanced according to the voltage value of the single battery needing to be balanced and the OCV-SOC curve corresponding to the single battery needing to be balanced;

and determining the balance current of the single battery according to the first SOC value, the second SOC value and the balance duty ratio.

4. The method according to claim 3, wherein said determining a first SOC value corresponding to a reference value of said voltage from said reference value of said voltage and an OCV-SOC curve of said reference battery comprises:

determining a reference OCV value of the reference battery according to the voltage value of the reference battery and the internal resistance value of the reference battery;

determining an SOC value corresponding to the reference OCV value as the first SOC value according to the reference OCV value and an OCV-SOC curve of the reference battery;

the determining a second SOC value corresponding to the voltage value of the single battery to be balanced according to the voltage value of the single battery to be balanced and the OCV-SOC curve corresponding to the single battery to be balanced includes:

determining the OCV value of the single battery needing to be balanced according to the voltage value of the single battery needing to be balanced and the internal resistance value of the single battery needing to be balanced;

and determining the SOC value corresponding to the OCV value of the single battery needing to be balanced as the second SOC value according to the OCV-SOC curve of the single battery needing to be balanced.

5. The method according to claim 4, wherein the step of determining the balancing current of the single battery needing balancing according to the first SOC value, the second SOC value and the balancing duty ratio comprises:

as Δ Q = Δ SOC × C _n Determining a difference in electrical quantities, where Δ Q is the difference in electrical quantities, Δ SOC is a difference in SOC between the first and second SOC values, and C _n The available capacity of the single battery needing to be balanced is obtained;

and determining the balancing current of the single battery needing balancing according to I = delta Q/(t multiplied by tau), wherein t is a preset balancing time length of the single battery needing balancing, I is the balancing current, and tau is the balancing duty ratio.

6. The method of claim 1, wherein the performance parameter is voltage;

and determining the balancing current of the single battery needing to be balanced according to the voltage difference value between the voltage value of the single battery needing to be balanced and the reference value of the voltage, the balancing duty ratio, the preset voltage difference value and the corresponding relationship between the balancing duty ratio and the balancing current.

7. The method according to claim 1, wherein the performance parameter is SOC, and the reference value of SOC is a minimum voltage value, a maximum voltage value, or an average voltage value among SOC values of the respective unit cells;

and determining the balancing current of the single battery needing to be balanced according to the SOC value of the single battery needing to be balanced, the reference value of the SOC and the balancing duty ratio.

8. The method according to any one of claims 1-7, further comprising:

determining the target number of balancing resistors which need to be connected with the single batteries needing to be balanced in parallel according to the balancing current;

and controlling the target number of balancing resistors to be connected in parallel with the single batteries needing balancing.

9. The method according to any one of claims 1-7, further comprising:

determining the resistance value of the balancing resistor which needs to be connected in parallel with the single battery needing to be balanced according to the balancing current;

determining a target balancing resistor which needs to be connected with the single battery needing balancing in parallel according to the determined resistance value and the resistance value of each balancing resistor which can be connected in parallel;

and controlling the target balancing resistance to be connected with the single battery needing balancing in parallel.

10. The method according to any one of claims 1-7, further comprising:

in the balancing process of the single battery cells needing balancing, when detecting that any performance parameter of the single battery cells needing balancing meets a balancing current adjusting condition corresponding to the performance parameter, adjusting the balancing current of the single battery cells needing balancing, wherein the performance parameters at least comprise: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate, and time change rate.

11. The method according to claim 10, wherein the adjusting the balancing current of the single battery cell to be balanced comprises:

when the difference value between the performance parameter value of the single battery needing to be balanced and the reference value of the performance parameter is larger than the difference value at the beginning of balancing, performing increased adjustment on the balancing current of the single battery needing to be balanced, wherein the reference value is the maximum value, the minimum value or the average value of the performance parameter value of each single battery in the battery pack;

and when the difference value between the performance parameter value of the single battery needing to be balanced and the reference value of the performance parameter is smaller than the difference value at the beginning of balancing, performing reduced adjustment on the balancing current of the single battery needing to be balanced.

12. A battery equalization system, comprising: the device comprises a balancing module, an acquisition module and a control module;

the control module is used for determining the single batteries needing to be balanced in the battery pack according to the battery information of each single battery of the battery pack, which is acquired in the sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and the balancing time period; acquiring a value of a performance parameter of the single battery needing to be balanced and a reference value of the performance parameter according to battery information of each single battery, wherein the performance parameter is any one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate and time change rate; determining the balancing current of the single battery to be balanced according to the value of the performance parameter of the single battery to be balanced, the reference value of the performance parameter and a preset balancing duty ratio, wherein the balancing duty ratio is the ratio of the duration of the balancing time period to the duration of the unit period; controlling the balancing of the single batteries needing balancing in the balancing time period of the unit cycle according to the balancing current;

the balancing module is used for balancing the corresponding single batteries under the control of the control module;

the control module is further configured to determine a difference between a value of a performance parameter of at least one cell and a reference value of the performance parameter; and determining the single battery of which the difference value between the value of the performance parameter and the reference value of the performance parameter is greater than or equal to the equalization starting threshold value in at least one single battery as the single battery needing equalization.

13. The system of claim 12, wherein the control module is configured to determine one of the single batteries to be equalized as a reference battery to be equalized; and determining the balancing current of the single battery needing to be balanced according to the value of the performance parameter of the reference battery to be balanced, the reference value and the preset balancing duty ratio.

14. The system of claim 12, wherein the performance parameter is voltage;

15. The system of claim 14, wherein the control module is configured to determine a reference OCV value of the reference battery based on the voltage value of the reference battery and an internal resistance value of the reference battery; determining an SOC value corresponding to the reference OCV value as the first SOC value according to the reference OCV value and an OCV-SOC curve of the reference battery; and

16. The system of claim 15, wherein the control module is configured to control the power converter according to Δ Q = Δ SOC × C _n Determining a difference in electrical quantities, where Δ Q is the difference in electrical quantities, Δ SOC is a difference in SOC between the first and second SOC values, and C _n The available capacity of the single battery needing to be balanced is obtained; and determining the balancing current of the single battery needing balancing according to I = delta Q/(t multiplied by tau), wherein t is preset balancing duration of the single battery, I is the balancing current, and tau is the balancing duty ratio.

17. The system of claim 12, wherein the performance parameter is voltage;

18. The system according to claim 12, wherein the performance parameter is SOC, and the reference value of SOC is a minimum voltage value, a maximum voltage value, or an average voltage value among SOC values of the respective unit cells;

19. The system according to any one of claims 12 to 18, wherein the control module is further configured to determine a target number of balancing resistors to be connected in parallel with the single battery to be balanced according to the balancing current; and controlling the target number of balancing resistors to be connected in parallel with the single batteries needing balancing.

20. The system according to any one of claims 12 to 18, wherein the control module is further configured to determine, according to the balancing current, a resistance value of a balancing resistor that needs to be connected in parallel to the single battery that needs to be balanced; determining a target balancing resistor which needs to be connected with the single battery needing balancing in parallel according to the determined resistance value and the resistance value of each balancing resistor which can be connected in parallel; and controlling the target balancing resistance to be connected with the single battery needing balancing in parallel.

21. The system according to any one of claims 12 to 18, wherein the control module is further configured to, during the balancing process of the single battery cell requiring balancing, adjust the balancing current of the single battery cell requiring balancing when it is detected that any one of performance parameters of the single battery cell requiring balancing satisfies a balancing current adjustment condition corresponding to the performance parameter, where the performance parameter at least includes: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate, and time change rate.

22. The system according to claim 12, wherein the control module is connected with the acquisition module and the equalization module corresponding to the same single battery through a channel, and the control module is configured to control the control module to be connected with the corresponding sampling module when it is determined that the single battery connected with the control module does not need equalization; alternatively, the first and second electrodes may be,

the control module is also used for multiplexing the channel in a time-sharing manner by the acquisition module and the balancing module when the single battery connected with the control module is determined to need balancing; the control module is connected with the acquisition module and the balance module corresponding to the same single battery through a channel, and the acquisition module and the balance module multiplex the channel in a time-sharing manner.

23. The system of claim 22, wherein the control module comprises a control chip, and the control chip is connected with the acquisition module and the equalization module corresponding to the same cell through one pin and the one channel.

24. The system of claim 12, wherein the control module is connected to the collection module and the equalization module corresponding to the same cell through two channels.

25. The system according to claim 24, wherein the control module comprises a control chip, the control chip is connected to the acquisition module and the equalization module corresponding to the same cell through two pins, and the two pins are in one-to-one correspondence with the two channels.

26. A vehicle comprising a battery equalization system as claimed in any of claims 12-25.

27. A computer-readable storage medium, on which computer program instructions are stored, which program instructions, when executed by a processor, implement the method of any one of claims 1-11.

28. An electronic device, comprising: the computer-readable storage medium recited in claim 27; and one or more processors for executing the program in the computer-readable storage medium.