CN109435770A

CN109435770A - Battery equalization method, system, vehicle, storage medium and electronic equipment

Info

Publication number: CN109435770A
Application number: CN201710773506.XA
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: 2019-03-08
Anticipated expiration: 2037-08-31
Also published as: CN109435770B

Abstract

This disclosure relates to a kind of battery equalization method, system, vehicle, storage medium and electronic equipment, the battery equalization method includes: the battery information of each single battery of the battery pack obtained in the sampling periods according to unit period, the internal resistance value of each single battery is obtained, unit period includes sampling periods and balancing period；According to the internal resistance value of each single battery, determines and refer to internal resistance value；According to the internal resistance value of the single battery to be equalized in battery pack and internal resistance value is referred to, determines that the balanced duty ratio of single battery to be equalized, balanced duty ratio are the ratio of the duration of balancing period and the duration of unit period；According to the balanced duty ratio, the equilibrium of the single battery to be equalized is controlled in the balancing period of unit period.By the disclosure, battery information acquisition and balanced timesharing are carried out, thus the battery information acquired is more accurate, and portfolio effect is preferable；And carried out in equilibrium according to its balanced duty ratio, equalization 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 battery management technologies, and in particular, to a battery balancing method, a battery balancing system, a vehicle, a storage medium, and an electronic device.

Background

The battery pack is an important component of the electric vehicle. With the use of the battery pack, the difference between the single batteries in the battery pack gradually expands, so that the consistency between the single batteries is poor. Due to the "short plate effect" of the battery pack, the capacity exertion of the battery pack is limited, resulting in a reduction in the overall capacity of the battery pack. Therefore, it is necessary to perform effective balance management on the single batteries in the battery pack to keep the capacities of the single batteries consistent, so as to reduce the capacity loss of the battery pack, and prolong the service life of each single battery and the driving range of the electric vehicle.

At present, balance management is performed on a power battery pack, and a single battery needing to be balanced is determined from the power battery pack, so that battery information of each single battery in the power battery pack needs to be collected in real time, and then, which single batteries need to be balanced is determined according to the battery information, and further, the single batteries needing to be balanced are balanced. However, in such a manner, equalization may be performed while collecting battery information, which may result in inaccurate collected battery information and poor equalization effect.

Disclosure of Invention

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

According to a first aspect of the embodiments of the present disclosure, there is provided a battery equalization method, including:

acquiring the internal resistance value of each single battery according to the battery information of each single battery of the battery pack acquired in the sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and the balancing time period;

determining a reference internal resistance value according to the internal resistance value of each single battery;

determining the balancing duty ratio of the single battery to be balanced according to the internal resistance value of the single battery to be balanced in the battery pack and the reference internal resistance value, wherein the balancing duty ratio is the ratio of the time length of the balancing time period to the time length of the unit period;

and balancing the single batteries to be balanced in the balancing time period of the unit cycle according to the balancing duty ratio.

According to a second aspect of the embodiments of the present disclosure, there is provided a battery equalization system including: 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 acquiring the internal resistance value of each single battery according to the battery information of each single battery of the battery pack, which is acquired in the sampling period of a unit cycle, wherein the unit cycle comprises the sampling period and the balancing period; determining a reference internal resistance value according to the internal resistance value of each single battery; determining the balancing duty ratio of the single battery to be balanced according to the internal resistance value of the single battery to be balanced in the battery pack and the reference internal resistance value, wherein the balancing duty ratio is the ratio of the duration of the balancing time period to the duration of the unit period; according to the balance duty ratio, controlling the balance of the single battery to be balanced in the balance time period of the unit cycle;

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

According to a third aspect of the embodiments of the present disclosure, there is provided a vehicle including the battery equalization system provided by the second aspect of the embodiments of the present disclosure.

According to a fourth aspect of the embodiments of the present disclosure, there is provided a computer-readable storage medium having stored thereon computer program instructions which, when executed by a processor, provide a battery equalization method according to the first aspect of the embodiments of the present disclosure.

According to a fifth aspect of embodiments of the present disclosure, there is provided an electronic apparatus including:

a computer-readable storage medium provided by a fourth aspect of the embodiments of the present disclosure; and

one or more processors to execute the program in the computer-readable storage medium.

Through the technical scheme, the battery information acquisition and the equalization are carried out in a time-sharing manner, so that the acquired battery information is more accurate and the equalization effect is better; on the other hand, after the balance duty ratio of the single battery to be balanced is determined, the duration of the sampling period and the duration of the balance period are controlled under the condition of unit cycle setting according to the balance duty ratio, so that the balance efficiency can be improved, and the balance cost can be reduced.

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 illustrating a configuration of a battery equalization system according to an exemplary embodiment;

FIG. 2 is a flow chart illustrating a method of battery equalization in accordance with an exemplary embodiment;

fig. 3 is a flowchart illustrating a method of obtaining an internal resistance value of a unit battery according to an exemplary embodiment;

FIG. 4 is a flow chart illustrating a method of determining an equalized duty cycle in accordance with an exemplary embodiment;

FIG. 5 is an OCV-SOC curve for a single cell;

FIG. 6 is a block diagram illustrating an equalization module in accordance with an exemplary embodiment;

FIG. 7A is a flow chart illustrating a method of battery equalization in accordance with another exemplary embodiment;

FIG. 7B is a flow chart illustrating a method of battery equalization in accordance with another exemplary embodiment;

FIG. 7C is a flow chart illustrating a method of battery equalization in accordance with another exemplary embodiment;

fig. 8A to 8B are schematic structural views illustrating a battery equalization system according to an exemplary embodiment;

fig. 9A to 9C are schematic structural views illustrating a battery equalization system according to another exemplary embodiment.

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, and are not intended to limit the present disclosure.

It should be noted that the terms "first," "second," and the like in the description and claims of the present disclosure and in the above-described drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

Fig. 1 is a schematic diagram illustrating a configuration of a battery equalization system according to an exemplary embodiment. As shown in fig. 1, the battery equalization system 10 includes: the system comprises a battery pack 11, an acquisition module 12, an equalization module 13 and a control module 14. The battery pack 11 includes a plurality of unit cells connected in series.

The work flow of the battery balancing system for balancing the single batteries in the battery pack is as follows: the control module 14 controls the collecting module 12 to collect battery information of each battery cell in the battery pack 11, wherein the battery information may include at least one of the following information: voltage, current, and temperature, etc. The control module 14 determines whether a single battery in the battery pack needs to be balanced according to the battery information of each single battery, and controls the balancing module 13 to perform balancing processing on the single battery to be balanced after determining the single battery to be balanced.

Fig. 2 is a flow chart illustrating a method of battery equalization in accordance with an exemplary embodiment. As shown in fig. 2, the battery equalization method includes the following steps:

in step S21, the internal resistance value of each cell is acquired from the battery information of each cell of the battery pack acquired in the sampling period of the unit cycle, which includes the sampling period and the equalization period.

And in the sampling period of the unit cycle, the control module controls the acquisition module to acquire the battery information of each single battery in the battery pack respectively. Wherein, the battery information may for example comprise at least one of the following information: voltage, current, and temperature. At this point, the equalization module stops operating.

And in the balancing time period of the unit cycle, the control module controls the balancing module to balance the module to be balanced in the battery pack. At this point, the acquisition module stops working.

In one embodiment, as shown in fig. 3, the step S21 includes:

in step S211, for each unit cell in the battery pack, an initial voltage value and an initial current value of the unit cell before entering a constant current condition are determined.

In step S212, the voltage value and the current value of the unit cell under the constant current condition are determined.

In one embodiment, whether the single battery enters a constant-current working condition is detected, and after the single battery enters the constant-current working condition and the constant-current working condition lasts for a preset time, the voltage value and the current value of the single battery under the constant-current working condition are determined.

In one embodiment, the current of the single battery in a given time period can be collected, and when the current change amplitude of the single battery in the given time period is smaller than a preset change amount, the single battery can be determined to enter a constant current working condition.

In step S213, it is determined that the internal resistance value of the single battery is the ratio of the voltage difference value to the current difference value according to the voltage difference value between the initial voltage value and the voltage value of the single battery under the constant current condition, and the current difference value between the initial current value and the current value of the single battery under the constant current condition.

In one embodiment, the internal resistance value of the unit cell may be determined according to equation (1).

Wherein R is the internal resistance value of the single battery, V₀Is the initial voltage value of the single battery before the single battery enters the constant current working condition, I₀The initial current value V of the single battery before the single battery enters the constant current working condition_nThe voltage value of the single battery under the constant current working condition, I_nAnd the current value of the single battery under the constant current working condition is shown.

In step S22, a reference internal resistance value is determined based on the internal resistance values of the respective unit cells.

In one embodiment, the internal resistance value of any single battery in the battery pack may be used as the reference internal resistance value, for example, the internal resistance value of the 2 nd single battery in the battery pack may be used as the reference internal resistance value.

In another embodiment, the reference internal resistance value may be calculated based on the internal resistance values of the respective unit cells in the battery pack. For example, the minimum internal resistance value among the internal resistance values of the respective unit cells in the battery pack may be determined as a reference internal resistance value; or determining the maximum internal resistance value of the internal resistance values of the single batteries in the battery pack as a reference internal resistance value; alternatively, an average value of the internal resistance values of the respective unit cells in the battery pack is determined as the reference internal resistance value.

In step S23, a balancing duty ratio of the single battery to be balanced is determined according to the internal resistance value and the reference internal resistance value of the single battery to be balanced in the battery pack, where the balancing duty ratio is a ratio of a duration of the balancing period to a duration of the unit period.

In one embodiment, the balancing duty ratio of the single battery to be balanced may be determined according to a preset corresponding relationship between the internal resistance difference and the balancing duty ratio between the internal resistance value of the single battery to be balanced and the internal resistance difference of the reference internal resistance value. The corresponding relation between the internal resistance difference value and the balance duty ratio can be set according to multiple tests or experiences.

Table 1 provides an example of a correspondence relationship between the internal resistance difference value and the equalizing duty ratio.

TABLE 1

Difference of internal resistance	Equalizing duty cycle
		[R₁,R₂)	τ₁
[R₂,R₃)	τ₂
		……	……
[R_n-1,R_n)	τ_n

In another embodiment, as shown in fig. 4, the method for determining the balancing duty ratio of the single battery to be balanced according to the internal resistance value of each single battery and the reference internal resistance value may include the following steps:

in step S231, the unit cell of the battery pack having the smallest difference between the internal resistance value and the reference internal resistance value is determined as the reference cell.

After the internal resistance value of each single battery is determined, the internal resistance value of each single battery is compared with the reference internal resistance value, and the single battery with the minimum difference between the internal resistance value and the reference internal resistance value is used as the reference battery.

In step S232, a first SOC value corresponding to the reference internal resistance value is determined according to the reference internal resistance value, the voltage value of the reference battery, the current value of the reference battery, and the open-circuit voltage OCV-remaining capacity SOC curve corresponding to the reference battery.

In one embodiment, the reference OCV value of the reference battery may be determined according to the reference internal resistance value, the voltage value of the reference battery, and the current value of the reference battery, i.e., the reference OCV value is the voltage value of the reference battery + the reference internal resistance value × the current value of the reference battery.

Since different unit batteries correspond to different OCV-SOC curves, as shown in fig. 5, after the reference OCV value is determined, the SOC value corresponding to the reference OCV value may be determined as the first SOC value according to the reference OCV value and the OCV-SOC curve of the reference battery.

In step S233, a second SOC value corresponding to the battery cell to be equalized is determined according to the internal resistance value of the battery cell to be equalized, the voltage value of the battery cell to be equalized, the current value of the battery cell to be equalized, and the OCV-SOC curve corresponding to the battery cell to be equalized.

In one embodiment, the OCV value of the balancing cell may be determined according to the internal resistance value of the cell to be balanced, the voltage value of the balancing cell, and the current value of the balancing cell, that is, the OCV value of the balancing cell is equal to the voltage value of the balancing cell + the internal resistance value of the balancing cell × the current value of the balancing cell.

The internal resistance value of the single battery may be preset, or the internal resistance value of the single battery may be determined according to the voltage and the capacity of the single battery. 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.

Since different unit cells correspond to different OCV-SOC curves, as shown in fig. 5, after the reference OCV value is determined, the SOC value corresponding to the OCV value of the balancing unit cell may be determined as the second SOC value according to the obtained OCV value of the balancing unit cell and the OCV-SOC curve of the balancing unit cell.

In step S234, an equalization duty ratio of the cell to be equalized is determined according to the first SOC value and the second SOC value.

In one embodiment, after determining the first SOC value and the second SOC value, Δ Q may be expressed as Δ SOC × C_nDetermining the electric quantity difference, wherein delta Q is the electric quantity difference between the reference battery and the single battery to be balanced, delta SOC is the SOC difference value between the first SOC value and the second SOC value, C_nIs the available capacity of the single battery to be equalized.

And then, determining the balance duty ratio of the single battery to be balanced according to the condition that tau is (delta Q/I)/t, wherein t is the preset balance time of the single battery to be balanced, I is the preset balance current of the single battery to be balanced, and tau is the balance duty ratio of the single battery to be balanced.

In step S24, the cell to be equalized is equalized in the equalization period of the unit cycle in accordance with the equalization duty ratio.

According to the balance duty ratio of the single batteries to be balanced, the time length of the balance time period of the unit period can be determined, and the balance module is controlled to process the single batteries to be balanced in the balance time periods of one or more unit periods according to the time length of the balance time period until the accumulated balance time length reaches the preset balance time length.

It should be noted that, according to different ways of determining the reference internal resistance value, different ways may be adopted to perform the balancing process on the single battery to be balanced. Next, different equalization processing methods will be described.

The first method is as follows: and passive equalization.

If the minimum internal resistance value of the internal resistance values of the single batteries in the battery pack is determined as the reference internal resistance value, the balancing module can be controlled to perform balancing processing on the single batteries to be balanced in a passive balancing mode, namely, the single batteries to be balanced are discharged. For example, a resistor connected in parallel with the single battery to be balanced is arranged in the balancing module, and in the balancing time period of a unit cycle, the control module controls the conduction of a parallel loop between the single battery to be balanced and the corresponding resistor, so as to perform passive balancing on the single battery, and achieve the effect of balancing each single battery in the battery pack. Referring to fig. 6, the control module is turned on by controlling the switch 813, so as to achieve the conduction of the parallel loop between the single battery to be equalized and the corresponding resistor 812.

Resistor 812 may be a fixed value resistor or a variable resistor. In one embodiment, the resistor 812 may be a thermistor with a positive temperature coefficient, and the resistance value of the thermistor may change with the change of temperature, so as to adjust the equalizing current generated during equalization, thereby automatically adjusting the heat generation amount of the battery equalization system, and finally, effectively controlling the temperature of the battery equalization system.

The second method comprises the following steps: and (4) active equalization.

If the maximum internal resistance value of the internal resistance values of the single batteries in the battery pack is determined as the reference internal resistance value, the balancing module can be controlled to perform balancing processing on the single batteries to be balanced in an active balancing mode, namely, the single batteries to be balanced are charged, so that the effect of balancing the single batteries in the battery pack is achieved.

For example, as shown in fig. 6, a charging branch 94 connected in parallel with the single battery to be equalized is provided in each equalizing module, and the charging branch 94 is connected to a generator 92, and the generator 92 is mechanically connected with an engine 91 through a gear.

For the single battery to be equalized which needs to be actively equalized, the control module controls the charging branch 94 corresponding to the single battery to be equalized 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 output to the single battery to be balanced, and the electricity of the single battery to be balanced is increased.

Referring to fig. 6, when the generator 92 is an alternator, the equalizing 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 battery to be equalized.

Referring to fig. 6, the control module may control the switch 96 corresponding to the single battery to be equalized to be turned on, so that the charging branch corresponding to the single battery to be equalized is turned on, and active equalization of the single battery to be equalized is performed.

In other embodiments, in addition to the charging of the single batteries by the generator shown in fig. 6, 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 to be equalized as shown in fig. 6, the single battery to be equalized may be connected in parallel with a starting battery of the whole vehicle, and the electric quantity discharged by the single battery to be equalized is charged into the starting battery, so that the equalization of the single battery to be equalized is realized while energy waste is effectively avoided.

The third method comprises the following steps: passive equalization is combined with active equalization.

If the average value of the internal resistance values of the single batteries in the battery pack is determined as the reference internal resistance value, the balancing module can be controlled to perform balancing processing on the single batteries to be balanced in an active balancing mode, namely, the single batteries to be balanced with the internal resistance values larger than the reference internal resistance value adopt a passive balancing mode, and the single batteries to be balanced with the internal resistance values smaller than the reference internal resistance value adopt an active balancing mode, so that the internal resistance difference value between the internal resistance value of each single battery to be balanced and the reference internal resistance value is reduced to be within a preset range, and the balancing effect of each single battery in the battery pack is achieved.

In another embodiment, as shown in fig. 7A, the above battery balancing method further includes:

in step S25, in the balancing process of the cell to be balanced, the balancing current of the cell to be balanced is acquired.

In the balancing process of the single battery to be balanced, the balancing current of the single battery to be balanced may change, for example, when the single battery to be balanced adopts passive balancing (discharging), the resistance value of the balancing resistor connected in parallel with the single battery to be balanced in the balancing module may change, so that the balancing current of the single battery to be balanced changes, and if the single battery to be balanced is still balanced according to the preset balancing duty ratio, the balancing time is easily overlong.

Therefore, the balancing current of the single battery to be balanced can be monitored in the balancing process of the single battery to be balanced, and the balancing duty ratio of the single battery to be balanced can be adjusted according to the balancing current.

In one embodiment, taking a passive balancing manner for the single battery to be balanced as an example, a detection resistor with a smaller resistance value may be connected in series to the balancing resistor, and a current value of the detection resistor, that is, a balancing current of the single battery to be balanced, may be obtained by detecting a voltage value at two ends of the detection resistor.

In step S26, when the balancing current is greater than or equal to the preset balancing current, the balancing duty ratio of the single battery to be balanced is reduced.

When the equalizing current of the single battery to be equalized is greater than or equal to the preset equalizing current, the equalizing time required by the single battery to be equalized is reduced, and the time of the sampling time period is increased, so that the sampling frequency is increased, the real-time performance of the acquired battery information of the single battery to be equalized is improved, the control module can timely and accurately judge the equalizing state of the single battery to be equalized, and the real-time monitoring of the single battery is enhanced.

In step S27, when the balancing current is less than the preset balancing current, the balancing duty ratio of the unit cells to be balanced is increased.

When the equalizing current of the single battery to be equalized is smaller than the preset equalizing current, the equalizing duty ratio of the single battery to be equalized can be increased, so that the duration of the equalizing time period of the unit period is increased, and the equalizing speed of the single battery to be equalized can be increased.

In another embodiment, as shown in fig. 7B, the above battery balancing method further includes:

in step S28, in the balancing process of the single battery cell to be balanced, when it is detected that any one of the performance parameters of the single battery cell to be balanced satisfies the balancing duty ratio adjustment condition corresponding to the performance parameter, the balancing duty ratio of the single battery cell to be balanced is adjusted, where the performance parameter at least includes: voltage, SOC value, internal resistance, self-discharge rate, voltage change rate, charge change rate, and time change rate.

In the embodiment of the present disclosure, the self-discharge rate of the unit cell refers to the capacity of the unit cell to retain the stored charge under certain conditions when the unit cell is in an open circuit state (i.e., stops charging or discharging). The self-discharge rate of the single battery is an important parameter for representing the characteristics of the single battery, and the capacity loss condition and the capacity loss rate of the single battery can be effectively represented.

The voltage change rate of the unit cells may be a voltage change rate of the unit cells during charging (or discharging), that is, 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, the 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 will be described as an example.

The rate of change in the amount of charge of the unit cells may be a voltage change amount at which a unit 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.

And in the sampling period of the unit cycle, determining each performance parameter of the single battery to be balanced according to the acquired battery information of the single battery to be balanced, judging whether the performance parameter meets a corresponding balancing duty ratio adjusting condition, and if so, adjusting the balancing duty ratio.

Taking the performance parameter including voltage as an example, in one embodiment, when the battery pack is in a charging state, the equalizing duty ratio adjustment condition is: the voltage value of the single battery to be balanced in the balancing process is higher than a first preset high-voltage threshold value or higher than a second preset high-voltage threshold value.

Correspondingly, when the battery pack is in a charging state, if the voltage value of the single battery to be equalized in the equalizing process is higher than a first preset high-voltage threshold, the equalizing duty ratio is reduced, so that the time length of the equalizing time period is reduced, the time length of the sampling time period is increased, the sampling frequency can be increased, the real-time performance of the collected battery information of the single battery to be equalized is improved, the control module can timely and accurately judge the equalizing state of the single battery to be equalized, the problem of overcharging of the single battery to be equalized is avoided, and the real-time monitoring of the single battery is enhanced; if the voltage value of the single battery to be balanced in the balancing process is higher than a second preset high-voltage threshold, the balancing duty ratio is adjusted to be 0, namely, the balancing of the single battery to be balanced is stopped, so that the safety of the single battery to be balanced is ensured.

In another embodiment, when the battery pack is in a discharge state, the equalization duty ratio adjustment condition is: the voltage value of the single battery to be balanced in the balancing process is lower than a first preset low-voltage threshold value or lower than a second preset low-voltage threshold value.

Correspondingly, when the battery pack is in a discharging state, if the voltage value of the single battery to be equalized in the equalizing process is lower than a first preset low-voltage threshold, the equalizing duty ratio is reduced, the sampling frequency can be increased, so that the real-time performance of the acquired battery information of the single battery to be equalized is improved, the control module can timely and accurately judge the equalizing state of the single battery to be equalized, the problem of overdischarging of the single battery to be equalized is avoided, and the real-time monitoring of the single battery is enhanced.

If the voltage value of the single battery to be balanced in the balancing process is lower than a second preset low-voltage threshold value, the balancing duty ratio is adjusted to be 0, namely, the balancing of the single battery to be balanced is stopped, so that the safety of the single battery to be balanced is ensured.

Fig. 7C is a flow chart illustrating a method of cell balancing according to another exemplary embodiment. As shown in fig. 7C, the battery equalization method includes the steps of:

in step S71, the single battery to be equalized is determined from the battery pack according to the performance parameters of each single battery in the battery pack, where the performance parameters include at least one of voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate, and time change rate.

After the acquisition module acquires battery information (including a load voltage value, a current value and a temperature value, for example) of each single battery in the battery pack, the control module can obtain performance parameters of each single battery according to the battery information of each single battery, and determine the single batteries needing to be balanced in the battery pack according to the performance parameters of each single battery.

For example, taking the example that the performance parameter includes a voltage value (open circuit voltage value), the voltage value of each unit cell can be obtained from the battery information of each unit cell. And then, determining a reference voltage value according to the voltage value of each single battery, and determining the single batteries to be balanced according to the voltage value of each single battery and the reference voltage value.

Alternatively, the minimum voltage value of the voltage values of the single batteries in the battery pack may be determined as the reference voltage value, and accordingly, the single battery with the voltage value greater than the reference voltage value in the battery pack may be determined as the single battery to be equalized.

Alternatively, the maximum voltage value of the voltage values of the single batteries in the battery pack may be determined as the reference voltage value, and accordingly, the single battery with the voltage value smaller than the reference voltage value in the battery pack may be determined as the single battery to be equalized.

Alternatively, an average voltage value of the voltage values of the single batteries in the battery pack may be determined as a reference voltage value, and accordingly, the single batteries in the battery pack, of which the voltage values are greater than the reference voltage value or less than the reference voltage value, may be determined as the single batteries to be equalized.

Alternatively, the voltage value of any single battery in the battery pack may be used as a reference voltage value, and accordingly, the single battery in the battery pack with the voltage value greater than the reference voltage value or less than the reference voltage value may be determined as the single battery to be equalized.

It should be understood that, referring to the following table 2, when the performance parameters are SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate, or time change rate, respectively, the correspondence relationship between the equalization judgment and the equalization manner.

TABLE 2

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 2, and the single batteries to be equalized 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 S71 that there is no cell that needs to be equalized, the determination of equalization continues based on the information collected at the next sampling period. When it is determined that there is no single battery needing to be equalized according to the information acquired at the sampling time period, the control module may not act at the equalization time period, so that the equalization module corresponding to any single battery is not started.

In step S72, the internal resistance value of each cell is acquired from the battery information of each cell of the battery pack acquired in the sampling period of the unit cycle, which includes the sampling period and the equalization period.

In step S73, a reference internal resistance value is determined based on the internal resistance values of the respective unit cells.

In step S74, a balancing duty ratio of the single battery to be balanced is determined according to the internal resistance value and the reference internal resistance value of the single battery to be balanced in the battery pack, where the balancing duty ratio is a ratio of a duration of the balancing period to a duration of the unit period.

In step S75, the cell to be equalized is equalized in the equalization period of the unit cycle in accordance with the equalization duty ratio.

Fig. 8A is a schematic structural diagram illustrating a battery equalization system according to an exemplary embodiment, and fig. 9A is a schematic structural diagram illustrating a battery equalization system according to another exemplary embodiment. As shown in fig. 8A and 9A, the battery equalization system 80 includes: a battery pack 81, an acquisition module 82, an equalization module 83, and a control module 84. The battery pack 81 includes a plurality of unit cells 811 connected in series.

In the battery equalization system 80 shown in fig. 8A, the control module 84 is connected to the acquisition module 82 and the equalization module 83 corresponding to the same battery cell 811 through two channels 810, 820, respectively.

The control module 84 may include a control chip, and the control chip is connected to the acquisition module 82 and the balancing module 83 corresponding to the same battery cell through two pins, which correspond to the two channels one to one.

In this embodiment, the control module 84 controls the acquisition module 82 and the balancing module 83 to conduct in a time-sharing manner according to the unit cycle, and respectively performs the acquisition of the battery information and the balancing of the battery, so that the acquisition and the balancing of the battery information 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, as shown in fig. 8A, each cell in the battery pack is connected to an acquisition module 82 and an equalization module 83, respectively. If the battery pack includes N single batteries, the number of the acquisition modules 82 is N, and the number of the equalization modules 83 is N, so that the control module 84 is connected to each acquisition module 82 and each equalization module 83 through 2 × N channels.

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 per a 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.

Referring to fig. 8B, two cells share one equalizing module 83, and when two cells sharing one equalizing module 83 need to be equalized, the equalizing module 83 is alternately connected to each cell during an equalizing period of a unit cycle. The alternate connection may be a connection that alternates according to a certain period. For example, referring to fig. 8B, when the parallel switch 850 on the parallel branch 85 corresponding to one battery cell 811 of the two battery cells is closed for 2s under the control of the control module 84, the parallel switch 850 on the parallel branch 85 corresponding to the other battery cell 811 of the two battery cells is opened for 2s under the control of the control module 84. I.e., the parallel switch 850 on the parallel branch 85 corresponding to each of the two unit cells 811, is switched from the closed state to the open state or from the open state to the closed state every 2s during the equalization period. Therefore, on the basis of time-sharing conduction of the acquisition module 82 and the equalization module 83, the single batteries sharing the same equalization module 83 are alternately connected with the shared equalization module 83 during an equalization period, so that equalization is realized.

In the battery equalization system 80 shown in fig. 9A, the control module 84 is connected to the acquisition module 82 and the equalization module 83 corresponding to the same battery cell 811 through a channel 830.

The control module 84 is configured to control the control module 84 to be connected to the corresponding acquisition module 82 when it is determined that the cell connected to the control module 84 does not need to be balanced; or, the control module 84 is further configured to time-division multiplex the channel 830 according to a unit cycle by the acquisition module 82 and the equalization module 83 when it is determined that the cell connected to the control module 84 needs to be equalized.

In one embodiment, control module 84 includes a control chip that is connected to acquisition module 82 and equalization module 83 corresponding to the same cell via one pin and one channel.

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 when the battery information acquisition and the balancing are performed simultaneously is avoided; on the other hand, compared with the embodiment shown in fig. 8A, the requirement for the number of channels of the control module chip is reduced, and the hardware cost can be saved.

In one embodiment, as shown in fig. 9B, a switch K1 is disposed in the channel 830 shared by the acquisition module 82 and the equalization module 83, and the control module 84 is connected to the switch K1 and connected to the acquisition module 82 or the equalization module 83 in a time-sharing manner by controlling the switch K1. When the switch K1 is connected to the collection module 82, the control module 84 controls the collection module 82 to collect battery information of the single battery in a sampling period; when the switch K1 is connected to the balancing module 83, the control module 84 controls the balancing module 83 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 gathering with balanced through regulating switch's state to not sampling when can realizing equal weighing apparatus, the effect of imbalance during the sampling, thereby balanced electric current can not influence battery voltage, thereby precision when having improved battery voltage sampling.

In other embodiments, different cells may share the equalization module 83, for example, N cells in a battery pack, the same equalization module may be shared, or the same equalization module 83 may be shared for every predetermined number (e.g., 2, 3, or 5, etc.) of cells, and so on. When at least two of the plurality of unit cells sharing one balancing module 83 need to be balanced, the balancing module 83 is alternately connected to each of the at least two unit cells needing to be balanced in the balancing period of the unit cycle.

Fig. 9C is an exemplary diagram of two unit cells sharing one balancing module. Referring to fig. 9C, when two unit cells sharing one balancing module need to be balanced, the balancing module is alternately connected to each unit cell during the balancing period 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 balancing module, the single batteries sharing the same balancing module are alternately connected with the shared balancing module during the balancing time period, and balance is realized.

In one embodiment, the collecting module comprises a voltage collecting chip, and the voltage collecting chip is used for collecting the voltage of the single battery in the sampling time period. 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, so as to control the acquisition module to acquire parameter information of single batteries in the battery pack. The second control unit can also send an acquisition instruction to the first control unit through the communication unit so as to control the connecting channel to be connected to the acquisition module through the first control unit.

The first control unit can be connected to the balancing module by controlling the connection channel, so as to control the balancing module to perform balancing processing on the single battery 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 single batteries 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 balancing 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 balancing module of the same single battery correspond to one connecting 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. That is, 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. And 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 in the preset time length, 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 and balanced 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.

In the embodiment of the present disclosure, the unit cycle is divided into the sampling period and the equalization period, and a ratio of a duration of the equalization period to a duration of the unit cycle is an equalization duty ratio. According to the battery balancing method, after the balancing duty ratio of the single battery to be balanced which needs to be balanced is determined, the balancing of the single battery 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. As shown in fig. 8A to 8B and fig. 9A to 9C, the collecting module 82 is configured to collect battery information of each battery cell 811 of the battery pack 81 in a sampling period of a unit cycle under the control of the control module 84.

The control module 84 is configured to obtain an internal resistance value of each single battery according to battery information of each single battery of the battery pack, which is obtained in a sampling period of a unit cycle, where the unit cycle includes the sampling period and a balancing period; determining a reference internal resistance value according to the internal resistance value of each single battery; determining the balancing duty ratio of the single battery to be balanced according to the internal resistance value of the single battery to be balanced in the battery pack and the reference internal resistance value, 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 balancing of the single batteries to be balanced in the balancing time period of the unit cycle according to the balancing duty ratio.

And the balancing module 83 is configured to balance the corresponding single batteries under the control of the control module 84.

In one embodiment, the control module 84 is configured to determine the balancing duty ratio of the single battery to be balanced according to an internal resistance difference between the internal resistance value of the single battery to be balanced and the reference internal resistance value, and a preset corresponding relationship between the internal resistance difference and the balancing duty ratio.

In another embodiment, the control module 84 is configured to determine a single battery in the battery pack with the smallest difference between the internal resistance value and the reference internal resistance value as a reference battery; determining a first SOC value corresponding to the reference internal resistance value according to the reference internal resistance value, the voltage value of the reference battery, the current value of the reference battery and an open-circuit voltage OCV-remaining capacity SOC curve corresponding to the reference battery; determining a second SOC value corresponding to the internal resistance value of the single battery to be balanced according to the internal resistance value of the single battery to be balanced, the voltage value of the single battery to be balanced, the current value of the single battery to be balanced and the OCV-SOC curve corresponding to the single battery to be balanced; and determining the balance duty ratio of the single battery to be balanced according to the first SOC value and the second SOC value.

In another embodiment, the control module 84 is configured to determine a reference OCV value of the reference battery according to the reference internal resistance value, the voltage value of the reference battery, and the current 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 an OCV value of the single battery to be balanced according to the internal resistance value of the single battery to be balanced, the voltage value of the single battery to be balanced and the current value of the single battery to be balanced; and determining the SOC value corresponding to the OCV value of the single battery to be balanced as the second SOC value according to the OCV-SOC curve of the single battery to be balanced.

In another embodiment, the control module 84 is configured to control the operation of the motor according to Δ Q ═ Δ SOC × C_nDetermining 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_nThe available capacity of the single battery to be balanced is obtained; determining the balancing duty ratio of the single battery to be balanced according to the condition that tau is (delta Q/I)/t, wherein t is preset balancing duration of the single battery to be balanced, I is preset balancing current of the single battery to be balanced, and tau is the balancing duty ratio. Presetting the equalizing current, possibly according to the resistance of the equalizing moduleThe resistance value, the current that the engine can provide when balancing the battery, etc., or set according to the actual balancing requirements.

In another embodiment, the control module 84 is further configured to obtain an equalization current of the single battery to be equalized in an equalization process of the single battery to be equalized; when the equalizing current is greater than or equal to the preset equalizing current, reducing the equalizing duty ratio of the single battery to be equalized; or when the equalizing current is smaller than the preset equalizing current, increasing the equalizing duty ratio of the single battery to be equalized.

In another embodiment, the control module 84 is configured to determine, for each cell in the battery pack, an initial voltage value and an initial current value of the cell before entering the constant current condition; determining the voltage value and the current value of the single battery under the constant current working condition; and determining the internal resistance value of the single battery as the ratio of the voltage difference value to the current difference value according to the voltage difference value between the initial voltage value and the voltage value of the single battery under the constant current working condition and the current difference value between the initial current value and the current value of the single battery under the constant current working condition.

In another embodiment, the control module 84 is configured to detect whether the cell enters a constant current condition; and after the single battery enters a constant-current working condition and the constant-current working condition lasts for a preset time, determining the voltage value and the current value of the single battery under the constant-current working condition.

In another embodiment, the control module 84 is further configured to, in the balancing process of the single battery cell to be balanced, adjust the balancing duty ratio of the single battery cell to be balanced when it is detected that any one of the performance parameters of the single battery cell to be balanced satisfies a balancing duty ratio 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 another embodiment, the control module 84 is further configured to determine the single battery to be equalized from the battery pack according to a performance parameter of each single battery in the battery pack, where the performance parameter includes at least one of a voltage, an SOC, an internal resistance, a self-discharge rate, a voltage change rate, an electric quantity change rate, and a time change rate.

The present disclosure also provides a vehicle including the above battery equalization system.

The present disclosure also provides a computer readable storage medium having stored thereon computer program instructions which, when executed by a processor, implement the above battery equalization method.

The present disclosure also provides an electronic device comprising the above 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 respective technical features described in the above embodiments may be combined in any suitable manner without contradiction. The various possible combinations are not separately described in this disclosure in order to avoid unnecessary repetition.

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 the internal resistance value of each single battery 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;

determining the balancing duty ratio of the single battery to be balanced according to the internal resistance value of the single battery to be balanced in the battery pack and the reference internal resistance value, wherein the balancing duty ratio is the ratio of the duration of the balancing time period to the duration of the unit period;

2. The method according to claim 1, wherein the determining the balancing duty cycle of the single battery to be balanced according to the internal resistance value of the single battery to be balanced and the reference internal resistance value comprises:

and determining the balancing duty ratio of the single battery to be balanced according to the internal resistance difference value of the internal resistance value of the single battery to be balanced and the reference internal resistance value and the preset corresponding relation between the internal resistance difference value and the balancing duty ratio.

3. The method according to claim 1, wherein the determining the balancing duty cycle of the single battery to be balanced according to the internal resistance value of the single battery to be balanced and the reference internal resistance value comprises:

determining the single battery with the minimum difference between the internal resistance value and the reference internal resistance value in the battery pack as a reference battery;

determining a first SOC value corresponding to the reference internal resistance value according to the reference internal resistance value, the voltage value of the reference battery, the current value of the reference battery and an open-circuit voltage OCV-remaining capacity SOC curve corresponding to the reference battery;

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

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

4. The method according to claim 3, wherein the determining a first SOC value corresponding to the reference internal resistance value according to the reference internal resistance value, the voltage value of the reference battery, the current value of the reference battery, and an open-circuit voltage OCV-remaining capacity SOC curve corresponding to the reference battery comprises:

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

determining a second SOC value corresponding to the internal resistance value of the single battery to be balanced according to the internal resistance value of the single battery to be balanced, the voltage value of the single battery to be balanced, the current value of the single battery to be balanced and the OCV-SOC curve corresponding to the single battery to be balanced, and the determining method comprises the following steps:

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

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

5. The method according to claim 4, wherein the step of determining the balancing duty cycle of the single battery to be balanced according to the first SOC value and the second SOC value comprises the steps of:

according to Δ Q ═ Δ SOC × C_nDetermining 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_nThe available capacity of the single battery to be balanced is obtained;

determining the balancing duty ratio of the single battery to be balanced according to the value of tau (delta Q/I)/t, wherein t is the preset balancing duration of the single battery to be balanced, I is the preset balancing current of the single battery to be balanced, and tau is the balancing duty ratio.

6. The method of claim 5, further comprising:

in the balancing process of the single battery to be balanced, obtaining the balancing current of the single battery to be balanced;

when the equalizing current is greater than or equal to the preset equalizing current, reducing the equalizing duty ratio of the single battery to be equalized; or,

and when the equalizing current is smaller than the preset equalizing current, increasing the equalizing duty ratio of the single battery to be equalized.

7. The method of claim 1, wherein obtaining the internal resistance value of each cell in the battery pack comprises:

determining an initial voltage value and an initial current value of each single battery in the battery pack before the single battery enters a constant current working condition;

determining the voltage value and the current value of the single battery under the constant current working condition;

and determining the internal resistance value of the single battery as the ratio of the voltage difference value to the current difference value according to the voltage difference value between the initial voltage value and the voltage value of the single battery under the constant current working condition and the current difference value between the initial current value and the current value of the single battery under the constant current working condition.

8. The method of claim 7, wherein determining the voltage and current values of the cell under the constant current condition comprises:

detecting whether the single battery enters a constant current working condition or not;

and after the single battery enters a constant-current working condition and the constant-current working condition lasts for a preset time, determining the voltage value and the current value of the single battery under the constant-current working condition.

9. The method of claim 1, further comprising:

in the balancing process of the single battery to be balanced, when any performance parameter of the single battery to be balanced is detected to meet a balancing duty ratio adjusting condition corresponding to the performance parameter, adjusting the balancing duty ratio of the single battery to be balanced, wherein the performance parameter at least comprises: voltage, SOC, internal resistance, self-discharge rate, rate of change of voltage, rate of change of electrical quantity, and rate of change of time.

10. The method of claim 1, wherein the obtaining a reference internal resistance value required for equalization includes:

determining the minimum internal resistance value of the internal resistance values of the single batteries in the battery pack as the reference internal resistance value; or,

determining the maximum internal resistance value of the internal resistance values of the single batteries in the battery pack as the reference internal resistance value; or,

and determining the average value of the internal resistance values of the single batteries in the battery pack as the reference internal resistance value.

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

and determining the single batteries to be balanced from the battery pack according to the performance parameters of the single batteries in the battery pack, wherein the performance parameters comprise at least one of voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate and time change rate.

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 acquiring the internal resistance value of each single battery 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; determining a reference internal resistance value according to the internal resistance value of each single battery; determining the balancing duty ratio of the single battery to be balanced according to the internal resistance value of the single battery to be balanced in the battery pack and the reference internal resistance value, wherein the balancing duty ratio is the ratio of the duration of the balancing time period to the duration of the unit period; according to the balance duty ratio, controlling the balance of the single battery to be balanced in the balance time period of the unit cycle;

13. The system according to claim 12, wherein the control module is configured to determine the balancing duty cycle of the single battery cell to be balanced according to a difference between the internal resistance value of the single battery cell to be balanced and the reference internal resistance value, and a preset corresponding relationship between the difference and the balancing duty cycle.

14. The system of claim 12, wherein the control module is configured to determine a cell in the battery pack having a smallest difference between the internal resistance value and the reference internal resistance value as a reference cell; determining a first SOC value corresponding to the reference internal resistance value according to the reference internal resistance value, the voltage value of the reference battery, the current value of the reference battery and an open-circuit voltage OCV-remaining capacity SOC curve corresponding to the reference battery; determining a second SOC value corresponding to the internal resistance value of the single battery to be balanced according to the internal resistance value of the single battery to be balanced, the voltage value of the single battery to be balanced, the current value of the single battery to be balanced and the OCV-SOC curve corresponding to the single battery to be balanced; and determining the balance duty ratio of the single battery to be balanced according to the first SOC value and the second SOC value.

15. The system of claim 14, wherein the control module is configured to determine a reference OCV value of the reference battery according to the reference internal resistance value, the voltage value of the reference battery, and the current 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_nDetermining 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_nThe available capacity of the single battery to be balanced is obtained; determining the balancing duty ratio of the single battery to be balanced according to the value of tau (delta Q/I)/t, wherein t is the preset balancing duration of the single battery to be balanced, I is the preset balancing current of the single battery to be balanced, and tau is the balancing duty ratio.

17. The system according to claim 16, wherein the control module is further configured to obtain an equalization current of the cell to be equalized in an equalization process of the cell to be equalized; when the equalizing current is greater than or equal to the preset equalizing current, reducing the equalizing duty ratio of the single battery to be equalized; or when the equalizing current is smaller than the preset equalizing current, increasing the equalizing duty ratio of the single battery to be equalized.

18. The system of claim 12, wherein the control module is configured to determine, for each cell in the battery pack, an initial voltage value and an initial current value of the cell before the cell enters a constant current condition; determining the voltage value and the current value of the single battery under the constant current working condition; and determining the internal resistance value of the single battery as the ratio of the voltage difference value to the current difference value according to the voltage difference value between the initial voltage value and the voltage value of the single battery under the constant current working condition and the current difference value between the initial current value and the current value of the single battery under the constant current working condition.

19. The system of claim 18, wherein the control module is configured to detect whether the cell enters a constant current condition; and after the single battery enters a constant-current working condition and the constant-current working condition lasts for a preset time, determining the voltage value and the current value of the single battery under the constant-current working condition.

20. The system according to claim 12, wherein the control module is further configured to, in the balancing process of the single battery cells to be balanced, adjust the balancing duty cycle of the single battery cells to be balanced when it is detected that any one of the performance parameters of the single battery cells to be balanced satisfies a balancing duty cycle adjustment condition corresponding to the performance parameter, where the performance parameter at least includes: voltage, SOC, internal resistance, self-discharge rate, rate of change of voltage, rate of change of electrical quantity, and rate of change of time.

21. The system according to any one of claims 12-20, wherein the control module is further configured to determine the cell to be equalized from the battery pack according to a performance parameter of each cell in the battery pack, wherein the performance parameter includes at least one of a voltage, an SOC, an internal resistance, a self-discharge rate, a voltage change rate, a charge change rate, and a 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 acquisition module when it is determined that the single battery connected with the control module does not need equalization; or,

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.

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