CN110015189B

CN110015189B - Battery equalization method, system, vehicle, storage medium and electronic device

Info

Publication number: CN110015189B
Application number: CN201710776100.7A
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: 2022-05-13
Anticipated expiration: 2037-08-31
Also published as: CN110015189A

Abstract

The present disclosure relates to a battery equalization method, a system, a vehicle, a storage medium, and an electronic device, the method comprising: acquiring the electric quantity change rate of each single battery in the battery pack; determining a reference electric quantity change rate required by balance judgment according to the electric quantity change rate of each single battery in the battery pack; and determining the single batteries needing to be balanced according to the electric quantity change rate of at least one single battery and the reference electric quantity change rate. By adopting the method, the single batteries needing to be balanced are determined according to the electric quantity change rate of at least one single battery in the battery pack. The single batteries needing to be balanced are not determined according to the SOC value or the load voltage value fixedly any more, the electric quantity change rate of the single batteries is used as battery information according to which the single batteries needing to be balanced are determined, the battery information according to which the single batteries needing to be balanced are determined is enriched, and a diversified method for determining the single batteries needing to be balanced is provided.

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 balancing method, a battery balancing 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 generally comprises a module formed by connecting a plurality of single batteries in series. With the use of batteries, the difference between the single batteries is gradually enlarged, the consistency between the single batteries is poor, the capacity of the battery pack is limited due to the short plate effect of the batteries, 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 very important significance for effectively and uniformly managing the power batteries of the electric automobile, being beneficial to improving the consistency of the batteries in the battery pack, reducing the capacity loss of the batteries, and prolonging the service life of the batteries and the driving range of the electric automobile.

At present, balancing 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 acquired in real time, and then a single battery needing to be balanced is determined according to the battery information (such as an SOC value and a load voltage value), and further the single battery needing to be balanced is balanced. Therefore, the battery information for determining the single batteries needing to be balanced is single.

Disclosure of Invention

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

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

acquiring the electric quantity change rate of each single battery in the battery pack;

determining a reference electric quantity change rate required by balance judgment according to the electric quantity change rate of each single battery in the battery pack;

and determining the single batteries needing to be balanced according to the electric quantity change rate of at least one single battery and the reference electric quantity change rate.

Optionally, the determining the single battery needing to be balanced according to the electric quantity change rate of the at least one single battery and the reference electric quantity change rate includes:

determining a power change rate difference between the power change rate of the at least one cell and the reference power change rate;

acquiring a balance starting threshold;

and determining the single battery with the electric quantity change rate difference larger than or equal to the balance starting threshold value in the at least one single battery as the single battery needing to be balanced.

Optionally, the determining a reference electric quantity change rate required by the equalization judgment according to the electric quantity change rate of each single battery in the battery pack includes:

determining the minimum value of the electric quantity change rates of all the single batteries in the battery pack as the reference electric quantity change rate;

the determining a power change rate difference between the power change rate of the at least one battery cell and the reference power change rate includes:

determining a capacity change rate difference between the following battery cell capacity change rates and the reference capacity change rate:

the single battery with the largest electric quantity change rate in the battery pack; or

And a cell other than the cell whose rate of change in electric quantity is the minimum value in the battery pack.

Optionally, after determining the single battery with the power change rate difference value greater than or equal to the balancing start threshold value in the at least one single battery as the single battery needing balancing, the method further includes:

when the battery pack is in a charging process, controlling the single battery with the electric quantity change rate difference value larger than or equal to the equalization starting threshold value in the at least one single battery to charge;

and when the battery pack is in the discharging process, controlling the discharging of the single battery of which the electric quantity change rate difference is greater than or equal to the balance starting threshold value in the at least one single battery.

determining the maximum value of the electric quantity change rates of all the single batteries in the battery pack as the reference electric quantity change rate;

the single battery with the minimum electric quantity change rate in the battery pack; or

And a cell other than the cell having the maximum value of the rate of change in electric quantity in the battery pack.

when the battery pack is in a charging process, controlling the single battery with the electric quantity change rate difference value larger than or equal to the equalization starting threshold value in the at least one single battery to discharge;

and when the battery pack is in the discharging process, controlling the single battery with the electric quantity change rate difference value larger than or equal to the equalizing starting threshold value in the at least one single battery to charge.

determining the average value of the electric quantity change rates of all the single batteries in the battery pack as the reference electric quantity change rate;

the determining a power change rate difference between the power change rate of the at least one cell and the reference power change rate includes:

and determining the electric quantity change rate difference value between the electric quantity change rate of each single battery in the battery pack and the reference electric quantity change rate.

when the battery pack is in a charging process, controlling the single batteries with the electric quantity change rate smaller than the average value in the single batteries to be balanced to discharge, and controlling the single batteries with the electric quantity change rate larger than the average value in the single batteries to be balanced to charge;

and when the battery pack is in a discharging process, controlling the single batteries of which the electric quantity change rates are smaller than the average value in the single batteries to be balanced to charge, and controlling the single batteries of which the electric quantity change rates are larger than the average value in the single batteries to be balanced to discharge.

Optionally, after the determining the single battery needing equalization according to the power change rate of the at least one single battery and the reference power change rate, the method further includes:

determining the target equalization duration of the single battery needing equalization according to the electric quantity change rate of the single battery needing equalization and the reference electric quantity change rate;

and controlling the balancing of the single battery needing balancing according to the target balancing duration of the single battery needing balancing.

Optionally, the acquiring the power change rate of each single battery in the battery pack includes:

and in the process of charging or discharging each single battery in the battery pack, determining the electric quantity required to be charged or discharged when the load voltage value of each single battery in the battery pack changes by the unit value.

A second aspect of the present disclosure provides a battery equalization system, including: a balancing module, an acquisition module and a control module,

the acquisition module is used for acquiring the electric quantity change rate of each single battery in the battery pack;

the control module is used for determining a reference electric quantity change rate required by balance judgment according to the electric quantity change rate of each single battery in the battery pack, and determining the single batteries required to be balanced according to the electric quantity change rate of at least one single battery and the reference electric quantity change rate;

the balancing module is used for balancing the single batteries needing balancing.

Optionally, the control module is configured to:

acquiring a balance starting threshold;

Optionally, the control module is configured to:

determining the minimum value of the electric quantity change rates of all the single batteries in the battery pack as the reference electric quantity change rate; or

Determining the maximum value of the electric quantity change rates of all the single batteries in the battery pack as the reference electric quantity change rate; or

And determining the average value of the electric quantity change rates of all the single batteries in the battery pack as the reference electric quantity change rate.

Optionally, the control module is configured to:

the equalization module is configured to:

and balancing the single batteries needing to be balanced according to the target balancing duration of the single batteries needing to be balanced.

Optionally, the control module is configured to:

Optionally, 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 it is determined that the single battery connected with the control module does not need equalization; or,

the control module is further used for controlling the control module to be connected with the corresponding sampling module at a first time and to be connected with the corresponding balancing module at a second time when the fact that the single battery connected with the control module needs to be balanced is determined.

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

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

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

A third aspect of the present disclosure provides a computer readable storage medium having stored thereon computer program instructions which, when executed by a processor, implement the method of the first aspect of the present disclosure.

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

a computer-readable storage medium according to a third aspect of the disclosure; and

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

A fifth aspect of the present disclosure provides a vehicle including: a battery pack and a battery equalization system according to a fourth aspect of the present disclosure.

Through the technical scheme, the single batteries needing to be balanced are determined according to the electric quantity change rate of at least one single battery in the battery pack. The single batteries needing to be balanced are not determined according to the SOC value or the load voltage value fixedly any more, the electric quantity change rate of the single batteries is used as battery information according to which the single batteries needing to be balanced are determined, the battery information according to which the single batteries needing to be balanced are determined is enriched, and a diversified method for determining the single batteries needing to be balanced is provided.

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 voltage difference between a single battery to be equalized and a reference battery according to an embodiment of the disclosure;

fig. 7 is a schematic voltage difference diagram of a cell to be equalized and a reference cell according to another embodiment of the disclosure;

fig. 8 is an open circuit voltage OCV-remaining capacity SOC curve of a unit cell according to an embodiment of the present disclosure;

FIG. 9 is a schematic diagram of a battery internal resistance model of an embodiment of the present disclosure;

fig. 10 is a schematic diagram of an equalization module according to an embodiment of the present disclosure.

Detailed Description

The following detailed description of the embodiments of the disclosure refers to 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 the N acquisition modules and the N equalization modules through 2 × N control channels, respectively.

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.

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 connections may be connections that alternate according to a certain periodicity. 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 cell via a control channel 305. The control module is used for controlling the connection of the control module and the corresponding sampling module when the single battery connected with the control module is determined not to need balancing; 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, electric quantity change rate, and the like of the single battery.

The control module 301 determines the single battery to be balanced, which needs to be balanced, according to the battery information of the single battery acquired by the acquisition module 302. For the single battery to be equalized which needs to be started, the control module 301 controls the equalization module corresponding to the single battery to be equalized, and equalizes the single battery to be equalized in an equalization 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.

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 N acquisition modules and the N equalization modules through the N control channels, respectively.

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. 4, an exemplary schematic diagram of two single batteries 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.

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, acquiring the rate of change of the electric quantity of each battery cell in the battery pack;

in step S52, determining a reference power change rate required for equalization determination according to the power change rate of each single battery in the battery pack;

in step S53, a cell requiring equalization is determined according to the power change rate of at least one cell and the reference power change rate.

The electric quantity change rate of the single battery can be the electric quantity change amount when the unit of the specified physical quantity of the single battery is changed. For example, the present disclosure will be described by taking as an example the amount of electricity charged necessary for the voltage of the unit cell to rise by one unit voltage from the initial voltage, or the amount of electricity decreased by the voltage of the unit cell to fall by one unit voltage from the initial voltage.

In one embodiment, the step S51 is not limited to the following embodiments:

Acquiring the charged electric quantity required by the voltage of each single battery to rise by one unit voltage (for example, 1V) from the initial terminal voltage in the charging process of the battery pack;

for each single battery in the battery pack, determining the electric quantity change rate of the single battery as the ratio of the value of the electric quantity required to be charged of the single battery to the value of the unit voltage; or,

acquiring the reduced electric quantity of the voltage of each single battery, which is reduced by one unit voltage from the initial terminal voltage in the discharging process of the battery pack;

and for each single battery in the battery pack, determining the electric quantity change rate of the single battery as the ratio of the reduced electric quantity value of the single battery to the unit voltage value.

In the charging or discharging process of the battery pack, the voltage and electric quantity change conditions of the single batteries are recorded, so that the electric quantity change rate of the single batteries can be obtained according to the voltage and electric quantity change conditions and the method.

Since the rate of change of the voltage of the battery with the capacity is different in different SOC states. Therefore, the SOC state difference of each single battery can be identified according to the difference of the electric quantity change rate of the battery, the consistency difference of each single battery is further identified, and the single batteries needing to be balanced are further determined.

In step S52, a reference rate of change in electric quantity is determined based on the rate of change in electric quantity of each unit cell.

In one embodiment, the charge change rate of any single cell in the battery pack may be used as the reference charge change rate, for example, the charge change rate of the 2 nd single cell in the battery pack may be used as the reference charge change rate, or the charge change rate of the single cell with the largest charge change rate in the battery pack may be used as the reference charge change rate, or the charge change rate of the single cell with the smallest charge change rate in the battery pack may be used as the reference charge change rate, or the charge change rate of the single cell with the middle charge change rate in the battery pack (for the case where the battery pack includes an odd number of single cells).

In another embodiment, the reference capacity change rate may also be calculated according to the capacity change rate of each single battery in the battery pack, for example: the average value of the charge change rates of the respective unit cells in the battery pack, or the average value of the charge change rates of the two unit cells in the battery pack with the charge change rates arranged at the middle (for the case where the battery pack includes an even number of unit cells).

Optionally, step S53 includes:

acquiring a balance starting threshold;

The equalization starting threshold is a threshold used for determining whether equalization is started for any single battery in the battery pack, that is, a threshold used for judging whether any single battery in the battery pack is a single battery needing equalization.

Firstly, at least one single battery is selected from a battery pack, and then the electric quantity change rate of the selected at least one single battery is differed from the reference electric quantity change rate to obtain an electric quantity change rate difference value of the selected at least one single battery. Then comparing the obtained electric quantity change rate difference value with an equalization opening threshold value, and if the electric quantity change rate difference value of one single battery is larger than or equal to the equalization opening threshold value, determining that the battery is the single battery needing equalization; and if the electric quantity change rate difference value of one single battery is smaller than the equalization starting threshold value, the battery is a single battery which does not need equalization.

And when the reference electric quantity change rate is different, the selected at least one single battery is different, and the process of balancing the single battery needing to be balanced is different. Hereinafter, the reference electricity-quantity change rate will be described as the minimum value, the maximum value, and the average value among the electricity-quantity change rates of the individual cells in the battery pack.

1) In a case that the reference electric quantity change rate is the minimum value among the electric quantity change rates of the individual batteries in the battery pack, the determining an electric quantity change rate difference value between the electric quantity change rate of the at least one individual battery and the reference electric quantity change rate required for the equalization judgment includes: determining an electric quantity change rate difference value between the electric quantity change rate of the following single batteries and a reference electric quantity change rate required by balance judgment:

Correspondingly, after determining that the single battery needing to be balanced is the single battery with the power change rate difference value of the at least one single battery being greater than or equal to the balancing start threshold, the method further includes: when the battery pack is in a charging process, controlling the single battery with the electric quantity change rate difference value larger than or equal to the equalization starting threshold value in the at least one single battery to charge; and when the battery pack is in the discharging process, controlling the discharging of the single battery of which the electric quantity change rate difference is greater than or equal to the balance starting threshold value in the at least one single battery.

Specifically, when the reference electric quantity change rate is the minimum value among the electric quantity change rates of the individual batteries in the battery pack, only the electric quantity change rate of the individual battery with the largest electric quantity change rate in the battery pack may be subtracted from the reference electric quantity change rate, so as to determine whether the individual battery with the largest electric quantity change rate in the battery pack is the individual battery requiring equalization. This embodiment can only determine if one cell needs to be balanced.

Under the condition that the reference electric quantity change rate is the minimum value of the electric quantity change rates of the single batteries in the battery pack, the difference between the electric quantity change rates of the other single batteries except the single battery with the minimum electric quantity change rate in the battery pack and the reference electric quantity change rate can be made, and whether the other single batteries except the single battery with the minimum electric quantity change rate in the battery pack are the single batteries needing to be balanced or not can be further judged. This embodiment is a batch determination method, and can determine whether or not the other cells in the battery pack, except the cell with the smallest rate of change of the electric quantity, are the cells that need to be balanced at one time.

Under the condition that the reference electric quantity change rate is the minimum value of the electric quantity change rates of the single batteries in the battery pack, the process of balancing the single batteries needing to be balanced is as follows:

considering that the rate of change of the amount of electricity is large, on the one hand, it may be caused by small internal resistance of the battery. Another aspect may be due to the presence of a capacity difference, i.e., an initial difference in SOC. The battery with small internal resistance is not seriously aged, and the voltage of the battery rises slowly in the charging process, so that the battery pack discharges the single batteries needing to be balanced when in the charging process; considering that the battery with small internal resistance is not seriously aged, the voltage of the battery is slowly reduced in the discharging process, and therefore, when the battery pack is in the discharging process, the single batteries needing to be balanced are charged.

2) In a case that the reference electric quantity change rate is a maximum value among electric quantity change rates of the individual batteries in the battery pack, the determining an electric quantity change rate difference between the electric quantity change rate of the at least one individual battery and the reference electric quantity change rate required for the equalization judgment includes: determining an electric quantity change rate difference value between the electric quantity change rate of the following single batteries and a reference electric quantity change rate required by balance judgment:

Specifically, when the reference electric quantity change rate is the maximum value among the electric quantity change rates of the individual batteries in the battery pack, only the electric quantity change rate of the individual battery with the smallest electric quantity change rate in the battery pack may be subtracted from the reference electric quantity change rate, so as to determine whether the individual battery with the smallest electric quantity change rate in the battery pack is the individual battery requiring equalization. This embodiment can only determine if one cell needs to be balanced.

Under the condition that the reference electric quantity change rate is the maximum value of the electric quantity change rates of the single batteries in the battery pack, the difference between the electric quantity change rates of the other single batteries except the single battery with the maximum electric quantity change rate in the battery pack and the reference electric quantity change rate can be made, and whether the other single batteries except the single battery with the maximum electric quantity change rate in the battery pack are the single batteries needing to be balanced or not can be further judged. This embodiment is a batch determination method, and can determine whether or not the other cells in the battery pack, except the cell with the largest rate of change of the electric quantity, are the cells that need to be balanced at one time.

Under the condition that the reference electric quantity change rate is the maximum value of the electric quantity change rates of the single batteries in the battery pack, the process of balancing the single batteries needing to be balanced is as follows:

3) In a case that the reference electric power change rate is an average value of electric power change rates of the individual batteries in the battery pack, determining an electric power change rate difference between the electric power change rate of the at least one individual battery and a reference electric power change rate required for the equalization determination includes: and determining the electric quantity change rate difference value between the electric quantity change rate of each single battery in the battery pack and the reference electric quantity change rate.

Correspondingly, after determining that the single battery needing to be balanced is the single battery with the power change rate difference value of the at least one single battery being greater than or equal to the balancing start threshold, the method further includes:

Specifically, when the reference electric quantity change rate is an average value of the electric quantity change rates of the individual batteries in the battery pack, the difference between the electric quantity change rate of each individual battery in the battery pack and the reference electric quantity change rate can be made, and whether each individual battery in the battery pack is an individual battery that needs to be balanced or not can be further determined. The embodiment is a batch judgment mode, and can judge whether each single battery in the battery pack is a single battery needing to be balanced at one time.

Under the condition that the reference electric quantity change rate is the average value of the electric quantity change rates of all the single batteries in the battery pack, the process of balancing the single batteries needing to be balanced is as follows:

considering that the rate of change of the amount of electricity is large, on the one hand, it may be caused by small internal resistance of the battery. Another aspect may be due to the presence of a capacity difference, i.e., an initial difference in SOC. The battery with small internal resistance is not seriously aged, the voltage of the battery rises slowly in the charging process, and the voltage of the battery drops slowly in the discharging process, so that when the battery pack is in the charging process, the battery pack discharges the single battery with the electric quantity change rate smaller than the average value of the electric quantity change rates in the single batteries to be balanced, and charges the single battery with the electric quantity change rate larger than the average value of the electric quantity change rates in the single batteries to be balanced; similarly, when the battery pack is in the discharging process, the single batteries with the electric quantity change rate smaller than the average value of the electric quantity change rates in the single batteries needing to be balanced are charged, and the single batteries with the electric quantity change rates larger than the average value of the electric quantity change rates in the single batteries needing to be balanced are discharged.

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

and controlling the balancing of the single batteries needing balancing according to the target balancing duration of the single batteries needing balancing.

After the single batteries needing to be balanced are determined, the target balancing time length of the single batteries needing to be balanced can be determined, and then the single batteries needing to be balanced are balanced according to the determined target balancing time length. The target equalization duration is determined according to the electric quantity change rate of the single batteries needing equalization and the reference electric quantity change rate.

Optionally, determining a target equalization duration of the single battery to be equalized according to the electric quantity change rate of the single battery to be equalized and the reference electric quantity change rate, including:

determining the single battery with the minimum difference between the electric quantity change rate and the reference electric quantity change rate in the battery pack as a reference battery;

when the initial end voltage of the single battery to be balanced is different from the initial end voltage of the reference battery, determining the target balancing time length according to the initial end voltage of the single battery to be balanced and the initial end voltage of the reference battery;

when the initial end voltage of the single battery to be equalized is the same as the initial end voltage of the reference battery, determining the target equalization time length according to the electric quantity required to be charged when the voltage of the single battery to be equalized rises from the initial end voltage by one unit voltage and the electric quantity required to be charged when the voltage of the reference battery rises from the initial end voltage by one unit voltage, or determining the target equalization time length according to the electric quantity reduced when the voltage of the single battery to be equalized falls from the initial end voltage by one unit voltage and the electric quantity reduced when the voltage of the reference battery falls from the initial end voltage by one unit voltage.

Determining the target equalization duration according to the initial terminal voltage of the single battery to be equalized and the initial terminal voltage of the reference battery, wherein the determining the target equalization duration comprises the following steps:

determining a first SOC value corresponding to the initial terminal voltage value of the reference battery according to the initial terminal voltage value of the reference battery and an open-circuit voltage OCV-remaining capacity SOC curve of the reference battery;

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

and determining the target equalization time length according to the first SOC value and the second SOC value.

Similarly, determining the target equalization duration according to the electric quantity charged by the voltage of the single battery to be equalized after increasing by one unit voltage from the initial terminal voltage and the electric quantity charged by the voltage of the reference battery after increasing by one unit voltage from the initial terminal voltage, includes:

determining the capacity difference between the battery to be equalized and the reference battery according to the electric quantity required to be charged when the voltage of the single battery to be equalized rises from the initial end voltage by one unit voltage and the electric quantity required to be charged when the voltage of the reference battery rises from the initial end voltage by one unit voltage; and determining the target balancing duration according to the capacity difference and the balancing current of the single battery to be balanced.

Similarly, determining the target equalization duration according to the electric quantity reduced by the voltage of the single battery to be equalized dropping by one unit voltage from the initial terminal voltage and the electric quantity reduced by the voltage of the reference battery dropping by one unit voltage from the initial terminal voltage includes:

determining the capacity difference between the single battery to be equalized and the reference battery according to the electric quantity reduced by the voltage of the single battery to be equalized after dropping one unit voltage from the initial end voltage and the electric quantity reduced by the voltage of the reference battery after dropping one unit voltage from the initial end voltage; and determining the target balancing duration according to the capacity difference and the balancing current of the single battery to be balanced.

In the embodiment of the present disclosure, the initial terminal voltage is a voltage detected when the battery pack starts charging or discharging, or a voltage of the unit battery detected at a certain set detection timing.

Referring to fig. 6, fig. 6 shows a case where the initial terminal voltage of the unit cell to be equalized and the initial terminal voltage of the reference cell are different. Referring to fig. 7, fig. 7 shows a case where there is no difference between the initial terminal voltage of the unit cell to be equalized and the initial terminal voltage of the reference cell, in which case the rate of change of the charge amount of the unit cell is mainly caused by the difference in the voltage change rate during the charging or discharging process.

For the case shown in fig. 6, the single batteries are in different SOC intervals, the same voltage is changed, and the amount of electricity required to be charged or discharged is different. Therefore, the electric quantity difference of the two single batteries can be determined according to the initial end voltages of the two single batteries, and the target equalization duration of the single battery to be equalized is further determined according to the electric quantity difference of the two single batteries.

Specifically, a reference OCV value of the reference battery is determined according to an initial terminal 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;

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

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;

according to Δ Q ═ΔSOC×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;

and determining the target equalization duration according to the t ═ delta Q/I, wherein t is the target equalization duration, and I is the equalization current of the single battery to be equalized.

For the case shown in fig. 7, the capacity difference between the cell to be equalized and the reference cell may be determined according to the amount of electric charge required to be charged by the voltage of the cell to be equalized rising by one unit voltage from the initial terminal voltage and the amount of electric charge required to be charged by the voltage of the reference cell rising by one unit voltage from the initial terminal voltage; or determining the capacity difference between the single battery to be equalized and the reference battery according to the electric quantity reduced by the voltage of the single battery to be equalized after dropping one unit voltage from the initial end voltage and the electric quantity reduced by the voltage of the reference battery after dropping one unit voltage from the initial end voltage;

and determining the target equalization time length according to the t ═ delta Q/I, wherein delta Q is the capacity difference, t is the target equalization time length, and I is the equalization current of the single battery to be equalized.

In one embodiment of the present disclosure, the OCV-SOC curve is obtained through measurement. For example, for a certain single battery, in the process of changing the SOC value from 0 to 100%, the open circuit voltage OCV of the primary battery 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 the SOC-OCV curve of the single battery. Fig. 8 is a schematic diagram of an OCV-SOC curve of a unit cell. The OCV is an Open Circuit Voltage (Open Circuit Voltage), and the SOC is a remaining battery capacity (State of Charge).

The OCV value is an open circuit voltage value of the unit cell, and is different from a load voltage value. Referring to fig. 9 and equation (1), when the battery pack is in a discharging state or a charging state, the single battery is equivalent to an ideal voltage source and is connected in series with a resistor R by using a battery 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 an open circuit voltage value:

OCV＝V_L+I×R (1)

wherein, V_LThe 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.

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).

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

Alternatively, in another embodiment, the voltage acquired at the moment when the battery to be referenced stops operating and reaches a steady state, or the battery just starts operating is itself an open circuit voltage or can be approximately regarded as an open circuit voltage, so the OCV value of the reference battery can be directly acquired in this case.

Therefore, the first SOC value and the second SOC value 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.

After obtaining the first SOC-value and the second SOC-value, performing 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 the difference in SOC between a first SOC value and a second SOC value, C_nThe available capacity of the single battery to be balanced;

and determining a target equalization time length according to the t ═ delta Q/I, wherein t is the target equalization time length, and I is the equalization current of the single battery to be equalized.

It should be understood that if it is determined that there is no single battery needing to be balanced, whether there is a single battery needing to be balanced is continuously judged according to the electric quantity change rate of at least one single battery in the battery pack. When it is determined that no single battery needs to be balanced, the control module does not act, so that the balancing module corresponding to any battery is not started.

Referring to fig. 10, a schematic diagram of an equalization module according to an embodiment of the disclosure is shown. And controlling the single batteries to be balanced, wherein the balancing judgment needs to be combined. According to the step of equalization judgment, whether the equalization mode of the single battery to be equalized is passive equalization (namely, the single battery to be equalized is discharged) or active equalization (namely, the single battery to be equalized is charged) is determined, and the corresponding equalization module is conducted.

Referring to fig. 10, 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 to be balanced which needs to be passively balanced, the control module controls the conduction of a parallel loop between the single battery to be balanced and the corresponding resistor of the single battery to be balanced so as to execute the passive balancing of the single battery. Referring to fig. 10, 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 to be equalized 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. 10, 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 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 transmitted to the single battery to be balanced, and the electricity of the single battery to be balanced is increased.

Referring to fig. 10, when the generator 92 is an alternator, the balancing module further comprises a rectifier 93 connected in series with the generator 92, each charging branch 130 being connected in series with said rectifier 132. 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. 10, 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. 10, 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. 10, 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.

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, and the balancing module performs balancing respectively.

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.

Claims

1. A method of balancing a battery, comprising:

2. The method according to claim 1, wherein the determining the single battery needing equalization according to the power change rate of the at least one single battery and the reference power change rate comprises:

acquiring a balance starting threshold;

3. The method according to claim 2, wherein the determining a reference power change rate required for equalization judgment according to the power change rate of each single battery in the battery pack comprises:

4. The method according to claim 3, wherein after determining the cell with the charge change rate difference value greater than or equal to the balancing start threshold value in the at least one cell as the cell requiring balancing, the method further comprises:

5. The method according to claim 2, wherein the determining a reference power change rate required for equalization judgment according to the power change rate of each single battery in the battery pack comprises:

6. The method according to claim 5, wherein after determining the cell with the charge change rate difference value greater than or equal to the balancing start threshold value in the at least one cell as the cell requiring balancing, the method further comprises:

when the battery pack is in a charging process, controlling the single batteries of which the electric quantity change rate difference is greater than or equal to the equalization starting threshold value to discharge;

7. The method according to claim 2, wherein the determining a reference power change rate required for equalization judgment according to the power change rate of each single battery in the battery pack comprises:

8. The method according to claim 7, wherein after determining the cell whose charge change rate difference is greater than or equal to the balancing start threshold value in the at least one cell as the cell requiring balancing, the method further comprises:

9. The method according to claim 1, wherein after determining the cell requiring equalization according to the charge change rate of the at least one cell and the reference charge change rate, the method further comprises:

10. The method of claim 1, wherein the obtaining the rate of change of the charge of each cell in the battery pack comprises:

and in the process of charging or discharging each single battery in the battery pack, determining the electric quantity required to be charged or discharged when the load voltage value of each single battery in the battery pack changes by a unit value.

11. A battery equalization system, comprising: a balancing module, an acquisition module and a control module,

the control module is used for determining a reference electric quantity change rate required by equilibrium judgment according to the electric quantity change rate of each single battery in the battery pack, and determining the single batteries required to be equilibrated according to the electric quantity change rate of at least one single battery and the reference electric quantity change rate;

12. The battery equalization system of claim 11, wherein the control module is configured to:

acquiring a balance starting threshold;

13. The battery equalization system of claim 11, wherein the control module is configured to:

14. The battery equalization system of claim 11, wherein the control module is configured to:

the equalization module is configured to:

15. The battery equalization system of claim 11, wherein the control module is configured to:

16. The battery equalization system of claim 11, wherein the control module is connected with the acquisition module and the equalization module corresponding to the same cell 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 cell connected with the control module does not need equalization; or,

17. The battery equalization system of claim 16, wherein the control module comprises a control chip, and the control chip is connected to the acquisition module and the equalization module corresponding to the same cell through one pin and the one channel.

18. The battery equalization system of claim 11, wherein the control module is connected to the acquisition module and the equalization module corresponding to the same cell through two channels.

19. The battery equalization system of claim 18, 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.

20. 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 1-10.

21. An electronic device, comprising:

the computer-readable storage medium recited in claim 20; and

22. A vehicle, characterized in that the vehicle comprises: a battery pack and a battery equalization system as claimed in any of claims 11-19.