CN109435774B

CN109435774B - Battery equalization method, system, vehicle, storage medium and electronic device

Info

Publication number: CN109435774B
Application number: CN201710775054.9A
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: 2022-03-18
Anticipated expiration: 2037-08-31
Also published as: CN109435774A

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 a voltage change rate value of each single battery according to battery information of each single battery of the battery pack acquired in a sampling period of a unit cycle, wherein the unit cycle comprises the sampling period and a balancing period; determining a reference voltage change rate value according to the voltage change rate value of each single battery; determining the balancing duty ratio of the single battery to be balanced according to the voltage change rate value and the reference voltage change rate value of the single battery to be balanced in the battery pack, wherein the balancing duty ratio is the ratio of the duration of a balancing period to the duration of a unit period; and controlling the balance of the single batteries to be balanced in the balancing time period of the unit cycle according to the balancing duty ratio. According to the method and the device, the battery information acquisition and the equalization are carried out in a time-sharing mode, so that the acquired battery information is more accurate, and the equalization effect is better; and the equalization is carried out according to the equalization duty ratio during equalization, so that the 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 control technologies, and in particular, to a battery equalization method, a battery equalization system, a vehicle, a storage medium, and an electronic device.

Background

A large-capacity battery that provides power energy for an electric vehicle is often referred to as a power battery. The vehicle power battery is generally formed by connecting a plurality of single batteries in series to form a module. With the use of batteries, the difference between the single batteries is gradually enlarged, the consistency between the single batteries is poor, 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 the advantages of effectively and uniformly managing the power batteries of the electric automobile, being beneficial to improving the consistency of the batteries in the power battery pack, reducing the capacity loss of the batteries, prolonging the service life of the batteries and the driving range of the electric automobile, and having very important significance.

At present, 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 acquired 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.

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

acquiring a voltage change rate value of each single battery according to battery information of each single battery of a battery pack acquired in a sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and an equalization time period;

determining a reference voltage change rate value according to the voltage change rate value of each single battery;

determining the balancing duty ratio of the single battery to be balanced according to the voltage change rate value of the single battery to be balanced in the battery pack and the reference voltage change rate 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.

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

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

the control module is used for acquiring a voltage change rate value of each single battery according to battery information of each single battery of the battery pack, which is acquired in a sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and a balancing time period; determining a reference voltage change rate value according to the voltage change rate value of each single battery; determining the balancing duty ratio of the single battery to be balanced according to the voltage change rate value of the single battery to be balanced in the battery pack and the reference voltage change rate 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.

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

In a fourth aspect, 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 described above.

In a fifth aspect, the present disclosure provides an electronic device comprising:

the computer-readable storage medium of the fourth aspect; 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 time length of the acquisition time period and the time length of the balance time period are controlled according to the balance duty ratio under the condition of unit cycle setting, so that the balance efficiency is improved, and the balance cost is 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 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 illustrating a determination process of an equalization duty ratio of a single battery to be equalized according to an embodiment of the present disclosure;

fig. 7 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. 8 is a schematic voltage difference diagram of a cell to be equalized and a reference cell according to another embodiment of the disclosure;

fig. 9 is a schematic flowchart illustrating a process of determining an equalization duty ratio of a single battery to be equalized according to a voltage value and a reference voltage value of the single battery to be equalized according to an embodiment of the present disclosure;

fig. 10 is an open circuit voltage OCV-remaining capacity SOC curve of a unit cell according to an embodiment of the present disclosure;

FIG. 11 is a schematic diagram of a battery internal resistance model according to an embodiment of the disclosure;

fig. 12 is a schematic flowchart illustrating a process of determining an equalization duty ratio of a single battery to be equalized according to a voltage value of the single battery to be equalized and a reference voltage value according to another embodiment of the present disclosure;

fig. 13 is a schematic diagram illustrating a determining process of a single battery to be equalized according to an embodiment of the disclosure; fig. 14 is a schematic flow chart illustrating the process of determining the single battery to be equalized according to the voltage in an embodiment of the present disclosure;

FIG. 15 is a schematic diagram of an equalization module of an embodiment of the present disclosure;

FIG. 16 is a flow diagram of an equalization process according to an embodiment of the present disclosure;

fig. 17 is a schematic flow chart of acquisition of an equalization duration according to an embodiment of the present disclosure;

fig. 18 is a schematic diagram illustrating adjustment of an equalization duty cycle according to an embodiment of the present disclosure.

Detailed Description

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

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

In one embodiment, each cell corresponds to one acquisition module 102 and one equalization module 103. The acquisition module 102 and the equalization module 103 corresponding to the same single battery are respectively connected with the control module 101 through different control channels. The control module can comprise a control chip, the control chip is respectively connected with the acquisition module and the balance module corresponding to the same single battery through two pins, and the two pins correspond to the two channels one by one.

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

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

In other embodiments, different 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 connection may be a connection that alternates according to a certain period. For example, referring to fig. 2, when the parallel switch 150 on the parallel branch 15 corresponding to one of the two single batteries 111 is closed for 2s under the control of the control module 14, the parallel switch 150 on the parallel branch 15 corresponding to the other of the two single batteries 111 is opened for 2s under the control of the control module 14. That is, the parallel switch 150 on the parallel branch 15 corresponding to each of the two single batteries 111 is switched from the closed state to the open state or from the open state to the closed state every two seconds in the equalization period. Therefore, on the basis of time-sharing conduction of the acquisition module and the equalization module, the single batteries sharing the same equalization module are alternately connected with the shared equalization module during the equalization time period, and equalization is realized.

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

This battery equalizing system includes: a control module 301, an acquisition module 302, an equalization module 303, and a battery pack 304. The battery pack 304 includes a plurality of unit cells connected in series. The control module 301 is connected to the acquisition module 302 and the equalization module 303 corresponding to the same 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, self-discharge 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.

From this, through with the 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 the equilibrium, unbalanced effect during the sampling, thereby balanced electric current can not influence battery voltage, thereby precision when having improved battery voltage sampling.

In one embodiment, referring to fig. 3, each cell of the battery is connected to an acquisition module 302 and an equalization module 303, respectively. If the battery pack includes N single batteries, the number of the acquisition modules 302 is N, and the number of the equalization modules 303 is N, so that the control module 301 is connected to the acquisition modules and the equalization modules through N control channels.

In the embodiment of the disclosure, the acquisition module and the equalization module corresponding to the same single battery share one control channel of the control module, so that the number of channels of the required control module is reduced, and the requirement on the number of channels of the control module chip is further reduced.

For example, in the embodiment shown in fig. 1, when the acquisition module and the balancing module are respectively connected to the control module through one control channel, 2N control channels correspond to the N single batteries. In the embodiment, the acquisition module and the equalization module of the same single battery share one control channel to be connected with the control module, and the N single batteries correspond to the N control channels, so that the number of the control channels can be reduced, and the cost of the control module is reduced.

In the embodiment shown in fig. 1, when the acquisition module and the equalization module are respectively connected to the control module through one control channel, the N unit cells correspond to the 2N control channels, and the 2N control channels need to be controlled. The acquisition module and the equalization module of the same single battery share one control channel of the control module, so that the N single batteries correspond to the N control channels, and only the N control channels need to be controlled, so that the control flow can be simplified, and the misoperation rate of the control module is reduced.

In the embodiment shown in fig. 1, when the acquisition module and the equalization module are respectively connected to the control module through one control channel, the N unit cells correspond to the 2N control channels, and the qualification rate of the control module connected through the control channels is determined by the qualification rate of the 2N control channels. In this embodiment, the acquisition module and the equalization module of the same single battery share one control channel of the control module, the N single batteries correspond to the N control channels, and the qualification rate of the control module connected through the control channels is determined by the qualification rate of the N control channels, so that the total qualification rate of the plurality of single batteries connected through the control channels to the control module in the whole system can be improved, and the qualification rate of the battery equalization system is further improved.

In an embodiment of the present disclosure, a battery equalization system includes: a Battery Management Controller (BMC) and a plurality of Battery Information Collectors (BIC). In one embodiment, the control module is disposed in the battery information collector BIC.

In another embodiment, the control module includes a first control unit disposed in the battery information collector, and a second control unit disposed in the battery management controller. The acquisition module sends acquired parameter information of the single batteries in the battery pack to the second control unit through the first control unit; the acquisition module and the balance module of the same single battery correspond to one connecting channel of the first control unit.

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

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

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

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

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

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

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

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

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

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

In the embodiment of the disclosure, the unit cycle is divided into the acquisition time period and the equalization time period, and the ratio of the duration of the equalization time period to the duration of the unit cycle is the equalization duty ratio. The battery information acquisition and the equalization are carried out in a time-sharing mode, so that the influence of the equalization current on the accuracy of the battery information acquisition is avoided when the battery information acquisition and the equalization are carried out simultaneously. 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.

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, a voltage change rate value of each cell is acquired from battery information of each cell of the battery pack acquired in a sampling period of a unit cycle, the unit cycle including the sampling period and an equalization period.

In the embodiment of the disclosure, initially, for example, when the battery pack just starts to charge or discharge, and when the battery pack is collected for the first time, the time length of the collection period and the time length of the equalization period in a unit cycle may be determined according to the initial equalization duty ratio or the equalization duty ratio of each single battery when the battery pack stops working last time, and the battery information of each single battery is collected in the collection period. In one embodiment, the initial equalization duty cycle may be set to 0, i.e., acquisition only.

After the balancing duty ratio of the single battery to be balanced is determined according to a subsequent method, the time length of the acquisition time period and the time length of the balancing time period of the unit cycle of the single battery to be balanced are determined according to the newly determined balancing duty ratio. For the single battery which does not need to be balanced, the time length of the acquisition time period and the time length of the balancing time period of the unit cycle can be determined according to the balancing duty ratio determined in the last balancing of the single battery or the preset balancing duty ratio, the battery information is acquired in the acquisition time period, and the balancing is not performed in the balancing time period.

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

In one embodiment, obtaining the voltage rate of change value of each single battery in the battery pack comprises:

and in the charging or discharging process of the battery pack, determining the preset electric quantity charged or discharged to each single battery and the voltage variation of each single battery. The voltage variation is a difference between an initial terminal voltage before the single battery is charged or discharged with a preset electric quantity and a final terminal voltage after the single battery is charged or discharged with the preset electric quantity.

For each single battery in the battery pack, determining the voltage change rate of the single battery as the ratio of the voltage change quantity of the single battery to preset electric quantity.

In another embodiment, obtaining the voltage rate of change values of the individual cells in the battery pack comprises:

in the charging or discharging process of the battery pack, the preset charging or discharging time length of each single battery and the voltage variation of each single battery are determined. The voltage variation is the difference between the initial terminal voltage before the single battery is charged or discharged with the preset electric quantity and the final terminal voltage after the single battery is charged or discharged with the preset electric quantity;

for each single battery in the battery pack, determining the voltage change rate of the single battery as the ratio of the voltage change quantity of the single battery to the preset time length.

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 voltage change rate of the single batteries can be obtained according to the voltage and electric quantity change conditions and the method.

Due to the fact that under different SOC states, the change rate of the voltage of the single battery along with the charging and discharging time is different. Therefore, the embodiment of the disclosure can identify the SOC state difference of each single battery according to the difference of the voltage change rate of the battery, so as to identify the consistency difference of each single battery, and determine the balancing duty ratio of the single battery to be balanced.

In step S52, a reference voltage change rate value is determined from the voltage change rate value of each unit cell.

The reference voltage rate value may be a maximum value, a minimum value, or an average value among the voltage rate values of the individual unit cells.

In step S53, an equalization duty ratio of the to-be-equalized battery cell is determined according to the voltage change rate value of the to-be-equalized battery cell in the battery pack and the reference voltage change rate value. The equalization duty ratio is a ratio of a duration of the equalization period to a duration of the unit period.

In step S54, the equalization of the unit cells to be equalized is controlled in the equalization period of the unit cycle in accordance with the equalization duty ratio.

Referring to fig. 6, in an embodiment of the present disclosure, step S53 includes:

in step S61, the cell in the battery pack having the smallest difference between the voltage change rate value and the reference voltage change rate value is determined as the reference cell.

In step S62, when the initial terminal voltage of the single battery to be equalized is different from the initial terminal voltage of the reference battery, the equalization duty ratio of the single battery to be equalized is determined according to the initial terminal voltage of the single battery to be equalized and the initial terminal voltage of the reference battery.

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. 7, when the initial terminal voltage of the single battery to be equalized is different from the initial terminal voltage of the reference battery, the single battery is 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 balancing duty ratio of the single battery to be balanced can be further determined according to the electric quantity difference of the two single batteries.

In step S63, when the initial terminal voltage of the single battery to be equalized is the same as the initial terminal voltage of the reference battery, the equalization duty ratio of the single battery to be equalized is determined according to the final terminal voltage of the single battery to be equalized and the final terminal voltage of the reference battery.

As described above, the final terminal voltage is a voltage obtained by charging or discharging a predetermined amount of electricity to or from the battery cell based on the initial terminal voltage. Or the final terminal voltage is a voltage obtained by charging or discharging the single battery for a preset time length on the basis of the initial terminal voltage.

Referring to fig. 8, when there is no difference in the initial terminal voltages of the unit cells to be equalized and the reference cell, the rate of change in the voltage of the unit cells is mainly caused by the difference in the speed of change in the voltage during charging or discharging. Therefore, the balancing duty ratio of the single battery to be balanced can be determined according to the final end voltage of the single battery to be balanced and the final end voltage of the reference battery.

Referring to fig. 9, in one embodiment, the step S62 includes:

in step S91, a first SOC value corresponding to the initial terminal voltage value of the reference battery is determined based on the initial terminal voltage value of the reference battery and the OCV-SOC curve of the reference battery.

In one embodiment, the reference OCV value of the reference battery is determined based on an initial terminal voltage value of the reference battery and an internal resistance value of the reference battery. And determining the SOC value corresponding to the reference OCV value as a first SOC value according to the reference OCV value and an OCV-SOC curve of the reference battery.

In step S92, a second SOC value corresponding to the initial terminal voltage value of the single battery to be equalized is determined according to the initial terminal voltage value of the single battery to be equalized and the OCV-SOC curve corresponding to the single battery to be equalized.

In one embodiment, the OCV value of the single battery to be equalized is determined according to the initial terminal voltage value of the single battery to be equalized and the internal resistance value of the single battery to be equalized. And determining the SOC value corresponding to the OCV value as a second SOC value according to the OCV value and the OCV-SOC curve of the single battery to be balanced.

In step S93, determining an equalization duty ratio of the battery cell to be equalized according to the first SOC value and the second SOC value.

Referring to fig. 10, a graph of an open circuit voltage OCV versus a remaining capacity SOC of a unit cell according to an embodiment of the present disclosure is shown.

Hereinafter, a process of obtaining the SOC value by the voltage value and the internal resistance value will be described with reference to fig. 11 and equation (1):

referring to fig. 11 and equation (1), when the battery pack is in a discharging state or a charging state, the cell is equivalent to an ideal voltage source and is connected in series with a resistor R by using a cell internal resistance model. Then, for a single battery, the sampled voltage value V of the single battery can be obtained according to the formula (1)_L(i.e., load voltage value) to open circuit voltage value:

OCV＝V_L+I×R (1)

wherein, V_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.

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

After the Open Circuit Voltage (OCV) of the single battery is obtained, the SOC value corresponding to the single battery can be obtained according to the OCV-SOC curve of the single battery.

It should be understood that the OCV-SOC curve shown in fig. 10 may also be converted into a correspondence table of OCV and SOC, an OCV value corresponding to an SOC value, or an OCV range corresponding to an SOC value.

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

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

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

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

ΔQ＝ΔSOC×C_n (2)

where Δ Q is the difference in electrical quantities, Δ SOC is the difference in SOC between the first and second SOC values, C_nIs the available capacity of the single battery to be equalized.

Determining the balance duty ratio of the single battery to be balanced according to the formula (3):

τ＝(ΔQ/I)/t (3)

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

Referring to fig. 12, in one embodiment, the step S63 includes:

in step S121, a third SOC value corresponding to the final terminal voltage value of the reference battery is determined according to the final terminal voltage value of the reference battery and the open-circuit voltage OCV-remaining capacity SOC curve of the reference battery.

In one embodiment, a reference OCV value of the reference battery is determined according to a final terminal voltage value of the reference battery and an internal resistance value of the reference battery; and determining the SOC value corresponding to the reference OCV value as the third SOC value according to the reference OCV value and the OCV-SOC curve of the reference battery.

The SOC value of the single battery is obtained according to the voltage value of the single battery, the internal resistance value of the single battery, and the OCV-SOC curve corresponding to the single battery, which can refer to the above description and is not described herein again.

In step S122, a fourth SOC value corresponding to the final terminal voltage value of the single battery to be equalized is determined according to the final terminal voltage value of the single battery to be equalized and the OCV-SOC curve corresponding to the single battery to be equalized.

In one embodiment, the OCV value of the single battery to be equalized is determined according to the final end voltage value of the single battery to be equalized and the internal resistance value of the single battery to be equalized. And determining the SOC value corresponding to the OCV value of the single battery to be balanced as the fourth SOC value according to the OCV-SOC curve of the single battery to be balanced.

In step S123, determining a balancing duty ratio of the single battery to be balanced according to the third SOC value and the fourth SOC value.

In one embodiment, 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 third and fourth SOC values, and C_nThe available capacity of the single battery to be equalized is obtained. And then, 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.

After the balance duty ratio of the single battery to be balanced is determined, the time length of the acquisition time period and the time length of the balance time period are controlled according to the balance duty ratio under the condition of unit cycle setting, so that the balance efficiency is improved, and the balance cost is reduced.

In the embodiment of the present disclosure, before the step S53, determining the single battery to be equalized in the battery pack that needs to be equalized.

In an embodiment of the present disclosure, 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. 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.

Referring to fig. 13, in an embodiment of the present disclosure, the unit cells to be equalized are determined by:

in step S131, a difference between the performance parameter of the at least one unit cell and the reference value of the performance parameter is determined.

In step S132, the single battery, in which the difference between the performance parameter and the reference value of the performance parameter is greater than or equal to the equalization start threshold value, of the at least one single battery is determined as the single battery to be equalized.

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

As described above, when the performance parameter is voltage, the above-described step of determining the unit cells to be equalized is described with reference to fig. 14:

in step S141, a voltage difference value between the voltage value of at least one unit cell and the reference voltage value is determined.

In step S142, the single battery with the voltage difference between the voltage value and the reference voltage value being greater than or equal to the balancing start threshold value in the at least one single battery is determined as the single battery to be balanced that needs to be balanced.

When the reference voltage value is the minimum value among the voltage values of the respective unit cells, step S141 includes:

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

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

When the reference voltage value is the maximum value among the voltage values of the respective unit cells, step S141 includes:

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

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

When the reference voltage value is an average value of the voltage values of the respective unit cells, the step S141 includes:

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

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

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

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

The rate of change of charge amount (dq/dv) of the unit cell may be an amount of change in voltage at which a unit of a specified physical amount of the unit cell is changed. 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 (dt/dv) of the unit cell may be a time period required for a unit change in a specified physical quantity of the unit cell. For example, the present disclosure will be described taking as an example a charging time required for the voltage of the unit cell to rise by one unit voltage from the initial voltage, or a discharging time required for the voltage of the unit cell to fall by one unit voltage from the initial voltage.

TABLE 1

Therefore, when the equalization judgment is carried out by adopting the performance parameters of different batteries, the judgment is carried out according to the corresponding mode in the table 1, and the single batteries 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 S132 that there is no cell that needs to be equalized, the equalization determination continues based on the information collected in the next collection period. When the single batteries needing to be balanced are determined to be absent according to the information acquired in the acquisition time period, the control module does not act in the balancing time period, so that the balancing module corresponding to any battery is not started.

In an embodiment of the present disclosure, the balancing duty ratio of the single battery to be balanced is determined according to a voltage change rate value difference between the voltage change rate value of the single battery to be balanced and the reference voltage change rate value, and a preset corresponding relationship between the voltage change rate value difference and the balancing duty ratio. The corresponding relationship between the preset voltage rate difference value and the equalizing duty ratio may be a corresponding relationship table.

Equalization process

Fig. 15 is a schematic diagram of an equalizing module according to an embodiment of the disclosure. And controlling the single batteries to be balanced in the balancing time period of the unit cycle, wherein the balancing needs to be carried out in combination with the balancing judgment. In the step of equalization determination (as described in steps S131 and S132 above), it is determined whether the equalization manner of the single battery to be equalized is passive equalization (i.e., discharging the single battery to be equalized) or active equalization (i.e., charging the single battery to be equalized), and the corresponding equalization module is turned on.

Referring to fig. 15, 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, in the balancing time period of the unit cycle, 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. 15, 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. 15, 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. 15, when the generator 92 is an alternator, the balancing module further comprises a rectifier 93 in series with the generator 92, each charging branch 94 being in series with the rectifier 93. After the alternating current generated by the generator 92 is converted into direct current by the rectifier 93, the generator 92 can be used for charging the single battery to be equalized.

Referring to fig. 15, 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 charging the single batteries by the generator as shown in fig. 15, 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. 15, 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 in a balancing period of a unit cycle, and balancing is performed separately.

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

Referring to fig. 16, in step S161, the control module controls the control channel of the to-be-equalized single battery that needs to be equalized, and equalizes the to-be-equalized single battery in the equalization period.

In step S162, when a single balancing time period ends, the control module determines whether the balancing of all the single batteries to be balanced is completed, that is, whether the accumulated balancing time of all the single batteries to be balanced reaches the preset balancing time corresponding to each other. If the balancing time of all the single batteries to be balanced reaches the requirement, executing the step S164; if the equalization duration of any single battery to be equalized does not meet the requirement, step S163 is executed.

When the balancing processing is carried out on the single batteries to be balanced in the balancing time period, when the accumulated balancing time of any single battery to be balanced reaches the corresponding preset balancing time, the balancing of the single battery to be balanced is controlled to stop.

In step S163, when a single unit cycle is ended, if the accumulated equalization time of any single battery to be equalized does not reach the preset equalization time corresponding thereto, after the sampling time of the next unit cycle is ended, in the equalization time, the equalization of the single battery not reaching the equalization time is continuously controlled, and step S162 is executed.

In step S164, a new round of equalization judgment is started, and according to the battery information acquired in the acquisition time period, the single battery to be equalized which needs to be equalized is judged and the equalization duty ratio of each single battery to be equalized is determined.

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

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

Referring to fig. 17, in step S171, target parameter information of the battery to be equalized is acquired. The target parameter comprises any one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, rate of change of voltage, rate of change of electrical quantity, and rate of change of time.

In step S172, historical balancing duration and historical parameter information of the single battery to be balanced are obtained, where the historical parameter information is historical information of the target parameter information.

In step S173, the equalization time required for the current equalization of the single battery to be equalized is determined according to the target parameter information, the historical equalization time and the historical parameter information. The equalization duration is used as the preset equalization duration.

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

wherein, t_kThe equalization duration is the equalization time; t is t_k-1The historical balancing time length of the last balancing of the single battery to be balanced is obtained; delta S_kThe difference value between the target parameter of the single battery to be balanced and the reference value of the target parameter is the current moment; delta S_k-1The difference value between the target parameter of the single battery to be equalized and the reference value of the target parameter is the last equalization moment; c_kThe current available capacity of the single battery to be balanced is the current moment; c_k-1The historical available capacity of the single battery to be balanced is the last balancing moment.

Adjustment of equalized duty cycle

In an embodiment of the present disclosure, the equalization duty ratio obtained according to the above equation (3) is based on a preset equalization current, and the preset equalization current may be determined according to a resistance of the equalization module or an equalization current provided by the transmitter. In the actual balancing process, as the balancing proceeds, the resistance value of the resistor and the like may affect the balancing current. Therefore, referring to fig. 18, in an embodiment of the present disclosure, the method further includes the step of adjusting the equalization duty ratio according to the equalization current:

in step S181, in the balancing process of the single battery to be balanced, the balancing current of the single battery to be balanced is acquired.

The acquisition of the equalization current may be performed in the following manner: in the equalizing loop, a sampling resistor is connected in series, and equalizing current is obtained according to the sampled voltage value and the resistance value of the sampling resistor by detecting the voltage at two ends of the sampling resistor.

In step S182, when the balancing current is greater than or equal to the preset balancing current, reducing the balancing duty ratio of the single battery to be balanced; 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 one embodiment, the balancing duty ratio of the single battery to be balanced may be proportionally reduced or increased, for example, a ratio of the obtained balancing current to a preset balancing current is determined, and the balancing duty ratio is reduced or increased according to the ratio.

In one embodiment, the balancing duty ratio of the single battery to be balanced can be recalculated according to the balancing current and the above equation (3).

In an embodiment of the present disclosure, in the balancing process of the single battery to be balanced, when it is detected that any one of the performance parameters of the single battery to be balanced satisfies the balancing duty ratio adjustment condition corresponding to the performance parameter, the balancing duty ratio of the single battery to be balanced is adjusted.

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

In one embodiment, a performance parameter is determined from the performance parameters as a target performance parameter, and the balancing duty ratio is adjusted when the difference between the value of the target performance parameter of the single battery to be balanced and the reference value of the target performance parameter is larger or smaller than the difference at the beginning of balancing.

Adjusting the equalization duty cycle, including:

when the difference value between the target performance parameter value of the single battery to be balanced and the reference value of the target performance parameter is larger than the difference value at the beginning of balancing, increasing the balancing duty ratio;

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

In other embodiments, adjusting the equalization duty cycle comprises:

when the battery pack is in a charging state, if the value of the performance parameter of the single battery to be balanced in the balancing process is greater than or equal to a first preset threshold corresponding to the performance parameter, reducing the balancing duty ratio; or,

when the battery pack is in a discharging state, the value of the performance parameter of the single battery to be balanced in the balancing process is smaller than a second preset threshold corresponding to the performance parameter, and then the balancing duty ratio is reduced.

For example, when the performance parameter is voltage, when the battery pack is in a charging state, if the voltage of the single battery in the balancing process is higher than or equal to a first preset threshold, the balancing duty ratio is reduced; when the battery pack is in a discharging state, if the voltage of the single battery in the balancing process is lower than a second preset threshold value, the balancing duty ratio is reduced.

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

Correspondingly, the embodiment of the disclosure also provides a battery equalization system. This battery equalizing system includes: 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;

In one embodiment, the control module is configured to determine, during charging or discharging of the battery pack, a preset amount of electricity to be charged or discharged to each single battery, and a voltage variation of each single battery, where the voltage variation is a difference between an initial terminal voltage before the single battery is charged or discharged with the preset amount of electricity and a final terminal voltage after the single battery is charged or discharged with the preset amount of electricity;

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

In one embodiment, the control module is configured to determine, during charging or discharging of the battery pack, a preset charging or discharging time period for each single battery, and a voltage variation of each single battery, where the voltage variation is a difference between an initial terminal voltage before the preset charging or discharging time period for each single battery and a final terminal voltage after the preset charging or discharging time period for each single battery;

and for each single battery in the battery pack, determining the voltage change rate of the single battery as the ratio of the voltage change of the single battery to the preset time.

In one embodiment, the control module is configured to determine a cell in the battery pack with a smallest difference between a voltage change rate value and the reference voltage change rate value as a reference cell;

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 balancing duty ratio of the single battery to be balanced according to the initial end voltage of the single battery to be balanced and the initial end voltage of the reference battery;

and when the initial end voltage of the single battery to be balanced is the same as the initial end voltage of the reference battery, determining the balancing duty ratio of the single battery to be balanced according to the final end voltage of the single battery to be balanced and the final end voltage of the reference battery.

In one embodiment, the control module is configured to determine a first SOC value corresponding to an 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 balance duty ratio of the single battery to be balanced according to the first SOC value and the second SOC value.

In one embodiment, the control module is used for determining a reference OCV value of the reference battery 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 a second SOC value corresponding to the initial terminal voltage value of the single battery to be equalized according to the initial terminal voltage value of the single battery to be equalized and the OCV-SOC curve corresponding to the single battery to be equalized, wherein the determining step comprises the following steps:

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;

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 one embodiment, the control module 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 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.

In one embodiment, the control module is configured to determine a third SOC value corresponding to the final terminal voltage value of the reference battery according to the final terminal voltage value of the reference battery and an open-circuit voltage OCV-remaining capacity SOC curve of the reference battery;

determining a fourth SOC value corresponding to the final end voltage value of the single battery to be balanced according to the final end 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 balance duty ratio of the single battery to be balanced according to the third SOC value and the fourth SOC value.

In one embodiment, the control module is used for determining a reference OCV value of the reference battery according to a final terminal voltage value of the reference battery and an internal resistance value of the reference battery;

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

determining a fourth SOC value corresponding to the final end voltage value of the single battery to be balanced according to the final end voltage value of the single battery to be balanced and the OCV-SOC curve corresponding to the single battery to be balanced, wherein the fourth SOC value comprises the following steps:

determining an OCV value of the single battery to be balanced according to the final end voltage value of the single battery to be balanced and the internal resistance 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 fourth SOC value according to the OCV-SOC curve of the single battery to be balanced.

In one embodiment, the control module 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 third and fourth SOC values, and C_nThe available capacity of the single battery to be balanced is obtained;

In one embodiment, the control module 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,

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

In one embodiment, the control module is further configured to, in a balancing process of the to-be-balanced single battery, adjust a balancing duty ratio of the to-be-balanced single battery when it is detected that any one of performance parameters of the to-be-balanced single battery meets 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 one embodiment, the control module is configured to determine a minimum voltage change rate value among voltage change rate values of the individual batteries in the battery pack as the reference voltage change rate value; or,

determining the maximum voltage change rate value of the voltage change rate values of the single batteries in the battery pack as the reference voltage change rate value; or,

and determining the average value of the voltage change rate values of the single batteries in the battery pack as the reference voltage change rate value.

In one embodiment, the control module 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.

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

In one embodiment, the control module is connected with the acquisition module and the equalization module corresponding to the same single battery through one channel, and the acquisition module and the equalization module multiplex the channels in a time-sharing manner.

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

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

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

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

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

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

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

The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

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

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

Claims

1. A method of balancing a battery, comprising:

determining a reference voltage change rate value according to the voltage change rate value of each single battery, wherein the reference voltage change rate value is the maximum value, the minimum value or the average value of the voltage change rate values of each single battery;

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

determining the balancing duty ratio of the single battery to be balanced according to the voltage value of the single battery to be balanced in the battery pack and the voltage value of the reference battery, 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 of claim 1, wherein obtaining a voltage rate of change value for each cell in the battery pack comprises:

determining the preset electric quantity charged or discharged to each single battery and the voltage variation of each single battery in the charging or discharging process of the battery pack, wherein the voltage variation is the difference value of the initial terminal voltage before the preset electric quantity is charged or discharged to the single battery and the final terminal voltage after the preset electric quantity is charged or discharged to the single battery;

3. The method of claim 1, wherein obtaining a voltage rate of change value for each cell in the battery pack comprises:

in the charging or discharging process of the battery pack, determining preset charging or discharging time for each single battery and voltage variation of each single battery, wherein the voltage variation is a difference value between an initial terminal voltage before the preset charging or discharging time for each single battery and a final terminal voltage after the preset charging or discharging time for each single battery;

4. The method according to any one of claims 2 or 3, wherein the determining the balancing duty ratio of the single battery to be balanced according to the voltage value of the single battery to be balanced in the battery pack and the reference battery voltage value comprises:

5. The method as claimed in claim 4, wherein the determining the balancing duty ratio of the single battery to be balanced according to the initial terminal voltage of the single battery to be balanced and the initial terminal voltage of the reference battery comprises:

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 the OCV-SOC curve of the reference battery;

6. The method of claim 5, wherein determining a first SOC value corresponding to the initial terminal voltage value of the reference battery from the initial terminal voltage value of the reference battery and the OCV-SOC curve of the reference battery comprises:

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

7. The method according to claim 6, 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;

8. The method as claimed in claim 4, wherein the determining the balancing duty ratio of the single battery to be balanced according to the final terminal voltage of the single battery to be balanced and the final terminal voltage of the reference battery comprises:

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

9. The method of claim 8, wherein determining a third SOC value corresponding to the final terminal voltage value of the reference battery from the final terminal voltage value of the reference battery and the OCV-SOC curve of the reference battery comprises:

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

10. The method according to claim 9, wherein the step of determining the balancing duty cycle of the single battery to be balanced according to the third SOC value and the fourth SOC value comprises:

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 third and fourth SOC values, and C_nThe available capacity of the single battery to be balanced is obtained;

11. The method according to claim 7 or 10, characterized in that the method further comprises:

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

12. 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.

13. The method of claim 1, wherein obtaining the reference voltage rate of change value required for equalization comprises:

determining the minimum voltage change rate value of the voltage change rate values of the single batteries in the battery pack as the reference voltage change rate value; or,

14. The method of claim 1, 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.

15. 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 a voltage change rate value of each single battery according to battery information of each single battery of the battery pack, which is acquired in a sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and a balancing time period; determining a reference voltage change rate value according to the voltage change rate value of each single battery, wherein the reference voltage change rate value is the maximum value, the minimum value or the average value of the voltage change rate values of each single battery; determining the single battery with the minimum difference between the voltage change rate value and the reference voltage change rate value in the battery pack as a reference battery; determining the balancing duty ratio of the single battery to be balanced according to the voltage value of the single battery to be balanced in the battery pack and the voltage value of the reference battery, 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;

16. The system of claim 15, wherein the control module is configured to determine a preset amount of power to be charged or discharged to each cell during charging or discharging of the battery pack, and a voltage variation of each cell, where the voltage variation is a difference between an initial terminal voltage before the preset amount of power is charged or discharged to the cell and a final terminal voltage after the preset amount of power is charged or discharged to the cell;

17. The system of claim 15, wherein the control module is configured to determine a preset charging or discharging time period for each cell, and a voltage variation of each cell during the charging or discharging process of the battery pack, wherein the voltage variation is a difference between an initial terminal voltage before the preset charging or discharging time period for each cell and a final terminal voltage after the preset charging or discharging time period for each cell;

18. The system according to any one of claims 16 or 17, wherein the control module is configured to determine a cell in the battery pack having a smallest difference between the voltage change rate value and the reference voltage change rate value as a reference cell;

19. The system of claim 18, wherein the control module is configured to determine 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 OCV-SOC curve;

20. The system of claim 19, wherein said control module is configured to determine a reference OCV value of said reference battery based on an initial terminal voltage value of said reference battery and an internal resistance value of said reference battery;

21. The system of claim 20, 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;

22. The system according to claim 21, 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;

23. The system of claim 18, wherein the control module is configured to determine a third SOC value corresponding to the final terminal voltage value of the reference battery according to the final terminal voltage value of the reference battery and an OCV-SOC curve;

24. The system according to claim 15, 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.

25. The system of claim 15, wherein the control module is further configured to determine the single battery to be equalized from the battery pack according to performance parameters of each single battery in the battery pack, wherein the performance parameters include at least one of voltage, SOC, internal resistance, self-discharge rate, voltage change rate, charge change rate, and time change rate.

26. The system of claim 15, wherein the control module is connected with the acquisition module and the equalization module corresponding to the same battery 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 battery cell connected with the control module does not need equalization; or,

27. The system of claim 26, 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.

28. The system of claim 15, wherein the control module is connected to the collection module and the equalization module corresponding to the same cell through two channels.

29. The system of claim 28, 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.

30. A vehicle comprising a battery equalization system as claimed in any of claims 15-29.

31. 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 1-14.

32. An electronic device, comprising:

the computer-readable storage medium recited in claim 31; and