WO2019042364A1

WO2019042364A1 - Battery equalization method and system, vehicle, storage medium, and electronic device

Info

Publication number: WO2019042364A1
Application number: PCT/CN2018/103273
Authority: WO
Inventors: 罗红斌; 王超; 沈晓峰; 曾求勇; 刘苑红; 张祥
Original assignee: 比亚迪股份有限公司
Priority date: 2017-08-31
Filing date: 2018-08-30
Publication date: 2019-03-07
Also published as: CN110015171B; CN110015171A

Abstract

A battery equalization method comprises: obtaining load voltage values of cells to be equalized in a battery pack (104) (S51); obtaining reference load voltage values required for equalization (S52); determining, according to the load voltage values of the cells to be equalized and to the reference load voltage values, a target equalization duration of the cells to be equalized (S53); and equalizing, according to the target equalization duration, the cells to be equalized (S54). Also disclosed are a battery equalization system using the method, a vehicle using the battery equalization system, a storage medium storing a program executing the method, and an electronic device comprising the medium. The target equalization duration on which the equalization process is based is calculated according to the differences between the load voltage values of the cells to be equalized and the reference load voltage values, and therefore, the equalization duration is more accurate, thereby making the equalization process also more accurate so as to avoid that the equalization duration is too long or too short.

Description

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

Cross-reference to related applications

This application claims the priority of the Chinese patent application No. "201710775025.2" filed by the BYD Co., Ltd. on August 31, 2017, entitled "Battery equalization method, system, vehicle, storage medium and electronic equipment".

Technical field

The present application relates to the field of control technologies, and in particular, to a battery equalization method, system, vehicle, storage medium, and electronic device.

Background technique

Large-capacity batteries that provide power for electric vehicles are often referred to as power batteries. A vehicle power battery generally consists of a plurality of single cells connected in series to form a module. With the use of the battery, the difference between the individual cells gradually expands, and the consistency between the cells is poor. Due to the short board effect of the battery, the capacity of the battery pack is limited, so that the capacity of the battery pack cannot be fully exerted, resulting in the battery pack. The overall capacity is reduced. On the other hand, the gradual enlargement of the differences between the individual cells will cause over-charging of some single cells, over-discharge of some single cells, affecting battery life, damaging the battery, and possibly generating a large amount of heat to cause the battery. Burning or exploding.

Therefore, the effective balanced management of the electric vehicle power battery is beneficial to improve the consistency of each battery in the battery pack, reduce the battery capacity loss, extend the service life of the battery and the driving range of the electric vehicle, which is of great significance.

At present, the battery pack is balancedly managed, and the battery information of each single battery in the battery pack is usually collected in real time, and then according to the collected battery information, it is determined whether there is a need for the single battery to be balanced, and when there is a need for a single battery to be balanced. Balance the cells that need to be balanced. In the process of equalizing the single cells, if the equalization time of the single cells is too long, it will increase the inconsistency of each single cell in the battery pack in which it is located, resulting in lower equalization efficiency; if the equalization time of the single cells If it is too short, it will not reach the balance effect. Therefore, how to accurately determine the equalization time of the unit cells that need to be balanced is a problem to be solved.

Application content

It is an object of the present application to provide a battery equalization method, system, vehicle, and electronic device to optimize the battery equalization process.

In order to achieve the above object, a first aspect of the present application provides a battery equalization method, where the method includes:

Obtaining a load voltage value of the battery cell to be equalized in the battery pack;

Obtain the reference load voltage value required for equalization;

Determining, according to the load voltage value of the unit cell to be equalized and the reference load voltage value, a target equalization time of the unit to be balanced;

The cells to be equalized are equalized according to the target equalization duration.

Optionally, determining, according to the load voltage value of the to-be-equalized unit battery and the reference load voltage value, determining a target equalization duration of the to-be-equalized unit battery, including:

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

Determining, according to the load voltage value of the unit cell to be equalized and the OCV-SOC curve, a second SOC value corresponding to a load voltage value of the unit cell to be equalized;

Determining the target equalization duration based on the first SOC value and the second SOC value.

Optionally, the determining, according to the reference load voltage value and the OCV-SOC curve of the battery group, a first SOC value corresponding to the reference load voltage value, including:

Determining, as the reference battery, a single cell that minimizes a difference between a load voltage value in the battery pack and the reference load voltage value;

Determining a reference OCV value of the reference battery according to a load voltage value of the reference battery and an internal resistance value of the reference battery;

Determining, according to the reference OCV value and the OCV-SOC curve, a SOC value corresponding to the reference OCV value as the first SOC value;

Determining, according to the load voltage value of the cell to be balanced and the OCV-SOC curve, a second SOC value corresponding to a load voltage value of the cell to be balanced, including:

Determining an OCV value of the to-be-equalized unit battery according to a load voltage value of the unit cell to be balanced and an internal resistance value of the unit to be balanced;

And determining, according to the OCV-SOC curve, that the SOC value corresponding to the OCV value of the to-be-equalized unit cell is the second SOC value.

Optionally, the determining, according to the first SOC value and the second SOC value, the target equalization duration, including:

Determining the electric quantity difference according to ΔQ=ΔSOC×C _n , wherein ΔQ is the electric quantity difference, ΔSOC is a SOC difference value between the first SOC value and the second SOC value, and C _n is the to-be-balanced single Usable capacity of the body battery;

The target equalization duration is determined according to t = ΔQ / I, where t is the target equalization duration and I is the equalization current of the to-be-equalized unit cells.

Determining a third SOC value corresponding to the reference load voltage value according to the reference load voltage value and a correspondence between the load voltage and the SOC;

Determining, according to a load voltage value of the unit cell to be equalized, and a correspondence between the load voltage and the SOC, a fourth SOC value corresponding to a load voltage value of the unit cell to be equalized;

Determining the target equalization duration based on the third SOC value and the fourth SOC value.

Optionally, the determining, according to the third SOC value and the fourth SOC value, the target equalization duration, including:

The electric quantity difference is determined according to ΔQ=ΔSOC×C _n , wherein ΔQ is the electric quantity difference, ΔSOC is a SOC difference value between the third SOC value and the fourth SOC value, and C _n is the to-be-balanced single Usable capacity of the body battery;

The target equalization duration is determined according to t=ΔQ/I, where t is the target equalization duration, and I is the equalization current of the unit cell to be equalized.

Determining the to-be-balanced according to a preset load relationship between a load voltage difference between the load voltage value of the unit cell to be equalized and the reference load voltage value, and a difference between the load voltage difference and the target equalization time length. The target equalization time of the single battery.

Optionally, the reference load voltage value is a minimum value of load voltage values of the respective unit cells, a maximum value of load voltage values of the respective unit batteries, or an average value of load voltage values of the respective unit batteries.

Optionally, the controlling the equalization of the cells to be balanced according to the target equalization duration includes:

And if the reference load voltage value is a minimum value of the load voltage values of the single cells, controlling the battery to be equalized to discharge according to the target equalization time; or

And if the reference load voltage value is a maximum value of the load voltage values of the single cells, controlling the battery to be equalized according to the target equalization time; or

If the reference load voltage value is an average value of the load voltage values of the single cells, according to the target equalization time length, when the load voltage value of the battery cell to be equalized is greater than the reference load voltage value, The unit battery is discharged, and when the load voltage value of the unit to be balanced is less than the reference load voltage value, the unit battery is controlled to be charged.

Optionally, the method further includes:

Determining, according to battery parameter information of each unit battery in the battery pack, the unit to be equalized from the battery group, wherein the battery parameter information includes an SOC value, an internal resistance value, a self-discharge rate value, At least one of a voltage change rate, a power change rate, and a time change rate, the voltage change rate being used to characterize a change in a load voltage value of the single cell as a unit value of a physical quantity change, the rate of change in the charge The load voltage value of the single cell changes the amount of charge required to be charged or discharged, and the time change rate is a charge duration or a discharge time required to change a load voltage value of the single cell by a unit value.

A second aspect of the present application provides a battery equalization system, including:

Equalization module, acquisition module and control module,

The collecting module is configured to: obtain a load voltage value of a single battery to be balanced in the battery group;

The control module is configured to: obtain a reference load voltage value required for equalization, and determine a target equalization time of the to-be-equalized unit battery according to the load voltage value of the unit to be balanced and the reference load voltage value ;

The equalization module is configured to: equalize the to-equalize cells according to the target equalization duration.

Optionally, the control module is configured to:

Determining the to-be-balanced according to a load voltage difference between the load voltage value of the to-be-equalized cell and the reference load voltage value, and a correspondence between a preset load voltage difference and a target equalization time The target equalization time of the single battery.

Optionally, the control module is connected to an acquisition module and an equalization module corresponding to the same single cell through a channel, and the control module is configured to control when determining that the single battery connected to the control module does not need to be equalized. The control module is connected to a corresponding sampling module; or

The control module is further configured to: when the cell connected to the control module needs to be equalized, the acquiring module and the equalization module time-multiplex the channel.

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

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

Optionally, the control module includes a control chip, and the control chip is respectively connected to an acquisition module and an equalization module corresponding to the same single cell through two pins, and the two pins are connected to the two channels. A correspondence.

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

A fourth aspect of the present application provides an electronic device, including:

A computer readable storage medium as described in the third aspect of the present application;

One or more processors for executing a program in the computer readable storage medium.

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

Through the above technical solution, according to the load voltage value of the unit cell to be equalized in the battery pack and the reference load voltage value, the target equalization time of the unit cell to be equalized is determined, and then the unit that needs to be equalized is determined according to the determined target equalization time length. The battery is balanced. Since the target equalization time based on the equalization process is calculated according to the difference between the load voltage value of the cell to be equalized and the reference load voltage value, it is more accurate, thereby making the equalization process more accurate and avoiding the equalization time. A long or too short situation occurs.

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

DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, In the drawing:

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

2 is a schematic diagram of a battery equalization system in which two single cells share an equalization module according to an embodiment of the present application;

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

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

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

FIG. 6 is a schematic diagram of an equalization module according to an embodiment of the present application.

Detailed ways

The specific embodiments of the present application are described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are intended to be illustrative and not restrictive.

1 is a schematic diagram of a battery equalization system according to an embodiment of the present application. The battery equalization system includes a control module 101, an acquisition module 102, an equalization module 103, and a battery pack 104.

In one embodiment, each unit cell corresponds to one acquisition module 102 and one equalization module 103. The acquisition module 102 and the equalization module 103 corresponding to the same single cell are respectively connected to the control module 101 through different control channels. The control module may include a control chip, and the control chip is respectively connected to the acquisition module and the equalization module corresponding to the same single cell through two pins, and the two pins are in one-to-one correspondence with the two channels.

In this embodiment, the control module 101 controls the collection module 102 and the equalization module 103 to perform time-division according to the unit cycle, respectively, and performs battery information collection and battery equalization, so that battery information collection and equalization are performed in a time-sharing manner. Avoid the impact of equalizing current on the accuracy of battery information collection when battery information acquisition and equalization are performed simultaneously.

In one embodiment, as shown in FIG. 1, each of the cells in the battery is coupled to an acquisition module 102 and an equalization module 103, respectively. If the battery pack includes N single cells, there are N acquisition modules 102 and N equalization modules 103. Thus, the control module 101 passes through 2×N control channels, respectively, with N acquisition modules and N equalization modules. connection.

In other embodiments, different single cells may share an equalization module, for example, N single cells in a battery pack, may share the same equalization module, or each preset number (eg, 2, 3, or 5 equal) single cells share an equalization module and the like. When at least two of the multi-cell cells sharing one equalization module need to be equalized, the equalization module and each of the at least two single cells that need to be equalized are equalized during the equalization period of the unit period. The batteries are connected alternately.

Referring to FIG. 2, two single cells share an equalization module. When two cells of a single equalization module need to be equalized, the equalization module is alternately connected with each cell during an equalization period of a unit cycle. Alternate connections may be alternate connections at a certain period. For example, referring to FIG. 2, when the parallel switch 150 on the parallel branch 15 corresponding to one of the two single cells 111 is closed for 2 s under the control of the control module 14, the other of the two cells The parallel switch 150 on the parallel branch 15 corresponding to the unit cell 111 is disconnected for 2 s under the control of the control module 14. That is, the parallel switch 150 on the parallel branch 15 corresponding to each of the two single cells, in the equalization period, switches from the closed state to the open state every two seconds, or from the disconnected state. Switch to the closed state. Therefore, on the basis of the time-division of the acquisition module and the equalization module, during the equalization period, the single cells sharing the same equalization module are alternately connected with the shared equalization module to achieve equalization.

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

The battery equalization system includes a control module 301, an acquisition module 302, an equalization module 303, and a battery pack 304. Wherein, the battery pack 304 includes a plurality of unit cells connected in series. The control module 301 is connected to the acquisition module 302 and the equalization module 303 corresponding to the same single cell through a control channel 305. The control module is configured to connect the control control module to the corresponding sampling module when it is determined that the single battery connected to the control module does not need to be equalized; or the control module is further configured to determine the requirement of the single battery connected to the control module When the equalization is performed, the acquisition module and the equalization module time-multiplex the channel 305 according to the unit period.

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

One unit period includes: an acquisition period and an equalization period. The control module 301 controls the acquisition module 302 to sample the battery information of the single battery during the collection period to obtain the battery information of the single battery. The battery information includes at least one of the following: voltage, current, temperature, and the like. In one embodiment, the battery information may include only voltage values, whereby the voltage performance parameters of the single cells are obtained. In another embodiment, the battery information may also include a voltage value, a current value, a temperature value, and the like, thereby obtaining performance parameters such as SOC, internal resistance, and self-discharge rate of the single battery.

The control module 301 determines, according to the battery information of the single battery collected by the collection module 302, the cell to be equalized that needs to be balanced. The control module 301 controls an equalization module corresponding to the to-be-equalized unit cell to balance the cells to be equalized during the equalization period.

Therefore, in the embodiment of the present application, the acquisition module and the equalization module share the same control channel, and the control module controls the acquisition module and the equalization module, and the control channel is time-multiplexed according to the unit period, thereby avoiding battery information collection and equalization. In the process of performing, the influence of the equalization current on the accuracy of the battery information collection; on the other hand, compared with the embodiment shown in FIG. 1 above, the number of channels of the control module chip is reduced, and the hardware cost can be saved.

In one embodiment, a switch K is provided in the control channel shared by the acquisition module and the equalization module. The control module 301 is connected to the switch K, and the time-sharing is connected to the acquisition module 302 or the equalization module 303 by controlling the switch K. When the switch K is connected to the acquisition module 302, the control module 301 controls the acquisition module 302 to collect battery information for the single battery during the collection cycle. When the switch K is connected to the equalization module 303, the control module 301 controls the equalization module 303. The corresponding single cells are equalized.

In one embodiment, referring to FIG. 1, each of the cells in the battery is connected to an acquisition module 302 and an equalization module 303, respectively. If the battery pack includes N single cells, the number of the acquisition modules 302 is N, and the equalization module 303 is N. Thus, the control module 301 is connected to the acquisition module and the equalization module through N control channels.

Referring to FIG. 4, an exemplary schematic diagram of sharing an equalization module for two single cells is shown. When two cell units sharing one equalization module need to be equalized, the equalization module is alternately connected with each unit cell during the equalization period of the unit period. Alternate connections may be alternate connections at a certain period. Therefore, on the basis of the time-division of the acquisition module and the equalization module, during the equalization period, the single cells sharing the same equalization module are alternately connected with the shared equalization module to achieve equalization.

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

Referring to FIG. 5, based on the battery equalization system shown in any of the foregoing embodiments of FIG. 1, FIG. 2, FIG. 3 or FIG. 4, the battery equalization method according to an embodiment of the present application includes:

In step S51, acquiring a load voltage value of the battery cells to be equalized in the battery pack;

In step S52, a reference load voltage value required for equalization is obtained;

In step S53, determining a target equalization duration of the to-be-equalized unit battery according to the load voltage value of the unit cell to be equalized and the reference load voltage value;

In step S54, the cells to be equalized are equalized according to the target equalization duration.

Wherein, to obtain the load voltage value of the single cell to be balanced in the battery pack, it is necessary to first determine the battery to be equalized, that is, the single cell that needs to be balanced.

The reference load voltage value may be a load voltage value of any one of the battery cells in the battery pack, for example, a load voltage value of the single battery in which the load voltage value of the battery pack is the largest, or a single battery having the smallest load voltage value in the battery pack. The load voltage value, or the load voltage value of the single cell in the middle of the load voltage value in the battery pack (for the case where the battery pack includes an odd number of single cells).

The reference load voltage value may also be calculated according to the load voltage value of each single battery in the battery pack, for example, the average value of the load voltage values of the individual cells in the pool group, or the load voltage value row in the battery pack. The average value of the load voltage values of the two cell batteries in the middle (for the case where the battery pack includes an even number of cells).

After determining the cells that need to be equalized, it is also possible to determine the target equalization time of the cells that need to be equalized, and then equalize the cells that need to be equalized according to the determined target equalization time. The determination of the target equalization duration is determined according to the load voltage value of the single cell that needs to be balanced and the reference load voltage value.

Optionally, the target equalization time of the unit to be equalized is determined according to the load voltage value of the unit to be balanced and the reference load voltage value, and is not limited to the following three determination manners:

1) The first method of determination includes the following steps:

Determining, according to the reference load voltage value and the OCV-SOC curve of the battery pack, a first SOC value corresponding to the reference load voltage value; according to the load voltage value of the to-be-equalized unit battery and the OCV- a SOC curve, determining a second SOC value corresponding to a load voltage value of the unit cell to be equalized; and determining the target equalization time length according to the first SOC value and the second SOC value.

Optionally, determining, according to the reference load voltage value and an OCV-SOC curve of the battery group, a first SOC value corresponding to the reference load voltage value, including: loading a load voltage value in the battery pack The single cell having the smallest difference from the reference load voltage value is determined as a reference battery; determining a reference OCV value of the reference battery according to a load voltage value of the reference battery and an internal resistance value of the reference battery; Referring to the OCV value and the OCV-SOC curve, determining a SOC value corresponding to the reference OCV value as the first SOC value;

Determining, according to the load voltage value of the cell to be equalized and the OCV-SOC curve, a second SOC value corresponding to the load voltage value of the cell to be balanced, including: according to the to-be-balanced Determining an OCV value of the cell to be equalized by determining a load voltage value of the body battery and an internal resistance value of the cell to be balanced; determining an OCV value of the cell to be equalized according to the OCV-SOC curve The corresponding SOC value is the second SOC value.

In one embodiment of the present application, the OCV-SOC curve may be obtained by measurement. For example, for a single cell, in the process of changing its SOC value from 0 to 100%, every time a certain SOC value is separated, the open circuit voltage OCV of the battery is measured once, and then the OCV of each point is corresponding. The SOCs correspond one-to-one to form a SOC-OCV curve of the unit cell.

It should be understood that when measuring the open circuit voltage OCV, the load voltage of the single cell can be collected first, and then converted to the corresponding open circuit voltage OCV according to the formula (1).

Or, in another embodiment, the voltage collected at the moment when the cell to be balanced stops working and reaches a steady state, or the battery just starts to work is itself an open circuit voltage or can be approximated as an open circuit voltage, so in this case The OCV value of the unit cell to be equalized can be directly collected.

Or, in another embodiment, the voltage collected when the battery to be referenced stops working and reaches a steady state, or the battery just starts to work is itself an open circuit voltage or can be approximated as an open circuit voltage, so in this case, The OCV value of the reference battery is obtained directly.

Thereby, the first SOC value of the reference battery can be obtained according to the reference voltage value, the internal resistance value of the reference battery, and the OCV-SOC curve corresponding to the reference battery. The second SOC value of the cell to be equalized is obtained according to the voltage value of the cell to be balanced, the internal resistance of the cell to be balanced, and the OCV-SOC curve corresponding to the cell to be equalized.

After obtaining the first SOC value and the second SOC value, the following steps are performed:

The power difference is determined according to ΔQ=ΔSOC×C _n , where ΔQ is the power difference, ΔSOC is the SOC difference between the first SOC value and the second SOC value, and C _n is the available capacity of the unit battery to be equalized;

The target equalization duration is determined according to t=ΔQ/I, where t is the target equalization duration and I is the equalization current of the unit cells to be equalized.

2) The second method of determination includes the following steps:

In an embodiment of the present application, the correspondence between the load voltage difference and the target equalization time may be obtained by measurement. After obtaining the load voltage difference between the load voltage value of the unit cell to be equalized and the reference load voltage value, the correspondence between the load voltage difference value and the target equalization time length is queried, and the target equalization time length can be determined.

It should be understood that, referring to Table 1 below, when the battery performance parameters are SOC value, internal resistance value, self-discharge rate, voltage change rate, power change rate or time change rate, respectively, the correspondence table of the balance judgment and the equalization mode.

Among them, the self-discharge rate of the single cell is used to characterize the capacity loss and capacity loss rate of the single cell. In one embodiment, when the battery pack stops working and reaches a steady state (at time t1), the open circuit voltage value V1 of each battery cell of the battery pack is detected and recorded; when the battery pack starts again to start working (time t2), Detecting and recording the open circuit voltage value V2 of each unit battery of the battery pack; calculating the self-discharge rate η of each unit battery according to the open circuit voltage values of the individual cells obtained by the two tests, and calculating the self-discharge rate value η is :

(1) Based on the OCV-SOC curve of the battery, find corresponding SOC1 and SOC2 according to the detected V1 and V2;

(2) calculating the SOC change value ΔSOC of the battery according to SOC1 and SOC2;

(3) Calculate the battery capacity discharged from the battery self-discharge according to ΔSOC and the battery full capacity C, ΔQ=ΔSOC*C;

(4) Calculate the value of the self-discharge rate η of the battery: η = ΔQ / (t1 - t2).

The voltage change rate of the unit cell may be a voltage change amount when the unit of the specified physical quantity of the unit cell is changed. For example, in the present application, a predetermined amount of power is charged or discharged to a single battery, a voltage variation (dv/dq) of the single battery, or a preset time for charging or discharging the single battery, and a voltage change of the single battery. The amount (dv/dt) is taken as an example for explanation.

The rate of change in the amount of electricity of the unit cell may be the amount of change in the amount of electricity when the unit of the specified physical quantity of the unit cell changes. For example, in the present application, the amount of charge required to increase the voltage of the unit cell by one unit voltage from the initial voltage, or the amount of decrease in the voltage of the unit cell from the initial voltage by one unit voltage will be described as an example.

The time rate of change of the unit cells may be the length of time required for the unit of the specified physical quantity of the unit cells to change. For example, in the present application, the charging time required for the voltage of the unit cell to rise by one unit voltage from the initial voltage or the discharge time required for the voltage of the unit cell to decrease by one unit voltage from the initial voltage will be described as an example.

Table 1

Therefore, when different battery performance parameters are used for the equalization determination, the corresponding equalization determination method in Table 1 is used to determine the single cell in the battery pack that needs to be balanced.

It should be understood that if it is determined that there is no single cell that needs to be balanced, it is determined whether there is a cell that needs to be balanced. When it is determined that there is no single cell that needs to be equalized, the control module may not operate, so that the equalization module corresponding to any battery is not turned on.

FIG. 6 is a schematic diagram of an equalization module according to an embodiment of the present application. Controlling the cells to be equalized for equalization needs to be performed in conjunction with the above-described equalization judgment. According to the steps of the equalization judgment, it is determined that the equalization mode of the cells to be balanced is passive equalization (ie, discharging the cells to be equalized), or active equalization (ie, charging the cells to be equalized), and turning on the corresponding equalization module. .

Referring to FIG. 6, for passive equalization, the equalization module includes: a resistor 811, each of which corresponds to an equalization module, that is, a resistor is connected in parallel with each end of each unit cell.

For a cell to be balanced that requires passive equalization, the control module controls parallel circuit conduction between the cell to be equalized and its corresponding resistor to perform passive equalization of the cell. Referring to FIG. 6, the control module is turned on by controlling the switch module 812 to realize conduction of a parallel circuit between the cell to be equalized and its corresponding resistor.

The resistor 811 can be a fixed value resistor or a variable resistor. In one embodiment, the resistor 811 can be a positive temperature coefficient thermistor, which can be varied with temperature, thereby adjusting the equalization current generated during equalization, thereby automatically adjusting the heat generation of the battery equalization system, and finally The temperature of the battery equalization system is effectively controlled.

Referring to FIG. 6, for active equalization, the equalization module includes a charging branch 94 connected in parallel with each of the unit cells 95 in the battery pack. The charging branch 94 is in one-to-one correspondence with the unit cells 95, and each charging branch 94 is provided. Both are coupled to a generator 92 that is mechanically coupled to the engine 91 via a gear.

The control module controls the charging branch 94 corresponding to the battery to be equalized to be turned on for the unit to be balanced that needs to be actively equalized. When the engine 91 rotates, the generator 92 is driven to generate electricity, so that the electric power generated by the generator 92 is supplied to the unit cells to be equalized, so that the electric quantity of the unit to be equalized is increased.

Referring to FIG. 6, when the generator 92 is an alternator, the equalization module further includes a rectifier 93 in series with the generator 92, each of the charging branches 130 being connected in series with the rectifier 132. After the alternating current generated by the generator 92 is converted to direct current by the rectifier 93, the generator 92 can be enabled to charge the individual cells to be equalized.

Referring to FIG. 6, the control module can be turned on by controlling the switch 96 corresponding to the cell to be balanced, so that the charging branch corresponding to the cell to be balanced is turned on, and the active equalization of the cell to be equalized is performed.

In other embodiments, in addition to charging the unit cells with a generator as shown in FIG. 6, the unit cells to be equalized may be charged by the starter battery in the vehicle.

In another embodiment, in addition to the parallel resistor and the unit cell to be balanced, as shown in FIG. 6, the unit cell to be equalized can be connected in parallel with the starting battery of the vehicle, and the battery to be balanced can be charged. The battery is activated to achieve equalization of the cells to be balanced while effectively avoiding waste of energy.

As described above, in the embodiment of the present application, a plurality of single cells can share one equalization module. When at least two of the multi-cell cells sharing one equalization module need to be balanced, the equalization module and the Each of the at least two single cells that need to be balanced is alternately connected and equalized separately.

Correspondingly, the embodiment of the present application further provides a vehicle, including the battery equalization system described above.

Correspondingly, the embodiment of the present application further provides a computer readable storage medium, where computer program instructions are stored, and the program instructions are implemented by the processor to implement the battery balancing method described above.

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

The preferred embodiments of the present application are described in detail above with reference to the accompanying drawings. However, the present application is not limited to the specific details in the foregoing embodiments, and various simple modifications may be made to the technical solutions of the present application within the technical concept of the present application. These simple variations are within the scope of this application.

It should be further noted that the specific technical features described in the above specific embodiments may be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present application will not be further described in various possible combinations.

Claims

A battery equalization method, comprising:

Obtaining a load voltage value of the battery cell to be equalized in the battery pack;

Obtain the reference load voltage value required for equalization;

Determining, according to the load voltage value of the unit cell to be equalized and the reference load voltage value, a target equalization time of the unit to be balanced;

The cells to be equalized are equalized according to the target equalization duration.
The method according to claim 1, wherein the determining the target equalization duration of the to-be-equalized unit battery according to the load voltage value of the unit cell to be equalized and the reference load voltage value comprises:

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

Determining, according to the load voltage value of the unit cell to be equalized and the OCV-SOC curve, a second SOC value corresponding to a load voltage value of the unit cell to be equalized;

Determining the target equalization duration based on the first SOC value and the second SOC value.
The method according to claim 2, wherein the determining the first SOC value corresponding to the reference load voltage value according to the reference load voltage value and the OCV-SOC curve of the battery pack comprises:

Determining, as the reference battery, a single cell that minimizes a difference between a load voltage value in the battery pack and the reference load voltage value;

Determining a reference OCV value of the reference battery according to a load voltage value of the reference battery and an internal resistance value of the reference battery;

Determining, according to the reference OCV value and the OCV-SOC curve, a SOC value corresponding to the reference OCV value as the first SOC value;

Determining, according to the load voltage value of the cell to be balanced and the OCV-SOC curve, a second SOC value corresponding to a load voltage value of the cell to be balanced, including:

Determining an OCV value of the to-be-equalized unit battery according to a load voltage value of the unit cell to be balanced and an internal resistance value of the unit to be balanced;

And determining, according to the OCV-SOC curve, that the SOC value corresponding to the OCV value of the to-be-equalized unit cell is the second SOC value.
The method according to claim 2 or 3, wherein the determining the target equalization duration according to the first SOC value and the second SOC value comprises:

Determining the electric quantity difference according to ΔQ=ΔSOC×C n , wherein ΔQ is the electric quantity difference, ΔSOC is a SOC difference value between the first SOC value and the second SOC value, and C n is the to-be-balanced single Usable capacity of the body battery;

The target equalization duration is determined according to t=ΔQ/I, where t is the target equalization duration, and I is the equalization current of the unit cell to be equalized.
The method according to claim 1, wherein the determining the target equalization duration of the to-be-equalized unit battery according to the load voltage value of the unit cell to be equalized and the reference load voltage value comprises:

Determining a third SOC value corresponding to the reference load voltage value according to the reference load voltage value and a correspondence between the load voltage and the SOC;

Determining, according to a load voltage value of the unit cell to be equalized, and a correspondence between the load voltage and the SOC, a fourth SOC value corresponding to a load voltage value of the unit cell to be equalized;

Determining the target equalization duration based on the third SOC value and the fourth SOC value.
The method according to claim 5, wherein the determining the target equalization duration according to the third SOC value and the fourth SOC value comprises:

The electric quantity difference is determined according to ΔQ=ΔSOC×C n , wherein ΔQ is the electric quantity difference, ΔSOC is a SOC difference value between the third SOC value and the fourth SOC value, and C n is the to-be-balanced single Usable capacity of the body battery;

The target equalization duration is determined according to t=ΔQ/I, where t is the target equalization duration, and I is the equalization current of the unit cell to be equalized.
The method according to claim 1, wherein the determining the target equalization duration of the to-be-equalized unit battery according to the load voltage value of the unit cell to be equalized and the reference load voltage value comprises:

Determining the to-be-balanced according to a preset load relationship between a load voltage difference between the load voltage value of the unit cell to be equalized and the reference load voltage value, and a difference between the load voltage difference and the target equalization time length. The target equalization time of the single battery.
The method according to any one of claims 1 to 7, wherein the reference load voltage value is a minimum value among load voltage values of the individual cells, and a maximum value of load voltage values of the individual cells Or the average value of the load voltage values of the individual cells.
The method according to claim 1, wherein the controlling the equalization of the cells to be equalized according to the target equalization duration comprises:

And if the reference load voltage value is a minimum value of the load voltage values of the single cells, controlling the battery to be equalized to discharge according to the target equalization time; or

And if the reference load voltage value is a maximum value of the load voltage values of the single cells, controlling the battery to be equalized according to the target equalization time; or

If the reference load voltage value is an average value of the load voltage values of the single cells, according to the target equalization time length, when the load voltage value of the battery cell to be equalized is greater than the reference load voltage value, The unit battery is discharged, and when the load voltage value of the unit to be balanced is less than the reference load voltage value, the unit battery is controlled to be charged.
The method according to any one of claims 1-9, wherein the method further comprises:

Determining, according to battery parameter information of each unit battery in the battery pack, the unit to be equalized from the battery group, wherein the battery parameter information includes an SOC value, an internal resistance value, a self-discharge rate value, At least one of a voltage change rate, a power change rate, and a time change rate, the voltage change rate being used to characterize a change in a load voltage value of the single cell as a unit value of a physical quantity change, the rate of change in the charge The load voltage value of the single cell changes the amount of charge required to be charged or discharged, and the time change rate is a charge duration or a discharge time required to change a load voltage value of the single cell by a unit value.
A battery equalization system, comprising:

Equalization module, acquisition module and control module,

The collecting module is configured to: obtain a load voltage value of a single battery to be balanced in the battery group;

The control module is configured to: obtain a reference load voltage value required for equalization, and determine a target equalization time of the to-be-equalized unit battery according to the load voltage value of the unit to be balanced and the reference load voltage value ;

The equalization module is configured to: equalize the to-equalize cells according to the target equalization duration.
The battery equalization system according to claim 11, wherein the control module is configured to:

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

Determining, according to the load voltage value of the unit cell to be equalized and the OCV-SOC curve, a second SOC value corresponding to a load voltage value of the unit cell to be equalized;

Determining the target equalization duration based on the first SOC value and the second SOC value.
The battery equalization system according to claim 12, wherein the control module is configured to:

Determining, as the reference battery, a single cell that minimizes a difference between a load voltage value in the battery pack and the reference load voltage value;

Determining a reference OCV value of the reference battery according to a load voltage value of the reference battery and an internal resistance value of the reference battery;

Determining, according to the reference OCV value and the OCV-SOC curve, a SOC value corresponding to the reference OCV value as the first SOC value;

Determining an OCV value of the to-be-equalized unit battery according to a load voltage value of the unit cell to be balanced and an internal resistance value of the unit to be balanced;

And determining, according to the OCV-SOC curve, that the SOC value corresponding to the OCV value of the to-be-equalized unit cell is the second SOC value.
The battery equalization system according to claim 12 or 13, wherein the control module is configured to:

Determining the electric quantity difference according to ΔQ=ΔSOC×C n , wherein ΔQ is the electric quantity difference, ΔSOC is a SOC difference value between the first SOC value and the second SOC value, and C n is the to-be-balanced single Usable capacity of the body battery;

The target equalization duration is determined according to t=ΔQ/I, where t is the target equalization duration, and I is the equalization current of the unit cell to be equalized.
The battery equalization system according to claim 11, wherein the control module is configured to:

Determining a third SOC value corresponding to the reference load voltage value according to the reference load voltage value and a correspondence between the load voltage and the SOC;

Determining, according to a load voltage value of the unit cell to be equalized, and a correspondence between the load voltage and the SOC, a fourth SOC value corresponding to a load voltage value of the unit cell to be equalized;

Determining the target equalization duration based on the third SOC value and the fourth SOC value.
The battery equalization system according to claim 15, wherein the control module is configured to:

The electric quantity difference is determined according to ΔQ=ΔSOC×C n , wherein ΔQ is the electric quantity difference, ΔSOC is a SOC difference value between the third SOC value and the fourth SOC value, and C n is the to-be-balanced single Usable capacity of the body battery;

The target equalization duration is determined according to t=ΔQ/I, where t is the target equalization duration, and I is the equalization current of the unit cell to be equalized.
The battery equalization system according to claim 11, wherein the control module is configured to:

Determining the to-be-balanced according to a load voltage difference between the load voltage value of the to-be-equalized cell and the reference load voltage value, and a correspondence between a preset load voltage difference and a target equalization time The target equalization time of the single battery.
The battery equalization system according to any one of claims 11-17, wherein the control module is connected to an acquisition module and an equalization module corresponding to the same single cell through a channel, and the control module is used for determining When the single battery connected to the control module does not need to be equalized, the control module is controlled to be connected with the corresponding sampling module; or

The control module is further configured to: when the cell connected to the control module needs to be equalized, the acquiring module and the equalization module time-multiplex the channel.
The battery equalization system according to claim 18, wherein the control module comprises a control chip, and the control chip is connected to the acquisition module and the equalization module corresponding to the same single cell through one pin and the one channel. .
The battery equalization system according to any one of claims 11-17, wherein the control module is respectively connected to the acquisition module and the equalization module corresponding to the same single cell through two channels.
The battery equalization system according to claim 20, wherein the control module comprises a control chip, and the control chip is respectively connected to an acquisition module and an equalization module corresponding to the same single cell through two pins, Two pins are in one-to-one correspondence with the two channels.
A computer readable storage medium having stored thereon computer program instructions, wherein the program instructions, when executed by a processor, implement the method of any of claims 1-10.
An electronic device, comprising:

The computer readable storage medium of claim 22;

One or more processors for executing a program in the computer readable storage medium.
A vehicle characterized by comprising: a battery pack and the battery equalization system according to any one of claims 11-21.