CN110015177B

CN110015177B - Battery equalization method, system, vehicle, storage medium and electronic device

Info

Publication number: CN110015177B
Application number: CN201710776098.3A
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: 2022-10-18
Anticipated expiration: 2037-08-31
Also published as: CN110015177A; WO2019042399A1

Abstract

The disclosure relates to a battery equalization method, a system, a vehicle, a storage medium and an electronic device, wherein the method comprises the following steps: acquiring the SOC value of a single battery to be balanced in a battery pack; acquiring a reference SOC value required by balancing; determining a target equalization time length of the single battery to be equalized according to the SOC value of the single battery to be equalized and the reference SOC value; and controlling the balancing of the single batteries to be balanced according to the target balancing duration. The target equalization time length based on the equalization process is calculated according to the difference value between the SOC value of the single battery to be equalized and the reference SOC value, so that the equalization process is more accurate, and the situation that the equalization time length is too long or too short is avoided.

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 generally comprises a module formed by connecting a plurality of single batteries in series. With the use of batteries, the difference between the single batteries is gradually enlarged, the consistency between the single batteries is poor, the capacity of the battery pack is limited due to the short plate effect of the batteries, the capacity of the battery pack cannot be fully exerted, and the whole capacity of the battery pack is reduced. On the other hand, the gradual expansion of the difference between the single batteries may cause overcharge of some single batteries, over-discharge of some single batteries, affect the service life of the batteries, damage the batteries, and generate a large amount of heat to cause combustion or explosion of the batteries.

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

At present, balancing management is performed on a battery pack, battery information of each single battery in the battery pack is usually acquired in real time, whether the single battery needs balancing or not is determined according to the acquired battery information, and when the single battery needs balancing, the single battery needing balancing is balanced. In the process of balancing the single batteries, if the balancing time of the single batteries is too long, the inconsistency of each single battery in the battery pack where the single batteries are located is increased, and the balancing efficiency is low; if the equalization time of the single battery is too short, the equalization effect cannot be achieved. Therefore, how to accurately determine the balancing time of the single battery needing balancing is a problem to be solved.

Disclosure of Invention

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

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

acquiring the SOC value of a single battery to be balanced in a battery pack;

acquiring a reference SOC value required by balancing;

determining a target equalization time length of the single battery to be equalized according to the SOC value of the single battery to be equalized and the reference SOC value;

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

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

a balancing module, an acquisition module and a control module,

the acquisition module is used for: acquiring the SOC value of a single battery to be balanced in a battery pack;

the control module is used for: acquiring a reference SOC value required by balancing, and determining a target balancing time length of the single battery to be balanced according to the SOC value of the single battery to be balanced and the reference SOC value;

the equalization module is configured to: and balancing the single batteries to be balanced according to the target balancing duration.

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

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

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

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

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

Through the technical scheme, the target equalization time length of the single battery to be equalized is determined according to the SOC value and the reference SOC value of the single battery to be equalized in the battery pack, and then the single battery to be equalized is equalized according to the determined target equalization time length. The target equalization time length based on the equalization process is calculated according to the difference value between the SOC value of the single battery to be equalized and the reference SOC value, so that the equalization process is more accurate, and the situation that the equalization time length is too long or too short is avoided.

Additional features and advantages of the present 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, but do not constitute a limitation of 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 diagram of a battery equalization method according to an embodiment of the disclosure;

fig. 6 is a schematic diagram of an OCV-SOC curve of a unit cell.

Fig. 7 is a schematic diagram of a battery internal resistance model according to an embodiment of the disclosure.

Fig. 8 is a schematic diagram of an equalization module according to an embodiment of the present disclosure.

Detailed Description

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

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

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

In this embodiment, the control module 101 controls the acquisition module 102 and the equalization module 103 to be turned on 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 and equalization of the battery information are performed in a time-sharing manner. The influence of the equalizing current on the accuracy of battery information acquisition is avoided when the battery information acquisition and the equalization are simultaneously carried out.

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

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

Referring to fig. 2, two single batteries share one balancing module, and when two single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected with each single battery in a balancing period of a unit cycle. The alternate 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 on 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 to the acquisition module 302, the control module 301 controls the acquisition module 302 to acquire battery information of the single battery in an acquisition cycle; when the switch K is connected to the balancing module 303, the control module 301 controls the balancing module 303 to balance the corresponding single battery.

In one embodiment, referring to fig. 1, each cell of the battery is connected to an acquisition module 302 and an equalization module 303, respectively. If the battery pack comprises 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 with the acquisition modules and the equalization modules through N control channels respectively.

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 connections may be connections that alternate according to a certain periodicity. Therefore, on the basis of time-sharing conduction of the acquisition module and the equalization module, the single batteries sharing the same equalization module are alternately connected with the shared equalization module during the equalization time period, and equalization is realized.

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

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

in step S51, acquiring an SOC value of a single battery to be equalized in the battery pack;

in step S52, a reference SOC value required for equalization is acquired;

in step S53, determining a target equalization duration of the single battery to be equalized according to the SOC value of the single battery to be equalized and the reference SOC value;

in step S54, balancing of the single battery to be balanced is controlled according to the target balancing duration.

First, step S51 will be explained.

In one embodiment, the method of calculating the SOC value comprises a first calculation mode corresponding to the intervals (0, soc1) and (SOC 2, 100%) and a second calculation mode corresponding to the intervals (SOC 1, SOC 2);

accordingly, step S51 includes:

for any single battery in the battery pack, determining the SOC value of the single battery according to the first calculation mode;

and when the SOC value determined according to the first calculation mode belongs to the interval (SOC 1, SOC 2), re-determining the SOC value of the single battery according to the second calculation mode.

Optionally, the first calculation manner is a manner adopted by the single battery to calculate the SOC value last time.

Optionally, the first calculation method is an ampere-hour integral method or an ampere-hour integral combined voltage correction method, and the second calculation method is a calculation method different from the first calculation method in the ampere-hour integral method and the ampere-hour integral combined voltage correction method.

The ampere-hour integration method is to integrate the acquired current value of the single battery with time to obtain the SOC value of the single battery; the ampere-hour integration combined voltage correction method is that firstly, an ampere-hour integration method is adopted to calculate the SOC value of a single battery, then the calculated SOC value is corrected by using the load voltage value of the single battery, and the corrected SOC value is used as the final SOC value of the single battery.

The embodiment of the present disclosure considers that there is an OCV plateau on the OCV-SOC curve of the unit cell, and the variation amplitude of the OCV value is small in the OCV plateau, and for example, fig. 6 is a schematic diagram of the OCV-SOC curve of the unit cell. As shown in fig. 6, in the [ SOC1, SOC2] section, the magnitude of variation in OCV values of the unit cells is small. Therefore, the SOC value of the battery cell cannot be accurately calculated by using the OCV value in the OCV plateau, and the battery cell requiring equalization cannot be accurately determined.

The OCV value is an open circuit voltage value of the unit cell, and is different from a load voltage value. Referring to fig. 7 and equation (1), when the battery pack is in a discharging state or a charging state, the single battery is equivalent to an ideal voltage source and is connected in series with a resistor R by using a battery internal resistance model. Then, for a single battery, the sampled voltage value V of the single battery can be obtained according to the formula (1) _L (i.e., load voltage value) to open circuit voltage value:

OCV＝V _L +I×R (1)

wherein, V _L The load voltage value collected by the collecting module in the collecting time period; i is the discharge 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: thevenin model, PNGV model and the like, and the acquired load voltage of the single battery is converted into open-circuit voltage.

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

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

Therefore, the load voltage value is collected, and the following relationship exists between the load voltage value and the OCV value:

OCV value = load voltage value + internal battery resistance + battery charging current or discharging current

In general, the internal resistance of the battery and the charging current or the discharging current of the battery are constant, and therefore, the difference between the OCV value and the load voltage value is also constant, and when the magnitude of the change in the OCV value is small, the magnitude of the change in the load voltage value is also small.

In order to accurately calculate the SOC value of the single battery, the method provided by the disclosure does not adopt the ampere-hour integration combined with the voltage correction method to calculate the SOC value in the OCV plateau period, and adopts the ampere-hour integration method to calculate the SOC value, so that the inaccuracy of the calculated SOC value caused by the adoption of the ampere-hour integration combined with the voltage correction method to calculate the SOC value in the OCV plateau period is avoided.

The present disclosure also considers that the magnitude of the change in the OCV values is large in the non-OCV plateau period, and for example, as shown in fig. 6, the magnitude of the change in the OCV values of the unit cells is large in the [0, soc1] and [ SOC2,1] sections. Therefore, in the non-OCV plateau period, the ampere-hour integration combined with the voltage correction method is more accurate than the ampere-hour integration method, so that the method for calculating the SOC value of the single battery by using the OCV value in the non-OCV plateau period is provided.

According to the OCV-SOC curve of the single battery, the value range of the SOC value of the single battery is divided into three intervals: a first interval, a second interval, and a third interval, where the second interval is an SOC interval corresponding to the OCV plateau period, for example, an [ SOC1, SOC2] interval in fig. 6; the first and third intervals are SOC intervals corresponding to non-OCV plateau periods, such as [0, soc1] intervals and [ SOC2,1] intervals in fig. 6. The embodiment of the disclosure provides that an ampere-hour integration method is adopted to calculate the SOC value of a single battery in an SOC interval corresponding to an OCV platform period, and an ampere-hour integration method is adopted to calculate the SOC value of the single battery in an SOC interval corresponding to a non-OCV platform period in combination with a voltage correction method. The OCV is an Open Circuit Voltage (Open Circuit Voltage), and the SOC is a remaining battery capacity (State of Charge).

In the embodiment of the present disclosure, since the voltage change rate is large in the first interval and the third interval, the SOC value of the battery may be calculated by performing correction by using an ampere-hour integration method and combining the real-time voltage (load voltage at this time) of the battery. In the second interval, the accuracy of the introduced voltage quantity calculation SOC value is not high due to the small battery voltage change rate, so that the SOC value can be directly calculated by adopting an ampere-hour integration method. By means of the method, how to obtain the SOC value of the single battery can be further determined according to different SOC value intervals of the single battery, so that the obtained SOC value of the single battery is accurate, and the determined single battery needing to be balanced is accurate.

In another embodiment, at the moment when the battery just works, the SOC value of the battery can be calculated by using an open-circuit voltage method, that is, the voltage value of the battery (equivalent to the open-circuit voltage value at this time) is collected, and the SOC value of the battery can be calculated by looking up the OCV-SOC correspondence relationship.

For any single battery in the battery pack, firstly, calculating the SOC value of the single battery by adopting any one of an ampere-hour integral method and an ampere-hour integral combined voltage correction method, wherein the calculation mode adopted at the moment is the first calculation mode. Then judging whether the calculated SOC value belongs to an SOC interval corresponding to an OCV platform period or not, if not, indicating that the calculated SOC value belongs to an SOC interval corresponding to a non-OCV platform period, and if so, recalculating the SOC value of the single battery according to the ampere-hour integration and voltage correction method, and optionally, in this case, if the SOC value of the single battery is recalculated, using the ampere-hour integration and voltage correction method as a first calculation mode; if the calculated SOC value belongs to the SOC interval corresponding to the OCV plateau, it indicates that the calculated SOC value is accurate, and it is not necessary to recalculate the SOC value of the battery cell.

Or, judging whether the calculated SOC value belongs to an SOC interval corresponding to a non-OCV plateau, and if the calculated SOC value does not belong to an SOC interval corresponding to a non-OCV plateau, indicating that the calculated SOC value belongs to an SOC interval corresponding to an OCV plateau, and if so, recalculating the SOC value of the cell according to the ampere-hour integration method as the SOC interval corresponding to the OCV plateau is more accurate than the ampere-hour integration method combined with the voltage correction method; if the calculated SOC value belongs to the SOC interval corresponding to the non-OCV plateau, it indicates that the calculated SOC value is accurate, and it is not necessary to recalculate the SOC value of the battery cell.

The above is the overall process of calculating the SOC value of the unit battery provided by the present disclosure.

In step S52, the reference SOC value may be an SOC value of any one of the unit cells in the battery pack, for example: the SOC value of the cell having the largest SOC value in the battery pack, or the SOC value of the cell having the smallest SOC value in the battery pack, or the SOC value of the cell having the SOC value aligned in the middle in the battery pack (for the case where the battery pack includes an odd number of cells).

The reference SOC value may also be calculated according to the SOC values of the individual cells in the battery pack, for example: the average value of the SOC values of the respective unit cells in the battery pack, or the average value of the SOC values of the two unit cells in the battery pack having the SOC values arranged at the middle (for the case where the battery pack includes an even number of unit cells).

Determining a target equalization time length of the single battery to be equalized according to the SOC value and the reference SOC value of the single battery to be equalized, wherein the target equalization time length is determined in the following two determination modes:

1) The first way of determining comprises the following steps:

as Δ Q = Δ SOC × C _n Determining the electric quantity difference, wherein delta Q is the electric quantity difference, delta SOC is the SOC difference value between the SOC value of the single battery to be balanced and the reference SOC value, and C _n The available capacity of the single battery to be balanced; and determining a target equalization time length according to t = delta Q/I, wherein t is the target equalization time length, and I is the equalization current of the single battery to be equalized.

2) The second determination method includes the steps of:

and determining the target equalization time length of the single battery to be equalized according to the SOC difference between the SOC value of the single battery to be equalized and the reference SOC value and the corresponding relation between the preset SOC difference and the target equalization time length.

In one embodiment of the present disclosure, the correspondence between the SOC difference value and the target equalization duration is obtained through measurement. After the SOC difference between the SOC value of the single battery to be balanced and the reference SOC value is obtained, the corresponding relation between the SOC difference and the target balancing duration is inquired, and the target balancing duration can be determined.

And the balancing process of the single batteries needing balancing is different when the reference SOC values are different. Hereinafter, the reference SOC values are respectively the minimum value, the maximum value, and the average value among the SOC values of the respective unit cells in the assembled battery, and the description will be given.

1) And under the condition that the reference SOC value is the minimum value of the SOC values of the single batteries in the battery pack, controlling the single batteries to be balanced to discharge according to the target balancing time length.

Specifically, when the reference SOC value is the minimum value among the SOC values of the individual batteries in the battery pack, only the SOC value of the individual battery with the largest SOC value in the battery pack may be subtracted from the reference SOC value, and it may be determined whether the individual battery with the largest SOC value in the battery pack is the individual battery requiring equalization. This embodiment can only determine if one cell needs to be balanced.

When the reference SOC value is the minimum value among the SOC values of the individual batteries in the battery pack, the difference between the SOC values of the individual batteries other than the individual battery with the minimum SOC value in the battery pack and the reference SOC value may be made, and it may be determined whether the individual batteries other than the individual battery with the minimum SOC value in the battery pack are the individual batteries requiring equalization. This embodiment is a batch determination method, and can determine whether the other cells except the cell with the smallest SOC value in the battery pack are the cells that need to be balanced at one time.

When the reference SOC value is the minimum value among the SOC values of the individual cells in the battery pack, the process of balancing the individual cells to be balanced is: no matter the battery pack is in a charging state or a discharging state, passive equalization is adopted, and the single batteries needing equalization are discharged.

2) And under the condition that the reference SOC value is the maximum value of the SOC values of all the single batteries in the battery pack, controlling the charging of the single batteries to be equalized according to the target equalization duration.

Specifically, when the reference SOC value is the maximum value among the SOC values of the individual batteries in the battery pack, only the SOC value of the individual battery with the minimum SOC value in the battery pack may be subtracted from the reference SOC value, and it may be determined whether the individual battery with the minimum SOC value in the battery pack is the individual battery requiring equalization. This embodiment can only determine if one cell needs to be balanced.

When the reference SOC value is the maximum value among the SOC values of the individual batteries in the battery pack, the difference between the SOC values of the individual batteries other than the individual battery having the maximum SOC value in the battery pack and the reference SOC value may be made, and it may be determined whether the individual batteries other than the individual battery having the minimum SOC value in the battery pack are the individual batteries requiring equalization. This embodiment is a batch determination method, and can determine whether or not the other cells in the battery pack, except the cell with the largest SOC value, are the cells that need to be balanced at one time.

In the case that the reference SOC value is the maximum value among the SOC values of the individual cells in the battery pack, the process of equalizing the individual cells requiring equalization is as follows: no matter the battery pack is in a charging state or a discharging state, active equalization is adopted to charge the single batteries needing equalization.

3) And under the condition that the reference SOC value is the average value of the SOC values of the single batteries in the battery pack, controlling the single batteries to discharge when the SOC values of the single batteries to be balanced are larger than the reference SOC value according to the target balancing duration, and controlling the single batteries to charge when the SOC values of the single batteries to be balanced are smaller than the reference SOC value.

Specifically, when the reference SOC value is an average value of the SOC values of the individual batteries in the battery pack, the SOC value of each individual battery in the battery pack may be subtracted from the reference SOC value, so as to determine whether each individual battery in the battery pack is an individual battery that needs to be balanced. The embodiment is a batch judgment mode, and can judge whether each single battery in the battery pack is a single battery needing to be balanced at one time.

When the reference SOC value is an average value of the SOC values of the individual cells in the battery pack, the process of equalizing the individual cells to be equalized is as follows: whether the battery pack is in a charging state or a discharging state, the single batteries of which the SOC values are larger than the average value in the single batteries needing to be balanced adopt passive balancing, and the single batteries of which the SOC values are larger than the average value in the single batteries needing to be balanced are discharged; and actively balancing the single batteries with the SOC values smaller than the average value in the single batteries needing to be balanced, and charging the single batteries with the SOC values smaller than the average value in the single batteries needing to be balanced.

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

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

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

(2) Calculating the SOC change value delta SOC of the battery according to the SOC1 and the SOC2;

(3) Calculating the battery capacity discharged by the battery through self-discharge according to the delta SOC and the full-capacity C of the battery, wherein delta Q = delta SOC C;

(4) Calculating the value of the self-discharge rate eta of the battery: η = Δ Q/(t 1-t 2).

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

The rate of change of charge (dq/dv) of the unit cell may be an amount of change in charge when a unit of a specified physical quantity of the unit cell is changed. For example, the present disclosure will be described by taking as an example the amount of electricity charged necessary for the voltage of the unit cell to rise by one unit voltage from the initial voltage, or the amount of electricity decreased by the voltage of the unit cell to fall by one unit voltage from the initial voltage.

The time change rate (dt/dv) of the unit cell may be a time period required for a unit change of a specific 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 different battery performance parameters are adopted for equalization judgment, the equalization judgment is carried out according to the corresponding equalization judgment method in the table 1, and the single batteries needing equalization in the battery pack are determined.

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

Fig. 8 is a schematic diagram of an equalizing module according to an embodiment of the disclosure. And controlling the single batteries to be balanced, wherein the balancing judgment needs to be combined. According to the step of equalization judgment, whether the equalization mode of the single battery to be equalized is passive equalization (namely, the single battery to be equalized is discharged) or active equalization (namely, the single battery to be equalized is charged) is determined, and the corresponding equalization module is conducted.

Referring to fig. 8, for passive equalization, the equalization module includes: and each single battery corresponds to one balancing module, namely, two ends of each single battery are connected with one resistor in parallel.

For the single battery to be balanced which needs to be passively balanced, the control module controls the conduction of a parallel loop between the single battery to be balanced and the corresponding resistor of the single battery to be balanced so as to execute the passive balancing of the single battery. Referring to fig. 8, the control module controls the switch module 812 to be turned on, so as to implement the conduction of the parallel loop between the single battery to be balanced and the corresponding resistor.

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

Referring to fig. 8, 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. 8, when the generator 92 is an alternator, the balancing module further comprises a rectifier 93 in series with the generator 92, each charging branch 130 being connected in series with said rectifier 132. After the alternating current generated by the generator 92 is converted into direct current by the rectifier 93, the generator 92 can be used for charging the single battery to be equalized.

Referring to fig. 8, the control module may control the switch 96 corresponding to the single battery to be equalized to be turned on, so that the charging branch corresponding to the single battery to be equalized is turned on, and active equalization of the single battery to be equalized is performed.

In other embodiments, in addition to the charging of the single batteries by the generator shown in fig. 8, 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 shown in fig. 8, 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 in a plurality of single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected to each single battery in the at least two single batteries that need to be balanced to perform balancing respectively.

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

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

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

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

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

Claims

1. A method of balancing a battery, comprising:

acquiring the SOC value of a single battery to be balanced in a battery pack;

acquiring a reference SOC value required by balancing;

controlling the balance of the single batteries to be balanced according to the target balancing duration;

the method of calculating the SOC value comprises a first calculation mode corresponding to the intervals (0, SOC1) and (SOC 2, 100%) and a second calculation mode corresponding to the intervals (SOC 1, SOC 2);

the method for acquiring the SOC value of the single battery to be balanced in the battery pack comprises the following steps:

and when the SOC value determined according to the first calculation mode belongs to the intervals (SOC 1 and SOC 2), re-determining the SOC value of the single battery according to the second calculation mode.

2. The method according to claim 1, wherein the determining a target equalization time length of the single battery to be equalized according to the SOC value of the single battery to be equalized and the reference SOC value comprises:

as Δ Q = Δ SOC × C _n Determining an electric quantity difference, wherein delta Q is the electric quantity difference, delta SOC is an SOC difference value between the SOC value of the single battery to be equalized and the reference SOC value, and C _n The available capacity of the single battery to be balanced is obtained;

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

3. The method of claim 1, wherein the first calculation manner is a manner in which the SOC value of the battery cell is calculated last time.

4. The method according to claim 1, wherein the first calculation method is an ampere-hour integral method or an ampere-hour integral combined voltage correction method, and the second calculation method is a calculation method different from the first calculation method in the ampere-hour integral method and the ampere-hour integral combined voltage correction method.

5. The method according to claim 1, wherein the determining a target equalization time length of the single battery to be equalized according to the SOC value of the single battery to be equalized and the reference SOC value comprises:

determining an SOC difference value according to the SOC value of the single battery to be balanced and the reference SOC value;

and determining the target equalization time length of the single battery to be equalized according to the SOC difference value and a preset corresponding relation between the SOC difference value and the target equalization time length.

6. The method according to claim 1, wherein the reference SOC value required for equalization is a minimum value among SOC values of the respective unit cells in the battery pack, a maximum value among SOC values of the respective unit cells in the battery pack, or an average value of the SOC values of the respective unit cells in the battery pack.

7. The method according to claim 6, wherein the controlling the balancing of the single battery to be balanced according to the target balancing time length comprises:

if the reference SOC value is the minimum value of the SOC values of the single batteries, controlling the single batteries to be balanced to discharge according to the target balancing time length; or

If the reference SOC value is the maximum value of the SOC values of the single batteries, controlling the single batteries to be equalized to be charged according to the target equalization time length; or

If the reference SOC value is the average value of the SOC values of the single batteries, controlling the single batteries to discharge when the SOC values of the single batteries to be balanced are larger than the reference SOC value according to the target balancing duration, and controlling the single batteries to charge when the SOC values of the single batteries to be balanced are smaller than the reference SOC value.

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

and determining the single batteries to be balanced from the battery pack according to battery parameter information of each single battery in the battery pack, wherein the battery parameter information comprises at least one of a load voltage value, an internal resistance value, a self-discharge rate value, a voltage change rate, an electric quantity change rate and a time change rate, the voltage change rate is used for representing the change of the load voltage value of each single battery along with the change unit value of the physical quantity, the electric quantity change rate is the electric quantity required to be charged or discharged for enabling the load voltage value of each single battery to change the unit value, and the time change rate is the charging duration or the discharging duration required for enabling the load voltage value of each single battery to change the unit value.

9. A battery equalization system, comprising:

a balancing module, an acquisition module and a control module,

the equalization module is configured to: balancing the single batteries to be balanced according to the target balancing duration;

the control module is used for:

10. The battery equalization system of claim 9, wherein the control module is configured to:

11. The battery equalization system of claim 9, wherein the first calculation method is a method used by the single battery to calculate the SOC value last time.

12. The battery equalization system according to claim 9, wherein the first calculation method is an ampere-hour integral method or an ampere-hour integral combined with a voltage correction method, and the second calculation method is a calculation method different from the first calculation method in the ampere-hour integral method and the ampere-hour integral combined with the voltage correction method.

13. The battery equalization system of claim 9, wherein the control module is configured to:

determining an SOC difference value according to the SOC value of the single battery to be balanced and the reference SOC value; and determining the target equalization time length of the single battery to be equalized according to the SOC difference value and the preset corresponding relation between the SOC difference value and the target equalization time length.

14. The battery equalization system according to claim 9, wherein the reference SOC value required for equalization is a minimum value among the SOC values of the respective unit cells in the battery pack, a maximum value among the SOC values of the respective unit cells in the battery pack, or an average value of the SOC values of the respective unit cells in the battery pack.

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

if the reference SOC value is the minimum value of the SOC values of the single batteries, discharging the single batteries to be balanced according to the target balancing time length; or

If the reference SOC value is the maximum value of the SOC values of the single batteries, controlling the single batteries to be equalized to be charged according to the target equalization duration; or

16. The battery equalization system of any of claims 9-15, wherein the control module is configured to:

and determining the single batteries to be balanced from the battery pack according to battery parameter information of each single battery in the battery pack, wherein the battery parameter information comprises at least one of a load voltage value, an internal resistance value, a self-discharge rate value, a voltage change rate, an electric quantity change rate and a time change rate, the voltage change rate is used for representing the change of the load voltage value of the single battery along with the change unit value of the physical quantity, the electric quantity change rate is the electric quantity required to be charged or discharged for enabling the load voltage value of the single battery to change by the unit value, and the time change rate is the charging duration or the discharging duration required for enabling the load voltage value of the single battery to change by the unit value.

17. The battery equalization system of claim 9, wherein the control module is connected to the acquisition module and the equalization module corresponding to the same cell through a channel, and the control module is configured to control the control module to connect to the corresponding sampling module when it is determined that the cell connected to the control module does not need equalization; alternatively, the first and second electrodes may be,

the control module is further used for multiplexing the channels in a time-sharing manner by the acquisition module and the balancing module when the single battery connected with the control module needs to be balanced.

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

19. The battery equalization system of claim 9, wherein the control module is connected to the acquisition module and the equalization module corresponding to the same cell through two channels.

20. The battery equalization system of claim 19, 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.

21. 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 1-8.

22. An electronic device, comprising:

the computer-readable storage medium recited in claim 21; and

23. A vehicle, characterized in that the vehicle comprises: a battery pack and a battery equalization system as claimed in any of claims 9-20.