CN110015178B

CN110015178B - Battery equalization method, system, vehicle, storage medium and electronic device

Info

Publication number: CN110015178B
Application number: CN201710776106.4A
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: WO2019042357A1; CN110015178A

Abstract

The present disclosure relates to a battery equalization method, a system, a vehicle, a storage medium, and an electronic device, the method comprising: determining performance parameters of each single battery according to battery information of each single battery of the battery pack, which is acquired in a sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and a balancing time period; and when the performance parameter of any single battery in the battery pack meets the adjustment condition of the balance duty ratio corresponding to the performance parameter, adjusting the balance duty ratio of at least one single battery in the battery pack, wherein the single battery comprises the single battery. According to the method and the device, the battery information acquisition and the equalization are carried out in a time-sharing mode, so that the acquired battery information is more accurate, and the equalization effect is better; and in the process of charging or discharging the battery pack, the balance duty ratio is continuously adjusted, so that the acquisition frequency of battery information is controlled, and the safety of the battery pack is ensured.

Description

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

Technical Field

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

Background

A large-capacity battery that provides power energy for an electric vehicle is often referred to as a power battery. The vehicle power battery is generally formed by connecting a plurality of single batteries in series to form a module. With the use of batteries, the difference between the single batteries is gradually enlarged, the consistency between the single batteries is poor, and the capacity of the battery pack is limited due to the short plate effect of the batteries, so that the capacity of the battery pack cannot be fully exerted, and the whole capacity of the battery pack is reduced. On the other hand, the gradual expansion of the difference between the single batteries may cause overcharge of some single batteries, over-discharge of some single batteries, affect the service life of the batteries, damage the batteries, and generate a large amount of heat to cause combustion or explosion of the batteries.

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

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

Disclosure of Invention

An object of the present disclosure is to provide a battery equalization method, system, vehicle, storage medium, and electronic device to improve equalization effect.

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

determining performance parameters of each single battery according to battery information of each single battery of the battery pack, which is acquired in a sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and an equalization time period;

when the performance parameter of any single battery in the battery pack meets the equalization duty ratio adjustment condition corresponding to the performance parameter, the equalization duty ratio of at least one single battery in the battery pack including the single battery is adjusted, the equalization duty ratio is the ratio of the duration of the equalization time period to the duration of the unit period, and the performance parameter comprises at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, rate of change of voltage, rate of change of electrical quantity, and rate of change of time.

In a second aspect, a battery equalization system is provided, including: the device comprises a balancing module, an acquisition module and a control module;

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

the control module is used for determining the performance parameters of each single battery according to the battery information of each single battery of the battery pack, which is acquired in the sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and the balancing time period; when the performance parameter of any single battery in the battery pack meets the equalization duty ratio adjustment condition corresponding to the performance parameter, the equalization duty ratio of at least one single battery in the battery pack including the single battery is adjusted, the equalization duty ratio is the ratio of the duration of the equalization time period to the duration of the unit period, and the performance parameter comprises at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate, and time change rate;

and the balancing module is used for balancing the single batteries needing to be balanced in a balancing time period under the control of the control module.

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

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

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

the computer-readable storage medium of the fourth aspect; and

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

According to the technical scheme, the battery information acquisition and the equalization are carried out in a time-sharing manner, and the battery information acquisition and the equalization are prevented from being carried out simultaneously, so that the acquired battery information is more accurate, and the equalization effect is better; and in the process of charging or discharging the battery pack, the balance duty ratio is continuously adjusted, so that the acquisition frequency of battery information is controlled, and the safety of the battery pack is ensured. On the other hand, after the balancing duty ratio of the single battery needing to be balanced is determined, the duration of the acquisition time period and the duration of the balancing time period are controlled according to the balancing duty ratio under the condition of unit cycle setting, so that the balancing efficiency is improved, and the balancing cost is reduced.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

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

fig. 2 is a schematic diagram of a battery equalization system in which two single batteries share one equalization module according to an embodiment of the present disclosure;

fig. 3 is a schematic diagram of a battery equalization system of another embodiment of the present disclosure;

fig. 4 is a schematic diagram of a battery equalization system in which two single batteries share one equalization module according to another embodiment of the present disclosure;

fig. 5 is a schematic flow chart diagram of a battery equalization method according to an embodiment of the disclosure;

FIG. 6 is a voltage range diagram of an equalization duty cycle adjustment according to an embodiment of the present disclosure;

FIG. 7 is a schematic diagram illustrating the determination of the equalized duty cycle for different cells according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of determining an equalization duty cycle according to an embodiment of the present disclosure;

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

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

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

fig. 12 is a schematic diagram of a flow chart of determining a single battery requiring equalization according to an embodiment of the present disclosure;

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

FIG. 14 is a schematic diagram of an equalization module of an embodiment of the present disclosure;

FIG. 15 is a flow diagram of an equalization process according to an embodiment of the present disclosure;

fig. 16 is a flowchart illustrating acquisition of an equalization duration according to an embodiment of the disclosure.

Detailed Description

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

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

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

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

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

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

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

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

This battery equalizing system includes: a control module 301, an acquisition module 302, an equalization module 303, and a battery pack 304. The battery pack 304 includes a plurality of unit cells connected in series. The control module 301 is connected to the acquisition module 302 and the equalization module 303 corresponding to the same cell via a control channel 305. The control module is used for controlling the connection of the control module and the corresponding sampling module when the single battery connected with the control module is determined not to need balancing; or, the control module is further configured to time-division multiplex the channels 305 according to a unit cycle by the acquisition module and the equalization module when it is determined that the single battery connected to the control module needs to be equalized.

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 that performance parameters such as the SOC, the internal resistance, the self-discharge rate, and the like of the single battery can be obtained.

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

Therefore, in the embodiment of the disclosure, the acquisition module and the balancing module share the same control channel, the control module controls the acquisition module and the balancing module, and the control channel is multiplexed in time according to a unit period, so that the influence of balancing current on the accuracy of battery information acquisition is avoided when the battery information acquisition and the balancing are performed simultaneously; on the other hand, compared with the embodiment shown in fig. 1, the requirement for the number of channels of the control module chip is reduced, and the hardware cost can be saved.

In one embodiment, a switch K is disposed in a control channel shared by the acquisition module and the equalization module, and the control module 301 is connected to the switch K and is connected to the acquisition module 302 or the equalization module 303 in a time-sharing manner by controlling the switch K. When the switch K is connected 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.

From this, through with the switch setting between control module and collection module, balanced module, control module can reach the effect of gathering with balanced through regulating switch's state to not sampling when can realizing the equilibrium, unbalanced effect during the sampling, thereby balanced electric current can not influence battery voltage, thereby precision when having improved battery voltage sampling.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

In the embodiment of the disclosure, the unit cycle is divided into the acquisition time period and the equalization time period, and the ratio of the duration of the equalization time period to the duration of the unit cycle is the equalization duty ratio. According to the battery balancing method, after the balancing duty ratio of the single battery to be balanced which needs to be balanced is determined, the balancing of the single battery to be balanced is controlled according to the determined balancing duty ratio, so that the balancing efficiency is improved, and the balancing cost is saved.

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

in step S51, performance parameters of each single battery are determined according to battery information of each single battery of the battery pack, which is acquired in a sampling period of a unit cycle. The unit cycle includes the sampling period and the equalization period.

In step S52, when the performance parameter of any single battery in the battery pack satisfies the adjustment condition of the balancing duty ratio corresponding to the performance parameter, the balancing duty ratio of at least one single battery including the single battery in the battery pack is adjusted.

The equalization duty ratio is a ratio of a duration of the equalization period to a duration of the unit period. The performance parameters include at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, rate of change of voltage, rate of change of electrical quantity, and rate of change of time.

In the embodiment of the present disclosure, as described above, the acquisition module and the equalization module are turned on in time division according to the unit cycle, and the battery information acquisition is performed only in the sampling period. The duration of the sampling period and the duration of the equalization period of the unit cycle can be determined according to the equalization duty ratio of each single battery. The equalizing duty ratio of each single battery in the battery pack can be the same or different. The balancing duty ratio of each single battery can be a preset value or calculated according to battery information. The equalization duty ratio is calculated from the battery information, which will be described in the subsequent embodiments.

When the battery pack is in a charging or discharging process, safety needs to be guaranteed, and therefore the control over the frequency of battery information acquisition is achieved by adjusting the balanced duty ratio in the embodiment of the disclosure.

In an embodiment of the present disclosure, when the battery pack is in a charging state, and a value of a performance parameter of any single battery is greater than or equal to a first preset threshold corresponding to the performance parameter, the equalization duty cycle of at least one single battery including the single battery in the battery pack is adjusted to be reduced; or,

and when the battery pack is in a discharging state and the value of the performance parameter of any single battery is smaller than a second preset threshold corresponding to the performance parameter, reducing and adjusting the balance duty ratio of at least one single battery including the single battery in the battery pack.

In the embodiment of the present disclosure, the balancing duty ratio is adjusted, the balancing duty ratio of the single battery whose performance parameter reaches the adjustment threshold value may be adjusted, and the balancing duty ratios of all the single batteries may also be adjusted.

The performance parameter may be voltage, then: in the charging process of the single batteries, when the voltage of any single battery reaches high voltage and is alarmed, in order to ensure the safety of the single battery and prevent the single battery from generating overcharge phenomenon, the real-time monitoring of the single battery needs to be strengthened, the balanced duty ratio of a system is reduced, the battery information acquisition frequency of the single battery is increased, and the state of the single battery is monitored in real time. In the discharging process of the single batteries, when the voltage of any single battery reaches low voltage alarm, in order to ensure the safety of the single batteries and prevent the over-discharge phenomenon of the single batteries, the real-time monitoring of the single batteries needs to be strengthened, the balanced duty ratio of the system is reduced, the battery information acquisition frequency of the single batteries is increased, and the battery state is monitored in real time.

In the charging process of the battery pack, the first preset threshold is a first preset high-voltage threshold or a second preset high-voltage threshold, and the second preset high-voltage threshold is larger than the first preset high-voltage threshold. The step S52 includes:

when the battery pack is in a charging state, the voltage value of any single battery is higher than the first preset high-voltage threshold value, and the balance duty ratio of at least one single battery comprising the single battery is subjected to reduced adjustment;

when the battery pack is in a charging state, the voltage value of any single battery is higher than the second preset high-voltage threshold value, and the balance duty ratio of at least one single battery including the single battery is adjusted to be 0.

In the discharging process of the battery pack, the second preset threshold is a first preset low-voltage threshold or a second preset low-voltage threshold, and the second preset low-voltage threshold is smaller than the first preset low-voltage threshold. The step S52 includes:

when the battery pack is in a discharging state and the voltage value of any single battery is lower than the first preset low-voltage threshold value, reducing and adjusting the balance duty ratio of at least one single battery comprising the single battery;

when the battery pack is in a discharging state and the voltage value of any single battery is lower than the second preset low-voltage threshold value, the balance duty ratio of at least one single battery including the single battery is adjusted to be 0.

Referring to fig. 6, the adjustment of the battery equalization duty ratio is classified into different levels according to the degree of danger of the battery voltage. Vh1 is a first preset high-voltage threshold (general high-voltage alarm value), vh2 is a second preset high-voltage threshold (serious high-voltage alarm value), vl1 is a first preset low-voltage threshold (general low-voltage alarm value), vl2 is a second preset low-voltage threshold (serious low-voltage alarm value), then:

(1) When the voltage V epsilon of any single battery is (Vl 1, vh 1), the balanced duty ratio of the single battery is tau 1;

(2) When any single battery voltage V belongs to (Vl 2, vl 1) or V belongs to [ Vh1, vh 2), adjusting the balance duty ratio of the single battery to be tau 2;

(3) When the voltage V of any single battery is less than or equal to Vl2 or V is more than or equal to Vh2, the balanced duty ratio of the single battery is adjusted to tau 3. Wherein tau is more than or equal to 0 and more than tau 3 and more than tau 2 and more than tau 1 and less than 1.

In an embodiment of the present disclosure, the step S52 includes:

when the difference between the value of the performance parameter of any single battery and the reference value of the performance parameter is larger than the initial difference, the equalizing duty ratio of at least one single battery comprising the single battery is adjusted in an increasing way;

when the difference between the value of the performance parameter of any one of the single batteries and the reference value of the performance parameter becomes smaller than the initial difference, a reduced adjustment is made to the equalization duty ratio of at least one of the single batteries including the single battery.

The reference value of the performance parameter may be a maximum value, a minimum value, or an average value of the performance parameter of each unit cell. In one embodiment, taking the target performance parameter as the voltage as an example:

(1) When the voltage difference value delta V between the voltage of any single battery and the voltage reference value is not changed, keeping the balance duty ratio of each single battery unchanged;

(2) When the voltage difference value delta V is increased, in order to ensure that the balance task is completed within the balance total time required by the system, the balance duty ratio is increased to be k1 times (k 1 is more than 1) of the original balance duty ratio, so that the balance speed is accelerated. The increasing of the balancing duty ratio here may be increasing of the balancing duty ratio of all the unit cells.

(3) When the voltage difference value Δ V becomes smaller, the equalization duty ratio of the system can be reduced to k2 times (0-k 2-n 1) of the original duty ratio, and the frequency of battery information acquisition is increased, so as to increase the acquisition frequency of the battery information. The reducing of the equalizing duty ratio here may be reducing of the equalizing duty ratio of all the unit cells.

Therefore, the adjustment of the balance duty ratio can be realized according to the change condition of the performance parameters of the single battery, the collection frequency of battery information is controlled, and the safety of the single battery is improved.

Referring to fig. 7, in an embodiment of the present disclosure, the method further includes:

in step S71, the cells in the battery pack that need to be equalized are determined according to the battery information of each cell.

In step S72, for the single battery cell requiring equalization, an equalization duty ratio of the single battery cell requiring equalization is determined according to battery information of each single battery cell.

In step S73, for the unit cells that do not require equalization, the equalization duty ratio thereof is set to a preset value.

In the embodiment of the present disclosure, initially, for example, when the battery pack starts to be charged or discharged, when the acquisition is performed for the first time, the duration of the acquisition period and the duration of the equalization period in the unit cycle may be determined according to the preset value of the equalization duty ratio. The preset value can be an initial balancing duty ratio or the balancing duty ratio of each single battery when the battery pack stops working last time. In one embodiment, the initial equalization duty cycle may be set to 0, i.e., acquisition only.

After the balancing duty ratio of the single battery needing to be balanced is determined, the time length of the acquisition time period and the time length of the balancing time period of the unit cycle of the single battery needing to be balanced are determined according to the newly determined balancing duty ratio. For the single batteries which do not need to be balanced, the time length of the acquisition time period and the time length of the balancing time period of the unit cycle can be determined according to the preset value of the balancing duty ratio, the battery information is acquired in the acquisition time period, but the balancing is not performed in the balancing time period. For the single battery needing to be equalized, the equalization duty ratio can be determined according to the method shown in fig. 8:

in step S81, a value of any one of the following performance parameters of each unit cell is acquired from the battery information of each unit cell: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate and time change rate;

in step S82, a reference value of the target performance parameter is determined according to a value of the target performance parameter of each unit cell, where the target performance parameter is any one of the following performance parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate and time change rate;

in step S83, determining an equalization duty ratio of the single battery cell requiring equalization according to the reference value of the target performance parameter and the value of the target performance parameter of the single battery cell requiring equalization.

In an embodiment of the present disclosure, the balancing duty ratio of the single battery to be balanced is determined according to a difference between a value of a target performance parameter of the single battery to be balanced and a reference value of the target performance parameter, and a corresponding relationship between a preset difference between the target performance parameter and the reference value of the target performance parameter and the balancing duty ratio. For example, when the target performance parameter is voltage, different voltage difference values have a corresponding relationship with the balancing duty ratio, and according to the corresponding relationship, the balancing duty ratio of the single battery needing to be balanced can be obtained according to the voltage of the single battery needing to be balanced. The reference value of the target performance parameter may be a maximum value, a minimum value, or an average value of the target performance parameters of the respective unit cells.

In the following embodiments, another manner of obtaining the equalization duty ratio is described by taking target performance parameters of voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate, and time change rate as examples.

When the target performance parameter is voltage, referring to fig. 9, the step of determining the balancing duty ratio of the single battery to be balanced according to the voltage value of the single battery to be balanced and the reference voltage value includes:

in step S91, the cell in the battery pack having the smallest difference between the voltage value and the reference voltage value is determined as the reference cell.

In step S92, a first SOC value corresponding to the reference voltage value is determined according to the reference voltage value and the open circuit voltage OCV-remaining capacity SOC curve of the reference battery.

In step S93, a second SOC value corresponding to the voltage value of the cell requiring equalization is determined according to the voltage value of the cell requiring equalization and the OCV-SOC curve corresponding to the cell requiring equalization.

In step S94, an equalization duty ratio of the unit battery to be equalized is determined according to the first SOC value and the second SOC value.

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

The step S92 includes:

determining a reference OCV value of the reference battery according to the reference voltage value and the internal resistance value of the reference battery; then, an SOC value corresponding to the reference OCV value is determined as a first SOC value based on the reference OCV value and an OCV-SOC curve of the reference battery.

The step S93 includes:

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

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

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

OCV＝V _L +I×R (1)

wherein, V _L The load voltage value collected by the collecting module in the collecting time period; i is the discharging current or the charging current collected by the collecting module in the collecting time period; and R is the internal resistance value of the single battery.

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

And after the open-circuit voltage of the single battery is obtained, the SOC value corresponding to the single battery can be obtained according to the OCV-SOC curve of the single battery.

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

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

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

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

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

ΔQ＝ΔSOC×C _n (2)

where Δ Q is the difference in electrical quantities, Δ SOC is the difference in SOC between the first and second SOC values, C _n The available capacity of the single battery needing to be balanced.

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

τ＝(ΔQ/I)/t (3)

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

In one embodiment, when the target performance parameters are: when the SOC value is obtained, determining the balance duty ratio according to the reference value of the target performance parameter and the value of the target performance parameter of the single battery needing to be balanced, wherein the method comprises the following steps:

as Δ Q = Δ SOC × C _n Determining an 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 needing to be balanced and a reference value of the SOC, and C _n The available capacity of the single batteries needing to be balanced;

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

It should be understood that when the battery information of each unit battery is collected, the SOC value of each unit battery may be obtained according to an ampere-hour integration method or an open-circuit voltage method. In one embodiment, the equalization duty ratio can be determined by combining the voltage and the SOC, and when the number of SOC values belonging to a first preset interval in the SOC values of the individual batteries in the battery pack is greater than or equal to the number of SOC values not belonging to the first preset interval, the equalization duty ratio of the individual batteries needing equalization is determined for the SOC mode according to the target performance parameter;

when the number of the SOC values belonging to the first preset interval in the SOC values of the single batteries in the battery pack is less than the number of the SOC values not belonging to the first preset interval, determining the balance duty ratio of the single batteries needing to be balanced in a voltage mode according to the target performance parameter.

Or determining a reference SOC value according to the SOC values of the single batteries in the battery pack; when the reference SOC value belongs to a second preset interval, determining the balance duty ratio of the single battery needing to be balanced in a mode of taking the target performance parameter as SOC; and when the reference SOC value does not belong to the second preset interval, determining the balance duty ratio of the single battery needing to be balanced in a mode of taking the target performance parameter as voltage.

In one embodiment, when the target performance parameter is the internal resistance, determining the balancing duty ratio according to the reference value of the target performance parameter and the value of the target performance parameter of the single battery needing balancing, including:

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

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

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

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

It should be understood that the steps of determining the first SOC value, determining the second SOC value, and determining the equalizing duty ratio according to the first SOC value and the second SOC value may be performed in the above embodiment in which the target performance parameter is a voltage, and thus, the description thereof is omitted.

In one embodiment, when the target performance parameter is the self-discharge rate, determining the equalization duty ratio according to the reference value of the target performance parameter and the value of the target performance parameter of the single battery needing equalization includes:

determining the single battery with the minimum difference between the self-discharge rate value and the reference value of the self-discharge rate value in the battery pack as a reference battery;

acquiring the electric quantity difference between the single battery to be balanced and a reference battery according to the self-discharge rate value and the reference self-discharge rate value of the single battery to be balanced;

and determining the balance duty ratio according to the preset balance current, the preset balance time and the electric quantity difference.

In one embodiment, the difference in charge is: Δ Q = Δ η × t, where Δ η is a difference between a self-discharge rate value of the cell requiring equalization and a self-discharge rate value of the reference battery, and t is an interval duration from the last equalization end of the cell requiring equalization.

And (4) determining the balance duty ratio according to the preset balance current, the preset balance time and the electric quantity difference, which is shown in the formula (3).

In one embodiment, the self-discharge rate value of each single battery in the battery pack can be obtained according to the following method:

after the battery pack is powered off, determining a first moment when each single battery in the battery pack reaches a stable state and a first open-circuit voltage value corresponding to the single battery at the first moment;

when the battery pack is electrified again, determining a second moment when each single battery in the battery pack is electrified and a second open-circuit voltage value of each single battery at the second moment;

and determining the ratio of the voltage difference value to the time length to be the self-discharge rate value of the single battery according to the voltage difference value between the first open-circuit voltage value and the second open-circuit voltage value corresponding to the single battery and the time length between the first time and the second time corresponding to the single battery.

In one embodiment, when the target performance parameter is a voltage change rate, determining an equalization duty ratio according to a reference value of the target performance parameter and a value of the target performance parameter of the single battery to be equalized includes:

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

when the initial end voltage of the single battery needing to be balanced is different from the initial end voltage of the reference battery, determining the balancing duty ratio of the single battery needing to be balanced according to the initial end voltage of the single battery needing to be balanced and the initial end voltage of the reference battery;

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

In one embodiment, the voltage change rate value of each single battery cell can be obtained according to the following method:

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

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

In another embodiment, the voltage change rate value of each single battery can be obtained according to the following method:

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

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

It should be understood that, the method for determining the balancing duty ratio of the single battery to be balanced according to the initial terminal voltage of the single battery to be balanced and the initial terminal voltage of the reference battery, or the method for determining the balancing duty ratio of the single battery to be balanced according to the final terminal voltage of the single battery to be balanced and the final terminal voltage of the reference battery is the same as the method for determining the balancing duty ratio according to the voltage and the reference voltage value of the single battery to be balanced in the embodiment where the target performance parameter is voltage, and will not be described herein again.

In one embodiment, when the target performance parameter is the electric quantity change rate, determining the equalization duty ratio according to the reference value of the target performance parameter and the value of the target performance parameter of the single battery needing equalization, including:

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

when the initial end voltage of the single battery needing to be balanced is the same as the initial end voltage of the reference battery, determining the balancing duty ratio of the single battery needing to be balanced according to the electric quantity required to be charged when the voltage of the single battery needing to be balanced rises by one unit voltage from the initial end voltage and the electric quantity required to be charged when the voltage of the reference battery rises by one unit voltage from the initial end voltage, or determining the balancing duty ratio of the single battery needing to be balanced according to the electric quantity reduced when the voltage of the single battery needing to be balanced drops by one unit voltage from the initial end voltage and the electric quantity reduced when the voltage of the reference battery drops by one unit voltage from the initial end voltage.

In one embodiment, the charge rate value of each single battery can be obtained according to the following method:

in the charging process of the battery pack, acquiring the electric quantity required to be charged when the voltage of each single battery rises by one unit voltage from the initial terminal voltage;

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

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

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

In one embodiment, the method for determining the balancing duty ratio of the single battery to be balanced according to the initial terminal voltage of the single battery to be balanced and the initial terminal voltage of the reference battery is the same as the method for determining the balancing duty ratio according to the voltage of the single battery to be balanced and the reference voltage value in the embodiment where the target performance parameter is the voltage, and details are not repeated here.

In one embodiment, when the initial terminal voltage of the unit cell requiring equalization is the same as the initial terminal voltage of the reference cell:

determining the difference between the electric quantity of the single battery needing to be balanced and the electric quantity of the reference battery according to the electric quantity required to be charged when the voltage of the single battery needing to be balanced is increased by one unit voltage from the initial end voltage and the electric quantity required to be charged when the voltage of the reference battery is increased by one unit voltage from the initial end voltage or according to the electric quantity reduced when the voltage of the single battery needing to be balanced is reduced by one unit voltage from the initial end voltage and the electric quantity reduced when the voltage of the reference battery is reduced by one unit voltage from the initial end voltage;

and determining the balance duty ratio of the single battery needing to be balanced according to the electric quantity difference, the preset balance time length and the preset balance current. In one embodiment, referring to equation (3) above, an equalization duty cycle may be determined.

In one embodiment, when the target performance parameter is a time change rate, determining an equalization duty ratio according to a reference value of the target performance parameter and a value of the target performance parameter of the single battery needing equalization includes:

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

when the initial terminal voltage of the single battery needing to be balanced is the same as the initial terminal voltage of the reference battery, determining the balancing duty ratio of the single battery needing to be balanced according to the charging time of the single battery needing to be balanced and the charging time of the reference battery, or according to the discharging time of the single battery needing to be balanced and the discharging time of the reference battery.

In one embodiment, obtaining a time rate of change value of each battery cell comprises:

in the charging process of the battery pack, acquiring the charging time required by the voltage of each single battery to rise by one unit voltage from the initial terminal voltage;

for each single battery in the battery pack, determining the time change rate value of the single battery as the ratio of the required charging time of the single battery to the value of the unit voltage; or,

in the discharging process of the battery pack, obtaining the discharging time required by the voltage of each single battery to be reduced by one unit voltage from the initial terminal voltage;

and for each single battery in the battery pack, determining the time change rate value of the single battery as the ratio of the required discharge time of the single battery to the value of the unit voltage.

In one embodiment, when the initial terminal voltage of the single battery needing to be equalized is the same as the initial terminal voltage of the reference battery, determining the equalization duty ratio of the single battery needing to be equalized comprises the following steps:

determining the electric quantity difference between the single battery needing to be equalized and the reference battery according to the charging time required by the voltage of the single battery needing to be equalized to rise by one unit voltage from the initial terminal voltage, the charging time required by the voltage of the reference battery to rise by one unit voltage from the initial terminal voltage and the current integral value, or determining the electric quantity difference between the single battery needing to be equalized and the reference battery according to the discharging time required by the voltage of the single battery needing to be equalized to fall by one unit voltage from the initial terminal voltage, the discharging time required by the voltage of the reference battery to fall by one unit voltage from the initial terminal voltage and the current integral value;

and determining the balance duty ratio of the single battery needing to be balanced according to the electric quantity difference, the preset balance time and the preset balance current. In one embodiment, referring to equation (3) above, an equalization duty cycle may be determined.

In an embodiment of the present disclosure, for a single battery that needs to be balanced, in addition to adjusting the balancing duty ratio according to the above-described embodiment, the adjusting of the balancing duty ratio further includes:

in the balancing process of the single batteries needing to be balanced, when the difference value between the value of the target performance parameter of the single battery needing to be balanced and the reference value of the target performance parameter is larger than the difference value at the beginning of balancing, performing increased adjustment on the balancing duty ratio of the single battery needing to be balanced;

in the balancing process of the single battery needing to be balanced, when the difference value between the target performance parameter value of the single battery needing to be balanced and the reference value of the target performance parameter is smaller than the difference value at the beginning of balancing, the balancing duty ratio of the single battery needing to be balanced is adjusted in a reducing mode.

Therefore, for the single batteries needing to be balanced, the balancing duty ratio can be adjusted according to the value of the target performance parameter in the balancing process except for the balancing duty ratio adjusting mode, and the balancing safety and efficiency are guaranteed.

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

Referring to fig. 12, in an embodiment of the present disclosure, in the step S71, the unit cells requiring equalization may be determined by:

in step S121, a difference between the performance parameter of the at least one unit cell and a reference value of the performance parameter is determined.

In step S122, the cell in which the difference between the performance parameter and the reference value of the performance parameter is greater than or equal to the equalization start threshold value in the at least one cell is determined as the cell requiring equalization that needs equalization.

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

As described above, when the performance parameter is voltage, the above-described step of determining the unit cells requiring equalization is described with reference to fig. 13:

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

In an embodiment of the present disclosure, a minimum voltage value among voltage values of the respective unit cells in the battery pack may be determined as a reference voltage value; or, determining the maximum voltage value in the voltage values of the single batteries in the battery pack as a reference voltage value; or, determining the average value of the voltage values of the single batteries in the battery pack as the reference voltage value.

In step S132, the cell of which the voltage difference between the voltage value and the reference voltage value is greater than or equal to the balancing start threshold value in the at least one cell is determined as the cell requiring balancing.

When the reference voltage value is the minimum value among the voltage values of the respective unit cells, step S71 includes:

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

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

When the reference voltage value is the maximum value among the voltage values of the respective unit cells, step S131 includes:

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

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

When the reference voltage value is an average value of the voltage values of the respective unit cells, step S131 includes:

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

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

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

TABLE 1

Therefore, when the equalization judgment is carried out by adopting the performance parameters of different batteries, the judgment is carried out according to the corresponding mode in the table 1, and the single batteries needing equalization in the battery pack are determined by combining the judgment flow when the performance parameters are voltages.

It should be understood that if there is no single battery that needs to be equalized, the equalization determination is continued according to the information acquired in the next acquisition period. When the single batteries needing to be balanced are determined to be absent according to the information acquired in the acquisition time period, the control module does not act in the balancing time period, so that the balancing module corresponding to any battery is not started.

Equalization process

Fig. 14 is a schematic diagram of an equalizing module according to an embodiment of the disclosure. And controlling the single batteries needing to be balanced in the balancing time period of the unit cycle, wherein the balancing needs to be carried out in combination with the balancing judgment. In the step of equalization determination (as described in steps S121 and S122 above), it is determined whether the equalization manner of the single battery needing equalization is passive equalization (i.e., discharging the single battery needing equalization) or active equalization (i.e., charging the single battery needing equalization), and the corresponding equalization module is turned on.

Referring to fig. 14, for passive equalization, the equalization module includes: and each single battery corresponds to one equalizing module, namely two ends of each single battery are connected with one resistor in parallel.

For the single battery needing to be passively balanced and needing to be balanced, in the balancing time period of a unit cycle, the control module controls the conduction of a parallel loop between the single battery needing to be balanced and the corresponding resistor of the single battery, so that the passive balancing of the single battery is executed. Referring to fig. 14, the control module controls the switch module 812 to be turned on, so as to achieve the conduction of the parallel loop between the single battery needing 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 thermistor with a positive temperature coefficient, which may change with the temperature, 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. 14, 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 needing active equalization and needing equalization, the control module controls the charging branch 94 corresponding to the single battery needing equalization 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 needing to be balanced, and the electricity of the single battery needing to be balanced is increased.

Referring to fig. 14, 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 in series with the 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 batteries needing to be balanced.

Referring to fig. 14, the control module may perform active equalization on the single battery requiring equalization by controlling the switch 96 corresponding to the single battery requiring equalization to be turned on, so that the charging branch corresponding to the single battery requiring equalization is turned on.

In other embodiments, in addition to charging the single batteries by the generator as shown in fig. 14, 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 needing to be balanced shown in fig. 14, the single battery needing to be balanced may be connected in parallel with the starting battery of the entire vehicle, and the electric quantity discharged by the single battery needing to be balanced is charged into the starting battery, so that the single battery needing to be balanced is balanced, and energy waste is effectively avoided.

As described above, in the embodiment of the present disclosure, a plurality of single batteries may share one balancing module, and when at least two single batteries among a plurality of single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected to each single battery among the at least two single batteries needing to be balanced in a balancing period of a unit cycle, and balancing is performed separately.

In an embodiment of the present disclosure, when balancing the single battery needing balancing according to the balancing duty ratio, the accumulated balancing time of the single battery needing balancing reaches the preset balancing time. Since the duration of a single unit cycle is limited, the equalization of a cell requiring equalization may be performed during one or more equalization periods of the unit cycle.

Referring to fig. 15, in step S151, the control module controls the control channels of the balancing required unit cells to be balanced, and balances the balancing required unit cells in the balancing period.

In step S152, when a single balancing time period ends, the control module determines whether the balancing of all the single batteries needing to be balanced is completed, that is, whether the accumulated balancing time length of all the single batteries needing to be balanced reaches the corresponding preset balancing time length. If the balancing time of all the single batteries needing to be balanced reaches the requirement, executing step S154; if the equalization duration of any single battery needing equalization does not meet the requirement, step S153 is executed.

When the single batteries needing to be balanced are balanced in a balancing time period, when the accumulated balancing time of any single battery needing to be balanced reaches the corresponding preset balancing time, the balancing of the single battery needing to be balanced is controlled to stop.

In step S153, when a single unit cycle is ended, if the accumulated equalization duration of any single battery that needs equalization does not reach the preset equalization duration corresponding to the accumulated equalization duration, after the sampling duration of the next unit cycle is ended, in the equalization duration, the equalization of the single battery that does not reach the equalization duration is continuously controlled, and step S152 is executed.

In step S154, a new round of equalization determination is started, and according to the battery information acquired in the acquisition time period, the single batteries needing equalization are determined and the equalization duty ratios of the single batteries needing equalization are determined.

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

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

Referring to fig. 16, in step S161, target parameter information of the unit cells requiring equalization is acquired. The target parameter comprises any one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, rate of change of voltage, rate of change of electrical quantity, and rate of change of time.

In step S162, a historical balancing duration and historical parameter information of the single battery cell to be balanced are obtained, where the historical parameter information is historical information of the target parameter information.

In step S163, an equalization time period required for the current equalization of the single battery to be equalized is determined according to the target parameter information, the historical equalization time period, and the historical parameter information. The equalization duration is used as the preset equalization duration.

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

wherein, t _k The equalization duration is the equalization time; t is t _k-1 The historical balancing time of the last balancing of the single battery needing balancing is prolonged; delta S _k The difference value between the target parameter of the single battery to be balanced and the reference value of the target parameter is the current moment; delta S _k-1 The difference value between the target parameter of the single battery to be balanced and the reference value of the target parameter is the last balancing moment; c _k The current available capacity of the single batteries needing to be balanced at the current moment; c _k-1 And the historical available capacity of the single batteries needing to be balanced at the last balancing moment.

Correspondingly, the embodiment of the present disclosure further provides a battery equalization system, including: the device comprises a balancing module, an acquisition module and a control module;

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

In one embodiment, the control module is configured to, when the battery pack is in a charging state and a value of a performance parameter of any single battery is greater than or equal to a first preset threshold corresponding to the performance parameter, perform adjustment for reducing a balancing duty ratio of at least one single battery including the single battery in the battery pack; or,

when the battery pack is in a discharging state, when the value of the performance parameter of any single battery is smaller than a second preset threshold value corresponding to the performance parameter, the balance duty ratio of at least one single battery including the single battery in the battery pack is adjusted in a reducing mode.

In one embodiment, the performance parameter is voltage, the first preset threshold is a first preset high voltage threshold or a second preset high voltage threshold, and the second preset high voltage threshold is greater than the first preset high voltage threshold;

the control module is used for reducing and adjusting the balance duty ratio of at least one single battery including the single battery when the voltage value of any single battery is higher than the first preset high-voltage threshold value when the battery pack is in a charging state;

In one embodiment, the performance parameter is a voltage, the second preset threshold is a first preset low voltage threshold or a second preset low voltage threshold, and the second preset low voltage threshold is smaller than the first preset low voltage threshold;

the control module is used for reducing and adjusting the balance duty ratio of at least one single battery including the single battery when the battery pack is in a discharging state and the voltage value of any single battery is lower than the first preset low-voltage threshold value;

In one embodiment, the control module is configured to, when a difference between a value of a performance parameter of any one of the single batteries and a reference value of the performance parameter becomes larger than an initial difference, perform increased adjustment on an equalization duty ratio of at least one of the single batteries including the single battery;

when the difference between the value of the performance parameter of any single battery and the reference value of the performance parameter becomes smaller than the initial difference, the equalization duty ratio of at least one single battery including the single battery is subjected to reduced adjustment.

In one embodiment, the control module is further configured to determine, according to battery information of each single battery, a single battery in the battery pack that needs to be balanced; for the single batteries needing to be balanced, determining the balancing duty ratio of the single batteries needing to be balanced according to the battery information of each single battery; and setting the balance duty ratio of the single batteries which do not need to be balanced as a preset value.

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

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

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

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

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

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

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

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

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

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

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

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

Claims

1. A method of battery equalization, comprising:

determining performance parameters of each single battery according to battery information of each single battery of the battery pack, which is acquired in a sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and a balancing time period;

when the performance parameter of any single battery in the battery pack meets the equalization duty ratio adjustment condition corresponding to the performance parameter, adjusting the equalization duty ratio of at least one single battery in the battery pack, wherein the equalization duty ratio is the ratio of the duration of the equalization time period to the duration of the unit period, and the performance parameter comprises at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate, and time change rate.

2. The method according to claim 1, wherein when the performance parameter of any single battery in the battery pack satisfies the adjustment condition of the balancing duty ratio corresponding to the performance parameter, adjusting the balancing duty ratio of at least one single battery in the battery pack, which includes the single battery, includes:

when the battery pack is in a charging state and the value of the performance parameter of any single battery is greater than or equal to a first preset threshold corresponding to the performance parameter, carrying out reduced adjustment on the balanced duty ratio of at least one single battery comprising the single battery in the battery pack; or,

when the battery pack is in a discharging state and the value of the performance parameter of any single battery is smaller than a second preset threshold corresponding to the performance parameter, the balance duty ratio of at least one single battery including the single battery in the battery pack is adjusted in a reducing mode.

3. The method of claim 2, wherein the performance parameter is voltage, the first predetermined threshold is a first predetermined high voltage threshold or a second predetermined high voltage threshold, the second predetermined high voltage threshold is greater than the first predetermined high voltage threshold;

the adjusting the balance duty ratio of at least one single battery including the single battery in the battery pack comprises:

when the battery pack is in a charging state, the voltage value of any single battery is higher than the first preset high-voltage threshold value, and the balance duty ratio of at least one single battery comprising the single battery is subjected to reduction adjustment;

4. The method of claim 2, wherein the performance parameter is voltage, the second predetermined threshold is a first predetermined low voltage threshold or a second predetermined low voltage threshold, and the second predetermined low voltage threshold is less than the first predetermined low voltage threshold;

the adjusting of the balanced duty ratio of each single battery in the battery pack comprises the following steps:

5. The method according to claim 1, wherein when the performance parameter of any single battery in the battery pack satisfies the adjustment condition of the balancing duty ratio corresponding to the performance parameter, adjusting the balancing duty ratio of each single battery in the battery pack includes:

when the difference value between the performance parameter value of any single battery and the reference value of the performance parameter is larger than the initial difference value, the equalizing duty ratio of at least one single battery comprising the single battery is adjusted in an increasing way;

when the difference between the value of the performance parameter of any one of the single batteries and the reference value of the performance parameter becomes smaller than the initial difference, the equalization duty ratio of at least one single battery including the single battery is subjected to a decreasing adjustment.

6. The method according to any one of claims 1 to 5, wherein when a performance parameter of any single battery in a battery pack satisfies an equalization duty ratio adjustment condition corresponding to the performance parameter, the method adjusts an equalization duty ratio of at least one single battery in the battery pack, which includes the single battery, and further includes:

determining the single batteries needing to be balanced in the battery pack according to the battery information of each single battery;

for the single batteries needing to be balanced, determining the balancing duty ratio of the single batteries needing to be balanced according to the battery information of each single battery;

and setting the balance duty ratio of the single batteries which do not need to be balanced as a preset value.

7. The method of claim 6, wherein the battery information comprises: at least one of a voltage value, a current value, and a temperature value;

the determining the balancing duty ratio of the single battery needing to be balanced according to the battery information of each single battery comprises the following steps:

according to the battery information of each single battery, acquiring the value of any one of the following performance parameters of each single battery: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate and time change rate;

determining a reference value of a target performance parameter according to a value of the target performance parameter of each single battery, wherein the target performance parameter is any one of the following performance parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate and time change rate;

and determining the balancing duty ratio of the single battery needing to be balanced according to the reference value of the target performance parameter and the value of the target performance parameter of the single battery needing to be balanced.

8. The method of claim 7, further comprising:

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

9. The method of claim 7, wherein the target performance parameter is: a voltage;

the determining the balancing duty ratio of the single battery needing balancing according to the reference value of the target performance parameter and the value of the target performance parameter of the single battery needing balancing comprises the following steps:

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

10. The method of claim 7, wherein the target performance parameter is: a voltage;

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

determining a first SOC value corresponding to a reference voltage value according to the reference value of the voltage and the OCV-SOC curve of the reference battery;

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

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

11. The method according to claim 10, wherein said determining a first SOC-value corresponding to said reference voltage value from said reference value of voltage and said OCV-SOC curve of said reference battery comprises:

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

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

the determining a second SOC value corresponding to the voltage value of the single battery to be balanced according to the voltage value of the single battery to be balanced and the OCV-SOC curve corresponding to the single battery to be balanced includes:

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

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

12. The method of claim 11, wherein the step of determining the balancing duty cycle of the single battery needing balancing according to the first SOC value and the second SOC value comprises:

as Δ Q = Δ SOC × C _n Determining a difference in electrical quantities, where Δ Q is the difference in electrical quantities, Δ SOC is a difference in SOC between the first and second SOC values, and C _n The available capacity of the single battery needing to be balanced is obtained;

13. The method according to claim 6, wherein the determining the single battery needing equalization in the battery pack needs equalization comprises:

acquiring performance parameters of each single battery according to battery information of each single battery of the battery pack acquired in a sampling time period of a unit cycle;

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

14. A battery equalization system, comprising: the device comprises a balancing module, an acquisition module and a control module;

the control module is used for determining the performance parameters of each single battery according to the battery information of each single battery of the battery pack, which is acquired in the sampling time period of a unit cycle, wherein the unit cycle comprises the sampling time period and the balancing time period; when the performance parameter of any single battery in the battery pack meets the equalization duty ratio adjustment condition corresponding to the performance parameter, adjusting the equalization duty ratio of at least one single battery in the battery pack, wherein the equalization duty ratio is the ratio of the duration of the equalization time period to the duration of the unit period, and the performance parameter comprises at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, electric quantity change rate and time change rate;

15. The system according to claim 14, wherein the control module is configured to, when the battery pack is in a charging state and a value of a performance parameter of any one of the single batteries is greater than or equal to a first preset threshold corresponding to the performance parameter, perform adjustment to reduce an equalization duty ratio of at least one of the single batteries in the battery pack that includes the single battery; or,

when the battery pack is in a discharging state, when the value of the performance parameter of any single battery is smaller than a second preset threshold corresponding to the performance parameter, the balance duty ratio of at least one single battery including the single battery in the battery pack is adjusted in a reducing mode.

16. The system of claim 15, wherein the performance parameter is voltage, the first predetermined threshold is a first predetermined high voltage threshold or a second predetermined high voltage threshold, the second predetermined high voltage threshold is greater than the first predetermined high voltage threshold;

17. The system of claim 15, wherein the performance parameter is voltage, the second predetermined threshold is a first predetermined low voltage threshold or a second predetermined low voltage threshold, and the second predetermined low voltage threshold is less than the first predetermined low voltage threshold;

18. The system of claim 14, wherein the control module is configured to perform an increasing adjustment on the equalization duty cycle of at least one unit cell including the unit cell when the difference between the value of the performance parameter of any unit cell and the reference value of the performance parameter becomes larger than an initial difference;

when the difference between the value of the performance parameter of any single battery and the reference value of the performance parameter is smaller than the initial difference, the equalizing duty ratio of at least one single battery comprising the single battery is subjected to reduced adjustment.

19. The system of claim 17, wherein the control module is further configured to determine the single batteries in the battery pack that need to be balanced according to battery information of the single batteries; for the single batteries needing to be balanced, determining the balancing duty ratio of the single batteries needing to be balanced according to the battery information of each single battery; and setting the balance duty ratio of the single batteries which do not need to be balanced as a preset value.

20. The system according to claim 14, wherein the control module is connected with the acquisition module and the equalization module corresponding to the same battery cell through a channel, and the control module is configured to control the control module to be connected with the corresponding sampling module when it is determined that the battery cell connected with the control module does not need equalization; or,

21. The system of claim 20, wherein the control module comprises a control chip, and the control chip is connected with the acquisition module and the equalization module corresponding to the same cell through one pin and the one channel.

22. The system of claim 14, wherein the control module is connected to the collection module and the equalization module corresponding to the same cell through two channels.

23. The system according to claim 22, 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 battery cell through two pins, and the two pins are in one-to-one correspondence with the two channels.

24. A vehicle comprising a battery equalization system as claimed in any of claims 14-23.

25. 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 1-13.

26. An electronic device, comprising:

the computer-readable storage medium recited in claim 25; and