WO2019042357A1

WO2019042357A1 - Battery equalization method and system, vehicle, storage medium, and electronic device

Info

Publication number: WO2019042357A1
Application number: PCT/CN2018/103253
Authority: WO
Inventors: 罗红斌; 王超; 沈晓峰; 曾求勇; 刘苑红; 张祥
Original assignee: 比亚迪股份有限公司
Priority date: 2017-08-31
Filing date: 2018-08-30
Publication date: 2019-03-07
Also published as: CN110015178B; CN110015178A

Abstract

A battery equalization method, comprising: determining performance parameters of cells according to cell information of the cells of a battery pack within a sampling period of a unit cycle, the unit cycle comprising the sampling period and an equalization period; when the performance parameter of any of the cells in the battery pack satisfies an equalization duty cycle adjustment condition corresponding to the performance parameter, adjusting the equalization duty cycle of at least one of the cells comprising the cell in the battery pack, the equalization duty cycle being a ratio of the duration of the equalization period to the duration of the unit cycle, the performance parameter comprising at least one of the following parameters: voltage, SOC, internal resistance, self-charge rate, voltage change rate, power change rate, and time change rate. By means of the method, the duration of an acquisition period and the duration of the equalization period can be controlled, thereby improving equalization efficiency and reducing equalization costs. Also provided are a battery equalization system, a vehicle, a computer-readable storage medium, and an electronic device.

Description

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

Cross-reference to related applications

The present disclosure claims the priority of the Chinese Patent Application No. "201710776106.4" filed on August 31, 2017 by BYD Co., Ltd., entitled "Battery Equalization Method, System, Vehicle, Storage Medium, and Electronic Device."

Technical field

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

Background technique

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

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

At present, for the balanced management of the power battery pack, firstly, the single battery that needs to be equalized is determined from the power battery pack, so the battery information of each single battery in the power battery pack needs to be collected in real time, and then according to the battery information. To determine which cells need to be balanced, and then equalize the cells that need to be balanced. However, such a method may occur while collecting battery information, and also performing equalization, which may result in inaccurate battery information collected, resulting in poor balance.

Summary of the invention

It is an object of the present disclosure to provide a battery equalization method, system, vehicle, storage medium, and electronic device to improve the 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 unit battery according to battery information of each unit battery of the battery unit acquired during a sampling period of the unit period, where the unit period includes the sampling period and the equalization period;

An equalization duty ratio of at least one single cell including the single cell in the battery pack when a performance parameter of any one of the battery cells satisfies an equalization duty adjustment condition corresponding to the performance parameter Adjusting, the equalization duty ratio is a ratio of a duration of the equalization period to a duration of the unit period, and the performance parameter includes at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, Voltage change rate, power rate change rate, and time rate of change.

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

The collecting module is configured to collect battery information of each single battery of the battery pack during a sampling period of a unit period under the control of the control module;

The control module is configured to determine performance parameters of each single battery according to battery information of each single battery of the battery unit acquired during a sampling period of the unit period, where the unit period includes the sampling period and the equalization period; When the performance parameter of any single cell in the group satisfies the equalization duty adjustment condition corresponding to the performance parameter, the equalization duty ratio of at least one single cell including the single cell 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, and the performance parameter includes at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change Rate, rate of change in electricity, and rate of change in time;

The equalization module is configured to balance the cells that need to be equalized during the equalization 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 above second aspect.

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

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

a computer readable storage medium according to the fourth aspect;

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

Through the above technical solution, battery information collection and equalization and time sharing are performed to avoid battery information collection and equalization, so that the collected battery information is more accurate and the equalization effect is better; and in the process of charging or discharging the battery pack, The equalization duty cycle is adjusted to control the collection frequency of the battery information to ensure the safety of the battery pack. On the other hand, when the equalization duty ratio of the cell to be equalized is determined, according to the equalization duty ratio, in the case of setting the unit period, the duration of the acquisition period and the duration of the equalization period are controlled to achieve improvement. Balance efficiency and reduce equilibrium costs.

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

DRAWINGS

The drawings are intended to provide a further understanding of the disclosure, and are in the In the drawing:

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

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

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

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

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

6 is a schematic diagram of a voltage range for equalizing duty ratio adjustment according to an embodiment of the present disclosure;

7 is a schematic diagram of determining an equalization duty ratio of different single cells according to an embodiment of the present disclosure;

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

9 is a schematic flow chart of determining a balanced duty ratio of a single cell that needs to be equalized according to a voltage value and a reference voltage value of a single cell that are balanced according to an embodiment of the present disclosure;

10 is an open circuit voltage OCV-remaining power SOC curve of a single cell according to an embodiment of the present disclosure;

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

FIG. 12 is a schematic diagram of a determination process of a single cell requiring equalization according to an embodiment of the present disclosure; FIG.

FIG. 13 is a schematic flow chart of determining a cell that needs to be equalized according to a voltage according to an embodiment of the present disclosure; FIG.

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

15 is a schematic flow chart of an equalization process according to an embodiment of the present disclosure;

FIG. 16 is a schematic flowchart of an equalization duration acquisition according to an embodiment of the present disclosure.

Detailed ways

The specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are not to be construed

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

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

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

In this embodiment, the control module 101 controls the collection module 102 and the equalization module 103 to be turned on and off according to the unit period, respectively, and performs battery information collection and battery equalization processing, so that battery information collection and equalization processing are performed in a time-sharing manner. When the battery information collection and equalization processing are simultaneously performed, the influence of the equalization current on the accuracy of the battery information collection is affected.

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

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

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

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

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

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

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

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

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

Thus, by setting the switch between the control module and the acquisition module and the equalization module, the control module can achieve the function of acquisition and equalization by adjusting the state of the switch, and can achieve no sampling during equalization, and is unbalanced during sampling. The effect, so that the equalization current does not affect the battery voltage, thus improving the accuracy of the battery voltage sampling.

In one embodiment, as shown in FIG. 3, each of the cells in the battery is connected to an acquisition module 302 and an equalization module 303, respectively. If the battery pack includes N single cells, the number of the acquisition modules 302 is N, and the equalization module 303 is N. Thus, the control module 301 is connected to the acquisition module and the equalization module through N control channels.

In this embodiment of the present 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, thereby reducing the number of channels required for the control module chip.

For example, 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 cells correspond to 2N control channels. In the embodiment shown in FIG. 3, the acquisition module and the equalization module of the same single battery share a control channel and the control module is connected, and the N single cells correspond to N control channels, thereby reducing the number of control channels. Reduce the cost of the control module.

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 cells correspond to 2N control channels, and 2N control channels need to be controlled. In the embodiment shown in FIG. 3, the acquisition module and the equalization module of the same single battery share a control channel of the control module, so that the N single cells correspond to the N control channels, and only the N control channels need to be controlled. It can simplify the control process and reduce the misoperation rate of the control module.

In the embodiment shown in FIG. 1 , when the acquisition module and the equalization module are respectively connected to the control module through a control channel, the N single cells correspond to 2N control channels, and the pass rate of the control module is controlled by the control channel. The pass rate of 2N control channels is determined. In the embodiment shown in FIG. 3, the acquisition module and the equalization module of the same single battery share one control channel of the control module, and the N single cells correspond to N control channels, and the pass rate of the control module is controlled by the control channel. It is determined by the pass rate of the N control channels, which can improve the total pass rate of the plurality of single cells in the whole system through the control channel to the control module, thereby improving the pass rate of the battery equalization system.

In an embodiment of the present disclosure, the battery equalization system includes: a battery management controller (BMC) and a plurality of battery information collectors (BICs). In one embodiment, the control module described above 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 collecting module sends the parameter information of the single battery in the collected battery pack to the second control unit through the first control unit; wherein the collecting module and the equalizing module of the same single battery correspond to one control channel of the first control unit.

The first control unit may be connected to the collection module by controlling the connection channel, thereby controlling the collection module to collect parameter information of the single battery in the battery group. The second control unit may also send an acquisition instruction to the first control unit through the communication unit, so that the connection channel is connected to the collection module by the first control unit.

The first control unit may be connected to the equalization module by controlling the control channel, thereby controlling the equalization module to perform equalization processing on the single battery that needs to be turned on and equalized. The first control unit may send parameter information of the battery pack collected by the acquisition circuit to the second control unit, and the second control unit determines, according to parameter information of the battery pack, a single battery that needs to be turned on, and And transmitting, by the communication unit, an equalization instruction to the first control unit, to control, by the first control unit, that the control channel is connected to the equalization module.

When the acquisition module in the battery equalization system sends the parameter information of the single battery in the collected 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 the first control unit. A connection channel reduces the number of channels required by the first control unit.

According to an embodiment of the present disclosure, the first control unit of the battery information collector and the second control unit of the battery management controller can selectively perform equalization control on the unit cells that need to be equalized. That is, the first control unit may control the equalization module to perform equalization processing on the unit cells that need to be equalized, and the second control unit may also control the equalization module to perform equalization processing on the unit cells that need to be equalized. The first control unit or the second control unit determines the unit cells that need to be equalized according to the parameter information of the battery pack collected by the collection module.

When the battery information collector does not receive the equalization command sent by the battery management controller, the first control unit receives the parameter information of the battery pack, and determines according to the parameter information of the battery group. When a single battery in the battery pack needs to be turned on, the control equalization module performs equalization processing on the single battery that needs to be turned on.

When the battery information collector receives an instruction for instructing the battery information collector to perform equalization processing, the first control unit receives parameter information of the battery pack, and determines, according to parameter information of the battery pack, When a single battery in the battery pack needs to be turned on, the control equalization module performs equalization processing on the single battery that needs to be turned on.

When the battery information collector receives the battery management controller failure message, the first control unit receives the parameter information of the battery group, and determines, according to the parameter information of the battery group, that the battery group has a single When the battery needs to be turned on, the control equalization module performs equalization processing on the single cells that need to be turned on.

The battery information collector and the battery management controller can selectively control the equalization system through the first control unit and the second control unit, so that one of the battery information collector and the battery management controller can be disabled or malfunctioned. Underneath, the battery balancing system is still guaranteed to operate normally.

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

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

In an embodiment of the present disclosure, the unit period is divided into an acquisition period and an equalization period, and the ratio of the duration of the equalization period to the duration of the unit period is the equalization duty. The battery equalization method of the embodiment of the present disclosure determines the equalization duty ratio of the unit cells to be equalized that need to be equalized, and then controls the equalization of the cells to be equalized according to the determined equalization duty ratio to improve the equalization efficiency. Save on balancing costs.

As an embodiment of the present disclosure, the specific method of the equalization module and the equalization process is as follows:

Method 1: Passive equilibrium.

If the minimum value of the target parameter of each unit cell is used as the reference value of the target parameter, the equalization battery may be equalized by passive equalization, that is, the cell to be equalized is discharged, for example, set and balanced in the equalization module. The parallel resistance of the single cells reduces the difference between the target parameters of the cells to be equalized and the reference value to a preset range, and achieves the effect of equalizing the individual cells in the battery pack.

Method 2: Active balancing.

If the maximum value of the target parameter of each single cell is used as the reference value of the target parameter, the equalization process of the equalized cell may be performed by an active equalization method, that is, the battery to be equalized is charged, for example, a power supply component is set in the equalization module. (such as a generator or a battery), the difference between the target parameter of the unit cell to be equalized and the reference value is reduced to a preset range, and the effect of equalizing each unit cell in the battery pack is achieved.

Method 3: The combination of active and passive equalization.

If the average value or the median of the target parameters of each unit cell is used as the reference value of the target parameter, the unit cell whose target parameter is smaller than the reference value may be subjected to equalization processing in an active equalization manner, and the target parameter is greater than the reference value. The single cell is balanced by a passive equalization method, so that the difference between the target parameter and the reference value of the cell to be balanced is reduced to a preset range, and the effect of equalizing each cell in the battery pack is achieved.

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

In step S51, the performance parameters of each of the single cells are determined according to the battery information of each of the battery cells of the battery unit acquired during the sampling period of the unit cycle. The unit period includes the sampling period and the equalization period.

In step S52, when the performance parameter of any of the battery cells in the battery pack satisfies the equalization duty ratio adjustment condition corresponding to the performance parameter, balancing the at least one single cell including the single cell in the battery pack The duty cycle 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 parameter includes at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, power change rate, and time change rate.

In the embodiment of the present disclosure, as described above, the acquisition module and the equalization module are time-divisionally turned on according to the unit period, and the battery information is collected only during the sampling period. The duration of the sampling period per unit period and the duration of the equalization period can be determined according to the equalization duty ratio of each unit cell. The equalization duty ratio of each of the single cells in the battery pack may be the same or different. The equalization duty ratio of each unit cell can be a preset value or calculated based on battery information. Calculating the equalization duty ratio based on the battery information will be described in the subsequent embodiments.

When the battery pack is in the process of charging or discharging, it is necessary to ensure safety. Therefore, the embodiment of the present disclosure realizes the control of the frequency of battery information collection by adjusting the equalization duty ratio.

In an embodiment of the present disclosure, when 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 when the battery pack is in a charging state, the battery is The adjustment of the equalization duty ratio of at least one of the cells including the single cell in the group is reduced; or

When the battery pack is in a discharged state, when the value of the performance parameter of any of the single cells is less than a second predetermined threshold corresponding to the performance parameter, at least one single cell including the single cell in the battery pack is included The equalization duty ratio of the body battery is adjusted to be reduced.

In the embodiment of the present disclosure, the equalization duty ratio is adjusted, and the equalization duty ratio of the single battery whose performance parameter reaches the adjustment threshold can be adjusted, and the equalization duty ratio of all the single cells can also be adjusted.

The performance parameter can be voltage. If the voltage of any single cell reaches the high voltage alarm during the charging process of the single battery, in order to ensure the safety of the single battery and prevent overcharging of the single battery, it is necessary to strengthen the single battery. Real-time monitoring reduces the equilibrium duty cycle of the system and increases the battery information collection frequency of the single battery to monitor the state of the single battery in real time. In the discharge process of the single battery, when any single battery voltage reaches the low voltage alarm, in order to ensure the safety of the single battery and prevent the over discharge of the single battery, it is necessary to strengthen the real-time monitoring of the single battery, then reduce The balanced duty cycle of the system increases the battery information collection frequency of the single battery to monitor the battery status in real time.

During the charging of the battery pack, the first preset threshold is a first preset high threshold or a second preset high threshold, and the second preset high threshold is greater than the first preset high threshold. Then the above step S52 includes:

When the battery pack is in a charging state, the voltage value of any of the single cells is higher than the first preset high voltage threshold, and the equalization duty ratio of at least one of the single cells including the single battery is decreased. Adjustment;

When the battery pack is in a charging state, the voltage value of any of the single cells is higher than the second predetermined high voltage threshold, and the equalization duty ratio of at least one of the single cells including the single cells is adjusted to zero.

During the discharge of the battery pack, the second preset threshold is a first preset low threshold or a second preset low threshold, and the second preset low threshold is smaller than the first preset low threshold. Then the above step S52 includes:

When the battery pack is in a discharged state, when the voltage value of any of the single cells is lower than the first predetermined low voltage threshold, the equalization duty ratio of at least one of the single cells including the single cell is decreased. Adjustment

When the battery pack is in a discharged state, when the voltage value of any of the single cells is lower than the second predetermined low-voltage threshold, the equalization duty ratio of at least one of the single cells including the single battery is adjusted to 0. .

Referring to Figure 6, the adjustment of the battery equalization duty cycle is divided into different levels depending on the degree of danger of the battery voltage. Vh1 is the first preset high-voltage threshold (general high-voltage alarm value), Vh2 is the second preset high-voltage threshold (serious high-voltage alarm value), Vl1 is the first preset low-voltage threshold (general low-voltage alarm value), and Vl2 is the second pre- Set the low pressure threshold (serious low voltage alarm value), then:

(1) when the voltage V ∈ (Vl1, Vh1) of any single cell, the equilibrium duty of the cell is τ1;

(2) when any cell voltage V ∈ (Vl2, Vl1) or V ∈ [Vh1, Vh2), the equilibrium duty cycle of the cell is adjusted to τ2;

(3) When any cell voltage V ≤ Vl2 or V ≥ Vh2, the equalization duty ratio of the unit cell is adjusted to τ3. Where 0 ≤ τ3 < τ2 < τ1 < 1.

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

When the initial difference is larger than the difference between the value of the performance parameter of any of the single cells and the reference value of the performance parameter, the equalization duty ratio of at least one of the single cells including the single cell is performed Increased adjustment;

When the difference between the value of the performance parameter of any of the single cells and the reference value of the performance parameter is smaller than the initial difference, the equalization duty ratio of at least one of the single cells including the single cell is subtracted Small adjustments.

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

(1) When the voltage difference ΔV between the voltage of any single cell and the voltage reference value is constant, the equilibrium duty ratio of each cell is kept unchanged;

(2) When the voltage difference ΔV becomes larger, to ensure that the equalization task is completed within the total time required by the system, increase the equalization duty ratio to k1 times the original equalization duty ratio (k1>1) to speed up Equilibrium speed. The increased equalization duty cycle here can be to increase the equalization duty ratio of all the single cells.

(3) When the voltage difference ΔV becomes small, the equilibrium duty ratio of the system can be reduced to k2 times the original duty ratio (0<k2<1), and the frequency of battery information collection is increased to increase battery information. Acquisition frequency. The reduced equalization duty cycle here can be to reduce the equalization duty cycle of all single cells.

Thereby, the adjustment of the equalization duty ratio can be realized according to the change of the performance parameter of the single battery, the frequency of collecting the 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 battery cells in the battery pack that need to be equalized are determined according to the battery information of each unit battery.

In step S72, for the unit cells that need to be equalized, the equalization duty ratio of the unit cells that need to be equalized is determined according to the battery information of each unit battery.

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

In the embodiment of the present disclosure, initially, for example, when the battery pack is initially charged or discharged, when the first acquisition is performed, the duration of the acquisition period of the unit period and the duration of the equalization period may be determined according to the preset value of the equalization duty ratio. The preset value can be the initial equalization duty cycle or the equalization duty ratio of each single cell when the last battery pack is stopped. In one embodiment, the initial equalization duty cycle can be set to zero, ie, only acquisition is performed.

After determining the equalization duty ratio of the unit cells requiring equalization, the duration of the acquisition period of the unit period of the unit cells requiring equalization and the duration of the equalization period are determined according to the newly determined equalization duty ratio. For a single cell that does not need to be equalized, the duration of the acquisition period of the unit period and the duration of the equalization period may be determined according to the preset value of the equalization duty ratio, and the battery information is collected during the collection period, but the equalization is not performed during the equalization period. For a single cell that needs to be equalized, the equalization duty ratio can be determined according to the method shown in FIG. 8:

In step S81, based on the battery information of each unit battery, the value of any one of the following performance parameters of each unit cell is obtained: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, power rate change rate, and Time rate of change.

In step S82, a reference value of the target performance parameter is determined according to a value of a target performance parameter of each unit battery, and the target performance parameter is any one of the following performance parameters: voltage, SOC, internal resistance, and self Discharge rate, voltage change rate, power change rate, and time change rate.

In step S83, the equalization duty ratio of the unit cells that need to be equalized is determined according to the reference value of the target performance parameter and the value of the target performance parameter of the unit cell that needs to be equalized.

In an embodiment of the present disclosure, the difference between the value of the target performance parameter of the unit cell that needs to be equalized and the reference value of the target performance parameter, and the difference between the target performance parameter and the reference value of the target performance parameter and the balance account. The preset correspondence of the ratios determines the equalization duty of the cells that need to be equalized. For example, when the target performance parameter is voltage, different voltage differences have a corresponding relationship with the equalization duty ratio. According to the corresponding relationship, the equalization of the cells that need to be balanced can be obtained according to the voltage of the single cell that needs to be balanced. Empty ratio. The reference value of the target performance parameter may be the maximum value, the minimum value or the average value of the target performance parameters of each unit cell.

In the following embodiments, the target performance parameters are respectively voltage, SOC, internal resistance, self-discharge rate, voltage change rate, power change rate, and time change rate, and another acquisition mode of the equalization duty ratio will be described.

When the target performance parameter is voltage, referring to FIG. 9, the steps of determining the equalization duty ratio of the unit cells that need to be equalized according to the voltage value and the reference voltage value of the unit cells that need to be equalized include:

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

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 power SOC curve of the reference battery.

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

In step S94, the equalization duty ratio of the unit cells that need to be equalized is determined based on the first SOC value and the second SOC value.

Referring to FIG. 10, an open circuit voltage OCV-remaining power SOC curve of a single cell according to an embodiment of the present disclosure is shown.

The above step S92 includes:

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

The above step S93 includes:

Determine the OCV value of the cell to be balanced according to the voltage value of the cell to be balanced and the internal resistance of the cell to be balanced; and then determine the need according to the OCV-SOC curve of the cell to be balanced. The SOC value corresponding to the OCV value of the balanced unit cell is the second SOC value.

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

Referring to FIG. 11 and formula (1), when the battery pack is in a discharged state or a charged state, the battery internal resistance model is used, and the single battery is equivalent to an ideal voltage source in series with the resistor R. Then, for a single cell, the sampled voltage value V _L (ie, the load voltage value) of the single cell can be converted into an open circuit voltage value according to formula (1):

OCV=V _L +I×R (1)

Wherein, V _L is a load voltage value collected by the acquisition module during the acquisition period; I is a discharge current or a charging current collected by the acquisition module during the acquisition period; and R is an internal resistance value of the single battery.

The internal resistance of the single cell can be preset. Alternatively, the internal resistance of the unit cell may be determined based on the voltage and capacity of the unit cell. For example, the internal resistance value of the unit cell is determined according to the correspondence relationship between the voltage, the capacity, and the internal resistance value of the unit cell. It should be understood that other battery models, such as Thevenin model, PNGV (partnership for a new generation of vehicles) model, etc., can be used to convert the load voltage of the collected single cells. Is the open circuit voltage.

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

It should be understood that the OCV-SOC curve shown in FIG. 10 can 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 is obtained by measurement. For example, for a single cell, in the process of changing its SOC value from 0 to 100%, every time a certain SOC value is separated, the open circuit voltage OCV of the battery is measured once, and then the OCV of each point is corresponding. The SOCs correspond one-to-one to form a SOC-OCV curve or an OCV-SOC correspondence table of the unit cells.

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

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

Next, determine the difference in charge according to equation (2):

ΔQ=ΔSOC×C _n (2)

Where ΔQ is the difference in electric quantity, ΔSOC is the SOC difference between the first SOC value and the second SOC value, and C _n is the usable capacity of the unit cell to be equalized.

According to formula (3), determine the equilibrium duty ratio of the cells that need to be balanced:

τ=(ΔQ/I)/t (3)

Where t is the preset equalization period of the cell to be balanced, I is the preset equalization current of the cell to be equalized, and τ is the equalization duty. The preset equalization current can be determined according to the resistance of the equalization module, the current that the generator can provide, or the actual equalization requirement.

In an embodiment, when the target performance parameter is: the SOC value, 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 unit cell that needs to be equalized, including:

The electric quantity difference is determined according to ΔQ=ΔSOC×C _n , where ΔQ is the electric quantity difference, ΔSOC is the SOC difference between the SOC value of the unit cell requiring equalization and the reference value of the SOC, and C _n is a single cell requiring equalization Available capacity;

According to τ=(ΔQ/I)/t, the equalization duty ratio of the cell to be equalized is determined, where t is the preset equalization time of the cell to be balanced, and I is the preset of the cell requiring equalization. Equalize the current, τ is the equalization duty cycle.

It should be understood that when the battery information of the single cells is collected, the SOC value of each single cell can be obtained according to the ampere integration method or the open circuit voltage method. In one embodiment, the equalization duty ratio may be determined by combining the voltage and the SOC. When the SOC value of each single battery in the battery pack, the number of SOC values belonging to the first preset interval is greater than or equal to the first When the number of SOC values of the preset interval is determined, the equalization duty ratio of the unit cells that need to be equalized is determined according to the manner that the target performance parameter is SOC;

When the SOC value of each single battery in the battery pack is less than the number of SOC values that are not in the first preset interval, the target performance parameter is a voltage mode. Determine the equilibrium duty cycle of the cells that need to be balanced.

Or determining a reference SOC value according to the SOC value of each single battery in the battery pack; when the reference SOC value belongs to the second preset interval, determining the equalization of the single battery to be equalized according to the target performance parameter being the SOC Duty cycle; when the reference SOC value does not belong to the second preset interval, the equalization duty ratio of the unit cells that need to be equalized is determined according to the manner that the target performance parameter is voltage.

In one embodiment, when the target performance parameter is an internal resistance, the equalization duty ratio is determined according to the reference value of the target performance parameter and the value of the target performance parameter of the unit cell to be equalized, including:

The single battery that minimizes the difference between the internal resistance value of the battery pack and the reference value of the internal resistance value is determined 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 the open circuit voltage OCV-remaining power SOC curve corresponding to the reference battery;

According to the internal resistance value of the cell that needs to be balanced, the voltage value of the cell that needs to be balanced, the current value of the cell that needs to be balanced, and the OCV-SOC curve corresponding to the cell that needs to be balanced, it is determined and balanced. a second SOC value corresponding to an internal resistance value of the single cell;

Based on the first SOC value and the second SOC value, an equalization duty ratio of the unit cells that need to be equalized is determined.

It should be understood that determining the first SOC value, determining the second SOC value, and determining the equalization duty ratio according to the first SOC value and the second SOC value may participate in the embodiment in which the target performance parameter is a voltage, and no longer Narration.

In one embodiment, when the target performance parameter is the self-discharge rate, the equalization duty ratio is determined according to the reference value of the target performance parameter and the value of the target performance parameter of the unit cell to be equalized, including:

The single cell that minimizes the difference between the self-discharge rate value and the self-discharge rate value in the battery pack is determined as a reference battery;

According to the self-discharge rate value of the single cell that needs to be balanced and the reference self-discharge rate value, the power difference between the single cell and the reference battery that need to be balanced is obtained;

The equalization duty ratio is determined according to the preset equalization current, the preset equalization duration, and the electric quantity difference.

In one embodiment, the power difference is: ΔQ=Δη×t, where Δη is the difference between the self-discharge rate value of the cell that needs to be equalized and the self-discharge rate value of the reference battery, and t is the monomer that needs to be balanced. The interval between the battery and the end of the previous equalization.

The method for determining the equalization duty ratio according to the preset equalization current, the preset equalization duration, and the electric quantity difference is shown in the above formula (3).

In one embodiment, the self-discharge rate values of the individual cells in the battery pack can be obtained according to the following method:

After the battery pack is powered off, determining, for each of the single cells in the battery pack, a first time when the single battery reaches a steady state and a first open circuit voltage value corresponding to the single battery at the first time;

When the battery pack is powered on again, determining, for each of the single cells in the battery pack, a second time when the single battery is powered on and a second open circuit voltage value of the single battery at the second time;

And the voltage difference according to a voltage difference between the first open circuit voltage value and the second open circuit voltage value corresponding to the single battery, and a time length between the first time and the second time corresponding to the single battery The ratio to the duration is determined as the self-discharge rate value of the unit cell.

In one embodiment, when the target performance parameter is a voltage change rate, the equalization duty ratio is determined according to the reference value of the target performance parameter and the value of the target performance parameter of the unit cell to be equalized, including:

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

When the initial terminal voltage of the cell to be balanced is different from the initial voltage of the reference cell, the equalization of the cell to be balanced is determined according to the initial terminal voltage of the cell to be balanced and the initial terminal voltage of the reference cell. Duty cycle

When the initial terminal voltage of the cell to be equalized is the same as the initial terminal voltage of the reference battery, the balance of the cell to be balanced is determined according to the terminal voltage of the cell to be balanced and the terminal voltage of the reference cell. Empty ratio.

In one embodiment, the voltage change rate values of the individual cells can be obtained as follows:

During the charging or discharging process of the battery pack, it is determined that the predetermined amount of power is charged or discharged to each of the single cells, and the amount of voltage change of each of the single cells is charged or discharged to the single battery. The difference between the front initial terminal voltage and the terminal voltage after charging or discharging the preset battery power;

For each of the single cells in the battery pack, determining a voltage change rate of the single cell is a ratio of a voltage change amount of the single cell to the preset amount of electricity.

In another embodiment, the voltage change rate values of the individual cells can be obtained as follows:

During the charging or discharging process of the battery pack, determining a preset duration for charging or discharging each of the single cells, and a voltage variation amount of each of the single cells, the voltage change amount is a preset time for charging the single battery or a discharge preset The difference between the initial terminal voltage before the duration and the preset terminal length for charging the single battery or the terminal voltage after the preset duration of the discharge;

For each of the single cells in the battery pack, determining a voltage change rate of the single cell is a ratio of a voltage change amount of the single cell to the preset duration.

It should be understood that, according to the initial terminal voltage of the unit cell that needs to be equalized and the initial terminal voltage of the reference battery, the equalization duty ratio of the unit cells that need to be equalized, or the terminal voltage of the unit cell and the reference battery that are equalized according to the need are determined. The most terminal voltage, the method of determining the equalized duty ratio of the cell to be balanced, and the embodiment in which the target performance parameter is voltage, determining the equalization duty ratio according to the voltage and reference voltage of the cell to be equalized The method is the same and will not be described here.

In one embodiment, when the target performance parameter is the power 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 unit cell that needs to be balanced, including:

The single battery that minimizes the difference between the power change rate value in the battery pack and the reference power change rate value is determined as a reference battery;

When the initial terminal voltage of the cell to be balanced is the same as the initial terminal voltage of the reference battery, the voltage of the cell balanced according to the need to rise from the initial terminal voltage by one unit voltage and the voltage of the reference battery are The amount of charge required to increase the initial terminal voltage by one unit voltage, determine the equalization duty ratio of the unit cells that need to be equalized, or the amount of power that is reduced by one unit voltage from the initial terminal voltage according to the voltage of the unit cell that needs to be equalized And the voltage of the reference battery is reduced by one unit voltage from the initial terminal voltage, and the equalization duty ratio of the cell to be balanced is determined.

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

During the charging process of the battery pack, the amount of charge required to increase the voltage of each single cell from the initial terminal voltage by one unit voltage is obtained;

For each of the single cells in the battery pack, determining a change rate of the amount of charge of the single cell is a ratio of a value of the amount of charge required to be charged to the cell to a value of the unit voltage; or

During the discharge process of the battery pack, the amount of power reduced by one unit voltage from the initial terminal voltage is obtained;

For each of the battery cells in the battery pack, determining a power change rate value of the single battery battery is a ratio of a value of the reduced power amount of the single battery to a value of the unit voltage.

In one embodiment, a method of determining an equalization duty ratio of a cell requiring equalization according to an initial terminal voltage of a cell to be balanced and an initial terminal voltage of a reference cell, and an embodiment in which the target performance parameter is a voltage The method for determining the equalization duty ratio according to the voltage of the cell to be balanced and the reference voltage value is the same, and will not be described herein.

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

The amount of charge required to increase the voltage of the unit cell from the initial terminal voltage by one unit voltage and the voltage of the reference battery from the initial terminal voltage by one unit voltage or the unit cell to be equalized according to needs The amount of voltage reduced from the initial terminal voltage by one unit voltage and the reference battery voltage decreased by one unit voltage from the initial terminal voltage, determining the difference between the battery cells requiring the equalization and the reference battery;

According to the power difference, the preset equalization duration, and the preset equalization current, the equalization duty ratio of the single cell to be equalized is determined. In one embodiment, referring to equation (3) above, the equalization duty cycle can be determined.

In one embodiment, when the target performance parameter is a time change rate, the equalization duty ratio is determined according to the reference value of the target performance parameter and the value of the target performance parameter of the unit cell to be equalized, including:

The single battery that minimizes the difference between the time change rate value and the reference time change rate value in the battery pack is determined as a reference battery;

When the initial terminal voltage of the cell to be equalized is the same as the initial terminal voltage of the reference battery, the charging time of the single cell and the charging time of the reference battery according to the need, or the discharge time of the cell balanced according to the need and Refer to the discharge time of the battery to determine the equilibrium duty cycle of the cells that need to be balanced.

In one embodiment, obtaining time rate of change values for each of the cells includes:

During the charging process of the battery pack, the charging time required for the voltage of each single cell to rise by one unit voltage from the initial terminal voltage is obtained;

For each single cell in the battery pack, determining a time change rate value of the single cell is a ratio of a required charging time of the single cell to a value of the unit voltage; or

During the discharge process of the battery pack, the discharge time required for the voltage of each unit cell to decrease by one unit voltage from the initial terminal voltage is obtained;

For each of the unit cells in the battery pack, determining the time rate of change of the unit cell is a ratio of a desired discharge time of the unit cell to a value of the unit voltage.

In one embodiment, when the initial terminal voltage of the unit cell that needs to be equalized is the same as the initial terminal voltage of the reference battery, determining an equalization duty ratio of the unit cells that need to be equalized includes:

According to the charging time required for the voltage of the cell to be equalized to rise by one unit voltage from the initial terminal voltage, the charging time required for the voltage of the reference battery to rise by one unit voltage from the initial terminal voltage, and the current integral value, determine the need for equalization The power of the body battery and the reference battery is poor, or the discharge time required for the voltage of the single cell to be equalized by one unit voltage from the initial terminal voltage, and the voltage of the reference battery is decreased by one unit voltage from the initial terminal voltage. Determining the required discharge time and the current integrated value to determine the difference in the amount of electricity between the single cell and the reference battery that need to be equalized;

And determining, according to the power difference, the preset equalization duration, and the preset equalization current, an equalization duty ratio of the single cell that needs to be equalized. In one embodiment, referring to equation (3) above, the equalization duty cycle can be determined.

In an embodiment of the present disclosure, in addition to adjusting the equalization duty ratio of the single cell that needs to be equalized, the adjustment of the equalization duty ratio includes:

In the equalization process of the unit cells requiring equalization, when the difference between the value of the target performance parameter of the unit cell requiring equalization and the reference value of the target performance parameter becomes larger than the difference at the start of the equalization, The equilibrium duty ratio of the balanced single cells is increased and adjusted;

In the equalization process of the unit cells requiring equalization, when the difference between the value of the target performance parameter of the unit cell requiring equalization and the reference value of the target performance parameter becomes smaller than the difference at the start of the equalization, the balance needs to be equalized. The equalization duty ratio of the single cells is adjusted to be reduced.

Therefore, for the single cell that needs to be balanced, in addition to the above-described equalization duty adjustment mode, the equalization duty ratio can be adjusted according to the value of the target performance parameter during the equalization process to ensure balanced safety. And efficiency.

After adjusting the equalization duty ratio of the single battery, according to the adjusted equalization duty ratio, the duration of the acquisition period and the duration of the equalization period are controlled in the case of setting the unit period to improve the equalization efficiency and reduce the equalization. cost.

Referring to FIG. 12, in an embodiment of the present disclosure, in the foregoing step S71, the single cell that needs to be equalized can be determined by:

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

In step S122, in the at least one unit cell, the difference between the performance parameter and the reference value of the performance parameter is greater than or equal to the unit cell with the equalization on threshold as the unit cell that needs to be equalized and needs to be equalized.

It should be understood that the equalization on threshold corresponds to the performance parameter.

As described above, when the performance parameter is voltage, the above steps of determining a unit cell requiring equalization are shown in FIG. 13:

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

In an embodiment of the present disclosure, a minimum voltage value among voltage values of each of the battery cells in the battery pack may be determined as a reference voltage value; or, a maximum voltage value among voltage values of each single battery in the battery pack Determined as a reference voltage value; or, the average value of the voltage values of the individual cells in the battery pack is determined as a reference voltage value.

In step S132, the single cell in which the voltage difference between the voltage value and the reference voltage value is greater than or equal to the equalization turn-on threshold in at least one of the cells is determined as a cell that needs to be equalized and needs to be equalized.

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

Comparing the voltage value of the single cell having the largest voltage value in the battery pack with the reference voltage value; or the voltage value and the reference voltage value of the single cell other than the single cell except the voltage value in the battery pack Compare.

When the reference voltage value is the minimum value of the voltage values of the individual cells, the subsequent equalization process for the determined cell that needs to be equalized is: controlling the cell discharge requiring equalization to perform passive equalization.

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

Comparing the voltage value of the single cell with the lowest voltage value in the battery pack with the reference voltage value; or the voltage value and the reference voltage value of the single cell other than the single cell in the battery pack except the voltage value being the maximum value Compare.

When the reference voltage value is the maximum value of the voltage values of the individual cells, the subsequent equalization process for the determined cell that needs to be equalized is: controlling the cell charging that needs to be balanced, and performing active equalization.

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

The voltage values of the individual cells in the battery pack are compared with the reference voltage values, respectively.

When the reference voltage value is an average value of the voltage values of the individual cells, the subsequent equalization process for the determined cell that needs to be equalized is: charging the cell with the control voltage value smaller than the reference voltage value, performing active equalization; The single cell with a voltage value greater than the reference voltage value is discharged, and passive equalization is performed.

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

Table 1

Therefore, when the equalization judgment is made using the performance parameters of different batteries, the judgment is made according to the corresponding manner in Table 1, and the unit cell in the battery pack that needs to be equalized is determined in combination with the judgment flow in which the performance parameter is the voltage.

It should be understood that if there is no single cell that needs to be equalized, the equalization judgment is continued according to the information collected in the next acquisition period. When it is determined that there is no single cell that needs to be equalized according to the information collected during the collection period, during the equalization period, the control module may not operate, so that the equalization modules corresponding to any battery are not turned on.

Equilibrium process

Referring to FIG. 14 , it is a schematic diagram of an equalization module according to an embodiment of the present disclosure. The unit cells that need to be balanced are balanced in the equalization period of the unit period, and need to be combined with the above-mentioned equalization judgment. According to the step of equalization judgment (as described in steps S121 and S122 above), it is determined that the equalization mode of the unit cells that need to be equalized is passive equalization (that is, discharge of the single cells that need to be balanced), or active equalization (ie, for the need) The balanced single cell is charged) and the corresponding equalization module is turned on.

Referring to FIG. 14, for passive equalization, the equalization module includes: a resistor 811, each of which corresponds to an equalization module, that is, a resistor is connected in parallel with each end of each unit cell.

For a cell that needs to be balanced for passive equalization, the control module controls the parallel loop conduction between the cell that needs to be equalized and its corresponding resistor during the equalization period of the unit period to execute the cell. Passive equilibrium. Referring to FIG. 14, the control module is turned on by controlling the switch module 812 to realize conduction of a parallel circuit between the cell requiring equalization and its corresponding resistor.

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

Referring to FIG. 14, for active equalization, the equalization module includes a charging branch 94 connected in parallel with each of the unit cells 95 in the battery pack. The charging branch 94 is in one-to-one correspondence with the unit cells 95, and each charging branch 94 is provided. Both are coupled to a generator 92 that is mechanically coupled to the engine 91 via a gear.

For a single cell that needs to be actively equalized and needs to be balanced, the control module controls the charging branch 94 corresponding to the cell that needs to be balanced to be turned on. When the engine 91 rotates, the generator 92 is driven to generate electricity, so that the amount of power generated by the generator 92 is supplied to the unit cells that need to be balanced, so that the amount of the cells that need to be balanced is increased.

Referring to FIG. 14, when the generator 92 is an alternator, the equalization module further includes a rectifier 93 in series with the generator 92, each of the charging branches 130 being connected in series with the rectifier 132. After the alternating current generated by the generator 92 is converted to direct current by the rectifier 93, the generator 92 can be enabled to charge the unit cells that need to be equalized.

Referring to FIG. 14, the control module can be turned on by controlling the switch 96 corresponding to the unit cell that needs to be balanced, so that the charging branch corresponding to the unit cell that needs to be balanced is turned on, and the active equalization of the unit cells that need to be balanced is performed. .

In other embodiments, in addition to charging the unit cells with a generator as shown in FIG. 14, the unit cells that need to be balanced can be charged by the starting battery in the vehicle.

In another embodiment, in addition to the parallel resistors and the single cells that need to be balanced, as shown in FIG. 14, the cells that need to be balanced can be connected in parallel with the starting batteries of the vehicle, and the cells that need to be balanced are discharged. The power is charged into the starting battery to achieve equalization of the cells that need to be balanced while effectively avoiding waste of energy.

As described above, in the embodiment of the present disclosure, a plurality of single cells may share one equalization module, and when at least two of the multi-cell cells sharing one equalization module need to be equalized, in a unit period During the equalization period, the equalization module is alternately connected with each of the at least two single cells that need to be equalized, and is separately equalized.

In an embodiment of the present disclosure, when equalizing the cells that need to be equalized according to the equalization duty ratio, the cumulative equalization time of the cells that need to be equalized is reached to the preset equalization time. Since the duration of a single unit period is limited, the equalization of a unit cell requiring equalization may occur during an equalization period of one or more unit periods.

Referring to FIG. 15, in step S151, the control module controls a control channel of the unit cells that need to be equalized, which needs to be equalized, and equalizes the cells that need to be equalized during the equalization period.

In step S152, when the single equalization period ends, the control module determines whether the equalization of all the cells that need to be equalized is completed, that is, whether the cumulative equalization duration of all the cells that need to be equalized has reached the corresponding preset equalization duration. If the equalization duration of all the cells that need to be balanced has been met, step S154 is performed; if the equalization period of any of the cells requiring equalization does not meet the requirements, step S153 is performed.

When equalizing the cells that need to be equalized in the equalization period, when the cumulative equalization time of any cell that needs to be equalized reaches the corresponding preset equalization duration, the equalization of the cells that need to be balanced is controlled. stop.

In step S153, when the single unit period ends, if the cumulative equalization period of any unit cell that needs to be equalized does not reach its corresponding preset equalization period, after the sampling period of the next unit period ends, within the equalization period Continue to control the equalization of the cells that have not reached the equalization time, and step S152 is performed.

In step S154, a new round of equalization determination is started, and according to the battery information collected during the collection period, the unit cells that need to be equalized need to be equalized and the equalization duty ratio of each unit cell that needs to be balanced is determined.

It should be understood that in the new round of equalization determination, the determination of the unit cells requiring equalization and the determination of the equalization duty ratio of the unit cells requiring equalization may be performed in the foregoing manner.

For the preset equalization period of the single cell that needs to be equalized in the above embodiment, it may be preset to a fixed value according to the actual equalization requirement, for example, according to the extended variation of the cell difference with time, and the equalization function capability of the system. Request, etc., preset the equalization time to a fixed value. In addition, the preset equalization duration required for the current equalization may be determined according to the historical balance of the unit cells that need to be equalized in the following manner.

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

In step S162, the historical equalization duration and the historical parameter information of the unit cells that need to be equalized are acquired, and the historical parameter information is historical information of the target parameter information.

In step S163, based on the target parameter information, the historical equalization duration, and the historical parameter information, the equalization duration required for the current equalization of the cells to be equalized is determined. The equalization duration is used as the preset equalization duration.

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

Where t _k is the equalization duration; t _k-1 is the historical equalization duration of the previous equalization of the cell to be equalized; ΔS _k is the current time, and the target parameter of the cell to be balanced and the reference value of the target parameter are required The difference between ΔS _k-1 is the difference between the target parameter of the unit cell and the reference value of the target parameter that needs to be equalized at the last equilibrium time; C _k is the current time, and the cell of the equalization is required. Current available capacity; C _k-1 is the last available time, and the historical available capacity of the balanced single cell is required.

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

In one embodiment, the control module is configured to: when the battery pack is in a charging state, when 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, Adjusting the equalization duty ratio of at least one of the single cells including the single cell in the battery pack; or

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

The control module is configured to: when the battery pack is in a charging state, a voltage value of any single battery is higher than the first preset high voltage threshold, and balance the at least one single battery including the single battery The adjustment of the duty cycle is reduced;

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

The control module is configured to: when the battery pack is in a discharging state, when the voltage value of any single battery is lower than the first preset low voltage threshold, to at least one single battery including the single battery The equalization duty ratio is adjusted to be reduced; when the battery pack is in a discharged state, when the voltage value of any of the single cells is lower than the second predetermined low voltage threshold, at least one single cell of the single battery is included The equalization duty cycle of the body battery is adjusted to zero.

In one embodiment, the control module is configured to include the single cell when the value of the performance parameter of any of the single cells is greater than the difference between the reference values of the performance parameters. The adjustment of the equalization duty ratio of at least one of the cells of the battery is increased;

In one embodiment, the control module is further configured to determine, according to battery information of each unit battery, a single unit in the battery pack that needs to be balanced; and for the unit battery that needs to be balanced, according to each unit The battery information of the battery determines the equalization duty ratio of the single battery that needs to be equalized; for the single battery that does not need to be balanced, the equalization duty ratio is set to a preset value.

In one embodiment, the control module is connected to an acquisition module and an equalization module corresponding to the same single cell through a channel, and the control module is configured to determine that the single battery connected to the control module does not need to be equalized. Controlling the control module to connect with a corresponding sampling module; or

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

In one embodiment, the control module includes a control chip that is coupled to the acquisition module and the equalization module corresponding to the same single cell through a pin and the one channel.

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

In one embodiment, the control module includes a control chip, and the control chip is respectively connected to an acquisition module and an equalization module corresponding to the same single cell through two pins, the two pins and the two The channels correspond one by one.

With regard to the system in the above embodiment, the specific manner in which the respective modules perform the operations has been described in detail in the embodiment relating to the method, and will not be explained in detail herein.

Accordingly, embodiments of the present disclosure also provide a vehicle including the battery equalization system described above.

Correspondingly, an embodiment of the present disclosure further provides a computer readable storage medium having stored thereon computer program instructions, which are implemented by a processor to implement the battery equalization method described above.

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

The preferred embodiments of the present disclosure have been described in detail above 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 can be made to the technical solutions of the present disclosure within the scope of the technical idea of the present disclosure. These simple variations are all within the scope of the disclosure.

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

In addition, any combination of various embodiments of the present disclosure may be made as long as it does not deviate from the idea of the present disclosure, and should also be regarded as the disclosure of the present disclosure.

Claims

A battery equalization method, comprising:

Determining performance parameters of each unit battery according to battery information of each unit battery of the battery unit acquired during a sampling period of the unit period, where the unit period includes the sampling period and the equalization period;

An equalization duty ratio of at least one single cell including the single cell in the battery pack when a performance parameter of any one of the battery cells satisfies an equalization duty adjustment condition corresponding to the performance parameter Adjusting, the equalization duty ratio is a ratio of a duration of the equalization period to a duration of the unit period, and the performance parameter includes at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, Voltage change rate, power rate change rate, and time rate of change.
The method according to claim 1, wherein when the performance parameter of any one of the battery cells satisfies an equalization duty adjustment condition corresponding to the performance parameter, the battery pack is included The equalization duty ratio of at least one of the single cells of the single cell is adjusted, including:

When the battery pack is in a charging state, when the value of the performance parameter of any of the single cells is greater than or equal to a first predetermined threshold corresponding to the performance parameter, at least the single battery of the battery pack is included The adjustment of the equalization duty ratio of a single cell is performed; or

When the battery pack is in a discharged state, when the value of the performance parameter of any of the single cells is less than a second predetermined threshold corresponding to the performance parameter, at least one single cell including the single cell in the battery pack is included The equalization duty ratio of the body battery is adjusted to be reduced.
The method according to claim 2, wherein the performance parameter is a voltage, the first preset threshold is a first preset high threshold or a second preset high threshold, and the second preset high threshold Greater than the first preset high voltage threshold;

Adjusting the equalization duty ratio of the at least one single cell including the single battery in the battery pack, including:

When the battery pack is in a charging state, the voltage value of any of the single cells is higher than the first preset high voltage threshold, and the equalization duty ratio of at least one of the single cells including the single battery is decreased. Adjustment;

When the battery pack is in a charging state, the voltage value of any of the single cells is higher than the second predetermined high voltage threshold, and the equalization duty ratio of at least one of the single cells including the single cells is adjusted to zero.
The method according to claim 2, wherein the performance parameter is a voltage, the second preset threshold is a first preset low threshold or a second preset low threshold, and the second preset low threshold is Less than the first preset low pressure threshold;

Adjusting the equalization duty ratio of each single battery in the battery pack, including:

When the battery pack is in a discharged state, when the voltage value of any of the single cells is lower than the first predetermined low voltage threshold, the equalization duty ratio of at least one of the single cells including the single cell is decreased. Adjustment

When the battery pack is in a discharged state, when the voltage value of any of the single cells is lower than the second predetermined low-voltage threshold, the equalization duty ratio of at least one of the single cells including the single battery is adjusted to 0. .
The method according to any one of claims 1 to 4, wherein when the performance parameter of any one of the battery cells satisfies an equalization duty adjustment condition corresponding to the performance parameter, The equalization duty ratio of each single cell in the battery pack is adjusted, including:

When the initial difference is larger than the difference between the value of the performance parameter of any of the single cells and the reference value of the performance parameter, the equalization duty ratio of at least one of the single cells including the single cell is performed Increased adjustment;

When the difference between the value of the performance parameter of any of the single cells and the reference value of the performance parameter is smaller than the initial difference, the equalization duty ratio of at least one of the single cells including the single cell is subtracted Small adjustments.
The method according to any one of claims 1 to 5, wherein when the performance parameter of any of the battery cells in the battery pack satisfies an equalization duty ratio adjustment condition corresponding to the performance parameter, the battery is The equalization duty ratio of at least one of the single cells including the single cell is adjusted in the group, and previously includes:

Determining a single cell in the battery pack that needs to be balanced according to battery information of each unit battery;

For the unit cells that need to be equalized, determining an equalization duty ratio of the unit cells that need to be equalized according to battery information of each unit battery;

For a single cell that does not require equalization, set its equalization duty cycle to a preset value.
The method according to claim 6, wherein the battery information comprises at least one of a voltage value, a current value, and a temperature value;

Determining, according to battery information of each unit battery, an equalization duty ratio of the unit cells that need to be balanced, including:

Obtaining, according to battery information of each unit battery, a value of any one of the following performance parameters of each unit battery: voltage, SOC, internal resistance, self-discharge rate, voltage change rate, power change rate, and time change rate;

Determining a reference value of the target performance parameter according to a value of a target performance parameter of each unit cell, wherein the target performance parameter is any one of the following performance parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change Rate, rate of change of electricity and rate of change of time;

And determining an equalization duty ratio of the unit cells that need to be equalized according to a reference value of the target performance parameter and a value of a target performance parameter of the unit cell that needs to be equalized.
The method of claim 7, wherein the method further comprises:

In the equalization process of the unit cells requiring equalization, when the value of the target performance parameter of the unit cell requiring equalization is different from the reference value of the target performance parameter, the balance is started. When the difference becomes large, an adjustment of the equalization duty ratio of the unit cells that need to be equalized is performed;

In the equalization process of the unit cells requiring equalization, when the value of the target performance parameter of the unit cell requiring equalization is different from the reference value of the target performance parameter, the balance is started. When the difference becomes small, the adjustment of the equalization duty ratio of the unit cells that need to be equalized is reduced.
The method according to claim 7, wherein the target performance parameter is: a voltage;

Determining, according to the reference value of the target performance parameter and the value of the target performance parameter of the unit cell that needs to be equalized, determining an equalization duty ratio of the unit cell that needs to be balanced, including:

Determining the balance of the unit cells that need to be equalized according to the voltage difference between the voltage value of the unit cell that needs to be equalized and the reference voltage value, and the preset correspondence between the voltage difference value and the equalization duty ratio Duty cycle.
The method according to claim 7, wherein the target performance parameter is: a voltage;

Determining, according to the reference value of the target performance parameter and the value of the target performance parameter of the unit cell that needs to be equalized, determining an equalization duty ratio of the unit cell that needs to be balanced, including:

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

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

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

And determining, according to the first SOC value and the second SOC value, an equalization duty ratio of the unit cells that need to be equalized.
The method according to claim 10, wherein the determining the first SOC value corresponding to the reference voltage value according to the reference value of the voltage and the OCV-SOC curve of the reference battery comprises:

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

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

Determining, according to the voltage value of the unit cell that needs to be equalized and the corresponding OCV-SOC curve of the unit cell that needs to be equalized, a second SOC value corresponding to the voltage value of the unit cell that needs to be balanced, include:

Determining an OCV value of the single cell that needs to be equalized according to the voltage value of the unit cell that needs to be equalized and the internal resistance value of the unit cell that needs to be equalized;

And determining, according to the OCV-SOC curve of the unit cell that needs to be equalized, that the SOC value corresponding to the OCV value of the unit cell that needs to be equalized is the second SOC value.
The method according to claim 11, wherein the determining the equalization duty ratio of the unit cells that need to be equalized according to the first SOC value and the second SOC value comprises:

The electric quantity difference is determined according to ΔQ=ΔSOC×C n , wherein ΔQ is the electric quantity difference, ΔSOC is a SOC difference value between the first SOC value and the second SOC value, and C n is the required balance The available capacity of the single battery;

Determining an equalization duty ratio of the unit cells that need to be equalized according to τ=(ΔQ/I)/t, where t is a preset equalization period of the unit cells that need to be equalized, and I is the balance that needs to be balanced. The preset equalization current of the single cell, τ is the equalization duty ratio.
The method according to any one of claims 6 to 12, wherein the determining the battery cells in the battery pack that need to be balanced and requiring equalization comprises:

Obtaining performance parameters of each unit battery according to battery information of each unit of the battery unit obtained during the sampling period of the unit period;

Determining, from the battery pack, the single cell that needs to be equalized according to performance parameters of each of the battery cells in the battery pack, wherein the performance parameter includes at least one of the following parameters: voltage, SOC, and Resistance, self-discharge rate, voltage change rate, power change rate, and time change rate.
A battery equalization system, comprising: an equalization module, an acquisition module, and a control module;

The collecting module is configured to collect battery information of each single battery of the battery pack during a sampling period of a unit period under the control of the control module;

The control module is configured to determine performance parameters of each single battery according to battery information of each single battery of the battery unit acquired during a sampling period of the unit period, where the unit period includes the sampling period and the equalization period; When the performance parameter of any single cell in the group satisfies the equalization duty adjustment condition corresponding to the performance parameter, the equalization duty ratio of at least one single cell including the single cell 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, and the performance parameter includes at least one of the following parameters: voltage, SOC, internal resistance, self-discharge rate, voltage change Rate, rate of change in electricity, and rate of change in time;

The equalization module is configured to balance the cells that need to be equalized during the equalization period under the control of the control module.
The system according to claim 14, wherein the control module is configured to: when the battery pack is in a charging state, a value of a performance parameter of any single battery is greater than or equal to a value corresponding to the performance parameter. When the first preset threshold is used, the adjustment of the equalization duty ratio of the at least one single cell including the single battery in the battery pack is reduced; or

When the battery pack is in a discharged state, when the value of the performance parameter of any of the single cells is less than a second predetermined threshold corresponding to the performance parameter, at least one single cell including the single cell in the battery pack is included The equalization duty ratio of the body battery is adjusted to be reduced.
The system according to claim 15, wherein the performance parameter is a voltage, the first preset threshold is a first preset high threshold or a second preset high threshold, and the second preset high threshold Greater than the first preset high voltage threshold;

The control module is configured to: when the battery pack is in a charging state, a voltage value of any single battery is higher than the first preset high voltage threshold, and balance the at least one single battery including the single battery The adjustment of the duty cycle is reduced;

When the battery pack is in a charging state, the voltage value of any of the single cells is higher than the second predetermined high voltage threshold, and the equalization duty ratio of at least one of the single cells including the single cells is adjusted to zero.
The system according to claim 15, wherein the performance parameter is a voltage, the second predetermined threshold is a first preset low threshold or a second preset low threshold, and the second preset low threshold is Less than the first preset low pressure threshold;

The control module is configured to: when the battery pack is in a discharging state, when the voltage value of any single battery is lower than the first preset low voltage threshold, to at least one single battery including the single battery The adjustment of the equalization duty ratio is performed;

When the battery pack is in a discharged state, when the voltage value of any of the single cells is lower than the second predetermined low-voltage threshold, the equalization duty ratio of at least one of the single cells including the single battery is adjusted to 0. .
The system according to any one of claims 13-17, wherein the control module is configured to compare a value of a performance parameter of any single cell with a difference of a reference value of the performance parameter When the initial difference becomes large, an adjustment of an equalization duty ratio of at least one unit cell including the unit cell is performed;

When the difference between the value of the performance parameter of any of the single cells and the reference value of the performance parameter is smaller than the initial difference, the equalization duty ratio of at least one of the single cells including the single cell is subtracted Small adjustments.
The system according to claim 17, wherein the control module is further configured to determine, according to battery information of each unit battery, a unit cell in the battery pack that needs to be balanced; The body battery determines the equalization duty ratio of the unit cells that need to be equalized according to the battery information of each unit battery; and sets the equalization duty ratio to a preset value for the unit cells that do not need to be equalized.
The system according to claim 14, wherein said control module is connected to an acquisition module and an equalization module corresponding to the same single cell through a channel, and said control module is configured to determine a single connection with the control module When the body battery does not need to be equalized, the control module is controlled to be connected to the corresponding sampling module; or

The control module is further configured to: when the cell connected to the control module needs to be equalized, the acquiring module and the equalization module time-multiplex the channel.
The system according to claim 20, wherein said control module comprises a control chip, said control chip being connected to an acquisition module and an equalization module corresponding to the same single cell through a pin and said one channel.
The system according to claim 14, wherein the control module is respectively connected to the acquisition module and the equalization module corresponding to the same single cell through two channels.
The system according to claim 22, wherein the control module comprises a control chip, and the control chip is respectively connected to an acquisition module and an equalization module corresponding to the same single cell through two pins, the two The pin corresponds to the two channels one by one.
A vehicle characterized by comprising the battery equalization system of any of the preceding claims 14-23.
A computer readable storage medium having stored thereon computer program instructions, wherein the program instructions, when executed by a processor, implement the method of any of claims 1-13.
An electronic device, comprising:

The computer readable storage medium of claim 25;

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