Lithium battery equalization method, system and device

Abstract

The invention provides a lithium battery equalization method, system and device, and the method comprises the steps: calculating a voltage difference value Vi between the voltage of each single battery and a minimum value Vmin in the voltages of all single batteries, and determining a to-be-equalized single battery according to the Vi; calculating a difference value SOCm between the SOCm of each single battery to be equalized and the minimum value SOCmin of all the single batteries to be equalized; according to the SOCm, calculating the total current Im of each to-be-equalized single battery to be equalized; and when the equalization condition is met, calculating the real-time equalization current Im of each single battery to be equalized, when Im is greater than Im, starting periodic equalization operation, updating Im = Im-Im every time the equalization operation is performed, repeating the equalization operation for multiple times until Im is close to Im, and ending the equalization operation. According to the invention, the equalization of the single batteries is accurately controlled by calculating the real-time equalization current, so that the equalization of the battery system is more accurate.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and more specifically, to a lithium battery balancing method, system and device. Background Art

[0002] The upper limit of the terminal voltage of lithium batteries is determined by factors such as electrode materials and electrolyte composition. In actual use, multiple battery cells are usually combined in series or parallel to achieve a higher terminal voltage and greater energy. Due to differences in manufacturing processes, materials, etc. between single cells, the capacity, terminal voltage and internal resistance of single cells are inconsistent. During the long-term charging and discharging process, multiple battery cells in the battery pack will become unbalanced, resulting in a decrease in available capacity. For example, the battery with the lowest capacity in a series battery pack will determine the total capacity of the battery pack. In an unbalanced battery pack, when charging, one or more batteries reach the maximum capacity before other batteries. When discharging, batteries that are not fully charged will discharge to the limited capacity before other batteries, causing the battery pack to stop supplying power prematurely due to insufficient voltage. Therefore, when using battery packs in series and parallel, it is necessary to balance the individual batteries in the battery pack.

[0003] At present, battery balancing mainly uses the method of judging whether balancing is needed by judging the ΔSOC of each battery cell, calculating the corresponding capacity difference ΔCAP by judging the ΔSOC of each battery, and then calculating the required balancing time T according to the capacity difference ΔCAP / preset current I.

[0004] The required balancing time T is calculated by the capacity difference ΔCAP. During the balancing process, the single cell voltage will change, and the preset current will also change. Therefore, the calculated required balancing time T is also inaccurate. Summary of the invention

[0005] The present invention aims at the problem of inaccurate lithium battery balancing in the prior art and provides a lithium battery balancing method, system and device.

[0006] According to a first aspect of the present invention, a lithium battery balancing method is provided, which is applied to balancing a plurality of single cells in a battery pack, comprising: Step 1: When the battery pack is in a stationary state, obtain the voltage V of each single cell in the battery pack. i , calculate the minimum value V of each single cell voltage and all single cell voltages min The voltage difference between i , i is the index of the single cell, i is a positive integer; Step 2: According to the voltage difference △V of each single battery i Determine the single battery to be balanced; Step 3: According to the voltage V of each single cell to be balanced m, look up the table to obtain the current remaining power SOC of each single cell to be balanced m , calculate the SOC of each single cell to be balanced m The minimum SOC of all the cells to be balanced min The difference between △SOC m , m is the index of the single cell to be balanced, i is a positive integer; Step 4: According to the difference △SOC of each single cell to be balanced m , calculate the total current △I required for each single cell to be balanced m ; Step 5: When the single cell to be balanced meets the balancing condition, calculate the real-time balancing current I of each single cell to be balanced m , when the △I of the single cell to be balanced m >I m When the periodic balancing operation of the single cell to be balanced is started, each balancing operation is performed to update the total current △I of the single cell to be balanced m =△I m -I m Repeat the equalization operation several times until △I m Close to I m , ending the balancing operation.

[0007] According to a second aspect of the present invention, a lithium battery balancing system is provided, comprising: The acquisition module is used to obtain the voltage V of each single cell in the battery pack when the battery is in a static state. i , calculate the minimum value V of each single cell voltage and all single cell voltages min The voltage difference between i , i is the index of the single cell, i is a positive integer; Determination module, used to determine the voltage difference △V of each single battery i Determine the single battery to be balanced; The calculation module is used to calculate the voltage V of each single cell to be balanced. m , obtain the current remaining power SOC of each single cell to be balanced by looking up the table m , calculate the SOC of each single cell to be balanced m The minimum SOC of all the cells to be balanced min The difference between △SOC m , m is the index of the single cell to be balanced, i is a positive integer; and according to the difference △SOC of each single cell to be balanced m , calculate the total current △I required for each single cell to be balanced m ; The balancing module is used to calculate the real-time balancing current I of each single cell to be balanced when the single cell to be balanced meets the balancing condition. m , when the △I of the single cell to be balanced m >I m When the periodic balancing operation of the single cell to be balanced is started, each balancing operation is performed to update the total current △I of the single cell to be balanced m =△I m -I m Repeat the equalization operation several times until △I m Close to I m , ending the balancing operation.

[0008] According to a third aspect of the present invention, there is provided a lithium battery balancing device, comprising a hardware board, an AFE detection chip and a MUC control unit mounted on the hardware board, wherein the MCU control unit comprises a battery balancing system; The AFE detection chip is used to obtain the voltage V of each single cell in the battery pack when the battery is in a static state. i , sent to the MCU control unit; The MCU control unit is used to call the battery balancing system to perform discharge balancing operations on the single cells to be balanced.

[0009] The present invention provides a lithium battery balancing method, system and device, which calculates the total current △I required to be balanced for each single cell to be balanced. m and real-time balancing current I m , when △I m >I m When the periodic balancing operation is started, each balancing operation is performed to update △I m =△I m -I m Repeat the equalization operation several times until △I m Close to I m The present invention realizes accurate control of the equalization of single cells by calculating the real-time equalization current, so that the battery system is more accurately equalized. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A flow chart of a lithium battery balancing method provided by the present invention; Figure 2 It is a flow chart of the equilibrium strategy; Figure 3 Execute the flow chart for balance; Figure 4 A block diagram of a lithium battery balancing system provided by the present invention; Figure 5A schematic structural diagram of a lithium battery equalization device provided by the present invention. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical features in the various embodiments or single embodiments provided by the present invention can be arbitrarily combined with each other to form a feasible technical solution. This combination is not subject to the constraints of the sequence of steps and / or the structural composition mode, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0012] Figure 1 A flow chart of a lithium battery balancing method provided by the present invention, such as Figure 1 As shown, the method includes: Step 1: When the battery pack is in a stationary state, obtain the voltage V of each single cell in the battery pack. i , calculate the minimum value V of each single cell voltage and all single cell voltages min The voltage difference between i , i is the index of the single cell, i is a positive integer.

[0013] It is understandable that the battery pack includes multiple single cells, and multiple battery packs are connected in series or in parallel. At the end of the battery pack charge and discharge, when the battery is in a static state, the battery balancing judgment is performed. Figure 2 , where when the current of the entire loop of the battery pack is less than the preset current threshold, for example, the current of the entire loop of the battery pack is less than 0.3A, it is determined that the battery pack is in a static state. At this time, the voltage V of each single cell in the battery pack is obtained. i , get the minimum value V among all the single battery voltages min , calculate the voltage V of each single cell i With voltage minimum V min The voltage difference between i .

[0014] Step 2: According to the voltage difference △V of each single battery i Identify the single battery cells to be balanced.

[0015] It is understandable that according to the △V of each single battery iDetermine whether the battery needs to be balanced. For example, if the △V i If it is greater than 15mA, the single cell needs to be balanced, which is referred to as the single cell to be balanced. The serial number of the single cell to be balanced and the serial number N of the single cell with the smallest voltage are recorded.

[0016] Step 3: According to the voltage V of each single cell to be balanced m , obtain the current remaining power SOC of each single cell to be balanced by looking up the table m , calculate the SOC of each single cell to be balanced m The minimum SOC of all the cells to be balanced min The difference between △SOC m , m is the index of the single cell to be balanced, and i is a positive integer.

[0017] It is understandable that a table is maintained, which stores the single cell voltage V i And the current remaining power SOC i According to the voltage V of each single cell to be balanced i , obtain the current remaining power SOC of each single cell to be balanced by looking up the table m , and calculate the SOC of each single cell to be balanced m The minimum SOC of all the cells to be balanced min The difference between △SOC m , m is the index of the single cell to be balanced.

[0018] Step 4: According to the difference △SOC of each single cell to be balanced m , calculate the total current △I required for each single cell to be balanced m .

[0019] Among them, according to the difference △SOC of each single battery to be balanced m , Single cell battery health SOH m 、Battery rated capacity C m And execute the balancing task call cycle T, calculate the total current △I that each single cell to be balanced needs to balance m : △I m =△SOC m ×SOH m ×C m / T.

[0020] Save and record the serial numbers of the single cells to be balanced and the total current that needs to be balanced.

[0021] Step 5: When the single cell to be balanced meets the balancing condition, calculate the real-time balancing current I of each single cell to be balanced m , when the △I of the single cell to be balanced m >I m When the periodic balancing operation of the single cell to be balanced is started, each balancing operation is performed to update the total current △I of the single cell to be balanced m =△I m -I m Repeat the equalization operation several times until △I m Close to I m , ending the balancing operation.

[0022] See also Figure 3 When the single cell to be balanced meets the balancing condition, the balancing operation can be started. The specific method for determining whether the single cell to be balanced meets the balancing condition includes: Get the temperature of the hardware board and each single cell to be balanced. When the temperature of the hardware board is lower than the preset temperature threshold, the temperature of the single cell to be balanced is lower than the preset temperature threshold, and the SOC of the single cell to be balanced is m >When the preset power threshold is reached, the single cell to be balanced meets the balancing condition, wherein the hardware board is equipped with an AFE detection chip, and the voltage V of each single cell is collected by the AFE detection chip i And each single cell temperature T i .

[0023] For example, the temperature of the hardware board is less than 85°C, the temperature of the single battery is less than 58°C, and the SOC of the single battery is m >20%, the single cell to be balanced meets the balancing conditions.

[0024] If the single cell to be balanced meets the balancing condition, the balancing operation starts, and the AFE detection chip performs a discharge balancing operation on the single cell with an excessively high voltage.

[0025] When the cells to be balanced meet the balancing conditions, the voltage V m and the set balancing resistor value R, calculate the real-time balancing current I of each single cell to be balanced m =V m / R. When the △I of the single battery to be balanced m >Real-time balancing current I m When the periodic balancing operation of the single cell to be balanced is started, each balancing operation is performed to update the total current △I of the single cell to be balanced m =△I m -I m Repeat the equalization operation several times until △I m Close to Im , ending the balancing operation.

[0026] Among them, during the balancing operation, if the power is turned off before the balancing of the single cell to be balanced is completed, the total current △I remaining in the single cell to be balanced will be r Stored in the memory, when powered on within a preset time period (for example, within 3 hours), the remaining total current △I of the single battery to be balanced will be completed r If the power is on for more than the preset time period, execute step 1 to re-balance the current of the single battery to be balanced.

[0027] See also Figure 4 , provides a lithium battery balancing system of the present invention, the system comprising: The acquisition module 401 is used to obtain the voltage V of each single cell in the battery pack when the battery is in a stationary state. i , calculate the minimum value V of each single cell voltage and all single cell voltages min The voltage difference between i , i is the index of the single cell, i is a positive integer; The determination module 402 is used to determine the voltage difference △V of each single battery. i Determine the single battery to be balanced; The calculation module 403 is used to calculate the voltage V of each single cell to be balanced. m , obtain the current remaining power SOC of each single cell to be balanced by looking up the table m , calculate the SOC of each single cell to be balanced m The minimum SOC of all the cells to be balanced min The difference between △SOC m , m is the index of the single cell to be balanced, i is a positive integer; and according to the difference △SOC of each single cell to be balanced m , calculate the total current △I required for each single cell to be balanced m ; The balancing module 404 is used to calculate the real-time balancing current I of each single cell to be balanced when the single cell to be balanced meets the balancing condition. m , when the △I of the single cell to be balanced m >I m When the periodic balancing operation of the single cell to be balanced is started, each balancing operation is performed to update the total current △I of the single cell to be balanced m =△I m -I m Repeat the equalization operation several times until △I m Close to I m, ending the balancing operation.

[0028] It can be understood that the lithium battery balancing system provided by the present invention corresponds to the lithium battery balancing method provided by the aforementioned embodiments. The relevant technical features of the lithium battery balancing system can refer to the relevant technical features of the lithium battery balancing method, which will not be repeated here.

[0029] See also Figure 5 , is a schematic diagram of a lithium battery balancing device provided by the present invention, comprising a hardware board, an AFE detection chip and a MUC control unit installed on the hardware board, wherein the MCU control unit includes a battery balancing system; The AFE detection chip is used to obtain the voltage V of each single cell in the battery pack when the battery is in a static state. i , sent to the MCU control unit; The MCU control unit is used to call the battery balancing system to perform discharge balancing operations on the single cells to be balanced.

[0030] It can be understood that the lithium battery balancing device provided by the present invention corresponds to the lithium battery balancing method provided by the aforementioned embodiments. The relevant technical features of the lithium battery balancing device can refer to the relevant technical features of the lithium battery balancing method, which will not be repeated here.

[0031] The embodiment of the present invention provides a lithium battery balancing method, system and device, by calculating the total current △I required to be balanced for each single cell to be balanced m and real-time balancing current I m , when △I m >I m When the periodic balancing operation is started, each balancing operation is performed to update △I m =△I m -I m Repeat the equalization operation several times until △I m Close to I m The present invention realizes accurate control of the equalization of the single cells by calculating the real-time equalization current, so that the battery system is more accurately equalized; and when the power is turned on in a short time, the unfinished equalization operation can be continued.

[0032] It should be noted that in the above embodiments, the description of each embodiment has its own emphasis, and for parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0033] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0034] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded computer, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0035] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0036] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0037] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0038] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A lithium battery balancing method, applied to balancing multiple single cells in a battery pack, characterized in that: include: Step 1: When the battery pack is in a stationary state, obtain the voltage V of each single cell in the battery pack. i , calculate the minimum value V of each single cell voltage and all single cell voltages min The voltage difference between i , i is the index of the single cell, i is a positive integer; Step 2: According to the voltage difference △V of each single battery i Determine the single battery to be balanced; Step 3: According to the voltage V of each single cell to be balanced m , obtain the current remaining power SOC of each single cell to be balanced by looking up the table m , calculate the SOC of each single cell to be balanced m The minimum SOC of all the cells to be balanced min The difference between △SOC m , m is the index of the single cell to be balanced, i is a positive integer; Step 4: According to the difference △SOC of each single cell to be balanced m , calculate the total current △I required for each single cell to be balanced m ; Step 5: When the single cell to be balanced meets the balancing condition, calculate the real-time balancing current I of each single cell to be balanced m , when the △I of the single cell to be balanced m >I m When the periodic balancing operation of the single cell to be balanced is started, each balancing operation is performed to update the total current △I of the single cell to be balanced m =△I m -I m Repeat the equalization operation several times until △I m Close to I m , ending the balancing operation.

2. The lithium battery equalization method according to claim 1, characterized in that: In step 2, according to the voltage difference △V of each single battery i Determine the single battery to be balanced, including: If the single battery voltage V i If the voltage of the battery is greater than the preset voltage threshold, the battery is a battery to be balanced.

3. The lithium battery equalization method according to claim 1, characterized in that: In step 3, according to the voltage V of each single cell to be balanced m , obtain the current remaining power SOC of each single cell to be balanced by looking up the table m , previously also included: Maintain a table that stores the single cell voltage V i And the current remaining power SOC i The corresponding relationship.

4. The lithium battery equalization method according to claim 1, characterized in that: In step 4, according to the difference △SOC of each single battery to be balanced m , calculate the total current △I required for each single cell to be balanced m ,include: △I m =△SOC m ×SOH m ×C m / T; Among them, SOH m is the battery health, C m is the rated capacity of the battery, and T is the call cycle for executing the balancing task.

5. The lithium battery equalization method according to claim 1, characterized in that: Determine whether the single battery to be balanced meets the balancing conditions, including: Get the temperature of the hardware board and each single cell to be balanced. When the temperature of the hardware board is lower than the preset temperature threshold, the temperature of the single cell to be balanced is lower than the preset temperature threshold, and the SOC of the single cell to be balanced is m >When the preset power threshold is reached, the single cell to be balanced meets the balancing condition, wherein the hardware board is equipped with an AFE detection chip, and the voltage V of each single cell is collected by the AFE detection chip i And each single cell temperature T i .

6. The lithium battery equalization method according to claim 1, characterized in that: In step 5, the real-time balancing current I of each single cell to be balanced is calculated. m ,include: According to the voltage V of each single battery to be balanced m and the set balancing resistor value R, calculate the real-time balancing current I of each single cell to be balanced m =V m / R.

7. The lithium battery equalization method according to claim 1, characterized in that: The step 5 further includes: If the power is turned off before the balancing of the single cell to be balanced is completed, the total current △I remaining in the single cell to be balanced will be r Stored in the memory, when powered on within the preset time period, the remaining total current △I of the single battery to be balanced will be completed r If the power is on for more than the preset time period, execute step 1 to re-balance the current of the single battery to be balanced.

8. The lithium battery equalization method according to claim 1, characterized in that: In the step 1, determining that the battery is in a stationary state includes: When the current of the entire loop of the battery pack is less than a preset current threshold, it is determined that the battery pack is in a stationary state.

9. A lithium battery equalization system, characterized in that: include: The acquisition module is used to obtain the voltage V of each single cell in the battery pack when the battery is in a static state. i , calculate the minimum value V of each single cell voltage and all single cell voltages min The voltage difference between i , i is the index of the single cell, i is a positive integer; Determination module, used to determine the voltage difference △V of each single battery i Determine the single battery to be balanced; The calculation module is used to calculate the voltage V of each single cell to be balanced. m , obtain the current remaining power SOC of each single cell to be balanced by looking up the table m , calculate the SOC of each single cell to be balanced m The minimum SOC of all the cells to be balanced min The difference between △SOC m , m is the index of the single cell to be balanced, i is a positive integer; And according to the difference △SOC of each single battery to be balanced m , calculate the total current △I required for each single cell to be balanced m ; The balancing module is used to calculate the real-time balancing current I of each single cell to be balanced when the single cell to be balanced meets the balancing condition. m , when the △I of the single cell to be balanced m >I m When the periodic balancing operation of the single cell to be balanced is started, each balancing operation is performed to update the total current △I of the single cell to be balanced m =△I m -I m Repeat the equalization operation several times until △I m Close to I m , ending the balancing operation.

10. A lithium battery equalization device, characterized in that: It comprises a hardware board, an AFE detection chip and a MUC control unit installed on the hardware board, wherein the MCU control unit comprises the lithium battery balancing system according to claim 9; The AFE detection chip is used to obtain the voltage V of each single cell in the battery pack when the battery is in a static state. i , sent to the MCU control unit; The MCU control unit is used to call the lithium battery balancing system to perform discharge balancing operations on the single cells to be balanced.

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