A multi-dimensional balancing method, system, medium and device for power batteries

Abstract

The present invention belongs to the technical field of electric vehicle power battery systems and provides a multi-dimensional balancing method, system, medium and device for power batteries. The method includes obtaining the voltage information, current information and static time information of each string of cells in the power battery when the system is powered on, and then comparing them with the corresponding preset thresholds to determine whether the static balancing condition is met; when the static balancing condition is met, the balancing time and the number of cell strings are updated in combination with the SOC-OCV curve, and recorded as the first balancing information; when the static balancing condition is not met, it is determined whether the remaining balancing time in the first balancing information is zero. If and only if the remaining balancing time in the first balancing information is zero, and if the slow charging balancing condition is met, slow charging balancing is enabled and the number of strings with cell voltages higher than the set voltage threshold is recorded as the second balancing information.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric vehicle power battery systems, and in particular relates to a multi-dimensional balancing method, system, medium and equipment for power batteries. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Power batteries are the power source of electric vehicles and determine the safety and reliability of the entire vehicle. Power batteries are composed of hundreds or even thousands of individual cells. Due to product consistency variations during the production process, different cells in the same system can have varying self-discharge rates. Over time, these variations in self-discharge rates can cause differences in the state of charge (SOC) of different cells. This not only impacts the customer experience, such as reduced battery life, but can also lead to issues such as disposal.

[0004] The inventors discovered that currently, balancing solutions are used to mitigate the impact of self-discharge rate. However, due to the long voltage plateau period of lithium iron phosphate batteries, existing balancing solutions cannot accurately determine the charge state of each battery cell, avoid the gradual increase in consistency differences between different battery cells, and cannot effectively identify and balance them in time, resulting in a significant reduction in battery life or failures such as vehicle abandonment. Summary of the Invention

[0005] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a multi-dimensional balancing method, system, medium and device for a power battery, which can accurately determine the charge state of each battery cell.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A first aspect of the present invention provides a multi-dimensional balancing method for a power battery.

[0008] A multi-dimensional balancing method for a power battery, comprising:

[0009] Obtain the voltage, current, and rest time information of each string of cells in the power battery when the system is powered on, and then compare them with the corresponding preset thresholds to determine whether the static balance condition is met;

[0010] When the static equilibrium condition is reached, the equilibrium time and the number of battery cell strings are updated in combination with the SOC-OCV curve and recorded as the first equilibrium information;

[0011] When the static balancing condition is not met, determine whether the remaining balancing time in the first balancing information is zero. When and only when the remaining balancing time in the first balancing information is zero and the slow charging balancing condition is met, start slow charging balancing and record the number of strings with single cell voltage higher than the set voltage threshold as the second balancing information.

[0012] Among them, the static balancing condition has a higher priority than the slow charging balancing condition.

[0013] As an implementation manner, when the remaining equalization time in the first equalization information is not zero, static equalization is continued to be performed and the system equalization information is updated.

[0014] As an implementation manner, when the number of times that the highest voltage of a cell does not reach above a preset voltage threshold during the accumulated slow charging process reaches a set number, the second balancing information stored in the system is cleared.

[0015] As an implementation method, if the static equilibrium condition is reached, the equilibrium information stored in the system is immediately updated.

[0016] A second aspect of the present invention provides a multi-dimensional balancing system for a power battery.

[0017] A multi-dimensional balancing system for a power battery, comprising:

[0018] A static balancing condition judgment module is used to obtain the voltage information, current information, and rest time information of each string of cells in the power battery when the system is powered on, and then compare them with the corresponding preset thresholds to determine whether the static balancing condition is met;

[0019] A first balancing information recording module is used to update the balancing time and the number of battery cell strings in combination with the SOC-OCV curve when the static balancing condition is reached, and record the update as the first balancing information;

[0020] The slow charge balancing condition judgment module is used to judge whether the remaining balancing time in the first balancing information is zero when the static balancing condition is not met. When and only when the remaining balancing time in the first balancing information is zero and the slow charge balancing condition is met, the slow charge balancing is turned on and the number of strings with single cell voltage higher than the set voltage threshold is recorded as the second balancing information.

[0021] As an implementation manner, when the remaining equalization time in the first equalization information is not zero, static equalization is continued to be performed and the system equalization information is updated.

[0022] As an implementation manner, when the number of times that the highest voltage of a cell does not reach above a preset voltage threshold during the accumulated slow charging process reaches a set number, the second balancing information stored in the system is cleared.

[0023] As an implementation method, if the static equilibrium condition is reached, the equilibrium information stored in the system is immediately updated.

[0024] A third aspect of the present invention provides a computer-readable storage medium.

[0025] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the multi-dimensional balancing method for power batteries as described above.

[0026] A fourth aspect of the present invention provides a computer device.

[0027] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps in the multi-dimensional balancing method for power batteries as described above are implemented.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention uses a multi-dimensional balancing technique by judging static balancing conditions and slow charging balancing conditions, so that the power battery can obtain more balancing opportunities during actual use, thereby improving the balancing effect of the power battery;

[0030] (2) The present invention sets the slow charge balancing to be enabled only when and only when the remaining balancing time in the first balancing information is zero and the slow charge balancing condition is met, and the static balancing condition has a higher priority than the slow charge balancing condition. This technical means of adding priority judgment to multi-dimensional balancing can reduce the impact of battery misbalancing;

[0031] (3) The present invention adopts the method of recording only the number of strings balanced without calculating the time of balancing for the charging terminal, which can effectively avoid the problem of misbalancing caused by inaccurate judgment of the charge state during the charging and discharging process; the present invention adopts the method of increasing the number of times of balancing at the charging terminal to effectively reduce the risk of over-balancing caused by long-term customers' insufficient charge.

[0032] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0034] Figure 1 A flow chart of a multi-dimensional balancing method for a power battery provided by an embodiment of the present invention;

[0035] Figure 2 This is the SOC-OCV curve of a certain lithium iron phosphate;

[0036] Figure 3 A comparison chart of the vehicle's terminal charging voltage and OCV curve at low SOC. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0038] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] Explanation of terms:

[0041] SOC - battery state of charge;

[0042] OCV--open circuit voltage curve.

[0043] The OCV curve after the battery has been fully rested (more than 2 hours) can intuitively and accurately reflect the SOC status, but the lithium iron phosphate platform area is relatively wide, and the corresponding OCV difference is more obvious only when the SOC of a single battery is relatively low. Therefore, the SOC difference between different cells in the same system is usually judged mainly when the SOC value is low. Since most users of new energy vehicles take mileage anxiety into consideration when using them, they usually recharge when the SOC is high, and the opportunities for long-term rest (more than 2 hours) when the SOC is low are even rarer. After long-term use, since it is rarely possible to accurately judge the difference in consistency between different cells, the consistency difference between different cells gradually increases and cannot be effectively identified and balanced in time, which may lead to a significant reduction in battery life or failures such as vehicle abandonment. Based on this situation, the present invention designs a multi-dimensional balancing method for power batteries and establishes priorities. When the vehicle reaches the static OCV identification area, the balancing information can be judged and recorded in time. When the vehicle has not reached this condition, the voltage distribution when the charging terminal current is less than or equal to the preset current threshold (such as 0.2C) is used to balance some battery cells with voltages higher than a preset voltage threshold (such as 3.5V).

[0044] Example 1

[0045] Reference Figure 1 This embodiment provides a multi-dimensional balancing method for a power battery, which includes:

[0046] Obtain the voltage, current, and rest time information of each string of cells in the power battery when the system is powered on, and then compare them with the corresponding preset thresholds to determine whether the static balance condition is met;

[0047] When the static equilibrium condition is reached, the equilibrium time and the number of battery cell strings are updated in combination with the SOC-OCV curve and recorded as the first equilibrium information;

[0048] When the static balancing condition is not met, determine whether the remaining balancing time in the first balancing information is zero. When and only when the remaining balancing time in the first balancing information is zero and the slow charging balancing condition is met, start slow charging balancing and record the number of strings with single cell voltage higher than the set voltage threshold as the second balancing information.

[0049] As attached Figure 2 As shown in the figure, the SOC is in the platform area in the range of 25% to 95%, and the voltage difference is very small. Considering the influence of acquisition error, it is impossible to accurately estimate the difference in charge state between cells in this area. When the voltage is ≤3.273V, the voltage difference is obvious as the SOC changes. Figure 3 The V threshold in step 1 is set to 3.273V. Static conditions are generally considered to be met when the current remains below 2A for at least 2 hours, so T can be set to 2 hours. When the current (I ≤ 2A) && (time t ≥ 2 hours) and Vmin < 3.273V are reached, the SOC difference between the other cells and the lowest cell is obtained by looking up the table based on the cell's SOC-OCV curve. The balancing time Tx for each string except the lowest string is calculated by combining the balancing current and duty cycle. To avoid misbalancing or overbalancing, the smaller of the calculated Tx and the static t (100 hours) is recorded as the first balancing information exp1.

[0050] The static balancing condition takes precedence over the slow charging balancing condition. If the static balancing condition is met, all balancing information stored in the system is updated immediately. Even if the system already has balancing information stored, it will be overwritten with the latest balancing information.

[0051] When the remaining equalization time in the first equalization information is not zero, static equalization is continued and the system equalization information is updated.

[0052] When the number of times that the maximum voltage of a single cell does not reach above the preset voltage threshold during the accumulated slow charging process reaches a set number, the second balancing information stored in the system is cleared.

[0053] In the specific implementation process, a certain margin is reserved for the equalization time to avoid mis - equalization.

[0054] If the static equalization condition is not met, check whether the first equalization information exp1 recorded last time by the system has been completed. If it has not been completed, continue to execute the first equalization information exp1. If the first equalization information exp1 is empty or the first equalization information exp1 recorded previously has been completed, then judge whether the slow - charge equalization judgment condition is met, as shown in steps 3 to 6 in Figure 1 where the slow - charge equalization judgment condition is that the single - cell voltage ≥ 3.5V and the charging current 5A < I ≤ 0.2C (C is the nominal capacity of the corresponding battery). When this condition is met, record the number of strings with a single - cell voltage higher than 3.5V, which is recorded as the second equalization information exp2. The second equalization information exp2 does not need to record the equalization time. The reason for not recording the equalization time here is that under dynamic conditions, the accurate value of the SOC difference between battery cells cannot be truly determined, but it can qualitatively determine which strings of single - cells are high and low. At the same time, to avoid mis - equalization or over - equalization, when the number of times the highest single - cell voltage does not reach above 3.5V during the cumulative slow charge reaches 5 times, clear the exp2 information stored in the system.

[0055] In this embodiment, the equalization start conditions are as follows: the lowest single - cell voltage reaches above 3.0V; exp1 or exp2 in the system is not completed; the vehicle system is operating normally.

[0056] As Figure 3 shown in the voltage distribution at the end of charging and the OCV distribution curve at low SOC, it can be seen that the single - cells with a voltage higher than 3.5V at the end of charging are strings 6 / 10 / 13 / 19 / 29 / 30 / 37, and the SOC of these strings is also higher than the lowest string when the system power is relatively low. Therefore, when the system has not reached the exp1 equalization condition for a long time, passive discharge equalization of these strings will improve the system consistency difference to a certain extent.

[0057] Embodiment 2

[0058] This embodiment provides a multi - dimensional equalization system for power batteries, which specifically includes the following modules:

[0059] (1) Static equalization condition judgment module, which is used to obtain the voltage information, current information, and static time information of each string of battery cells in the power battery when the system is powered on, and then compare them with the corresponding preset thresholds to judge whether the static equalization condition is met;

[0060] (2) First equalization information recording module, which is used to update the equalization time and the number of battery - cell strings in combination with the SOC - OCV curve and record it as the first equalization information when the static equalization condition is met;

[0061] (3) A slow charge balancing condition judgment module, which is used to judge whether the remaining balancing time in the first balancing information is zero when the static balancing condition is not met. When and only when the remaining balancing time in the first balancing information is zero and the slow charge balancing condition is met, the slow charge balancing is turned on and the number of strings with single cell voltages higher than the set voltage threshold is recorded as the second balancing information.

[0062] In a specific implementation process, when the remaining equalization time in the first equalization information is not zero, static equalization is continued to be performed and the system equalization information is updated.

[0063] When the number of times that the maximum voltage of a single cell does not reach above a preset voltage threshold during the accumulated slow charging process reaches a set number, the second balancing information stored in the system is cleared.

[0064] If the static equilibrium condition is reached, the equilibrium information stored in the system is updated immediately.

[0065] It should be noted here that the various modules in this embodiment correspond one-to-one to the various steps in Example 1, and the specific real-time processes are the same, which will not be repeated here.

[0066] Example 3

[0067] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the steps in the multi-dimensional balancing method for power batteries as described above are implemented.

[0068] Example 4

[0069] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps in the multi-dimensional balancing method for power batteries described above are implemented.

[0070] 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 flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, 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 processor 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 flowcharts and / or block diagrams. 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.

[0071] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A multi-dimensional balancing method for a power battery, characterized in that: include: Obtain the voltage, current, and rest time information of each string of cells in the power battery when the system is powered on, and then compare them with the corresponding preset thresholds to determine whether the static balance condition is met; When the static equilibrium condition is reached, the equilibrium time and the number of battery cell strings are updated in combination with the SOC-OCV curve and recorded as the first equilibrium information; When the static balancing condition is not met, determine whether the remaining balancing time in the first balancing information is zero. If and only if the remaining balancing time in the first balancing information is zero and the slow charge balancing condition is met, start slow charge balancing and record the number of strings with single cell voltages higher than the set voltage threshold as the second balancing information. Static balancing conditions have a higher priority than slow charging balancing conditions. If static balancing conditions are met, all balancing information stored in the system will be updated immediately. Even if the system has already stored balancing information, it will be overwritten with the latest balancing information. When the number of times that the maximum voltage of a single cell does not reach above the preset voltage threshold during the accumulated slow charging process reaches a set number, the second balancing information stored in the system is cleared.

2. The multi-dimensional balancing method for power batteries according to claim 1, characterized in that: When the remaining equalization time in the first equalization information is not zero, static equalization is continued and the system equalization information is updated.

3. The multi-dimensional balancing method for power batteries according to claim 1, characterized in that: If the static equilibrium condition is reached, the equilibrium information stored in the system is updated immediately.

4. A multi-dimensional balancing system for power batteries, characterized in that: include: A static balancing condition judgment module is used to obtain the voltage information, current information, and rest time information of each string of cells in the power battery when the system is powered on, and then compare them with the corresponding preset thresholds to determine whether the static balancing condition is met; A first balancing information recording module is used to update the balancing time and the number of battery cell strings in combination with the SOC-OCV curve when the static balancing condition is reached, and record the update as the first balancing information; A slow charge balancing condition judgment module is used to determine whether the remaining balancing time in the first balancing information is zero when the static balancing condition is not met. If and only if the remaining balancing time in the first balancing information is zero and the slow charge balancing condition is met, slow charge balancing is enabled and the number of strings with cell voltages higher than the set voltage threshold is recorded as the second balancing information. Static balancing conditions have a higher priority than slow charging balancing conditions. If static balancing conditions are met, all balancing information stored in the system will be updated immediately. Even if the system has already stored balancing information, it will be overwritten with the latest balancing information. When the number of times that the maximum voltage of a single cell does not reach above the preset voltage threshold during the accumulated slow charging process reaches a set number, the second balancing information stored in the system is cleared.

5. The multi-dimensional balancing system for power batteries according to claim 4, characterized in that: When the remaining equalization time in the first equalization information is not zero, static equalization is continued and the system equalization information is updated.

6. The multi-dimensional balancing system for power batteries according to claim 4, characterized in that: If the static equilibrium condition is reached, the equilibrium information stored in the system is updated immediately.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the multi-dimensional balancing method for a power battery as claimed in any one of claims 1 to 3 are implemented.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the multi-dimensional balancing method for a power battery as claimed in any one of claims 1 to 3 are implemented.

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