Battery pack capacity control system

Abstract

Provided in the present invention is a battery pack capacity control system, which monitors in real time a battery pack during a discharge process, so as to acquire battery parameters of each battery cell within the battery pack; then, determines an abnormal battery cell within the battery pack on the basis of the battery parameters, controls a switching device to cut off a serial connection between the abnormal battery cell and the battery pack, and connects a bypass battery to the battery pack; and finally, on the basis of historical discharge data of the abnormal battery cell, controls the output of the bypass battery. The present invention solves the problem that the presence of batteries having inconsistent capacities within a battery pack results in the over-discharge of battery cells, solves the problem of over-charge of low-capacity batteries within the battery pack on the basis of the same principle so as to improve the cycle stability of the battery pack and, on the basis of the same principle, also enables the system discharge capacity to be greater than the maximum discharge capacity of an battery cell within the battery pack without causing the over-charge and over-discharge of the batteries.

Description

A capacity control system for a battery pack Technical Field

[0001] The present invention relates to the field of battery management, and in particular to a capacity control system for a battery pack. Background Art

[0002] Modern electronic devices widely use rechargeable batteries as their primary energy source. However, over time, the capacity and performance of batteries gradually degrade, reducing the overall performance of the battery pack. Therefore, when some cells in a battery pack age or become damaged, replacing the entire pack can be costly and impractical.

[0003] To reduce costs and improve resource utilization, batteries with inconsistent capacities are mixed in series battery packs. This means batteries with different lifespans and performance characteristics are used simultaneously in the same battery pack. Differences in capacity, voltage, and internal resistance between batteries with inconsistent capacities can lead to unbalanced charge and discharge, as well as unstable performance. Mixing batteries with inconsistent capacities can reduce overall energy efficiency, affecting the battery pack's operating time and performance.

[0004] In view of this, this application is filed. Technical Solutions

[0005] The present invention discloses a capacity control system for a battery pack, aiming to solve the problem of unbalanced charging and discharging and unstable performance caused by batteries with inconsistent capacities among battery packs.

[0006] An embodiment of the present invention provides a capacity control system for a battery pack, comprising: a battery pack, a bypass battery, a BMS system, and a switching device;

[0007] The input end of the BMS system is electrically connected to the battery pack, the output end of the BMS system is electrically connected to the control end of the switching device, and the bypass battery is electrically connected to the battery pack through the switching device;

[0008] The BMS system is configured to execute a computer program stored therein to implement the following steps:

[0009] monitoring the battery pack in real time during the discharge process to obtain battery parameters of each battery cell in the battery pack;

[0010] determining an abnormal battery cell in the battery pack according to the battery parameters, controlling the switching device to disconnect the abnormal battery cell from the battery pack in series, and connecting the bypass battery to the battery pack;

[0011] The operating time of the bypass battery is determined based on the battery parameters of each battery unit, and the bypass battery is controlled to output.

[0012] Preferably, the determining of the abnormal battery cell in the battery pack according to the battery parameters is specifically:

[0013] Obtaining the SOC value of each battery cell of the battery pack, and calculating the difference between the minimum SOC value and the average SOC value;

[0014] When it is determined that the difference is less than a preset value, the battery cell with the minimum SOC value is identified as an abnormal battery cell.

[0015] Preferably, the determining of the operating time of the bypass battery based on the battery parameters of each battery unit and the controlling of the bypass battery to output are specifically as follows:

[0016] The SOC value of each battery cell of the battery pack is obtained, and the SOC value of each battery cell is calculated based on the working time calculation model to generate the working time of the bypass battery, wherein the expression of the working time calculation model is: ;

[0017] The bypass battery is controlled based on the working time to perform cascade compensation output on abnormal battery cells of the battery pack.

[0018] Preferably, the switching device is a plurality of relays;

[0019] Each battery cell of the battery pack is connected to each other by a set of relay contacts, and the bypass battery is connected to each battery cell of the battery pack in parallel through multiple sets of contacts;

[0020] The contacts are controlled by corresponding relay coils to operate between on and off.

[0021] Preferably, the system further comprises: a temperature detection unit disposed inside the battery pack and the bypass battery, wherein the temperature detection unit is electrically connected to the input end of the BMS system.

[0022] Preferably, it also includes:

[0023] A temperature value collected by the temperature detection unit is obtained, and when it is determined that the temperature value is greater than a preset value, the electrical connection of the battery pack and / or the bypass battery is cut off.

[0024] Preferably, it also includes:

[0025] monitoring the battery pack during charging in real time to obtain battery parameters of each battery cell in the battery pack;

[0026] An abnormal battery cell in the battery pack is determined according to the battery parameters, the switching device is controlled to disconnect the abnormal battery cell from the battery pack in series, and the bypass battery is connected to the battery pack.

[0027] Preferably, determining the abnormal battery cell in the battery pack according to the battery parameters is specifically as follows:

[0028] Obtaining an SOC value of each battery cell of the battery pack, and when the SOC value of the first battery cell reaches 100%, calculating an average SOC value of all battery cells;

[0029] When it is determined that the average SOC value is less than a preset value, the first battery cell whose SOC value reaches 100% is identified as an abnormal battery cell.

[0030] Preferably, the SOC value of each battery cell is calculated by the ampere-hour integration method, wherein the expression of the ampere-hour integration method is: .

[0031] Preferably, the BMS system includes: a main control chip, a first step-down circuit, a second step-down circuit, connection terminals, and a display screen;

[0032] Among them, the input end of the first step-down circuit is electrically connected to the output end of the battery pack, the input end of the second step-down circuit is electrically connected to the output end of the first step-down circuit, the output end of the first step-down circuit is electrically connected to the wiring terminal, the output end of the second step-down circuit is electrically connected to the power supply end of the main control chip, and the main control chip is electrically connected to the display screen through the wiring terminal. Beneficial effects

[0033] The capacity control system for a battery pack provided by the present invention monitors the battery pack in real time during discharge to obtain the battery parameters of each battery cell in the pack. It then identifies abnormal battery cells in the pack based on the battery parameters, controls a switching device to disconnect the abnormal battery cell from the battery pack, and connects a bypass battery to the pack. Finally, based on the historical discharge data of the abnormal battery cell, it controls the output of the bypass battery. This solves the problem of unbalanced charging and discharging and unstable performance caused by inconsistent capacity batteries between battery packs. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic diagram showing the connection relationship between a battery pack, a bypass battery, and a switching device provided in an embodiment of the present invention;

[0035] FIG2 is a schematic diagram of a main control chip and peripheral circuits provided by an embodiment of the present invention;

[0036] FIG3 is a schematic diagram of a step-down circuit provided by an embodiment of the present invention;

[0037] FIG4 is a schematic diagram of the execution steps of a BMS unit provided in an embodiment of the present invention;

[0038] FIG5 is a voltage-capacity diagram of a series-connected battery pack and a single battery provided by an embodiment of the present invention;

[0039] FIG6 is a diagram showing the relationship between voltage and capacity of a series battery pack provided by an embodiment of the present invention, which is provided by compensation and non-compensation;

[0040] FIG7 is experimental data of compensating batteries 1 / 2 / 3 provided by an embodiment of the present invention;

[0041] FIG8 is a schematic diagram showing the effect of bypass battery compensation on the relationship between battery pack voltage and capacity according to an embodiment of the present invention. Modes for Carrying Out the Invention

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0044] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0045] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "an", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0046] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0047] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0048] The "first" and "second" mentioned in the embodiments are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It is understood that the specific order or precedence of "first" and "second" can be interchanged where appropriate. It should be understood that the objects distinguished by "first" and "second" can be interchanged where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0049] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0050] The present invention discloses a capacity control system for a battery pack, aiming to solve the problem of unbalanced charging and discharging and unstable performance caused by batteries with inconsistent capacities among battery packs.

[0051] An embodiment of the present invention provides a capacity control system for a battery pack, comprising: a battery pack, a bypass battery, a BMS system, and a switching device;

[0052] The input end of the BMS system is electrically connected to the battery pack, the output end of the BMS system is electrically connected to the control end of the switching device, and the bypass battery is electrically connected to the battery pack through the switching device;

[0053] It should be noted that the inventors have discovered that in a battery pack, there may be inconsistencies in capacity, voltage and internal resistance between different battery cells. Mixing batteries with inconsistent capacities may lead to reduced overall energy efficiency, affecting the working time and performance of the battery pack.

[0054] In this embodiment, the BMS system is used to monitor the status of each battery cell in the battery pack during the charging and discharging process, and when one of the battery cells is abnormal, the abnormal battery cell is replaced with a bypass battery through the switching device.

[0055] Referring to Figure 1, in one possible embodiment of the present invention, the switching device may be a plurality of relays. Each battery cell in the battery pack is connected to a set of relay contacts, and the bypass battery is connected in parallel to each battery cell in the battery pack via multiple sets of contacts. The contacts are controlled by corresponding relay coils to switch between on and off. It should be noted that the system can precisely switch the contacts by controlling the relay coils, thereby accurately controlling the connection and disconnection of the bypass battery, thereby achieving rapid and accurate switching of the battery pack's operating state.

[0056] Referring to FIG. 2 and FIG. 3 , in a possible embodiment of the present invention, the BMS system may include: a main control chip, a first step-down circuit, a second step-down circuit, connection terminals, and a display screen;

[0057] Among them, the input end of the first step-down circuit is electrically connected to the output end of the battery pack, the input end of the second step-down circuit is electrically connected to the output end of the first step-down circuit, the output end of the first step-down circuit is electrically connected to the wiring terminal, the output end of the second step-down circuit is electrically connected to the power supply end of the main control chip, and the main control chip is electrically connected to the display screen through the wiring terminal.

[0058] It should be noted that in this embodiment, the main control chip can be, but is not limited to, an AT32F403ACGT7. It can collect data from the battery pack and the bypass battery and, after calculation, obtain the voltage, current, internal resistance, SOC value, etc. during operation. The peripheral circuit of the main control chip is connected to a filter circuit, which can be composed of a series of capacitors. These capacitors are used for filtering to ensure that the power supply terminal of the main control chip can obtain a stable 3.3V power supply. It can also be connected to an oscillator to provide a clock signal for the main control chip. It can also be connected to an EEPROM, which is a non-volatile memory for storing configuration data or other long-term data. It can also be connected to an emergency button for operation in an emergency to achieve system interruption. Furthermore, in this embodiment, the first step-down circuit is used to convert the 12V voltage into 5V, which is provided to the terminal block and then powers the display screen. The second step-down circuit is used to convert the 5V voltage into 3.3V, which is used to power the main control chip. Of course, in other embodiments, other methods can be used to generate different voltage levels. This is not specifically limited here, but all such solutions are within the scope of protection of the present invention.

[0059] In one possible embodiment of the present invention, the system further includes a temperature detection unit disposed within the battery pack and the bypass battery, wherein the temperature detection unit is electrically connected to an input terminal of the BMS system. It should be noted that when the main control chip detects abnormal temperature in the battery pack or bypass battery through the temperature detection unit, it can trigger an early warning mechanism or protective measures to prevent battery damage or safety risks caused by the abnormal temperature.

[0060] Referring to FIG. 4 , in this embodiment, the BMS system is configured to execute a computer program stored therein to implement the following steps:

[0061] S101, monitoring the battery pack in real time during a discharge process to obtain battery parameters of each battery cell in the battery pack;

[0062] S102, determining an abnormal battery cell in the battery pack according to the battery parameters, controlling the switching device to disconnect the abnormal battery cell from the battery pack in series, and connecting the bypass battery to the battery pack;

[0063] Specifically, in this embodiment, the process of identifying an abnormal battery cell during discharge is as follows: obtaining the SOC value of each battery cell of the battery pack, and calculating the difference between the minimum SOC value and the average SOC value; when it is determined that the difference is less than a preset value, identifying the battery cell with the minimum SOC value as an abnormal battery cell. Furthermore, in this embodiment, the SOC value of each battery cell can be calculated by, but is not limited to, the ampere-hour integration method, wherein the expression of the ampere-hour integration method is: .

[0064] It should be noted that the SOC value (State of Charge) of each battery cell is used as the basis for abnormality judgment. SOC is a key parameter of the battery charge state. Judging by the difference value helps to find battery cells with large charge state deviations, thereby determining battery cells that may have abnormalities.

[0065] The following is a description using an example of three electronic units. During the discharge process of the battery, the battery cell with the smallest SOC value can be monitored. The minimum SOC value is 10%, while the SOC values ​​of the other battery cells are 16%. The average SOC value of the battery pack is 14%. The difference between the average SOC value and the minimum SOC value of 10% is compared with the preset threshold. The comparison result is used to determine whether the battery cell with the smallest SOC value is an abnormal battery cell.

[0066] S103 , determining the operating time of the bypass battery based on the battery parameters of each battery unit, and controlling the bypass battery to output.

[0067] Specifically, in this embodiment, the SOC value of each battery cell of the battery pack is obtained, and the SOC value of each battery cell is calculated based on the working time calculation model to generate the working time of the bypass battery, wherein the expression of the working time calculation model is: ;

[0068] Controlling the bypass battery to perform cascade compensation output on abnormal battery cells of the battery pack based on the working duration;

[0069] It should be noted that the output power and operating time of the bypass battery are determined based on the SOC value of each battery cell to meet the actual needs of the battery pack and maintain the stability and performance of the battery pack under different workloads. At the same time, the discharge capacity of the battery pack can be higher than the maximum capacity of the battery pack through the cascade compensation method.

[0070] In a possible embodiment of the present invention, it further includes:

[0071] A temperature value collected by the temperature detection unit is obtained, and when it is determined that the temperature value is greater than a preset value, the electrical connection of the battery pack and / or the bypass battery is cut off.

[0072] It should be noted that the temperature detection unit is responsible for real-time monitoring of the temperature of the battery pack and bypass battery. By regularly collecting temperature values, the system accurately understands the temperature changes of the battery pack during operation, including potential temperature increases. The system sets a preset temperature threshold, designed to trigger the protection mechanism before the battery temperature reaches a dangerous level. The preset value takes into account the safe operating range of the battery and possible temperature increases. If the temperature value is determined to be greater than the preset value, the system will quickly and proactively disconnect the battery pack and / or bypass battery, avoiding potential risks caused by excessive temperatures, such as overheating and combustion. By disconnecting the electrical connection, the system effectively prevents battery damage and safety issues that may be caused by high temperatures.

[0073] In a possible embodiment of the present invention, it further includes:

[0074] monitoring the battery pack during charging in real time to obtain battery parameters of each battery cell in the battery pack;

[0075] An abnormal battery cell in the battery pack is determined according to the battery parameters, the switching device is controlled to disconnect the abnormal battery cell from the battery pack in series, and the bypass battery is connected to the battery pack.

[0076] Specifically, in this embodiment, the process of identifying abnormal battery cells during discharge is as follows:

[0077] By monitoring each battery cell in the battery pack, the system obtains its SOC value, or state of charge. When the SOC value of the first battery cell reaches 100%, the system calculates the average SOC value of all battery cells. After calculating the average SOC value, the system compares it with the preset SOC threshold. If the average SOC value is determined to be less than the preset value, the system identifies the battery cell with the first SOC value to reach 100% as an abnormal battery cell. The system conducts a comprehensive analysis of the changing trends of the SOC values ​​to accurately identify battery cells that may have problems.

[0078] The following provides an experimental procedure, specifically the capacity data of a battery pack consisting of three lithium iron phosphate batteries in series. A bypass battery compensation system is formed by connecting a bypass battery in parallel with the battery pack. The battery management system monitors and controls the charge and discharge status of the bypass battery to compensate for aging batteries. See Figure 5 for the voltage-capacity diagram of the series battery pack and a single battery. The discharge capacity data of the series battery pack and a single battery are shown in Table 1 below:

[0079] Table 1

[0080] LFP-1(Ah)LFP-2(Ah)LFP-3(Ah)LFP-4(Ah)LFP-1-2-3-4(Ah)Discharge capacity19.819.819.85.419.8

[0081] Please refer to Figure 6 for the relationship between voltage and capacity of a series battery pack (compensated and non-compensated comparison). The discharge capacity data of a series battery pack is shown in Table 2.

[0082] Table 2

[0083] LFP-1-2-3 (Ah) LFP-1-2-3-4 (Ah) discharge capacity 17.319.8

[0084] Please refer to Table 3, which shows the initial capacity data of three lithium iron phosphate batteries. The released capacity of the battery pack after series connection is shown in Figure 7, which is the experimental data of compensation for batteries 1 / 2 / 3. It can be seen that after the battery pack is connected to the bypass battery, the capacity released by a single battery is compared with the capacity released by the initial single battery. Please combine it with Figure 8, it can be clearly seen that with the bypass battery, the overall battery pack discharge capacity increases, and can reach a discharge capacity close to that of the maximum single battery.

[0085] Table 3

[0086] LFP-1 (Ah) LFP-2 (Ah) LFP-3 (Ah) Charge capacity 17.1 17.2 20.1 Discharge capacity 17.1 17.5 20.2

[0087] In summary, using bypass cells to compensate for aging batteries can significantly improve the performance of the battery pack. The capacity of the compensated aging batteries is relatively stable, reducing capacity loss, and improving the performance of the entire battery pack.

[0088] The capacity control system for a battery pack provided by the present invention monitors the battery pack in real time during discharge to obtain the battery parameters of each battery cell in the pack. It then identifies abnormal battery cells in the pack based on the battery parameters, controls a switching device to disconnect the abnormal battery cell from the battery pack, and connects a bypass battery to the pack. Finally, based on the historical discharge data of the abnormal battery cell, it controls the output of the bypass battery. This solves the problem of unbalanced charging and discharging and unstable performance caused by inconsistent capacity batteries between battery packs.

[0089] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A capacity control system for a battery pack, characterized in that: include: Battery packs, bypass batteries, BMS systems, and switching devices; The input end of the BMS system is electrically connected to the battery pack, the output end of the BMS system is electrically connected to the control end of the switching device, and the bypass battery is electrically connected to the battery pack through the switching device; The BMS system is configured to execute a computer program stored therein to implement the following steps: monitoring the battery pack in real time during the discharge process to obtain battery parameters of each battery cell in the battery pack; determining an abnormal battery cell in the battery pack according to the battery parameters, controlling the switching device to disconnect the abnormal battery cell from the battery pack in series, and connecting the bypass battery to the battery pack; The operating time of the bypass battery is determined based on the battery parameters of each battery unit, and the bypass battery is controlled to output.

2. The capacity control system of a battery pack according to claim 1, characterized in that: The step of determining the abnormal battery cell in the battery pack according to the battery parameters is specifically as follows: Obtaining the SOC value of each battery cell of the battery pack, and calculating the difference between the minimum SOC value and the average SOC value; When it is determined that the difference is less than a preset value, the battery cell with the minimum SOC value is identified as an abnormal battery cell.

3. The capacity control system of a battery pack according to claim 2, characterized in that: The method of determining the operating time of the bypass battery based on the battery parameters of each battery unit and controlling the bypass battery to output power is specifically as follows: The SOC value of each battery cell of the battery pack is obtained, and the SOC value of each battery cell is calculated based on the working time calculation model to generate the working time of the bypass battery, wherein the expression of the working time calculation model is: ； The bypass battery is controlled based on the working time to perform cascade compensation output on abnormal battery cells of the battery pack.

4. The capacity control system of a battery pack according to claim 1, characterized in that: The switching device is a plurality of relays; Each battery cell of the battery pack is connected to each other by a set of relay contacts, and the bypass battery is connected to each battery cell of the battery pack in parallel through multiple sets of contacts; The contacts are controlled by corresponding relay coils to operate between on and off.

5. The capacity control system of a battery pack according to claim 1, characterized in that: Also includes: A temperature detection unit is configured inside the battery pack and the bypass battery, wherein the temperature detection unit is electrically connected to an input terminal of the BMS system.

6. The capacity control system of a battery pack according to claim 5, characterized in that: Also includes: A temperature value collected by the temperature detection unit is obtained, and when it is determined that the temperature value is greater than a preset value, the electrical connection of the battery pack and / or the bypass battery is cut off.

7. The capacity control system of a battery pack according to claim 1, characterized in that: Also includes: monitoring the battery pack during charging in real time to obtain battery parameters of each battery cell in the battery pack; An abnormal battery cell in the battery pack is determined according to the battery parameters, the switching device is controlled to disconnect the abnormal battery cell from the battery pack in series, and the bypass battery is connected to the battery pack.

8. The capacity control system of a battery pack according to claim 7, characterized in that: Determining an abnormal battery cell in the battery pack according to the battery parameters is specifically as follows: Obtaining an SOC value of each battery cell of the battery pack, and when the SOC value of the first battery cell reaches 100%, calculating an average SOC value of all battery cells; When it is determined that the average SOC value is less than a preset value, the first battery cell whose SOC value reaches 100% is identified as an abnormal battery cell.

9. The capacity control system of a battery pack according to claim 2, characterized in that: The SOC value of each battery cell is calculated by the ampere-hour integration method, wherein the expression of the ampere-hour integration method is: .

10. The capacity control system of a battery pack according to claim 1, characterized in that: The BMS system includes: a main control chip, a first step-down circuit, a second step-down circuit, connection terminals, and a display screen; Among them, the input end of the first step-down circuit is electrically connected to the output end of the battery pack, the input end of the second step-down circuit is electrically connected to the output end of the first step-down circuit, the output end of the first step-down circuit is electrically connected to the wiring terminal, the output end of the second step-down circuit is electrically connected to the power supply end of the main control chip, and the main control chip is electrically connected to the display screen through the wiring terminal.

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