Control method and system of active equalization lithium iron phosphate hybrid battery device

Abstract

The invention discloses a control method and system for an active equalization lithium iron phosphate hybrid battery device. The method comprises the following steps: full charge correction triggering: starting an active equalization program when the SOC of a battery pack reaches a threshold value; a low-current active equalization strategy is adopted, and charges are continuously transferred; performing dynamic voltage difference threshold control and real-time monitoring: acquiring the voltage of each single battery at intervals, calculating the voltage standard deviation sigma in the module, and if the voltage standard deviation sigma is greater than 30mV, judging that abnormal voltage difference exists; grading response: when the voltage difference between the single batteries exceeds 50mV, immediately stopping the equalization operation, and triggering an overvoltage / undervoltage protection mechanism; and when the voltage difference is between 30mV and 50mV, the equalizing current is reduced to 0.02 C, and if the voltage difference is not recovered to a safe range, the equalizing operation is terminated. According to the method, the active equalization program can be accurately started, capacity calibration is carried out to correct the capacity deviation, and meanwhile, the voltage difference of each single battery is synchronously monitored, so that the equalization efficiency and precision of the battery pack are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery management and energy storage, and relates to a control method and system for an active balancing lithium iron phosphate hybrid battery device. Background Art

[0002] As a high-performance energy storage device, lithium iron phosphate batteries have been widely used in recent years in fields such as electric vehicles, renewable energy systems, and portable energy storage devices. However, during the actual use of lithium iron phosphate hybrid batteries, their voltage characteristics have posed a series of challenges, especially in the aspect of battery state estimation (SOC, i.e., State of Charge, the percentage of remaining battery charge). Lithium iron phosphate batteries have a significant voltage plateau characteristic, that is, during the charging and discharging processes of the battery, the voltage remains relatively stable within a certain range and does not fluctuate significantly with the significant change of SOC. This characteristic makes it difficult to accurately judge the true SOC range of the battery through simple voltage sampling methods. Specifically, when the battery is in the intermediate stage of 25% to 98% SOC, its open circuit voltage (OCV) presents a plateau state, and the voltage change is not obvious, making it impossible to directly judge the SOC value of the battery by measuring the voltage.

[0003] To address this challenge, SOC correction algorithms have been introduced in the existing technical system, and "SOC-OCV correction" is a common method. This method estimates the SOC value of the battery by measuring the open circuit voltage (OCV) of the battery under no-load conditions and based on the mapping relationship between OCV and SOC. However, its effect is relatively good in the low SOC interval and the full charge stage, and can accurately and uniquely determine the SOC value, but there is a large uncertainty in the intermediate stage of SOC. In particular, for the full charge correction of lithium iron phosphate batteries, the existing algorithms and devices have the problem of being less intelligent. Due to the limitation of hardware accuracy in the battery management system (BMS) when collecting current information, there will be errors in the process of calculating SOC using the "ampere-hour integration method". The long-term accumulated errors will lead to the phenomenon of overestimated or underestimated SOC, thus affecting the normal use of the battery. In addition, the triggering conditions and execution process of full charge correction are relatively complex. The battery needs to be left standing for a period of time after full charge to wait for the depolarization process of the battery cells to complete before accurately measuring the OCV and performing SOC correction.

[0004] Therefore, in view of the voltage plateau characteristic of lithium iron phosphate batteries and the difficulty of SOC estimation, there is an urgent need to develop a more intelligent and accurate full charge correction algorithm and device. This can not only improve the accuracy of battery state estimation, but also extend the service life of the battery and enhance the overall performance and safety of the battery system. Summary of the Invention

[0005] The object of the present invention is to solve the problem that the estimation of the percentage of the remaining battery power of a lithium iron phosphate battery in the prior art is inaccurate due to the voltage platform characteristics during use, and to provide a control method and system for an active equalization lithium iron phosphate hybrid battery device.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A control method for an active equalization lithium iron phosphate hybrid battery device includes the following steps:

[0008] Full charge correction trigger: After the SOC of the lithium iron phosphate battery pack reaches or exceeds 99%, start the active equalization program. First, calibrate the capacity through a coulomb meter to correct the capacity deviation, and simultaneously monitor the voltage differences of each single battery.

[0009] Long-term equalization: Adopt a low-current active equalization strategy, where the equalization current does not exceed 0.05 times the rated capacity of the battery, and continuously transfer charges through a flying capacitor or a bidirectional DC-DC conversion topology.

[0010] Dynamic voltage difference threshold control:

[0011] Real-time monitoring: Collect the voltages of each single battery at intervals, calculate the standard deviation σ of the voltages within the module. If the standard deviation σ of the voltages is greater than 30 mV, it is determined that there is an abnormal voltage difference.

[0012] Hierarchical response: When the voltage difference between single batteries exceeds 50 mV, immediately stop the equalization operation and trigger the overvoltage / undervoltage protection mechanism; when the voltage difference between single batteries is between 30 mV and 50 mV, reduce the equalization current to 0.02C and continuously monitor. If the voltage difference does not return to the safe range, terminate the equalization operation.

[0013] After the SOC of the lithium iron phosphate battery pack reaches or exceeds 99%, calibrate the coulomb meter to accurately record the capacity information of the battery, and measure and record the initial voltage distribution of each single battery; then start the active equalization program and set the initial equalization current to 0.05 times the rated capacity of the battery.

[0014] The calibration of the coulomb meter to accurately record the capacity information of the battery and the measurement and recording of the initial voltage distribution of each single battery are specifically as follows:

[0015] The battery management system BMS detects the SOC state of the battery pack.

[0016] When the state of charge (SOC) reaches or exceeds 99%, the battery management system (BMS) initiates the calibration procedure of the coulomb meter. Through current detection and integration calculations, it ensures the accuracy of the battery capacity information recorded by the coulomb meter. The calibration process takes into account the temperature effect of the battery and the comparison between the charge and discharge amounts recorded by the coulomb meter and the actual measured changes in battery voltage.

[0017] Measure and record the initial voltage distribution: The battery management system (BMS) detects the voltage of each single battery in the battery pack one by one, through a voltage sensor or an analog-to-digital converter.

[0018] Record the voltage value of each detected single battery to form an initial voltage distribution map.

[0019] During the long-term equalization, specifically:

[0020] Use a flying capacitor or a bidirectional DC-DC conversion topology as the medium for charge transfer. By controlling the switching of switches or adjusting the output voltage and current of the bidirectional DC-DC converter, continuous and stable energy transfer between single batteries in the battery pack is achieved.

[0021] During the equalization process, detect the voltage of each single battery in the battery pack and issue an equalization signal based on the detected voltage difference to control the corresponding switch switching or adjust the output of the bidirectional DC-DC converter to compensate for the small voltage difference caused by self-discharge or internal resistance differences.

[0022] The equalization time is set to 2 to 4 hours to ensure that the voltage difference in the battery pack is fully compensated, while avoiding excessive stress or damage to the battery.

[0023] The flying capacitor type equalization circuit uses an equalization capacitor as the carrier for energy transfer. By controlling the switching of switches, it switches between the highest voltage cell and the lowest voltage cell to achieve energy absorption and release.

[0024] The bidirectional DC-DC conversion topology adopts modular equalization. Each single battery or a group of batteries is connected to other batteries through a bidirectional DC-DC converter to achieve bidirectional energy transfer. By continuously adjusting the output of the bidirectional DC-DC converter, the voltage difference in the battery pack is gradually reduced.

[0025] The real-time monitoring specifically updates the standard deviation σ of the voltages of each single battery in the battery module every 5 minutes to evaluate the uniformity of the voltage distribution. If the standard deviation σ of the voltage is less than 30 mV, the current equalization current and equalization strategy are maintained unchanged, and the equalization operation continues. If the standard deviation σ of the voltage is greater than or equal to 30 mV, a dynamic adjustment mechanism is triggered, and measures such as reducing the equalization current to a lower level or pausing the equalization operation are taken according to the degree of voltage difference, and the positions of the single batteries with abnormal voltages are recorded for subsequent analysis and processing.

[0026] The termination of the equalization operation specifically means that the equalization operation is terminated when any of the following conditions is met:

[0027] The preset equalization duration is reached, and at the end of this equalization duration, the standard deviation σ of the voltages of each single battery in the battery module is less than 20 mV, indicating that the voltage distribution has reached a sufficiently uniform state;

[0028] Or during the equalization process, it is detected that the voltage of any single battery exceeds the preset safe range. At this time, to protect the battery from damage, the equalization operation is immediately terminated.

[0029] A control system for an active equalization lithium iron phosphate hybrid battery device includes the following modules:

[0030] Full charge correction trigger module: used to start the active equalization program when the state of charge (SOC) value of the lithium iron phosphate battery pack reaches or exceeds 99%;

[0031] Long-term equalization control module: adopts a low-current active equalization strategy, where the equalization current does not exceed 0.05 times the rated capacity of the battery;

[0032] Dynamic pressure difference threshold control module:

[0033] Real-time monitoring unit: used to collect the voltages of each single battery at intervals and calculate the standard deviation σ of the voltages in the module; when the standard deviation σ of the voltage is greater than 30 mV, it is determined that there is an abnormal voltage difference;

[0034] Hierarchical response unit: performs hierarchical response according to the pressure difference between single batteries:

[0035] When the pressure difference exceeds 50 mV, the equalization operation is immediately stopped, and the overvoltage / undervoltage protection mechanism is triggered;

[0036] When the pressure difference is between 30 mV and 50 mV, the equalization current is reduced to 0.02 times the rated capacity of the battery, and continuous monitoring is carried out; if the pressure difference does not return to the safe range within the specified time, the equalization operation is terminated.

[0037] The full charge correction trigger module further includes a capacity calibration unit, which calibrates the capacity through a coulomb meter to correct the capacity deviation and simultaneously monitors the voltage differences of each single cell.

[0038] The long-term equalization control module is configured with a charge transfer unit, which realizes continuous charge transfer through a flying capacitor or a bidirectional DC-DC conversion topology.

[0039] It also includes:

[0040] Communication and decision center: responsible for data communication and instruction issuance between modules, including receiving data from the real-time monitoring unit, and triggering full charge correction, adjusting the equalization current, executing stop equalization or triggering protection mechanism instructions according to preset algorithms or logical judgments;

[0041] Protection mechanism execution module: responds to the instructions of the hierarchical response unit and executes overvoltage / undervoltage protection measures to ensure the safe operation of the battery pack.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] A control method for an active equalization lithium iron phosphate hybrid battery device in the present invention can accurately start the active equalization program after the SOC of the lithium iron phosphate battery pack reaches or exceeds 99%, and perform capacity calibration to correct the capacity deviation. At the same time, it synchronously monitors the voltage differences of each single cell, thereby significantly improving the equalization efficiency and accuracy of the battery pack. In addition, a low-current active equalization strategy is adopted to avoid battery damage that may be caused by high-current equalization, ensuring the stability and continuity of the equalization process. The dynamic pressure difference threshold control mechanism can real-time monitor the voltage differences of each single cell and perform hierarchical response according to the size of the pressure difference, effectively avoiding the problem of overcharge / overdischarge of single cells caused by continuous equalization, and significantly improving the safety and stability of the battery pack. When the pressure difference between single cells exceeds the preset threshold, the equalization operation is immediately stopped and the protection mechanism is triggered to prevent safety accidents caused by voltage imbalance of the battery pack.

[0044] It supports integration with the existing BMS system, without additional hardware costs, reducing the complexity and maintenance costs of the system, simplifying the equalization management process of the battery pack, and improving the operability and usability of the system. At the same time, through precise capacity calibration and dynamic pressure difference control, it helps to reduce the imbalance phenomenon during the charge and discharge process of the battery pack, extend the service life of the battery pack, and enable reasonable charge and discharge management for each single cell in the battery pack. The application of this control method enables the lithium iron phosphate battery pack to maintain high energy density and power density while achieving more efficient energy management and more stable voltage output, which is of great significance for improving the overall performance and user experience of application scenarios such as electric vehicles and energy storage systems. Description of the Drawings

[0045] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0046] Figure 1 It is a flowchart of the control method for the active equalization lithium iron phosphate hybrid battery device of the present invention;

[0047] Figure 2 It is a diagram of the active equalization supercapacitor device of the present invention. Detailed implementation manners

[0048] To make the objectives, 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 accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0050] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0051] The following further describes the present invention in detail with reference to the drawings:

[0052] See Figure 1 , which is a flowchart of the control method for the active equalization lithium iron phosphate hybrid battery device of the present invention, including the following steps:

[0053] Full charge correction trigger: After the SOC of the lithium iron phosphate battery pack reaches or exceeds 99%, start the active equalization program. First, perform capacity calibration through a coulomb meter to correct the capacity deviation, and simultaneously monitor the voltage differences of each single battery.

[0054] After the State of Charge (SOC) of the lithium iron phosphate battery pack reaches or exceeds 99%, calibrate the coulomb meter to accurately record the battery capacity information, and measure and record the initial voltage distribution of each single cell; then start the active balancing program and set the initial balancing current to 0.05 times the rated capacity of the battery.

[0055] Specifically:

[0056] The Battery Management System (BMS) detects the SOC status of the battery pack;

[0057] When the SOC reaches or exceeds 99%, the Battery Management System (BMS) starts the calibration program of the coulomb meter. Through current detection and integral calculation, ensure that the battery capacity information recorded by the coulomb meter is accurate. The calibration process takes into account the temperature effect of the battery and the comparison between the charge and discharge amount recorded by the coulomb meter and the actual measured change in battery voltage;

[0058] Measure and record the initial voltage distribution: The Battery Management System (BMS) detects the voltage of each single cell in the battery pack one by one, which is achieved through a voltage sensor or an analog-to-digital converter;

[0059] Record the voltage value of each detected single cell to form an initial voltage distribution map.

[0060] Long-term balancing: Adopt a low-current active balancing strategy, where the balancing current does not exceed 0.05 times the rated capacity of the battery, and continuously transfer charges through a flying capacitor or a bidirectional DC-DC conversion topology; specifically:

[0061] Use a flying capacitor or a bidirectional DC-DC conversion topology as the medium for charge transfer. By controlling the switching of switches or adjusting the output voltage and current of the bidirectional DC-DC converter, achieve continuous and stable energy transfer between single cells in the battery pack;

[0062] During the balancing process, detect the voltage of each single cell in the battery pack, and issue a balancing signal based on the detected voltage difference to control the corresponding switch switching or adjust the output of the bidirectional DC-DC converter to compensate for the small voltage difference caused by self-discharge or internal resistance differences;

[0063] The balancing time is set to 2 to 4 hours to ensure that the voltage difference in the battery pack is fully compensated, while avoiding excessive stress or damage to the battery;

[0064] The flying capacitor type balancing circuit uses a balancing capacitor as the carrier for energy transfer. By controlling the switching of switches, switch between the highest voltage cell and the lowest voltage cell to achieve energy absorption and release;

[0065] The two-way DC-DC conversion topology adopts modular equalization. Each single battery or a group of batteries is connected to other batteries through a two-way DC-DC converter to achieve bidirectional energy transfer. By continuously adjusting the output of the two-way DC-DC converter, the voltage difference in the battery pack is gradually reduced.

[0066] Dynamic pressure difference threshold control:

[0067] Real-time monitoring: The voltage of each single battery is collected at intervals, and the standard deviation σ of the voltage in the module is calculated. If the standard deviation σ of the voltage is greater than 30 mV, it is determined that there is an abnormal voltage difference; specifically:

[0068] The standard deviation σ of the voltage of each single battery in the battery module is updated every 5 minutes to evaluate the uniformity of the voltage distribution; if the standard deviation σ of the voltage is less than 30 mV, the current equalization current and equalization strategy are maintained unchanged, and the equalization operation continues; if the standard deviation σ of the voltage is greater than or equal to 30 mV, the dynamic adjustment mechanism is triggered, and measures such as reducing the equalization current to a lower level or pausing the equalization operation are taken according to the degree of voltage difference, and the position of the single battery with abnormal voltage is recorded for subsequent analysis and processing.

[0069] Hierarchical response: When the pressure difference between single batteries exceeds 50 mV, the equalization operation is immediately stopped, and the overvoltage / undervoltage protection mechanism is triggered; when the pressure difference between single batteries is between 30 mV and 50 mV, the equalization current is reduced to 0.02C, and continuous monitoring is carried out. If the pressure difference does not return to the safe range, the equalization operation is terminated.

[0070] The termination of the equalization operation specifically means that when any of the following conditions is met, the equalization operation is terminated:

[0071] The preset equalization duration is reached, and at the end of this equalization duration, the standard deviation σ of the voltage of each single battery in the battery module is less than 20 mV, indicating that the voltage distribution has reached a sufficiently uniform state;

[0072] Or during the equalization process, it is detected that the voltage of any single battery exceeds the preset safe range. At this time, to protect the battery from damage, the equalization operation is immediately terminated.

[0073] The present invention discloses a control system for an active equalization lithium iron phosphate hybrid battery device, which specifically includes the following modules:

[0074] Full charge correction trigger module: It is used to start the active equalization program when the state of charge (SOC) value of the lithium iron phosphate battery pack reaches or exceeds 99%; it also includes a capacity calibration unit, which corrects the capacity deviation through a coulomb meter and synchronously monitors the voltage difference of each single battery.

[0075] Long - term equalization control module: Adopts a low - current active equalization strategy, where the equalization current does not exceed 0.05 times the rated capacity of the battery; the long - term equalization control module is configured with a charge transfer unit, and realizes continuous charge transfer through a flying capacitor or a bidirectional DC - DC conversion topology structure.

[0076] Dynamic pressure difference threshold control module:

[0077] Real - time monitoring unit: Used to collect the voltages of each single - cell battery at intervals and calculate the voltage standard deviation σ within the module; when the voltage standard deviation σ is greater than 30 mV, it is determined that there is an abnormal voltage difference.

[0078] Hierarchical response unit: Conducts hierarchical responses according to the pressure difference between single - cell batteries:

[0079] When the pressure difference exceeds 50 mV, immediately stop the equalization operation and trigger the over - voltage / under - voltage protection mechanism.

[0080] When the pressure difference is between 30 mV and 50 mV, reduce the equalization current to 0.02 times the rated capacity of the battery and continuously monitor; if the pressure difference does not return to the safe range within the specified time, terminate the equalization operation.

[0081] The control system of an active equalization lithium iron phosphate hybrid battery device according to claim 7, characterized in that it further includes:

[0082] Communication and decision - making center: Responsible for data communication and instruction issuance between each module, including receiving data from the real - time monitoring unit, and triggering instructions for full - charge correction, adjusting the equalization current, executing stop equalization or triggering the protection mechanism according to a preset algorithm or logical judgment.

[0083] Protection mechanism execution module: Responds to the instructions of the hierarchical response unit and executes over - voltage / under - voltage protection measures to ensure the safe operation of the battery pack.

[0084] The control system of an active equalization lithium iron phosphate hybrid battery device of the present invention significantly improves the equalization efficiency and safety of the battery pack: Through the full - charge correction trigger module, when the SOC value of the battery pack reaches or exceeds 99%, the active equalization program is started in a timely manner, and the capacity deviation is corrected through the capacity calibration unit, effectively avoiding the problem of battery pack imbalance caused by inconsistent capacities and significantly improving the equalization efficiency. The dynamic pressure difference threshold control module can real - time monitor the voltage differences of each single - cell battery in the battery pack and conduct hierarchical responses according to the size of the pressure difference, effectively preventing over - charge or over - discharge of single - cell batteries and significantly improving the safety of the battery pack.

[0085] Extend the service life of the battery pack: The long-time balancing control module adopts a low-current active balancing strategy, which avoids battery damage that may be caused by high-current balancing. At the same time, it ensures the continuous transfer of charge, helps to reduce the imbalance phenomenon during the charging and discharging process of the battery pack, and thus extends the service life of the battery pack. When the pressure difference reaches a certain level, the hierarchical response unit can timely adjust the balancing current or stop the balancing operation, avoiding premature aging or failure of individual batteries caused by continuous imbalance of the battery pack.

[0086] Improve the intelligence and automation level of the system: The communication and decision-making center, as the "brain" of the system, is responsible for data communication and instruction issuance between modules. It can intelligently trigger commands for full charge correction, adjust the balancing current, execute stop balancing or trigger protection mechanisms according to the data of the real-time monitoring unit and preset algorithms or logical judgments, improving the intelligence and automation level of the system. The protection mechanism execution module can quickly respond to the instructions of the hierarchical response unit and execute overvoltage / undervoltage protection measures, ensuring the safe operation of the battery pack and improving the reliability and stability of the system.

[0087] Reduce maintenance costs and system complexity: The control system of the present invention has a high integration degree with the existing BMS system, without the need to additionally increase hardware costs, reducing the complexity and maintenance costs of the system. Through the integrated control strategy, the balancing management process of the battery pack is simplified, improving the operability and usability of the system.

[0088] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A control method for actively balancing a lithium iron phosphate hybrid battery device, characterized in that: The following steps are involved: Full charge correction trigger: After the SOC of the lithium iron phosphate battery pack reaches or exceeds 99%, the active balancing program is started. First, the capacity is calibrated by the coulomb meter to correct the capacity deviation, and the voltage difference of each single cell is monitored simultaneously; Long-term balancing: low-current active balancing strategy is adopted, and the balancing current does not exceed 0.05 times the rated capacity of the battery, and the charge is continuously transferred through the flying capacitor or bidirectional DC-DC conversion topology; Dynamic differential pressure threshold control: Real-time monitoring: collect the voltage of each single cell at intervals and calculate the voltage standard deviation σ within the module. If the voltage standard deviation σ is greater than 30mV, it is determined that there is an abnormal voltage difference; Graded response: When the voltage difference between single cells exceeds 50mV, the balancing operation is stopped immediately and the overvoltage / undervoltage protection mechanism is triggered; when the voltage difference between single cells is between 30mV and 50mV, the balancing current is reduced to 0.02C and continuously monitored. If the voltage difference does not return to a safe range, the balancing operation is terminated.

2. A control method for actively balancing a lithium iron phosphate hybrid battery device as claimed in claim 1, characterized in that: After the SOC of the lithium iron phosphate battery pack reaches or exceeds 99%, the coulomb meter is calibrated to accurately record the capacity information of the battery, and the initial voltage distribution of each single cell is measured and recorded; then the active balancing program is started, and the initial balancing current is set to 0.05 times the rated capacity of the battery.

3. A control method for actively balancing a lithium iron phosphate hybrid battery device as claimed in claim 2, characterized in that: The coulombmeter is calibrated to accurately record the capacity information of the battery, and the initial voltage distribution of each single cell is measured and recorded as follows: A battery management system BMS detects the SOC state of the battery pack; When the SOC reaches or exceeds 99%, the battery management system BMS starts the coulomb meter calibration procedure. Through current detection and integral calculation, it ensures that the battery capacity information recorded by the coulomb meter is accurate. The calibration process takes into account the temperature effect of the battery and the comparison between the charge and discharge amount recorded by the coulomb meter and the actual measured battery voltage change. Measuring and recording the initial voltage distribution: the battery management system BMS detects the voltage of each single cell in the battery pack one by one, which is achieved through a voltage sensor or an analog-to-digital converter; The voltage value of each single battery detected is recorded to form an initial voltage distribution diagram.

4. The control method of the active balanced lithium iron phosphate hybrid battery device according to claim 1, characterized in that: The long-term equilibrium is specifically: Using flying capacitors or bidirectional DC-DC conversion topology as the medium for charge transfer, by controlling the switching of switches or adjusting the output voltage and current of the bidirectional DC-DC converter, the continuous and stable transfer of energy between the single cells in the battery pack is achieved; During the balancing process, the voltage of each single cell in the battery pack is detected, and a balancing signal is issued according to the detected voltage difference to control the corresponding switch switching or adjust the output of the bidirectional DC-DC converter to compensate for the small voltage difference caused by self-discharge or internal resistance difference; The equalization time is set at 2 to 4 hours to ensure that voltage differences in the battery pack are fully compensated while avoiding excessive stress or damage to the batteries; The flyby capacitor equalization circuit uses an equalization capacitor as a carrier for energy transfer, and switches between the highest voltage cell and the lowest voltage cell by controlling the switching of the switch to achieve energy absorption and release; The bidirectional DC-DC conversion topology adopts modular balancing. Each single battery or a group of batteries is connected to other batteries through a bidirectional DC-DC converter to achieve bidirectional energy transfer. By continuously adjusting the output of the bidirectional DC-DC converter, the voltage difference in the battery pack is gradually reduced.

5. The control method of the active balanced lithium iron phosphate hybrid battery device according to claim 1, characterized in that: The real-time monitoring is specifically to update the voltage standard deviation σ of each single cell in the battery module every 5 minutes to evaluate the uniformity of voltage distribution; if the voltage standard deviation σ is less than 30mV, the current balancing current and balancing strategy are maintained unchanged, and the balancing operation is continued; if the voltage standard deviation σ is greater than or equal to 30mV, the dynamic adjustment mechanism is triggered, and measures such as reducing the balancing current to a lower level or suspending the balancing operation are taken according to the degree of voltage difference, and the location of the single cell with abnormal voltage is recorded for subsequent analysis and processing.

6. The control method of the active balanced lithium iron phosphate hybrid battery device according to claim 1, characterized in that: The balancing operation is terminated when any of the following conditions is met: The preset balancing time is reached, and at the end of this balancing time, the voltage standard deviation σ of each single battery in the battery module is less than 20mV, indicating that the voltage distribution has reached a sufficiently uniform state; Or during the balancing process, if it is detected that the voltage of any single battery exceeds the preset safety range, the balancing operation will be terminated immediately to protect the battery from damage.

7. A control system for an active balanced lithium iron phosphate hybrid battery device, characterized in that: Includes the following modules: Full charge correction trigger module: used to start the active balancing program when the SOC value of the lithium iron phosphate battery pack reaches or exceeds 99%; Long-term balancing control module: adopts low-current active balancing strategy, in which the balancing current does not exceed 0.05 times the rated capacity of the battery; Dynamic pressure difference threshold control module: Real-time monitoring unit: used to collect the voltage of each single cell at intervals and calculate the voltage standard deviation σ within the module; when the voltage standard deviation σ is greater than 30mV, it is determined that there is an abnormal voltage difference; Gradual response unit: Gradual response according to the voltage difference between single cells: When the voltage difference exceeds 50mV, the balancing operation is stopped immediately and the overvoltage / undervoltage protection mechanism is triggered; When the voltage difference is between 30mV and 50mV, the balancing current is reduced to 0.02 times the rated capacity of the battery and continuously monitored; If the pressure difference does not return to the safe range within the specified time, the equalization operation will be terminated.

8. A control system for an active balanced lithium iron phosphate hybrid battery device as claimed in claim 7, characterized in that: The full charge correction trigger module also includes a capacity calibration unit, which performs capacity calibration through a coulomb meter to correct capacity deviation and simultaneously monitors the voltage difference of each single battery.

9. A control system for an active balanced lithium iron phosphate hybrid battery device as claimed in claim 7, characterized in that: The long-term equalization control module is equipped with a charge transfer unit, which realizes continuous charge transfer through a flying capacitor or a bidirectional DC-DC conversion topology.

10. A control system for an active balanced lithium iron phosphate hybrid battery device as claimed in claim 7, characterized in that: Also includes: Communication and decision center: responsible for data communication and command issuance between modules, including receiving data from the real-time monitoring unit, triggering full charge correction, adjusting balancing current, executing commands to stop balancing or triggering protection mechanisms according to preset algorithms or logical judgments; Protection mechanism execution module: responds to the instructions of the hierarchical response unit and executes overvoltage / undervoltage protection measures to ensure the safe operation of the battery pack.

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