Differential pressure-based equalization control method and system

Abstract

The application relates to the technical field of battery equalization, and discloses an equalization control method and system based on pressure difference, which comprises a data acquisition module, a working condition and state analysis module, a pressure difference standard matching module, an equalization demand judgment module, an equalization execution control module and an effect verification module; working condition classification processing is carried out based on bus current data, classification data of static working conditions and dynamic working conditions are generated, and corresponding dynamic pressure difference standards and static pressure difference standards are inquired from a preset pressure difference standard table in combination with a state of charge interval, so that the equalization judgment can distinguish the source of inconsistency between battery monomers under static working conditions and dynamic working conditions, and the equalization judgment result is prevented from being disturbed by Ohm voltage drop generated by large current charging and discharging; the execution time of the equalization operation is limited to the constant voltage stage of the charging process and the bus current is lower than a preset small current threshold value, so that the equalization action is only aimed at the real inconsistency between battery monomers.

Description

Technical Field

[0001] This invention relates to the field of battery balancing technology, specifically to a balancing control method and system based on differential pressure. Background Technology

[0002] Voltage differential equalization is primarily used in lithium-ion batteries and energy storage systems to address performance degradation, capacity reduction, and safety hazards caused by voltage inconsistencies between individual battery cells. This technology aims to ensure uniform voltage across all cells, making it a core element in improving the overall lifespan and safety of battery packs.

[0003] Currently, traditional equalization control methods cannot accurately identify the true causes of battery inconsistency, are easily affected by operating conditions leading to misjudgments, and have unreasonable equalization strategies, affecting equalization effect and efficiency, making it difficult to guarantee the long-term reliability of battery pack operation.

[0004] Therefore, a pressure differential-based equalization control method and system are proposed to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a differential pressure-based equalization control method and system, which solves the problem of ensuring the reliability of battery packs during long-term operation, as mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a pressure differential-based equalization control method and system, the method comprising the following steps: S1. Collect individual cell voltage data, bus current data, and state of charge data of the battery pack; S2. Based on the bus current data, perform operating condition classification processing to generate static and dynamic operating condition classification data; S3. Determine the current state of charge interval based on the state of charge data, and query the corresponding dynamic differential pressure standard and static differential pressure standard from the preset differential pressure standard table according to the state of charge interval and the classification data of the working condition. S4. Calculate the maximum static voltage difference and the maximum dynamic voltage difference based on the individual unit voltage data, and compare them with the dynamic voltage difference standard and the static voltage difference standard to generate a balance activation requirement flag. S5. When the equalization activation demand flag is activated, equalization operation is performed during the constant voltage and low current phase in N consecutive charging cycles. S6. After all the equalization operations of the N charging cycles are completed, repeat steps S1 to S4 to verify the effect. If the exit condition is met, clear the equalization activation requirement flag; otherwise, continue to perform the equalization operation.

[0007] Preferably, the acquisition of individual cell voltage data, bus current data, and state of charge data of the battery pack in step S1 includes the following steps: S11. The battery management system synchronously collects the individual cell voltage data, bus current data and state of charge data of each individual cell at a preset high-frequency sampling frequency. S12. Record the current data within the preset time period and calculate the effective value of the current within that time period.

[0008] Preferably, the generation of static and dynamic operating condition classification data in step S2 includes the following steps: S21. Obtain the effective value of the current and compare the effective value of the current with a preset static operating condition current threshold. S22. When the absolute value of the effective current is less than or equal to the static operating condition current threshold, the current operating condition is classified as a static operating condition; when the absolute value of the effective current is greater than the static operating condition current threshold, the current operating condition is classified as a dynamic operating condition.

[0009] Preferably, querying the corresponding dynamic differential pressure standard and static differential pressure standard in step S3 includes the following steps: S31. Obtain the state of charge data and divide the state of charge range of [0%, 100%] into state of charge intervals, with each interval corresponding to an interval number; S32. A two-dimensional differential pressure standard table is pre-set in the memory of the battery management system. The two-dimensional differential pressure standard table includes dynamic differential pressure standard and static differential pressure standard corresponding to different states of charge intervals. The value of the dynamic differential pressure standard under the same state of charge interval is greater than the value of the static differential pressure standard. S33. Based on the currently determined state of charge range and operating condition classification data, query and output the corresponding dynamic differential pressure standard and static differential pressure standard from the two-dimensional differential pressure standard table.

[0010] Preferably, generating the balanced activation requirement flag in step S4 includes the following steps: S41. Obtain the individual cell voltage data of all individual cells, calculate their maximum and minimum values, and generate the maximum static voltage difference and the maximum dynamic voltage difference accordingly. S42. Within a continuous first preset time period, continuously determine whether the first condition and the second condition are met simultaneously: the first condition is that the maximum static pressure difference is ≥ the static pressure difference standard, and the second condition is that the maximum dynamic pressure difference is ≥ the dynamic pressure difference standard.

[0011] Preferably, the balancing operation in S5 includes the following steps: S51. When the equalization activation demand flag is activated, equalization operation is performed in the next N consecutive charging cycles, where N is a calibrable positive integer. S52. In each charging cycle, the equalization mode is automatically entered only when the charging state enters the constant voltage stage and the bus current is less than the preset small current threshold. S53. In the equalization mode, when passive equalization is used, the bypass resistor is turned on to discharge the individual cells whose individual cell voltage is higher than the average value plus a preset offset; when active equalization is used, energy is transferred from the highest voltage cell to the lowest voltage cell.

[0012] Preferably, the effect verification in S6 includes the following steps: S61. After all the equalization operations of the N charging cycles are completed, repeat steps S1 to S4 to obtain a new maximum static voltage difference and a new maximum dynamic voltage difference. S62. Determine whether the exit conditions are met simultaneously: the exit conditions are that the new maximum static pressure difference is less than the static pressure difference standard, and the new maximum dynamic pressure difference is less than the dynamic pressure difference standard. S63. If the exit condition is met, the balance activation requirement flag is cleared and the balance state is exited; if not, return to step S5, continue to record a new round of balance requirements and perform balance operations.

[0013] Preferably, the step S62 of determining whether the exit conditions are met simultaneously includes the following steps: the dynamic pressure difference standard and the static pressure difference standard are pre-defined based on the DC internal resistance characteristics of the battery system and the consistency requirements of the power battery. The dynamic pressure difference standard is calculated by the effective value of the current under the current operating condition and the DC internal resistance value of the corresponding state of charge interval. The static pressure difference standard is calculated in the same way. The DC internal resistance value is determined by the DC internal resistance characteristic spectrum of the battery system, which reflects the change law of DC internal resistance with state of charge and current ratio.

[0014] Preferably, the system includes a data acquisition module, a working condition and status analysis module, and a differential pressure standard matching module; The data acquisition module collects individual cell voltage data, bus current data and state of charge data of the battery pack through a high-frequency sampling unit, and outputs current effective value data through a current effective value calculation unit. The operating condition and state analysis module receives the current effective value data, classifies the current operating condition into static operating condition and dynamic operating condition through the operating condition classification unit, and determines the current charge state interval through the charge state interval mapping unit, and outputs the operating condition classification data and charge state interval data. The differential pressure standard matching module receives the operating condition classification data and the state of charge interval data, queries the corresponding dynamic differential pressure standard and static differential pressure standard from the preset two-dimensional differential pressure standard table through the differential pressure standard query unit, and outputs the differential pressure standard data.

[0015] Preferably, the system further includes a balanced demand determination module, a balanced execution control module, and an effect verification module; The equalization demand determination module receives the individual voltage data and differential pressure standard data, calculates the maximum static differential pressure and the maximum dynamic differential pressure through the maximum differential pressure calculation unit, generates an equalization activation demand flag through the condition judgment unit, and outputs an equalization activation signal. The equalization execution control module receives the equalization activation signal, records N consecutive charging cycles through the charging cycle counting unit, initiates the equalization operation during the constant voltage and low current charging stage through the constant voltage and low current triggering unit, and completes the discharge and energy transfer of the individual battery cells through the equalization action execution unit. After all the balancing operations of the N charging cycles are completed, the effect verification module re-drives the data acquisition module, operating condition and status analysis module, differential pressure standard matching module and balancing demand determination module to perform effect verification. The exit condition judgment unit determines whether the exit condition is met. If it is met, the balancing activation demand flag is cleared; otherwise, the balancing execution control module continues to perform the balancing operation.

[0016] Compared with the prior art, the present invention provides a pressure differential-based equalization control method and system, which has the following beneficial effects: 1. In this invention, by classifying operating conditions based on bus current data, classification data of static and dynamic operating conditions are generated. Combined with the state of charge interval, the corresponding dynamic and static differential pressure standards are queried from the preset differential pressure standard table. This enables the balance judgment to distinguish the source of inconsistency between battery cells under static and dynamic operating conditions, and avoids interference of the balance judgment result by the ohmic voltage drop caused by high current charging and discharging.

[0017] 2. In this invention, when the equalization activation demand flag is activated, the equalization operation is performed in the constant voltage and low current stage during N consecutive charging cycles. After all the equalization operations in the N charging cycles are completed, the effect is re-verified. If the exit condition is met, the equalization activation demand flag is cleared; otherwise, the equalization operation continues to be performed. This allows the equalization process to be completed step by step according to the actual pressure difference change and the effect to be verified.

[0018] 3. In this invention, by limiting the timing of the balancing operation to the constant voltage stage of the charging process and when the bus current is lower than the preset low current threshold, the balancing action is only aimed at the inconsistency between actual battery cells. Furthermore, the effect verification module re-drives each module to verify the effect after all the balancing operations of N charging cycles are completed, thus forming a closed loop in the balancing control process. Attached Figure Description

[0019] Figure 1 This is a flowchart of a pressure differential-based equalization control method according to the present invention; Figure 2 This is a schematic diagram of the equalization control system based on pressure difference according to the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] For specific implementation examples, please refer to: Figures 1-2 A pressure differential-based equalization control method and system, wherein the method includes the following steps: S1. Collect individual cell voltage data, bus current data, and state of charge data of the battery pack; S2. Based on the bus current data, perform operating condition classification processing to generate static and dynamic operating condition classification data; S3. Determine the current state of charge interval based on the state of charge data, and query the corresponding dynamic differential pressure standard and static differential pressure standard from the preset differential pressure standard table according to the state of charge interval and the classification data of the working condition. S4. Calculate the maximum static voltage difference and the maximum dynamic voltage difference based on the individual voltage data, and compare them with the dynamic voltage difference standard and the static voltage difference standard to generate the equalization activation requirement flag. S5. When the equalization activation demand flag is activated, equalization operation is performed during the constant voltage and low current phase in N consecutive charging cycles. S6. After all equalization operations of N charging cycles are completed, repeat steps S1 to S4 to verify the effect. If the exit condition is met, clear the equalization activation requirement flag; otherwise, continue to perform the equalization operation.

[0022] The steps involved in collecting individual cell voltage data, bus current data, and state of charge data of the battery pack in S1 are as follows: S11. The battery management system synchronously collects the individual cell voltage data, bus current data and state of charge data of each individual cell at a preset high-frequency sampling frequency. S12. Record the current data within a preset time period and calculate the effective value of the current within that time period; The specific steps for calculating the effective value of the current during this period are as follows: After synchronously collecting individual cell voltage data, bus current data, and state of charge data of each battery cell at a preset high-frequency sampling frequency through the battery management system, the bus current data within a preset time period is recorded, and the effective value of the current within that time period is calculated. The specific calculation formula is as follows: ; in, For the first The absolute value of the current at each sampling point. The total number of sampling points within the preset time period. The rated capacity of the battery system, This is the calculated effective value of the current.

[0023] The steps involved in generating static and dynamic operating condition classification data in S2 are as follows: S21. Obtain the effective value of the current and compare the effective value of the current with the preset static operating condition current threshold. S22. When the absolute value of the effective current is less than or equal to the static operating condition current threshold, the current operating condition is classified as a static operating condition; when the absolute value of the effective current is greater than the static operating condition current threshold, the current operating condition is classified as a dynamic operating condition.

[0024] The steps to query the corresponding dynamic differential pressure standard and static differential pressure standard in S3 are as follows: S31. Obtain the state of charge data and divide the state of charge range of [0%, 100%] into state of charge intervals, with each interval corresponding to an interval number; S32. A two-dimensional differential pressure standard table is pre-set in the memory of the battery management system. The two-dimensional differential pressure standard table includes dynamic differential pressure standard and static differential pressure standard corresponding to different states of charge intervals. The value of the dynamic differential pressure standard under the same state of charge interval is greater than the value of the static differential pressure standard. The specific implementation steps for setting up a two-dimensional differential pressure standard table are as follows: First, charge and discharge data of the tested battery cells under different states of charge and current rates were collected experimentally, and DC internal resistance parameters were extracted for each operating condition. Second, based on the extracted internal resistance parameters and the maximum allowable energy loss and thermal runaway boundary of the system, the maximum allowable differential pressure limit per cell under the corresponding operating condition was calculated. Then, using state of charge and current rate as two-dimensional coordinate axes, the calculated differential pressure limit values ​​were mapped to the corresponding coordinate grid to form an initial differential pressure standard matrix. Finally, to ensure the robustness of the control strategy, bilinear interpolation was performed on the empty grids in the matrix, and amplitude limiting correction was applied to the edge region data, ultimately solidifying a two-dimensional differential pressure standard table for subsequent equilibrium determination. The specific matrix generation logic formula is as follows: ; in, This is a preset two-dimensional differential pressure standard table matrix. The first in the matrix Line 1 The corresponding standard value of differential pressure is listed. The number of rows in the matrix corresponds to the total number of preset charge states, The number of columns in the matrix corresponds to the total number of preset current ratio intervals.

[0025] S33. Based on the currently determined state of charge range and operating condition classification data, query and output the corresponding dynamic differential pressure standard and static differential pressure standard from the two-dimensional differential pressure standard table.

[0026] The steps involved in generating the balanced activation demand flag in S4 are as follows: S41. Obtain the individual cell voltage data of all individual cells, calculate their maximum and minimum values, and generate the maximum static voltage difference and the maximum dynamic voltage difference accordingly. The specific steps for calculating the maximum static pressure difference and the maximum dynamic pressure difference are as follows: Obtain the individual cell voltage data of all cells, assuming a total of The first single cell, the first The voltage value of each individual cell is First, calculate the maximum and minimum values ​​of all individual cell voltages. The specific calculation formula is as follows: ; ; in, For the first The voltage value of each individual cell = , , , , It is the maximum value among all individual cell voltages. It is the minimum value among all individual cell voltages; Based on the above maximum and minimum values, the maximum static pressure difference and the maximum dynamic pressure difference are generated, and their specific calculation formulas are as follows: ; ; in, For the maximum static pressure difference, This represents the maximum dynamic pressure difference. S42. Within a continuous first preset time period, continuously determine whether the first condition and the second condition are met simultaneously: the first condition is that the maximum static pressure difference is ≥ the static pressure difference standard, and the second condition is that the maximum dynamic pressure difference is ≥ the dynamic pressure difference standard.

[0027] Performing a load balancing operation in S5 includes the following steps: S51. When the equalization activation demand flag is activated, the equalization operation is performed in the next N consecutive charging cycles, where N is a calibrable positive integer. S52. In each charging cycle, the equalization mode is automatically entered only when the charging state enters the constant voltage stage and the bus current is less than the preset small current threshold. S53. In equalization mode, when passive equalization is used, the bypass resistor is turned on to discharge the cells whose individual cell voltage is higher than the average value plus a preset offset; when active equalization is used, energy is transferred from the highest voltage cell to the lowest voltage cell. The specific implementation steps for passive equilibrium are as follows: The system first calculates the average voltage of all individual cells, then adds a preset offset to this average to determine the discharge threshold. Each individual cell's voltage is checked individually; for any cell with a voltage higher than the discharge threshold, the system activates a bypass resistor to discharge it until its voltage drops below the threshold. The specific calculation formula is as follows: Calculate the average voltage of all individual cells: ; Determine the discharge threshold : ; The bypass resistor will be activated to discharge if the following conditions are met: ; in, This is the average voltage of all individual cells. This refers to the total number of individual battery cells. For the first The voltage value of each individual cell. The preset discharge voltage threshold, This is the preset offset. Indicates that for the first The equalization trigger signal for each individual battery cell This indicates that bypass discharge has been activated. Indicates inaction; The specific implementation steps for active balancing are as follows: The system first identifies the cell with the highest voltage and the cell with the lowest voltage. Then, through the flying capacitor energy transfer unit, excess charge in the high-energy cell is directionally transferred to the low-energy cell. This transfer process continues until the voltage difference between the cells is reduced to an acceptable range. The specific equalization triggering condition formula is as follows: ; in, This is the trigger signal for the active balancing mechanism; 1 indicates triggering, and 0 indicates not triggering. This represents the highest voltage value of all individual cells in the battery pack at the current moment. This represents the lowest voltage value of all individual cells in the battery pack at the current moment. The preset dynamic differential pressure equalization threshold for the system.

[0028] The effect verification in S6 includes the following steps: S61. After all the equalization operations of N charging cycles are completed, repeat steps S1 to S4 to obtain the new maximum static voltage difference and the new maximum dynamic voltage difference. S62. Determine whether the exit conditions are met simultaneously: The exit conditions are that the new maximum static pressure difference is less than the static pressure difference standard and the new maximum dynamic pressure difference is less than the dynamic pressure difference standard. S63. If the exit condition is met, clear the balance activation demand flag and exit the balance state; if not, return to step S5, continue to record the new round of balance demand and perform the balance operation.

[0029] S62 determines whether the exit conditions are met simultaneously by following these steps: The dynamic pressure difference standard and the static pressure difference standard are pre-defined based on the DC internal resistance characteristics of the battery system and the consistency requirements of the power battery. The dynamic pressure difference standard is calculated by the effective value of the current under the current operating condition and the DC internal resistance value of the corresponding state of charge interval. The static pressure difference standard is calculated in the same way. The DC internal resistance value is determined by the DC internal resistance characteristic spectrum of the battery system, which reflects the change law of DC internal resistance with state of charge and current ratio. The specific calculation formula for the dynamic differential pressure standard is as follows: ; in, This is the effective value of the current under the current operating conditions. To correspond to the current state of charge interval DC internal resistance value, For dynamic differential pressure standards; The specific calculation formula for the static differential pressure standard is as follows: ; in, As a static differential pressure standard, It is represented as a static differential pressure reference value that varies with the state of charge, pre-determined based on the DC internal resistance characteristics of the battery system and the consistency requirements of the power battery.

[0030] The system includes a data acquisition module, a working condition and status analysis module, and a differential pressure standard matching module; The data acquisition module collects individual cell voltage data, bus current data, and state of charge data of the battery pack through a high-frequency sampling unit, and outputs the effective value data of the current through the effective value calculation unit. The operating condition and status analysis module receives the effective value of current data, classifies the current operating condition into static operating condition and dynamic operating condition through the operating condition classification unit, and determines the current charge state interval through the charge state interval mapping unit, and outputs the operating condition classification data and charge state interval data. The differential pressure standard matching module receives operating condition classification data and state of charge interval data, queries the corresponding dynamic differential pressure standard and static differential pressure standard from the preset two-dimensional differential pressure standard table through the differential pressure standard query unit, and outputs the differential pressure standard data.

[0031] The system also includes a balanced demand determination module, a balanced execution control module, and an effect verification module; The equalization demand determination module receives individual unit voltage data and differential pressure standard data, calculates the maximum static differential pressure and the maximum dynamic differential pressure through the maximum differential pressure calculation unit, generates an equalization activation demand flag through the condition judgment unit, and outputs an equalization activation signal. The equalization execution control module receives the equalization activation signal, records N consecutive charging cycles through the charging cycle counting unit, initiates the equalization operation during the constant voltage and low current charging stage through the constant voltage and low current triggering unit, and completes the discharge and energy transfer of the individual battery cells through the equalization action execution unit. After all equalization operations in N charging cycles are completed, the effect verification module re-drives the data acquisition module, operating condition and status analysis module, differential pressure standard matching module, and equalization demand determination module to verify the effect. The exit condition judgment unit determines whether the exit condition is met. If it is met, the equalization activation demand flag is cleared; otherwise, the equalization execution control module continues to execute the equalization operation.

[0032] The operation steps of a pressure differential-based equalization control method and system are as follows: Step 1: Data Collection The battery management system synchronously collects individual cell voltage data, bus current data, and state of charge data of the battery pack, records the current data within a preset time period, and calculates the effective current value within that time period.

[0033] Step Two: Classification of Operating Conditions Obtain the effective value of the current and compare it with the preset static operating condition current threshold. If the absolute value of the effective current is less than or equal to the static operating condition current threshold, the current operating condition is classified as a static operating condition; otherwise, it is classified as a dynamic operating condition.

[0034] Step 3: Differential Pressure Standard Matching Obtain state of charge (SOC) data to determine the current SOC range. Based on this SOC range and operating condition classification data, retrieve the corresponding dynamic and static differential pressure standards from the pre-set two-dimensional differential pressure standard table in the battery management system.

[0035] Step 4: Determining the Balanced Demand Based on the voltage data of all individual cells, the maximum and minimum values ​​are calculated to generate the maximum static voltage difference and the maximum dynamic voltage difference. Within a continuous first preset time period, it is continuously determined whether two conditions are met simultaneously: the maximum static voltage difference ≥ the static voltage difference standard, and the maximum dynamic voltage difference ≥ the dynamic voltage difference standard. If both conditions are met, an equalization activation requirement flag is generated and recorded.

[0036] Step 5: Balanced Execution When the equalization activation demand flag is activated, equalization operations are performed in the next N consecutive charging cycles. In each charging cycle, equalization mode is automatically entered only when the charging state enters the constant voltage stage and the bus current is less than a preset low current threshold. In equalization mode, when passive equalization is used, bypass resistors are activated to discharge cells with individual cell voltages higher than the average value plus a preset offset; when active equalization is used, energy transfer is performed from the highest voltage cell to the lowest voltage cell.

[0037] Step Six: Validation of Results After all equalization operations for N charging cycles are completed, steps one through four are re-executed to obtain the new maximum static voltage difference and the new maximum dynamic voltage difference. It is then determined whether the exit conditions are simultaneously met: the new maximum static voltage difference is less than the static voltage difference standard, and the new maximum dynamic voltage difference is less than the dynamic voltage difference standard. If these conditions are met, the equalization activation demand flag is cleared, and the equalization state is exited; otherwise, the process returns to step five to record a new round of equalization demands and execute the equalization operation.

[0038] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pressure differential-based equalization control method, characterized in that: The method includes the following steps: S1. Collect individual cell voltage data, bus current data, and state of charge data of the battery pack; S2. Based on the bus current data, perform operating condition classification processing to generate static and dynamic operating condition classification data; S3. Determine the current state of charge interval based on the state of charge data, and query the corresponding dynamic differential pressure standard and static differential pressure standard from the preset differential pressure standard table according to the state of charge interval and the classification data of the working condition. S4. Calculate the maximum static voltage difference and the maximum dynamic voltage difference based on the individual unit voltage data, and compare them with the dynamic voltage difference standard and the static voltage difference standard to generate a balance activation requirement flag. S5. When the equalization activation demand flag is activated, equalization operation is performed during the constant voltage and low current phase in N consecutive charging cycles. S6. After all the equalization operations of the N charging cycles are completed, repeat steps S1 to S4 to verify the effect. If the exit condition is met, clear the equalization activation requirement flag; otherwise, continue to perform the equalization operation.

2. The pressure difference-based equalization control method according to claim 1, characterized in that: The steps involved in S1 to collect the individual cell voltage data, bus current data, and state of charge data of the battery pack are as follows: S11. The battery management system synchronously collects the individual cell voltage data, bus current data and state of charge data of each individual cell at a preset high-frequency sampling frequency. S12. Record the current data within the preset time period and calculate the effective value of the current within that time period.

3. The pressure difference-based equalization control method according to claim 2, characterized in that: The steps for generating static and dynamic operating condition classification data in S2 are as follows: S21. Obtain the effective value of the current and compare the effective value of the current with a preset static operating condition current threshold. S22. When the absolute value of the effective current is less than or equal to the static operating condition current threshold, the current operating condition is classified as a static operating condition; when the absolute value of the effective current is greater than the static operating condition current threshold, the current operating condition is classified as a dynamic operating condition.

4. The pressure difference-based equalization control method according to claim 3, characterized in that: The steps involved in querying the corresponding dynamic differential pressure standard and static differential pressure standard in step S3 are as follows: S31. Obtain the state of charge data and divide the state of charge range of [0%, 100%] into state of charge intervals, with each interval corresponding to an interval number; S32. A two-dimensional differential pressure standard table is pre-set in the memory of the battery management system. The two-dimensional differential pressure standard table includes dynamic differential pressure standard and static differential pressure standard corresponding to different states of charge intervals. The value of the dynamic differential pressure standard under the same state of charge interval is greater than the value of the static differential pressure standard. S33. Based on the currently determined state of charge range and operating condition classification data, query and output the corresponding dynamic differential pressure standard and static differential pressure standard from the two-dimensional differential pressure standard table.

5. The pressure difference-based equalization control method according to claim 4, characterized in that: The process of generating the balanced activation demand flag in S4 includes the following steps: S41. Obtain the individual cell voltage data of all individual cells, calculate their maximum and minimum values, and generate the maximum static voltage difference and the maximum dynamic voltage difference accordingly. S42. Within a continuous first preset time period, continuously determine whether the first condition and the second condition are met simultaneously: the first condition is that the maximum static pressure difference is ≥ the static pressure difference standard, and the second condition is that the maximum dynamic pressure difference is ≥ the dynamic pressure difference standard. S43. When the first condition and the second condition are met simultaneously, a balanced activation requirement flag is generated and recorded.

6. The pressure difference-based equalization control method according to claim 5, characterized in that: The balancing operation performed in S5 includes the following steps: S51. When the equalization activation demand flag is activated, equalization operation is performed in the next N consecutive charging cycles, where N is a calibrable positive integer. S52. In each charging cycle, the equalization mode is automatically entered only when the charging state enters the constant voltage stage and the bus current is less than the preset small current threshold. S53. In the equalization mode, when passive equalization is used, the bypass resistor is turned on to discharge the individual cells whose individual cell voltage is higher than the average value plus a preset offset; when active equalization is used, energy is transferred from the highest voltage cell to the lowest voltage cell.

7. The pressure differential-based equalization control method according to claim 6, characterized in that: The effect verification in S6 includes the following steps: S61. After all the equalization operations of the N charging cycles are completed, repeat steps S1 to S4 to obtain a new maximum static voltage difference and a new maximum dynamic voltage difference. S62. Determine whether the exit conditions are met simultaneously: the exit conditions are that the new maximum static pressure difference is less than the static pressure difference standard, and the new maximum dynamic pressure difference is less than the dynamic pressure difference standard. S63. If the exit condition is met, the balance activation requirement flag is cleared and the balance state is exited; if not, return to step S5, continue to record a new round of balance requirements and perform balance operations.

8. The pressure differential-based equalization control method according to claim 7, characterized in that: The step S62 for determining whether the exit conditions are met simultaneously includes the following steps: The dynamic pressure difference standard and the static pressure difference standard are pre-defined based on the DC internal resistance characteristics of the battery system and the consistency requirements of the power battery. The dynamic pressure difference standard is calculated by the effective value of the current under the current operating condition and the DC internal resistance value of the corresponding state of charge interval. The static pressure difference standard is calculated in the same way. The DC internal resistance value is determined by the DC internal resistance characteristic spectrum of the battery system, which reflects the change law of DC internal resistance with state of charge and current ratio.

9. A differential pressure-based equalization control system for implementing the differential pressure-based equalization control method according to any one of claims 1-8, characterized in that: The system includes a data acquisition module, a working condition and status analysis module, and a differential pressure standard matching module. The data acquisition module collects individual cell voltage data, bus current data and state of charge data of the battery pack through a high-frequency sampling unit, and outputs current effective value data through a current effective value calculation unit. The operating condition and state analysis module receives the current effective value data, classifies the current operating condition into static operating condition and dynamic operating condition through the operating condition classification unit, and determines the current charge state interval through the charge state interval mapping unit, and outputs the operating condition classification data and charge state interval data. The differential pressure standard matching module receives the operating condition classification data and the state of charge interval data, queries the corresponding dynamic differential pressure standard and static differential pressure standard from the preset two-dimensional differential pressure standard table through the differential pressure standard query unit, and outputs the differential pressure standard data.

10. A differential pressure-based equalization control system according to claim 9, characterized in that: The system also includes a balanced demand determination module, a balanced execution control module, and an effect verification module; The equalization demand determination module receives the individual voltage data and differential pressure standard data, calculates the maximum static differential pressure and the maximum dynamic differential pressure through the maximum differential pressure calculation unit, generates an equalization activation demand flag through the condition judgment unit, and outputs an equalization activation signal. The equalization execution control module receives the equalization activation signal, records N consecutive charging cycles through the charging cycle counting unit, initiates the equalization operation during the constant voltage and low current charging stage through the constant voltage and low current triggering unit, and completes the discharge and energy transfer of the individual battery cells through the equalization action execution unit. After all the balancing operations of the N charging cycles are completed, the effect verification module re-drives the data acquisition module, operating condition and status analysis module, differential pressure standard matching module and balancing demand determination module to perform effect verification. The exit condition judgment unit determines whether the exit condition is met. If it is met, the balancing activation demand flag is cleared; otherwise, the balancing execution control module continues to perform the balancing operation.

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